LinuxTV Patchwork [2/5] ACPI: Add a convenience function to tell a device is suspended in probe

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Submitter Sakari Ailus
Date May 10, 2019, 10:09 a.m.
Message ID <20190510100930.14641-3-sakari.ailus@linux.intel.com>
Download mbox | patch
Permalink /patch/56099/
State New
Headers show

Comments

Sakari Ailus - May 10, 2019, 10:09 a.m.
Add a convenience function to tell whether a device is suspended for probe
or remove, for busses where the custom is that drivers don't need to
resume devices in probe, or suspend them in their remove handlers.

Returns false on non-ACPI systems.

Suggested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/acpi/device_pm.c | 33 +++++++++++++++++++++++++++++++++
 include/linux/acpi.h     |  5 +++++
 2 files changed, 38 insertions(+)

Patch

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index ca2409a30d26d..774bf4380afd3 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -1287,4 +1287,37 @@  int acpi_dev_pm_attach(struct device *dev, bool power_on)
 	return 1;
 }
 EXPORT_SYMBOL_GPL(acpi_dev_pm_attach);
+
+/**
+ * acpi_dev_powered_off_for_probe - Tell if a device is powered off for probe
+ * @dev: The device
+ *
+ * Tell whether a given device has not been powered on for probe or remove.
+ *
+ * Drivers of devices on certain busses such as I²C can generally assume (on
+ * ACPI based systems) that the devices they control are powered on without
+ * driver having to do anything about it. Using struct device_driver.probe_off
+ * and "avoid-power-probe" property, this can be negated and the driver has full
+ * control of the device power management. Always returns false on non-ACPI
+ * based systems. True is returned on ACPI based systems iff the device is
+ * powered off.
+ */
+bool acpi_dev_powered_off_for_probe(struct device *dev)
+{
+	int power_state;
+	int ret;
+
+	if (!is_acpi_device_node(dev_fwnode(dev)))
+		return false;
+
+	ret = acpi_device_get_power(ACPI_COMPANION(dev), &power_state);
+	if (ret) {
+		dev_warn(dev, "Cannot obtain power state (%d)\n", ret);
+		return false;
+	}
+
+	return power_state != ACPI_STATE_D0;
+}
+EXPORT_SYMBOL_GPL(acpi_dev_powered_off_for_probe);
+
 #endif /* CONFIG_PM */
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index e22c237be46ae..fc6b97aadcf17 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -913,6 +913,7 @@  int acpi_dev_resume(struct device *dev);
 int acpi_subsys_runtime_suspend(struct device *dev);
 int acpi_subsys_runtime_resume(struct device *dev);
 int acpi_dev_pm_attach(struct device *dev, bool power_on);
+bool acpi_dev_powered_off_for_probe(struct device *dev);
 #else
 static inline int acpi_dev_runtime_suspend(struct device *dev) { return 0; }
 static inline int acpi_dev_runtime_resume(struct device *dev) { return 0; }
@@ -922,6 +923,10 @@  static inline int acpi_dev_pm_attach(struct device *dev, bool power_on)
 {
 	return 0;
 }
+static inline bool acpi_dev_powered_off_for_probe(struct device *dev)
+{
+	return false;
+}
 #endif
 
 #if defined(CONFIG_ACPI) && defined(CONFIG_PM_SLEEP)

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