diff options
Diffstat (limited to 'arch/sh/kernel/timers/timer-cmt.c')
| -rw-r--r-- | arch/sh/kernel/timers/timer-cmt.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/arch/sh/kernel/timers/timer-cmt.c b/arch/sh/kernel/timers/timer-cmt.c new file mode 100644 index 000000000000..9eab395cd341 --- /dev/null +++ b/arch/sh/kernel/timers/timer-cmt.c @@ -0,0 +1,256 @@ +/* + * arch/sh/kernel/timers/timer-cmt.c - CMT Timer Support + * + * Copyright (C) 2005 Yoshinori Sato + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + */ + +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/interrupt.h> +#include <linux/spinlock.h> +#include <linux/seqlock.h> +#include <asm/timer.h> +#include <asm/rtc.h> +#include <asm/io.h> +#include <asm/irq.h> +#include <asm/clock.h> + +#if defined(CONFIG_CPU_SUBTYPE_SH7619) +#define CMT_CMSTR 0xf84a0070 +#define CMT_CMCSR_0 0xf84a0072 +#define CMT_CMCNT_0 0xf84a0074 +#define CMT_CMCOR_0 0xf84a0076 +#define CMT_CMCSR_1 0xf84a0078 +#define CMT_CMCNT_1 0xf84a007a +#define CMT_CMCOR_1 0xf84a007c + +#define STBCR3 0xf80a0000 +#define cmt_clock_enable() do { ctrl_outb(ctrl_inb(STBCR3) & ~0x10, STBCR3); } while(0) +#define CMT_CMCSR_INIT 0x0040 +#define CMT_CMCSR_CALIB 0x0000 +#elif defined(CONFIG_CPU_SUBTYPE_SH7206) +#define CMT_CMSTR 0xfffec000 +#define CMT_CMCSR_0 0xfffec002 +#define CMT_CMCNT_0 0xfffec004 +#define CMT_CMCOR_0 0xfffec006 + +#define STBCR4 0xfffe040c +#define cmt_clock_enable() do { ctrl_outb(ctrl_inb(STBCR4) & ~0x04, STBCR4); } while(0) +#define CMT_CMCSR_INIT 0x0040 +#define CMT_CMCSR_CALIB 0x0000 +#else +#error "Unknown CPU SUBTYPE" +#endif + +static DEFINE_SPINLOCK(cmt0_lock); + +static unsigned long cmt_timer_get_offset(void) +{ + int count; + unsigned long flags; + + static unsigned short count_p = 0xffff; /* for the first call after boot */ + static unsigned long jiffies_p = 0; + + /* + * cache volatile jiffies temporarily; we have IRQs turned off. + */ + unsigned long jiffies_t; + + spin_lock_irqsave(&cmt0_lock, flags); + /* timer count may underflow right here */ + count = ctrl_inw(CMT_CMCOR_0); + count -= ctrl_inw(CMT_CMCNT_0); + + jiffies_t = jiffies; + + /* + * avoiding timer inconsistencies (they are rare, but they happen)... + * there is one kind of problem that must be avoided here: + * 1. the timer counter underflows + */ + + if (jiffies_t == jiffies_p) { + if (count > count_p) { + /* the nutcase */ + if (ctrl_inw(CMT_CMCSR_0) & 0x80) { /* Check CMF bit */ + count -= LATCH; + } else { + printk("%s (): hardware timer problem?\n", + __FUNCTION__); + } + } + } else + jiffies_p = jiffies_t; + + count_p = count; + spin_unlock_irqrestore(&cmt0_lock, flags); + + count = ((LATCH-1) - count) * TICK_SIZE; + count = (count + LATCH/2) / LATCH; + + return count; +} + +static irqreturn_t cmt_timer_interrupt(int irq, void *dev_id, + struct pt_regs *regs) +{ + unsigned long timer_status; + + /* Clear CMF bit */ + timer_status = ctrl_inw(CMT_CMCSR_0); + timer_status &= ~0x80; + ctrl_outw(timer_status, CMT_CMCSR_0); + + /* + * Here we are in the timer irq handler. We just have irqs locally + * disabled but we don't know if the timer_bh is running on the other + * CPU. We need to avoid to SMP race with it. NOTE: we don' t need + * the irq version