i2c: stub: Add support for banked register ranges

Some chips implement banked register ranges. This allows implementing
more registers than the limited 8-bit address space originally allows.
In order to access a register on these chips, you must first select
the proper bank. Add support for this mechanism to the i2c-stub driver
so that such chips can be emulated. All the bank settings are passed
as module parameters.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 7 insertions, 4 deletions

diff --git a/Documentation/i2c/i2c-stub b/Documentation/i2c/i2c-stub
index a0fe7a04a3bd..a16924fbd289 100644
--- a/Documentation/i2c/i2c-stub
+++ b/Documentation/i2c/i2c-stub
@@ -47,15 +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.