[MIPS] i8253 PIT clocksource and clockevent drivers
Derived from the i386 variant with a few x86 complexities chopped off.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index d8c9058..f943736 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -65,6 +65,7 @@
bool "Cobalt Server"
select DMA_NONCOHERENT
select HW_HAS_PCI
+ select I8253
select I8259
select IRQ_CPU
select IRQ_GT641XX
@@ -112,6 +113,7 @@
select ARCH_MAY_HAVE_PC_FDC
select GENERIC_ISA_DMA
select IRQ_CPU
+ select I8253
select I8259
select ISA
select PCSPEAKER
@@ -201,6 +203,7 @@
select GENERIC_ISA_DMA
select IRQ_CPU
select HW_HAS_PCI
+ select I8253
select I8259
select MIPS_BOARDS_GEN
select MIPS_BONITO64
@@ -334,6 +337,7 @@
select DMA_COHERENT
select GENERIC_ISA_DMA
select HAVE_STD_PC_SERIAL_PORT
+ select I8253
select I8259
select IRQ_CPU
select ISA
@@ -362,6 +366,7 @@
select BOOT_ELF32
select DMA_NONCOHERENT
select HW_HAS_EISA
+ select I8253
select IP22_CPU_SCACHE
select IRQ_CPU
select GENERIC_ISA_DMA_SUPPORT_BROKEN
@@ -534,6 +539,7 @@
select HW_HAS_EISA
select HW_HAS_PCI
select IRQ_CPU
+ select I8253
select I8259
select ISA
select PCSPEAKER
@@ -1893,6 +1899,9 @@
bool
default y
+config I8253
+ bool
+
config PCSPEAKER
bool
diff --git a/arch/mips/cobalt/setup.c b/arch/mips/cobalt/setup.c
index 5d2e879..345e4ae 100644
--- a/arch/mips/cobalt/setup.c
+++ b/arch/mips/cobalt/setup.c
@@ -15,6 +15,7 @@
#include <asm/bootinfo.h>
#include <asm/time.h>
+#include <asm/i8253.h>
#include <asm/io.h>
#include <asm/reboot.h>
#include <asm/gt64120.h>
@@ -84,6 +85,11 @@
},
};
+void __init plat_time_init(void)
+{
+ setup_pit_timer();
+}
+
void __init plat_mem_setup(void)
{
int i;
diff --git a/arch/mips/jazz/setup.c b/arch/mips/jazz/setup.c
index fa890df..2a7ec08 100644
--- a/arch/mips/jazz/setup.c
+++ b/arch/mips/jazz/setup.c
@@ -25,6 +25,7 @@
#include <linux/serial_8250.h>
#include <asm/bootinfo.h>
+#include <asm/i8253.h>
#include <asm/irq.h>
#include <asm/jazz.h>
#include <asm/jazzdma.h>
@@ -63,6 +64,11 @@
}
};
+void __init plat_time_init(void)
+{
+ setup_pit_timer();
+}
+
void __init plat_mem_setup(void)
{
int i;
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 7851b4b..a2689f9 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -65,6 +65,7 @@
obj-$(CONFIG_64BIT) += cpu-bugs64.o
+obj-$(CONFIG_I8253) += i8253.o
obj-$(CONFIG_PCSPEAKER) += pcspeaker.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
diff --git a/arch/mips/kernel/i8253.c b/arch/mips/kernel/i8253.c
new file mode 100644
index 0000000..5d9830d
--- /dev/null
+++ b/arch/mips/kernel/i8253.c
@@ -0,0 +1,213 @@
+/*
+ * i8253.c 8253/PIT functions
+ *
+ */
+#include <linux/clockchips.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+
+#include <asm/delay.h>
+#include <asm/i8253.h>
+#include <asm/io.h>
+
+static DEFINE_SPINLOCK(i8253_lock);
+
+/*
+ * 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)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&i8253_lock, flags);
+
+ 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(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;
+ }
+ spin_unlock_irqrestore(&i8253_lock, flags);
+}
+
+/*
+ * 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)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&i8253_lock, flags);
+ outb_p(delta & 0xff , PIT_CH0); /* LSB */
+ outb(delta >> 8 , PIT_CH0); /* MSB */
+ spin_unlock_irqrestore(&i8253_lock, flags);
+
+ 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.
