soc/tegra: pmc: Add driver state syncing

Add driver state syncing that is invoked once all PMC consumers are
attached and ready. The consumers are the power domain clients.
The synchronization callback is invoked once all client drivers are
probed, the driver core handles this for us. This callback informs
PMC driver that all voltage votes are initialized by each PD client
and it's safe to begin voltage scaling of the core power domain.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
[treding@nvidia.com: squash DT backwards-compatibility patch]
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/soc/tegra/pmc.c

@@ -429,6 +429,9 @@ struct tegra_pmc {
 	struct irq_chip irq;
 
 	struct notifier_block clk_nb;
+
+	bool core_domain_state_synced;
+	bool core_domain_registered;
 };
 
 static struct tegra_pmc *pmc = &(struct tegra_pmc) {
@@ -1303,6 +1306,11 @@ static int tegra_powergate_add(struct tegra_pmc *pmc, struct device_node *np)
 	return err;
 }
 
+bool tegra_pmc_core_domain_state_synced(void)
+{
+	return pmc->core_domain_state_synced;
+}
+
 static int
 tegra_pmc_core_pd_set_performance_state(struct generic_pm_domain *genpd,
 					unsigned int level)
@@ -1370,6 +1378,8 @@ static int tegra_pmc_core_pd_add(struct tegra_pmc *pmc, struct device_node *np)
 		goto remove_genpd;
 	}
 
+	pmc->core_domain_registered = true;
+
 	return 0;
 
 remove_genpd:
@@ -3782,6 +3792,29 @@ static const struct of_device_id tegra_pmc_match[] = {
 	{ }
 };
 
+static void tegra_pmc_sync_state(struct device *dev)
+{
+	int err;
+
+	/*
+	 * Older device-trees don't have core PD, and thus, there are
+	 * no dependencies that will block the state syncing. We shouldn't
+	 * mark the domain as synced in this case.
+	 */
+	if (!pmc->core_domain_registered)
+		return;
+
+	pmc->core_domain_state_synced = true;
+
+	/* this is a no-op if core regulator isn't used */
+	mutex_lock(&pmc->powergates_lock);
+	err = dev_pm_opp_sync_regulators(dev);
+	mutex_unlock(&pmc->powergates_lock);
+
+	if (err)
+		dev_err(dev, "failed to sync regulators: %d\n", err);
+}
+
 static struct platform_driver tegra_pmc_driver = {
 	.driver = {
 		.name = "tegra-pmc",
@@ -3790,6 +3823,7 @@ static struct platform_driver tegra_pmc_driver = {
 #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_ARM)
 		.pm = &tegra_pmc_pm_ops,
 #endif
+		.sync_state = tegra_pmc_sync_state,
 	},
 	.probe = tegra_pmc_probe,
 };

include/soc/tegra/pmc.h

@@ -171,6 +171,8 @@ int tegra_io_rail_power_off(unsigned int id);
 void tegra_pmc_set_suspend_mode(enum tegra_suspend_mode mode);
 void tegra_pmc_enter_suspend_mode(enum tegra_suspend_mode mode);
 
+bool tegra_pmc_core_domain_state_synced(void);
+
 #else
 static inline int tegra_powergate_power_on(unsigned int id)
 {
@@ -227,6 +229,11 @@ static inline void tegra_pmc_enter_suspend_mode(enum tegra_suspend_mode mode)
 {
 }
 
+static inline bool tegra_pmc_core_domain_state_synced(void)
+{
+	return false;
+}
+
 #endif /* CONFIG_SOC_TEGRA_PMC */
 
 #if defined(CONFIG_SOC_TEGRA_PMC) && defined(CONFIG_PM_SLEEP)