* [PATCH] i2c: omap: fix bus recovery setup
@ 2015-07-08 14:35 Jan Luebbe
2015-07-12 15:32 ` Alexander Sverdlin
` (2 more replies)
0 siblings, 3 replies; 8+ messages in thread
From: Jan Luebbe @ 2015-07-08 14:35 UTC (permalink / raw
To: linux-arm-kernel
At least on the AM335x, enabling OMAP_I2C_SYSTEST_ST_EN is not enough to
allow direct access to the SCL and SDA pins. In addition to ST_EN, we
need to set the TMODE to 0b11 (Loop back & SDA/SCL IO mode select).
Also, as the reset values of SCL_O and SDA_O are 0 (which means "drive
low level"), we need to set them to 1 (which means "high-impedance") to
avoid unwanted changes on the pins.
As a precaution, reset all these bits to their default values after
recovery is complete.
Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
---
drivers/i2c/busses/i2c-omap.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index d1c22e3fdd14..fc9bf7f30e35 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -1247,7 +1247,14 @@ static void omap_i2c_prepare_recovery(struct i2c_adapter *adap)
u32 reg;
reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
+ /* enable test mode */
reg |= OMAP_I2C_SYSTEST_ST_EN;
+ /* select SDA/SCL IO mode */
+ reg |= 3 << OMAP_I2C_SYSTEST_TMODE_SHIFT;
+ /* set SCL to high-impedance state (reset value is 0) */
+ reg |= OMAP_I2C_SYSTEST_SCL_O;
+ /* set SDA to high-impedance state (reset value is 0) */
+ reg |= OMAP_I2C_SYSTEST_SDA_O;
omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
}
@@ -1257,7 +1264,11 @@ static void omap_i2c_unprepare_recovery(struct i2c_adapter *adap)
u32 reg;
reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
+ /* restore reset values */
reg &= ~OMAP_I2C_SYSTEST_ST_EN;
+ reg &= ~OMAP_I2C_SYSTEST_TMODE_MASK;
+ reg &= ~OMAP_I2C_SYSTEST_SCL_O;
+ reg &= ~OMAP_I2C_SYSTEST_SDA_O;
omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
}
--
2.1.4
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH] i2c: omap: fix bus recovery setup
2015-07-08 14:35 [PATCH] i2c: omap: fix bus recovery setup Jan Luebbe
@ 2015-07-12 15:32 ` Alexander Sverdlin
2015-07-14 11:10 ` Wolfram Sang
2015-07-31 10:51 ` Wolfram Sang
2 siblings, 0 replies; 8+ messages in thread
From: Alexander Sverdlin @ 2015-07-12 15:32 UTC (permalink / raw
To: linux-arm-kernel
On 08/07/15 16:35, Jan Luebbe wrote:
> At least on the AM335x, enabling OMAP_I2C_SYSTEST_ST_EN is not enough to
> allow direct access to the SCL and SDA pins. In addition to ST_EN, we
> need to set the TMODE to 0b11 (Loop back & SDA/SCL IO mode select).
> Also, as the reset values of SCL_O and SDA_O are 0 (which means "drive
> low level"), we need to set them to 1 (which means "high-impedance") to
> avoid unwanted changes on the pins.
>
> As a precaution, reset all these bits to their default values after
> recovery is complete.
>
> Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
Tested with oscilloscope on Beagle Bone Black, without the patch nothing
meningful appears on SCL during recovery, with the patch I'm able to see
the recovery pulses.