of write_lock because as just said we have irq + * locally disabled. -arca + */ + write_seqlock(&xtime_lock); + handle_timer_tick(regs); + write_sequnlock(&xtime_lock); + + return IRQ_HANDLED; +} + +static struct irqaction cmt_irq = { + .name = "timer", + .handler = cmt_timer_interrupt, + .flags = SA_INTERRUPT, + .mask = CPU_MASK_NONE, +}; + +/* + * Hah! We'll see if this works (switching from usecs to nsecs). + */ +static unsigned long cmt_timer_get_frequency(void) +{ + u32 freq; + struct timespec ts1, ts2; + unsigned long diff_nsec; + unsigned long factor; + + /* Setup the timer: We don't want to generate interrupts, just + * have it count down at its natural rate. + */ + + ctrl_outw(ctrl_inw(CMT_CMSTR) & ~0x01, CMT_CMSTR); + ctrl_outw(CMT_CMCSR_CALIB, CMT_CMCSR_0); + ctrl_outw(0xffff, CMT_CMCOR_0); + ctrl_outw(0xffff, CMT_CMCNT_0); + + rtc_sh_get_time(&ts2); + + do { + rtc_sh_get_time(&ts1); + } while (ts1.tv_nsec == ts2.tv_nsec && ts1.tv_sec == ts2.tv_sec); + + /* actually start the timer */ + ctrl_outw(ctrl_inw(CMT_CMSTR) | 0x01, CMT_CMSTR); + + do { + rtc_sh_get_time(&ts2); + } while (ts1.tv_nsec == ts2.tv_nsec && ts1.tv_sec == ts2.tv_sec); + + freq = 0xffff - ctrl_inw(CMT_CMCNT_0); + if (ts2.tv_nsec < ts1.tv_nsec) { + ts2.tv_nsec += 1000000000; + ts2.tv_sec--; + } + + diff_nsec = (ts2.tv_sec - ts1.tv_sec) * 1000000000 + (ts2.tv_nsec - ts1.tv_nsec); + + /* this should work well if the RTC has a precision of n Hz, where + * n is an integer. I don't think we have to worry about the other + * cases. */ + factor = (1000000000 + diff_nsec/2) / diff_nsec; + + if (factor * diff_nsec > 1100000000 || + factor * diff_nsec < 900000000) + panic("weird RTC (diff_nsec %ld)", diff_nsec); + + return freq * factor; +} + +static void cmt_clk_init(struct clk *clk) +{ + u8 divisor = CMT_CMCSR_INIT & 0x3; + ctrl_inw(CMT_CMCSR_0); + ctrl_outw(CMT_CMCSR_INIT, CMT_CMCSR_0); + clk->parent = clk_get("module_clk"); + clk->rate = clk->parent->rate / (8 << (divisor << 1)); +} + +static void cmt_clk_recalc(struct clk *clk) +{ + u8 divisor = ctrl_inw(CMT_CMCSR_0) & 0x3; + clk->rate = clk->parent->rate / (8 << (divisor << 1)); +} + +static struct clk_ops cmt_clk_ops = { + .init = cmt_clk_init, + .recalc = cmt_clk_recalc, +}; + +static struct clk cmt0_clk = { + .name = "cmt0_clk", + .ops = &cmt_clk_ops, +}; + +static int cmt_timer_start(void) +{ + ctrl_outw(ctrl_inw(CMT_CMSTR) | 0x01, CMT_CMSTR); + return 0; +} + +static int cmt_timer_stop(void) +{ + ctrl_outw(ctrl_inw(CMT_CMSTR) & ~0x01, CMT_CMSTR); + return 0; +} + +static int cmt_timer_init(void) +{ + unsigned long interval; + + cmt_clock_enable(); + + setup_irq(TIMER_IRQ, &cmt_irq); + + cmt0_clk.parent = clk_get("module_clk"); + + cmt_timer_stop(); + + interval = cmt0_clk.parent->rate / 8 / HZ; + printk(KERN_INFO "Interval = %ld\n", interval); + + ctrl_outw(interval, CMT_CMCOR_0); + + clk_register(&cmt0_clk); + clk_enable(&cmt0_clk); + + cmt_timer_start(); + + return 0; +} + +struct sys_timer_ops cmt_timer_ops = { + .init = cmt_timer_init, + .start = cmt_timer_start, + .stop = cmt_timer_stop, + .get_frequency = cmt_timer_get_frequency, + .get_offset = cmt_timer_get_offset, +}; + +struct sys_timer cmt_timer = { + .name = "cmt", + .ops = &cmt_timer_ops, +}; + |