new file mode 100644
@@ -0,0 +1,5 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 CCI kAPI
+^^^^^^^^^^^^^
+.. kernel-doc:: include/media/v4l2-cci.h
@@ -22,6 +22,7 @@ Video4Linux devices
v4l2-mem2mem
v4l2-async
v4l2-fwnode
+ v4l2-cci
v4l2-rect
v4l2-tuner
v4l2-common
@@ -74,6 +74,11 @@ config V4L2_FWNODE
config V4L2_ASYNC
tristate
+config V4L2_CCI
+ tristate
+ depends on I2C
+ select REGMAP_I2C
+
# Used by drivers that need Videobuf modules
config VIDEOBUF_GEN
tristate
@@ -25,6 +25,7 @@ videodev-$(CONFIG_VIDEO_V4L2_I2C) += v4l2-i2c.o
# (e. g. LC_ALL=C sort Makefile)
obj-$(CONFIG_V4L2_ASYNC) += v4l2-async.o
+obj-$(CONFIG_V4L2_CCI) += v4l2-cci.o
obj-$(CONFIG_V4L2_FLASH_LED_CLASS) += v4l2-flash-led-class.o
obj-$(CONFIG_V4L2_FWNODE) += v4l2-fwnode.o
obj-$(CONFIG_V4L2_H264) += v4l2-h264.o
new file mode 100644
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * MIPI Camera Control Interface (CCI) register access helpers.
+ *
+ * Copyright (C) 2023 Hans de Goede <hansg@kernel.org>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/dev_printk.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+#include <asm/unaligned.h>
+
+#include <media/v4l2-cci.h>
+
+int cci_read(struct regmap *map, u32 reg, u64 *val, int *err)
+{
+ int len, ret;
+ u8 buf[8];
+
+ if (err && *err)
+ return *err;
+
+ len = FIELD_GET(CCI_REG_WIDTH_MASK, reg);
+ reg = FIELD_GET(CCI_REG_ADDR_MASK, reg);
+
+ ret = regmap_bulk_read(map, reg, buf, len);
+ if (ret) {
+ dev_err(regmap_get_device(map), "Error reading reg 0x%4x: %d\n", reg, ret);
+ goto out;
+ }
+
+ switch (len) {
+ case 1:
+ *val = buf[0];
+ break;
+ case 2:
+ *val = get_unaligned_be16(buf);
+ break;
+ case 3:
+ *val = get_unaligned_be24(buf);
+ break;
+ case 4:
+ *val = get_unaligned_be32(buf);
+ break;
+ case 8:
+ *val = get_unaligned_be64(buf);
+ break;
+ default:
+ dev_err(regmap_get_device(map), "Error invalid reg-width %d for reg 0x%04x\n",
+ len, reg);
+ ret = -EINVAL;
+ break;
+ }
+
+out:
+ if (ret && err)
+ *err = ret;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(cci_read);
+
+int cci_write(struct regmap *map, u32 reg, u64 val, int *err)
+{
+ int len, ret;
+ u8 buf[8];
+
+ if (err && *err)
+ return *err;
+
+ len = FIELD_GET(CCI_REG_WIDTH_MASK, reg);
+ reg = FIELD_GET(CCI_REG_ADDR_MASK, reg);
+
+ switch (len) {
+ case 1:
+ buf[0] = val;
+ break;
+ case 2:
+ put_unaligned_be16(val, buf);
+ break;
+ case 3:
+ put_unaligned_be24(val, buf);
+ break;
+ case 4:
+ put_unaligned_be32(val, buf);
+ break;
+ case 8:
+ put_unaligned_be64(val, buf);
+ break;
+ default:
+ dev_err(regmap_get_device(map), "Error invalid reg-width %d for reg 0x%04x\n",
+ len, reg);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = regmap_bulk_write(map, reg, buf, len);
+ if (ret)
+ dev_err(regmap_get_device(map), "Error writing reg 0x%4x: %d\n", reg, ret);
+
+out:
+ if (ret && err)
+ *err = ret;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(cci_write);
+
+int cci_update_bits(struct regmap *map, u32 reg, u64 mask, u64 val, int *err)
