[PATCH] PM / Domains: add debugfs listing of struct generic_pm_domain-s

[Maciej Matraszek]

Add /sys/kernel/debug/pm_genpd/pm_genpd_summary file, which
lists power domains in the system, their statuses and attached devices,
resembling /sys/kernel/debug/clk/clk_summary.

Currently it is impossible to inspect (from userland) whether
a power domain is on or off. And, if it is on, which device blocks it
from powering down. This change allows developers working on
embedded devices power efficiency to list all necessary information
about generic power domains in one place.

The content of pm_genpd/pm_genpd_summary file is generated by iterating
over all generic power domain in the system, and, for each,
over registered devices.

Example output:
$ cat  /sys/kernel/debug/pm_genpd/pm_genpd_summary
    domain                      status         slaves
           /device                                      runtime status
----------------------------------------------------------------------
isp-power-domain                off
    /devices/soc/12180000.fimc-is                       suspended
    /devices/soc/12180000.fimc-is/120a0000.fimc-lite    suspended
lcd0-power-domain               on
    /devices/soc/11c80000.dsi                           active
    /devices/soc/11c00000.fimd                          active
    /devices/soc/11e20000.sysmmu                        suspended
g3d-power-domain                off
    /devices/soc/13001000.gpu                           suspended
mfc-power-domain                off
    /devices/soc/13400000.mfc-codec                     suspended
    /devices/soc/13620000.sysmmu                        suspended
cam-power-domain                off
    /devices/soc/11830000.jpeg-codec                    suspended
    /devices/soc/11a60000.sysmmu                        suspended
    /devices/soc/12180000.fimc-is/120c0000.csis         suspended

To enable this feature, compile the kernel with debugfs
and CONFIG_PM_ADVANCED_DEBUG enabled.

Signed-off-by: Maciej Matraszek <m.matraszek@xxxxxxxxxxx>
---
 drivers/base/power/domain.c | 153 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index eee55c1e5fde..d1aa731ba0db 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -2189,3 +2189,156 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
 	list_add(&genpd->gpd_list_node, &gpd_list);
 	mutex_unlock(&gpd_list_lock);
 }
+
+
+/***        debugfs support        ***/
+
+#ifdef CONFIG_PM_ADVANCED_DEBUG
+#include <linux/pm.h>
+#include <linux/device.h>
+#include <linux/debugfs.h>
+#include <linux/kobject.h>
+static struct dentry *pm_genpd_debugfs_dir;
+
+/*
+ * TODO: This function is a slightly modified version of rtpm_status_show
+ * from sysfs.c, but dependencies between PM_GENERIC_DOMAINS and PM_RUNTIME
+ * are too loose to generalize it.
+ */
+#ifdef CONFIG_PM_RUNTIME
+static void rtpm_status_str(struct seq_file *s, struct device *dev)
+{
+	static const char * const status_lookup[] = {
+		[RPM_ACTIVE] = "active",
+		[RPM_RESUMING] = "resuming",
+		[RPM_SUSPENDED] = "suspended",
+		[RPM_SUSPENDING] = "suspending"
+	};
+	const char *p = "";
+
+	if (dev->power.runtime_error)
+		p = "error";
+	else if (dev->power.disable_depth)
+		p = "unsupported";
+	else if (dev->power.runtime_status < ARRAY_SIZE(status_lookup))
+		p = status_lookup[dev->power.runtime_status];
+	else
+		WARN_ON(1);
+
+	seq_puts(s, p);
+}
+#else
+static void rtpm_status_str(struct seq_file *s, struct device *dev)
+{
+	seq_puts(s, "active");
+}
+#endif
+
+static int pm_genpd_summary_one(struct seq_file *s,
+		struct generic_pm_domain *gpd)
+{
+	static const char * const status_lookup[] = {
+		[GPD_STATE_ACTIVE] = "on",
+		[GPD_STATE_WAIT_MASTER] = "wait-master",
+		[GPD_STATE_BUSY] = "busy",
+		[GPD_STATE_REPEAT] = "off-in-progress",
+		[GPD_STATE_POWER_OFF] = "off"
+	};
+	struct pm_domain_data *pm_data;
+	const char *kobj_path;
+	struct gpd_link *link;
+	int ret;
+
+	ret = mutex_lock_interruptible(&gpd->lock);
+	if (ret)
+		return -ERESTARTSYS;
+
+	if (WARN_ON(gpd->status >= ARRAY_SIZE(status_lookup)))
+		goto exit;
+	seq_printf(s, "%-30s  %-15s  ", gpd->name, status_lookup[gpd->status]);
+
+	/*
+	 * Modifications on the list require holding locks on both
+	 * master and slave, so we are safe.
+	 * Also gpd->name is immutable.
+	 */
+	list_for_each_entry(link, &gpd->master_links, master_node) {
+		seq_printf(s, "%s", link->slave->name);
+		if (!list_is_last(&link->master_node, &gpd->master_links))
+			seq_puts(s, ", ");
+	}
+
+	list_for_each_entry(pm_data, &gpd->dev_list, list_node) {
+		kobj_path = kobject_get_path(&pm_data->dev->kobj, GFP_KERNEL);
+		if (kobj_path == NULL)
+			continue;
+
+		seq_printf(s, "\n    %-50s  ", kobj_path);
+		rtpm_status_str(s, pm_data->dev);
+		kfree(kobj_path);
+	}
+
+	seq_puts(s, "\n");
+exit:
+	mutex_unlock(&gpd->lock);
+
+	return 0;
+}
+
+static int pm_genpd_summary_show(struct seq_file *s, void *data)
+{
+	struct generic_pm_domain *gpd;
+	int ret = 0;
+
+	seq_puts(s, "    domain                      status         slaves\n");
+	seq_puts(s, "           /device                                      runtime status\n");
+	seq_puts(s, "----------------------------------------------------------------------\n");
+
+	ret = mutex_lock_interruptible(&gpd_list_lock);
+	if (ret)
+		return -ERESTARTSYS;
+
+	list_for_each_entry(gpd, &gpd_list, gpd_list_node) {
+		ret = pm_genpd_summary_one(s, gpd);
+		if (ret)
+			break;
+	}
+	mutex_unlock(&gpd_list_lock);
+
+	return ret;
+}
+
+static int pm_genpd_summary_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, pm_genpd_summary_show, inode->i_private);
+}
+
+static const struct file_operations pm_genpd_summary_fops = {
+	.open = pm_genpd_summary_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static int __init pm_genpd_debug_init(void)
+{
+	struct dentry *d;
+
+	pm_genpd_debugfs_dir = debugfs_create_dir("pm_genpd", NULL);
+
+	/* No debugfs */
+	if (IS_ERR(pm_genpd_debugfs_dir))
+		return PTR_ERR(pm_genpd_debugfs_dir);
+
+	if (!pm_genpd_debugfs_dir)
+		return -ENOMEM;
+
+	d = debugfs_create_file("pm_genpd_summary", S_IRUGO,
+			pm_genpd_debugfs_dir, NULL, &pm_genpd_summary_fops);
+	if (!d)
+		return -ENOMEM;
+
+	return 0;
+}
+late_initcall(pm_genpd_debug_init);
+#endif /* CONFIG_PM_ADVANCED_DEBUG */
-- 
1.9.1

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