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.
Compared to i2c_handle_smbus_alert(), it is much more convenient to
require to be able to sleep in i2c_propagate_smbus_host_notify().
device_(un)lock() in smbus_do_alert() needs to be able to sleep,
but because the address and payload are given directly by the caller
scheduling a new task would require a fifo or a lock on the current
I2C address and payload.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
---
Changes in v2:
- do the actual processing of finding the device in i2c-smbus.c
- remove the i2c-core implementations
- remove the manual toggle of SMBus Host Notify
Documentation/i2c/smbus-protocol | 3 +++
drivers/i2c/i2c-smbus.c | 36 +++++++++++++++++++++++++++++++-----
include/linux/i2c-smbus.h | 8 ++++++++
include/linux/i2c.h | 3 +++
include/uapi/linux/i2c.h | 1 +
5 files changed, 46 insertions(+), 5 deletions(-)
diff --git a/Documentation/i2c/smbus-protocol b/Documentation/i2c/smbus-protocol
index 6012b12..4e07848 100644
--- a/Documentation/i2c/smbus-protocol
+++ b/Documentation/i2c/smbus-protocol
@@ -199,6 +199,9 @@ alerting device's address.
[S] [HostAddr] [Wr] A [DevAddr] A [DataLow] A [DataHigh] A [P]
+I2C drivers for devices which can trigger SMBus Host Notify should implement
+the optional alert() callback.
+
Packet Error Checking (PEC)
===========================
diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
index abad351..c348c1a 100644
--- a/drivers/i2c/i2c-smbus.c
+++ b/drivers/i2c/i2c-smbus.c
@@ -33,7 +33,8 @@ struct i2c_smbus_alert {
struct alert_data {
unsigned short addr;
- u8 flag:1;
+ enum i2c_alert_protocol type;
+ unsigned int data;
};
/* If this is the alerting device, notify its driver */
@@ -56,8 +57,7 @@ static int smbus_do_alert(struct device *dev, void *addrp)
if (client->dev.driver) {
driver = to_i2c_driver(client->dev.driver);
if (driver->alert)
- driver->alert(client, I2C_PROTOCOL_SMBUS_ALERT,
- data->flag);
+ driver->alert(client, data->type, data->data);
else
dev_warn(&client->dev, "no driver alert()!\n");
} else
@@ -97,8 +97,9 @@ static void smbus_alert(struct work_struct *work)
if (status < 0)
break;
- data.flag = status & 1;
+ data.data = status & 1;
data.addr = status >> 1;
+ data.type = I2C_PROTOCOL_SMBUS_ALERT;
if (data.addr == prev_addr) {
dev_warn(&ara->dev, "Duplicate SMBALERT# from dev "
@@ -106,7 +107,7 @@ static void smbus_alert(struct work_struct *work)
break;
}
dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
- data.addr, data.flag);
+ data.addr, data.data);
/* Notify driver for the device which issued the alert */
device_for_each_child(&ara->adapter->dev, &data,
@@ -240,6 +241,31 @@ int i2c_handle_smbus_alert(struct i2c_client *ara)
}
EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
+/**
+ * i2c_propagate_smbus_host_notify - Forward a Host Notify event to the correct
+ * I2C client.
+ * @adapter: the adapter that triggered the Host Notify event
+ * @data: the Host Notify data which contains the payload and address of the
+ * client
+ * Context: Must be able to sleep
+ *
+ * Helper function to be called from an I2C bus driver's interrupt
+ * handler that can sleep. It will call the Host Notify callback of the I2C
+ * device driver if it is found on the adapter.
+ */
+void i2c_propagate_smbus_host_notify(struct i2c_adapter *adapter,
+ unsigned short addr, unsigned int data)
+{
+ struct alert_data alert = {
+ .type = I2C_PROTOCOL_SMBUS_HOST_NOTIFY,
+ .addr = addr,
+ .data = data,
+ };
+
+ device_for_each_child(&adapter->dev, &alert, smbus_do_alert);
+}
+EXPORT_SYMBOL_GPL(i2c_propagate_smbus_host_notify);
+
module_i2c_driver(smbalert_driver);
MODULE_AUTHOR("Jean Delvare <jdelvare@xxxxxxx>");
diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h
index 8f1b086..285efe05 100644
--- a/include/linux/i2c-smbus.h
+++ b/include/linux/i2c-smbus.h
@@ -48,4 +48,12 @@ 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);
+#if defined(CONFIG_I2C_SMBUS) || defined(CONFIG_I2C_SMBUS_MODULE)
+void i2c_propagate_smbus_host_notify(struct i2c_adapter *adapter,
+ unsigned short addr, unsigned int data);
+#else
+static inline void i2c_propagate_smbus_host_notify(struct i2c_adapter *adapter,
+ unsigned short addr, unsigned int data) {}
+#endif /* I2C_SMBUS */
+
#endif /* _LINUX_I2C_SMBUS_H */
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 6764734..81344d3 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -125,6 +125,7 @@ extern s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client,
enum i2c_alert_protocol {
I2C_PROTOCOL_SMBUS_ALERT,
+ I2C_PROTOCOL_SMBUS_HOST_NOTIFY,
};
/**
@@ -181,6 +182,8 @@ struct i2c_driver {
* 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 b0a7dd6..83ec8ae 100644
--- a/include/uapi/linux/i2c.h
+++ b/include/uapi/linux/i2c.h
@@ -101,6 +101,7 @@ struct i2c_msg {
#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)
--
2.4.3
--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
