1 files changed, 260 insertions, 0 deletions

diff --git a/arch/sh/kernel/timers/timer-mtu2.c b/arch/sh/kernel/timers/timer-mtu2.c
new file mode 100644
index 000000000000..73a5ef3c457d
--- /dev/null
+++ b/arch/sh/kernel/timers/timer-mtu2.c
@@ -0,0 +1,260 @@
+/*
+ * 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,
+                                       struct pt_regs *regs)
+{
+        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(regs);
+        write_sequnlock(&xtime_lock);
+
+        return IRQ_HANDLED;
+}
+
+static struct irqaction mtu2_irq = {
+        .name           = "timer",
+        .handler        = mtu2_timer_interrupt,
+        .flags          = SA_INTERRUPT,
+        .mask           = CPU_MASK_NONE,
+};
+
+/*
+ * Hah!  We'll see if this works (switching from usecs to nsecs).
+ */
+static unsigned long mtu2_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_outb(ctrl_inb(MTU2_TSTR) & ~MTU2_TSTR_CST1, MTU2_TSTR);
+        ctrl_outb(MTU2_TCR_CALIB, MTU2_TCR_1);
+        ctrl_outb(ctrl_inb(MTU2_TIER_1) & ~MTU2_TIER_TGIEA, MTU2_TIER_1);
+        ctrl_outw(0, MTU2_TCNT_1);
+
+        rtc_get_time(&ts2);
+
+        do {
+                rtc_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_get_time(&ts2);
+        } while (ts1.tv_nsec == ts2.tv_nsec && ts1.tv_sec == ts2.tv_sec);
+
+        freq = ctrl_inw(MTU2_TCNT_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 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(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,
+        .get_frequency  = mtu2_timer_get_frequency,
+        .get_offset     = mtu2_timer_get_offset,
+};
+
+struct sys_timer mtu2_timer = {
+        .name   = "mtu2",
+        .ops    = &mtu2_timer_ops,
+};