diff options
Diffstat (limited to 'Documentation/i2c')
-rw-r--r-- | Documentation/i2c/busses/i2c-i801 | 3 | ||||
-rw-r--r-- | Documentation/i2c/chips/pcf8574 | 8 | ||||
-rw-r--r-- | Documentation/i2c/dev-interface | 11 | ||||
-rw-r--r-- | Documentation/i2c/i2c-stub | 18 |
4 files changed, 21 insertions, 19 deletions
diff --git a/Documentation/i2c/busses/i2c-i801 b/Documentation/i2c/busses/i2c-i801 index fe6406f2f9a..fde4420e3f7 100644 --- a/Documentation/i2c/busses/i2c-i801 +++ b/Documentation/i2c/busses/i2c-i801 @@ -13,7 +13,8 @@ Supported adapters: * Intel 631xESB/632xESB (ESB2) * Intel 82801H (ICH8) * Intel ICH9 - Datasheets: Publicly available at the Intel website + * Intel Tolapai + Datasheets: Publicly available at the Intel website Authors: Frodo Looijaard <frodol@dds.nl>, diff --git a/Documentation/i2c/chips/pcf8574 b/Documentation/i2c/chips/pcf8574 index 2752c8ce316..5c1ad1376b6 100644 --- a/Documentation/i2c/chips/pcf8574 +++ b/Documentation/i2c/chips/pcf8574 @@ -62,8 +62,6 @@ if the corresponding output is set as 1, otherwise the current output value, that is to say 0. The write file is read/write. Writing a value outputs it on the I/O -port. Reading returns the last written value. - -On module initialization the chip is configured as eight inputs (all -outputs to 1), so you can connect any circuit to the PCF8574(A) without -being afraid of short-circuit. +port. Reading returns the last written value. As it is not possible +to read this value from the chip, you need to write at least once to +this file before you can read back from it. diff --git a/Documentation/i2c/dev-interface b/Documentation/i2c/dev-interface index b849ad63658..9dd79123ddd 100644 --- a/Documentation/i2c/dev-interface +++ b/Documentation/i2c/dev-interface @@ -90,12 +90,15 @@ ioctl(file,I2C_SLAVE,long addr) ioctl(file,I2C_TENBIT,long select) Selects ten bit addresses if select not equals 0, selects normal 7 bit - addresses if select equals 0. Default 0. + addresses if select equals 0. Default 0. This request is only valid + if the adapter has I2C_FUNC_10BIT_ADDR. ioctl(file,I2C_PEC,long select) Selects SMBus PEC (packet error checking) generation and verification if select not equals 0, disables if select equals 0. Default 0. - Used only for SMBus transactions. + Used only for SMBus transactions. This request only has an effect if the + the adapter has I2C_FUNC_SMBUS_PEC; it is still safe if not, it just + doesn't have any effect. ioctl(file,I2C_FUNCS,unsigned long *funcs) Gets the adapter functionality and puts it in *funcs. @@ -103,8 +106,10 @@ ioctl(file,I2C_FUNCS,unsigned long *funcs) ioctl(file,I2C_RDWR,struct i2c_rdwr_ioctl_data *msgset) Do combined read/write transaction without stop in between. - The argument is a pointer to a struct i2c_rdwr_ioctl_data { + Only valid if the adapter has I2C_FUNC_I2C. The argument is + a pointer to a + struct i2c_rdwr_ioctl_data { struct i2c_msg *msgs; /* ptr to array of simple messages */ int nmsgs; /* number of messages to exchange */ } diff --git a/Documentation/i2c/i2c-stub b/Documentation/i2c/i2c-stub index 9cc081e6976..89e69ad3436 100644 --- a/Documentation/i2c/i2c-stub +++ b/Documentation/i2c/i2c-stub @@ -6,13 +6,14 @@ This module is a very simple fake I2C/SMBus driver. It implements four types of SMBus commands: write quick, (r/w) byte, (r/w) byte data, and (r/w) word data. -You need to provide a chip address as a module parameter when loading -this driver, which will then only react to SMBus commands to this address. +You need to provide chip addresses as a module parameter when loading this +driver, which will then only react to SMBus commands to these addresses. No hardware is needed nor associated with this module. It will accept write -quick commands to one address; it will respond to the other commands (also -to one address) by reading from or writing to an array in memory. It will -also spam the kernel logs for every command it handles. +quick commands to the specified addresses; it will respond to the other +commands (also to the specified addresses) by reading from or writing to +arrays in memory. It will also spam the kernel logs for every command it +handles. A pointer register with auto-increment is implemented for all byte operations. This allows for continuous byte reads like those supported by @@ -26,8 +27,8 @@ The typical use-case is like this: PARAMETERS: -int chip_addr: - The SMBus address to emulate a chip at. +int chip_addr[10]: + The SMBus addresses to emulate chips at. CAVEATS: @@ -41,9 +42,6 @@ If the hardware for your driver has banked registers (e.g. Winbond sensors chips) this module will not work well - although it could be extended to support that pretty easily. -Only one chip address is supported - although this module could be -extended to support more. - If you spam it hard enough, printk can be lossy. This module really wants something like relayfs. |