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Diffstat (limited to 'target/linux/generic/backport-5.10/803-v5.13-0004-nvmem-core-Add-functions-to-make-number-reading-easy.patch')
| -rw-r--r-- | target/linux/generic/backport-5.10/803-v5.13-0004-nvmem-core-Add-functions-to-make-number-reading-easy.patch | 174 |
1 files changed, 0 insertions, 174 deletions
diff --git a/target/linux/generic/backport-5.10/803-v5.13-0004-nvmem-core-Add-functions-to-make-number-reading-easy.patch b/target/linux/generic/backport-5.10/803-v5.13-0004-nvmem-core-Add-functions-to-make-number-reading-easy.patch deleted file mode 100644 index f791aea8ae..0000000000 --- a/target/linux/generic/backport-5.10/803-v5.13-0004-nvmem-core-Add-functions-to-make-number-reading-easy.patch +++ /dev/null @@ -1,174 +0,0 @@ -From a28e824fb8270eda43fd0f65c2a5fdf33f55c5eb Mon Sep 17 00:00:00 2001 -From: Douglas Anderson <dianders@chromium.org> -Date: Tue, 30 Mar 2021 12:12:37 +0100 -Subject: [PATCH] nvmem: core: Add functions to make number reading easy - -Sometimes the clients of nvmem just want to get a number out of -nvmem. They don't want to think about exactly how many bytes the nvmem -cell took up. They just want the number. Let's make it easy. - -In general this concept is useful because nvmem space is precious and -usually the fewest bits are allocated that will hold a given value on -a given system. However, even though small numbers might be fine on -one system that doesn't mean that logically the number couldn't be -bigger. Imagine nvmem containing a max frequency for a component. On -one system perhaps that fits in 16 bits. On another system it might -fit in 32 bits. The code reading this number doesn't care--it just -wants the number. - -We'll provide two functions: nvmem_cell_read_variable_le_u32() and -nvmem_cell_read_variable_le_u64(). - -Comparing these to the existing functions like nvmem_cell_read_u32(): -* These new functions have no problems if the value was stored in - nvmem in fewer bytes. It's OK to use these function as long as the - value stored will fit in 32-bits (or 64-bits). -* These functions avoid problems that the earlier APIs had with bit - offsets. For instance, you can't use nvmem_cell_read_u32() to read a - value has nbits=32 and bit_offset=4 because the nvmem cell must be - at least 5 bytes big to hold this value. The new API accounts for - this and works fine. -* These functions make it very explicit that they assume that the - number was stored in little endian format. The old functions made - this assumption whenever bit_offset was non-zero (see - nvmem_shift_read_buffer_in_place()) but didn't whenever the - bit_offset was zero. - -NOTE: it's assumed that we don't need an 8-bit or 16-bit version of -this function. The 32-bit version of the function can be used to read -8-bit or 16-bit data. - -At the moment, I'm only adding the "unsigned" versions of these -functions, but if it ends up being useful someone could add a "signed" -version that did 2's complement sign extension. - -At the moment, I'm only adding the "little endian" versions of these -functions. Adding the "big endian" version would require adding "big -endian" support to nvmem_shift_read_buffer_in_place(). - -Signed-off-by: Douglas Anderson <dianders@chromium.org> -Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> -Link: https://lore.kernel.org/r/20210330111241.19401-7-srinivas.kandagatla@linaro.org -Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> ---- - drivers/nvmem/core.c | 95 ++++++++++++++++++++++++++++++++++ - include/linux/nvmem-consumer.h | 4 ++ - 2 files changed, 99 insertions(+) - ---- a/drivers/nvmem/core.c -+++ b/drivers/nvmem/core.c -@@ -1613,6 +1613,101 @@ int nvmem_cell_read_u64(struct device *d - } - EXPORT_SYMBOL_GPL(nvmem_cell_read_u64); - -+static void *nvmem_cell_read_variable_common(struct device *dev, -+ const char *cell_id, -+ size_t max_len, size_t *len) -+{ -+ struct nvmem_cell *cell; -+ int nbits; -+ void *buf; -+ -+ cell = nvmem_cell_get(dev, cell_id); -+ if (IS_ERR(cell)) -+ return cell; -+ -+ nbits = cell->nbits; -+ buf = nvmem_cell_read(cell, len); -+ nvmem_cell_put(cell); -+ if (IS_ERR(buf)) -+ return buf; -+ -+ /* -+ * If nbits is set then nvmem_cell_read() can significantly exaggerate -+ * the length of the real data. Throw away the extra junk. -+ */ -+ if (nbits) -+ *len = DIV_ROUND_UP(nbits, 8); -+ -+ if (*len > max_len) { -+ kfree(buf); -+ return ERR_PTR(-ERANGE); -+ } -+ -+ return buf; -+} -+ -+/** -+ * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number. -+ * -+ * @dev: Device that requests the nvmem cell. -+ * @cell_id: Name of nvmem cell to read. -+ * @val: pointer to output value. -+ * -+ * Return: 0 on success or negative errno. -+ */ -+int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id, -+ u32 *val) -+{ -+ size_t len; -+ u8 *buf; -+ int i; -+ -+ buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len); -+ if (IS_ERR(buf)) -+ return PTR_ERR(buf); -+ -+ /* Copy w/ implicit endian conversion */ -+ *val = 0; -+ for (i = 0; i < len; i++) -+ *val |= buf[i] << (8 * i); -+ -+ kfree(buf); -+ -+ return 0; -+} -+EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32); -+ -+/** -+ * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number. -+ * -+ * @dev: Device that requests the nvmem cell. -+ * @cell_id: Name of nvmem cell to read. -+ * @val: pointer to output value. -+ * -+ * Return: 0 on success or negative errno. -+ */ -+int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id, -+ u64 *val) -+{ -+ size_t len; -+ u8 *buf; -+ int i; -+ -+ buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len); -+ if (IS_ERR(buf)) -+ return PTR_ERR(buf); -+ -+ /* Copy w/ implicit endian conversion */ -+ *val = 0; -+ for (i = 0; i < len; i++) -+ *val |= buf[i] << (8 * i); -+ -+ kfree(buf); -+ -+ return 0; -+} -+EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64); -+ - /** - * nvmem_device_cell_read() - Read a given nvmem device and cell - * ---- a/include/linux/nvmem-consumer.h -+++ b/include/linux/nvmem-consumer.h -@@ -65,6 +65,10 @@ int nvmem_cell_read_u8(struct device *de - int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val); - int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val); - int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val); -+int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id, -+ u32 *val); -+int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id, -+ u64 *val); - - /* direct nvmem device read/write interface */ - struct nvmem_device *nvmem_device_get(struct device *dev, const char *name); |