i2c: smbus: add SMBus Host Notify support
SMBus Host Notify allows a slave device to act as a master on a bus to
notify the host of an interrupt. On Intel chipsets, the functionality
is directly implemented in the firmware. We just need to export a
function to call .alert() on the proper device driver.
i2c_handle_smbus_host_notify() behaves like i2c_handle_smbus_alert().
When called, it schedules a task that will be able to sleep to go through
the list of devices attached to the adapter.
The current implementation allows one Host Notification to be scheduled
while an other is running.
Tested-by: Andrew Duggan <aduggan@synaptics.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h
index 8f1b086..4ac95bb 100644
--- a/include/linux/i2c-smbus.h
+++ b/include/linux/i2c-smbus.h
@@ -23,6 +23,8 @@
#define _LINUX_I2C_SMBUS_H
#include <linux/i2c.h>
+#include <linux/spinlock.h>
+#include <linux/workqueue.h>
/**
@@ -48,4 +50,46 @@
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;
+};
+
+#if IS_ENABLED(CONFIG_I2C_SMBUS)
+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);
+#else
+static inline struct smbus_host_notify *
+i2c_setup_smbus_host_notify(struct i2c_adapter *adap)
+{
+ return NULL;
+}
+
+static inline int
+i2c_handle_smbus_host_notify(struct smbus_host_notify *host_notify,
+ unsigned short addr, unsigned int data)
+{
+ return 0;
+}
+#endif /* I2C_SMBUS */
+
#endif /* _LINUX_I2C_SMBUS_H */
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 37a45dc..fffdc27 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -128,6 +128,7 @@
enum i2c_alert_protocol {
I2C_PROTOCOL_SMBUS_ALERT,
+ I2C_PROTOCOL_SMBUS_HOST_NOTIFY,
};
/**
@@ -184,6 +185,8 @@
* The format and meaning of the data value depends on the protocol.
* For the SMBus alert protocol, there is a single bit of data passed
* as the alert response's low bit ("event flag").
+ * For the SMBus Host Notify protocol, the data corresponds to the
+ * 16-bit payload data reported by the slave device acting as master.
*/
void (*alert)(struct i2c_client *, enum i2c_alert_protocol protocol,
unsigned int data);
diff --git a/include/uapi/linux/i2c.h b/include/uapi/linux/i2c.h
index adcbef4..009e27bb 100644
--- a/include/uapi/linux/i2c.h
+++ b/include/uapi/linux/i2c.h
@@ -102,6 +102,7 @@
#define I2C_FUNC_SMBUS_WRITE_BLOCK_DATA 0x02000000
#define I2C_FUNC_SMBUS_READ_I2C_BLOCK 0x04000000 /* I2C-like block xfer */
#define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK 0x08000000 /* w/ 1-byte reg. addr. */
+#define I2C_FUNC_SMBUS_HOST_NOTIFY 0x10000000
#define I2C_FUNC_SMBUS_BYTE (I2C_FUNC_SMBUS_READ_BYTE | \
I2C_FUNC_SMBUS_WRITE_BYTE)