Re: [PATCHv4 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

[Dinh Nguyen <dinguyen@kernel.org>]

On 6/15/22 14:12, 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().
> 
> Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
> ---
> v4: re-arrange code per Andy Shevchenko's recommendation
> 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  | 50 ++++++++++++++++++---
>   drivers/i2c/busses/i2c-designware-platdrv.c |  1 +
>   3 files changed, 46 insertions(+), 6 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..6b75a08a1c1f 100644
> --- a/drivers/i2c/busses/i2c-designware-master.c
> +++ b/drivers/i2c/busses/i2c-designware-master.c
> @@ -813,10 +813,26 @@ static void i2c_dw_unprepare_recovery(struct i2c_adapter *adap)
>   	i2c_dw_init_master(dev);
>   }
>   
> -static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
> +static int i2c_socfpga_scl_recovery(struct i2c_adapter *adap)
> +{
> +	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
> +
> +	bri->prepare_recovery(adap);
> +	bri->unprepare_recovery(adap);
> +
> +	return 0;
> +}
> +
> +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 1;
> +}
> +
> +static int i2c_dw_init_generic_recovery_info(struct dw_i2c_dev *dev,
> +					     struct i2c_bus_recovery_info *rinfo)
>   {
> -	struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
> -	struct i2c_adapter *adap = &dev->adapter;
>   	struct gpio_desc *gpio;
>   
>   	gpio = devm_gpiod_get_optional(dev->dev, "scl", GPIOD_OUT_HIGH);
> @@ -831,16 +847,38 @@ static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
>   	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" : "");
>   
> +	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 <= 0)
> +		return ret;
> +
> +	rinfo->prepare_recovery = i2c_dw_prepare_recovery;
> +	rinfo->unprepare_recovery = i2c_dw_unprepare_recovery;
> +	adap->bus_recovery_info = rinfo;
> +
>   	return 0;
>   }
>   
> +

Sorry for this stray newline, let me if you need me to send a v5?

>   static int amd_i2c_adap_quirk(struct dw_i2c_dev *dev)
>   {
>   	struct i2c_adapter *adap = &dev->adapter;
> 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);