i2c: use an IRQ to report Host Notify events, not alert

The current SMBus Host Notify implementation relies on .alert() to
relay its notifications. However, the use cases where SMBus Host
Notify is needed currently is to signal data ready on touchpads.

This is closer to an IRQ than a custom API through .alert().
Given that the 2 touchpad manufacturers (Synaptics and Elan) that
use SMBus Host Notify don't put any data in the SMBus payload, the
concept actually matches one to one.

Benefits are multiple:
- simpler code and API: the client will just have an IRQ, and
  nothing needs to be added in the adapter beside internally
  enabling it.
- no more specific workqueue, the threading is handled by IRQ core
  directly (when required)
- no more races when removing the device (the drivers are already
  required to disable irq on remove)
- simpler handling for drivers: use plain regular IRQs
- no more dependency on i2c-smbus for i2c-i801 (and any other adapter)
- the IRQ domain is created automatically when the adapter exports
  the Host Notify capability
- the IRQ are assign only if ACPI, OF and the caller did not assign
  one already
- the domain is automatically destroyed on remove
- fewer lines of code (minus 20, yeah!)

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 0 insertions, 27 deletions

diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h
index c2e3324f9468..a1385023a29b 100644
--- a/include/linux/i2c-smbus.h
+++ b/include/linux/i2c-smbus.h
@@ -50,31 +50,4 @@ struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter,
 					 struct i2c_smbus_alert_setup *setup);
 int i2c_handle_smbus_alert(struct i2c_client *ara);
 
-/**
- * smbus_host_notify - internal structure used by the Host Notify mechanism.
- * @adapter: the I2C adapter associated with this struct
- * @work: worker used to schedule the IRQ in the slave device
- * @lock: spinlock to check if a notification is already pending
- * @pending: flag set when a notification is pending (any new notification will
- *		be rejected if pending is true)
- * @payload: the actual payload of the Host Notify event
- * @addr: the address of the slave device which raised the notification
- *
- * This struct needs to be allocated by i2c_setup_smbus_host_notify() and does
- * not need to be freed. Internally, i2c_setup_smbus_host_notify() uses a
- * managed resource to clean this up when the adapter get released.
- */
-struct smbus_host_notify {
-	struct i2c_adapter	*adapter;
-	struct work_struct	work;
-	spinlock_t		lock;
-	bool			pending;
-	u16			payload;
-	u8			addr;
-};
-
-struct smbus_host_notify *i2c_setup_smbus_host_notify(struct i2c_adapter *adap);
-int i2c_handle_smbus_host_notify(struct smbus_host_notify *host_notify,
-				 unsigned short addr, unsigned int data);
-
 #endif /* _LINUX_I2C_SMBUS_H */