Hallo Sven, On Mon, 30 Nov 2009 22:30:07 +0100, Sven Anders wrote: > I'm trying to code a watchdog driver for the Winbond w83793g chip. I > already coded a watchdog for another Winbond chip before, but for > this I need to access it over the system managment bus (or more > specific the i2c, client address 2E). > > I already coded the detection and initialization routines, but now I > need some help, because I do not know how to use the i2c framework > together with the watchdog framework. > All other drivers I found are using the sysfs framework. This functions > use the to_i2c_client() function to get a pointer to the i2c client. > > I tried to store the i2c client pointer to a global variable, to use > it later in the watchdog functions. > > But when I try to use the "i2c_smbus_read_byte_data()" or > "i2c_smbus_write_byte_data()" functions, I will get a kernel OOPS > (without any hw-sensors driver loaded!). > > What is the best method to get the watchdog framework (i.e. the open, > close, write, read and ioctl functions) to work with the i2c framework? The fact that the device is accessed over I2C/SMBus doesn't change anything to the watchdog interface. It is only an implementation detail for the way the data registers are accessed. > Moreover the w83793g hardware sensors driver may already > accessing the same chip. What is the normal way to deal with this? Do not write a separate driver for the watchdog functionality. Instead, add the functionality to the existing hwmon/w83793.c driver. Otherwise both features will be mutually exclusive. An example of how this can be done is in hwmon/fschmd.c [1] if you want to take a look. This is an I2C/SMBus device driver as well, so your code should be very similar in the end. [1] http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=drivers/hwmon/fschmd.c Hope this helps, -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
