* [PATCH v3 0/2] Implement sample time consideration for Vybrid's ADC
@ 2015-07-14 13:53 ` Sanchayan Maity
0 siblings, 0 replies; 19+ messages in thread
From: Sanchayan Maity @ 2015-07-14 13:53 UTC (permalink / raw)
To: jic23
Cc: shawn.guo, kernel, robh+dt, pawel.moll, mark.rutland,
ijc+devicetree, galak, B38611, devicetree, linux-iio,
linux-arm-kernel, linux-kernel, stefan, Sanchayan Maity
Hello,
This patchset adds a dt binding for specifying sample time
for the vybrid adc driver and takes this into account for
sampling frequency calculation and related configuration in
the driver.
The patchset is based on top of Stefan's patches here
http://lkml.iu.edu/hypermail/linux/kernel/1505.3/02043.html
which got recently applied.
Changes since v2:
- Use a default value of 1000ns for sample time in the driver
if the property is not specified in the device tree.
- Specify the min-sample-time property in the board device tree
file instead of the top level vfxxx.dtsi file for Vybrid
Changes since v1:
Change from a vendor specific fsl,min-sample-time to non vendor
specific min-sample-time.
Version 2 of the patchset can be found here
https://lkml.org/lkml/2015/6/24/97
Version 1 of the patchset can be found here
http://lkml.iu.edu/hypermail/linux/kernel/1506.1/00026.html
- Sanchayan.
Sanchayan Maity (2):
iio: adc: vf610: Determine sampling frequencies by using minimum
sample time
ARM: dts: vf-colibri: Add property for minimum sample time
.../devicetree/bindings/iio/adc/vf610-adc.txt | 5 ++
arch/arm/boot/dts/vf-colibri.dtsi | 2 +
drivers/iio/adc/vf610_adc.c | 79 ++++++++++++++++++++--
3 files changed, 82 insertions(+), 4 deletions(-)
--
2.4.5
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v3 0/2] Implement sample time consideration for Vybrid's ADC
@ 2015-07-14 13:53 ` Sanchayan Maity
0 siblings, 0 replies; 19+ messages in thread
From: Sanchayan Maity @ 2015-07-14 13:53 UTC (permalink / raw)
To: jic23-DgEjT+Ai2ygdnm+yROfE0A
Cc: shawn.guo-QSEj5FYQhm4dnm+yROfE0A, kernel-bIcnvbaLZ9MEGnE8C9+IrQ,
robh+dt-DgEjT+Ai2ygdnm+yROfE0A, pawel.moll-5wv7dgnIgG8,
mark.rutland-5wv7dgnIgG8, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg,
galak-sgV2jX0FEOL9JmXXK+q4OQ, B38611-KZfg59tc24xl57MIdRCFDg,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-iio-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
linux-kernel-u79uwXL29TY76Z2rM5mHXA, stefan-XLVq0VzYD2Y,
Sanchayan Maity
Hello,
This patchset adds a dt binding for specifying sample time
for the vybrid adc driver and takes this into account for
sampling frequency calculation and related configuration in
the driver.
The patchset is based on top of Stefan's patches here
http://lkml.iu.edu/hypermail/linux/kernel/1505.3/02043.html
which got recently applied.
Changes since v2:
- Use a default value of 1000ns for sample time in the driver
if the property is not specified in the device tree.
- Specify the min-sample-time property in the board device tree
file instead of the top level vfxxx.dtsi file for Vybrid
Changes since v1:
Change from a vendor specific fsl,min-sample-time to non vendor
specific min-sample-time.
Version 2 of the patchset can be found here
https://lkml.org/lkml/2015/6/24/97
Version 1 of the patchset can be found here
http://lkml.iu.edu/hypermail/linux/kernel/1506.1/00026.html
- Sanchayan.
Sanchayan Maity (2):
iio: adc: vf610: Determine sampling frequencies by using minimum
sample time
ARM: dts: vf-colibri: Add property for minimum sample time
.../devicetree/bindings/iio/adc/vf610-adc.txt | 5 ++
arch/arm/boot/dts/vf-colibri.dtsi | 2 +
drivers/iio/adc/vf610_adc.c | 79 ++++++++++++++++++++--
3 files changed, 82 insertions(+), 4 deletions(-)
--
2.4.5
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v3 0/2] Implement sample time consideration for Vybrid's ADC
@ 2015-07-14 13:53 ` Sanchayan Maity
0 siblings, 0 replies; 19+ messages in thread
From: Sanchayan Maity @ 2015-07-14 13:53 UTC (permalink / raw)
To: linux-arm-kernel
Hello,
This patchset adds a dt binding for specifying sample time
for the vybrid adc driver and takes this into account for
sampling frequency calculation and related configuration in
the driver.
The patchset is based on top of Stefan's patches here
http://lkml.iu.edu/hypermail/linux/kernel/1505.3/02043.html
which got recently applied.
Changes since v2:
- Use a default value of 1000ns for sample time in the driver
if the property is not specified in the device tree.
- Specify the min-sample-time property in the board device tree
file instead of the top level vfxxx.dtsi file for Vybrid
Changes since v1:
Change from a vendor specific fsl,min-sample-time to non vendor
specific min-sample-time.
Version 2 of the patchset can be found here
https://lkml.org/lkml/2015/6/24/97
Version 1 of the patchset can be found here
http://lkml.iu.edu/hypermail/linux/kernel/1506.1/00026.html
- Sanchayan.
Sanchayan Maity (2):
iio: adc: vf610: Determine sampling frequencies by using minimum
sample time
ARM: dts: vf-colibri: Add property for minimum sample time
.../devicetree/bindings/iio/adc/vf610-adc.txt | 5 ++
arch/arm/boot/dts/vf-colibri.dtsi | 2 +
drivers/iio/adc/vf610_adc.c | 79 ++++++++++++++++++++--
3 files changed, 82 insertions(+), 4 deletions(-)
--
2.4.5
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v3 1/2] iio: adc: vf610: Determine sampling frequencies by using minimum sample time
2015-07-14 13:53 ` Sanchayan Maity
@ 2015-07-14 13:53 ` Sanchayan Maity
-1 siblings, 0 replies; 19+ messages in thread
From: Sanchayan Maity @ 2015-07-14 13:53 UTC (permalink / raw)
To: jic23
Cc: shawn.guo, kernel, robh+dt, pawel.moll, mark.rutland,
ijc+devicetree, galak, B38611, devicetree, linux-iio,
linux-arm-kernel, linux-kernel, stefan, Sanchayan Maity
The driver currently does not take into account the minimum sample time
as per the Figure 6-8 Chapter 9.1.1 12-bit ADC electrical characteristics.
We set a static amount of cycles instead of considering the sample time
as a given value, which depends on hardware characteristics.
Determine sampling frequencies by first reading the device tree property
node and then calculating the required Long Sample Time Adder (LSTAdder)
value, based on the ADC clock frequency and sample time value obtained
from the device tree. This LSTAdder value is then used for calculating
the sampling frequencies possible.
In case the sample time property is not specified through the device
tree, a safe default value of 1000ns is assumed.
Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
---
.../devicetree/bindings/iio/adc/vf610-adc.txt | 5 ++
drivers/iio/adc/vf610_adc.c | 79 ++++++++++++++++++++--
2 files changed, 80 insertions(+), 4 deletions(-)
diff --git a/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt b/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
index 3eb40e2..1aad051 100644
--- a/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
+++ b/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
@@ -17,6 +17,11 @@ Recommended properties:
- Frequency in normal mode (ADLPC=0, ADHSC=0)
- Frequency in high-speed mode (ADLPC=0, ADHSC=1)
- Frequency in low-power mode (ADLPC=1, ADHSC=0)
+- min-sample-time: Minimum sampling time in nanoseconds. This value has
+ to be chosen according to the conversion mode and the connected analog
+ source resistance (R_as) and capacitance (C_as). Refer the datasheet's
+ operating requirements. A safe default across a wide range of R_as and
+ C_as as well as conversion modes is 1000ns.
