diff options
Diffstat (limited to 'Documentation/i2c/i2c-stub')
| -rw-r--r-- | Documentation/i2c/i2c-stub | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/Documentation/i2c/i2c-stub b/Documentation/i2c/i2c-stub index fa4b669c166b..a16924fbd289 100644 --- a/Documentation/i2c/i2c-stub +++ b/Documentation/i2c/i2c-stub @@ -2,9 +2,9 @@ MODULE: i2c-stub DESCRIPTION: -This module is a very simple fake I2C/SMBus driver. It implements five +This module is a very simple fake I2C/SMBus driver. It implements six types of SMBus commands: write quick, (r/w) byte, (r/w) byte data, (r/w) -word data, and (r/w) I2C block data. +word data, (r/w) I2C block data, and (r/w) SMBus block data. 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. @@ -19,6 +19,14 @@ A pointer register with auto-increment is implemented for all byte operations. This allows for continuous byte reads like those supported by EEPROMs, among others. +SMBus block command support is disabled by default, and must be enabled +explicitly by setting the respective bits (0x03000000) in the functionality +module parameter. + +SMBus block commands must be written to configure an SMBus command for +SMBus block operations. Writes can be partial. Block read commands always +return the number of bytes selected with the largest write so far. + The typical use-case is like this: 1. load this module 2. use i2cset (from the i2c-tools project) to pre-load some data @@ -39,15 +47,18 @@ unsigned long functionality: value 0x1f0000 would only enable the quick, byte and byte data commands. +u8 bank_reg[10] +u8 bank_mask[10] +u8 bank_start[10] +u8 bank_end[10]: + Optional bank settings. They tell which bits in which register + select the active bank, as well as the range of banked registers. + CAVEATS: If your target driver polls some byte or word waiting for it to change, the stub could lock it up. Use i2cset to unlock it. -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. - If you spam it hard enough, printk can be lossy. This module really wants something like relayfs. |