Re: [PATCH v3 4/5] i2c: davinci: use bus recovery infrastructure

[Alexander Sverdlin <alexander.sverdlin@nokia.com>]

Hello Grygorii,

On 01/12/14 16:34, Grygorii Strashko wrote:
> This patch converts Davinci I2C driver to use I2C bus recovery
> infrastructure, introduced by commit 5f9296ba21b3 ("i2c: Add
> bus recovery infrastructure").
> 
> The i2c_bus_recovery_info is configured for Davinci I2C adapter
> only in case scl_pin is provided in platform data.
> 
> As the controller must be held in reset while doing so, the
> recovery routine must re-init the controller. Since this was already
> being done after each call to i2c_recover_bus, move those calls into
> the recovery_prepare/unprepare routines and as well.
> 
> CC: Sekhar Nori <nsekhar@ti.com>
> CC: Kevin Hilman <khilman@deeprootsystems.com>
> CC: Santosh Shilimkar <ssantosh@kernel.org>
> CC: Murali Karicheri <m-karicheri2@ti.com>
> Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
> ---
>  drivers/i2c/busses/i2c-davinci.c | 77 +++++++++++++++++++---------------------
>  1 file changed, 36 insertions(+), 41 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
> index 17e1203..00aed63 100644
> --- a/drivers/i2c/busses/i2c-davinci.c
> +++ b/drivers/i2c/busses/i2c-davinci.c
> @@ -133,43 +133,6 @@ static inline u16 davinci_i2c_read_reg(struct davinci_i2c_dev *i2c_dev, int reg)
>  	return readw_relaxed(i2c_dev->base + reg);
>  }
>  
> -/* Generate a pulse on the i2c clock pin. */
> -static void davinci_i2c_clock_pulse(unsigned int scl_pin)
> -{
> -	u16 i;
> -
> -	if (scl_pin) {
> -		/* Send high and low on the SCL line */
> -		for (i = 0; i < 9; i++) {
> -			gpio_set_value(scl_pin, 0);
> -			udelay(20);
> -			gpio_set_value(scl_pin, 1);
> -			udelay(20);
> -		}
> -	}
> -}
> -
> -/* This routine does i2c bus recovery as specified in the
> - * i2c protocol Rev. 03 section 3.16 titled "Bus clear"
> - */
> -static void davinci_i2c_recover_bus(struct davinci_i2c_dev *dev)
> -{
> -	u32 flag = 0;
> -	struct davinci_i2c_platform_data *pdata = dev->pdata;
> -
> -	dev_err(dev->dev, "initiating i2c bus recovery\n");
> -	/* Send NACK to the slave */
> -	flag = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
> -	flag |=  DAVINCI_I2C_MDR_NACK;
> -	/* write the data into mode register */
> -	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag);
> -	davinci_i2c_clock_pulse(pdata->scl_pin);
> -	/* Send STOP */
> -	flag = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
> -	flag |= DAVINCI_I2C_MDR_STP;
> -	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag);
> -}
> -
>  static inline void davinci_i2c_reset_ctrl(struct davinci_i2c_dev *i2c_dev,
>  								int val)
>  {
> @@ -267,6 +230,34 @@ static int i2c_davinci_init(struct davinci_i2c_dev *dev)
>  }
>  
>  /*
> + * This routine does i2c bus recovery by using i2c_generic_gpio_recovery
> + * which is provided by I2C Bus recovery infrastructure.
> + */
> +static void davinci_i2c_prepare_recovery(struct i2c_adapter *adap)
> +{
> +	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
> +
> +	/* Disable interrupts */
> +	davinci_i2c_write_reg(dev, DAVINCI_I2C_IMR_REG, 0);

I suppose, you don't need to disable IRQs if you reset the controller as the very next action.

> +
> +	/* put I2C into reset */
> +	davinci_i2c_reset_ctrl(dev, 0);
> +}
> +
> +static void davinci_i2c_unprepare_recovery(struct i2c_adapter *adap)
> +{
> +	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
> +
> +	i2c_davinci_init(dev);
> +}
> +
> +static struct i2c_bus_recovery_info davinci_i2c_gpio_recovery_info = {
> +	.recover_bus = i2c_generic_gpio_recovery,
> +	.prepare_recovery = davinci_i2c_prepare_recovery,
> +	.unprepare_recovery = davinci_i2c_unprepare_recovery,
> +};
> +
> +/*
>   * Waiting for bus not busy
>   */
>  static int i2c_davinci_wait_bus_not_busy(struct davinci_i2c_dev *dev,
> @@ -286,8 +277,7 @@ static int i2c_davinci_wait_bus_not_busy(struct davinci_i2c_dev *dev,
>  				return -ETIMEDOUT;
>  			} else {
>  				to_cnt = 0;
> -				davinci_i2c_recover_bus(dev);
> -				i2c_davinci_init(dev);
> +				i2c_recover_bus(&dev->adapter);
>  			}
>  		}
>  		if (allow_sleep)
> @@ -376,8 +366,7 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
>  						      dev->adapter.timeout);
>  	if (r == 0) {
>  		dev_err(dev->dev, "controller timed out\n");
> -		davinci_i2c_recover_bus(dev);
> -		i2c_davinci_init(dev);
> +		i2c_recover_bus(adap);
>  		dev->buf_len = 0;
>  		return -ETIMEDOUT;
>  	}
> @@ -721,6 +710,12 @@ static int davinci_i2c_probe(struct platform_device *pdev)
>  	adap->timeout = DAVINCI_I2C_TIMEOUT;
>  	adap->dev.of_node = pdev->dev.of_node;
>  
> +	if (dev->pdata->scl_pin) {
> +		adap->bus_recovery_info = &davinci_i2c_gpio_recovery_info;
> +		adap->bus_recovery_info->scl_gpio = dev->pdata->scl_pin;
> +		adap->bus_recovery_info->sda_gpio = dev->pdata->sda_pin;
> +	}
> +
>  	adap->nr = pdev->id;
>  	r = i2c_add_numbered_adapter(adap);
>  	if (r) {
> 

-- 
Best regards,
Alexander Sverdlin.