From: Wenhua Lin <Wenhua.Lin@unisoc.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Rob Herring" <robh+dt@kernel.org>,
"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
"Conor Dooley" <conor+dt@kernel.org>
Cc: Orson Zhai <orsonzhai@gmail.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Chunyan Zhang <zhang.lyra@gmail.com>, <linux-pwm@vger.kernel.org>,
<devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
wenhua lin <wenhua.lin1994@gmail.com>,
Wenhua Lin <Wenhua.Lin@unisoc.com>,
Xiongpeng Wu <xiongpeng.wu@unisoc.com>,
zhaochen su <zhaochen.su29@gmail.com>,
Zhaochen Su <Zhaochen.Su@unisoc.com>,
Xiaolong Wang <Xiaolong.Wang@unisoc.com>
Subject: [PATCH V2 2/6] pwm: sprd: Improve the pwm backlight control function
Date: Thu, 25 Jan 2024 10:55:29 +0800 [thread overview]
Message-ID: <20240125025533.10315-3-Wenhua.Lin@unisoc.com> (raw)
In-Reply-To: <20240125025533.10315-1-Wenhua.Lin@unisoc.com>
The pwm-sprd driver support only 8-bit linear control of backlight. Now,
new requests of supporting 9-bit, 10-bit, 11-bit and 12-bit linear
control of backlight are proposed. Besides, different channels of pwm
could be configured into different linear control of backlight. Thus,
sprd,mod attribute is introduced into dts for every channel of pwm
device. This attribute would determine the value of MOD and eventually
realize the new requirements.
Signed-off-by: Wenhua Lin <Wenhua.Lin@unisoc.com>
---
drivers/pwm/pwm-sprd.c | 42 ++++++++++++++++++++++++++++++++++--------
1 file changed, 34 insertions(+), 8 deletions(-)
diff --git a/drivers/pwm/pwm-sprd.c b/drivers/pwm/pwm-sprd.c
index bc1e3ed13528..cc54aa77c7e6 100644
--- a/drivers/pwm/pwm-sprd.c
+++ b/drivers/pwm/pwm-sprd.c
@@ -18,7 +18,8 @@
#define SPRD_PWM_DUTY 0x8
#define SPRD_PWM_ENABLE 0x18
-#define SPRD_PWM_MOD_MAX GENMASK(7, 0)
+#define SPRD_PWM_MOD_MAX GENMASK(15, 0)
+#define SPRD_PWM_MOD_DEFAULT GENMASK(9, 0)
#define SPRD_PWM_DUTY_MSK GENMASK(15, 0)
#define SPRD_PWM_PRESCALE_MSK GENMASK(7, 0)
#define SPRD_PWM_ENABLE_BIT BIT(0)
@@ -43,6 +44,7 @@ struct sprd_pwm_chip {
const struct sprd_pwm_data *pdata;
int num_pwms;
struct sprd_pwm_chn chn[SPRD_PWM_CHN_NUM];
+ u32 mod[SPRD_PWM_CHN_NUM];
};
static const struct sprd_pwm_data ums512_data = {
@@ -120,7 +122,7 @@ static int sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
*/
val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_PRESCALE);
prescale = val & SPRD_PWM_PRESCALE_MSK;
- tmp = (prescale + 1) * NSEC_PER_SEC * SPRD_PWM_MOD_MAX;
+ tmp = (prescale + 1) * NSEC_PER_SEC * spc->mod[pwm->hwpwm];
state->period = DIV_ROUND_CLOSEST_ULL(tmp, chn->clk_rate);
val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_DUTY);
@@ -140,7 +142,7 @@ static int sprd_pwm_config(struct sprd_pwm_chip *spc, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm];
- u32 prescale, duty;
+ u32 prescale, duty, mod;
u64 tmp;
/*
@@ -148,16 +150,21 @@ static int sprd_pwm_config(struct sprd_pwm_chip *spc, struct pwm_device *pwm,
* The period length is (PRESCALE + 1) * MOD counter steps.
* The duty cycle length is (PRESCALE + 1) * DUTY counter steps.
*
- * To keep the maths simple we're always using MOD = SPRD_PWM_MOD_MAX.
