[PATCH 03/14] gpio: pca953x: Repair multi-byte IO address increment on PCA9575

[Marek Vasut]

The multi-byte IO on various pca953x chips requires the auto-increment bit,
while other chips toggle the LSbit automatically. Note that LSbit toggling
only alternates between two registers during the IO, it is not the same as
address auto-increment. The driver currently assumes that #gpios > 16 implies
auto-increment, while #gpios <= 16 implies LSbit toggling. This is incorrect
at there are chips with 16 GPIOs which require the auto-increment bit.

The PCA9575, according to NXP datasheet rev. 4.2 from 16 April 2015, section
7.3 Command Register, the bit 7 in command register is the auto-increment
bit, which allows programming multiple registers sequentially.

Set this bit both in pca953x_gpio_set_multiple(), where it fixes the multi
register programming, and in pca957x_write_regs_16(), where is simplifies
the function. In fact, the pca957x_write_regs_16() now looks rather similar
to pca953x_write_regs_24() and pca953x_write_regs_16(), which is intended
for subsequent patches.

Signed-off-by: Marek Vasut <marek.vasut+rene...@gmail.com>
Cc: Linus Walleij <linus.wall...@linaro.org>
Cc: Bartosz Golaszewski <bgolaszew...@baylibre.com>
---
 drivers/gpio/gpio-pca953x.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index 4e9c79ca69c5..479fa376bd18 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -215,13 +215,10 @@ static int pca953x_write_regs_16(struct pca953x_chip 
*chip, int reg, u8 *val)
 
 static int pca957x_write_regs_16(struct pca953x_chip *chip, int reg, u8 *val)
 {
-       int ret;
-
-       ret = i2c_smbus_write_byte_data(chip->client, reg << 1, val[0]);
-       if (ret < 0)
-               return ret;
+       u32 regaddr = (reg << 1) | REG_ADDR_AI;
 
-       return i2c_smbus_write_byte_data(chip->client, (reg << 1) + 1, val[1]);
+       return i2c_smbus_write_i2c_block_data(chip->client, regaddr,
+                                             NBANK(chip), val);
 }
 
 static int pca953x_write_regs_24(struct pca953x_chip *chip, int reg, u8 *val)
@@ -408,6 +405,7 @@ static void pca953x_gpio_set_multiple(struct gpio_chip *gc,
 {
        struct pca953x_chip *chip = gpiochip_get_data(gc);
        int bank_shift = pca953x_bank_shift(chip);
+       u32 regaddr = chip->regs->output << bank_shift;
        unsigned int bank_mask, bank_val;
        int bank;
        u8 reg_val[MAX_BANK];
@@ -426,8 +424,13 @@ static void pca953x_gpio_set_multiple(struct gpio_chip *gc,
                }
        }
 
-       ret = i2c_smbus_write_i2c_block_data(chip->client,
-                                            chip->regs->output << bank_shift,
+       /* PCA9575 needs address-increment on multi-byte writes */
+       if ((PCA_CHIP_TYPE(chip->driver_data) == PCA957X_TYPE) &&
+           (NBANK(chip) > 1)) {
+               regaddr |= REG_ADDR_AI;
+       }
+
+       ret = i2c_smbus_write_i2c_block_data(chip->client, regaddr,
                                             NBANK(chip), reg_val);
        if (ret)
                goto exit;
-- 
2.18.0