diff options
| -rw-r--r-- | drivers/acorn/char/i2c.c | 100 |
1 files changed, 68 insertions, 32 deletions
diff --git a/drivers/acorn/char/i2c.c b/drivers/acorn/char/i2c.c index cb662980f90e..e01e4fd5f5d6 100644 --- a/drivers/acorn/char/i2c.c +++ b/drivers/acorn/char/i2c.c @@ -34,9 +34,13 @@ extern int (*set_rtc)(void); static struct i2c_client *rtc_client; static const unsigned char days_in_mon[] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; -static unsigned int rtc_epoch = 1900; #define CMOS_CHECKSUM (63) + +/* + * Acorn machines store the year in the static RAM at + * location 128. + */ #define CMOS_YEAR (64 + 128) static inline int rtc_command(int cmd, void *data) @@ -50,51 +54,89 @@ static inline int rtc_command(int cmd, void *data) } /* + * Update the century + year bytes in the CMOS RAM, ensuring + * that the check byte is correctly adjusted for the change. + */ +static int rtc_update_year(unsigned int new_year) +{ + unsigned char yr[2], chk; + struct mem cmos_year = { CMOS_YEAR, sizeof(yr), yr }; + struct mem cmos_check = { CMOS_CHECKSUM, 1, &chk }; + int ret; + + ret = rtc_command(MEM_READ, &cmos_check); + if (ret) + goto out; + ret = rtc_command(MEM_READ, &cmos_year); + if (ret) + goto out; + + chk -= yr[1] + yr[0]; + + yr[1] = new_year / 100; + yr[0] = new_year % 100; + + chk += yr[1] + yr[0]; + + ret = rtc_command(MEM_WRITE, &cmos_year); + if (ret == 0) + ret = rtc_command(MEM_WRITE, &cmos_check); + out: + return ret; +} + +/* * Read the current RTC time and date, and update xtime. */ static void get_rtc_time(struct rtc_tm *rtctm, unsigned int *year) { unsigned char ctrl, yr[2]; struct mem rtcmem = { CMOS_YEAR, sizeof(yr), yr }; + int real_year, year_offset; /* * Ensure that the RTC is running. */ rtc_command(RTC_GETCTRL, &ctrl); if (ctrl & 0xc0) { - unsigned char new_ctrl; - - new_ctrl = ctrl & ~0xc0; + unsigned char new_ctrl = ctrl & ~0xc0; - printk("RTC: resetting control %02X -> %02X\n", + printk(KERN_WARNING "RTC: resetting control %02x -> %02x\n", ctrl, new_ctrl); rtc_command(RTC_SETCTRL, &new_ctrl); } - /* - * Acorn machines store the year in - * the static RAM at location 192. - */ - if (rtc_command(MEM_READ, &rtcmem)) + if (rtc_command(RTC_GETDATETIME, rtctm) || + rtc_command(MEM_READ, &rtcmem)) return; - if (rtc_command(RTC_GETDATETIME, rtctm)) - return; + real_year = yr[0]; - *year = yr[1] * 100 + yr[0]; + /* + * The RTC year holds the LSB two bits of the current + * year, which should reflect the LSB two bits of the + * CMOS copy of the year. Any difference indicates + * that we have to correct the CMOS version. + */ + year_offset = rtctm->year_off - (real_year & 3); + if (year_offset < 0) + /* + * RTC year wrapped. Adjust it appropriately. + */ + year_offset += 4; + + *year = real_year + year_offset + yr[1] * 100; } static int set_rtc_time(struct rtc_tm *rtctm, unsigned int year) { - unsigned char yr[2], leap, chk; - struct mem cmos_year = { CMOS_YEAR, sizeof(yr), yr }; - struct mem cmos_check = { CMOS_CHECKSUM, 1, &chk }; + unsigned char leap; int ret; leap = (!(year % 4) && (year % 100)) || !(year % 400); - if (rtctm->mon > 12 || rtctm->mday == 0) + if (rtctm->mon > 12 || rtctm->mon == 0 || rtctm->mday == 0) return -EINVAL; if (rtctm->mday > (days_in_mon[rtctm->mon] + (rtctm->mon == 2 && leap))) @@ -103,21 +145,16 @@ static int set_rtc_time(struct rtc_tm *rtctm, unsigned int year) if (rtctm->hours >= 24 || rtctm->mins >= 60 || rtctm->secs >= 60) return -EINVAL; - ret = rtc_command(RTC_SETDATETIME, rtctm); - if (ret == 0) { - rtc_command(MEM_READ, &cmos_check); - rtc_command(MEM_READ, &cmos_year); - - chk -= yr[1] + yr[0]; - - yr[1] = year / 100; - yr[0] = year % 100; + /* + * The RTC's own 2-bit year must reflect the least + * significant two bits of the CMOS year. + */ + rtctm->year_off = (year % 100) & 3; - chk += yr[1] + yr[0]; + ret = rtc_command(RTC_SETDATETIME, rtctm); + if (ret == 0) + ret = rtc_update_year(year); - rtc_command(MEM_WRITE, &cmos_year); - rtc_command(MEM_WRITE, &cmos_check); - } return ret; } @@ -189,13 +226,12 @@ static int rtc_ioctl(struct inode *inode, struct file *file, rtc_raw.hours = rtctm.tm_hour; rtc_raw.mday = rtctm.tm_mday; rtc_raw.mon = rtctm.tm_mon + 1; - rtc_raw.year_off = 2; year = rtctm.tm_year + 1900; return set_rtc_time(&rtc_raw, year); break; case RTC_EPOCH_READ: - return put_user(rtc_epoch, (unsigned long *)arg); + return put_user(1900, (unsigned long *)arg); } return -EINVAL; |