Some gdscs can support an intermediate RETENTION state apart from
the ON and OFF states. The RETENTION state can further be configured
to either retain all memory, or just some part of it (periperal or
core).
This patch adds support so gdscs can support the additional RET state
which the client drivers can then choose based on acceptable
latency.

Signed-off-by: Rajendra Nayak <rna...@codeaurora.org>
---
 drivers/clk/qcom/gdsc.c | 81 ++++++++++++++++++++++++++++++++++++++++++-------
 drivers/clk/qcom/gdsc.h | 22 +++++++++-----
 2 files changed, 85 insertions(+), 18 deletions(-)

diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
index f12d7b2..e0859df 100644
--- a/drivers/clk/qcom/gdsc.c
+++ b/drivers/clk/qcom/gdsc.c
@@ -38,6 +38,7 @@
 
 #define RETAIN_MEM             BIT(14)
 #define RETAIN_PERIPH          BIT(13)
+#define OFF_PERIPH             BIT(12)
 
 #define TIMEOUT_US             100
 
@@ -122,24 +123,56 @@ static inline int gdsc_assert_reset(struct gdsc *sc)
        return 0;
 }
 
-static inline void gdsc_force_mem_on(struct gdsc *sc)
+static inline void gdsc_force_mem_core_on(struct gdsc *sc)
 {
        int i;
-       u32 mask = RETAIN_MEM | RETAIN_PERIPH;
+       u32 mask = RETAIN_MEM;
 
        for (i = 0; i < sc->cxc_count; i++)
                regmap_update_bits(sc->regmap, sc->cxcs[i], mask, mask);
 }
 
-static inline void gdsc_clear_mem_on(struct gdsc *sc)
+static inline void gdsc_force_mem_periph_on(struct gdsc *sc)
 {
        int i;
-       u32 mask = RETAIN_MEM | RETAIN_PERIPH;
+       u32 mask = RETAIN_PERIPH | OFF_PERIPH;
+       u32 val = RETAIN_PERIPH;
+
+       for (i = 0; i < sc->cxc_count; i++)
+               regmap_update_bits(sc->regmap, sc->cxcs[i], mask, val);
+}
+
+static inline void gdsc_force_mem_on(struct gdsc *sc)
+{
+       gdsc_force_mem_core_on(sc);
+       gdsc_force_mem_periph_on(sc);
+}
+
+static inline void gdsc_clear_mem_core_on(struct gdsc *sc)
+{
+       int i;
+       u32 mask = RETAIN_MEM;
 
        for (i = 0; i < sc->cxc_count; i++)
                regmap_update_bits(sc->regmap, sc->cxcs[i], mask, 0);
 }
 
+static inline void gdsc_clear_mem_periph_on(struct gdsc *sc)
+{
+       int i;
+       u32 mask = RETAIN_PERIPH | OFF_PERIPH;
+       u32 val = OFF_PERIPH;
+
+       for (i = 0; i < sc->cxc_count; i++)
+               regmap_update_bits(sc->regmap, sc->cxcs[i], mask, val);
+}
+
+static inline void gdsc_clear_mem_on(struct gdsc *sc)
+{
+       gdsc_clear_mem_core_on(sc);
+       gdsc_clear_mem_periph_on(sc);
+}
+
 static int gdsc_enable(struct generic_pm_domain *domain)
 {
        struct gdsc *sc = domain_to_gdsc(domain);
@@ -152,8 +185,7 @@ static int gdsc_enable(struct generic_pm_domain *domain)
        if (ret)
                return ret;
 
-       if (sc->pwrsts & PWRSTS_OFF)
-               gdsc_force_mem_on(sc);
+       gdsc_force_mem_on(sc);
 
        /*
         * If clocks to this power domain were already on, they will take an
@@ -170,12 +202,35 @@ static int gdsc_enable(struct generic_pm_domain *domain)
 static int gdsc_disable(struct generic_pm_domain *domain)
 {
        struct gdsc *sc = domain_to_gdsc(domain);
+       u8 pwrst;
 
        if (sc->pwrsts == PWRSTS_ON)
                return gdsc_assert_reset(sc);
 
