pmdomain: core: Add GENPD_FLAG_DEV_NAME_FW flag

Introduce GENPD_FLAG_DEV_NAME_FW flag which instructs genpd to generate
an unique device name using ida. It is aimed to be used by genpd providers
which derive their names directly from FW making them susceptible to
debugfs node creation failures.

Reported-by: Johan Hovold <[e-mail]>
Closes: https://lore.kernel.org/lkml/[e-mail]/
Fixes: 718072ceb211 ("PM: domains: create debugfs nodes when adding power domains")
Suggested-by: Ulf Hansson <[e-mail]>
Suggested-by: Dmitry Baryshkov <[e-mail]>
Signed-off-by: Sibi Sankar <[e-mail]>
Cc: [e-mail]
Message-ID: <[e-mail]>
Signed-off-by: Ulf Hansson <[e-mail]>

drivers/pmdomain/core.c

···
 #define pr_fmt(fmt) "PM: " fmt
 
 #include <linux/delay.h>
+#include <linux/idr.h>
 #include <linux/kernel.h>
 #include <linux/io.h>
 #include <linux/platform_device.h>
···
 #include <linux/export.h>
 #include <linux/cpu.h>
 #include <linux/debugfs.h>
+
+/* Provides a unique ID for each genpd device */
+static DEFINE_IDA(genpd_ida);
 
 #define GENPD_RETRY_MAX_MS	250		/* Approximate */
 
···
 #define genpd_is_cpu_domain(genpd)	(genpd->flags & GENPD_FLAG_CPU_DOMAIN)
 #define genpd_is_rpm_always_on(genpd)	(genpd->flags & GENPD_FLAG_RPM_ALWAYS_ON)
 #define genpd_is_opp_table_fw(genpd)	(genpd->flags & GENPD_FLAG_OPP_TABLE_FW)
+#define genpd_is_dev_name_fw(genpd)	(genpd->flags & GENPD_FLAG_DEV_NAME_FW)
 
 static inline bool irq_safe_dev_in_sleep_domain(struct device *dev,
 		const struct generic_pm_domain *genpd)
···
 
 	if (ret)
 		dev_warn_once(dev, "PM domain %s will not be powered off\n",
-				genpd->name);
+			      dev_name(&genpd->dev));
 
 	return ret;
 }
···
 	if (!genpd_debugfs_dir)
 		return;
 
-	debugfs_lookup_and_remove(genpd->name, genpd_debugfs_dir);
+	debugfs_lookup_and_remove(dev_name(&genpd->dev), genpd_debugfs_dir);
 }
 
 static void genpd_update_accounting(struct generic_pm_domain *genpd)
···
 	genpd->states[state_idx].power_on_latency_ns = elapsed_ns;
 	genpd->gd->max_off_time_changed = true;
 	pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
-		 genpd->name, "on", elapsed_ns);
+		 dev_name(&genpd->dev), "on", elapsed_ns);
 
 out:
 	raw_notifier_call_chain(&genpd->power_notifiers, GENPD_NOTIFY_ON, NULL);
···
 	genpd->states[state_idx].power_off_latency_ns = elapsed_ns;
 	genpd->gd->max_off_time_changed = true;
 	pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
-		 genpd->name, "off", elapsed_ns);
+		 dev_name(&genpd->dev), "off", elapsed_ns);
 
 out:
 	raw_notifier_call_chain(&genpd->power_notifiers, GENPD_NOTIFY_OFF,
···
 
 	if (ret) {
 		dev_warn(dev, "failed to add notifier for PM domain %s\n",
-			 genpd->name);
+			 dev_name(&genpd->dev));
 		return ret;
 	}
 
···
 
 	if (ret) {
 		dev_warn(dev, "failed to remove notifier for PM domain %s\n",
-			 genpd->name);
+			 dev_name(&genpd->dev));
 		return ret;
 	}
 
···
 	 */
 	if (!genpd_is_irq_safe(genpd) && genpd_is_irq_safe(subdomain)) {
 		WARN(1, "Parent %s of subdomain %s must be IRQ safe\n",
-				genpd->name, subdomain->name);
+		     dev_name(&genpd->dev), subdomain->name);
 		return -EINVAL;
 	}
 
