Re: [PATCH 1/4] i2c: smbus: add core function handling SMBus host-notify

Pierre Yves MORDRET
2020-05-11T08:26:38Z

Hi all,

Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>

Thanks

On 5/5/20 7:51 AM, Alain Volmat wrote:
> SMBus Host-Notify protocol, from the adapter point of view
> consist of receiving a message from a client, including the
> client address and some other data.
>
> It can be simply handled by creating a new slave device
> and registering a callback performing the parsing of the
> message received from the client.
>
> This commit introduces two new core functions
> * i2c_new_smbus_host_notify_device
> * i2c_free_smbus_host_notify_device
> that take care of registration of the new slave device and
> callback and will call i2c_handle_smbus_host_notify once a
> Host-Notify event is received.
>
> Signed-off-by: Alain Volmat <alain.volmat@st.com>
> ---
> drivers/i2c/i2c-core-smbus.c | 105 +++++++++++++++++++++++++++++++++++
> include/linux/i2c-smbus.h | 2 +
> 2 files changed, 107 insertions(+)
>
> diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
> index b34d2ff06931..0c7e135c73e1 100644
> --- a/drivers/i2c/i2c-core-smbus.c
> +++ b/drivers/i2c/i2c-core-smbus.c
> @@ -708,3 +708,108 @@ int of_i2c_setup_smbus_alert(struct i2c_adapter *adapter)
> }
> EXPORT_SYMBOL_GPL(of_i2c_setup_smbus_alert);
> #endif
> +
> +struct i2c_smbus_host_notify_status {
> + bool notify_start;
> + u8 addr;
> +};
> +
> +static int i2c_smbus_host_notify_cb(struct i2c_client *client,
> + enum i2c_slave_event event, u8 *val)
> +{
> + struct i2c_smbus_host_notify_status *status = client->dev.platform_data;
> + int ret;
> +
> + switch (event) {
> + case I2C_SLAVE_WRITE_REQUESTED:
> + status->notify_start = true;
> + break;
> + case I2C_SLAVE_WRITE_RECEIVED:
> + /* We only retrieve the first byte received (addr)
> + * since there is currently no way to retrieve the data
> + * parameter from the client.
> + */
> + if (!status->notify_start)
> + break;
> + status->addr = *val;
> + status->notify_start = false;
> + break;
> + case I2C_SLAVE_STOP:
> + ret = i2c_handle_smbus_host_notify(client->adapter,
> + status->addr);
> + if (ret < 0) {
> + dev_warn(&client->adapter->dev, "failed to handle host_notify (%d)\n",
> + ret);
> + return ret;
> + }
> + break;
> + default:
> + /* Only handle necessary events */
> + break;
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * i2c_new_smbus_host_notify_device - get a client for SMBus host-notify support
> + * @adapter: the target adapter
> + * Context: can sleep
> + *
> + * Setup handling of the SMBus host-notify protocol on a given I2C bus segment.
> + *
> + * Handling is done by creating a device and its callback and handling data
> + * received via the SMBus host-notify address (0x8)
> + *
> + * This returns the client, which should be ultimately freed using
> + * i2c_free_smbus_host_notify_device(); or an ERRPTR to indicate an error.
> + */
> +struct i2c_client *i2c_new_smbus_host_notify_device(struct i2c_adapter *adapter)
> +{
> + struct i2c_board_info host_notify_board_info = {
> + I2C_BOARD_INFO("smbus_host_notify", 0x08),
> + .flags = I2C_CLIENT_SLAVE,
> + };
> + struct i2c_smbus_host_notify_status *status;
> + struct i2c_client *client;
> + int ret;
> +
> + status = kzalloc(sizeof(struct i2c_smbus_host_notify_status),
> + GFP_KERNEL);
> + if (!status)
> + return ERR_PTR(-ENOMEM);
> +
> + host_notify_board_info.platform_data = status;
> +
> + client = i2c_new_client_device(adapter, &host_notify_board_info);
> + if (IS_ERR(client)) {
> + kfree(status);
> + return client;
> + }
> +
> + ret = i2c_slave_register(client, i2c_smbus_host_notify_cb);
> + if (ret) {
> + i2c_unregister_device(client);
> + kfree(status);
> + return ERR_PTR(ret);
> + }
> +
> + return client;
> +}
> +EXPORT_SYMBOL_GPL(i2c_new_smbus_host_notify_device);
> +
> +/**
> + * i2c_free_smbus_host_notify_device - free the client for SMBus host-notify
> + * support
> + * @client: the client to free
> + * Context: can sleep
> + *
> + * Free the i2c_client allocated via i2c_new_smbus_host_notify_device
> + */
> +void i2c_free_smbus_host_notify_device(struct i2c_client *client)
> +{
> + i2c_slave_unregister(client);
> + kfree(client->dev.platform_data);
> + i2c_unregister_device(client);
> +}
> +EXPORT_SYMBOL_GPL(i2c_free_smbus_host_notify_device);
> diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h
> index 8c5459034f92..926f6d8ae30d 100644
> --- a/include/linux/i2c-smbus.h
> +++ b/include/linux/i2c-smbus.h
> @@ -38,5 +38,7 @@ static inline int of_i2c_setup_smbus_alert(struct i2c_adapter *adap)
> return 0;
> }
> #endif
> +struct i2c_client *i2c_new_smbus_host_notify_device(struct i2c_adapter *adapter);
> +void i2c_free_smbus_host_notify_device(struct i2c_client *client);
>
> #endif /* _LINUX_I2C_SMBUS_H */
>