diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/i2c/i2c-core.c | 133 |
1 files changed, 124 insertions, 9 deletions
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 3695a4a1ab7..527d51319f3 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -945,10 +945,39 @@ module_exit(i2c_exit); * ---------------------------------------------------- */ +/** + * i2c_transfer - execute a single or combined I2C message + * @adap: Handle to I2C bus + * @msgs: One or more messages to execute before STOP is issued to + * terminate the operation; each message begins with a START. + * @num: Number of messages to be executed. + * + * Returns negative errno, else the number of messages executed. + * + * Note that there is no requirement that each message be sent to + * the same slave address, although that is the most common model. + */ int i2c_transfer(struct i2c_adapter * adap, struct i2c_msg *msgs, int num) { int ret; + /* REVISIT the fault reporting model here is weak: + * + * - When we get an error after receiving N bytes from a slave, + * there is no way to report "N". + * + * - When we get a NAK after transmitting N bytes to a slave, + * there is no way to report "N" ... or to let the master + * continue executing the rest of this combined message, if + * that's the appropriate response. + * + * - When for example "num" is two and we successfully complete + * the first message but get an error part way through the + * second, it's unclear whether that should be reported as + * one (discarding status on the second message) or errno + * (discarding status on the first one). + */ + if (adap->algo->master_xfer) { #ifdef DEBUG for (ret = 0; ret < num; ret++) { @@ -979,6 +1008,14 @@ int i2c_transfer(struct i2c_adapter * adap, struct i2c_msg *msgs, int num) } EXPORT_SYMBOL(i2c_transfer); +/** + * i2c_master_send - issue a single I2C message in master transmit mode + * @client: Handle to slave device + * @buf: Data that will be written to the slave + * @count: How many bytes to write + * + * Returns negative errno, or else the number of bytes written. + */ int i2c_master_send(struct i2c_client *client,const char *buf ,int count) { int ret; @@ -998,6 +1035,14 @@ int i2c_master_send(struct i2c_client *client,const char *buf ,int count) } EXPORT_SYMBOL(i2c_master_send); +/** + * i2c_master_recv - issue a single I2C message in master receive mode + * @client: Handle to slave device + * @buf: Where to store data read from slave + * @count: How many bytes to read + * + * Returns negative errno, or else the number of bytes read. + */ int i2c_master_recv(struct i2c_client *client, char *buf ,int count) { struct i2c_adapter *adap=client->adapter; @@ -1303,6 +1348,13 @@ static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg) return 0; } +/** + * i2c_smbus_read_byte - SMBus "receive byte" protocol + * @client: Handle to slave device + * + * This executes the SMBus "receive byte" protocol, returning negative errno + * else the byte received from the device. + */ s32 i2c_smbus_read_byte(struct i2c_client *client) { union i2c_smbus_data data; @@ -1315,6 +1367,14 @@ s32 i2c_smbus_read_byte(struct i2c_client *client) } EXPORT_SYMBOL(i2c_smbus_read_byte); +/** + * i2c_smbus_write_byte - SMBus "send byte" protocol + * @client: Handle to slave device + * @value: Byte to be sent + * + * This executes the SMBus "send byte" protocol, returning negative errno + * else zero on success. + */ s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value) { return i2c_smbus_xfer(client->adapter,client->addr,client->flags, @@ -1322,6 +1382,14 @@ s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value) } EXPORT_SYMBOL(i2c_smbus_write_byte); +/** + * i2c_smbus_read_byte_data - SMBus "read byte" protocol + * @client: Handle to slave device + * @command: Byte interpreted by slave + * + * This executes the SMBus "read byte" protocol, returning negative errno + * else a data byte received from the device. + */ s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command) { union i2c_smbus_data data; @@ -1334,6 +1402,15 @@ s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command) } EXPORT_SYMBOL(i2c_smbus_read_byte_data); +/** + * i2c_smbus_write_byte_data - SMBus "write byte" protocol + * @client: Handle to slave device + * @command: Byte interpreted by slave + * @value: Byte being written + * + * This executes the SMBus "write byte" protocol, returning negative errno + * else zero on success. + */ s32 i2c_smbus_write_byte_data(struct i2c_client *client, u8 command, u8 value) { union i2c_smbus_data data; @@ -1344,6 +1421,14 @@ s32 i2c_smbus_write_byte_data(struct i2c_client *client, u8 command, u8 value) } EXPORT_SYMBOL(i2c_smbus_write_byte_data); +/** + * i2c_smbus_read_word_data - SMBus "read word" protocol + * @client: Handle to slave device + * @command: Byte interpreted by slave + * + * This executes the SMBus "read word" protocol, returning negative errno + * else a 16-bit unsigned "word" received from the device. + */ s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command) { union i2c_smbus_data data; @@ -1356,6 +1441,15 @@ s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command) } EXPORT_SYMBOL(i2c_smbus_read_word_data); +/** + * i2c_smbus_write_word_data - SMBus "write word" protocol + * @client: Handle to slave device + * @command: Byte interpreted by slave + * @value: 16-bit "word" being written + * + * This executes the SMBus "write word" protocol, returning negative errno + * else zero on success. + */ s32 i2c_smbus_write_word_data(struct i2c_client *client, u8 command, u16 value) { union i2c_smbus_data data; @@ -1367,15 +1461,14 @@ s32 i2c_smbus_write_word_data(struct i2c_client *client, u8 command, u16 value) EXPORT_SYMBOL(i2c_smbus_write_word_data); /** - * i2c_smbus_read_block_data - SMBus block read request + * i2c_smbus_read_block_data - SMBus "block read" protocol * @client: Handle to slave device - * @command: Command byte issued to let the slave know what data should - * be returned + * @command: Byte interpreted by slave * @values: Byte array into which data will be read; big enough to hold * the data returned by the slave. SMBus allows at most 32 bytes. * - * Returns the number of bytes read in the slave's response, else a - * negative number to indicate some kind of error. + * This executes the SMBus "block read" protocol, returning negative errno + * else the number of data bytes in the slave's response. * * Note that using this function requires that the client's adapter support * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers @@ -1399,6 +1492,16 @@ s32 i2c_smbus_read_block_data(struct i2c_client *client, u8 command, } EXPORT_SYMBOL(i2c_smbus_read_block_data); +/** + * i2c_smbus_write_block_data - SMBus "block write" protocol + * @client: Handle to slave device + * @command: Byte interpreted by slave + * @length: Size of data block; SMBus allows at most 32 bytes + * @values: Byte array which will be written. + * + * This executes the SMBus "block write" protocol, returning negative errno + * else zero on success. + */ s32 i2c_smbus_write_block_data(struct i2c_client *client, u8 command, u8 length, const u8 *values) { @@ -1615,9 +1718,21 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr, return 0; } - +/** + * i2c_smbus_xfer - execute SMBus protocol operations + * @adapter: Handle to I2C bus + * @addr: Address of SMBus slave on that bus + * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC) + * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE + * @command: Byte interpreted by slave, for protocols which use such bytes + * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL + * @data: Data to be read or written + * + * This executes an SMBus protocol operation, and returns a negative + * errno code else zero on success. + */ s32 i2c_smbus_xfer(struct i2c_adapter * adapter, u16 addr, unsigned short flags, - char read_write, u8 command, int size, + char read_write, u8 command, int protocol, union i2c_smbus_data * data) { s32 res; @@ -1627,11 +1742,11 @@ s32 i2c_smbus_xfer(struct i2c_adapter * adapter, u16 addr, unsigned short flags, if (adapter->algo->smbus_xfer) { mutex_lock(&adapter->bus_lock); res = adapter->algo->smbus_xfer(adapter,addr,flags,read_write, - command,size,data); + command, protocol, data); mutex_unlock(&adapter->bus_lock); } else res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write, - command,size,data); + command, protocol, data); return res; } |