···
 
 	if (!list_empty(&subdomain->parent_links) || subdomain->device_count) {
 		pr_warn("%s: unable to remove subdomain %s\n",
-			genpd->name, subdomain->name);
+			dev_name(&genpd->dev), subdomain->name);
 		ret = -EBUSY;
 		goto out;
 	}
···
 	genpd->status = is_off ? GENPD_STATE_OFF : GENPD_STATE_ON;
 	genpd->device_count = 0;
 	genpd->provider = NULL;
+	genpd->device_id = -ENXIO;
 	genpd->has_provider = false;
 	genpd->accounting_time = ktime_get_mono_fast_ns();
 	genpd->domain.ops.runtime_suspend = genpd_runtime_suspend;
···
 		return ret;
 
 	device_initialize(&genpd->dev);
-	dev_set_name(&genpd->dev, "%s", genpd->name);
+
+	if (!genpd_is_dev_name_fw(genpd)) {
+		dev_set_name(&genpd->dev, "%s", genpd->name);
+	} else {
+		ret = ida_alloc(&genpd_ida, GFP_KERNEL);
+		if (ret < 0) {
+			put_device(&genpd->dev);
+			return ret;
+		}
+		genpd->device_id = ret;
+		dev_set_name(&genpd->dev, "%s_%u", genpd->name, genpd->device_id);
+	}
 
 	mutex_lock(&gpd_list_lock);
 	list_add(&genpd->gpd_list_node, &gpd_list);
···
 
 	if (genpd->has_provider) {
 		genpd_unlock(genpd);
-		pr_err("Provider present, unable to remove %s\n", genpd->name);
+		pr_err("Provider present, unable to remove %s\n", dev_name(&genpd->dev));
 		return -EBUSY;
 	}
 
 	if (!list_empty(&genpd->parent_links) || genpd->device_count) {
 		genpd_unlock(genpd);
-		pr_err("%s: unable to remove %s\n", __func__, genpd->name);
+		pr_err("%s: unable to remove %s\n", __func__, dev_name(&genpd->dev));
 		return -EBUSY;
 	}
 
···
 	genpd_unlock(genpd);
 	genpd_debug_remove(genpd);
 	cancel_work_sync(&genpd->power_off_work);
+	if (genpd->device_id != -ENXIO)
+		ida_free(&genpd_ida, genpd->device_id);
 	genpd_free_data(genpd);
 
-	pr_debug("%s: removed %s\n", __func__, genpd->name);
+	pr_debug("%s: removed %s\n", __func__, dev_name(&genpd->dev));
 
 	return 0;
 }
···
 	else
 		snprintf(state, sizeof(state), "%s",
 			 status_lookup[genpd->status]);
-	seq_printf(s, "%-30s  %-30s  %u", genpd->name, state, genpd->performance_state);
+	seq_printf(s, "%-30s  %-30s  %u", dev_name(&genpd->dev), state, genpd->performance_state);
 
 	/*
 	 * Modifications on the list require holding locks on both
 	 * parent and child, so we are safe.
-	 * Also genpd->name is immutable.
+	 * Also the device name is immutable.
 	 */
 	list_for_each_entry(link, &genpd->parent_links, parent_node) {
 		if (list_is_first(&link->parent_node, &genpd->parent_links))
···
 	if (!genpd_debugfs_dir)
 		return;
 
-	d = debugfs_create_dir(genpd->name, genpd_debugfs_dir);
+	d = debugfs_create_dir(dev_name(&genpd->dev), genpd_debugfs_dir);
 
 	debugfs_create_file("current_state", 0444,
 			    d, genpd, &status_fops);

include/linux/pm_domain.h

···
  * GENPD_FLAG_OPP_TABLE_FW:	The genpd provider supports performance states,
  *				but its corresponding OPP tables are not
  *				described in DT, but are given directly by FW.
+ *
+ * GENPD_FLAG_DEV_NAME_FW:	Instructs genpd to generate an unique device name
+ *				using ida. It is used by genpd providers which
+ *				get their genpd-names directly from FW.
  */
 #define GENPD_FLAG_PM_CLK	 (1U << 0)
 #define GENPD_FLAG_IRQ_SAFE	 (1U << 1)
···
 #define GENPD_FLAG_RPM_ALWAYS_ON (1U << 5)
 #define GENPD_FLAG_MIN_RESIDENCY (1U << 6)
 #define GENPD_FLAG_OPP_TABLE_FW	 (1U << 7)
+#define GENPD_FLAG_DEV_NAME_FW	 (1U << 8)
 
 enum gpd_status {
 	GENPD_STATE_ON = 0,	/* PM domain is on */
···
 	atomic_t sd_count;	/* Number of subdomains with power "on" */
 	enum gpd_status status;	/* Current state of the domain */
 	unsigned int device_count;	/* Number of devices */
+	unsigned int device_id;		/* unique device id */
 	unsigned int suspended_count;	/* System suspend device counter */
 	unsigned int prepared_count;	/* Suspend counter of prepared devices */
 	unsigned int performance_state;	/* Aggregated max performance state */