clk: qcom: gdsc: Add support to update GDSC transition delay

GDSCs have multiple transition delays which are used for the GDSC FSM
states. Older targets/designs required these values to be updated from
gdsc code to certain default values for the FSM state to work as
expected. But on the newer targets/designs the values updated from the
GDSC driver can hamper the FSM state to not work as expected.

On SC7180 we observe black screens because the gdsc is being
enabled/disabled very rapidly and the GDSC FSM state does not work as
expected. This is due to the fact that the GDSC reset value is being
updated from SW.

Thus add support to update the transition delay from the clock
controller gdscs as required.

Fixes: 45dd0e5 ("clk: qcom: Add support for GDSCs)
Signed-off-by: Taniya Das <tdas@codeaurora.org>
Link: https://lore.kernel.org/r/20220223185606.3941-1-tdas@codeaurora.org
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/qcom/gdsc.c

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (c) 2015, 2017-2018, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2015, 2017-2018, 2022, The Linux Foundation. All rights reserved.
  */
 
 #include <linux/bitops.h>
@@ -35,9 +35,14 @@
 #define CFG_GDSCR_OFFSET 0x4
 
 /* Wait 2^n CXO cycles between all states. Here, n=2 (4 cycles). */
-#define EN_REST_WAIT_VAL (0x2 << 20)
-#define EN_FEW_WAIT_VAL (0x8 << 16)
-#define CLK_DIS_WAIT_VAL (0x2 << 12)
+#define EN_REST_WAIT_VAL 0x2
+#define EN_FEW_WAIT_VAL 0x8
+#define CLK_DIS_WAIT_VAL 0x2
+
+/* Transition delay shifts */
+#define EN_REST_WAIT_SHIFT 20
+#define EN_FEW_WAIT_SHIFT 16
+#define CLK_DIS_WAIT_SHIFT 12
 
 #define RETAIN_MEM BIT(14)
 #define RETAIN_PERIPH BIT(13)
@@ -380,7 +385,18 @@ static int gdsc_init(struct gdsc *sc)
  */
  mask = HW_CONTROL_MASK | SW_OVERRIDE_MASK |
  EN_REST_WAIT_MASK | EN_FEW_WAIT_MASK | CLK_DIS_WAIT_MASK;
- val = EN_REST_WAIT_VAL | EN_FEW_WAIT_VAL | CLK_DIS_WAIT_VAL;
+
+ if (!sc->en_rest_wait_val)
+ sc->en_rest_wait_val = EN_REST_WAIT_VAL;
+ if (!sc->en_few_wait_val)
+ sc->en_few_wait_val = EN_FEW_WAIT_VAL;
+ if (!sc->clk_dis_wait_val)
+ sc->clk_dis_wait_val = CLK_DIS_WAIT_VAL;
+
+ val = sc->en_rest_wait_val << EN_REST_WAIT_SHIFT |
+ sc->en_few_wait_val << EN_FEW_WAIT_SHIFT |
+ sc->clk_dis_wait_val << CLK_DIS_WAIT_SHIFT;
+
  ret = regmap_update_bits(sc->regmap, sc->gdscr, mask, val);
  if (ret)
  return ret;

drivers/clk/qcom/gdsc.h

@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Copyright (c) 2015, 2017-2018, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2015, 2017-2018, 2022, The Linux Foundation. All rights reserved.
  */
 
 #ifndef __QCOM_GDSC_H__
@@ -22,6 +22,9 @@ struct reset_controller_dev;
  * @cxcs: offsets of branch registers to toggle mem/periph bits in
  * @cxc_count: number of @cxcs
  * @pwrsts: Possible powerdomain power states
+ * @en_rest_wait_val: transition delay value for receiving enr ack signal
+ * @en_few_wait_val: transition delay value for receiving enf ack signal
+ * @clk_dis_wait_val: transition delay value for halting clock
  * @resets: ids of resets associated with this gdsc
  * @reset_count: number of @resets
  * @rcdev: reset controller
@@ -36,6 +39,9 @@ struct gdsc {
  unsigned int clamp_io_ctrl;
  unsigned int *cxcs;
  unsigned int cxc_count;
+ unsigned int en_rest_wait_val;
+ unsigned int en_few_wait_val;
+ unsigned int clk_dis_wait_val;
  const u8 pwrsts;
 /* Powerdomain allowable state bitfields */
 #define PWRSTS_OFF BIT(0)