+{
+ u64 readval;
+ int ret;
+
+ ret = cci_read(map, reg, &readval, err);
+ if (ret)
+ return ret;
+
+ val = (readval & ~mask) | (val & mask);
+
+ return cci_write(map, reg, val, err);
+}
+EXPORT_SYMBOL_GPL(cci_update_bits);
+
+int cci_multi_reg_write(struct regmap *map, const struct cci_reg_sequence *regs,
+ int num_regs, int *err)
+{
+ int i, ret;
+
+ for (i = 0; i < num_regs; i++) {
+ ret = cci_write(map, regs[i].reg, regs[i].val, err);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(cci_multi_reg_write);
+
+struct regmap *cci_regmap_init_i2c(struct i2c_client *client, int reg_addr_bits)
+{
+ struct regmap_config config = {
+ .reg_bits = reg_addr_bits,
+ .val_bits = 8,
+ .reg_format_endian = REGMAP_ENDIAN_BIG,
+ .disable_locking = true,
+ };
+
+ return devm_regmap_init_i2c(client, &config);
+}
+EXPORT_SYMBOL_GPL(cci_regmap_init_i2c);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Hans de Goede <hansg@kernel.org>");
new file mode 100644
@@ -0,0 +1,121 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * MIPI Camera Control Interface (CCI) register access helpers.
+ *
+ * Copyright (C) 2023 Hans de Goede <hansg@kernel.org>
+ */
+#ifndef _V4L2_CCI_H
+#define _V4L2_CCI_H
+
+#include <linux/types.h>
+
+struct i2c_client;
+struct reg_sequence;
+struct regmap;
+
+/**
+ * struct cci_reg_sequence - An individual write from a sequence of CCI writes
+ *
+ * @reg: Register address, use CCI_REG#() macros to encode reg width
+ * @val: Register value
+ *
+ * Register/value pairs for sequences of writes.
+ */
+struct cci_reg_sequence {
+ u32 reg;
+ u64 val;
+};
+
+/*
+ * Macros to define register address with the register width encoded
+ * into the higher bits.
+ */
+#define CCI_REG_ADDR_MASK GENMASK(15, 0)
+#define CCI_REG_WIDTH_SHIFT 16
+#define CCI_REG_WIDTH_MASK GENMASK(19, 16)
+
+#define CCI_REG8(x) ((1 << CCI_REG_WIDTH_SHIFT) | (x))
+#define CCI_REG16(x) ((2 << CCI_REG_WIDTH_SHIFT) | (x))
+#define CCI_REG24(x) ((3 << CCI_REG_WIDTH_SHIFT) | (x))
+#define CCI_REG32(x) ((4 << CCI_REG_WIDTH_SHIFT) | (x))
+#define CCI_REG64(x) ((8 << CCI_REG_WIDTH_SHIFT) | (x))
+
+/**
+ * cci_read() - Read a value from a single CCI register
+ *
+ * @map: Register map to read from
+ * @reg: Register address to read, use CCI_REG#() macros to encode reg width
+ * @val: Pointer to store read value
+ * @err: optional pointer to store errors, if a previous error is set
+ * then the read will be skipped
+ *
+ * Return: %0 on success or a negative error code on failure.
+ */
+int cci_read(struct regmap *map, u32 reg, u64 *val, int *err);
+
+/**
+ * cci_write() - Write a value to a single CCI register
+ *
+ * @map: Register map to write to
+ * @reg: Register address to write, use CCI_REG#() macros to encode reg width
+ * @val: Value to be written
+ * @err: optional pointer to store errors, if a previous error is set
+ * then the write will be skipped
+ *
+ * Return: %0 on success or a negative error code on failure.