Example:
adc0: adc@4003b000 {
diff --git a/drivers/iio/adc/vf610_adc.c b/drivers/iio/adc/vf610_adc.c
index 480f335..23b8fb9 100644
--- a/drivers/iio/adc/vf610_adc.c
+++ b/drivers/iio/adc/vf610_adc.c
@@ -68,6 +68,9 @@
#define VF610_ADC_CLK_DIV8 0x60
#define VF610_ADC_CLK_MASK 0x60
#define VF610_ADC_ADLSMP_LONG 0x10
+#define VF610_ADC_ADSTS_SHORT 0x100
+#define VF610_ADC_ADSTS_NORMAL 0x200
+#define VF610_ADC_ADSTS_LONG 0x300
#define VF610_ADC_ADSTS_MASK 0x300
#define VF610_ADC_ADLPC_EN 0x80
#define VF610_ADC_ADHSC_EN 0x400
@@ -98,6 +101,8 @@
#define VF610_ADC_CALF 0x2
#define VF610_ADC_TIMEOUT msecs_to_jiffies(100)
+#define DEFAULT_SAMPLE_TIME 1000
+
enum clk_sel {
VF610_ADCIOC_BUSCLK_SET,
VF610_ADCIOC_ALTCLK_SET,
@@ -124,6 +129,17 @@ enum conversion_mode_sel {
VF610_ADC_CONV_LOW_POWER,
};
+enum lst_adder_sel {
+ VF610_ADCK_CYCLES_3,
+ VF610_ADCK_CYCLES_5,
+ VF610_ADCK_CYCLES_7,
+ VF610_ADCK_CYCLES_9,
+ VF610_ADCK_CYCLES_13,
+ VF610_ADCK_CYCLES_17,
+ VF610_ADCK_CYCLES_21,
+ VF610_ADCK_CYCLES_25,
+};
+
struct vf610_adc_feature {
enum clk_sel clk_sel;
enum vol_ref vol_ref;
@@ -132,6 +148,8 @@ struct vf610_adc_feature {
int clk_div;
int sample_rate;
int res_mode;
+ u32 lst_adder_index;
+ u32 default_sample_time;
bool calibration;
bool ovwren;
@@ -155,11 +173,13 @@ struct vf610_adc {
};
static const u32 vf610_hw_avgs[] = { 1, 4, 8, 16, 32 };
+static const u32 vf610_lst_adder[] = { 3, 5, 7, 9, 13, 17, 21, 25 };
static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
{
struct vf610_adc_feature *adc_feature = &info->adc_feature;
unsigned long adck_rate, ipg_rate = clk_get_rate(info->clk);
+ u32 adck_period, lst_addr_min;
int divisor, i;
adck_rate = info->max_adck_rate[adc_feature->conv_mode];
@@ -174,6 +194,19 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
}
/*
+ * Determine the long sample time adder value to be used based
+ * on the default minimum sample time provided.
+ */
+ adck_period = NSEC_PER_SEC / adck_rate;
+ lst_addr_min = adc_feature->default_sample_time / adck_period;
+ for (i = 0; i < ARRAY_SIZE(vf610_lst_adder); i++) {
+ if (vf610_lst_adder[i] > lst_addr_min) {
+ adc_feature->lst_adder_index = i;
+ break;
+ }
+ }
+
+ /*
* Calculate ADC sample frequencies
* Sample time unit is ADCK cycles. ADCK clk source is ipg clock,
* which is the same as bus clock.
@@ -182,12 +215,13 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
* SFCAdder: fixed to 6 ADCK cycles
* AverageNum: 1, 4, 8, 16, 32 samples for hardware average.
* BCT (Base Conversion Time): fixed to 25 ADCK cycles for 12 bit mode
- * LSTAdder(Long Sample Time): fixed to 3 ADCK cycles
+ * LSTAdder(Long Sample Time): 3, 5, 7, 9, 13, 17, 21, 25 ADCK cycles
*/
adck_rate = ipg_rate / info->adc_feature.clk_div;
for (i = 0; i < ARRAY_SIZE(vf610_hw_avgs); i++)
info->sample_freq_avail[i] =
- adck_rate / (6 + vf610_hw_avgs[i] * (25 + 3));
+ adck_rate / (6 + vf610_hw_avgs[i] *
+ (25 + vf610_lst_adder[adc_feature->lst_adder_index]));
}
static inline void vf610_adc_cfg_init(struct vf610_adc *info)
@@ -347,8 +381,40 @@ static void vf610_adc_sample_set(struct vf610_adc *info)
break;
}
- /* Use the short sample mode */
- cfg_data &= ~(VF610_ADC_ADLSMP_LONG | VF610_ADC_ADSTS_MASK);
+ /*
+ * Set ADLSMP and ADSTS based on the Long Sample Time Adder value
+ * determined.
+ */
+ switch (adc_feature->lst_adder_index) {
+ case VF610_ADCK_CYCLES_3:
+ break;
+ case VF610_ADCK_CYCLES_5:
+ cfg_data |= VF610_ADC_ADSTS_SHORT;
+ break;
+ case VF610_ADCK_CYCLES_7:
+ cfg_data |= VF610_ADC_ADSTS_NORMAL;
+ break;
+ case VF610_ADCK_CYCLES_9:
+ cfg_data |= VF610_ADC_ADSTS_LONG;
+ break;
+ case VF610_ADCK_CYCLES_13:
+ cfg_data |= VF610_ADC_ADLSMP_LONG;
+ break;
+ case VF610_ADCK_CYCLES_17:
+ cfg_data |= VF610_ADC_ADLSMP_LONG;
+ cfg_data |= VF610_ADC_ADSTS_SHORT;
+ break;
+ case VF610_ADCK_CYCLES_21:
+ cfg_data |= VF610_ADC_ADLSMP_LONG;
+ cfg_data |= VF610_ADC_ADSTS_NORMAL;
+ break;
+ case VF610_ADCK_CYCLES_25:
+ cfg_data |= VF610_ADC_ADLSMP_LONG;
+ cfg_data |= VF610_ADC_ADSTS_NORMAL;
+ break;
+ default:
+ dev_err(info->dev, "error in sample time select\n");
+ }
/* update hardware average selection */
cfg_data &= ~VF610_ADC_AVGS_MASK;
@@ -713,6 +779,11 @@ static int vf610_adc_probe(struct platform_device *pdev)
of_property_read_u32_array(pdev->dev.of_node, "fsl,adck-max-frequency",
info->max_adck_rate, 3);
+ ret = of_property_read_u32(pdev->dev.of_node, "min-sample-time",
+ &info->adc_feature.default_sample_time);
+ if (ret)
+ info->adc_feature.default_sample_time = DEFAULT_SAMPLE_TIME;
+
platform_set_drvdata(pdev, indio_dev);
init_completion(&info->completion);
--
2.4.5
^ permalink raw reply related [flat|nested] 19+ messages in thread
* [PATCH v3 1/2] iio: adc: vf610: Determine sampling frequencies by using minimum sample time
@ 2015-07-14 13:53 ` Sanchayan Maity
0 siblings, 0 replies; 19+ messages in thread
From: Sanchayan Maity @ 2015-07-14 13:53 UTC (permalink / raw)
To: linux-arm-kernel
The driver currently does not take into account the minimum sample time
as per the Figure 6-8 Chapter 9.1.1 12-bit ADC electrical characteristics.
We set a static amount of cycles instead of considering the sample time
as a given value, which depends on hardware characteristics.
Determine sampling frequencies by first reading the device tree property
node and then calculating the required Long Sample Time Adder (LSTAdder)
value, based on the ADC clock frequency and sample time value obtained
from the device tree. This LSTAdder value is then used for calculating
the sampling frequencies possible.
In case the sample time property is not specified through the device
tree, a safe default value of 1000ns is assumed.
Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
---
.../devicetree/bindings/iio/adc/vf610-adc.txt | 5 ++
drivers/iio/adc/vf610_adc.c | 79 ++++++++++++++++++++--
2 files changed, 80 insertions(+), 4 deletions(-)
diff --git a/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt b/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
index 3eb40e2..1aad051 100644
--- a/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
+++ b/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
@@ -17,6 +17,11 @@ Recommended properties:
- Frequency in normal mode (ADLPC=0, ADHSC=0)
- Frequency in high-speed mode (ADLPC=0, ADHSC=1)
- Frequency in low-power mode (ADLPC=1, ADHSC=0)
+- min-sample-time: Minimum sampling time in nanoseconds. This value has
+ to be chosen according to the conversion mode and the connected analog
+ source resistance (R_as) and capacitance (C_as). Refer the datasheet's
+ operating requirements. A safe default across a wide range of R_as and
+ C_as as well as conversion modes is 1000ns.
Example:
adc0: adc at 4003b000 {
diff --git a/drivers/iio/adc/vf610_adc.c b/drivers/iio/adc/vf610_adc.c
index 480f335..23b8fb9 100644
--- a/drivers/iio/adc/vf610_adc.c
+++ b/drivers/iio/adc/vf610_adc.c
@@ -68,6 +68,9 @@
#define VF610_ADC_CLK_DIV8 0x60
#define VF610_ADC_CLK_MASK 0x60
#define VF610_ADC_ADLSMP_LONG 0x10
+#define VF610_ADC_ADSTS_SHORT 0x100
+#define VF610_ADC_ADSTS_NORMAL 0x200
+#define VF610_ADC_ADSTS_LONG 0x300
#define VF610_ADC_ADSTS_MASK 0x300
#define VF610_ADC_ADLPC_EN 0x80
#define VF610_ADC_ADHSC_EN 0x400
@@ -98,6 +101,8 @@
#define VF610_ADC_CALF 0x2
#define VF610_ADC_TIMEOUT msecs_to_jiffies(100)
+#define DEFAULT_SAMPLE_TIME 1000
+
enum clk_sel {
VF610_ADCIOC_BUSCLK_SET,
VF610_ADCIOC_ALTCLK_SET,
@@ -124,6 +129,17 @@ enum conversion_mode_sel {
VF610_ADC_CONV_LOW_POWER,
};
+enum lst_adder_sel {
+ VF610_ADCK_CYCLES_3,
+ VF610_ADCK_CYCLES_5,
+ VF610_ADCK_CYCLES_7,
+ VF610_ADCK_CYCLES_9,
+ VF610_ADCK_CYCLES_13,
+ VF610_ADCK_CYCLES_17,
+ VF610_ADCK_CYCLES_21,
+ VF610_ADCK_CYCLES_25,
+};
+
struct vf610_adc_feature {
enum clk_sel clk_sel;
enum vol_ref vol_ref;
@@ -132,6 +148,8 @@ struct vf610_adc_feature {
int clk_div;
int sample_rate;
int res_mode;
+ u32 lst_adder_index;
+ u32 default_sample_time;
bool calibration;
bool ovwren;
@@ -155,11 +173,13 @@ struct vf610_adc {
};
static const u32 vf610_hw_avgs[] = { 1, 4, 8, 16, 32 };
+static const u32 vf610_lst_adder[] = { 3, 5, 7, 9, 13, 17, 21, 25 };
static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
{
struct vf610_adc_feature *adc_feature = &info->adc_feature;
unsigned long adck_rate, ipg_rate = clk_get_rate(info->clk);
+ u32 adck_period, lst_addr_min;
int divisor, i;
adck_rate = info->max_adck_rate[adc_feature->conv_mode];
@@ -174,6 +194,19 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
}
/*
+ * Determine the long sample time adder value to be used based
+ * on the default minimum sample time provided.
