This is a note to let you know that I've just added the patch titled
regmap-i2c: add 16-bit width registers support
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
regmap-i2c-add-16-bit-width-registers-support.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ee5d7277ae0fd7cda3208f95b7cfa51484e5a930
Author: AceLan Kao <acelan.kao@xxxxxxxxxxxxx>
Date: Fri Apr 24 20:33:58 2020 +0800
regmap-i2c: add 16-bit width registers support
[ Upstream commit 82f25bd73c0bee4d29df47007a4f7290695b7db7 ]
This allows to access data with 16-bit width of registers
via i2c SMBus block functions.
The multi-command sequence of the reading function is not safe
and may read the wrong data from other address if other commands
are sent in-between the SMBus commands in the read function.
Read performance:
32768 bytes (33 kB, 32 KiB) copied, 11.4869 s, 2.9 kB/s
Write performance(with 1-byte page):
32768 bytes (33 kB, 32 KiB) copied, 129.591 s, 0.3 kB/s
The implementation is inspired by below commit
https://patchwork.ozlabs.org/patch/545292/
v2: add more descriptions about the issue that maybe introduced
by this commit
Signed-off-by: AceLan Kao <acelan.kao@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20200424123358.144850-1-acelan.kao@xxxxxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Stable-dep-of: 0c9d2eb5e947 ("regmap: Account for register length in SMBus I/O limits")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index 056acde5e7d34..052170ca0255e 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -250,6 +250,63 @@ static struct regmap_bus regmap_i2c_smbus_i2c_block = {
.max_raw_write = I2C_SMBUS_BLOCK_MAX,
};
+static int regmap_i2c_smbus_i2c_write_reg16(void *context, const void *data,
+ size_t count)
+{
+ struct device *dev = context;
+ struct i2c_client *i2c = to_i2c_client(dev);
+
+ if (count < 2)
+ return -EINVAL;
+
+ count--;
+ return i2c_smbus_write_i2c_block_data(i2c, ((u8 *)data)[0], count,
+ (u8 *)data + 1);
+}
+
+static int regmap_i2c_smbus_i2c_read_reg16(void *context, const void *reg,
+ size_t reg_size, void *val,
+ size_t val_size)
+{
+ struct device *dev = context;
+ struct i2c_client *i2c = to_i2c_client(dev);
+ int ret, count, len = val_size;
+
+ if (reg_size != 2)
+ return -EINVAL;
+
+ ret = i2c_smbus_write_byte_data(i2c, ((u16 *)reg)[0] & 0xff,
+ ((u16 *)reg)[0] >> 8);
+ if (ret < 0)
+ return ret;
+
+ count = 0;
+ do {
+ /* Current Address Read */
+ ret = i2c_smbus_read_byte(i2c);
+ if (ret < 0)
+ break;
+
+ *((u8 *)val++) = ret;
+ count++;
+ len--;
+ } while (len > 0);
+
+ if (count == val_size)
+ return 0;
+ else if (ret < 0)
+ return ret;
+ else
+ return -EIO;
+}
+
+static const struct regmap_bus regmap_i2c_smbus_i2c_block_reg16 = {
+ .write = regmap_i2c_smbus_i2c_write_reg16,
+ .read = regmap_i2c_smbus_i2c_read_reg16,
+ .max_raw_read = I2C_SMBUS_BLOCK_MAX,
+ .max_raw_write = I2C_SMBUS_BLOCK_MAX,
+};
+
static const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
const struct regmap_config *config)
{
@@ -259,6 +316,10 @@ static const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
i2c_check_functionality(i2c->adapter,
I2C_FUNC_SMBUS_I2C_BLOCK))
return ®map_i2c_smbus_i2c_block;
+ else if (config->val_bits == 8 && config->reg_bits == 16 &&
+ i2c_check_functionality(i2c->adapter,
+ I2C_FUNC_SMBUS_I2C_BLOCK))
+ return ®map_i2c_smbus_i2c_block_reg16;
else if (config->val_bits == 16 && config->reg_bits == 8 &&
i2c_check_functionality(i2c->adapter,
I2C_FUNC_SMBUS_WORD_DATA))
