[PATCH v5 1/6] i2c: Allow driver to manage the device's power state during probe

Sakari Ailus
2020-08-10T14:25:41Z

Enable drivers to tell ACPI that there's no need to power on a device for
probe. Drivers should still perform this by themselves if there's a need
to. In some cases powering on the device during probe is undesirable, and
this change enables a driver to choose what fits best for it.

Add a field called "flags" into struct i2c_driver for driver flags, and a
flag I2C_DRV_FL_ALLOW_LOW_POWER_PROBE to tell a driver supports probe in
low power state.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
drivers/i2c/i2c-core-base.c | 17 ++++++++++++++---
include/linux/i2c.h | 14 ++++++++++++++
2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 34a9609f256da..cde9cf49a07e6 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -436,6 +436,14 @@ static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client)
return irq > 0 ? irq : -ENXIO;
}

+static bool allow_low_power_probe(struct device *dev)
+{
+ struct i2c_driver *driver = to_i2c_driver(dev->driver);
+
+ return driver->flags & I2C_DRV_FL_ALLOW_LOW_POWER_PROBE &&
+ device_property_present(dev, "allow-low-power-probe");
+}
+
static int i2c_device_probe(struct device *dev)
{
struct i2c_client *client = i2c_verify_client(dev);
@@ -514,7 +522,8 @@ static int i2c_device_probe(struct device *dev)
if (status < 0)
goto err_clear_wakeup_irq;

- status = dev_pm_domain_attach(&client->dev, true);
+ status = dev_pm_domain_attach(&client->dev,
+ !allow_low_power_probe(&client->dev));
if (status)
goto err_clear_wakeup_irq;

@@ -536,7 +545,8 @@ static int i2c_device_probe(struct device *dev)
return 0;

err_detach_pm_domain:
- dev_pm_domain_detach(&client->dev, true);
+ dev_pm_domain_detach(&client->dev,
+ !allow_low_power_probe(&client->dev));
err_clear_wakeup_irq:
dev_pm_clear_wake_irq(&client->dev);
device_init_wakeup(&client->dev, false);
@@ -562,7 +572,8 @@ static int i2c_device_remove(struct device *dev)
status = driver->remove(client);
}

- dev_pm_domain_detach(&client->dev, true);
+ dev_pm_domain_detach(&client->dev,
+ !allow_low_power_probe(&client->dev));

dev_pm_clear_wake_irq(&client->dev);
device_init_wakeup(&client->dev, false);
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index fc55ea41d3237..6824719c24ebe 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -11,6 +11,7 @@
#define _LINUX_I2C_H

#include <linux/acpi.h> /* for acpi_handle */
+#include <linux/bits.h>
#include <linux/mod_devicetable.h>
#include <linux/device.h> /* for struct device */
#include <linux/sched.h> /* for completion */
@@ -217,6 +218,16 @@ enum i2c_alert_protocol {
I2C_PROTOCOL_SMBUS_HOST_NOTIFY,
};

+/**
+ * enum i2c_driver_flags - Flags for an I2C device driver
+ *
+ * @I2C_DRV_FL_ALLOW_LOW_POWER_PROBE: Let the driver manage the device's power
+ * state during probe and remove
+ */
+enum i2c_driver_flags {
+ I2C_DRV_FL_ALLOW_LOW_POWER_PROBE = BIT(0),
+};
+
/**
* struct i2c_driver - represent an I2C device driver
* @class: What kind of i2c device we instantiate (for detect)
@@ -231,6 +242,7 @@ enum i2c_alert_protocol {
* @detect: Callback for device detection
* @address_list: The I2C addresses to probe (for detect)
* @clients: List of detected clients we created (for i2c-core use only)
+ * @flags: A bitmask of flags defined in &enum i2c_driver_flags
*
* The driver.owner field should be set to the module owner of this driver.
* The driver.name field should be set to the name of this driver.
@@ -289,6 +301,8 @@ struct i2c_driver {
int (*detect)(struct i2c_client *client, struct i2c_board_info *info);
const unsigned short *address_list;
struct list_head clients;
+
+ unsigned int flags;
};
#define to_i2c_driver(d) container_of(d, struct i2c_driver, driver)

--
2.20.1