nvmem: core: add per-cell post processing

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: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20230404172148.82422-17-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 49b4bbaf59e8b4799eac0c6d33582223c8018ba8..0708f9f2789882e7c73a0f9c5b03a3fc64224969 100644 (file)
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -54,6 +54,7 @@ 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;
@@ -470,6 +471,7 @@ 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;
@@ -1563,6 +1565,13 @@ 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);
@@ -1671,6 +1680,14 @@ 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 535c5f9f330985f1449c4904d9901f412d3fbad7..3bfc23553a9e87e25546c6d380b22a0fe2382c09 100644 (file)
--- 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;
 };
 
 /**