Hi, I faced a problem with DS1337 RTC. I use a pxa255 cpu with 2.6.16 kernel. I tried to make a DS1339 chip (real time clock) working with hwclock. In my config, I selected I2C, DS1337/DS1339 driver, and ehanced RTC support to have it working with /dev/rtc as expected by hwclock. That is to say the following options: CONFIG_RTC=y CONFIG_I2C=y CONFIG_I2C_PXA=y CONFIG_SENSORS_DS1337=y The ioctl() to dev/rtc did not work. While investaigating on that issue, I found 2 problems : - the option "Enhanced Real Time Clock Support" (config RTC) does not provide generic access to a RTC chip via /dev/rtc as I belevied. The access to the chip in driver/char/rtc.c are made with CMOS_READ() and CMOS_WRITE(), defined in Linux/include/asm-arm/mc146818rtc.h. It is a combination of outb_p() and inb_p() : no chance to access my I2C chip that way... So I added ioct() support in /drivers/i2c/chips/ds1337.c. - the driver (/drivers/i2c/chips/ds1337.c) has two problems (I'm not sure it is bugs, but at least on my system it does not work). First, ds1337_detect() reads some values in the chip registers that are assumed to be wrong, but in my chip they do exist (I swear I have a DS1339). I commented out these checks. Then, the part that enables the RTC after first power up in ds1337_init_client() fails to write a status bit in the chip, so we fall into the same reset code (that writes zeros in the RTC regs) after each reboot. I corrected this and that's OK for me. I can post code if it is usefull for someone.
