[PATCH v3 8/9] clk: renesas: rzg2l-cpg: Add suspend/resume support for power domains

[Claudiu]

From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>

RZ/G3S supports deep sleep states that it can reach with the help of the
TF-A.

RZ/G3S has a few power domains (e.g. GIC) that need to be always-on while
Linux is running. These domains are initialized (and powered on) when
clock driver is probed.

As the TF-A takes control at the very last(suspend)/first(resume)
phase of configuring the deep sleep state, it can do it's own settings on
power domains.

Thus, to restore the proper Linux state, add rzg2l_cpg_resume() which
powers on the always-on domains and rzg2l_cpg_complete() which activates
the power down mode for the IPs selected through CPG_PWRDN_IP{1, 2}.

Along with it, added the suspend_check member to the RZ/G2L power domain
data structure whose purpose is to checks if a domain can be powered off
while the system is going to suspend. This is necessary for the serial
console domain which needs to be powered on if no_console_suspend is
available in bootargs.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
---

Changes in v3:
- populate pd->suspend_check on rzg2l_cpg_attach_dev() for serial
  console; due to this the rzg2l_pd_suspend_check_console() was moved
  before rzg2l_cpg_attach_dev()
- removed RZG2L_PD_F_CONSOLE define

Changes in v2:
- none; this patch is new

 drivers/clk/renesas/rzg2l-cpg.c | 68 ++++++++++++++++++++++++++++++---
 1 file changed, 63 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/renesas/rzg2l-cpg.c b/drivers/clk/renesas/rzg2l-cpg.c
index b36700f4a9f5..baf08a8cc3f0 100644
--- a/drivers/clk/renesas/rzg2l-cpg.c
+++ b/drivers/clk/renesas/rzg2l-cpg.c
@@ -15,6 +15,7 @@
 #include <linux/clk.h>
 #include <linux/clk-provider.h>
 #include <linux/clk/renesas.h>
+#include <linux/console.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/init.h>
@@ -139,6 +140,7 @@ struct rzg2l_pll5_mux_dsi_div_param {
  * @num_resets: Number of Module Resets in info->resets[]
  * @last_dt_core_clk: ID of the last Core Clock exported to DT
  * @info: Pointer to platform data
+ * @domains: generic PM domains
  * @mux_dsi_div_params: pll5 mux and dsi div parameters
  */
 struct rzg2l_cpg_priv {
@@ -155,6 +157,8 @@ struct rzg2l_cpg_priv {
 
 	const struct rzg2l_cpg_info *info;
 
+	struct generic_pm_domain **domains;
+
 	struct rzg2l_pll5_mux_dsi_div_param mux_dsi_div_params;
 };
 
@@ -1570,16 +1574,23 @@ struct rzg2l_cpg_pm_domains {
  * struct rzg2l_cpg_pd - RZ/G2L power domain data structure
  * @genpd: generic PM domain
  * @priv: pointer to CPG private data structure
+ * @suspend_check: check if domain could be powered off in suspend
  * @conf: CPG PM domain configuration info
  * @id: RZ/G2L power domain ID
  */
 struct rzg2l_cpg_pd {
 	struct generic_pm_domain genpd;
 	struct rzg2l_cpg_priv *priv;
+	int (*suspend_check)(void);
 	struct rzg2l_cpg_pm_domain_conf conf;
 	u16 id;
 };
 
+static int rzg2l_pd_suspend_check_console(void)
+{
+	return console_suspend_enabled ? 0 : -EBUSY;
+}
+
 static int rzg2l_cpg_attach_dev(struct generic_pm_domain *domain, struct device *dev)
 {
 	struct rzg2l_cpg_pd *pd = container_of(domain, struct rzg2l_cpg_pd, genpd);
@@ -1615,6 +1626,10 @@ static int rzg2l_cpg_attach_dev(struct generic_pm_domain *domain, struct device
 					error);
 				goto fail_put;
 			}
+
+			/* Add suspend check for console. */
+			if (np == of_stdout)
+				pd->suspend_check = rzg2l_pd_suspend_check_console;
 		} else {
 			of_node_put(clkspec.np);
 		}
@@ -1676,6 +1691,13 @@ static int rzg2l_cpg_power_off(struct generic_pm_domain *domain)
 	struct rzg2l_cpg_reg_conf pwrdn = pd->conf.pwrdn;
 	struct rzg2l_cpg_priv *priv = pd->priv;
 
+	if (pd->suspend_check) {
+		int ret = pd->suspend_check();
+
+		if (ret)
+			return ret;
+	}
+
 	/* Set MSTOP. */
 	if (mstop.mask)
 		writel(mstop.mask | (mstop.mask << 16), priv->base + mstop.off);
@@ -1687,8 +1709,9 @@ static int rzg2l_cpg_power_off(struct generic_pm_domain *domain)
 	return 0;
 }
 
