clk: qcom: gdsc: Add support for gdscs with HW control

Some GDSCs might support a HW control mode, where in the power
domain (gdsc) is brought in and out of low power state (while
unsued) without any SW assistance, saving power.
Such GDSCs can be configured in a HW control mode when powered on
until they are explicitly requested to be powered off by software.
Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/qcom/gdsc.c

@@ -56,6 +56,13 @@ static int gdsc_is_enabled(struct gdsc *sc, unsigned int reg)
 	return !!(val & PWR_ON_MASK);
 }
 
+static int gdsc_hwctrl(struct gdsc *sc, bool en)
+{
+	u32 val = en ? HW_CONTROL_MASK : 0;
+
+	return regmap_update_bits(sc->regmap, sc->gdscr, HW_CONTROL_MASK, val);
+}
+
 static int gdsc_toggle_logic(struct gdsc *sc, bool en)
 {
 	int ret;
@@ -180,6 +187,10 @@ static int gdsc_enable(struct generic_pm_domain *domain)
 	 */
 	udelay(1);
 
+	/* Turn on HW trigger mode if supported */
+	if (sc->flags & HW_CTRL)
+		return gdsc_hwctrl(sc, true);
+
 	return 0;
 }
 
@@ -191,6 +202,13 @@ static int gdsc_disable(struct generic_pm_domain *domain)
 	if (sc->pwrsts == PWRSTS_ON)
 		return gdsc_assert_reset(sc);
 
+	/* Turn off HW trigger mode if supported */
+	if (sc->flags & HW_CTRL) {
+		ret = gdsc_hwctrl(sc, false);
+		if (ret < 0)
+			return ret;
+	}
+
 	if (sc->pwrsts & PWRSTS_OFF)
 		gdsc_clear_mem_on(sc);
 

drivers/clk/qcom/gdsc.h

@@ -52,6 +52,7 @@ struct gdsc {
 	const u8			flags;
 #define VOTABLE		BIT(0)
 #define CLAMP_IO	BIT(1)
+#define HW_CTRL		BIT(2)
 	struct reset_controller_dev	*rcdev;
 	unsigned int			*resets;
 	unsigned int			reset_count;