+ */
+ adck_period = NSEC_PER_SEC / adck_rate;
+ lst_addr_min = adc_feature->default_sample_time / adck_period;
+ for (i = 0; i < ARRAY_SIZE(vf610_lst_adder); i++) {
+ if (vf610_lst_adder[i] > lst_addr_min) {
+ adc_feature->lst_adder_index = i;
+ break;
+ }
+ }
+
+ /*
* Calculate ADC sample frequencies
* Sample time unit is ADCK cycles. ADCK clk source is ipg clock,
* which is the same as bus clock.
@@ -182,12 +215,13 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
* SFCAdder: fixed to 6 ADCK cycles
* AverageNum: 1, 4, 8, 16, 32 samples for hardware average.
* BCT (Base Conversion Time): fixed to 25 ADCK cycles for 12 bit mode
- * LSTAdder(Long Sample Time): fixed to 3 ADCK cycles
+ * LSTAdder(Long Sample Time): 3, 5, 7, 9, 13, 17, 21, 25 ADCK cycles
*/
adck_rate = ipg_rate / info->adc_feature.clk_div;
for (i = 0; i < ARRAY_SIZE(vf610_hw_avgs); i++)
info->sample_freq_avail[i] =
- adck_rate / (6 + vf610_hw_avgs[i] * (25 + 3));
+ adck_rate / (6 + vf610_hw_avgs[i] *
+ (25 + vf610_lst_adder[adc_feature->lst_adder_index]));
}
static inline void vf610_adc_cfg_init(struct vf610_adc *info)
@@ -347,8 +381,40 @@ static void vf610_adc_sample_set(struct vf610_adc *info)
break;
}
- /* Use the short sample mode */
- cfg_data &= ~(VF610_ADC_ADLSMP_LONG | VF610_ADC_ADSTS_MASK);
+ /*
+ * Set ADLSMP and ADSTS based on the Long Sample Time Adder value
+ * determined.
+ */
+ switch (adc_feature->lst_adder_index) {
+ case VF610_ADCK_CYCLES_3:
+ break;
+ case VF610_ADCK_CYCLES_5:
+ cfg_data |= VF610_ADC_ADSTS_SHORT;
+ break;
+ case VF610_ADCK_CYCLES_7:
+ cfg_data |= VF610_ADC_ADSTS_NORMAL;
+ break;
+ case VF610_ADCK_CYCLES_9:
+ cfg_data |= VF610_ADC_ADSTS_LONG;
+ break;
+ case VF610_ADCK_CYCLES_13:
+ cfg_data |= VF610_ADC_ADLSMP_LONG;
+ break;
+ case VF610_ADCK_CYCLES_17:
+ cfg_data |= VF610_ADC_ADLSMP_LONG;
+ cfg_data |= VF610_ADC_ADSTS_SHORT;
+ break;
+ case VF610_ADCK_CYCLES_21:
+ cfg_data |= VF610_ADC_ADLSMP_LONG;
+ cfg_data |= VF610_ADC_ADSTS_NORMAL;
+ break;
+ case VF610_ADCK_CYCLES_25:
+ cfg_data |= VF610_ADC_ADLSMP_LONG;
+ cfg_data |= VF610_ADC_ADSTS_NORMAL;
+ break;
+ default:
+ dev_err(info->dev, "error in sample time select\n");
+ }
/* update hardware average selection */
cfg_data &= ~VF610_ADC_AVGS_MASK;
@@ -713,6 +779,11 @@ static int vf610_adc_probe(struct platform_device *pdev)
of_property_read_u32_array(pdev->dev.of_node, "fsl,adck-max-frequency",
info->max_adck_rate, 3);
+ ret = of_property_read_u32(pdev->dev.of_node, "min-sample-time",
+ &info->adc_feature.default_sample_time);
+ if (ret)
+ info->adc_feature.default_sample_time = DEFAULT_SAMPLE_TIME;
+
platform_set_drvdata(pdev, indio_dev);
init_completion(&info->completion);
--
2.4.5
^ permalink raw reply related [flat|nested] 19+ messages in thread
* [PATCH v3 2/2] ARM: dts: vf-colibri: Add property for minimum sample time
2015-07-14 13:53 ` Sanchayan Maity
@ 2015-07-14 13:53 ` Sanchayan Maity
-1 siblings, 0 replies; 19+ messages in thread
From: Sanchayan Maity @ 2015-07-14 13:53 UTC (permalink / raw)
To: jic23
Cc: shawn.guo, kernel, robh+dt, pawel.moll, mark.rutland,
ijc+devicetree, galak, B38611, devicetree, linux-iio,
linux-arm-kernel, linux-kernel, stefan, Sanchayan Maity
Add a device tree property which allows to specify the minimum sample
time which can be used to calculate the actual ADC cycles required
depending on the hardware.
Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
---
arch/arm/boot/dts/vf-colibri.dtsi | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/arm/boot/dts/vf-colibri.dtsi b/arch/arm/boot/dts/vf-colibri.dtsi
index ab10d2e..59f5deb 100644
--- a/arch/arm/boot/dts/vf-colibri.dtsi
+++ b/arch/arm/boot/dts/vf-colibri.dtsi
@@ -16,10 +16,12 @@
};
&adc0 {
+ min-sample-time = <1000>;
status = "okay";
};
&adc1 {
+ min-sample-time = <1000>;
status = "okay";
};
--
2.4.5
^ permalink raw reply related [flat|nested] 19+ messages in thread
* [PATCH v3 2/2] ARM: dts: vf-colibri: Add property for minimum sample time
@ 2015-07-14 13:53 ` Sanchayan Maity
0 siblings, 0 replies; 19+ messages in thread
From: Sanchayan Maity @ 2015-07-14 13:53 UTC (permalink / raw)
To: linux-arm-kernel
Add a device tree property which allows to specify the minimum sample
time which can be used to calculate the actual ADC cycles required
depending on the hardware.
Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
---
arch/arm/boot/dts/vf-colibri.dtsi | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/arm/boot/dts/vf-colibri.dtsi b/arch/arm/boot/dts/vf-colibri.dtsi
index ab10d2e..59f5deb 100644
--- a/arch/arm/boot/dts/vf-colibri.dtsi
+++ b/arch/arm/boot/dts/vf-colibri.dtsi
@@ -16,10 +16,12 @@
};
&adc0 {
+ min-sample-time = <1000>;
status = "okay";
};
&adc1 {
+ min-sample-time = <1000>;
status = "okay";
};
--
2.4.5
^ permalink raw reply related [flat|nested] 19+ messages in thread
* Re: [PATCH v3 2/2] ARM: dts: vf-colibri: Add property for minimum sample time
@ 2015-07-15 1:57 ` Shawn Guo
0 siblings, 0 replies; 19+ messages in thread
From: Shawn Guo @ 2015-07-15 1:57 UTC (permalink / raw)
To: Sanchayan Maity
Cc: jic23, mark.rutland, devicetree, B38611, pawel.moll,
ijc+devicetree, linux-iio, linux-kernel, stefan, robh+dt, kernel,
galak, shawn.guo, linux-arm-kernel
On Tue, Jul 14, 2015 at 07:23:23PM +0530, Sanchayan Maity wrote:
> Add a device tree property which allows to specify the minimum sample
> time which can be used to calculate the actual ADC cycles required
> depending on the hardware.
>
> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
> ---
> arch/arm/boot/dts/vf-colibri.dtsi | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/boot/dts/vf-colibri.dtsi b/arch/arm/boot/dts/vf-colibri.dtsi
> index ab10d2e..59f5deb 100644
> --- a/arch/arm/boot/dts/vf-colibri.dtsi
> +++ b/arch/arm/boot/dts/vf-colibri.dtsi
> @@ -16,10 +16,12 @@
> };
>
> &adc0 {
> + min-sample-time = <1000>;
> status = "okay";
> };
>
> &adc1 {
> + min-sample-time = <1000>;
Since this is the default value anyway, we can just save the patch,
right?
