diff options
| -rw-r--r-- | Documentation/i2c/dev-interface | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/Documentation/i2c/dev-interface b/Documentation/i2c/dev-interface index d04e6e4..c8737d5 100644 --- a/Documentation/i2c/dev-interface +++ b/Documentation/i2c/dev-interface @@ -9,8 +9,8 @@ i2c adapters present on your system at a given time. i2cdetect is part of the i2c-tools package. I2C device files are character device files with major device number 89 -and a minor device number corresponding to the number assigned as -explained above. They should be called "i2c-%d" (i2c-0, i2c-1, ..., +and a minor device number corresponding to the number assigned as +explained above. They should be called "i2c-%d" (i2c-0, i2c-1, ..., i2c-10, ...). All 256 minor device numbers are reserved for i2c. @@ -38,7 +38,7 @@ Next thing, open the device file, as follows: int file; int adapter_nr = 2; /* probably dynamically determined */ char filename[20]; - + snprintf(filename, 19, "/dev/i2c-%d", adapter_nr); file = open(filename, O_RDWR); if (file < 0) { @@ -72,7 +72,7 @@ the device supports them. Both are illustrated below. /* res contains the read word */ } - /* Using I2C Write, equivalent of + /* Using I2C Write, equivalent of i2c_smbus_write_word_data(file, reg, 0x6543) */ buf[0] = reg; buf[1] = 0x43; @@ -147,7 +147,7 @@ You can do plain i2c transactions by using read(2) and write(2) calls. You do not need to pass the address byte; instead, set it through ioctl I2C_SLAVE before you try to access the device. -You can do SMBus level transactions (see documentation file smbus-protocol +You can do SMBus level transactions (see documentation file smbus-protocol for details) through the following functions: __s32 i2c_smbus_write_quick(int file, __u8 value); __s32 i2c_smbus_read_byte(int file); @@ -158,7 +158,7 @@ for details) through the following functions: __s32 i2c_smbus_write_word_data(int file, __u8 command, __u16 value); __s32 i2c_smbus_process_call(int file, __u8 command, __u16 value); __s32 i2c_smbus_read_block_data(int file, __u8 command, __u8 *values); - __s32 i2c_smbus_write_block_data(int file, __u8 command, __u8 length, + __s32 i2c_smbus_write_block_data(int file, __u8 command, __u8 length, __u8 *values); All these transactions return -1 on failure; you can read errno to see what happened. The 'write' transactions return 0 on success; the |
