[PATCHv3 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

[PATCHv3 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.

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().

Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
---
v3: simplify the function
    update commit message
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  | 12 ++++++++++++
 drivers/i2c/busses/i2c-designware-platdrv.c |  1 +
 3 files changed, 14 insertions(+)

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..502820b812a5 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -813,12 +813,24 @@ 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;
 
+	if ((dev->flags & MODEL_MASK) == MODEL_SOCFPGA) {
+		rinfo->recover_bus = i2c_socfpga_scl_recovery;
+		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);
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

[PATCHv3 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>
---
v3: no changes
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: [PATCHv3 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

[Andy Shevchenko]

On Mon, Jun 13, 2022 at 04:00:31PM -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.
> 
> 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().

Thanks for an update!
My comments below.

...

> +static int i2c_socfpga_scl_recovery(struct i2c_adapter *adap)
> +{
> +	i2c_dw_prepare_recovery(adap);
> +	i2c_dw_unprepare_recovery(adap);

Can we use

	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;

	bri->prepare_recovery(adap);
	bri->unprepare_recovery(adap);

> +	return 0;
> +}

instead and...

...

>  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;
>  
> +	if ((dev->flags & MODEL_MASK) == MODEL_SOCFPGA) {
> +		rinfo->recover_bus = i2c_socfpga_scl_recovery;
> +		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);

...this one to be transformed like (in a preparatory patch and in this one):

static int i2c_dw_init_socfpga_recovery_info(struct dw_i2c_dev *dev,
					     struct i2c_bus_recovery_info *rinfo)
{
	rinfo->recover_bus = i2c_socfpga_scl_recovery;
	return 0;
}

static int i2c_dw_init_generic_recovery_info(struct dw_i2c_dev *dev,
					     struct i2c_bus_recovery_info *rinfo)
{
	struct i2c_adapter *adap = &dev->adapter;
	struct gpio_desc *gpio;

	gpio = devm_gpiod_get_optional(dev->dev, "scl", GPIOD_OUT_HIGH);
	if (IS_ERR_OR_NULL(gpio))
		return PTR_ERR_OR_ZERO(gpio);

	rinfo->scl_gpiod = gpio;

	gpio = devm_gpiod_get_optional(dev->dev, "sda", GPIOD_IN);
	if (IS_ERR(gpio))
		return PTR_ERR(gpio);
	rinfo->sda_gpiod = gpio;

	rinfo->recover_bus = i2c_generic_scl_recovery;

	dev_info(dev->dev, "running with gpio recovery mode! scl%s",
		 rinfo->sda_gpiod ? ",sda" : "");

	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;
	int ret;

	switch (dev->flags & MODEL_MASK) {
	case MODEL_SOCFPGA:
		ret = i2c_dw_init_socfpga_recovery_info(dev, rinfo);
		break;
	default:
		ret = i2c_dw_init_generic_recovery_info(dev, rinfo);
		break;
	}
	if (ret)
		return ret;

	rinfo->prepare_recovery = i2c_dw_prepare_recovery;
	rinfo->unprepare_recovery = i2c_dw_unprepare_recovery;
	adap->bus_recovery_info = rinfo;

	return 0;
}

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCHv3 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

[Andy Shevchenko]

On Wed, Jun 15, 2022 at 01:18:55PM +0300, Andy Shevchenko wrote:
> On Mon, Jun 13, 2022 at 04:00:31PM -0500, Dinh Nguyen wrote:


The below won't fly, see my corrections below.

> static int i2c_dw_init_socfpga_recovery_info(struct dw_i2c_dev *dev,
> 					     struct i2c_bus_recovery_info *rinfo)
> {
> 	rinfo->recover_bus = i2c_socfpga_scl_recovery;
> 	return 0;

	return 1;

> }
> 
> static int i2c_dw_init_generic_recovery_info(struct dw_i2c_dev *dev,
> 					     struct i2c_bus_recovery_info *rinfo)
> {
> 	struct i2c_adapter *adap = &dev->adapter;
> 	struct gpio_desc *gpio;
> 
> 	gpio = devm_gpiod_get_optional(dev->dev, "scl", GPIOD_OUT_HIGH);
> 	if (IS_ERR_OR_NULL(gpio))
> 		return PTR_ERR_OR_ZERO(gpio);
> 
> 	rinfo->scl_gpiod = gpio;
> 
> 	gpio = devm_gpiod_get_optional(dev->dev, "sda", GPIOD_IN);
> 	if (IS_ERR(gpio))
> 		return PTR_ERR(gpio);
> 	rinfo->sda_gpiod = gpio;
> 
> 	rinfo->recover_bus = i2c_generic_scl_recovery;
> 
> 	dev_info(dev->dev, "running with gpio recovery mode! scl%s",
> 		 rinfo->sda_gpiod ? ",sda" : "");
> 
> 	return 0;

	return 1;

> }
> 
> 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;
> 	int ret;
> 
> 	switch (dev->flags & MODEL_MASK) {
> 	case MODEL_SOCFPGA:
> 		ret = i2c_dw_init_socfpga_recovery_info(dev, rinfo);
> 		break;
> 	default:
> 		ret = i2c_dw_init_generic_recovery_info(dev, rinfo);
> 		break;
> 	}
> 	if (ret)

	/* The recovery is optional, that's why 0 should be returned to the caller */
	if (ret <= 0)

> 		return ret;
> 
> 	rinfo->prepare_recovery = i2c_dw_prepare_recovery;
> 	rinfo->unprepare_recovery = i2c_dw_unprepare_recovery;
> 	adap->bus_recovery_info = rinfo;
> 
> 	return 0;
> }

-- 
With Best Regards,
Andy Shevchenko