Shawn
> status = "okay";
> };
>
> --
> 2.4.5
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 2/2] ARM: dts: vf-colibri: Add property for minimum sample time
@ 2015-07-15 1:57 ` Shawn Guo
0 siblings, 0 replies; 19+ messages in thread
From: Shawn Guo @ 2015-07-15 1:57 UTC (permalink / raw)
To: Sanchayan Maity
Cc: jic23-DgEjT+Ai2ygdnm+yROfE0A, mark.rutland-5wv7dgnIgG8,
devicetree-u79uwXL29TY76Z2rM5mHXA, B38611-KZfg59tc24xl57MIdRCFDg,
pawel.moll-5wv7dgnIgG8, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg,
linux-iio-u79uwXL29TY76Z2rM5mHXA,
linux-kernel-u79uwXL29TY76Z2rM5mHXA, stefan-XLVq0VzYD2Y,
robh+dt-DgEjT+Ai2ygdnm+yROfE0A, kernel-bIcnvbaLZ9MEGnE8C9+IrQ,
galak-sgV2jX0FEOL9JmXXK+q4OQ, shawn.guo-QSEj5FYQhm4dnm+yROfE0A,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r
On Tue, Jul 14, 2015 at 07:23:23PM +0530, Sanchayan Maity wrote:
> Add a device tree property which allows to specify the minimum sample
> time which can be used to calculate the actual ADC cycles required
> depending on the hardware.
>
> Signed-off-by: Sanchayan Maity <maitysanchayan-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
> arch/arm/boot/dts/vf-colibri.dtsi | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/boot/dts/vf-colibri.dtsi b/arch/arm/boot/dts/vf-colibri.dtsi
> index ab10d2e..59f5deb 100644
> --- a/arch/arm/boot/dts/vf-colibri.dtsi
> +++ b/arch/arm/boot/dts/vf-colibri.dtsi
> @@ -16,10 +16,12 @@
> };
>
> &adc0 {
> + min-sample-time = <1000>;
> status = "okay";
> };
>
> &adc1 {
> + min-sample-time = <1000>;
Since this is the default value anyway, we can just save the patch,
right?
Shawn
> status = "okay";
> };
>
> --
> 2.4.5
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v3 2/2] ARM: dts: vf-colibri: Add property for minimum sample time
@ 2015-07-15 1:57 ` Shawn Guo
0 siblings, 0 replies; 19+ messages in thread
From: Shawn Guo @ 2015-07-15 1:57 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, Jul 14, 2015 at 07:23:23PM +0530, Sanchayan Maity wrote:
> Add a device tree property which allows to specify the minimum sample
> time which can be used to calculate the actual ADC cycles required
> depending on the hardware.
>
> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
> ---
> arch/arm/boot/dts/vf-colibri.dtsi | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/boot/dts/vf-colibri.dtsi b/arch/arm/boot/dts/vf-colibri.dtsi
> index ab10d2e..59f5deb 100644
> --- a/arch/arm/boot/dts/vf-colibri.dtsi
> +++ b/arch/arm/boot/dts/vf-colibri.dtsi
> @@ -16,10 +16,12 @@
> };
>
> &adc0 {
> + min-sample-time = <1000>;
> status = "okay";
> };
>
> &adc1 {
> + min-sample-time = <1000>;
Since this is the default value anyway, we can just save the patch,
right?
Shawn
> status = "okay";
> };
>
> --
> 2.4.5
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 2/2] ARM: dts: vf-colibri: Add property for minimum sample time
2015-07-15 1:57 ` Shawn Guo
(?)
@ 2015-07-15 13:02 ` Stefan Agner
-1 siblings, 0 replies; 19+ messages in thread
From: Stefan Agner @ 2015-07-15 13:02 UTC (permalink / raw)
To: Shawn Guo
Cc: Sanchayan Maity, jic23, mark.rutland, devicetree, B38611,
pawel.moll, ijc+devicetree, linux-iio, linux-kernel, robh+dt,
kernel, galak, shawn.guo, linux-arm-kernel
On 2015-07-15 03:57, Shawn Guo wrote:
> On Tue, Jul 14, 2015 at 07:23:23PM +0530, Sanchayan Maity wrote:
>> Add a device tree property which allows to specify the minimum sample
>> time which can be used to calculate the actual ADC cycles required
>> depending on the hardware.
>>
>> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
>> ---
>> arch/arm/boot/dts/vf-colibri.dtsi | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/vf-colibri.dtsi b/arch/arm/boot/dts/vf-colibri.dtsi
>> index ab10d2e..59f5deb 100644
>> --- a/arch/arm/boot/dts/vf-colibri.dtsi
>> +++ b/arch/arm/boot/dts/vf-colibri.dtsi
>> @@ -16,10 +16,12 @@
>> };
>>
>> &adc0 {
>> + min-sample-time = <1000>;
>> status = "okay";
>> };
>>
>> &adc1 {
>> + min-sample-time = <1000>;
>
> Since this is the default value anyway, we can just save the patch,
> right?
I thought it would be nice to be explicit here and define this value
which we verified internally.
On the other hand, we did not derived the minimum value from the DS
(using the capacity/resistance of the actual analog source connected) to
maximize the sampling frequency, hence I'm also ok with not explicitly
defining a value.
--
Stefan
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 2/2] ARM: dts: vf-colibri: Add property for minimum sample time
@ 2015-07-15 13:02 ` Stefan Agner
0 siblings, 0 replies; 19+ messages in thread
From: Stefan Agner @ 2015-07-15 13:02 UTC (permalink / raw)
To: Shawn Guo
Cc: Sanchayan Maity, jic23-DgEjT+Ai2ygdnm+yROfE0A,
mark.rutland-5wv7dgnIgG8, devicetree-u79uwXL29TY76Z2rM5mHXA,
B38611-KZfg59tc24xl57MIdRCFDg, pawel.moll-5wv7dgnIgG8,
ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg,
linux-iio-u79uwXL29TY76Z2rM5mHXA,
linux-kernel-u79uwXL29TY76Z2rM5mHXA,
robh+dt-DgEjT+Ai2ygdnm+yROfE0A, kernel-bIcnvbaLZ9MEGnE8C9+IrQ,
galak-sgV2jX0FEOL9JmXXK+q4OQ, shawn.guo-QSEj5FYQhm4dnm+yROfE0A,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r
On 2015-07-15 03:57, Shawn Guo wrote:
> On Tue, Jul 14, 2015 at 07:23:23PM +0530, Sanchayan Maity wrote:
>> Add a device tree property which allows to specify the minimum sample
>> time which can be used to calculate the actual ADC cycles required
>> depending on the hardware.
>>
>> Signed-off-by: Sanchayan Maity <maitysanchayan-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> ---
>> arch/arm/boot/dts/vf-colibri.dtsi | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/vf-colibri.dtsi b/arch/arm/boot/dts/vf-colibri.dtsi
>> index ab10d2e..59f5deb 100644
>> --- a/arch/arm/boot/dts/vf-colibri.dtsi
>> +++ b/arch/arm/boot/dts/vf-colibri.dtsi
>> @@ -16,10 +16,12 @@
>> };
>>
>> &adc0 {
>> + min-sample-time = <1000>;
>> status = "okay";
>> };
>>
>> &adc1 {
>> + min-sample-time = <1000>;
>
> Since this is the default value anyway, we can just save the patch,
> right?
I thought it would be nice to be explicit here and define this value
which we verified internally.
On the other hand, we did not derived the minimum value from the DS
(using the capacity/resistance of the actual analog source connected) to
maximize the sampling frequency, hence I'm also ok with not explicitly
defining a value.
--
Stefan
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v3 2/2] ARM: dts: vf-colibri: Add property for minimum sample time
@ 2015-07-15 13:02 ` Stefan Agner
0 siblings, 0 replies; 19+ messages in thread
From: Stefan Agner @ 2015-07-15 13:02 UTC (permalink / raw)
To: linux-arm-kernel
On 2015-07-15 03:57, Shawn Guo wrote:
> On Tue, Jul 14, 2015 at 07:23:23PM +0530, Sanchayan Maity wrote:
>> Add a device tree property which allows to specify the minimum sample
>> time which can be used to calculate the actual ADC cycles required
>> depending on the hardware.
>>
>> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
>> ---
>> arch/arm/boot/dts/vf-colibri.dtsi | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/vf-colibri.dtsi b/arch/arm/boot/dts/vf-colibri.dtsi
>> index ab10d2e..59f5deb 100644
>> --- a/arch/arm/boot/dts/vf-colibri.dtsi
>> +++ b/arch/arm/boot/dts/vf-colibri.dtsi
>> @@ -16,10 +16,12 @@
>> };
>>
>> &adc0 {
>> + min-sample-time = <1000>;
>> status = "okay";
>> };
>>
>> &adc1 {
>> + min-sample-time = <1000>;
>
> Since this is the default value anyway, we can just save the patch,
> right?
I thought it would be nice to be explicit here and define this value
which we verified internally.
