[PATCH 3/6] nvmem: core: add nvmem cell post processing callback

From: Joakim Zhang
Date: Wed Sep 08 2021 - 06:04:04 EST


From: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>

Some NVMEM providers have certain nvmem cells encoded, which requires
post processing before actually using it.

For example mac-address is stored in either in ascii or delimited or reverse-order.

Having a post-process callback hook to provider drivers would enable them to
do this vendor specific post processing before nvmem consumers see it.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
---
drivers/nvmem/core.c | 9 +++++++++
include/linux/nvmem-provider.h | 5 +++++
2 files changed, 14 insertions(+)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 23c08dbaf45e..4f81a3adf081 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -38,6 +38,7 @@ struct nvmem_device {
unsigned int nkeepout;
nvmem_reg_read_t reg_read;
nvmem_reg_write_t reg_write;
+ nvmem_cell_post_process_t cell_post_process;
struct gpio_desc *wp_gpio;
void *priv;
};
@@ -797,6 +798,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
nvmem->type = config->type;
nvmem->reg_read = config->reg_read;
nvmem->reg_write = config->reg_write;
+ nvmem->cell_post_process = config->cell_post_process;
nvmem->keepout = config->keepout;
nvmem->nkeepout = config->nkeepout;
if (config->of_node)
@@ -1404,6 +1406,13 @@ static int __nvmem_cell_read(struct nvmem_device *nvmem,
if (cell->bit_offset || cell->nbits)
nvmem_shift_read_buffer_in_place(cell, buf);

+ if (nvmem->cell_post_process) {
+ rc = nvmem->cell_post_process(nvmem->priv, cell->type,
+ cell->offset, buf, cell->bytes);
+ if (rc)
+ return rc;
+ }
+
if (len)
*len = cell->bytes;

diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
index 104505e9028f..d980c79f9605 100644
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -19,6 +19,9 @@ typedef int (*nvmem_reg_read_t)(void *priv, unsigned int offset,
void *val, size_t bytes);
typedef int (*nvmem_reg_write_t)(void *priv, unsigned int offset,
void *val, size_t bytes);
+/* used for vendor specific post processing of cell data */
+typedef int (*nvmem_cell_post_process_t)(void *priv, int type, unsigned int offset,
+ void *buf, size_t bytes);

enum nvmem_type {
NVMEM_TYPE_UNKNOWN = 0,
@@ -62,6 +65,7 @@ struct nvmem_keepout {
* @no_of_node: Device should not use the parent's of_node even if it's !NULL.
* @reg_read: Callback to read data.
* @reg_write: Callback to write data.
+ * @cell_read_callback: Callback for vendor specific post processing of cell data
* @size: Device size.
* @word_size: Minimum read/write access granularity.
* @stride: Minimum read/write access stride.
@@ -92,6 +96,7 @@ struct nvmem_config {
bool no_of_node;
nvmem_reg_read_t reg_read;
nvmem_reg_write_t reg_write;
+ nvmem_cell_post_process_t cell_post_process;
int size;
int word_size;
int stride;
--
2.17.1