+ * The value for MOD is obtained from dts.
* The value for PRESCALE is selected such that the resulting period
* gets the maximal length not bigger than the requested one with the
- * given settings (MOD = SPRD_PWM_MOD_MAX and input clock).
+ * given settings (MOD and input clock).
*/
- duty = duty_ns * SPRD_PWM_MOD_MAX / period_ns;
+ mod = spc->mod[pwm->hwpwm];
+ duty = duty_ns * mod / period_ns;
tmp = (u64)chn->clk_rate * period_ns;
do_div(tmp, NSEC_PER_SEC);
- prescale = DIV_ROUND_CLOSEST_ULL(tmp, SPRD_PWM_MOD_MAX) - 1;
+ prescale = DIV_ROUND_CLOSEST_ULL(tmp, mod);
+ if (prescale < 1)
+ prescale = 1;
+ prescale--;
+
if (prescale > SPRD_PWM_PRESCALE_MSK)
prescale = SPRD_PWM_PRESCALE_MSK;
@@ -170,7 +177,7 @@ static int sprd_pwm_config(struct sprd_pwm_chip *spc, struct pwm_device *pwm,
* before changing a new configuration to avoid mixed settings.
*/
sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_PRESCALE, prescale);
- sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_MOD, SPRD_PWM_MOD_MAX);
+ sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_MOD, mod);
sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_DUTY, duty);
return 0;
@@ -263,6 +270,21 @@ static int sprd_pwm_clk_init(struct sprd_pwm_chip *spc)
return 0;
}
+static int sprd_pwm_get_mod(struct platform_device *pdev)
+{
+ int i, ret;
+ struct sprd_pwm_chip *spc = platform_get_drvdata(pdev);
+
+ ret = of_property_read_u32_array(pdev->dev.of_node,
+ "sprd,mod", spc->mod, spc->num_pwms);
+ if (ret) {
+ for (i = 0; i < spc->num_pwms; i++)
+ spc->mod[i] = SPRD_PWM_MOD_DEFAULT;
+ }
+
+ return ret;
+}
+
static int sprd_pwm_probe(struct platform_device *pdev)
{
struct sprd_pwm_chip *spc;
@@ -288,6 +310,10 @@ static int sprd_pwm_probe(struct platform_device *pdev)
if (ret)
return ret;
+ ret = sprd_pwm_get_mod(pdev);
+ if (ret)
+ dev_info(&pdev->dev, "get pwm mod failed! Use default setting\n");
+
spc->chip.dev = &pdev->dev;
spc->chip.ops = &sprd_pwm_ops;
spc->chip.npwm = spc->num_pwms;
--
2.17.1
next prev parent reply other threads:[~2024-01-25 3:09 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-25 2:55 [PATCH V2 0/6] pwm: sprd: Modification of UNISOC Platform PWM Driver Wenhua Lin
2024-01-25 2:55 ` [PATCH V2 1/6] pwm: sprd: Add support for UMS9620 Wenhua Lin
2024-01-26 7:24 ` Uwe Kleine-König
2024-01-25 2:55 ` Wenhua Lin [this message]
2024-01-25 7:20 ` [PATCH V2 2/6] pwm: sprd: Improve the pwm backlight control function Chunyan Zhang
2024-01-25 21:13 ` Uwe Kleine-König
2024-01-25 2:55 ` [PATCH V2 3/6] pwm: sprd: Optimize the calculation method of duty Wenhua Lin
2024-01-26 7:30 ` Uwe Kleine-König
2024-01-25 2:55 ` [PATCH V2 4/6] dt-bindings: pwm: sprd: Convert to YAML Wenhua Lin
2024-01-25 17:31 ` Conor Dooley
2024-01-30 22:17 ` Rob Herring
2024-01-25 2:55 ` [PATCH V2 5/6] pwm: sprd: Add sprd,ums9620-pwm compatible Wenhua Lin
2024-01-25 21:08 ` Uwe Kleine-König
2024-01-25 2:55 ` [PATCH V2 6/6] dt-bindings: pwm: sprd: Add sprd,mod attribute Wenhua Lin
2024-01-25 17:24 ` Conor Dooley
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