On the other hand, we did not derived the minimum value from the DS
(using the capacity/resistance of the actual analog source connected) to
maximize the sampling frequency, hence I'm also ok with not explicitly
defining a value.
--
Stefan
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 2/2] ARM: dts: vf-colibri: Add property for minimum sample time
@ 2015-07-19 12:44 ` Jonathan Cameron
0 siblings, 0 replies; 19+ messages in thread
From: Jonathan Cameron @ 2015-07-19 12:44 UTC (permalink / raw)
To: Stefan Agner, Shawn Guo
Cc: Sanchayan Maity, mark.rutland, devicetree, B38611, pawel.moll,
ijc+devicetree, linux-iio, linux-kernel, robh+dt, kernel, galak,
shawn.guo, linux-arm-kernel
On 15/07/15 14:02, Stefan Agner wrote:
> On 2015-07-15 03:57, Shawn Guo wrote:
>> On Tue, Jul 14, 2015 at 07:23:23PM +0530, Sanchayan Maity wrote:
>>> Add a device tree property which allows to specify the minimum sample
>>> time which can be used to calculate the actual ADC cycles required
>>> depending on the hardware.
>>>
>>> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
>>> ---
>>> arch/arm/boot/dts/vf-colibri.dtsi | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/arch/arm/boot/dts/vf-colibri.dtsi b/arch/arm/boot/dts/vf-colibri.dtsi
>>> index ab10d2e..59f5deb 100644
>>> --- a/arch/arm/boot/dts/vf-colibri.dtsi
>>> +++ b/arch/arm/boot/dts/vf-colibri.dtsi
>>> @@ -16,10 +16,12 @@
>>> };
>>>
>>> &adc0 {
>>> + min-sample-time = <1000>;
>>> status = "okay";
>>> };
>>>
>>> &adc1 {
>>> + min-sample-time = <1000>;
>>
>> Since this is the default value anyway, we can just save the patch,
>> right?
>
> I thought it would be nice to be explicit here and define this value
> which we verified internally.
>
> On the other hand, we did not derived the minimum value from the DS
> (using the capacity/resistance of the actual analog source connected) to
> maximize the sampling frequency, hence I'm also ok with not explicitly
> defining a value.
I'll drop this patch then and we are all happy (I think)
>
> --
> Stefan
> --
> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 2/2] ARM: dts: vf-colibri: Add property for minimum sample time
@ 2015-07-19 12:44 ` Jonathan Cameron
0 siblings, 0 replies; 19+ messages in thread
From: Jonathan Cameron @ 2015-07-19 12:44 UTC (permalink / raw)
To: Stefan Agner, Shawn Guo
Cc: Sanchayan Maity, mark.rutland-5wv7dgnIgG8,
devicetree-u79uwXL29TY76Z2rM5mHXA, B38611-KZfg59tc24xl57MIdRCFDg,
pawel.moll-5wv7dgnIgG8, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg,
linux-iio-u79uwXL29TY76Z2rM5mHXA,
linux-kernel-u79uwXL29TY76Z2rM5mHXA,
robh+dt-DgEjT+Ai2ygdnm+yROfE0A, kernel-bIcnvbaLZ9MEGnE8C9+IrQ,
galak-sgV2jX0FEOL9JmXXK+q4OQ, shawn.guo-QSEj5FYQhm4dnm+yROfE0A,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r
On 15/07/15 14:02, Stefan Agner wrote:
> On 2015-07-15 03:57, Shawn Guo wrote:
>> On Tue, Jul 14, 2015 at 07:23:23PM +0530, Sanchayan Maity wrote:
>>> Add a device tree property which allows to specify the minimum sample
>>> time which can be used to calculate the actual ADC cycles required
>>> depending on the hardware.
>>>
>>> Signed-off-by: Sanchayan Maity <maitysanchayan-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>> ---
>>> arch/arm/boot/dts/vf-colibri.dtsi | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/arch/arm/boot/dts/vf-colibri.dtsi b/arch/arm/boot/dts/vf-colibri.dtsi
>>> index ab10d2e..59f5deb 100644
>>> --- a/arch/arm/boot/dts/vf-colibri.dtsi
>>> +++ b/arch/arm/boot/dts/vf-colibri.dtsi
>>> @@ -16,10 +16,12 @@
>>> };
>>>
>>> &adc0 {
>>> + min-sample-time = <1000>;
>>> status = "okay";
>>> };
>>>
>>> &adc1 {
>>> + min-sample-time = <1000>;
>>
>> Since this is the default value anyway, we can just save the patch,
>> right?
>
> I thought it would be nice to be explicit here and define this value
> which we verified internally.
>
> On the other hand, we did not derived the minimum value from the DS
> (using the capacity/resistance of the actual analog source connected) to
> maximize the sampling frequency, hence I'm also ok with not explicitly
> defining a value.
I'll drop this patch then and we are all happy (I think)
>
> --
> Stefan
> --
> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v3 2/2] ARM: dts: vf-colibri: Add property for minimum sample time
@ 2015-07-19 12:44 ` Jonathan Cameron
0 siblings, 0 replies; 19+ messages in thread
From: Jonathan Cameron @ 2015-07-19 12:44 UTC (permalink / raw)
To: linux-arm-kernel
On 15/07/15 14:02, Stefan Agner wrote:
> On 2015-07-15 03:57, Shawn Guo wrote:
>> On Tue, Jul 14, 2015 at 07:23:23PM +0530, Sanchayan Maity wrote:
>>> Add a device tree property which allows to specify the minimum sample
>>> time which can be used to calculate the actual ADC cycles required
>>> depending on the hardware.
>>>
>>> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
>>> ---
>>> arch/arm/boot/dts/vf-colibri.dtsi | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/arch/arm/boot/dts/vf-colibri.dtsi b/arch/arm/boot/dts/vf-colibri.dtsi
>>> index ab10d2e..59f5deb 100644
>>> --- a/arch/arm/boot/dts/vf-colibri.dtsi
>>> +++ b/arch/arm/boot/dts/vf-colibri.dtsi
>>> @@ -16,10 +16,12 @@
>>> };
>>>
>>> &adc0 {
>>> + min-sample-time = <1000>;
>>> status = "okay";
>>> };
>>>
>>> &adc1 {
>>> + min-sample-time = <1000>;
>>
>> Since this is the default value anyway, we can just save the patch,
>> right?
>
> I thought it would be nice to be explicit here and define this value
> which we verified internally.
>
> On the other hand, we did not derived the minimum value from the DS
> (using the capacity/resistance of the actual analog source connected) to
> maximize the sampling frequency, hence I'm also ok with not explicitly
> defining a value.
I'll drop this patch then and we are all happy (I think)
>
> --
> Stefan
> --
> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> the body of a message to majordomo at vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 1/2] iio: adc: vf610: Determine sampling frequencies by using minimum sample time
@ 2015-07-19 12:48 ` Jonathan Cameron
0 siblings, 0 replies; 19+ messages in thread
From: Jonathan Cameron @ 2015-07-19 12:48 UTC (permalink / raw)
To: Sanchayan Maity
Cc: shawn.guo, kernel, robh+dt, pawel.moll, mark.rutland,
ijc+devicetree, galak, B38611, devicetree, linux-iio,
linux-arm-kernel, linux-kernel, stefan
On 14/07/15 14:53, Sanchayan Maity wrote:
> The driver currently does not take into account the minimum sample time
> as per the Figure 6-8 Chapter 9.1.1 12-bit ADC electrical characteristics.
> We set a static amount of cycles instead of considering the sample time
> as a given value, which depends on hardware characteristics.
>
> Determine sampling frequencies by first reading the device tree property
> node and then calculating the required Long Sample Time Adder (LSTAdder)
> value, based on the ADC clock frequency and sample time value obtained
> from the device tree. This LSTAdder value is then used for calculating
> the sampling frequencies possible.
>
> In case the sample time property is not specified through the device
> tree, a safe default value of 1000ns is assumed.
>
> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
Applied with the Acks from Stefan and Fugang as the patch has changed very little
from the previous version.
Applied to the togreg branch of iio.git - initially pushed out as testing for
the autobuilders to play with it.
Thanks,
Jonathan
> ---
> .../devicetree/bindings/iio/adc/vf610-adc.txt | 5 ++
> drivers/iio/adc/vf610_adc.c | 79 ++++++++++++++++++++--
> 2 files changed, 80 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt b/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
> index 3eb40e2..1aad051 100644
> --- a/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
> +++ b/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
> @@ -17,6 +17,11 @@ Recommended properties:
> - Frequency in normal mode (ADLPC=0, ADHSC=0)
> - Frequency in high-speed mode (ADLPC=0, ADHSC=1)
> - Frequency in low-power mode (ADLPC=1, ADHSC=0)
> +- min-sample-time: Minimum sampling time in nanoseconds. This value has
> + to be chosen according to the conversion mode and the connected analog
> + source resistance (R_as) and capacitance (C_as). Refer the datasheet's
> + operating requirements. A safe default across a wide range of R_as and
> + C_as as well as conversion modes is 1000ns.
