clk: qcom: gdsc: Add support for ON only state

Certain devices can have GDSCs' which support ON as the only state.
They can't be power collapsed to either hit RET or OFF.
The clients drivers for these GDSCs' however would expect the state
of the core to be reset following a GDSC disable and re-enable.
To do this assert/deassert reset lines every time the client
driver would request the GDSC to be powered on/off instead.

Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/qcom/common.c

@@ -125,7 +125,8 @@ int qcom_cc_really_probe(struct platform_device *pdev,
 		goto err_reset;
 
 	if (desc->gdscs && desc->num_gdscs) {
-		ret = gdsc_register(dev, desc->gdscs, desc->num_gdscs, regmap);
+		ret = gdsc_register(dev, desc->gdscs, desc->num_gdscs,
+				    &reset->rcdev, regmap);
 		if (ret)
 			goto err_pd;
 	}

drivers/clk/qcom/gdsc.c

@@ -18,6 +18,7 @@
 #include <linux/kernel.h>
 #include <linux/pm_domain.h>
 #include <linux/regmap.h>
+#include <linux/reset-controller.h>
 #include <linux/slab.h>
 #include "gdsc.h"
 
@@ -84,6 +85,24 @@ static int gdsc_toggle_logic(struct gdsc *sc, bool en)
 	return -ETIMEDOUT;
 }
 
+static inline int gdsc_deassert_reset(struct gdsc *sc)
+{
+	int i;
+
+	for (i = 0; i < sc->reset_count; i++)
+		sc->rcdev->ops->deassert(sc->rcdev, sc->resets[i]);
+	return 0;
+}
+
+static inline int gdsc_assert_reset(struct gdsc *sc)
+{
+	int i;
+
+	for (i = 0; i < sc->reset_count; i++)
+		sc->rcdev->ops->assert(sc->rcdev, sc->resets[i]);
+	return 0;
+}
+
 static inline void gdsc_force_mem_on(struct gdsc *sc)
 {
 	int i;
@@ -107,6 +126,9 @@ static int gdsc_enable(struct generic_pm_domain *domain)
 	struct gdsc *sc = domain_to_gdsc(domain);
 	int ret;
 
+	if (sc->pwrsts == PWRSTS_ON)
+		return gdsc_deassert_reset(sc);
+
 	ret = gdsc_toggle_logic(sc, true);
 	if (ret)
 		return ret;
@@ -130,6 +152,9 @@ static int gdsc_disable(struct generic_pm_domain *domain)
 {
 	struct gdsc *sc = domain_to_gdsc(domain);
 
+	if (sc->pwrsts == PWRSTS_ON)
+		return gdsc_assert_reset(sc);
+
 	if (sc->pwrsts & PWRSTS_OFF)
 		gdsc_clear_mem_on(sc);
 
@@ -153,6 +178,13 @@ static int gdsc_init(struct gdsc *sc)
 	if (ret)
 		return ret;
 
+	/* Force gdsc ON if only ON state is supported */
+	if (sc->pwrsts == PWRSTS_ON) {
+		ret = gdsc_toggle_logic(sc, true);
+		if (ret)
+			return ret;
+	}
+
 	on = gdsc_is_enabled(sc);
 	if (on < 0)
 		return on;
@@ -170,7 +202,7 @@ static int gdsc_init(struct gdsc *sc)
 }
 
 int gdsc_register(struct device *dev, struct gdsc **scs, size_t num,
-		  struct regmap *regmap)
+		  struct reset_controller_dev *rcdev, struct regmap *regmap)
 {
 	int i, ret;
 	struct genpd_onecell_data *data;
@@ -189,6 +221,7 @@ int gdsc_register(struct device *dev, struct gdsc **scs, size_t num,
 		if (!scs[i])
 			continue;
 		scs[i]->regmap = regmap;
+		scs[i]->rcdev = rcdev;
 		ret = gdsc_init(scs[i]);
 		if (ret)
 			return ret;

drivers/clk/qcom/gdsc.h

@@ -18,6 +18,7 @@
 #include <linux/pm_domain.h>
 
 struct regmap;
+struct reset_controller_dev;
 
 /* Powerdomain allowable state bitfields */
 #define PWRSTS_OFF		BIT(0)
@@ -34,6 +35,9 @@ struct regmap;
  * @cxcs: offsets of branch registers to toggle mem/periph bits in
  * @cxc_count: number of @cxcs
  * @pwrsts: Possible powerdomain power states
+ * @resets: ids of resets associated with this gdsc
+ * @reset_count: number of @resets
+ * @rcdev: reset controller
  */
 struct gdsc {
 	struct generic_pm_domain	pd;
@@ -42,13 +46,18 @@ struct gdsc {
 	unsigned int			*cxcs;
 	unsigned int			cxc_count;
 	const u8			pwrsts;
+	struct reset_controller_dev	*rcdev;
+	unsigned int			*resets;
+	unsigned int			reset_count;
 };
 
 #ifdef CONFIG_QCOM_GDSC
-int gdsc_register(struct device *, struct gdsc **, size_t n, struct regmap *);
+int gdsc_register(struct device *, struct gdsc **, size_t n,
+		  struct reset_controller_dev *, struct regmap *);
 void gdsc_unregister(struct device *);
 #else
 static inline int gdsc_register(struct device *d, struct gdsc **g, size_t n,
+				struct reset_controller_dev *rcdev,
 				struct regmap *r)
 {
 	return -ENOSYS;