Hi Ahmad,

-----Original Message-----
From: Ahmad Fatoum <a.fatoum@pengutronix.de>
Sent: 2021年9月22日 19:37
To: Joakim Zhang <redacted>;
srinivas.kandagatla@linaro.org; robh+dt@kernel.org; shawnguo@kernel.org
Cc: devicetree@vger.kernel.org; dl-linux-imx <redacted>;
kernel@pengutronix.de; linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/6] nvmem: core: add nvmem cell post processing
callback

On 08.09.21 12:02, Joakim Zhang wrote:

quoted

From: Srinivas Kandagatla <redacted>

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.

quoted

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

it.

quoted

Signed-off-by: Srinivas Kandagatla <redacted>
Signed-off-by: Joakim Zhang <redacted>
---
 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)

quoted

 	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,

quoted

 	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,

quoted

 				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.

quoted

  * @reg_read:	Callback to read data.
  * @reg_write:	Callback to write data.
+ * @cell_read_callback: Callback for vendor specific post processing
+ of cell data

The member below is called cell_post_process

Good caught! Will fix it in V2. Thanks.

Best Regards,
Joakim Zhang

quoted

  * @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;

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