Tested-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
> ---
> drivers/i2c/busses/i2c-omap.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index d1c22e3fdd14..fc9bf7f30e35 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -1247,7 +1247,14 @@ static void omap_i2c_prepare_recovery(struct i2c_adapter *adap)
> u32 reg;
>
> reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
> + /* enable test mode */
> reg |= OMAP_I2C_SYSTEST_ST_EN;
> + /* select SDA/SCL IO mode */
> + reg |= 3 << OMAP_I2C_SYSTEST_TMODE_SHIFT;
> + /* set SCL to high-impedance state (reset value is 0) */
> + reg |= OMAP_I2C_SYSTEST_SCL_O;
> + /* set SDA to high-impedance state (reset value is 0) */
> + reg |= OMAP_I2C_SYSTEST_SDA_O;
> omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
> }
>
> @@ -1257,7 +1264,11 @@ static void omap_i2c_unprepare_recovery(struct i2c_adapter *adap)
> u32 reg;
>
> reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
> + /* restore reset values */
> reg &= ~OMAP_I2C_SYSTEST_ST_EN;
> + reg &= ~OMAP_I2C_SYSTEST_TMODE_MASK;
> + reg &= ~OMAP_I2C_SYSTEST_SCL_O;
> + reg &= ~OMAP_I2C_SYSTEST_SDA_O;
> omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
> }
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] i2c: omap: fix bus recovery setup
2015-07-08 14:35 [PATCH] i2c: omap: fix bus recovery setup Jan Luebbe
2015-07-12 15:32 ` Alexander Sverdlin
@ 2015-07-14 11:10 ` Wolfram Sang
2015-07-14 12:10 ` Grygorii Strashko
2015-07-31 10:51 ` Wolfram Sang
2 siblings, 1 reply; 8+ messages in thread
From: Wolfram Sang @ 2015-07-14 11:10 UTC (permalink / raw
To: linux-arm-kernel
On Wed, Jul 08, 2015 at 04:35:27PM +0200, Jan Luebbe wrote:
> At least on the AM335x, enabling OMAP_I2C_SYSTEST_ST_EN is not enough to
Felipe: it seems you did not need this; is this AM335x specific?
> allow direct access to the SCL and SDA pins. In addition to ST_EN, we
> need to set the TMODE to 0b11 (Loop back & SDA/SCL IO mode select).
> Also, as the reset values of SCL_O and SDA_O are 0 (which means "drive
> low level"), we need to set them to 1 (which means "high-impedance") to
> avoid unwanted changes on the pins.
>
> As a precaution, reset all these bits to their default values after
> recovery is complete.
>
> Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
> ---
> drivers/i2c/busses/i2c-omap.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index d1c22e3fdd14..fc9bf7f30e35 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -1247,7 +1247,14 @@ static void omap_i2c_prepare_recovery(struct i2c_adapter *adap)
> u32 reg;
>
> reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
> + /* enable test mode */
> reg |= OMAP_I2C_SYSTEST_ST_EN;
> + /* select SDA/SCL IO mode */
> + reg |= 3 << OMAP_I2C_SYSTEST_TMODE_SHIFT;
> + /* set SCL to high-impedance state (reset value is 0) */
> + reg |= OMAP_I2C_SYSTEST_SCL_O;
> + /* set SDA to high-impedance state (reset value is 0) */
> + reg |= OMAP_I2C_SYSTEST_SDA_O;
> omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
> }
>
> @@ -1257,7 +1264,11 @@ static void omap_i2c_unprepare_recovery(struct i2c_adapter *adap)
> u32 reg;
>
> reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
> + /* restore reset values */
> reg &= ~OMAP_I2C_SYSTEST_ST_EN;
> + reg &= ~OMAP_I2C_SYSTEST_TMODE_MASK;
> + reg &= ~OMAP_I2C_SYSTEST_SCL_O;
> + reg &= ~OMAP_I2C_SYSTEST_SDA_O;
> omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
> }
>
> --
> 2.1.4
>
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* [PATCH] i2c: omap: fix bus recovery setup
2015-07-14 11:10 ` Wolfram Sang
@ 2015-07-14 12:10 ` Grygorii Strashko
2015-07-14 12:12 ` Wolfram Sang
0 siblings, 1 reply; 8+ messages in thread
From: Grygorii Strashko @ 2015-07-14 12:10 UTC (permalink / raw
To: linux-arm-kernel
Hi Wolfram,
On 07/14/2015 02:10 PM, Wolfram Sang wrote:
> On Wed, Jul 08, 2015 at 04:35:27PM +0200, Jan Luebbe wrote:
>> At least on the AM335x, enabling OMAP_I2C_SYSTEST_ST_EN is not enough to
>
> Felipe: it seems you did not need this; is this AM335x specific?
