[PATCH] sh: Simple timer framework
Paul Mundt [Tue, 17 Jan 2006 06:14:18 +0000 (22:14 -0800)]
This builds on some of the clock framework code to support a simple system
timer interface.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/sh/kernel/timers/Makefile [new file with mode: 0644]
arch/sh/kernel/timers/timer-tmu.c [new file with mode: 0644]
arch/sh/kernel/timers/timer.c [new file with mode: 0644]
include/asm-sh/timer.h [new file with mode: 0644]

diff --git a/arch/sh/kernel/timers/Makefile b/arch/sh/kernel/timers/Makefile
new file mode 100644 (file)
index 0000000..151a6a3
--- /dev/null
@@ -0,0 +1,8 @@
+#
+# Makefile for the various Linux/SuperH timers
+#
+
+obj-y  := timer.o
+
+obj-$(CONFIG_SH_TMU)           += timer-tmu.o
+
diff --git a/arch/sh/kernel/timers/timer-tmu.c b/arch/sh/kernel/timers/timer-tmu.c
new file mode 100644 (file)
index 0000000..96a64cb
--- /dev/null
@@ -0,0 +1,229 @@
+/*
+ * arch/sh/kernel/timers/timer-tmu.c - TMU Timer Support
+ *
+ *  Copyright (C) 2005  Paul Mundt
+ *
+ * TMU handling code hacked out of arch/sh/kernel/time.c
+ *
+ *  Copyright (C) 1999  Tetsuya Okada & Niibe Yutaka
+ *  Copyright (C) 2000  Philipp Rumpf <prumpf@tux.org>
+ *  Copyright (C) 2002, 2003, 2004  Paul Mundt
+ *  Copyright (C) 2002  M. R. Brown  <mrbrown@linux-sh.org>
+ *
+ * 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>
+
+#define TMU_TOCR_INIT  0x00
+#define TMU0_TCR_INIT  0x0020
+#define TMU_TSTR_INIT  1
+
+#define TMU0_TCR_CALIB 0x0000
+
+static DEFINE_SPINLOCK(tmu0_lock);
+
+static unsigned long tmu_timer_get_offset(void)
+{
+       int count;
+       unsigned long flags;
+
+       static int count_p = 0x7fffffff;    /* 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(&tmu0_lock, flags);
+       /* timer count may underflow right here */
+       count = ctrl_inl(TMU0_TCNT);    /* 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) {
+                       /* the nutcase */
+                       if (ctrl_inw(TMU0_TCR) & 0x100) { /* Check UNF bit */
+                               count -= LATCH;
+                       } else {
+                               printk("%s (): hardware timer problem?\n",
+                                      __FUNCTION__);
+                       }
+               }
+       } else
+               jiffies_p = jiffies_t;
+
+       count_p = count;
+       spin_unlock_irqrestore(&tmu0_lock, flags);
+
+       count = ((LATCH-1) - count) * TICK_SIZE;
+       count = (count + LATCH/2) / LATCH;
+
+       return count;
+}
+
+static irqreturn_t tmu_timer_interrupt(int irq, void *dev_id,
+                                      struct pt_regs *regs)
+{
+       unsigned long timer_status;
+
+       /* Clear UNF bit */
+       timer_status = ctrl_inw(TMU0_TCR);
+       timer_status &= ~0x100;
+       ctrl_outw(timer_status, TMU0_TCR);
+
+       /*
+        * 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 tmu_irq = {
+       .name           = "timer",
+       .handler        = tmu_timer_interrupt,
+       .flags          = SA_INTERRUPT,
+       .mask           = CPU_MASK_NONE,
+};
+
+/*
+ * Hah!  We'll see if this works (switching from usecs to nsecs).
