[PATCH] clockevents: i386 drivers

Add clockevent drivers for i386: lapic (local) and PIT/HPET (global).  Update
the timer IRQ to call into the PIT/HPET driver's event handler and the
lapic-timer IRQ to call into the lapic clockevent driver.  The assignement of
timer functionality is delegated to the core framework code and replaces the
compile and runtime evalution in do_timer_interrupt_hook()

Use the clockevents broadcast support and implement the lapic_broadcast
function for ACPI.

No changes to existing functionality.

[ kdump fix from Vivek Goyal <vgoyal@in.ibm.com> ]
[ fixes based on review feedback from Arjan van de Ven <arjan@infradead.org> ]
Cleanups-from: Adrian Bunk <bunk@stusta.de>
Build-fixes-from: Andrew Morton <akpm@osdl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 477 insertions, 19 deletions

diff --git a/arch/i386/kernel/hpet.c b/arch/i386/kernel/hpet.c
index 7d2739f..e1006b7 100644
--- a/arch/i386/kernel/hpet.c
+++ b/arch/i386/kernel/hpet.c
@@ -1,4 +1,5 @@
 #include <linux/clocksource.h>
+#include <linux/clockchips.h>
 #include <linux/errno.h>
 #include <linux/hpet.h>
 #include <linux/init.h>
@@ -6,17 +7,278 @@
 #include <asm/hpet.h>
 #include <asm/io.h>
 
+extern struct clock_event_device *global_clock_event;
+
 #define HPET_MASK	CLOCKSOURCE_MASK(32)
 #define HPET_SHIFT	22
 
