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SubjectRe: [PATCH v1 07/14] nvmem: core: add per-cell post processing
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On 25/08/2022 22:44, Michael Walle wrote:
> Instead of relying on the name the consumer is using for the cell, like
> it is done for the nvmem .cell_post_process configuration parameter,
> provide a per-cell post processing hook. This can then be populated by
> the NVMEM provider (or the NVMEM layout) when adding the cell.
>
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---
> drivers/nvmem/core.c | 16 ++++++++++++++++
> include/linux/nvmem-consumer.h | 5 +++++
> 2 files changed, 21 insertions(+)
>
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index 5357fc378700..cbfbe6264e6c 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -52,6 +52,7 @@ struct nvmem_cell_entry {
> int bytes;
> int bit_offset;
> int nbits;
> + nvmem_cell_post_process_t post_process;


two post_processing callbacks for cells is confusing tbh, we could
totally move to use of cell->post_process.

one idea is to point cell->post_process to nvmem->cell_post_process
during cell creation time which should clean this up a bit.

Other option is to move to using layouts for every thing.

prefixing post_process with read should also make it explicit that this
callback is very specific to reads only.


> struct device_node *np;
> struct nvmem_device *nvmem;
> struct list_head node;
> @@ -468,6 +469,7 @@ static int nvmem_cell_info_to_nvmem_cell_entry_nodup(struct nvmem_device *nvmem,
> cell->offset = info->offset;
> cell->bytes = info->bytes;
> cell->name = info->name;
> + cell->post_process = info->post_process;
>
> cell->bit_offset = info->bit_offset;
> cell->nbits = info->nbits;
> @@ -1500,6 +1502,13 @@ static int __nvmem_cell_read(struct nvmem_device *nvmem,
> if (cell->bit_offset || cell->nbits)
> nvmem_shift_read_buffer_in_place(cell, buf);
>
> + if (cell->post_process) {
> + rc = cell->post_process(nvmem->priv, id, index,
> + cell->offset, buf, cell->bytes);
> + if (rc)
> + return rc;
> + }
> +
> if (nvmem->cell_post_process) {
> rc = nvmem->cell_post_process(nvmem->priv, id, index,
> cell->offset, buf, cell->bytes);
> @@ -1608,6 +1617,13 @@ static int __nvmem_cell_entry_write(struct nvmem_cell_entry *cell, void *buf, si
> (cell->bit_offset == 0 && len != cell->bytes))
> return -EINVAL;
>
> + /*
> + * Any cells which have a post_process hook are read-only because we
> + * cannot reverse the operation and it might affect other cells, too.
> + */
> + if (cell->post_process)
> + return -EINVAL;

Post process was always implicitly for reads only, this check should
also tie the loose ends of cell_post_processing callback.


--srini
> +
> if (cell->bit_offset || cell->nbits) {
> buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
> if (IS_ERR(buf))
> diff --git a/include/linux/nvmem-consumer.h b/include/linux/nvmem-consumer.h
> index 980f9c9ac0bc..761b8ef78adc 100644
> --- a/include/linux/nvmem-consumer.h
> +++ b/include/linux/nvmem-consumer.h
> @@ -19,6 +19,10 @@ struct device_node;
> struct nvmem_cell;
> struct nvmem_device;
>
> +/* duplicated from nvmem-provider.h */
> +typedef int (*nvmem_cell_post_process_t)(void *priv, const char *id, int index,
> + unsigned int offset, void *buf, size_t bytes);
> +
> struct nvmem_cell_info {
> const char *name;
> unsigned int offset;
> @@ -26,6 +30,7 @@ struct nvmem_cell_info {
> unsigned int bit_offset;
> unsigned int nbits;
> struct device_node *np;
> + nvmem_cell_post_process_t post_process;
> };
>
> /**

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