Commit 2a71593d authored by Alain Volmat's avatar Alain Volmat Committed by Wolfram Sang
Browse files

i2c: smbus: add core function handling SMBus host-notify 



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_slave_host_notify_device
  * i2c_free_slave_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: default avatarAlain Volmat <alain.volmat@st.com>
Reviewed-by: default avatarPierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: default avatarWolfram Sang <wsa@kernel.org>
parent e6277308

drivers/i2c/i2c-smbus.c

+107 −0
Original line number Diff line number Diff line
@@ -197,6 +197,113 @@ EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert); 


module_i2c_driver(smbalert_driver);



#if IS_ENABLED(CONFIG_I2C_SLAVE)

#define SMBUS_HOST_NOTIFY_LEN	3

struct i2c_slave_host_notify_status {

	u8 index;

	u8 addr;

};



static int i2c_slave_host_notify_cb(struct i2c_client *client,

				    enum i2c_slave_event event, u8 *val)

{

	struct i2c_slave_host_notify_status *status = client->dev.platform_data;



	switch (event) {

	case I2C_SLAVE_WRITE_RECEIVED:

		/* We only retrieve the first byte received (addr)

		 * since there is currently no support to retrieve the data

		 * parameter from the client.

		 */

		if (status->index == 0)

			status->addr = *val;

		if (status->index < U8_MAX)

			status->index++;

		break;

	case I2C_SLAVE_STOP:

		if (status->index == SMBUS_HOST_NOTIFY_LEN)

			i2c_handle_smbus_host_notify(client->adapter,

						     status->addr);

		fallthrough;

	case I2C_SLAVE_WRITE_REQUESTED:

		status->index = 0;

		break;

	case I2C_SLAVE_READ_REQUESTED:

	case I2C_SLAVE_READ_PROCESSED:

		*val = 0xff;

		break;

	}



	return 0;

}



/**

 * i2c_new_slave_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_slave_host_notify_device(); or an ERRPTR to indicate an error.

 */

struct i2c_client *i2c_new_slave_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_slave_host_notify_status *status;

	struct i2c_client *client;

	int ret;



	status = kzalloc(sizeof(struct i2c_slave_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_slave_host_notify_cb);

	if (ret) {

		i2c_unregister_device(client);

		kfree(status);

		return ERR_PTR(ret);

	}



	return client;

}

EXPORT_SYMBOL_GPL(i2c_new_slave_host_notify_device);



/**

 * i2c_free_slave_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_slave_host_notify_device

 */

void i2c_free_slave_host_notify_device(struct i2c_client *client)

{

	if (IS_ERR_OR_NULL(client))

		return;



	i2c_slave_unregister(client);

	kfree(client->dev.platform_data);

	i2c_unregister_device(client);

}

EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device);

#endif



/*

 * SPD is not part of SMBus but we include it here for convenience as the

 * target systems are the same.

include/linux/i2c-smbus.h

+12 −0
Original line number Diff line number Diff line
@@ -38,6 +38,18 @@ static inline int of_i2c_setup_smbus_alert(struct i2c_adapter *adap) 
	return 0;

}

#endif

#if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_I2C_SLAVE)

struct i2c_client *i2c_new_slave_host_notify_device(struct i2c_adapter *adapter);

void i2c_free_slave_host_notify_device(struct i2c_client *client);

#else

static inline struct i2c_client *i2c_new_slave_host_notify_device(struct i2c_adapter *adapter)

{

	return ERR_PTR(-ENOSYS);

}

static inline void i2c_free_slave_host_notify_device(struct i2c_client *client)

{

}

#endif



#if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_DMI)

void i2c_register_spd(struct i2c_adapter *adap);

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