i8253: Create common clockevent implementation

arm, mips and x86 implement i8253 based clockevents. All the same code
copied. Create a common implementation in drivers/clocksource/i8253.c.

About time to rename drivers/clocksource/ to something else.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20110609130621.921710458@linutronix.de

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 330343bcb67ea712c1b1a00b20fcaf1a28c73106..d8d3e02b912cabab39b1499436705e586f37f2ac 100644 (file)
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -1,11 +1,14 @@
 config CLKSRC_I8253
        bool
 
+config CLKEVT_I8253
+       bool
+
 config I8253_LOCK
        bool
 
 config CLKBLD_I8253
-       def_bool y if CLKSRC_I8253 || I8253_LOCK
+       def_bool y if CLKSRC_I8253 || CLKEVT_I8253 || I8253_LOCK
 
 config CLKSRC_MMIO
        bool

diff --git a/drivers/clocksource/i8253.c b/drivers/clocksource/i8253.c
index e594f52eb88ecb1eb87c80aacf35d6be8a5560ed..27c49e60b7d651e74818567d807e162fb00a298d 100644 (file)
--- a/drivers/clocksource/i8253.c
+++ b/drivers/clocksource/i8253.c
@@ -1,13 +1,14 @@
 /*
  * i8253 PIT clocksource
  */
-#include <linux/clocksource.h>
+#include <linux/clockchips.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/spinlock.h>
 #include <linux/timex.h>
 #include <linux/module.h>
 #include <linux/i8253.h>
+#include <linux/smp.h>
 
 /*
  * Protects access to I/O ports
@@ -47,15 +48,15 @@ static cycle_t i8253_read(struct clocksource *cs)
         * count), it cannot be newer.
         */
        jifs = jiffies;
-       outb_pit(0x00, PIT_MODE);       /* latch the count ASAP */
-       count = inb_pit(PIT_CH0);       /* read the latched count */
-       count |= inb_pit(PIT_CH0) << 8;
+       outb_p(0x00, PIT_MODE); /* latch the count ASAP */
+       count = inb_p(PIT_CH0); /* read the latched count */
+       count |= inb_p(PIT_CH0) << 8;
 
        /* VIA686a test code... reset the latch if count > max + 1 */
        if (count > LATCH) {
-               outb_pit(0x34, PIT_MODE);
-               outb_pit(PIT_LATCH & 0xff, PIT_CH0);
-               outb_pit(PIT_LATCH >> 8, PIT_CH0);
+               outb_p(0x34, PIT_MODE);
+               outb_p(PIT_LATCH & 0xff, PIT_CH0);
+               outb_p(PIT_LATCH >> 8, PIT_CH0);
                count = PIT_LATCH - 1;
        }
 
@@ -97,3 +98,89 @@ int __init clocksource_i8253_init(void)
        return clocksource_register_hz(&i8253_cs, PIT_TICK_RATE);
 }
 #endif
+
+#ifdef CONFIG_CLKEVT_I8253
+/*
+ * Initialize the PIT timer.
+ *
+ * This is also called after resume to bring the PIT into operation again.
+ */
+static void init_pit_timer(enum clock_event_mode mode,
+                          struct clock_event_device *evt)
+{
+       raw_spin_lock(&i8253_lock);
+
+       switch (mode) {
+       case CLOCK_EVT_MODE_PERIODIC:
+               /* binary, mode 2, LSB/MSB, ch 0 */
+               outb_p(0x34, PIT_MODE);
+               outb_p(LATCH & 0xff , PIT_CH0); /* LSB */
+               outb_p(LATCH >> 8 , PIT_CH0);           /* MSB */
+               break;
+
+       case CLOCK_EVT_MODE_SHUTDOWN:
+       case CLOCK_EVT_MODE_UNUSED:
+               if (evt->mode == CLOCK_EVT_MODE_PERIODIC ||
+                   evt->mode == CLOCK_EVT_MODE_ONESHOT) {
+                       outb_p(0x30, PIT_MODE);
+                       outb_p(0, PIT_CH0);
+                       outb_p(0, PIT_CH0);
+               }
+               break;
+
+       case CLOCK_EVT_MODE_ONESHOT:
+               /* One shot setup */
+               outb_p(0x38, PIT_MODE);
+               break;
+
+       case CLOCK_EVT_MODE_RESUME:
+               /* Nothing to do here */
+               break;
+       }
+       raw_spin_unlock(&i8253_lock);
+}
+
+/*
+ * Program the next event in oneshot mode
+ *
+ * Delta is given in PIT ticks
+ */
+static int pit_next_event(unsigned long delta, struct clock_event_device *evt)
+{
+       raw_spin_lock(&i8253_lock);
+       outb_p(delta & 0xff , PIT_CH0); /* LSB */
+       outb_p(delta >> 8 , PIT_CH0);           /* MSB */
+       raw_spin_unlock(&i8253_lock);
+
+       return 0;
+}
+
+/*
+ * On UP the PIT can serve all of the possible timer functions. On SMP systems
+ * it can be solely used for the global tick.
+ */
+struct clock_event_device i8253_clockevent = {
+       .name           = "pit",
+       .features       = CLOCK_EVT_FEAT_PERIODIC,
+       .set_mode       = init_pit_timer,
+       .set_next_event = pit_next_event,
+};
+
+/*
+ * Initialize the conversion factor and the min/max deltas of the clock event
+ * structure and register the clock event source with the framework.
+ */
+void __init clockevent_i8253_init(bool oneshot)
+{
+       if (oneshot)
+               i8253_clockevent.features |= CLOCK_EVT_FEAT_ONESHOT;
+       /*
+        * Start pit with the boot cpu mask. x86 might make it global
+        * when it is used as broadcast device later.
+        */
+       i8253_clockevent.cpumask = cpumask_of(smp_processor_id());
+
+       clockevents_config_and_register(&i8253_clockevent, PIT_TICK_RATE,
+                                       0xF, 0x7FFF);
+}
+#endif

diff --git a/include/linux/i8253.h b/include/linux/i8253.h
index 76039c86ab58efb80d95333ddd0d367bf20b866d..487d50c7db39fd9b7dc8743f802c81c08a7ec015 100644 (file)
--- a/include/linux/i8253.h
+++ b/include/linux/i8253.h
@@ -24,6 +24,8 @@
 #define outb_pit        outb_p
 
 extern raw_spinlock_t i8253_lock;
+extern struct clock_event_device i8253_clockevent;
+extern void clockevent_i8253_init(bool oneshot);
 
 extern void setup_pit_timer(void);