[PATCHv2 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

[PATCHv2 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

[Dinh Nguyen]

The I2C pins on the SoCFPGA platforms do not go through a GPIO module,
thus cannot be recovered by the default method of by doing a GPIO access.
Only a reset of the I2C IP block can a recovery be successful.

Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
---
v2: remove change to MODEL_MASK
    s/i2c_custom_scl_recovery/i2c_socfpga_scl_recovery
---
 drivers/i2c/busses/i2c-designware-core.h    |  1 +
 drivers/i2c/busses/i2c-designware-master.c  | 19 +++++++++++++++++--
 drivers/i2c/busses/i2c-designware-platdrv.c |  1 +
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 70b80e710990..7b22ec1d6a96 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -303,6 +303,7 @@ struct dw_i2c_dev {
 #define MODEL_MSCC_OCELOT	BIT(8)
 #define MODEL_BAIKAL_BT1	BIT(9)
 #define MODEL_AMD_NAVI_GPU	BIT(10)
+#define MODEL_SOCFPGA		BIT(11)
 #define MODEL_MASK		GENMASK(11, 8)
 
 /*
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index 44a94b225ed8..843d4bbab9cc 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -813,12 +813,29 @@ static void i2c_dw_unprepare_recovery(struct i2c_adapter *adap)
 	i2c_dw_init_master(dev);
 }
 
+static int i2c_socfpga_scl_recovery(struct i2c_adapter *adap)
+{
+	i2c_dw_prepare_recovery(adap);
+	i2c_dw_unprepare_recovery(adap);
+	return 0;
+}
+
 static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
 {
 	struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
 	struct i2c_adapter *adap = &dev->adapter;
 	struct gpio_desc *gpio;
 
+	switch (dev->flags & MODEL_MASK) {
+	case MODEL_SOCFPGA:
+		rinfo->recover_bus = i2c_socfpga_scl_recovery;
+		break;
+	default:
+		rinfo->recover_bus = i2c_generic_scl_recovery;
+		break;
+	}
+	adap->bus_recovery_info = rinfo;
+
 	gpio = devm_gpiod_get_optional(dev->dev, "scl", GPIOD_OUT_HIGH);
 	if (IS_ERR_OR_NULL(gpio))
 		return PTR_ERR_OR_ZERO(gpio);
@@ -830,10 +847,8 @@ static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
 		return PTR_ERR(gpio);
 	rinfo->sda_gpiod = gpio;
 
-	rinfo->recover_bus = i2c_generic_scl_recovery;
 	rinfo->prepare_recovery = i2c_dw_prepare_recovery;
 	rinfo->unprepare_recovery = i2c_dw_unprepare_recovery;
-	adap->bus_recovery_info = rinfo;
 
 	dev_info(dev->dev, "running with gpio recovery mode! scl%s",
 		 rinfo->sda_gpiod ? ",sda" : "");
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 70ade5306e45..b33e015e6732 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -153,6 +153,7 @@ static const struct of_device_id dw_i2c_of_match[] = {
 	{ .compatible = "snps,designware-i2c", },
 	{ .compatible = "mscc,ocelot-i2c", .data = (void *)MODEL_MSCC_OCELOT },
 	{ .compatible = "baikal,bt1-sys-i2c", .data = (void *)MODEL_BAIKAL_BT1 },
+	{ .compatible = "intel,socfpga-i2c", .data = (void *)MODEL_SOCFPGA },
 	{},
 };
 MODULE_DEVICE_TABLE(of, dw_i2c_of_match);
-- 
2.25.1

[PATCHv2 2/2] dt-bindings: i2c: dw: Add Intel's SoCFPGA I2C controller

[Dinh Nguyen]

The I2C pins on Intel's SoCFPGA platform are not connected to GPIOs and
thus cannot be recovered by the standard GPIO method.

Document the "intel,socfpga-i2c" binding.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
---
v2: Added Acked-by
---
 Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml b/Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml
index d9293c57f573..a130059e97ab 100644
--- a/Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml
+++ b/Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml
@@ -33,6 +33,8 @@ properties:
           - const: snps,designware-i2c
       - description: Baikal-T1 SoC System I2C controller
         const: baikal,bt1-sys-i2c
+      - description: Intel's SoCFPGA I2C controller
+        const: intel,socfpga-i2c
 
   reg:
     minItems: 1
-- 
2.25.1

Re: [PATCHv2 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

[Andy Shevchenko]

On Tue, May 24, 2022 at 08:54:40AM -0500, Dinh Nguyen wrote:
> The I2C pins on the SoCFPGA platforms do not go through a GPIO module,
> thus cannot be recovered by the default method of by doing a GPIO access.
> Only a reset of the I2C IP block can a recovery be successful.