-static int __init rzg2l_cpg_pd_setup(struct rzg2l_cpg_pd *pd, bool always_on)
+static int __init rzg2l_cpg_pd_setup(struct rzg2l_cpg_pd *pd, u32 flags)
 {
+	bool always_on = !!(flags & RZG2L_PD_F_ALWAYS_ON);
 	struct dev_power_governor *governor;
 
 	pd->genpd.flags |= GENPD_FLAG_PM_CLK | GENPD_FLAG_ACTIVE_WAKEUP;
@@ -1719,7 +1742,7 @@ static int __init rzg2l_cpg_add_clk_domain(struct rzg2l_cpg_priv *priv)
 
 	pd->genpd.name = np->name;
 	pd->priv = priv;
-	ret = rzg2l_cpg_pd_setup(pd, true);
+	ret = rzg2l_cpg_pd_setup(pd, RZG2L_PD_F_ALWAYS_ON);
 	if (ret)
 		return ret;
 
@@ -1778,13 +1801,13 @@ static int __init rzg2l_cpg_add_pm_domains(struct rzg2l_cpg_priv *priv)
 	domains->onecell_data.domains = domains->domains;
 	domains->onecell_data.num_domains = info->num_pm_domains;
 	domains->onecell_data.xlate = rzg2l_cpg_pm_domain_xlate;
+	priv->domains = domains->domains;
 
 	ret = devm_add_action_or_reset(dev, rzg2l_cpg_genpd_remove, &domains->onecell_data);
 	if (ret)
 		return ret;
 
 	for (unsigned int i = 0; i < info->num_pm_domains; i++) {
-		bool always_on = !!(info->pm_domains[i].flags & RZG2L_PD_F_ALWAYS_ON);
 		struct rzg2l_cpg_pd *pd;
 
 		pd = devm_kzalloc(dev, sizeof(*pd), GFP_KERNEL);
@@ -1796,11 +1819,11 @@ static int __init rzg2l_cpg_add_pm_domains(struct rzg2l_cpg_priv *priv)
 		pd->id = info->pm_domains[i].id;
 		pd->priv = priv;
 
-		ret = rzg2l_cpg_pd_setup(pd, always_on);
+		ret = rzg2l_cpg_pd_setup(pd, info->pm_domains[i].flags);
 		if (ret)
 			return ret;
 
-		if (always_on) {
+		if (info->pm_domains[i].flags & RZG2L_PD_F_ALWAYS_ON) {
 			ret = rzg2l_cpg_power_on(&pd->genpd);
 			if (ret)
 				return ret;
@@ -1890,9 +1913,43 @@ static int __init rzg2l_cpg_probe(struct platform_device *pdev)
 	if (error)
 		return error;
 
+	dev_set_drvdata(dev, priv);
+
+	return 0;
+}
+
+static int rzg2l_cpg_resume(struct device *dev)
+{
+	struct rzg2l_cpg_priv *priv = dev_get_drvdata(dev);
+	const struct rzg2l_cpg_info *info = priv->info;
+
+	/* Power on always ON domains. */
+	for (unsigned int i = 0; i < info->num_pm_domains; i++) {
+		if (info->pm_domains[i].flags & RZG2L_PD_F_ALWAYS_ON) {
+			int ret = rzg2l_cpg_power_on(priv->domains[i]);
+
+			if (ret)
+				return ret;
+		}
+	}
+
 	return 0;
 }
 
+static void rzg2l_cpg_complete(struct device *dev)
+{
+	struct rzg2l_cpg_priv *priv = dev_get_drvdata(dev);
+
+	/* Prepare for power down the BUSes in power down mode. */
+	if (priv->info->pm_domain_pwrdn_mstop)
+		writel(CPG_PWRDN_MSTOP_ENABLE, priv->base + CPG_PWRDN_MSTOP);
+}
+
+static const struct dev_pm_ops rzg2l_cpg_pm_ops = {
+	NOIRQ_SYSTEM_SLEEP_PM_OPS(NULL, rzg2l_cpg_resume)
+	.complete = rzg2l_cpg_complete,
+};
+
 static const struct of_device_id rzg2l_cpg_match[] = {
 #ifdef CONFIG_CLK_R9A07G043
 	{
@@ -1931,6 +1988,7 @@ static struct platform_driver rzg2l_cpg_driver = {
 	.driver		= {
 		.name	= "rzg2l-cpg",
 		.of_match_table = rzg2l_cpg_match,
+		.pm	= pm_sleep_ptr(&rzg2l_cpg_pm_ops),
 	},
 };
 
-- 
2.39.2