Re: [PATCH 1/2] i2c: add SMBus Host Notify support

Jean Delvare
2015-06-29T13:00:35Z

Hi Benjamin,

On Tue, 23 Jun 2015 14:58:18 -0400, Benjamin Tissoires wrote:
> SMBus Host Notify allows a slave device to act as a master on a bus to
> notify the host of an interrupt. The functionality is directly implemented
> in the firmware so we just export a toggle function and rely on the
> adapter to actually support this.

Why does it need to be toggled? I mean, if the controller supports it,
why don't we just enable the feature all the time?

> Signed-off-by: Benjamin Tissoires <benjamin.tissoires-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
> Documentation/i2c/smbus-protocol | 4 ++++
> drivers/i2c/i2c-core.c | 26 ++++++++++++++++++++++++++
> include/linux/i2c.h | 8 ++++++++
> include/uapi/linux/i2c.h | 1 +
> 4 files changed, 39 insertions(+)
>
> diff --git a/Documentation/i2c/smbus-protocol b/Documentation/i2c/smbus-protocol
> index 6012b12..af4e4b9 100644
> --- a/Documentation/i2c/smbus-protocol
> +++ b/Documentation/i2c/smbus-protocol
> @@ -199,6 +199,10 @@ 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 call
> +i2c_smbus_toggle_host_notify() to enable SMBUS Host Notify on the adapter
> +and implement the optional alert() callback.
> +
>
> Packet Error Checking (PEC)
> ===========================
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index 987c124..eaaf5b0 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -2959,6 +2959,32 @@ int i2c_slave_unregister(struct i2c_client *client)
> EXPORT_SYMBOL_GPL(i2c_slave_unregister);
> #endif
>
> +int i2c_smbus_toggle_host_notify(struct i2c_client *client, bool state)
> +{
> + int ret;
> +
> + if (!client)
> + return -EINVAL;
> +
> + if (!(client->flags & I2C_CLIENT_TEN)) {
> + /* Enforce stricter address checking */
> + ret = i2c_check_addr_validity(client->addr);
> + if (ret)
> + return ret;
> + }
> +
> + if (!client->adapter->algo->toggle_smbus_host_notify)
> + return -EOPNOTSUPP;
> +
> + i2c_lock_adapter(client->adapter);
> + ret = client->adapter->algo->toggle_smbus_host_notify(client->adapter,
> + state);
> + i2c_unlock_adapter(client->adapter);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(i2c_smbus_toggle_host_notify);
> +

As this is an SMBus feature, can't it go to drivers/i2c/i2c-smbus.c?

> MODULE_AUTHOR("Simon G. Vogl <simon-nD9nYVNVf00W+b/DJNNodF6hYfS7NtTn@public.gmane.org>");
> MODULE_DESCRIPTION("I2C-Bus main module");
> MODULE_LICENSE("GPL");
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index e83a738..7ffc970 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -177,6 +177,8 @@ 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-bits payload data reported by the external device.

16-bit (no s)

> */
> void (*alert)(struct i2c_client *, unsigned int data);
>
> @@ -270,6 +272,9 @@ static inline int i2c_slave_event(struct i2c_client *client,
> }
> #endif
>
> +

No double blank lines in source code please.

> +extern int i2c_smbus_toggle_host_notify(struct i2c_client *client, bool state);
> +
> /**
> * struct i2c_board_info - template for device creation
> * @type: chip type, to initialize i2c_client.name
> @@ -378,6 +383,8 @@ i2c_register_board_info(int busnum, struct i2c_board_info const *info,
> * from the I2C_FUNC_* flags.
> * @reg_slave: Register given client to I2C slave mode of this adapter
> * @unreg_slave: Unregister given client from I2C slave mode of this adapter
> + * @toggle_smbus_host_notify: toggle the SMBus Host Notify support of this
> + * adapter.
> *
> * The following structs are for those who like to implement new bus drivers:
> * i2c_algorithm is the interface to a class of hardware solutions which can
> @@ -408,6 +415,7 @@ struct i2c_algorithm {
> int (*reg_slave)(struct i2c_client *client);
> int (*unreg_slave)(struct i2c_client *client);
> #endif
> + int (*toggle_smbus_host_notify)(struct i2c_adapter *adap, bool state);

Please put it after u32 (*functionality), so that the field offsets do
not depend on configuration options.

> };
>
> /**
> diff --git a/include/uapi/linux/i2c.h b/include/uapi/linux/i2c.h
> index 0e949cb..c72708e 100644
> --- a/include/uapi/linux/i2c.h
> +++ b/include/uapi/linux/i2c.h
> @@ -100,6 +100,7 @@ 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)

--
Jean Delvare
SUSE L3 Support