Matthieu TORRES wrote: > > - 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. > I remember having fixed that the same way some time ago - but people told me that I shouldn't add that code to ds1337.c and to look for a "generic way" instead. As I haven't found a better way yet, I decided to write some glue code (drivers/char/ds1337glue.c) till the issue can be resolved. http://www.kernel.org/git/?p=linux/kernel/git/mburian/linux-2.6-ep93xx.git;a=blob;h=c7d168b7ea488676106a363311dc6119e61519a2;hb=e16e2f3f0a126eccf47d4d338b3b1a9281b7cd87;f=drivers/char/ds1337glue.c I doubt that this will be acceptable for mainline, so I'm still waiting for somebody (Jean?) to show me the "one true way" to get /dev/rtc access for that chip. > - 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. I've already sent a patch that should fix this in February :( http://lists.lm-sensors.org/pipermail/lm-sensors/2006-February/015369.html I'm sending a "re-diffed against 2.6.17" version of that patch that, please review and test. To Matthieu: If your fix looks completely different, is better, ... or you'd just like to discuss it, please show us your version. I can live with whatever i2c folks here prefer, as long as it fixes the problem. This patch no longer overwrites the the complete RTC in case it detects inconsistencies - instead it does just what's absolutely necessary to enable userspace to fix the problem. --- linux-2.6.17.old/drivers/i2c/chips/ds1337.c 2006-06-18 03:49:35.000000000 +0200 +++ linux-2.6.17/drivers/i2c/chips/ds1337.c 2006-06-29 10:49:48.000000000 +0200 @@ -337,38 +337,36 @@ exit: static void ds1337_init_client(struct i2c_client *client) { + s32 val; u8 status, control; /* On some boards, the RTC isn't configured by boot firmware. * Handle that case by starting/configuring the RTC now. */ - status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS); control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL); - - if ((status & 0x80) || (control & 0x80)) { + if (control & 0x80) { /* RTC not running */ - u8 buf[16]; - struct i2c_msg msg[1]; - dev_dbg(&client->dev, "%s: RTC not running!\n", __FUNCTION__); + /* reset EOSC to start RTC */ + i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, + control & 0x7f); + } - /* Initialize all, including STATUS and CONTROL to zero */ - memset(buf, 0, sizeof(buf)); - msg[0].addr = client->addr; - msg[0].flags = 0; - msg[0].len = sizeof(buf); - msg[0].buf = &buf[0]; - - i2c_transfer(client->adapter, msg, 1); - } else { - /* Running: ensure that device is set in 24-hour mode */ - s32 val; - - val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR); - if ((val >= 0) && (val & (1 << 6))) - i2c_smbus_write_byte_data(client, DS1337_REG_HOUR, - val & 0x3f); + /* Check if the oscillator was stopped due to power failure, ... */ + status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS); + if (status & 0x80) { + dev_dbg(&client->dev, "%s: oscillator was stopped, RTC data" + " unreliable!\n", __FUNCTION__); + /* reset OSF */ + i2c_smbus_write_byte_data(client, DS1337_REG_STATUS, + status & 0x7f); } + + /* Ensure that device is set in 24-hour mode */ + val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR); + if ((val >= 0) && (val & (1 << 6))) + i2c_smbus_write_byte_data(client, DS1337_REG_HOUR, + val & 0x3f); } static int ds1337_detach_client(struct i2c_client *client)