+ */
+int cci_write(struct regmap *map, u32 reg, u64 val, int *err);
+
+/**
+ * cci_update_bits() - Perform a read/modify/write cycle on a single CCI register
+ *
+ * @map: Register map to update
+ * @reg: Register address to update, use CCI_REG#() macros to encode reg width
+ * @mask: Bitmask to change
+ * @val: New value for bitmask
+ * @err: optional pointer to store errors, if a previous error is set
+ * then the update will be skipped
+ *
+ * Note this uses read-modify-write to update the bits, atomicity wrt other
+ * cci_*() register access functions is NOT guaranteed.
+ *
+ * Return: %0 on success or a negative error code on failure.
+ */
+int cci_update_bits(struct regmap *map, u32 reg, u64 mask, u64 val, int *err);
+
+/**
+ * cci_multi_reg_write() - Write multiple registers to the device
+ *
+ * @map: Register map to write to
+ * @regs: Array of structures containing register-address, value pairs to be written
+ * register-addresses use CCI_REG#() macros to encode reg width
+ * @num_regs: Number of registers to write
+ * @err: optional pointer to store errors, if a previous error is set
+ * then the write will be skipped
+ *
+ * Write multiple registers to the device where the set of register, value
+ * pairs are supplied in any order, possibly not all in a single range.
+ *
+ * Use of the CCI_REG#() macros to encode reg width is mandatory.
+ *
+ * For raw lists of register-address, -value pairs with only 8 bit
+ * wide writes regmap_multi_reg_write() can be used instead.
+ *
+ * Return: %0 on success or a negative error code on failure.
+ */
+int cci_multi_reg_write(struct regmap *map, const struct cci_reg_sequence *regs,
+ int num_regs, int *err);
+
+/**
+ * cci_regmap_init_i2c() - Create regmap to use with cci_*() register access functions
+ *
+ * @client: i2c_client to create the regmap for
+ * @reg_addr_bits: register address width to use (8 or 16)
+ *
+ * Note the memory for the created regmap is devm() managed, tied to the client.
+ *
+ * Return: %0 on success or a negative error code on failure.
+ */
+struct regmap *cci_regmap_init_i2c(struct i2c_client *client, int reg_addr_bits);
+
+#endif
The CSI2 specification specifies a standard method to access camera sensor registers called "Camera Control Interface (CCI)". This uses either 8 or 16 bit (big-endian wire order) register addresses and supports 8, 16, 24 or 32 bit (big-endian wire order) register widths. Currently a lot of Linux camera sensor drivers all have their own custom helpers for this, often copy and pasted from other drivers. Add a set of generic helpers for this so that all sensor drivers can switch to a single common implementation. These helpers take an extra optional "int *err" function parameter, this can be used to chain a bunch of register accesses together with only a single error check at the end, rather then needing to error check each individual register access. The first failing call will set the contents of err to a non 0 value and all other calls will then become no-ops. Link: https://lore.kernel.org/linux-media/59aefa7f-7bf9-6736-6040-39551329cd0a@redhat.com/ Signed-off-by: Hans de Goede <hdegoede@redhat.com> --- Changes in v2: - Drop cci_reg_type enum - Make having an encoded reg-width mandatory rather then using 0 to encode 8 bit width making reg-addresses without an encoded width default to a width of 8 - Add support for 64 bit wide registers - Introduce a new cci_reg_sequence struct with 64 bit reg values for 64 bit support and without the delay_us field - Various kerneldoc updates - Stop supporting delays in cci_multi_reg_write() - Some includes cleanups - Disable regmap locking --- Documentation/driver-api/media/v4l2-cci.rst | 5 + Documentation/driver-api/media/v4l2-core.rst | 1 + drivers/media/v4l2-core/Kconfig | 5 + drivers/media/v4l2-core/Makefile | 1 + drivers/media/v4l2-core/v4l2-cci.c | 157 +++++++++++++++++++ include/media/v4l2-cci.h | 121 ++++++++++++++ 6 files changed, 290 insertions(+) create mode 100644 Documentation/driver-api/media/v4l2-cci.rst create mode 100644 drivers/media/v4l2-core/v4l2-cci.c create mode 100644 include/media/v4l2-cci.h