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pwm: pca9685: Make use of register caching in regmap

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This essentially only caches the PRESCALE register because the per channel
registers are affected by the ALL configuration that is used by the virtual
pwm #16. The PRESCALE register is read often so caching it saves quite some
i2c transfers.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/dc25361908ad1dd790f108599bc9dbcc752288a5.1753784092.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
This commit is contained in:
Uwe Kleine-König 2025-07-29 12:36:02 +02:00 committed by Uwe Kleine-König
parent de58556132
commit 3d4c421723
1 changed files with 26 additions and 1 deletions
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27
drivers/pwm/pwm-pca9685.c
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@ -521,11 +521,36 @@ static const struct pwm_ops pca9685_pwm_ops = {
.free = pca9685_pwm_free,
};
static bool pca9685_readable_reg(struct device *dev, unsigned int reg)
{
/* The ALL_LED registers are readable but read as zero */
return reg <= REG_OFF_H(15) || reg >= PCA9685_PRESCALE;
}
static bool pca9685_writeable_reg(struct device *dev, unsigned int reg)
{
return reg <= REG_OFF_H(15) || reg >= PCA9685_ALL_LED_ON_L;
}
static bool pca9685_volatile_reg(struct device *dev, unsigned int reg)
{
/*
* Writing to an ALL_LED register affects all LEDi registers, so they
* are not cachable. :-\
*/
return reg < PCA9685_PRESCALE;
}
static const struct regmap_config pca9685_regmap_i2c_config = {
.reg_bits = 8,
.val_bits = 8,
.readable_reg = pca9685_readable_reg,
.writeable_reg = pca9685_writeable_reg,
.volatile_reg = pca9685_volatile_reg,
.max_register = PCA9685_NUMREGS,
.cache_type = REGCACHE_NONE,
.cache_type = REGCACHE_MAPLE,
};
static int pca9685_pwm_probe(struct i2c_client *client)