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

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Date:   Thu, 16 Jun 2022 14:02:13 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Dinh Nguyen <dinguyen@...nel.org>
Cc:     jarkko.nikula@...ux.intel.com, mika.westerberg@...ux.intel.com,
        robh+dt@...nel.org, krzk+dt@...nel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCHv4 1/2] i2c: designware: introduce a custom scl recovery
 for SoCFPGA platforms

On Wed, Jun 15, 2022 at 02:12:13PM -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().

Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

(yes, assuming stray change goes away)

> Signed-off-by: Dinh Nguyen <dinguyen@...nel.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;
>  }
>  
> +
>  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);
> -- 
> 2.25.1
> 

-- 
With Best Regards,
Andy Shevchenko