MLK-21287 soc: imx: keep resource power ON if subdomain is wakeup source

The power mode operation ONLY checks whether the resource being
powered OFF is a wakeup source, and skip power OFF operation if
it is a wakeup source, but it does NOT consider the power tree
status, if any of its children is a wakeup source, it needs to
be kept powered ON for its children's wakeup capability.

For example, on i.MX8QXP, CAN1 shares CAN0's power, if CAN1 is
enabled as wakeup source, CAN0's power needs to be ON even it
is NOT a wakeup source, this patch adds support for such scenario.

As it uses recursion, to avoid overhead during runtime power
management, introduce a variable to make sure this logic is ONLY
enabled during suspend/resume.

The generic power domain framework for handling device power
according to wakeup status does NOT consider the virtual devices,
e.g., if debug uart is enabled as wakeup source, the device wakeup
capability check for uart device returns false, ONLY the ttydev has
wakeup capability, that will cause resume_needed() return false
and uart device power will be OFF even its child device "ttydev" is
enabeld as wakeup source.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Tested-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Reviewed-by: Bai Ping <ping.bai@nxp.com>

drivers/soc/imx/pm-domains.c

@@ -31,6 +31,7 @@
 #include <linux/pm_clock.h>
 #include <linux/slab.h>
 #include <linux/syscore_ops.h>
+#include <linux/suspend.h>
 
 #include <soc/imx/fsl_sip.h>
 #include <soc/imx8/sc/sci.h>
@@ -43,6 +44,7 @@ static sc_rsrc_t rsrc_debug_console;
 #define IMX8_WU_MAX_IRQS	(((SC_R_LAST + 31) / 32 ) * 32 )
 static sc_rsrc_t irq2rsrc[IMX8_WU_MAX_IRQS];
 static sc_rsrc_t wakeup_rsrc_id[IMX8_WU_MAX_IRQS / 32];
+static bool check_subdomain_wakeup;
 static DEFINE_SPINLOCK(imx8_wu_lock);
 static DEFINE_MUTEX(rsrc_pm_list_lock);
 
@@ -57,6 +59,27 @@ struct clk_stat {
 	unsigned long rate;
 };
 
+static bool is_resume_needed(struct generic_pm_domain *domain)
+{
+	struct gpd_link *link;
+	struct imx8_pm_domain *pd;
+	int ret;
+
+	pd = container_of(domain, struct imx8_pm_domain, pd);
+
+	/* keep resource power on if it is a wakeup source */
+	if ((1 << pd->rsrc_id % 32) & wakeup_rsrc_id[pd->rsrc_id / 32])
+		return true;
+
+	list_for_each_entry(link, &domain->master_links, master_node) {
+		ret = is_resume_needed(link->slave);
+		if (ret)
+			return ret;
+	}
+
+	return false;
+}
+
 static int imx8_pd_power(struct generic_pm_domain *domain, bool power_on)
 {
 	struct imx8_pm_domain *pd;
@@ -72,10 +95,9 @@ static int imx8_pd_power(struct generic_pm_domain *domain, bool power_on)
 		!console_suspend_enabled && !power_on)
 		return 0;
 
-	/* keep resource power on if it is a wakeup source */
-	if (!power_on && ((1 << pd->rsrc_id % 32) &
-		wakeup_rsrc_id[pd->rsrc_id / 32]))
-		return 0;
+	if (!power_on && check_subdomain_wakeup)
+		if (is_resume_needed(domain))
+			return 0;
 
 	sci_err = sc_pm_set_resource_power_mode(pm_ipc_handle, pd->rsrc_id,
 		(power_on) ? SC_PM_PW_MODE_ON :
@@ -300,6 +322,21 @@ struct syscore_ops imx8_pm_domains_syscore_ops = {
 	.suspend = imx8_pm_domains_suspend,
 };
 
+static int imx8_power_domain_pm_notify(struct notifier_block *nb, unsigned long event,
+	void *dummy)
+{
+	if (event == PM_SUSPEND_PREPARE)
+		check_subdomain_wakeup = true;
+	else if (event == PM_POST_SUSPEND)
+		check_subdomain_wakeup = false;
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block imx8_power_domain_pm_notifier = {
+	.notifier_call = imx8_power_domain_pm_notify,
+};
+
 static void imx8_pd_setup(struct imx8_pm_domain *pd)
 {
 	pd->pd.states = kzalloc(2 * sizeof(struct genpd_power_state), GFP_KERNEL);
@@ -411,6 +448,7 @@ static int __init imx8_init_pm_domains(void)
 
 	sci_err = sc_ipc_open(&pm_ipc_handle, mu_id);
 	register_syscore_ops(&imx8_pm_domains_syscore_ops);
+	register_pm_notifier(&imx8_power_domain_pm_notifier);
 
 	return 0;
 }