[PATCH v4 1/2] dm: core: add function uclass_probe_all() to probe all devices

[Sean Anderson]

On 11/17/20 10:00 AM, Vabhav Sharma wrote:
> From: Vabhav Sharma <vabhav.sharma at nxp.com>
> 
> Support a common method to probe all devices associated with uclass.
> 
> This includes data structures and code for finding the first device and
> looping for remaining devices associated with uclasses (groups of devices
> with the same purpose, e.g. all SERIAL ports will be in the same uclass).
> 
> An example is SBSA compliant PL011 UART IP, where firmware does the serial
> port initialization and prepare uart device to let the kernel use it for
> sending and reveiving the characters.SERIAL uclass will use this function
> to initialize PL011 UART ports.
> 
> The feature is enabled with CONFIG_DM.
> 
> Signed-off-by: Vabhav Sharma <vabhav.sharma at nxp.com>
> Reviewed-by: Stefan Roese <sr at denx.de>
> Reviewed-by: Simon Glass <sjg at chromium.org>
> --
>   v4:
>   Incorporated review comments of Simon
>   Removed if (dev)..  conditional check
> 
>   v3:
>   Incorporated review comments of Stephan,Simon
>   Related discussion https://patchwork.ozlabs.org/project/uboot/patch/1601400
> 385-11854-1-git-send-email-vabhav.sharma at oss.nxp.com/
> ---
>  drivers/core/uclass.c | 16 ++++++++++++++++
>  include/dm/uclass.h   | 12 ++++++++++++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/drivers/core/uclass.c b/drivers/core/uclass.c
> index c3f1b73..a1dc8bb 100644
> --- a/drivers/core/uclass.c
> +++ b/drivers/core/uclass.c
> @@ -792,6 +792,22 @@ int uclass_pre_remove_device(struct udevice *dev)
>  }
>  #endif
>  
> +int uclass_probe_all(enum uclass_id id)
> +{
> +	struct udevice *dev;
> +	int ret;
> +
> +	ret = uclass_first_device(id, &dev);
> +	if (ret || !dev)
> +		return ret;
> +
> +	/* Scanning uclass to probe all devices */
> +	for (; dev; uclass_next_device(&dev))

You must check the return value of this function.

Also, I would suggest using a while loop instead of an empty for loop.

> +		;
> +
> +	return 0;
> +}
> +
>  UCLASS_DRIVER(nop) = {
>  	.id		= UCLASS_NOP,
>  	.name		= "nop",
> diff --git a/include/dm/uclass.h b/include/dm/uclass.h
> index 7188304..7ac0aaa 100644
> --- a/include/dm/uclass.h
> +++ b/include/dm/uclass.h
> @@ -381,6 +381,18 @@ int uclass_first_device_drvdata(enum uclass_id id, ulong driver_data,
>  int uclass_resolve_seq(struct udevice *dev);
>  
>  /**
> + * uclass_probe_all() - Probe all devices based on an uclass ID
> + *
> + * Every uclass is identified by an ID, a number from 0 to n-1 where n is
> + * the number of uclasses. This function probe all devices asocciated with

nit: probes associated

> + * a uclass by looking its ID.

nit: for its

AFAICT uclass_find_next_device walks the linked-list of devices in a
uclass, and does not care about the ID. So this documentation is
incorrect.

> + *
> + * @id: uclass ID to look up
> + * @return 0 if OK, other -ve on error
> + */
> +int uclass_probe_all(enum uclass_id id);
> +
> +/**
>   * uclass_id_foreach_dev() - Helper function to iteration through devices
>   *
>   * This creates a for() loop which works through the available devices in
>