[v2,5/5] gpio: pca953x: refactor pca953x_read_regs()

Avoid the unnecessary if-else in pca953x_read_regs() by spltting the
routine into smaller, specialized functions and calling the right one
via a function pointer held in struct pca953x.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/gpio/gpio-pca953x.c | 55 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 39 insertions(+), 16 deletions(-)

On Wed, 2016-09-07 at 11:24 +0200, Bartosz Golaszewski wrote:
> Avoid the unnecessary if-else in pca953x_read_regs() by spltting the
> routine into smaller, specialized functions and calling the right one
> via a function pointer held in struct pca953x.
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
>  drivers/gpio/gpio-pca953x.c | 55 ++++++++++++++++++++++++++++++++--
> -----------
>  1 file changed, 39 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
> index 00bb2ea..e417c42 100644
> --- a/drivers/gpio/gpio-pca953x.c
> +++ b/drivers/gpio/gpio-pca953x.c
> @@ -134,6 +134,7 @@ struct pca953x_chip {
>  	const struct pca953x_offset *offset;
>  
>  	int (*write_regs)(struct pca953x_chip *, int, u8 *);
> +	int (*read_regs)(struct pca953x_chip *, int, u8 *);
>  };
>  
>  static int pca953x_read_single(struct pca953x_chip *chip, int reg,
> u32 *val,
> @@ -219,24 +220,41 @@ static int pca953x_write_regs(struct
> pca953x_chip *chip, int reg, u8 *val)
>  	return 0;
>  }
>  
> -static int pca953x_read_regs(struct pca953x_chip *chip, int reg, u8
> *val)
> +static int pca953x_read_regs_8(struct pca953x_chip *chip, int reg, u8
> *val)
>  {
>  	int ret;
>  
> -	if (chip->gpio_chip.ngpio <= 8) {
> -		ret = i2c_smbus_read_byte_data(chip->client, reg);
> -		*val = ret;
> -	} else if (chip->gpio_chip.ngpio >= 24) {
> -		int bank_shift = fls((chip->gpio_chip.ngpio - 1) /
> BANK_SZ);
> +	ret = i2c_smbus_read_byte_data(chip->client, reg);
> +	*val = ret;
>  
> -		ret = i2c_smbus_read_i2c_block_data(chip->client,
> -					(reg << bank_shift) |
> REG_ADDR_AI,
> -					NBANK(chip), val);
> -	} else {
> -		ret = i2c_smbus_read_word_data(chip->client, reg <<
> 1);
> -		val[0] = (u16)ret & 0xFF;
> -		val[1] = (u16)ret >> 8;
> -	}
> +	return ret;
> +}
> +
> +static int pca953x_read_regs_16(struct pca953x_chip *chip, int reg,
> u8 *val)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_read_word_data(chip->client, reg << 1);
> +	val[0] = (u16)ret & 0xFF;
> +	val[1] = (u16)ret >> 8;
> +
> +	return ret;
> +}
> +
> +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,
> +					     (reg << bank_shift) |
> REG_ADDR_AI,
> +					     NBANK(chip), val);
> +}
> +
> +static int pca953x_read_regs(struct pca953x_chip *chip, int reg, u8
> *val)
> +{
> +	int ret;
> +
> +	ret = chip->read_regs(chip, reg, val);
>  	if (ret < 0) {
>  		dev_err(&chip->client->dev, "failed reading
> register\n");
>  		return ret;
> @@ -766,10 +784,15 @@ static int pca953x_probe(struct i2c_client
> *client,
>  	 */
>  	pca953x_setup_gpio(chip, chip->driver_data & PCA_GPIO_MASK);
>  
> -	if (chip->gpio_chip.ngpio <= 8)
> +	if (chip->gpio_chip.ngpio <= 8) {
>  		chip->write_regs = pca953x_write_regs_8;
> -	else if (chip->gpio_chip.ngpio >= 24)
> +		chip->read_regs = pca953x_read_regs_8;
> +	} else if (chip->gpio_chip.ngpio >= 24) {
>  		chip->write_regs = pca953x_write_regs_24;
> +		chip->read_regs = pca953x_read_regs_24;
> +	} else {
> +		chip->read_regs = pca953x_read_regs_16;
> +	}

For sake of consolidation stuff can we move write_regs_16 variants here?
It might require to refactor patch 3 as well


>  
>  	if (PCA_CHIP_TYPE(chip->driver_data) == PCA953X_TYPE)
>  		ret = device_pca953x_init(chip, invert);