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/*
* arch/sh/kernel/timers/timer-mtu2.c - MTU2 Timer Support
*
* Copyright (C) 2005 Paul Mundt
*
* Based off of arch/sh/kernel/timers/timer-tmu.c
*
* 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/io.h>
#include <asm/irq.h>
#include <asm/clock.h>
/*
* We use channel 1 for our lowly system timer. Channel 2 would be the other
* likely candidate, but we leave it alone as it has higher divisors that
* would be of more use to other more interesting applications.
*
* TODO: Presently we only implement a 16-bit single-channel system timer.
* However, we can implement channel cascade if we go the overflow route and
* get away with using 2 MTU2 channels as a 32-bit timer.
*/
static DEFINE_SPINLOCK(mtu2_lock);
#define MTU2_TSTR 0xfffe4280
#define MTU2_TCR_1 0xfffe4380
#define MTU2_TMDR_1 0xfffe4381
#define MTU2_TIOR_1 0xfffe4382
#define MTU2_TIER_1 0xfffe4384
#define MTU2_TSR_1 0xfffe4385
#define MTU2_TCNT_1 0xfffe4386 /* 16-bit counter */
#define MTU2_TGRA_1 0xfffe438a
#define STBCR3 0xfffe0408
#define MTU2_TSTR_CST1 (1 << 1) /* Counter Start 1 */
#define MTU2_TSR_TGFA (1 << 0) /* GRA compare match */
#define MTU2_TIER_TGIEA (1 << 0) /* GRA compare match interrupt enable */
#define MTU2_TCR_INIT 0x22
#define MTU2_TCR_CALIB 0x00
static unsigned long mtu2_timer_get_offset(void)
{
int count;
unsigned long flags;
static int count_p = 0x7fff; /* 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(&mtu2_lock, flags);
/* timer count may underflow right here */
count = ctrl_inw(MTU2_TCNT_1); /* read the latched count */
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) {
if (ctrl_inb(MTU2_TSR_1) & MTU2_TSR_TGFA) {
count -= LATCH;
} else {
printk("%s (): hardware timer problem?\n",
__FUNCTION__);
}
}
} else
jiffies_p = jiffies_t;
count_p = count;
spin_unlock_irqrestore(&mtu2_lock, flags);
count = ((LATCH-1) - count) * TICK_SIZE;
count = (count + LATCH/2) / LATCH;
return count;
}
static irqreturn_t mtu2_timer_interrupt(int irq, void *dev_id)
{
unsigned long timer_status;
/* Clear TGFA bit */
timer_status = ctrl_inb(MTU2_TSR_1);
timer_status &= ~MTU2_TSR_TGFA;
ctrl_outb(timer_status, MTU2_TSR_1);
/* Do timer tick */
write_seqlock(&xtime_lock);
handle_timer_tick();
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}
static struct irqaction mtu2_irq = {
.name = "timer",
.handler = mtu2_timer_interrupt,
.flags = IRQF_DISABLED,
.mask = CPU_MASK_NONE,
};
static unsigned int divisors[] = { 1, 4, 16, 64, 1, 1, 256 };
static void mtu2_clk_init(struct clk *clk)
{
u8 idx = MTU2_TCR_INIT & 0x7;
clk->rate = clk->parent->rate / divisors[idx];
/* Start TCNT counting */
ctrl_outb(ctrl_inb(MTU2_TSTR) | MTU2_TSTR_CST1, MTU2_TSTR);
}
static void mtu2_clk_recalc(struct clk *clk)
{
u8 idx = ctrl_inb(MTU2_TCR_1) & 0x7;
clk->rate = clk->parent->rate / divisors[idx];
}
static struct clk_ops mtu2_clk_ops = {
.init = mtu2_clk_init,
.recalc = mtu2_clk_recalc,
};
static struct clk mtu2_clk1 = {
.name = "mtu2_clk1",
.ops = &mtu2_clk_ops,
};
static int mtu2_timer_start(void)
{
ctrl_outb(ctrl_inb(MTU2_TSTR) | MTU2_TSTR_CST1, MTU2_TSTR);
return 0;
}
static int mtu2_timer_stop(void)
{
ctrl_outb(ctrl_inb(MTU2_TSTR) & ~MTU2_TSTR_CST1, MTU2_TSTR);
return 0;
}
static int mtu2_timer_init(void)
{
u8 tmp;
unsigned long interval;
setup_irq(CONFIG_SH_TIMER_IRQ, &mtu2_irq);
mtu2_clk1.parent = clk_get("module_clk");
ctrl_outb(ctrl_inb(STBCR3) & (~0x20), STBCR3);
/* Normal operation */
ctrl_outb(0, MTU2_TMDR_1);
ctrl_outb(MTU2_TCR_INIT, MTU2_TCR_1);
ctrl_outb(0x01, MTU2_TIOR_1);
/* Enable underflow interrupt */
ctrl_outb(ctrl_inb(MTU2_TIER_1) | MTU2_TIER_TGIEA, MTU2_TIER_1);
interval = CONFIG_SH_PCLK_FREQ / 16 / HZ;
printk(KERN_INFO "Interval = %ld\n", interval);
ctrl_outw(interval, MTU2_TGRA_1);
ctrl_outw(0, MTU2_TCNT_1);
clk_register(&mtu2_clk1);
clk_enable(&mtu2_clk1);
return 0;
}
struct sys_timer_ops mtu2_timer_ops = {
.init = mtu2_timer_init,
.start = mtu2_timer_start,
.stop = mtu2_timer_stop,
#ifndef CONFIG_GENERIC_TIME
.get_offset = mtu2_timer_get_offset,
#endif
};
struct sys_timer mtu2_timer = {
.name = "mtu2",
.ops = &mtu2_timer_ops,
};
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