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mfd: rk808: Add register caching

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Let's define the voltatile registers (those that can't be cached) and
enable caching.  The rk808 is accessed almost constantly with cpufreq
so this is really nice.

As measured by ftrace:
  before this change: cpu0_set_target() => ~2200us
  after this change:  cpu0_set_target() =>  ~500us

Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Chris Zhong <zyw@rock-chips.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
Doug Anderson 2014-09-09 16:06:04 -07:00 committed by Lee Jones
parent cfeb35da2a
commit 2adb3b8e6f
1 changed files with 30 additions and 0 deletions
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30
drivers/mfd/rk808.c
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@ -29,10 +29,40 @@ struct rk808_reg_data {
int value;
};
static bool rk808_is_volatile_reg(struct device *dev, unsigned int reg)
{
/*
* Notes:
* - Technically the ROUND_30s bit makes RTC_CTRL_REG volatile, but
* we don't use that feature. It's better to cache.
* - It's unlikely we care that RK808_DEVCTRL_REG is volatile since
* bits are cleared in case when we shutoff anyway, but better safe.
*/
switch (reg) {
case RK808_SECONDS_REG ... RK808_WEEKS_REG:
case RK808_RTC_STATUS_REG:
case RK808_VB_MON_REG:
case RK808_THERMAL_REG:
case RK808_DCDC_UV_STS_REG:
case RK808_LDO_UV_STS_REG:
case RK808_DCDC_PG_REG:
case RK808_LDO_PG_REG:
case RK808_DEVCTRL_REG:
case RK808_INT_STS_REG1:
case RK808_INT_STS_REG2:
return true;
}
return false;
}
static const struct regmap_config rk808_regmap_config = {
.reg_bits = 8,
.val_bits = 8,
.max_register = RK808_IO_POL_REG,
.cache_type = REGCACHE_RBTREE,
.volatile_reg = rk808_is_volatile_reg,
};
static struct resource rtc_resources[] = {