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Subject[PATCH] gpio-pca953x: fall back to byte-at-a-time for 24-bit io
Date
Using TCA6424A with i2c-piix4 bus driver requires byte-at-a-time IO,
because the i2c-piix4 driver (and probably some SMBus controllers) don't
support I2C_SMBUS_I2C_BLOCK_DATA.

Signed-off-by: Andrew Cooks <andrew.cooks@opengear.com>
---
drivers/gpio/gpio-pca953x.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index 1b9dbf6..9e74934 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -205,11 +205,23 @@ static int pca957x_write_regs_16(struct pca953x_chip *chip, int reg, u8 *val)

static int pca953x_write_regs_24(struct pca953x_chip *chip, int reg, u8 *val)
{
+ int ret, i;
int bank_shift = fls((chip->gpio_chip.ngpio - 1) / BANK_SZ);

- return i2c_smbus_write_i2c_block_data(chip->client,
+ if (i2c_check_functionality(chip->client->adapter,
+ I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
+ return i2c_smbus_write_i2c_block_data(chip->client,
(reg << bank_shift) | REG_ADDR_AI,
NBANK(chip), val);
+ } else {
+ for (i = 0; i < NBANK(chip); i++) {
+ ret = i2c_smbus_write_byte_data(chip->client,
+ (reg << 1) + i, val[i]);
+ if (ret < 0)
+ return ret;
+ }
+ return ret;
+ }
}

static int pca953x_write_regs(struct pca953x_chip *chip, int reg, u8 *val)
@@ -249,7 +261,7 @@ static int pca953x_read_regs_24(struct pca953x_chip *chip, int reg, u8 *val)
{
int bank_shift = fls((chip->gpio_chip.ngpio - 1) / BANK_SZ);

- return i2c_smbus_read_i2c_block_data(chip->client,
+ return i2c_smbus_read_i2c_block_data_or_emulated(chip->client,
(reg << bank_shift) | REG_ADDR_AI,
NBANK(chip), val);
}
--
2.7.4
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