soc/tegra: regulators: Prepare for suspend

Depending on hardware version, Tegra SoC may require a higher voltages
during resume from system suspend, otherwise hardware will crash. Set
SoC voltages to a nominal levels during suspend.

Link: https://lore.kernel.org/all/a8280b5b-7347-8995-c97b-10b798cdf057@gmail.com/
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

1 files changed, 99 insertions, 0 deletions

diff --git a/drivers/soc/tegra/regulators-tegra20.c b/drivers/soc/tegra/regulators-tegra20.c
index b8ce9fd0650d..6a2f90ab9d3e 100644
--- a/drivers/soc/tegra/regulators-tegra20.c
+++ b/drivers/soc/tegra/regulators-tegra20.c
@@ -16,7 +16,9 @@
 #include <linux/regulator/coupler.h>
 #include <linux/regulator/driver.h>
 #include <linux/regulator/machine.h>
+#include <linux/suspend.h>
 
+#include <soc/tegra/fuse.h>
 #include <soc/tegra/pmc.h>
 
 struct tegra_regulator_coupler {
@@ -25,9 +27,12 @@ struct tegra_regulator_coupler {
 	struct regulator_dev *cpu_rdev;
 	struct regulator_dev *rtc_rdev;
 	struct notifier_block reboot_notifier;
+	struct notifier_block suspend_notifier;
 	int core_min_uV, cpu_min_uV;
 	bool sys_reboot_mode_req;
 	bool sys_reboot_mode;
+	bool sys_suspend_mode_req;
+	bool sys_suspend_mode;
 };
 
 static inline struct tegra_regulator_coupler *
@@ -105,6 +110,28 @@ static int tegra20_core_rtc_max_spread(struct regulator_dev *core_rdev,
 	return 150000;
 }
 
+static int tegra20_cpu_nominal_uV(void)
+{
+	switch (tegra_sku_info.soc_speedo_id) {
+	case 0:
+		return 1100000;
+	case 1:
+		return 1025000;
+	default:
+		return 1125000;
+	}
+}
+
+static int tegra20_core_nominal_uV(void)
+{
+	switch (tegra_sku_info.soc_speedo_id) {
+	default:
+		return 1225000;
+	case 2:
+		return 1300000;
+	}
+}
+
 static int tegra20_core_rtc_update(struct tegra_regulator_coupler *tegra,
 				   struct regulator_dev *core_rdev,
 				   struct regulator_dev *rtc_rdev,
@@ -144,6 +171,11 @@ static int tegra20_core_rtc_update(struct tegra_regulator_coupler *tegra,
 	if (err)
 		return err;
 
+	/* prepare voltage level for suspend */
+	if (tegra->sys_suspend_mode)
+		core_min_uV = clamp(tegra20_core_nominal_uV(),
+				    core_min_uV, core_max_uV);
+
 	core_uV = regulator_get_voltage_rdev(core_rdev);
 	if (core_uV < 0)
 		return core_uV;
@@ -279,6 +311,11 @@ static int tegra20_cpu_voltage_update(struct tegra_regulator_coupler *tegra,
 	if (tegra->sys_reboot_mode)
 		cpu_min_uV = max(cpu_min_uV, tegra->cpu_min_uV);
 
+	/* prepare voltage level for suspend */
+	if (tegra->sys_suspend_mode)
+		cpu_min_uV = clamp(tegra20_cpu_nominal_uV(),
+				   cpu_min_uV, cpu_max_uV);
+
 	if (cpu_min_uV > cpu_uV) {
 		err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
 					      cpu_uV, cpu_min_uV);
@@ -320,6 +357,7 @@ static int tegra20_regulator_balance_voltage(struct regulator_coupler *coupler,
 	}
 
 	tegra->sys_reboot_mode = READ_ONCE(tegra->sys_reboot_mode_req);
+	tegra->sys_suspend_mode = READ_ONCE(tegra->sys_suspend_mode_req);
 
 	if (rdev == cpu_rdev)
 		return tegra20_cpu_voltage_update(tegra, cpu_rdev,
@@ -334,6 +372,63 @@ static int tegra20_regulator_balance_voltage(struct regulator_coupler *coupler,
 	return -EPERM;
 }
 
+static int tegra20_regulator_prepare_suspend(struct tegra_regulator_coupler *tegra,
+					     bool sys_suspend_mode)
+{
+	int err;
+
+	if (!tegra->core_rdev || !tegra->rtc_rdev || !tegra->cpu_rdev)
+		return 0;
+
+	/*
+	 * All power domains are enabled early during resume from suspend
+	 * by GENPD core.  Domains like VENC may require a higher voltage
+	 * when enabled during resume from suspend.  This also prepares
+	 * hardware for resuming from LP0.
+	 */
+
+	WRITE_ONCE(tegra->sys_suspend_mode_req, sys_suspend_mode);
+
+	err = regulator_sync_voltage_rdev(tegra->cpu_rdev);
+	if (err)
+		return err;
+
+	err = regulator_sync_voltage_rdev(tegra->core_rdev);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static int tegra20_regulator_suspend(struct notifier_block *notifier,
+				     unsigned long mode, void *arg)
+{
+	struct tegra_regulator_coupler *tegra;
+	int ret = 0;
+
+	tegra = container_of(notifier, struct tegra_regulator_coupler,
+			     suspend_notifier);
+
+	switch (mode) {
+	case PM_HIBERNATION_PREPARE:
+	case PM_RESTORE_PREPARE:
+	case PM_SUSPEND_PREPARE:
+		ret = tegra20_regulator_prepare_suspend(tegra, true);
+		break;
+
+	case PM_POST_HIBERNATION:
+	case PM_POST_RESTORE:
+	case PM_POST_SUSPEND:
+		ret = tegra20_regulator_prepare_suspend(tegra, false);
+		break;
+	}
+
+	if (ret)
+		pr_err("failed to prepare regulators: %d\n", ret);
+
+	return notifier_from_errno(ret);
+}
+
 static int tegra20_regulator_prepare_reboot(struct tegra_regulator_coupler *tegra,
 					    bool sys_reboot_mode)
 {
@@ -444,6 +539,7 @@ static struct tegra_regulator_coupler tegra20_coupler = {
 		.balance_voltage = tegra20_regulator_balance_voltage,
 	},
 	.reboot_notifier.notifier_call = tegra20_regulator_reboot,
+	.suspend_notifier.notifier_call = tegra20_regulator_suspend,
 };
 
 static int __init tegra_regulator_coupler_init(void)
@@ -456,6 +552,9 @@ static int __init tegra_regulator_coupler_init(void)
 	err = register_reboot_notifier(&tegra20_coupler.reboot_notifier);
 	WARN_ON(err);
 
+	err = register_pm_notifier(&tegra20_coupler.suspend_notifier);
+	WARN_ON(err);
+
 	return regulator_coupler_register(&tegra20_coupler.coupler);
 }
 arch_initcall(tegra_regulator_coupler_init);