+ *
+ * The profiling and update capabilites are switched off once the local apic is
+ * registered. This mechanism replaces the previous #ifdef LOCAL_APIC -
+ * !using_apic_timer decisions in do_timer_interrupt_hook()
+ */
+struct clock_event_device pit_clockevent = {
+ .name = "pit",
+ .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+ .set_mode = init_pit_timer,
+ .set_next_event = pit_next_event,
+ .shift = 32,
+ .irq = 0,
+};
+
+irqreturn_t timer_interrupt(int irq, void *dev_id)
+{
+ pit_clockevent.event_handler(&pit_clockevent);
+
+ return IRQ_HANDLED;
+}
+
+static struct irqaction irq0 = {
+ .handler = timer_interrupt,
+ .flags = IRQF_DISABLED | IRQF_NOBALANCING,
+ .mask = CPU_MASK_NONE,
+ .name = "timer"
+};
+
+/*
+ * 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 setup_pit_timer(void)
+{
+ /*
+ * Start pit with the boot cpu mask and make it global after the
+ * IO_APIC has been initialized.
+ */
+ pit_clockevent.cpumask = cpumask_of_cpu(0);
+ pit_clockevent.mult = div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC, 32);
+ pit_clockevent.max_delta_ns =
+ clockevent_delta2ns(0x7FFF, &pit_clockevent);
+ pit_clockevent.min_delta_ns =
+ clockevent_delta2ns(0xF, &pit_clockevent);
+ clockevents_register_device(&pit_clockevent);
+
+ irq0.mask = cpumask_of_cpu(0);
+ setup_irq(0, &irq0);
+}
+
+/*
+ * Since the PIT overflows every tick, its not very useful
+ * to just read by itself. So use jiffies to emulate a free
+ * running counter:
+ */
+static cycle_t pit_read(void)
+{
+ unsigned long flags;
+ int count;
+ u32 jifs;
+ static int old_count;
+ static u32 old_jifs;
+
+ spin_lock_irqsave(&i8253_lock, flags);
+ /*
+ * Although our caller may have the read side of xtime_lock,
+ * this is now a seqlock, and we are cheating in this routine
+ * by having side effects on state that we cannot undo if
+ * there is a collision on the seqlock and our caller has to
+ * retry. (Namely, old_jifs and old_count.) So we must treat
+ * jiffies as volatile despite the lock. We read jiffies
+ * before latching the timer count to guarantee that although
+ * the jiffies value might be older than the count (that is,
+ * the counter may underflow between the last point where
+ * jiffies was incremented and the point where we latch the
+ * count), it cannot be newer.
+ */
+ jifs = jiffies;
+ 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_p(0x34, PIT_MODE);
+ outb_p(LATCH & 0xff, PIT_CH0);
+ outb(LATCH >> 8, PIT_CH0);
+ count = LATCH - 1;
+ }
+
+ /*
+ * It's possible for count to appear to go the wrong way for a
+ * couple of reasons:
+ *
+ * 1. The timer counter underflows, but we haven't handled the
+ * resulting interrupt and incremented jiffies yet.
+ * 2. Hardware problem with the timer, not giving us continuous time,
+ * the counter does small "jumps" upwards on some Pentium systems,
+ * (see c't 95/10 page 335 for Neptun bug.)
+ *
+ * Previous attempts to handle these cases intelligently were
+ * buggy, so we just do the simple thing now.
