Re: [PATCH 1/2] i2c-s3c2410: Rework device type handling

Thomas Abraham
2012-03-12T05:58:16Z

On 9 March 2012 22:34, Karol Lewandowski <k.lewandowsk@samsung.com> wrote:
> Reorganize driver a bit to better handle device tree-based systems:
>
>  - move machine type to driver's private structure instead of
>   quering platform device variants in runtime
>
>  - replace s3c24xx_i2c_type enum with plain unsigned int that can
>   hold not only device type but also hw revision-specific quirks
>
> Signed-off-by: Karol Lewandowski <k.lewandowsk@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
>  drivers/i2c/busses/i2c-s3c2410.c |   56 +++++++++++++------------------------
>  1 files changed, 20 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
> index 737f721..5b400c6 100644
> --- a/drivers/i2c/busses/i2c-s3c2410.c
> +++ b/drivers/i2c/busses/i2c-s3c2410.c
> @@ -44,8 +44,12 @@
>  #include <plat/regs-iic.h>
>  #include <plat/iic.h>
>
> -/* i2c controller state */
> +/* type */
> +#define TYPE_BITS              0x000000ff
> +#define TYPE_S3C2410           0x00000001
> +#define TYPE_S3C2440           0x00000002
>
> +/* i2c controller state */
>  enum s3c24xx_i2c_state {
>        STATE_IDLE,
>        STATE_START,
> @@ -54,14 +58,10 @@ enum s3c24xx_i2c_state {
>        STATE_STOP
>  };
>
> -enum s3c24xx_i2c_type {
> -       TYPE_S3C2410,
> -       TYPE_S3C2440,
> -};
> -
>  struct s3c24xx_i2c {
>        spinlock_t              lock;
>        wait_queue_head_t       wait;
> +       unsigned int            type;
>        unsigned int            suspended:1;
>
>        struct i2c_msg          *msg;
> @@ -88,28 +88,6 @@ struct s3c24xx_i2c {
>  #endif
>  };
>
> -/* default platform data removed, dev should always carry data. */
> -
> -/* s3c24xx_i2c_is2440()
> - *
> - * return true is this is an s3c2440
> -*/
> -
> -static inline int s3c24xx_i2c_is2440(struct s3c24xx_i2c *i2c)
> -{
> -       struct platform_device *pdev = to_platform_device(i2c->dev);
> -       enum s3c24xx_i2c_type type;
> -
> -#ifdef CONFIG_OF
> -       if (i2c->dev->of_node)
> -               return of_device_is_compatible(i2c->dev->of_node,
> -                               "samsung,s3c2440-i2c");
> -#endif
> -
> -       type = platform_get_device_id(pdev)->driver_data;
> -       return type == TYPE_S3C2440;
> -}
> -
>  /* s3c24xx_i2c_master_complete
>  *
>  * complete the message and wake up the caller, using the given return code,
> @@ -676,7 +654,7 @@ static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
>
>        writel(iiccon, i2c->regs + S3C2410_IICCON);
>
> -       if (s3c24xx_i2c_is2440(i2c)) {
> +       if (i2c->type & TYPE_S3C2440) {

This should be changed to
if (i2c->type == TYPE_S3C2440)

>                unsigned long sda_delay;
>
>                if (pdata->sda_delay) {
> @@ -847,6 +825,8 @@ static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
>  }
>
>  #ifdef CONFIG_OF
> +static const struct of_device_id s3c24xx_i2c_match[];
> +
>  /* s3c24xx_i2c_parse_dt
>  *
>  * Parse the device tree node and retreive the platform data.
> @@ -856,11 +836,16 @@ static void
>  s3c24xx_i2c_parse_dt(struct device_node *np, struct s3c24xx_i2c *i2c)
>  {
>        struct s3c2410_platform_i2c *pdata = i2c->pdata;
> +       const struct of_device_id *match;
>
>        if (!np)
>                return;
>
>        pdata->bus_num = -1; /* i2c bus number is dynamically assigned */
> +
> +       match = of_match_node(&s3c24xx_i2c_match[0], np);

This could be
match = of_match_node(s3c24xx_i2c_match, np);

> +       i2c->type = (unsigned int)match->data;
> +

This function (s3c24xx_i2c_parse_dt) is intended to retrieve the data
from i2c device node. It would be better to not add the determination
of the i2c type inside this function.

>        of_property_read_u32(np, "samsung,i2c-sda-delay", &pdata->sda_delay);
>        of_property_read_u32(np, "samsung,i2c-slave-addr", &pdata->slave_addr);
>        of_property_read_u32(np, "samsung,i2c-max-bus-freq",
> @@ -906,9 +891,10 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev)
>                goto err_noclk;
>        }
>
> -       if (pdata)
> +       if (pdata) {
>                memcpy(i2c->pdata, pdata, sizeof(*pdata));
> -       else
> +               i2c->type = platform_get_device_id(pdev)->driver_data;
> +       } else
>                s3c24xx_i2c_parse_dt(pdev->dev.of_node, i2c);

It would be better to move the task of retrieving the driver data to a
separate function. An example of this listed below (copied from the
samsung uart driver).

static inline struct s3c24xx_serial_drv_data *s3c24xx_get_driver_data(
struct platform_device *pdev)
{
#ifdef CONFIG_OF
if (pdev->dev.of_node) {
const struct of_device_id *match;
match = of_match_node(s3c24xx_uart_dt_match, pdev->dev.of_node);
return (struct s3c24xx_serial_drv_data *)match->data;
}
#endif
return (struct s3c24xx_serial_drv_data *)
platform_get_device_id(pdev)->driver_data;
}

>
>        strlcpy(i2c->adap.name, "s3c2410-i2c", sizeof(i2c->adap.name));
> @@ -1123,13 +1109,11 @@ MODULE_DEVICE_TABLE(platform, s3c24xx_driver_ids);
>
>  #ifdef CONFIG_OF
>  static const struct of_device_id s3c24xx_i2c_match[] = {
> -       { .compatible = "samsung,s3c2410-i2c" },
> -       { .compatible = "samsung,s3c2440-i2c" },
> +       { .compatible = "samsung,s3c2410-i2c", .data = (void *)TYPE_S3C2410 },
> +       { .compatible = "samsung,s3c2440-i2c", .data = (void *)TYPE_S3C2440 },
>        {},
>  };
>  MODULE_DEVICE_TABLE(of, s3c24xx_i2c_match);
> -#else
> -#define s3c24xx_i2c_match NULL
>  #endif
>
>  static struct platform_driver s3c24xx_i2c_driver = {
> @@ -1140,7 +1124,7 @@ static struct platform_driver s3c24xx_i2c_driver = {
>                .owner  = THIS_MODULE,
>                .name   = "s3c-i2c",
>                .pm     = S3C24XX_DEV_PM_OPS,
> -               .of_match_table = s3c24xx_i2c_match,
> +               .of_match_table = of_match_ptr(s3c24xx_i2c_match),

Should this change be a separate patch?

Thanks,
Thomas.