We need it (Felipe's reply can be delayed).
It's not AM335x specific. TMODE has to be configured for all OMAP4+ SoCs too.
>
>> allow direct access to the SCL and SDA pins. In addition to ST_EN, we
>> need to set the TMODE to 0b11 (Loop back & SDA/SCL IO mode select).
>> Also, as the reset values of SCL_O and SDA_O are 0 (which means "drive
>> low level"), we need to set them to 1 (which means "high-impedance") to
>> avoid unwanted changes on the pins.
>>
>> As a precaution, reset all these bits to their default values after
>> recovery is complete.
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
>>
>> Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
>> ---
>> drivers/i2c/busses/i2c-omap.c | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>>
>> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
>> index d1c22e3fdd14..fc9bf7f30e35 100644
>> --- a/drivers/i2c/busses/i2c-omap.c
>> +++ b/drivers/i2c/busses/i2c-omap.c
>> @@ -1247,7 +1247,14 @@ static void omap_i2c_prepare_recovery(struct i2c_adapter *adap)
>> u32 reg;
>>
>> reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
>> + /* enable test mode */
>> reg |= OMAP_I2C_SYSTEST_ST_EN;
>> + /* select SDA/SCL IO mode */
>> + reg |= 3 << OMAP_I2C_SYSTEST_TMODE_SHIFT;
>> + /* set SCL to high-impedance state (reset value is 0) */
>> + reg |= OMAP_I2C_SYSTEST_SCL_O;
>> + /* set SDA to high-impedance state (reset value is 0) */
>> + reg |= OMAP_I2C_SYSTEST_SDA_O;
>> omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
>> }
>>
>> @@ -1257,7 +1264,11 @@ static void omap_i2c_unprepare_recovery(struct i2c_adapter *adap)
>> u32 reg;
>>
>> reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
>> + /* restore reset values */
>> reg &= ~OMAP_I2C_SYSTEST_ST_EN;
>> + reg &= ~OMAP_I2C_SYSTEST_TMODE_MASK;
>> + reg &= ~OMAP_I2C_SYSTEST_SCL_O;
>> + reg &= ~OMAP_I2C_SYSTEST_SDA_O;
>> omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
>> }
>>
>> --
>> 2.1.4
>>
--
regards,
-grygorii
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] i2c: omap: fix bus recovery setup
2015-07-14 12:10 ` Grygorii Strashko
@ 2015-07-14 12:12 ` Wolfram Sang
2015-07-29 10:27 ` Jan Lübbe
0 siblings, 1 reply; 8+ messages in thread
From: Wolfram Sang @ 2015-07-14 12:12 UTC (permalink / raw
To: linux-arm-kernel
On Tue, Jul 14, 2015 at 03:10:01PM +0300, Grygorii Strashko wrote:
> Hi Wolfram,
>
> On 07/14/2015 02:10 PM, Wolfram Sang wrote:
> > On Wed, Jul 08, 2015 at 04:35:27PM +0200, Jan Luebbe wrote:
> >> At least on the AM335x, enabling OMAP_I2C_SYSTEST_ST_EN is not enough to
> >
> > Felipe: it seems you did not need this; is this AM335x specific?
>
> We need it (Felipe's reply can be delayed).
So, how did it work for him?
> It's not AM335x specific. TMODE has to be configured for all OMAP4+ SoCs too.
Okay, thanks for the stepping in!
