From 55d4980ce55b6bb4be66877de4dbec513911b988 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= Date: Tue, 4 Apr 2023 18:21:42 +0100 Subject: [PATCH] nvmem: core: support specifying both: cell raw data & post read lengths MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Callback .read_post_process() is designed to modify raw cell content before providing it to the consumer. So far we were dealing with modifications that didn't affect cell size (length). In some cases however cell content needs to be reformatted and resized. It's required e.g. to provide properly formatted MAC address in case it's stored in a non-binary format (e.g. using ASCII). There were few discussions how to optimally handle that. Following possible solutions were considered: 1. Allow .read_post_process() to realloc (resize) content buffer 2. Allow .read_post_process() to adjust (decrease) just buffer length 3. Register NVMEM cells using post-read sizes The preferred solution was the last one. The problem is that simply adjusting "bytes" in NVMEM providers would result in core code NOT passing whole raw data to .read_post_process() callbacks. It means callback functions couldn't do their job without somehow manually reading original cell content on their own. This patch deals with that by registering NVMEM cells with both lengths: raw content one and post read one. It allows: 1. Core code to read whole raw cell content 2. Callbacks to return content they want Signed-off-by: Rafał Miłecki Signed-off-by: Srinivas Kandagatla Link: https://lore.kernel.org/r/20230404172148.82422-35-srinivas.kandagatla@linaro.org Signed-off-by: Greg Kroah-Hartman --- drivers/nvmem/core.c | 11 +++++++---- include/linux/nvmem-provider.h | 2 ++ 2 files changed, 9 insertions(+), 4 deletions(-) --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -50,6 +50,7 @@ struct nvmem_device { struct nvmem_cell_entry { const char *name; int offset; + size_t raw_len; int bytes; int bit_offset; int nbits; @@ -469,6 +470,7 @@ static int nvmem_cell_info_to_nvmem_cell { cell->nvmem = nvmem; cell->offset = info->offset; + cell->raw_len = info->raw_len ?: info->bytes; cell->bytes = info->bytes; cell->name = info->name; cell->read_post_process = info->read_post_process; @@ -1560,7 +1562,7 @@ static int __nvmem_cell_read(struct nvme { int rc; - rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes); + rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->raw_len); if (rc) return rc; @@ -1571,7 +1573,7 @@ static int __nvmem_cell_read(struct nvme if (cell->read_post_process) { rc = cell->read_post_process(cell->priv, id, index, - cell->offset, buf, cell->bytes); + cell->offset, buf, cell->raw_len); if (rc) return rc; } @@ -1594,14 +1596,15 @@ static int __nvmem_cell_read(struct nvme */ void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len) { - struct nvmem_device *nvmem = cell->entry->nvmem; + struct nvmem_cell_entry *entry = cell->entry; + struct nvmem_device *nvmem = entry->nvmem; u8 *buf; int rc; if (!nvmem) return ERR_PTR(-EINVAL); - buf = kzalloc(cell->entry->bytes, GFP_KERNEL); + buf = kzalloc(max_t(size_t, entry->raw_len, entry->bytes), GFP_KERNEL); if (!buf) return ERR_PTR(-ENOMEM); --- a/include/linux/nvmem-provider.h +++ b/include/linux/nvmem-provider.h @@ -51,6 +51,7 @@ struct nvmem_keepout { * struct nvmem_cell_info - NVMEM cell description * @name: Name. * @offset: Offset within the NVMEM device. + * @raw_len: Length of raw data (without post processing). * @bytes: Length of the cell. * @bit_offset: Bit offset if cell is smaller than a byte. * @nbits: Number of bits. @@ -62,6 +63,7 @@ struct nvmem_keepout { struct nvmem_cell_info { const char *name; unsigned int offset; + size_t raw_len; unsigned int bytes; unsigned int bit_offset; unsigned int nbits;