[PATCH 1/4] nvmem: core: add per-cell post processing

Rafał Miłecki
2023-02-22T17:23:31Z

From: Michael Walle <michael@walle.cc>

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>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
---
drivers/nvmem/core.c | 17 +++++++++++++++++
include/linux/nvmem-provider.h | 3 +++
2 files changed, 20 insertions(+)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 6783cd8478d7..c5c9a4654241 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 read_post_process;
struct device_node *np;
struct nvmem_device *nvmem;
struct list_head node;
@@ -465,6 +466,7 @@ 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->read_post_process = info->read_post_process;

cell->bit_offset = info->bit_offset;
cell->nbits = info->nbits;
@@ -1429,6 +1431,13 @@ 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->read_post_process) {
+ rc = cell->read_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);
@@ -1537,6 +1546,14 @@ 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 read_post_process hook are read-only because
+ * we cannot reverse the operation and it might affect other cells,
+ * too.
+ */
+ if (cell->read_post_process)
+ return -EINVAL;
+
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-provider.h b/include/linux/nvmem-provider.h
index b3c14ce87a65..f87fd64eee8f 100644
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -54,6 +54,8 @@ struct nvmem_keepout {
* @bit_offset: Bit offset if cell is smaller than a byte.
* @nbits: Number of bits.
* @np: Optional device_node pointer.
+ * @read_post_process: Callback for optional post processing of cell data
+ * on reads.
*/
struct nvmem_cell_info {
const char *name;
@@ -62,6 +64,7 @@ struct nvmem_cell_info {
unsigned int bit_offset;
unsigned int nbits;
struct device_node *np;
+ nvmem_cell_post_process_t read_post_process;
};

/**
--
2.34.1