Hi,
Am 2022-08-30 15:37, schrieb Srinivas Kandagatla:
On 25/08/2022 22:44, Michael Walle wrote:
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@xxxxxxxx>
---
drivers/nvmem/core.c | 16 ++++++++++++++++
include/linux/nvmem-consumer.h | 5 +++++
2 files changed, 21 insertions(+)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 5357fc378700..cbfbe6264e6c 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 post_process;
two post_processing callbacks for cells is confusing tbh, we could
totally move to use of cell->post_process.
one idea is to point cell->post_process to nvmem->cell_post_process
during cell creation time which should clean this up a bit.
You'll then trigger the read-only check below for all the cells
if nvmem->cell_post_process is set.
Other option is to move to using layouts for every thing.
As mentioned in a previous reply, I can't see how it could be
achieved. The problem here is that:
(1) the layout isn't creating the cells, the OF parser is
(2) even if we would create the cells, we wouldn't know
which cell needs the post_process. So we are back to
the situation above, were we have to add it to all
the cells, making them read-only. [We depend on the
name of the nvmem-consumer to apply the hook.
prefixing post_process with read should also make it explicit that
this callback is very specific to reads only.
good idea.
-michael
struct device_node *np;
struct nvmem_device *nvmem;
struct list_head node;
@@ -468,6 +469,7 @@ 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->post_process = info->post_process;
cell->bit_offset = info->bit_offset;
cell->nbits = info->nbits;
@@ -1500,6 +1502,13 @@ 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->post_process) {
+ rc = cell->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);
@@ -1608,6 +1617,13 @@ 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 post_process hook are read-only because we
+ * cannot reverse the operation and it might affect other cells,
too.
+ */
+ if (cell->post_process)
+ return -EINVAL;
Post process was always implicitly for reads only, this check should
also tie the loose ends of cell_post_processing callback.
--srini
+
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-consumer.h
b/include/linux/nvmem-consumer.h
index 980f9c9ac0bc..761b8ef78adc 100644
--- a/include/linux/nvmem-consumer.h
+++ b/include/linux/nvmem-consumer.h
@@ -19,6 +19,10 @@ struct device_node;
struct nvmem_cell;
struct nvmem_device;
+/* duplicated from nvmem-provider.h */
+typedef int (*nvmem_cell_post_process_t)(void *priv, const char *id,
int index,
+ unsigned int offset, void *buf, size_t bytes);
+
struct nvmem_cell_info {
const char *name;
unsigned int offset;
@@ -26,6 +30,7 @@ struct nvmem_cell_info {
unsigned int bit_offset;
unsigned int nbits;
struct device_node *np;
+ nvmem_cell_post_process_t post_process;
};
/**