+ */
+static unsigned long tmu_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(0, TMU_TSTR);
+#if !defined(CONFIG_CPU_SUBTYPE_SH7300) && !defined(CONFIG_CPU_SUBTYPE_SH7760)
+       ctrl_outb(TMU_TOCR_INIT, TMU_TOCR);
+#endif
+       ctrl_outw(TMU0_TCR_CALIB, TMU0_TCR);
+       ctrl_outl(0xffffffff, TMU0_TCOR);
+       ctrl_outl(0xffffffff, TMU0_TCNT);
+
+       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_outb(TMU_TSTR_INIT, TMU_TSTR);
+
+       do {
+               rtc_get_time(&ts2);
+       } while (ts1.tv_nsec == ts2.tv_nsec && ts1.tv_sec == ts2.tv_sec);
+
+       freq = 0xffffffff - ctrl_inl(TMU0_TCNT);
+       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 tmu_clk_init(struct clk *clk)
+{
+       u8 divisor = TMU0_TCR_INIT & 0x7;
+       ctrl_outw(TMU0_TCR_INIT, TMU0_TCR);
+       clk->rate = clk->parent->rate / (4 << (divisor << 1));
+}
+
+static void tmu_clk_recalc(struct clk *clk)
+{
+       u8 divisor = ctrl_inw(TMU0_TCR) & 0x7;
+       clk->rate = clk->parent->rate / (4 << (divisor << 1));
+}
+
+static struct clk_ops tmu_clk_ops = {
+       .init           = tmu_clk_init,
+       .recalc         = tmu_clk_recalc,
+};
+
+static struct clk tmu0_clk = {
+       .name           = "tmu0_clk",
+       .ops            = &tmu_clk_ops,
+};
+
+static int tmu_timer_init(void)
+{
+       unsigned long interval;
+
+       setup_irq(TIMER_IRQ, &tmu_irq);
+
+       tmu0_clk.parent = clk_get("module_clk");
+
+       /* Start TMU0 */
+       ctrl_outb(0, TMU_TSTR);
+#if !defined(CONFIG_CPU_SUBTYPE_SH7300) && !defined(CONFIG_CPU_SUBTYPE_SH7760)
+       ctrl_outb(TMU_TOCR_INIT, TMU_TOCR);
+#endif
+
+       clk_register(&tmu0_clk);
+       clk_enable(&tmu0_clk);
+
+       interval = (clk_get_rate(&tmu0_clk) + HZ / 2) / HZ;
+       printk(KERN_INFO "Interval = %ld\n", interval);
+
+       ctrl_outl(interval, TMU0_TCOR);
+       ctrl_outl(interval, TMU0_TCNT);
+
+       ctrl_outb(TMU_TSTR_INIT, TMU_TSTR);
+
+       return 0;
+}
+
+struct sys_timer_ops tmu_timer_ops = {
+       .init           = tmu_timer_init,
+       .get_frequency  = tmu_timer_get_frequency,
+       .get_offset     = tmu_timer_get_offset,
+};
+
+struct sys_timer tmu_timer = {
+       .name   = "tmu",
+       .ops    = &tmu_timer_ops,
+};
+
diff --git a/arch/sh/kernel/timers/timer.c b/arch/sh/kernel/timers/timer.c
new file mode 100644 (file)
index 0000000..dc1f631
--- /dev/null
@@ -0,0 +1,50 @@
+/*
+ * arch/sh/kernel/timers/timer.c - Common timer code
+ *
+ *  Copyright (C) 2005  Paul Mundt
+ *
+ * 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/kernel.h>
+#include <linux/init.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <asm/timer.h>
+
+static struct sys_timer *sys_timers[] __initdata = {
+#ifdef CONFIG_SH_TMU
+       &tmu_timer,
+#endif
+       NULL,
+};
+
+static char timer_override[10] __initdata;
+static int __init timer_setup(char *str)
+{
+       if (str)
+               strlcpy(timer_override, str, sizeof(timer_override));
+       return 1;
+}
+__setup("timer=", timer_setup);
+
+struct sys_timer *get_sys_timer(void)
+{
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(sys_timers); i++) {
+               struct sys_timer *t = sys_timers[i];
+
+               if (unlikely(!t))
+                       break;
+               if (unlikely(timer_override[0]))
+                       if ((strcmp(timer_override, t->name) != 0))
+                               continue;
+               if (likely(t->ops->init() == 0))
+                       return t;
+       }
+
+       return NULL;
+}
+
diff --git a/include/asm-sh/timer.h b/include/asm-sh/timer.h
new file mode 100644 (file)
index 0000000..dd6579c
--- /dev/null
@@ -0,0 +1,42 @@
+#ifndef __ASM_SH_TIMER_H
+#define __ASM_SH_TIMER_H
+
+#include <linux/sysdev.h>
+#include <asm/cpu/timer.h>
+
+struct sys_timer_ops {
+       int (*init)(void);
+       unsigned long (*get_offset)(void);
+       unsigned long (*get_frequency)(void);
+};
+
+struct sys_timer {
+       const char              *name;
+
+       struct sys_device       dev;
+       struct sys_timer_ops    *ops;
+};
+
+#define TICK_SIZE (tick_nsec / 1000)
+
+extern struct sys_timer tmu_timer;
+extern struct sys_timer *sys_timer;
+
+static inline unsigned long get_timer_offset(void)
+{
+       return sys_timer->ops->get_offset();
+}
+
+static inline unsigned long get_timer_frequency(void)
+{
+       return sys_timer->ops->get_frequency();
+}
+
+/* arch/sh/kernel/timers/timer.c */
+struct sys_timer *get_sys_timer(void);
+
+/* arch/sh/kernel/time.c */
+void handle_timer_tick(struct pt_regs *);
+
+#endif /* __ASM_SH_TIMER_H */
+