clk: qcom: gdsc: Add support to enable retention of GSDCR

Add support for the RETAIN_FF_ENABLE feature which enables the
usage of retention registers. These registers maintain their
state after disabling and re-enabling a GDSC.
Signed-off-by: Taniya Das <tdas@codeaurora.org>
Link: https://lore.kernel.org/r/1595606878-2664-2-git-send-email-tdas@codeaurora.orgSigned-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/qcom/gdsc.c

@@ -30,6 +30,7 @@
 /* CFG_GDSCR */
 #define GDSC_POWER_UP_COMPLETE		BIT(16)
 #define GDSC_POWER_DOWN_COMPLETE	BIT(15)
+#define GDSC_RETAIN_FF_ENABLE		BIT(11)
 #define CFG_GDSCR_OFFSET		0x4
 
 /* Wait 2^n CXO cycles between all states. Here, n=2 (4 cycles). */
@@ -217,6 +218,14 @@ static inline void gdsc_assert_reset_aon(struct gdsc *sc)
 	regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
 			   GMEM_RESET_MASK, 0);
 }
+
+static void gdsc_retain_ff_on(struct gdsc *sc)
+{
+	u32 mask = GDSC_RETAIN_FF_ENABLE;
+
+	regmap_update_bits(sc->regmap, sc->gdscr, mask, mask);
+}
+
 static int gdsc_enable(struct generic_pm_domain *domain)
 {
 	struct gdsc *sc = domain_to_gdsc(domain);
@@ -269,6 +278,9 @@ static int gdsc_enable(struct generic_pm_domain *domain)
 		udelay(1);
 	}
 
+	if (sc->flags & RETAIN_FF_ENABLE)
+		gdsc_retain_ff_on(sc);
+
 	return 0;
 }
 

drivers/clk/qcom/gdsc.h

@@ -50,6 +50,7 @@ struct gdsc {
 #define AON_RESET	BIT(4)
 #define POLL_CFG_GDSCR	BIT(5)
 #define ALWAYS_ON	BIT(6)
+#define RETAIN_FF_ENABLE	BIT(7)
 	struct reset_controller_dev	*rcdev;
 	unsigned int			*resets;
 	unsigned int			reset_count;