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Diffstat (limited to 'Documentation/i2c/i2c-stub')
-rw-r--r-- | Documentation/i2c/i2c-stub | 53 |
1 files changed, 0 insertions, 53 deletions
diff --git a/Documentation/i2c/i2c-stub b/Documentation/i2c/i2c-stub deleted file mode 100644 index fa4b669c166..00000000000 --- a/Documentation/i2c/i2c-stub +++ /dev/null @@ -1,53 +0,0 @@ -MODULE: i2c-stub - -DESCRIPTION: - -This module is a very simple fake I2C/SMBus driver. It implements five -types of SMBus commands: write quick, (r/w) byte, (r/w) byte data, (r/w) -word data, and (r/w) I2C 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. - -No hardware is needed nor associated with this module. It will accept write -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 -EEPROMs, among others. - -The typical use-case is like this: - 1. load this module - 2. use i2cset (from the i2c-tools project) to pre-load some data - 3. load the target chip driver module - 4. observe its behavior in the kernel log - -There's a script named i2c-stub-from-dump in the i2c-tools package which -can load register values automatically from a chip dump. - -PARAMETERS: - -int chip_addr[10]: - The SMBus addresses to emulate chips at. - -unsigned long functionality: - Functionality override, to disable some commands. See I2C_FUNC_* - constants in <linux/i2c.h> for the suitable values. For example, - value 0x1f0000 would only enable the quick, byte and byte data - commands. - -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. - |