[U-Boot] [PATCH 3/4] i2c: dm: Record maximum id of devices before probing devices

[Simon Glass]

Hi Michal,

On Fri, 18 Jan 2019 at 08:13, Michal Simek <michal.simek at xilinx.com> wrote:
>
> There is a need to find out the first free i2c ID which can be used for
> i2s buses (including i2c buses connected to i2c mux). Do it early in
> init and share this variable with other i2c classes for uniq bus
> identification.
>
> Signed-off-by: Michal Simek <michal.simek at xilinx.com>
> ---
>
>  drivers/i2c/i2c-uclass.c | 19 +++++++++++++++++++
>  include/i2c.h            |  3 +++
>  2 files changed, 22 insertions(+)
>
> diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c
> index 975318e5f254..aaece115f02f 100644
> --- a/drivers/i2c/i2c-uclass.c
> +++ b/drivers/i2c/i2c-uclass.c
> @@ -23,6 +23,8 @@ enum {
>         PIN_COUNT,
>  };
>
> +int i2c_highest_id = -1;
> +
>  /* Useful debugging function */
>  void i2c_dump_msgs(struct i2c_msg *msg, int nmsgs)
>  {
> @@ -619,10 +621,27 @@ static int i2c_child_post_bind(struct udevice *dev)
>  #endif
>  }
>
> +int i2c_uclass_init(struct uclass *class)
> +{
> +#ifdef CONFIG_OF_LIVE
> +       int ret;
> +
> +       ret = of_alias_get_highest_id("i2c");
> +       if (ret >= 0)
> +               i2c_highest_id = ret;
> +#else
> +       i2c_highest_id = fdtdec_get_alias_highest_id(gd->fdt_blob, "i2c");
> +#endif

This should call dev_read_alias_highest_id() or similar, which does
the logic you have here.

> +       debug("%s: i2c highest_id %d\n", __func__, i2c_highest_id);
> +
> +       return 0;
> +}
> +
>  UCLASS_DRIVER(i2c) = {
>         .id             = UCLASS_I2C,
>         .name           = "i2c",
>         .flags          = DM_UC_FLAG_SEQ_ALIAS,
> +       .init           = i2c_uclass_init,
>  #if CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)
>         .post_bind      = dm_scan_fdt_dev,
>  #endif
> diff --git a/include/i2c.h b/include/i2c.h
> index ccffc1955275..c69e26deaeed 100644
> --- a/include/i2c.h
> +++ b/include/i2c.h
> @@ -16,6 +16,9 @@
>  #ifndef _I2C_H_
>  #define _I2C_H_
>
> +/* Stores maximum highest i2c alias number */
> +extern int i2c_highest_id;

This should be in uclass-private data, not a global.

But also I feel that the behaviour needs to be consistent for all
U-Boot buses, not just I2C. So can we modify the existing core DM code
instead? I think a change to uclass_resolve_seq() might be enough.

> +
>  /*
>   * For now there are essentially two parts to this file - driver model
>   * here at the top, and the older code below (with CONFIG_SYS_I2C being
> --
> 1.9.1
>

Regards,
Simon