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^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] i2c: omap: fix bus recovery setup
2015-07-14 12:12 ` Wolfram Sang
@ 2015-07-29 10:27 ` Jan Lübbe
2015-07-31 10:49 ` Wolfram Sang
0 siblings, 1 reply; 8+ messages in thread
From: Jan Lübbe @ 2015-07-29 10:27 UTC (permalink / raw
To: linux-arm-kernel
On Di, 2015-07-14 at 14:12 +0200, Wolfram Sang wrote:
> On Tue, Jul 14, 2015 at 03:10:01PM +0300, Grygorii Strashko wrote:
> > Hi Wolfram,
> >
> > On 07/14/2015 02:10 PM, Wolfram Sang wrote:
> > > On Wed, Jul 08, 2015 at 04:35:27PM +0200, Jan Luebbe wrote:
> > >> At least on the AM335x, enabling OMAP_I2C_SYSTEST_ST_EN is not enough to
> > >
> > > Felipe: it seems you did not need this; is this AM335x specific?
> >
> > We need it (Felipe's reply can be delayed).
>
> So, how did it work for him?
>
> > It's not AM335x specific. TMODE has to be configured for all OMAP4+ SoCs too.
>
> Okay, thanks for the stepping in!
Wolfram, will you pick this as-is?
Regards,
Jan
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] i2c: omap: fix bus recovery setup
2015-07-29 10:27 ` Jan Lübbe
@ 2015-07-31 10:49 ` Wolfram Sang
0 siblings, 0 replies; 8+ messages in thread
From: Wolfram Sang @ 2015-07-31 10:49 UTC (permalink / raw
To: linux-arm-kernel
On Wed, Jul 29, 2015 at 12:27:30PM +0200, Jan L?bbe wrote:
> On Di, 2015-07-14 at 14:12 +0200, Wolfram Sang wrote:
> > On Tue, Jul 14, 2015 at 03:10:01PM +0300, Grygorii Strashko wrote:
> > > Hi Wolfram,
> > >
> > > On 07/14/2015 02:10 PM, Wolfram Sang wrote:
> > > > On Wed, Jul 08, 2015 at 04:35:27PM +0200, Jan Luebbe wrote:
> > > >> At least on the AM335x, enabling OMAP_I2C_SYSTEST_ST_EN is not enough to
> > > >
> > > > Felipe: it seems you did not need this; is this AM335x specific?
> > >
> > > We need it (Felipe's reply can be delayed).
> >
> > So, how did it work for him?
> >
> > > It's not AM335x specific. TMODE has to be configured for all OMAP4+ SoCs too.
> >
> > Okay, thanks for the stepping in!
>
> Wolfram, will you pick this as-is?
Yes, I was hoping for an answer to my above question to get a better
understanding, but we can still apply the patches meanwhile.
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^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] i2c: omap: fix bus recovery setup
2015-07-08 14:35 [PATCH] i2c: omap: fix bus recovery setup Jan Luebbe
2015-07-12 15:32 ` Alexander Sverdlin
2015-07-14 11:10 ` Wolfram Sang
@ 2015-07-31 10:51 ` Wolfram Sang
2 siblings, 0 replies; 8+ messages in thread
From: Wolfram Sang @ 2015-07-31 10:51 UTC (permalink / raw
To: linux-arm-kernel
On Wed, Jul 08, 2015 at 04:35:27PM +0200, Jan Luebbe wrote:
> At least on the AM335x, enabling OMAP_I2C_SYSTEST_ST_EN is not enough to
> allow direct access to the SCL and SDA pins. In addition to ST_EN, we
> need to set the TMODE to 0b11 (Loop back & SDA/SCL IO mode select).
> Also, as the reset values of SCL_O and SDA_O are 0 (which means "drive
> low level"), we need to set them to 1 (which means "high-impedance") to
> avoid unwanted changes on the pins.
>
> As a precaution, reset all these bits to their default values after
> recovery is complete.
>
> Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
Applied to for-current, thanks!
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2015-07-08 14:35 [PATCH] i2c: omap: fix bus recovery setup Jan Luebbe
2015-07-12 15:32 ` Alexander Sverdlin
2015-07-14 11:10 ` Wolfram Sang
2015-07-14 12:10 ` Grygorii Strashko
2015-07-14 12:12 ` Wolfram Sang
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