drivers/base/power/sysfs.c

Source file repositories/reference/linux-study-clean/drivers/base/power/sysfs.c

File Facts

System
Linux kernel
Corpus path
drivers/base/power/sysfs.c
Extension
.c
Size
21634 bytes
Lines
836
Domain
Driver Families
Bucket
drivers/base
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

switch (dev->power.runtime_status) {
		case RPM_SUSPENDED:
			output = "suspended";
			break;
		case RPM_SUSPENDING:
			output = "suspending";
			break;
		case RPM_RESUMING:
			output = "resuming";
			break;
		case RPM_ACTIVE:
			output = "active";
			break;
		default:
			return -EIO;
		}
	}
	return sysfs_emit(buf, "%s\n", output);
}

static DEVICE_ATTR_RO(runtime_status);

static ssize_t autosuspend_delay_ms_show(struct device *dev,
					 struct device_attribute *attr,
					 char *buf)
{
	if (!dev->power.use_autosuspend)
		return -EIO;

	return sysfs_emit(buf, "%d\n", dev->power.autosuspend_delay);
}

static ssize_t autosuspend_delay_ms_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t n)
{
	long delay;

	if (!dev->power.use_autosuspend)
		return -EIO;

	if (kstrtol(buf, 10, &delay) != 0 || delay != (int) delay)
		return -EINVAL;

	device_lock(dev);
	pm_runtime_set_autosuspend_delay(dev, delay);
	device_unlock(dev);
	return n;
}

static DEVICE_ATTR_RW(autosuspend_delay_ms);

static ssize_t pm_qos_resume_latency_us_show(struct device *dev,
					     struct device_attribute *attr,
					     char *buf)
{
	s32 value = dev_pm_qos_requested_resume_latency(dev);

	if (value == 0)
		return sysfs_emit(buf, "n/a\n");
	if (value == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
		value = 0;

	return sysfs_emit(buf, "%d\n", value);
}

static ssize_t pm_qos_resume_latency_us_store(struct device *dev,
					      struct device_attribute *attr,
					      const char *buf, size_t n)
{
	s32 value;
	int ret;

	if (!kstrtos32(buf, 0, &value)) {
		/*
		 * Prevent users from writing negative or "no constraint" values
		 * directly.
		 */
		if (value < 0 || value == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
			return -EINVAL;

		if (value == 0)
			value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
	} else if (sysfs_streq(buf, "n/a")) {
		value = 0;
	} else {
		return -EINVAL;
	}

	ret = dev_pm_qos_update_request(dev->power.qos->resume_latency_req,
					value);

Annotation

Implementation Notes