linux/arch/m68k/mvme147/config.c
Finn Thain 7529b90d05 m68k: mvme147: Handle timer counter overflow
Reading the timer counter races with timer overflow (and the
corresponding interrupt). This is resolved by reading the overflow
register and taking this value into account. The interrupt handler
must clear the overflow register when it eventually executes.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
2019-03-25 10:22:24 +01:00

190 lines
4.5 KiB
C

/*
* arch/m68k/mvme147/config.c
*
* Copyright (C) 1996 Dave Frascone [chaos@mindspring.com]
* Cloned from Richard Hirst [richard@sleepie.demon.co.uk]
*
* Based on:
*
* Copyright (C) 1993 Hamish Macdonald
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file README.legal in the main directory of this archive
* for more details.
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/tty.h>
#include <linux/clocksource.h>
#include <linux/console.h>
#include <linux/linkage.h>
#include <linux/init.h>
#include <linux/major.h>
#include <linux/genhd.h>
#include <linux/rtc.h>
#include <linux/interrupt.h>
#include <asm/bootinfo.h>
#include <asm/bootinfo-vme.h>
#include <asm/byteorder.h>
#include <asm/pgtable.h>
#include <asm/setup.h>
#include <asm/irq.h>
#include <asm/traps.h>
#include <asm/machdep.h>
#include <asm/mvme147hw.h>
static void mvme147_get_model(char *model);
extern void mvme147_sched_init(irq_handler_t handler);
extern int mvme147_hwclk (int, struct rtc_time *);
extern void mvme147_reset (void);
static int bcd2int (unsigned char b);
int __init mvme147_parse_bootinfo(const struct bi_record *bi)
{
uint16_t tag = be16_to_cpu(bi->tag);
if (tag == BI_VME_TYPE || tag == BI_VME_BRDINFO)
return 0;
else
return 1;
}
void mvme147_reset(void)
{
pr_info("\r\n\nCalled mvme147_reset\r\n");
m147_pcc->watchdog = 0x0a; /* Clear timer */
m147_pcc->watchdog = 0xa5; /* Enable watchdog - 100ms to reset */
while (1)
;
}
static void mvme147_get_model(char *model)
{
sprintf(model, "Motorola MVME147");
}
/*
* This function is called during kernel startup to initialize
* the mvme147 IRQ handling routines.
*/
void __init mvme147_init_IRQ(void)
{
m68k_setup_user_interrupt(VEC_USER, 192);
}
void __init config_mvme147(void)
{
mach_max_dma_address = 0x01000000;
mach_sched_init = mvme147_sched_init;
mach_init_IRQ = mvme147_init_IRQ;
mach_hwclk = mvme147_hwclk;
mach_reset = mvme147_reset;
mach_get_model = mvme147_get_model;
/* Board type is only set by newer versions of vmelilo/tftplilo */
if (!vme_brdtype)
vme_brdtype = VME_TYPE_MVME147;
}
static u64 mvme147_read_clk(struct clocksource *cs);
static struct clocksource mvme147_clk = {
.name = "pcc",
.rating = 250,
.read = mvme147_read_clk,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static u32 clk_total;
#define PCC_TIMER_CLOCK_FREQ 160000
#define PCC_TIMER_CYCLES (PCC_TIMER_CLOCK_FREQ / HZ)
#define PCC_TIMER_PRELOAD (0x10000 - PCC_TIMER_CYCLES)
/* Using pcc tick timer 1 */
static irqreturn_t mvme147_timer_int (int irq, void *dev_id)
{
irq_handler_t timer_routine = dev_id;
unsigned long flags;
local_irq_save(flags);
m147_pcc->t1_int_cntrl = PCC_TIMER_INT_CLR;
m147_pcc->t1_cntrl = PCC_TIMER_CLR_OVF;
clk_total += PCC_TIMER_CYCLES;
timer_routine(0, NULL);
local_irq_restore(flags);
return IRQ_HANDLED;
}
void mvme147_sched_init (irq_handler_t timer_routine)
{
if (request_irq(PCC_IRQ_TIMER1, mvme147_timer_int, IRQF_TIMER,
"timer 1", timer_routine))
pr_err("Couldn't register timer interrupt\n");
/* Init the clock with a value */
/* The clock counter increments until 0xFFFF then reloads */
m147_pcc->t1_preload = PCC_TIMER_PRELOAD;
m147_pcc->t1_cntrl = 0x0; /* clear timer */
m147_pcc->t1_cntrl = 0x3; /* start timer */
m147_pcc->t1_int_cntrl = PCC_TIMER_INT_CLR; /* clear pending ints */
m147_pcc->t1_int_cntrl = PCC_INT_ENAB|PCC_LEVEL_TIMER1;
clocksource_register_hz(&mvme147_clk, PCC_TIMER_CLOCK_FREQ);
}
static u64 mvme147_read_clk(struct clocksource *cs)
{
unsigned long flags;
u8 overflow, tmp;
u16 count;
u32 ticks;
local_irq_save(flags);
tmp = m147_pcc->t1_cntrl >> 4;
count = m147_pcc->t1_count;
overflow = m147_pcc->t1_cntrl >> 4;
if (overflow != tmp)
count = m147_pcc->t1_count;
count -= PCC_TIMER_PRELOAD;
ticks = count + overflow * PCC_TIMER_CYCLES;
ticks += clk_total;
local_irq_restore(flags);
return ticks;
}
static int bcd2int (unsigned char b)
{
return ((b>>4)*10 + (b&15));
}
int mvme147_hwclk(int op, struct rtc_time *t)
{
#warning check me!
if (!op) {
m147_rtc->ctrl = RTC_READ;
t->tm_year = bcd2int (m147_rtc->bcd_year);
t->tm_mon = bcd2int(m147_rtc->bcd_mth) - 1;
t->tm_mday = bcd2int (m147_rtc->bcd_dom);
t->tm_hour = bcd2int (m147_rtc->bcd_hr);
t->tm_min = bcd2int (m147_rtc->bcd_min);
t->tm_sec = bcd2int (m147_rtc->bcd_sec);
m147_rtc->ctrl = 0;
if (t->tm_year < 70)
t->tm_year += 100;
}
return 0;
}