mfd: rk808: Add register caching

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>

mfd: rk808: Add register caching
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>
Doug Anderson · Lee Jones
1 parent cfeb35da2a
Showing 1 changed file with 30 additions and 0 deletions Side-by-side Diff
drivers/mfd/rk808.c
@@ -29,10 +29,40 @@
 	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[] = {
...	...	@@ -29,10 +29,40 @@
29	29	int value;
30	30	};
31	31
	32	+static bool rk808_is_volatile_reg(struct device *dev, unsigned int reg)
	33	+{
	34	+ /*
	35	+ * Notes:
	36	+ * - Technically the ROUND_30s bit makes RTC_CTRL_REG volatile, but
	37	+ * we don't use that feature. It's better to cache.
	38	+ * - It's unlikely we care that RK808_DEVCTRL_REG is volatile since
	39	+ * bits are cleared in case when we shutoff anyway, but better safe.
	40	+ */
	41	+
	42	+ switch (reg) {
	43	+ case RK808_SECONDS_REG ... RK808_WEEKS_REG:
	44	+ case RK808_RTC_STATUS_REG:
	45	+ case RK808_VB_MON_REG:
	46	+ case RK808_THERMAL_REG:
	47	+ case RK808_DCDC_UV_STS_REG:
	48	+ case RK808_LDO_UV_STS_REG:
	49	+ case RK808_DCDC_PG_REG:
	50	+ case RK808_LDO_PG_REG:
	51	+ case RK808_DEVCTRL_REG:
	52	+ case RK808_INT_STS_REG1:
	53	+ case RK808_INT_STS_REG2:
	54	+ return true;
	55	+ }
	56	+
	57	+ return false;
	58	+}
	59	+
32	60	static const struct regmap_config rk808_regmap_config = {
33	61	.reg_bits = 8,
34	62	.val_bits = 8,
35	63	.max_register = RK808_IO_POL_REG,
	64	+ .cache_type = REGCACHE_RBTREE,
	65	+ .volatile_reg = rk808_is_volatile_reg,
36	66	};
37	67
38	68	static struct resource rtc_resources[] = {