>
> Example:
> adc0: adc@4003b000 {
> diff --git a/drivers/iio/adc/vf610_adc.c b/drivers/iio/adc/vf610_adc.c
> index 480f335..23b8fb9 100644
> --- a/drivers/iio/adc/vf610_adc.c
> +++ b/drivers/iio/adc/vf610_adc.c
> @@ -68,6 +68,9 @@
> #define VF610_ADC_CLK_DIV8 0x60
> #define VF610_ADC_CLK_MASK 0x60
> #define VF610_ADC_ADLSMP_LONG 0x10
> +#define VF610_ADC_ADSTS_SHORT 0x100
> +#define VF610_ADC_ADSTS_NORMAL 0x200
> +#define VF610_ADC_ADSTS_LONG 0x300
> #define VF610_ADC_ADSTS_MASK 0x300
> #define VF610_ADC_ADLPC_EN 0x80
> #define VF610_ADC_ADHSC_EN 0x400
> @@ -98,6 +101,8 @@
> #define VF610_ADC_CALF 0x2
> #define VF610_ADC_TIMEOUT msecs_to_jiffies(100)
>
> +#define DEFAULT_SAMPLE_TIME 1000
> +
> enum clk_sel {
> VF610_ADCIOC_BUSCLK_SET,
> VF610_ADCIOC_ALTCLK_SET,
> @@ -124,6 +129,17 @@ enum conversion_mode_sel {
> VF610_ADC_CONV_LOW_POWER,
> };
>
> +enum lst_adder_sel {
> + VF610_ADCK_CYCLES_3,
> + VF610_ADCK_CYCLES_5,
> + VF610_ADCK_CYCLES_7,
> + VF610_ADCK_CYCLES_9,
> + VF610_ADCK_CYCLES_13,
> + VF610_ADCK_CYCLES_17,
> + VF610_ADCK_CYCLES_21,
> + VF610_ADCK_CYCLES_25,
> +};
> +
> struct vf610_adc_feature {
> enum clk_sel clk_sel;
> enum vol_ref vol_ref;
> @@ -132,6 +148,8 @@ struct vf610_adc_feature {
> int clk_div;
> int sample_rate;
> int res_mode;
> + u32 lst_adder_index;
> + u32 default_sample_time;
>
> bool calibration;
> bool ovwren;
> @@ -155,11 +173,13 @@ struct vf610_adc {
> };
>
> static const u32 vf610_hw_avgs[] = { 1, 4, 8, 16, 32 };
> +static const u32 vf610_lst_adder[] = { 3, 5, 7, 9, 13, 17, 21, 25 };
>
> static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
> {
> struct vf610_adc_feature *adc_feature = &info->adc_feature;
> unsigned long adck_rate, ipg_rate = clk_get_rate(info->clk);
> + u32 adck_period, lst_addr_min;
> int divisor, i;
>
> adck_rate = info->max_adck_rate[adc_feature->conv_mode];
> @@ -174,6 +194,19 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
> }
>
> /*
> + * Determine the long sample time adder value to be used based
> + * on the default minimum sample time provided.
> + */
> + adck_period = NSEC_PER_SEC / adck_rate;
> + lst_addr_min = adc_feature->default_sample_time / adck_period;
> + for (i = 0; i < ARRAY_SIZE(vf610_lst_adder); i++) {
> + if (vf610_lst_adder[i] > lst_addr_min) {
> + adc_feature->lst_adder_index = i;
> + break;
> + }
> + }
> +
> + /*
> * Calculate ADC sample frequencies
> * Sample time unit is ADCK cycles. ADCK clk source is ipg clock,
> * which is the same as bus clock.
> @@ -182,12 +215,13 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
> * SFCAdder: fixed to 6 ADCK cycles
> * AverageNum: 1, 4, 8, 16, 32 samples for hardware average.
> * BCT (Base Conversion Time): fixed to 25 ADCK cycles for 12 bit mode
> - * LSTAdder(Long Sample Time): fixed to 3 ADCK cycles
> + * LSTAdder(Long Sample Time): 3, 5, 7, 9, 13, 17, 21, 25 ADCK cycles
> */
> adck_rate = ipg_rate / info->adc_feature.clk_div;
> for (i = 0; i < ARRAY_SIZE(vf610_hw_avgs); i++)
> info->sample_freq_avail[i] =
> - adck_rate / (6 + vf610_hw_avgs[i] * (25 + 3));
> + adck_rate / (6 + vf610_hw_avgs[i] *
> + (25 + vf610_lst_adder[adc_feature->lst_adder_index]));
> }
>
> static inline void vf610_adc_cfg_init(struct vf610_adc *info)
> @@ -347,8 +381,40 @@ static void vf610_adc_sample_set(struct vf610_adc *info)
> break;
> }
>
> - /* Use the short sample mode */
> - cfg_data &= ~(VF610_ADC_ADLSMP_LONG | VF610_ADC_ADSTS_MASK);
> + /*
> + * Set ADLSMP and ADSTS based on the Long Sample Time Adder value
> + * determined.
> + */
> + switch (adc_feature->lst_adder_index) {
> + case VF610_ADCK_CYCLES_3:
> + break;
> + case VF610_ADCK_CYCLES_5:
> + cfg_data |= VF610_ADC_ADSTS_SHORT;
> + break;
> + case VF610_ADCK_CYCLES_7:
> + cfg_data |= VF610_ADC_ADSTS_NORMAL;
> + break;
> + case VF610_ADCK_CYCLES_9:
> + cfg_data |= VF610_ADC_ADSTS_LONG;
> + break;
> + case VF610_ADCK_CYCLES_13:
> + cfg_data |= VF610_ADC_ADLSMP_LONG;
> + break;
> + case VF610_ADCK_CYCLES_17:
> + cfg_data |= VF610_ADC_ADLSMP_LONG;
> + cfg_data |= VF610_ADC_ADSTS_SHORT;
> + break;
> + case VF610_ADCK_CYCLES_21:
> + cfg_data |= VF610_ADC_ADLSMP_LONG;
> + cfg_data |= VF610_ADC_ADSTS_NORMAL;
> + break;
> + case VF610_ADCK_CYCLES_25:
> + cfg_data |= VF610_ADC_ADLSMP_LONG;
> + cfg_data |= VF610_ADC_ADSTS_NORMAL;
> + break;
> + default:
> + dev_err(info->dev, "error in sample time select\n");
> + }
>
> /* update hardware average selection */
> cfg_data &= ~VF610_ADC_AVGS_MASK;
> @@ -713,6 +779,11 @@ static int vf610_adc_probe(struct platform_device *pdev)
> of_property_read_u32_array(pdev->dev.of_node, "fsl,adck-max-frequency",
> info->max_adck_rate, 3);
>
> + ret = of_property_read_u32(pdev->dev.of_node, "min-sample-time",
> + &info->adc_feature.default_sample_time);
> + if (ret)
> + info->adc_feature.default_sample_time = DEFAULT_SAMPLE_TIME;
> +
> platform_set_drvdata(pdev, indio_dev);
>
> init_completion(&info->completion);
>
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 1/2] iio: adc: vf610: Determine sampling frequencies by using minimum sample time
@ 2015-07-19 12:48 ` Jonathan Cameron
0 siblings, 0 replies; 19+ messages in thread
From: Jonathan Cameron @ 2015-07-19 12:48 UTC (permalink / raw)
To: Sanchayan Maity
Cc: shawn.guo-QSEj5FYQhm4dnm+yROfE0A, kernel-bIcnvbaLZ9MEGnE8C9+IrQ,
robh+dt-DgEjT+Ai2ygdnm+yROfE0A, pawel.moll-5wv7dgnIgG8,
mark.rutland-5wv7dgnIgG8, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg,
galak-sgV2jX0FEOL9JmXXK+q4OQ, B38611-KZfg59tc24xl57MIdRCFDg,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-iio-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
linux-kernel-u79uwXL29TY76Z2rM5mHXA, stefan-XLVq0VzYD2Y
On 14/07/15 14:53, Sanchayan Maity wrote:
> The driver currently does not take into account the minimum sample time
> as per the Figure 6-8 Chapter 9.1.1 12-bit ADC electrical characteristics.
> We set a static amount of cycles instead of considering the sample time
> as a given value, which depends on hardware characteristics.
>
> Determine sampling frequencies by first reading the device tree property
> node and then calculating the required Long Sample Time Adder (LSTAdder)
> value, based on the ADC clock frequency and sample time value obtained
> from the device tree. This LSTAdder value is then used for calculating
> the sampling frequencies possible.
>
> In case the sample time property is not specified through the device
> tree, a safe default value of 1000ns is assumed.
>
> Signed-off-by: Sanchayan Maity <maitysanchayan-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Applied with the Acks from Stefan and Fugang as the patch has changed very little
from the previous version.
Applied to the togreg branch of iio.git - initially pushed out as testing for
the autobuilders to play with it.