Better now, but see my additional comments.

...

> +	switch (dev->flags & MODEL_MASK) {
> +	case MODEL_SOCFPGA:
> +		rinfo->recover_bus = i2c_socfpga_scl_recovery;
> +		break;
> +	default:
> +		rinfo->recover_bus = i2c_generic_scl_recovery;
> +		break;
> +	}

> +	adap->bus_recovery_info = rinfo;

Usually we do not assign the pointer while data structure is incomplete.
That's said, please leave this line as it was.

On top of that, why you can't move the above switch to the place where old
function was assigned?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCHv2 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

[Dinh Nguyen]

On 5/24/22 11:43, Andy Shevchenko wrote:
> On Tue, May 24, 2022 at 08:54:40AM -0500, Dinh Nguyen wrote:
>> The I2C pins on the SoCFPGA platforms do not go through a GPIO module,
>> thus cannot be recovered by the default method of by doing a GPIO access.
>> Only a reset of the I2C IP block can a recovery be successful.
> 
> Better now, but see my additional comments.
> 
> ...
> 
>> +	switch (dev->flags & MODEL_MASK) {
>> +	case MODEL_SOCFPGA:
>> +		rinfo->recover_bus = i2c_socfpga_scl_recovery;
>> +		break;
>> +	default:
>> +		rinfo->recover_bus = i2c_generic_scl_recovery;
>> +		break;
>> +	}
> 
>> +	adap->bus_recovery_info = rinfo;
> 
> Usually we do not assign the pointer while data structure is incomplete.
> That's said, please leave this line as it was.
> 
> On top of that, why you can't move the above switch to the place where old
> function was assigned?
> 

I have to put the switch statement before the call to 
devm_gpiod_get_optional(), otherwise the recover_bus function pointer 
will not get set.

Dinh

Re: [PATCHv2 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

[Dinh Nguyen]

On 5/24/22 11:43, Andy Shevchenko wrote:
> On Tue, May 24, 2022 at 08:54:40AM -0500, Dinh Nguyen wrote:
>> The I2C pins on the SoCFPGA platforms do not go through a GPIO module,
>> thus cannot be recovered by the default method of by doing a GPIO access.
>> Only a reset of the I2C IP block can a recovery be successful.
> 
> Better now, but see my additional comments.
> 
> ...
> 
>> +	switch (dev->flags & MODEL_MASK) {
>> +	case MODEL_SOCFPGA:
>> +		rinfo->recover_bus = i2c_socfpga_scl_recovery;
>> +		break;
>> +	default:
>> +		rinfo->recover_bus = i2c_generic_scl_recovery;
>> +		break;
>> +	}
> 
>> +	adap->bus_recovery_info = rinfo;
> 
> Usually we do not assign the pointer while data structure is incomplete.
> That's said, please leave this line as it was.
> 
> On top of that, why you can't move the above switch to the place where old
> function was assigned?
> 

The reason is the assignment of the recover_bus needs to get done before 
the call to devm_gpiod_get_optional(), otherwise, the assignment is not 
taking place because of an error after returning from 
devm_gpiod_get_optional().

Dinh

Re: [PATCHv2 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

[Andy Shevchenko]

On Wed, Jun 01, 2022 at 08:48:07AM -0500, Dinh Nguyen wrote:
> On 5/24/22 11:43, Andy Shevchenko wrote:
> > On Tue, May 24, 2022 at 08:54:40AM -0500, Dinh Nguyen wrote:

...

> > > +	switch (dev->flags & MODEL_MASK) {
> > > +	case MODEL_SOCFPGA:
> > > +		rinfo->recover_bus = i2c_socfpga_scl_recovery;
> > > +		break;
> > > +	default:
> > > +		rinfo->recover_bus = i2c_generic_scl_recovery;
> > > +		break;
> > > +	}
> > 
> > > +	adap->bus_recovery_info = rinfo;
> > 
> > Usually we do not assign the pointer while data structure is incomplete.
> > That's said, please leave this line as it was.
> > 
> > On top of that, why you can't move the above switch to the place where old
> > function was assigned?
> 
> The reason is the assignment of the recover_bus needs to get done before the
> call to devm_gpiod_get_optional(), otherwise, the assignment is not taking
> place because of an error after returning from devm_gpiod_get_optional().

Update commit message accordingly then.

Also consider moving GPIO request part in the code, maybe it will bring better
looking / grouped code. Try and see, then choose the best one.

-- 
With Best Regards,
Andy Shevchenko