linux-kernel - [PATCH v1 07/14] nvmem: core: add per-cell post processing

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Date:   Thu, 25 Aug 2022 23:44:16 +0200
From:   Michael Walle <michael@...le.cc>
To:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Shawn Guo <shawnguo@...nel.org>, Li Yang <leoyang.li@....com>,
        Rafał Miłecki <rafal@...ecki.pl>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Frank Rowand <frowand.list@...il.com>
Cc:     linux-mtd@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        netdev@...r.kernel.org, Ahmad Fatoum <a.fatoum@...gutronix.de>,
        Michael Walle <michael@...le.cc>
Subject: [PATCH v1 07/14] 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@...le.cc>
---
 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;
 	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;
+
 	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;
 };
 
 /**
-- 
2.30.2