linux-stable/arch/m68k/sun3x/time.c
Finn Thain b65769fc01 m68k: Fix off-by-one calendar month
This fixes a bug in read_persistent_clock() which causes the system
clock to lag the Real Time Clock by one month. The problem was noticed
on a Mac, but theoretically it must also affect Atari, BVME6000 and Q40.

The tm_mon value in the struct rtc_time passed to mach_hwclk() is
zero-based, and atari_mste_hwclk(), atari_tt_hwclk(), bvme6000_hwclk(),
mac_hwclk() and q40_hwclk() all make this adjustment. Unfortunately,
dn_dummy_hwclk(), mvme147_hwclk(), mvme16x_hwclk(), sun3_hwclk() and
sun3x_hwclk() fail to decrement tm_mon.  Also m68328_hwclk() assumes
a one-based tm_mon.

Bring these platforms into line and fix read_persistent_clock() so it
works correctly on all m68k platforms.

The datasheets for the RTC devices found on the affected platforms
all confirm that the year is stored as a value in the range 0-99 and
the month is stored as a value in the range 1-12. Please refer to the
datasheets for MC146818 (Apollo), DS1643 (MVME), ICM7170 (Sun 3)
and M48T02 (Sun 3x).

Reported-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
2018-05-22 10:31:50 +02:00

105 lines
2.1 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* linux/arch/m68k/sun3x/time.c
*
* Sun3x-specific time handling
*/
#include <linux/types.h>
#include <linux/kd.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/kernel_stat.h>
#include <linux/interrupt.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/machdep.h>
#include <asm/traps.h>
#include <asm/sun3x.h>
#include <asm/sun3ints.h>
#include "time.h"
#define M_CONTROL 0xf8
#define M_SEC 0xf9
#define M_MIN 0xfa
#define M_HOUR 0xfb
#define M_DAY 0xfc
#define M_DATE 0xfd
#define M_MONTH 0xfe
#define M_YEAR 0xff
#define C_WRITE 0x80
#define C_READ 0x40
#define C_SIGN 0x20
#define C_CALIB 0x1f
int sun3x_hwclk(int set, struct rtc_time *t)
{
volatile struct mostek_dt *h =
(struct mostek_dt *)(SUN3X_EEPROM+M_CONTROL);
unsigned long flags;
local_irq_save(flags);
if(set) {
h->csr |= C_WRITE;
h->sec = bin2bcd(t->tm_sec);
h->min = bin2bcd(t->tm_min);
h->hour = bin2bcd(t->tm_hour);
h->wday = bin2bcd(t->tm_wday);
h->mday = bin2bcd(t->tm_mday);
h->month = bin2bcd(t->tm_mon + 1);
h->year = bin2bcd(t->tm_year % 100);
h->csr &= ~C_WRITE;
} else {
h->csr |= C_READ;
t->tm_sec = bcd2bin(h->sec);
t->tm_min = bcd2bin(h->min);
t->tm_hour = bcd2bin(h->hour);
t->tm_wday = bcd2bin(h->wday);
t->tm_mday = bcd2bin(h->mday);
t->tm_mon = bcd2bin(h->month) - 1;
t->tm_year = bcd2bin(h->year);
h->csr &= ~C_READ;
if (t->tm_year < 70)
t->tm_year += 100;
}
local_irq_restore(flags);
return 0;
}
/* Not much we can do here */
u32 sun3x_gettimeoffset(void)
{
return 0L;
}
#if 0
static void sun3x_timer_tick(int irq, void *dev_id, struct pt_regs *regs)
{
void (*vector)(int, void *, struct pt_regs *) = dev_id;
/* Clear the pending interrupt - pulse the enable line low */
disable_irq(5);
enable_irq(5);
vector(irq, NULL, regs);
}
#endif
void __init sun3x_sched_init(irq_handler_t vector)
{
sun3_disable_interrupts();
/* Pulse enable low to get the clock started */
sun3_disable_irq(5);
sun3_enable_irq(5);
sun3_enable_interrupts();
}