From: Michael Walle <mich...@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 <mich...@walle.cc>
Signed-off-by: Srinivas Kandagatla <srinivas.kandaga...@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

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