Re: [PATCH 2/2] i2c/designware: Provide optional i2c bus recovery function

[Shubhrajyoti Datta <omaplinuxkernel@xxxxxxxxx>]

On Fri, Feb 24, 2012 at 5:01 PM, Viresh Kumar <viresh.kumar@xxxxxx> wrote:
> From: Vincenzo Frascino <vincenzo.frascino@xxxxxx>
>
> Add optional i2c_recover_bus() function to the Synopsys DesignWare I2C adapter
> driver that performs i2c bus recovery after timeout. The scope of this routine
> is to define i2c bus recovery procedure as specified in the i2c protocol Rev. 03
> section 3.16 titled "Bus clear".
What do you do in the function ?

Could we have it in the driver file itself?

>
> Since the Designware I2C controller doesn't provide direct control over SDA and
> SCL lines hence the intent is to let platform try to recover the bus if they
> have the capability to take control of I2C pads and follow the recovery
> protocol.

So the function is passed in the pdata.
>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxx>
> Signed-off-by: Shiraz Hashim <shiraz.hashim@xxxxxx>
> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxx>
> ---
>  drivers/i2c/busses/i2c-designware-core.c    |    4 +++
>  drivers/i2c/busses/i2c-designware-core.h    |    3 +-
>  drivers/i2c/busses/i2c-designware-platdrv.c |    8 ++++++
>  include/linux/i2c/i2c-designware.h          |   33 +++++++++++++++++++++++++++
>  4 files changed, 47 insertions(+), 1 deletions(-)
>  create mode 100644 include/linux/i2c/i2c-designware.h
>
> diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
> index df87992..91d9357 100644
> --- a/drivers/i2c/busses/i2c-designware-core.c
> +++ b/drivers/i2c/busses/i2c-designware-core.c
> @@ -525,6 +525,10 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>        ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete, HZ);
>        if (ret == 0) {
>                dev_err(dev->dev, "controller timed out\n");
> +               if (dev->i2c_recover_bus) {
> +                       dev_info(dev->dev, "try i2c bus recovery\n");
> +                       dev->i2c_recover_bus(dev->recovery_data);
> +               }
>                i2c_dw_init(dev);
>                ret = -ETIMEDOUT;
>                goto done;
> diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
> index 02d1a2d..e2f3119 100644
> --- a/drivers/i2c/busses/i2c-designware-core.h
> +++ b/drivers/i2c/busses/i2c-designware-core.h
> @@ -34,7 +34,6 @@
>  #define DW_IC_CON_RESTART_EN           0x20
>  #define DW_IC_CON_SLAVE_DISABLE                0x40
>
> -
>  /**
>  * struct dw_i2c_dev - private i2c-designware data
>  * @dev: driver model device node
> @@ -88,6 +87,8 @@ struct dw_i2c_dev {
>        u32                     master_cfg;
>        unsigned int            tx_fifo_depth;
>        unsigned int            rx_fifo_depth;
> +       void                    (*i2c_recover_bus)(void *);
> +       void                    *recovery_data;
>  };
>
>  extern u32 dw_readl(struct dw_i2c_dev *dev, int offset);
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index c5ac2dc..2237398 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -29,6 +29,7 @@
>  #include <linux/module.h>
>  #include <linux/delay.h>
>  #include <linux/i2c.h>
> +#include <linux/i2c/i2c-designware.h>
>  #include <linux/clk.h>
>  #include <linux/errno.h>
>  #include <linux/sched.h>
> @@ -55,6 +56,7 @@ static int __devinit dw_i2c_probe(struct platform_device *pdev)
>        struct dw_i2c_dev *dev;
>        struct i2c_adapter *adap;
>        struct resource *mem, *ioarea;
> +       struct i2c_dw_pdata *pdata;
>        int irq, r;
>
>        /* NOTE: driver uses the static register mapping */
> @@ -98,6 +100,12 @@ static int __devinit dw_i2c_probe(struct platform_device *pdev)
>        }
>        clk_enable(dev->clk);
>
> +       pdata = dev_get_platdata(&pdev->dev);
> +       if (pdata && pdata->i2c_recover_bus) {
> +               dev->i2c_recover_bus = pdata->i2c_recover_bus;
> +               dev->recovery_data = &pdev;
> +       }
> +
>        dev->functionality =
>                I2C_FUNC_I2C |
>                I2C_FUNC_10BIT_ADDR |
> diff --git a/include/linux/i2c/i2c-designware.h b/include/linux/i2c/i2c-designware.h
> new file mode 100644
> index 0000000..e40ad85
> --- /dev/null
> +++ b/include/linux/i2c/i2c-designware.h
> @@ -0,0 +1,33 @@
> +/*
> + * Synopsys DesignWare I2C adapter driver's platform data
> + *
> + * Copyright (C) 2012 ST Microelectronics.
> + * Author: Vincenzo Frascino <vincenzo.frascino@xxxxxx>
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +#ifndef I2C_DESIGNWARE_H
> +#define I2C_DESIGNWARE_H
> +
> +#include <linux/platform_device.h>
> +
> +/* I2C Designware Platform Data */
> +struct i2c_dw_pdata {
> +       /*
> +        * The scope of this routine is to define i2c bus recovery procedure
> +        * as specified in the i2c protocol Rev. 03 section 3.16 titled
> +        * "Bus clear".
> +        * Its implementation is platform dependant.
> +        */
> +       void (*i2c_recover_bus)(void *);
> +};
> +
> +#endif /* I2C_DESIGNWARE_H */
> --
> 1.7.8.110.g4cb5d
>
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