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Subject[PATCH v10 2/7] i2c: Allow an ACPI driver to manage the device's power state during probe
Date
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>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
---
drivers/i2c/i2c-core-acpi.c | 10 ++++++++++
drivers/i2c/i2c-core-base.c | 9 ++++++---
include/linux/i2c.h | 19 +++++++++++++++++++
3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
index 8ceaa88dd78fb..7bab8b9126ee6 100644
--- a/drivers/i2c/i2c-core-acpi.c
+++ b/drivers/i2c/i2c-core-acpi.c
@@ -493,6 +493,16 @@ struct i2c_client *i2c_acpi_new_device(struct device *dev, int index,
}
EXPORT_SYMBOL_GPL(i2c_acpi_new_device);

+bool i2c_acpi_allow_low_power_probe(struct device *dev)
+{
+ struct i2c_driver *driver = to_i2c_driver(dev->driver);
+ struct acpi_device *adev = ACPI_COMPANION(dev);
+
+ return driver->flags & I2C_DRV_FL_ALLOW_LOW_POWER_PROBE &&
+ adev && adev->power.state_for_enumeration >= adev->power.state;
+}
+EXPORT_SYMBOL_GPL(i2c_acpi_allow_low_power_probe);
+
#ifdef CONFIG_ACPI_I2C_OPREGION
static int acpi_gsb_i2c_read_bytes(struct i2c_client *client,
u8 cmd, u8 *data, u8 data_len)
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 63ebf722a4248..87b84eee01da6 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -514,7 +514,8 @@ 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,
+ !i2c_acpi_allow_low_power_probe(dev));
if (status)
goto err_clear_wakeup_irq;

@@ -536,7 +537,8 @@ 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,
+ !i2c_acpi_allow_low_power_probe(dev));
err_clear_wakeup_irq:
dev_pm_clear_wake_irq(&client->dev);
device_init_wakeup(&client->dev, false);
@@ -563,7 +565,8 @@ static int i2c_device_remove(struct device *dev)
dev_warn(dev, "remove failed (%pe), will be ignored\n", ERR_PTR(status));
}

- dev_pm_domain_detach(&client->dev, true);
+ dev_pm_domain_detach(&client->dev,
+ !i2c_acpi_allow_low_power_probe(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 56622658b2158..1a103c5933d2f 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 ACPI 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;
+
+ u32 flags;
};
#define to_i2c_driver(d) container_of(d, struct i2c_driver, driver)

@@ -996,6 +1010,7 @@ u32 i2c_acpi_find_bus_speed(struct device *dev);
struct i2c_client *i2c_acpi_new_device(struct device *dev, int index,
struct i2c_board_info *info);
struct i2c_adapter *i2c_acpi_find_adapter_by_handle(acpi_handle handle);
+bool i2c_acpi_allow_low_power_probe(struct device *dev);
#else
static inline bool i2c_acpi_get_i2c_resource(struct acpi_resource *ares,
struct acpi_resource_i2c_serialbus **i2c)
@@ -1015,6 +1030,10 @@ static inline struct i2c_adapter *i2c_acpi_find_adapter_by_handle(acpi_handle ha
{
return NULL;
}
+static inline bool i2c_acpi_allow_low_power_probe(struct device *dev)
+{
+ return false;
+}
#endif /* CONFIG_ACPI */

#endif /* _LINUX_I2C_H */
--
2.20.1
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