-       if (sc->pwrsts & PWRSTS_OFF)
+       if (domain->state_count > 1)
+               pwrst = 1 << domain->state_idx;
+       else if (sc->pwrsts & PWRSTS_OFF)
+               pwrst = PWRSTS_OFF;
+       else
+               pwrst = PWRSTS_RET;
+
+       switch (pwrst) {
+       case PWRSTS_OFF:
                gdsc_clear_mem_on(sc);
+               break;
+       case PWRSTS_RET:
+               if (sc->pwrsts_ret == PWRSTS_RET_ALL)
+                       gdsc_force_mem_on(sc);
+               else if (sc->pwrsts_ret == PWRSTS_RET_MEM)
+                       gdsc_force_mem_core_on(sc);
+               else if (sc->pwrsts_ret == PWRSTS_RET_PERIPH)
+                       gdsc_force_mem_periph_on(sc);
+               else
+                       return -EINVAL;
+               break;
+       default:
+               return -EINVAL;
+       };
 
        return gdsc_toggle_logic(sc, false);
 }
@@ -198,6 +253,9 @@ static int gdsc_init(struct gdsc *sc)
        if (ret)
                return ret;
 
+       if (!sc->pwrsts)
+               return -EINVAL;
+
        /* Force gdsc ON if only ON state is supported */
        if (sc->pwrsts == PWRSTS_ON) {
                ret = gdsc_toggle_logic(sc, true);
@@ -217,14 +275,15 @@ static int gdsc_init(struct gdsc *sc)
        if ((sc->flags & VOTABLE) && on)
                gdsc_enable(&sc->pd);
 
-       if (on || (sc->pwrsts & PWRSTS_RET))
+       if (on)
                gdsc_force_mem_on(sc);
-       else
-               gdsc_clear_mem_on(sc);
 
        sc->pd.power_off = gdsc_disable;
        sc->pd.power_on = gdsc_enable;
-       pm_genpd_init(&sc->pd, NULL, !on);
+       if (sc->pd.state_count)
+               pm_genpd_init(&sc->pd, &simple_qos_governor, !on);
+       else
+               pm_genpd_init(&sc->pd, NULL, !on);
 
        return 0;
 }
diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
index 3bf497c..0032c96 100644
--- a/drivers/clk/qcom/gdsc.h
+++ b/drivers/clk/qcom/gdsc.h
@@ -41,15 +41,23 @@ struct gdsc {
        unsigned int                    gds_hw_ctrl;
        unsigned int                    *cxcs;
        unsigned int                    cxc_count;
+/* supported options for pwrsts */
+#define PWRSTS_RET                     BIT(0)
+#define PWRSTS_OFF                     BIT(1)
+#define PWRSTS_ON                      BIT(2)
+#define PWRSTS_MAX                     3
+#define PWRSTS_OFF_ON                  (PWRSTS_OFF | PWRSTS_ON)
+#define PWRSTS_RET_ON                  (PWRSTS_RET | PWRSTS_ON)
+#define PWRSTS_OFF_RET_ON              (PWRSTS_OFF | PWRSTS_RET | PWRSTS_ON)
        const u8                        pwrsts;
-/* Powerdomain allowable state bitfields */
-#define PWRSTS_OFF             BIT(0)
-#define PWRSTS_RET             BIT(1)
-#define PWRSTS_ON              BIT(2)
-#define PWRSTS_OFF_ON          (PWRSTS_OFF | PWRSTS_ON)
-#define PWRSTS_RET_ON          (PWRSTS_RET | PWRSTS_ON)
+/* supported options for pwrsts_ret */
+#define PWRSTS_RET_ALL                 0 /* default retains all */
+#define PWRSTS_RET_MEM                 BIT(0)
+#define PWRSTS_RET_PERIPH              BIT(1)
+       const u8                        pwrsts_ret;
+/* supported flags */
+#define VOTABLE                                BIT(0)
        const u8                        flags;
-#define VOTABLE                BIT(0)
        struct reset_controller_dev     *rcdev;
        unsigned int                    *resets;
        unsigned int                    reset_count;
-- 
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