Thanks,
Jonathan
> ---
> .../devicetree/bindings/iio/adc/vf610-adc.txt | 5 ++
> drivers/iio/adc/vf610_adc.c | 79 ++++++++++++++++++++--
> 2 files changed, 80 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt b/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
> index 3eb40e2..1aad051 100644
> --- a/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
> +++ b/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
> @@ -17,6 +17,11 @@ Recommended properties:
> - Frequency in normal mode (ADLPC=0, ADHSC=0)
> - Frequency in high-speed mode (ADLPC=0, ADHSC=1)
> - Frequency in low-power mode (ADLPC=1, ADHSC=0)
> +- min-sample-time: Minimum sampling time in nanoseconds. This value has
> + to be chosen according to the conversion mode and the connected analog
> + source resistance (R_as) and capacitance (C_as). Refer the datasheet's
> + operating requirements. A safe default across a wide range of R_as and
> + C_as as well as conversion modes is 1000ns.
>
> Example:
> adc0: adc@4003b000 {
> diff --git a/drivers/iio/adc/vf610_adc.c b/drivers/iio/adc/vf610_adc.c
> index 480f335..23b8fb9 100644
> --- a/drivers/iio/adc/vf610_adc.c
> +++ b/drivers/iio/adc/vf610_adc.c
> @@ -68,6 +68,9 @@
> #define VF610_ADC_CLK_DIV8 0x60
> #define VF610_ADC_CLK_MASK 0x60
> #define VF610_ADC_ADLSMP_LONG 0x10
> +#define VF610_ADC_ADSTS_SHORT 0x100
> +#define VF610_ADC_ADSTS_NORMAL 0x200
> +#define VF610_ADC_ADSTS_LONG 0x300
> #define VF610_ADC_ADSTS_MASK 0x300
> #define VF610_ADC_ADLPC_EN 0x80
> #define VF610_ADC_ADHSC_EN 0x400
> @@ -98,6 +101,8 @@
> #define VF610_ADC_CALF 0x2
> #define VF610_ADC_TIMEOUT msecs_to_jiffies(100)
>
> +#define DEFAULT_SAMPLE_TIME 1000
> +
> enum clk_sel {
> VF610_ADCIOC_BUSCLK_SET,
> VF610_ADCIOC_ALTCLK_SET,
> @@ -124,6 +129,17 @@ enum conversion_mode_sel {
> VF610_ADC_CONV_LOW_POWER,
> };
>
> +enum lst_adder_sel {
> + VF610_ADCK_CYCLES_3,
> + VF610_ADCK_CYCLES_5,
> + VF610_ADCK_CYCLES_7,
> + VF610_ADCK_CYCLES_9,
> + VF610_ADCK_CYCLES_13,
> + VF610_ADCK_CYCLES_17,
> + VF610_ADCK_CYCLES_21,
> + VF610_ADCK_CYCLES_25,
> +};
> +
> struct vf610_adc_feature {
> enum clk_sel clk_sel;
> enum vol_ref vol_ref;
> @@ -132,6 +148,8 @@ struct vf610_adc_feature {
> int clk_div;
> int sample_rate;
> int res_mode;
> + u32 lst_adder_index;
> + u32 default_sample_time;
>
> bool calibration;
> bool ovwren;
> @@ -155,11 +173,13 @@ struct vf610_adc {
> };
>
> static const u32 vf610_hw_avgs[] = { 1, 4, 8, 16, 32 };
> +static const u32 vf610_lst_adder[] = { 3, 5, 7, 9, 13, 17, 21, 25 };
>
> static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
> {
> struct vf610_adc_feature *adc_feature = &info->adc_feature;
> unsigned long adck_rate, ipg_rate = clk_get_rate(info->clk);
> + u32 adck_period, lst_addr_min;
> int divisor, i;
>
> adck_rate = info->max_adck_rate[adc_feature->conv_mode];
> @@ -174,6 +194,19 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
> }
>
> /*
> + * Determine the long sample time adder value to be used based
> + * on the default minimum sample time provided.
> + */
> + adck_period = NSEC_PER_SEC / adck_rate;
> + lst_addr_min = adc_feature->default_sample_time / adck_period;
> + for (i = 0; i < ARRAY_SIZE(vf610_lst_adder); i++) {
> + if (vf610_lst_adder[i] > lst_addr_min) {
> + adc_feature->lst_adder_index = i;
> + break;
> + }
> + }
> +
> + /*
> * Calculate ADC sample frequencies
> * Sample time unit is ADCK cycles. ADCK clk source is ipg clock,
> * which is the same as bus clock.
> @@ -182,12 +215,13 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
> * SFCAdder: fixed to 6 ADCK cycles
> * AverageNum: 1, 4, 8, 16, 32 samples for hardware average.
> * BCT (Base Conversion Time): fixed to 25 ADCK cycles for 12 bit mode
> - * LSTAdder(Long Sample Time): fixed to 3 ADCK cycles
> + * LSTAdder(Long Sample Time): 3, 5, 7, 9, 13, 17, 21, 25 ADCK cycles
> */
> adck_rate = ipg_rate / info->adc_feature.clk_div;
> for (i = 0; i < ARRAY_SIZE(vf610_hw_avgs); i++)
> info->sample_freq_avail[i] =
> - adck_rate / (6 + vf610_hw_avgs[i] * (25 + 3));
> + adck_rate / (6 + vf610_hw_avgs[i] *
> + (25 + vf610_lst_adder[adc_feature->lst_adder_index]));
> }
>
> static inline void vf610_adc_cfg_init(struct vf610_adc *info)
> @@ -347,8 +381,40 @@ static void vf610_adc_sample_set(struct vf610_adc *info)
> break;
> }
>
> - /* Use the short sample mode */
> - cfg_data &= ~(VF610_ADC_ADLSMP_LONG | VF610_ADC_ADSTS_MASK);
> + /*
> + * Set ADLSMP and ADSTS based on the Long Sample Time Adder value
> + * determined.
> + */
> + switch (adc_feature->lst_adder_index) {
> + case VF610_ADCK_CYCLES_3:
> + break;
> + case VF610_ADCK_CYCLES_5:
> + cfg_data |= VF610_ADC_ADSTS_SHORT;
> + break;
> + case VF610_ADCK_CYCLES_7:
> + cfg_data |= VF610_ADC_ADSTS_NORMAL;
> + break;
> + case VF610_ADCK_CYCLES_9:
> + cfg_data |= VF610_ADC_ADSTS_LONG;
> + break;
> + case VF610_ADCK_CYCLES_13:
> + cfg_data |= VF610_ADC_ADLSMP_LONG;
> + break;
> + case VF610_ADCK_CYCLES_17:
> + cfg_data |= VF610_ADC_ADLSMP_LONG;
> + cfg_data |= VF610_ADC_ADSTS_SHORT;
> + break;
> + case VF610_ADCK_CYCLES_21:
> + cfg_data |= VF610_ADC_ADLSMP_LONG;
> + cfg_data |= VF610_ADC_ADSTS_NORMAL;
> + break;
> + case VF610_ADCK_CYCLES_25:
> + cfg_data |= VF610_ADC_ADLSMP_LONG;
> + cfg_data |= VF610_ADC_ADSTS_NORMAL;
> + break;
> + default:
> + dev_err(info->dev, "error in sample time select\n");
> + }
>
> /* update hardware average selection */
> cfg_data &= ~VF610_ADC_AVGS_MASK;
> @@ -713,6 +779,11 @@ static int vf610_adc_probe(struct platform_device *pdev)
> of_property_read_u32_array(pdev->dev.of_node, "fsl,adck-max-frequency",
> info->max_adck_rate, 3);
>
> + ret = of_property_read_u32(pdev->dev.of_node, "min-sample-time",
> + &info->adc_feature.default_sample_time);
> + if (ret)
> + info->adc_feature.default_sample_time = DEFAULT_SAMPLE_TIME;
> +
> platform_set_drvdata(pdev, indio_dev);
>
> init_completion(&info->completion);
>
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v3 1/2] iio: adc: vf610: Determine sampling frequencies by using minimum sample time
@ 2015-07-19 12:48 ` Jonathan Cameron
0 siblings, 0 replies; 19+ messages in thread
From: Jonathan Cameron @ 2015-07-19 12:48 UTC (permalink / raw)
To: linux-arm-kernel
On 14/07/15 14:53, Sanchayan Maity wrote:
> The driver currently does not take into account the minimum sample time
> as per the Figure 6-8 Chapter 9.1.1 12-bit ADC electrical characteristics.
> We set a static amount of cycles instead of considering the sample time
> as a given value, which depends on hardware characteristics.
>
> Determine sampling frequencies by first reading the device tree property
> node and then calculating the required Long Sample Time Adder (LSTAdder)
> value, based on the ADC clock frequency and sample time value obtained
> from the device tree. This LSTAdder value is then used for calculating
> the sampling frequencies possible.
>
> In case the sample time property is not specified through the device
> tree, a safe default value of 1000ns is assumed.
>
> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
Applied with the Acks from Stefan and Fugang as the patch has changed very little
from the previous version.
Applied to the togreg branch of iio.git - initially pushed out as testing for
the autobuilders to play with it.