+ */
+ if (count > old_count && jifs == old_jifs) {
+ count = old_count;
+ }
+ old_count = count;
+ old_jifs = jifs;
+
+ spin_unlock_irqrestore(&i8253_lock, flags);
+
+ count = (LATCH - 1) - count;
+
+ return (cycle_t)(jifs * LATCH) + count;
+}
+
+static struct clocksource clocksource_pit = {
+ .name = "pit",
+ .rating = 110,
+ .read = pit_read,
+ .mask = CLOCKSOURCE_MASK(32),
+ .mult = 0,
+ .shift = 20,
+};
+
+static int __init init_pit_clocksource(void)
+{
+ if (num_possible_cpus() > 1) /* PIT does not scale! */
+ return 0;
+
+ clocksource_pit.mult = clocksource_hz2mult(CLOCK_TICK_RATE, 20);
+ return clocksource_register(&clocksource_pit);
+}
+arch_initcall(init_pit_clocksource);
diff --git a/arch/mips/mips-boards/generic/time.c b/arch/mips/mips-boards/generic/time.c
index cf55ecd..4fab3b2 100644
--- a/arch/mips/mips-boards/generic/time.c
+++ b/arch/mips/mips-boards/generic/time.c
@@ -31,6 +31,7 @@
#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
#include <asm/hardirq.h>
+#include <asm/i8253.h>
#include <asm/irq.h>
#include <asm/div64.h>
#include <asm/cpu.h>
@@ -141,6 +142,9 @@
cpu_khz = est_freq / 1000;
mips_scroll_message();
+#ifdef CONFIG_I8253 /* Only Malta has a PIT */
+ setup_pit_timer();
+#endif
}
//static irqreturn_t mips_perf_interrupt(int irq, void *dev_id)
diff --git a/arch/mips/qemu/q-setup.c b/arch/mips/qemu/q-setup.c
index 89a2076..23d34c1 100644
--- a/arch/mips/qemu/q-setup.c
+++ b/arch/mips/qemu/q-setup.c
@@ -1,4 +1,6 @@
#include <linux/init.h>
+
+#include <asm/i8253.h>
#include <asm/io.h>
#include <asm/time.h>
@@ -11,12 +13,9 @@
return "Qemu";
}
-void __init plat_timer_setup(struct irqaction *irq)
+void __init plat_time_init(void)
{
- /* set the clock to 100 Hz */
- outb_p(0x34,0x43); /* binary, mode 2, LSB/MSB, ch 0 */
- outb_p(LATCH & 0xff , 0x40); /* LSB */
- outb(LATCH >> 8 , 0x40); /* MSB */
+ setup_pit_timer();
}
void __init plat_mem_setup(void)
diff --git a/arch/mips/sgi-ip22/ip22-time.c b/arch/mips/sgi-ip22/ip22-time.c
index a1df1f9..9b9bffd 100644
--- a/arch/mips/sgi-ip22/ip22-time.c
+++ b/arch/mips/sgi-ip22/ip22-time.c
@@ -20,6 +20,7 @@
#include <asm/cpu.h>
#include <asm/mipsregs.h>
+#include <asm/i8253.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/time.h>
@@ -172,6 +173,9 @@
(int) (r4k_tick % (500000 / HZ)));
mips_hpt_frequency = r4k_tick * HZ;
+
+ if (ip22_is_fullhouse())
+ setup_pit_timer();
}
/* Generic SGI handler for (spurious) 8254 interrupts */
diff --git a/arch/mips/sni/time.c b/arch/mips/sni/time.c
index 92452d6..153f065 100644
--- a/arch/mips/sni/time.c
+++ b/arch/mips/sni/time.c
@@ -2,6 +2,7 @@
#include <linux/interrupt.h>
#include <linux/time.h>
+#include <asm/i8253.h>
#include <asm/sni.h>
#include <asm/time.h>
#include <asm-generic/rtc.h>
@@ -116,6 +117,8 @@
(int) (r4k_tick % (500000 / HZ)));
mips_hpt_frequency = r4k_tick * HZ;
+
+ setup_pit_timer();
}
/*
diff --git a/include/asm-mips/i8253.h b/include/asm-mips/i8253.h
new file mode 100644
index 0000000..8f689d7
--- /dev/null
+++ b/include/asm-mips/i8253.h
@@ -0,0 +1,30 @@
+/*
+ * Machine specific IO port address definition for generic.
+ * Written by Osamu Tomita <tomita@cinet.co.jp>
+ */
+#ifndef _MACH_IO_PORTS_H
+#define _MACH_IO_PORTS_H
+
+/* i8253A PIT registers */
+#define PIT_MODE 0x43
+#define PIT_CH0 0x40
+#define PIT_CH2 0x42
+
+/* i8259A PIC registers */
+#define PIC_MASTER_CMD 0x20
+#define PIC_MASTER_IMR 0x21
+#define PIC_MASTER_ISR PIC_MASTER_CMD
+#define PIC_MASTER_POLL PIC_MASTER_ISR
+#define PIC_MASTER_OCW3 PIC_MASTER_ISR
+#define PIC_SLAVE_CMD 0xa0
+#define PIC_SLAVE_IMR 0xa1
+
+/* i8259A PIC related value */
+#define PIC_CASCADE_IR 2
+#define MASTER_ICW4_DEFAULT 0x01
+#define SLAVE_ICW4_DEFAULT 0x01
+#define PIC_ICW4_AEOI 2
+
+extern void setup_pit_timer(void);
+
+#endif /* !_MACH_IO_PORTS_H */