[PATCH v4 3/5] clk: qcom: gdsc: Add set and get hwmode callbacks to switch GDSC mode

[Abel Vesa <abel.vesa@linaro.org>]

From: Jagadeesh Kona <quic_jkona@quicinc.com>

Add support for set and get hwmode callbacks to switch the GDSC between
SW and HW modes. Currently, the GDSC is moved to HW control mode
using HW_CTRL flag and if this flag is present, GDSC is moved to HW
mode as part of GDSC enable itself. The intention is to keep the
HW_CTRL flag functionality as is, since many older chipsets still use
this flag.

But consumer drivers also require the GDSC mode to be switched dynamically
at runtime based on requirement for certain usecases. Some of these
usecases are switching the GDSC to SW mode to keep it ON during the
enablement of clocks that are dependent on GDSC and while programming
certain configurations that require GDSC to be ON. Introduce a new
HW_CTRL_TRIGGER flag to register the set_hwmode_dev and get_hwmode_dev
callbacks which allows the consumer drivers to switch the GDSC back and
forth between HW/SW modes dynamically at runtime using new
dev_pm_genpd_set_hwmode API.

Signed-off-by: Jagadeesh Kona <quic_jkona@quicinc.com>
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
---
 drivers/clk/qcom/gdsc.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/clk/qcom/gdsc.h |  1 +
 2 files changed, 55 insertions(+)

diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
index 5358e28122ab..71626eb20101 100644
--- a/drivers/clk/qcom/gdsc.c
+++ b/drivers/clk/qcom/gdsc.c
@@ -363,6 +363,56 @@ static int gdsc_disable(struct generic_pm_domain *domain)
 	return 0;
 }
 
+static int gdsc_set_hwmode(struct generic_pm_domain *domain, struct device *dev, bool mode)
+{
+	struct gdsc *sc = domain_to_gdsc(domain);
+	u32 val;
+	int ret;
+
+	if (sc->rsupply && !regulator_is_enabled(sc->rsupply)) {
+		pr_err("Cannot set mode while parent is disabled\n");
+		return -EIO;
+	}
+
+	ret = gdsc_hwctrl(sc, mode);
+	if (ret)
+		return ret;
+
+	/* Wait for 1usec for mode transition to properly complete */
+	udelay(1);
+
+	if (!mode) {
+		ret = regmap_read(sc->regmap, sc->gdscr, &val);
+		if (ret)
+			return ret;
+
+		/*
+		 * While switching from HW to SW mode, if GDSC is in enabled
+		 * state, poll for GDSC to complete the power up.
+		 */
+		if (!(val & SW_COLLAPSE_MASK))
+			return gdsc_poll_status(sc, GDSC_ON);
+	}
+
+	return 0;
+}
+
+static bool gdsc_get_hwmode(struct generic_pm_domain *domain, struct device *dev)
+{
+	struct gdsc *sc = domain_to_gdsc(domain);
+	u32 val;
+	int ret;
+
+	ret = regmap_read(sc->regmap, sc->gdscr, &val);
+	if (ret)
+		return ret;
+
+	if (val & HW_CONTROL_MASK)
+		return true;
+
+	return false;
+}
+
 static int gdsc_init(struct gdsc *sc)
 {
 	u32 mask, val;
@@ -451,6 +501,10 @@ static int gdsc_init(struct gdsc *sc)
 		sc->pd.power_off = gdsc_disable;
 	if (!sc->pd.power_on)
 		sc->pd.power_on = gdsc_enable;
+	if (sc->flags & HW_CTRL_TRIGGER) {
+		sc->pd.set_hwmode_dev = gdsc_set_hwmode;
+		sc->pd.get_hwmode_dev = gdsc_get_hwmode;
+	}
 
 	ret = pm_genpd_init(&sc->pd, NULL, !on);
 	if (ret)
diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
index 803512688336..1e2779b823d1 100644
--- a/drivers/clk/qcom/gdsc.h
+++ b/drivers/clk/qcom/gdsc.h
@@ -67,6 +67,7 @@ struct gdsc {
 #define ALWAYS_ON	BIT(6)
 #define RETAIN_FF_ENABLE	BIT(7)
 #define NO_RET_PERIPH	BIT(8)
+#define HW_CTRL_TRIGGER	BIT(9)
 	struct reset_controller_dev	*rcdev;
 	unsigned int			*resets;
 	unsigned int			reset_count;

-- 
2.34.1