Re: [PATCH V3 1/2] mtd: allow getting MTD device associated with a specific DT node

Miquel Raynal
2022-06-13T14:04:23Z

Hi Rafał,

zajec5@gmail.com wrote on Sat, 11 Jun 2022 22:46:50 +0200:

> From: Rafał Miłecki <rafal@milecki.pl>
>
> MTD subsystem API allows interacting with MTD devices (e.g. reading,
> writing, handling bad blocks). So far a random driver could get MTD
> device only by its name (get_mtd_device_nm()). This change allows
> getting them also by a DT node.
>
> This API is required for drivers handling DT defined MTD partitions in a
> specific way (e.g. U-Boot (sub)partition with environment variables).
>
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> ---
> V3: First introduction of of_get_mtd_device_by_node()
>
> mtd maintainers: please let know how would you like this patch
> processed. Would that be OK for you to Review/Ack it and let it go
> through NVMEM tree?

Yes

> ---
> drivers/mtd/mtdcore.c | 28 ++++++++++++++++++++++++++++
> include/linux/mtd/mtd.h | 1 +
> 2 files changed, 29 insertions(+)
>
> diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
> index 9eb0680db312..7dc214271c85 100644
> --- a/drivers/mtd/mtdcore.c
> +++ b/drivers/mtd/mtdcore.c
> @@ -1154,6 +1154,34 @@ int __get_mtd_device(struct mtd_info *mtd)
> }
> EXPORT_SYMBOL_GPL(__get_mtd_device);
>
> +/**
> + * of_get_mtd_device_by_node - obtain an MTD device associated with a given node
> + *
> + * @np: device tree node
> + */
> +struct mtd_info *of_get_mtd_device_by_node(struct device_node *np)

Shall we try to use a more of-agnostic syntax or is it too complex here?

> +{
> + struct mtd_info *mtd = NULL;
> + struct mtd_info *tmp;
> + int err;
> +
> + mutex_lock(&mtd_table_mutex);
> +
> + err = -ENODEV;
> + mtd_for_each_device(tmp) {
> + if (mtd_get_of_node(tmp) == np) {
> + mtd = tmp;
> + err = __get_mtd_device(mtd);
> + break;
> + }
> + }
> +
> + mutex_unlock(&mtd_table_mutex);
> +
> + return err ? ERR_PTR(err) : mtd;
> +}
> +EXPORT_SYMBOL_GPL(of_get_mtd_device_by_node);
> +
> /**
> * get_mtd_device_nm - obtain a validated handle for an MTD device by
> * device name
> diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
> index 955aee14b0f7..6fc841ceef31 100644
> --- a/include/linux/mtd/mtd.h
> +++ b/include/linux/mtd/mtd.h
> @@ -677,6 +677,7 @@ extern int mtd_device_unregister(struct mtd_info *master);
> extern struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num);
> extern int __get_mtd_device(struct mtd_info *mtd);
> extern void __put_mtd_device(struct mtd_info *mtd);
> +extern struct mtd_info *of_get_mtd_device_by_node(struct device_node *np);
> extern struct mtd_info *get_mtd_device_nm(const char *name);
> extern void put_mtd_device(struct mtd_info *mtd);
>

Thanks,
Miquèl