Thanks,
Jonathan
> ---
> .../devicetree/bindings/iio/adc/vf610-adc.txt | 5 ++
> drivers/iio/adc/vf610_adc.c | 79 ++++++++++++++++++++--
> 2 files changed, 80 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt b/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
> index 3eb40e2..1aad051 100644
> --- a/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
> +++ b/Documentation/devicetree/bindings/iio/adc/vf610-adc.txt
> @@ -17,6 +17,11 @@ Recommended properties:
> - Frequency in normal mode (ADLPC=0, ADHSC=0)
> - Frequency in high-speed mode (ADLPC=0, ADHSC=1)
> - Frequency in low-power mode (ADLPC=1, ADHSC=0)
> +- min-sample-time: Minimum sampling time in nanoseconds. This value has
> + to be chosen according to the conversion mode and the connected analog
> + source resistance (R_as) and capacitance (C_as). Refer the datasheet's
> + operating requirements. A safe default across a wide range of R_as and
> + C_as as well as conversion modes is 1000ns.
>
> Example:
> adc0: adc at 4003b000 {
> diff --git a/drivers/iio/adc/vf610_adc.c b/drivers/iio/adc/vf610_adc.c
> index 480f335..23b8fb9 100644
> --- a/drivers/iio/adc/vf610_adc.c
> +++ b/drivers/iio/adc/vf610_adc.c
> @@ -68,6 +68,9 @@
> #define VF610_ADC_CLK_DIV8 0x60
> #define VF610_ADC_CLK_MASK 0x60
> #define VF610_ADC_ADLSMP_LONG 0x10
> +#define VF610_ADC_ADSTS_SHORT 0x100
> +#define VF610_ADC_ADSTS_NORMAL 0x200
> +#define VF610_ADC_ADSTS_LONG 0x300
> #define VF610_ADC_ADSTS_MASK 0x300
> #define VF610_ADC_ADLPC_EN 0x80
> #define VF610_ADC_ADHSC_EN 0x400
> @@ -98,6 +101,8 @@
> #define VF610_ADC_CALF 0x2
> #define VF610_ADC_TIMEOUT msecs_to_jiffies(100)
>
> +#define DEFAULT_SAMPLE_TIME 1000
> +
> enum clk_sel {
> VF610_ADCIOC_BUSCLK_SET,
> VF610_ADCIOC_ALTCLK_SET,
> @@ -124,6 +129,17 @@ enum conversion_mode_sel {
> VF610_ADC_CONV_LOW_POWER,
> };
>
> +enum lst_adder_sel {
> + VF610_ADCK_CYCLES_3,
> + VF610_ADCK_CYCLES_5,
> + VF610_ADCK_CYCLES_7,
> + VF610_ADCK_CYCLES_9,
> + VF610_ADCK_CYCLES_13,
> + VF610_ADCK_CYCLES_17,
> + VF610_ADCK_CYCLES_21,
> + VF610_ADCK_CYCLES_25,
> +};
> +
> struct vf610_adc_feature {
> enum clk_sel clk_sel;
> enum vol_ref vol_ref;
> @@ -132,6 +148,8 @@ struct vf610_adc_feature {
> int clk_div;
> int sample_rate;
> int res_mode;
> + u32 lst_adder_index;
> + u32 default_sample_time;
>
> bool calibration;
> bool ovwren;
> @@ -155,11 +173,13 @@ struct vf610_adc {
> };
>
> static const u32 vf610_hw_avgs[] = { 1, 4, 8, 16, 32 };
> +static const u32 vf610_lst_adder[] = { 3, 5, 7, 9, 13, 17, 21, 25 };
>
> static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
> {
> struct vf610_adc_feature *adc_feature = &info->adc_feature;
> unsigned long adck_rate, ipg_rate = clk_get_rate(info->clk);
> + u32 adck_period, lst_addr_min;
> int divisor, i;
>
> adck_rate = info->max_adck_rate[adc_feature->conv_mode];
> @@ -174,6 +194,19 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
> }
>
> /*
> + * Determine the long sample time adder value to be used based
> + * on the default minimum sample time provided.
> + */
> + adck_period = NSEC_PER_SEC / adck_rate;
> + lst_addr_min = adc_feature->default_sample_time / adck_period;
> + for (i = 0; i < ARRAY_SIZE(vf610_lst_adder); i++) {
> + if (vf610_lst_adder[i] > lst_addr_min) {
> + adc_feature->lst_adder_index = i;
> + break;
> + }
> + }
> +
> + /*
> * Calculate ADC sample frequencies
> * Sample time unit is ADCK cycles. ADCK clk source is ipg clock,
> * which is the same as bus clock.
> @@ -182,12 +215,13 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
> * SFCAdder: fixed to 6 ADCK cycles
> * AverageNum: 1, 4, 8, 16, 32 samples for hardware average.
> * BCT (Base Conversion Time): fixed to 25 ADCK cycles for 12 bit mode
> - * LSTAdder(Long Sample Time): fixed to 3 ADCK cycles
> + * LSTAdder(Long Sample Time): 3, 5, 7, 9, 13, 17, 21, 25 ADCK cycles
> */
> adck_rate = ipg_rate / info->adc_feature.clk_div;
> for (i = 0; i < ARRAY_SIZE(vf610_hw_avgs); i++)
> info->sample_freq_avail[i] =
> - adck_rate / (6 + vf610_hw_avgs[i] * (25 + 3));
> + adck_rate / (6 + vf610_hw_avgs[i] *
> + (25 + vf610_lst_adder[adc_feature->lst_adder_index]));
> }
>
> static inline void vf610_adc_cfg_init(struct vf610_adc *info)
> @@ -347,8 +381,40 @@ static void vf610_adc_sample_set(struct vf610_adc *info)
> break;
> }
>
> - /* Use the short sample mode */
> - cfg_data &= ~(VF610_ADC_ADLSMP_LONG | VF610_ADC_ADSTS_MASK);
> + /*
> + * Set ADLSMP and ADSTS based on the Long Sample Time Adder value
> + * determined.
> + */
> + switch (adc_feature->lst_adder_index) {
> + case VF610_ADCK_CYCLES_3:
> + break;
> + case VF610_ADCK_CYCLES_5:
> + cfg_data |= VF610_ADC_ADSTS_SHORT;
> + break;
> + case VF610_ADCK_CYCLES_7:
> + cfg_data |= VF610_ADC_ADSTS_NORMAL;
> + break;
> + case VF610_ADCK_CYCLES_9:
> + cfg_data |= VF610_ADC_ADSTS_LONG;
> + break;
> + case VF610_ADCK_CYCLES_13:
> + cfg_data |= VF610_ADC_ADLSMP_LONG;
> + break;
> + case VF610_ADCK_CYCLES_17:
> + cfg_data |= VF610_ADC_ADLSMP_LONG;
> + cfg_data |= VF610_ADC_ADSTS_SHORT;
> + break;
> + case VF610_ADCK_CYCLES_21:
> + cfg_data |= VF610_ADC_ADLSMP_LONG;
> + cfg_data |= VF610_ADC_ADSTS_NORMAL;
> + break;
> + case VF610_ADCK_CYCLES_25:
> + cfg_data |= VF610_ADC_ADLSMP_LONG;
> + cfg_data |= VF610_ADC_ADSTS_NORMAL;
> + break;
> + default:
> + dev_err(info->dev, "error in sample time select\n");
> + }
>
> /* update hardware average selection */
> cfg_data &= ~VF610_ADC_AVGS_MASK;
> @@ -713,6 +779,11 @@ static int vf610_adc_probe(struct platform_device *pdev)
> of_property_read_u32_array(pdev->dev.of_node, "fsl,adck-max-frequency",
> info->max_adck_rate, 3);
>
> + ret = of_property_read_u32(pdev->dev.of_node, "min-sample-time",
> + &info->adc_feature.default_sample_time);
> + if (ret)
> + info->adc_feature.default_sample_time = DEFAULT_SAMPLE_TIME;
> +
> platform_set_drvdata(pdev, indio_dev);
>
> init_completion(&info->completion);
>
^ permalink raw reply [flat|nested] 19+ messages in thread
end of thread, other threads:[~2015-07-19 12:48 UTC | newest]
Thread overview: 19+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-07-14 13:53 [PATCH v3 0/2] Implement sample time consideration for Vybrid's ADC Sanchayan Maity
2015-07-14 13:53 ` Sanchayan Maity
2015-07-14 13:53 ` Sanchayan Maity
2015-07-14 13:53 ` [PATCH v3 1/2] iio: adc: vf610: Determine sampling frequencies by using minimum sample time Sanchayan Maity
2015-07-14 13:53 ` Sanchayan Maity
2015-07-19 12:48 ` Jonathan Cameron
2015-07-19 12:48 ` Jonathan Cameron
2015-07-19 12:48 ` Jonathan Cameron
2015-07-14 13:53 ` [PATCH v3 2/2] ARM: dts: vf-colibri: Add property for " Sanchayan Maity
2015-07-14 13:53 ` Sanchayan Maity
2015-07-15 1:57 ` Shawn Guo
2015-07-15 1:57 ` Shawn Guo
2015-07-15 1:57 ` Shawn Guo
2015-07-15 13:02 ` Stefan Agner
2015-07-15 13:02 ` Stefan Agner
2015-07-15 13:02 ` Stefan Agner
2015-07-19 12:44 ` Jonathan Cameron
2015-07-19 12:44 ` Jonathan Cameron
2015-07-19 12:44 ` Jonathan Cameron
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