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regmap-i2c: add 16-bit width registers support 

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@canonical.com>
Link: https://lore.kernel.org/r/20200424123358.144850-1-acelan.kao@canonical.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
AceLan Kao 2020-04-24 20:33:58 +08:00 committed by Mark Brown
parent 148c01d176
commit 82f25bd73c
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GPG Key ID: 24D68B725D5487D0
1 changed files with 61 additions and 0 deletions
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61
drivers/base/regmap/regmap-i2c.c
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@ -246,6 +246,63 @@ static const 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)
{
@ -255,6 +312,10 @@ static const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
i2c_check_functionality(i2c->adapter,
I2C_FUNC_SMBUS_I2C_BLOCK))
return &regmap_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 &regmap_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))