Re: [PATCH 2/2] i2c-ocore: support 16 and 32-bit wide registers

[Shubhrajyoti Datta <omaplinuxkernel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hi,

On Tue, May 8, 2012 at 6:55 PM, Jayachandran C
<jayachandranc-oSioyQM9ZPnuBjGU1YDckgC/G2K4zDHf@public.gmane.org> wrote:
> From: Ganesan Ramalingam <ganesanr-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
>
> Some architectures supports only 16-bit or 32-bit read/write access
> to their iospace. Add a 'regwidth' platform and OF parameter which
> specifies the IO width to support these platforms.
>
> regwidth can be specified as 1, 2 or 4, and has a default value
> of 1 if it is unspecified.
>
> Signed-off-by: Ganesan Ramalingam <ganesanr-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
> Signed-off-by: Jayachandran C <jayachandranc-oSioyQM9ZPnuBjGU1YDckgC/G2K4zDHf@public.gmane.org>
> ---
>  drivers/i2c/busses/i2c-ocores.c |   32 ++++++++++++++++++++++++++++++--
>  include/linux/i2c-ocores.h      |    1 +
>  2 files changed, 31 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
> index ebd2700..1313145 100644
> --- a/drivers/i2c/busses/i2c-ocores.c
> +++ b/drivers/i2c/busses/i2c-ocores.c
> @@ -19,6 +19,9 @@
>  * - regstep         : size of device registers in bytes
>  * - clock-frequency : frequency of bus clock in Hz
>  *
> + * Optional properties:
> + * - regwidth        : io register width in bytes (1, 2 or 4)
> +
>  * Example:
>  *
>  *  i2c0: ocores@a0000000 {
> @@ -27,6 +30,7 @@
>  *              interrupts = <10>;
>  *
>  *              regstep = <1>;
> + *              regwidth = <1>;
>  *              clock-frequency = <20000000>;
>  *
>  * -- Devices connected on this I2C bus get
> @@ -60,6 +64,7 @@
>  struct ocores_i2c {
>        void __iomem *base;
>        int regstep;
> +       int regwidth;

Do we need it to be signed?

>        wait_queue_head_t wait;
>        struct i2c_adapter adap;
>        struct i2c_msg *msg;
> @@ -102,12 +107,22 @@ struct ocores_i2c {
>
>  static inline void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value)
>  {
> -       iowrite8(value, i2c->base + reg * i2c->regstep);
> +       if (i2c->regwidth == 4)
> +               iowrite32(value, i2c->base + reg * i2c->regstep);
> +       else if (i2c->regwidth == 2)
> +               iowrite16(value, i2c->base + reg * i2c->regstep);
> +       else
> +               iowrite8(value, i2c->base + reg * i2c->regstep);
>  }
>
>  static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg)
Shouldnt the return type also change?

>  {
> -       return ioread8(i2c->base + reg * i2c->regstep);
> +       if (i2c->regwidth == 4)
> +               return ioread32(i2c->base + reg * i2c->regstep);
> +       else if (i2c->regwidth == 2)
> +               return ioread16(i2c->base + reg * i2c->regstep);
> +       else
> +               return ioread8(i2c->base + reg * i2c->regstep);
>  }
>
>  static void ocores_process(struct ocores_i2c *i2c)
> @@ -267,6 +282,10 @@ static int ocores_i2c_of_probe(struct platform_device* pdev,
>        }
>        i2c->clock_khz = be32_to_cpup(val) / 1000;
>
> +       val = of_get_property(pdev->dev.of_node, "regwidth", NULL);
> +       if (val)
> +               i2c->regwidth = be32_to_cpup(val);
> +
>        return 0;
>  }
>  #else
> @@ -309,12 +328,21 @@ static int __devinit ocores_i2c_probe(struct platform_device *pdev)
>        pdata = pdev->dev.platform_data;
>        if (pdata) {
>                i2c->regstep = pdata->regstep;
> +               i2c->regwidth = pdata->regwidth;
>                i2c->clock_khz = pdata->clock_khz;
>        } else {
>                ret = ocores_i2c_of_probe(pdev, i2c);
>                if (ret)
>                        return ret;
>        }
> +       if (i2c->regwidth == 0)
> +               i2c->regwidth = 1;      /* not configured, use default */
> +       else if (i2c->regwidth != 1 && i2c->regwidth != 2 &&
> +                       i2c->regwidth != 4) {
> +               dev_err(&pdev->dev, "Invalid register width %d\n",
> +                       i2c->regwidth);
> +               return -EINVAL;
> +       }
>
>        ocores_init(i2c);
>
> diff --git a/include/linux/i2c-ocores.h b/include/linux/i2c-ocores.h
> index 4d5e57f..d1258ad 100644
> --- a/include/linux/i2c-ocores.h
> +++ b/include/linux/i2c-ocores.h
> @@ -13,6 +13,7 @@
>
>  struct ocores_i2c_platform_data {
>        u32 regstep;   /* distance between registers */
> +       u32 regwidth;  /* io read/write register witdth */
>        u32 clock_khz; /* input clock in kHz */
>        u8 num_devices; /* number of devices in the devices list */
>        struct i2c_board_info const *devices; /* devices connected to the bus */
> --
> 1.7.9.5
>
>
> --
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