 /* FSEC = 10^-15 NSEC = 10^-9 */
 #define FSEC_PER_NSEC	1000000
 
-static void __iomem *hpet_ptr;
+/*
+ * HPET address is set in acpi/boot.c, when an ACPI entry exists
+ */
+unsigned long hpet_address;
+static void __iomem * hpet_virt_address;
+
+static inline unsigned long hpet_readl(unsigned long a)
+{
+	return readl(hpet_virt_address + a);
+}
+
+static inline void hpet_writel(unsigned long d, unsigned long a)
+{
+	writel(d, hpet_virt_address + a);
+}
+
+/*
+ * HPET command line enable / disable
+ */
+static int boot_hpet_disable;
+
+static int __init hpet_setup(char* str)
+{
+	if (str) {
+		if (!strncmp("disable", str, 7))
+			boot_hpet_disable = 1;
+	}
+	return 1;
+}
+__setup("hpet=", hpet_setup);
+
+static inline int is_hpet_capable(void)
+{
+	return (!boot_hpet_disable && hpet_address);
+}
+
+/*
+ * HPET timer interrupt enable / disable
+ */
+static int hpet_legacy_int_enabled;
+
+/**
+ * is_hpet_enabled - check whether the hpet timer interrupt is enabled
+ */
+int is_hpet_enabled(void)
+{
+	return is_hpet_capable() && hpet_legacy_int_enabled;
+}
+
+/*
+ * When the hpet driver (/dev/hpet) is enabled, we need to reserve
+ * timer 0 and timer 1 in case of RTC emulation.
+ */
+#ifdef CONFIG_HPET
+static void hpet_reserve_platform_timers(unsigned long id)
+{
+	struct hpet __iomem *hpet = hpet_virt_address;
+	struct hpet_timer __iomem *timer = &hpet->hpet_timers[2];
+	unsigned int nrtimers, i;
+	struct hpet_data hd;
+
+	nrtimers = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT) + 1;
+
+	memset(&hd, 0, sizeof (hd));
+	hd.hd_phys_address = hpet_address;
+	hd.hd_address = hpet_virt_address;
+	hd.hd_nirqs = nrtimers;
+	hd.hd_flags = HPET_DATA_PLATFORM;
+	hpet_reserve_timer(&hd, 0);
+
+#ifdef CONFIG_HPET_EMULATE_RTC
+	hpet_reserve_timer(&hd, 1);
+#endif
+
+	hd.hd_irq[0] = HPET_LEGACY_8254;
+	hd.hd_irq[1] = HPET_LEGACY_RTC;
+
+	for (i = 2; i < nrtimers; timer++, i++)
+		hd.hd_irq[i] = (timer->hpet_config & Tn_INT_ROUTE_CNF_MASK) >>
+			Tn_INT_ROUTE_CNF_SHIFT;
+
+	hpet_alloc(&hd);
+
+}
+#else
+static void hpet_reserve_platform_timers(unsigned long id) { }
+#endif
+
+/*
+ * Common hpet info
+ */
+static unsigned long hpet_period;
+
+static void hpet_set_mode(enum clock_event_mode mode,
+			  struct clock_event_device *evt);
+static int hpet_next_event(unsigned long delta,
+			   struct clock_event_device *evt);
+
+/*
+ * The hpet clock event device
+ */
+static struct clock_event_device hpet_clockevent = {
+	.name		= "hpet",
+	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+	.set_mode	= hpet_set_mode,
+	.set_next_event = hpet_next_event,
+	.shift		= 32,
+	.irq		= 0,
+};
+
+static void hpet_start_counter(void)
+{
+	unsigned long cfg = hpet_readl(HPET_CFG);
+
+	cfg &= ~HPET_CFG_ENABLE;
+	hpet_writel(cfg, HPET_CFG);
+	hpet_writel(0, HPET_COUNTER);
+	hpet_writel(0, HPET_COUNTER + 4);
+	cfg |= HPET_CFG_ENABLE;
+	hpet_writel(cfg, HPET_CFG);
+}
+
+static void hpet_enable_int(void)
+{
+	unsigned long cfg = hpet_readl(HPET_CFG);
+
+	cfg |= HPET_CFG_LEGACY;
+	hpet_writel(cfg, HPET_CFG);
+	hpet_legacy_int_enabled = 1;
+}
+
+static void hpet_set_mode(enum clock_event_mode mode,
+			  struct clock_event_device *evt)
+{
+	unsigned long cfg, cmp, now;
+	uint64_t delta;
+
+	switch(mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		delta = ((uint64_t)(NSEC_PER_SEC/HZ)) * hpet_clockevent.mult;
+		delta >>= hpet_clockevent.shift;
+		now = hpet_readl(HPET_COUNTER);
+		cmp = now + (unsigned long) delta;
+		cfg = hpet_readl(HPET_T0_CFG);
+		cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC |
+		       HPET_TN_SETVAL | HPET_TN_32BIT;
+		hpet_writel(cfg, HPET_T0_CFG);
+		/*
+		 * The first write after writing TN_SETVAL to the
+		 * config register sets the counter value, the second
+		 * write sets the period.
+		 */
+		hpet_writel(cmp, HPET_T0_CMP);
+		udelay(1);
+		hpet_writel((unsigned long) delta, HPET_T0_CMP);
+		break;
+
+	case CLOCK_EVT_MODE_ONESHOT:
+		cfg = hpet_readl(HPET_T0_CFG);
+		cfg &= ~HPET_TN_PERIODIC;
+		cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
+		hpet_writel(cfg, HPET_T0_CFG);
+		break;
+
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+		cfg = hpet_readl(HPET_T0_CFG);
+		cfg &= ~HPET_TN_ENABLE;
+		hpet_writel(cfg, HPET_T0_CFG);
+		break;
+	}
+}
+
+static int hpet_next_event(unsigned long delta,
+			   struct clock_event_device *evt)
+{
+	unsigned long cnt;
+
+	cnt = hpet_readl(HPET_COUNTER);
+	cnt += delta;
+	hpet_writel(cnt, HPET_T0_CMP);
+
+	return ((long)(hpet_readl(HPET_COUNTER) - cnt ) > 0);
+}
+
+/*
+ * Try to setup the HPET timer
+ */
+int __init hpet_enable(void)
+{
+	unsigned long id;
+	uint64_t hpet_freq;
+
+	if (!is_hpet_capable())
+		return 0;
+
+	hpet_virt_address = ioremap_nocache(hpet_address, HPET_MMAP_SIZE);
+
+	/*
+	 * Read the period and check for a sane value:
+	 */
+	hpet_period = hpet_readl(HPET_PERIOD);
+	if (hpet_period < HPET_MIN_PERIOD || hpet_period > HPET_MAX_PERIOD)
+		goto out_nohpet;
+
+	/*
+	 * The period is a femto seconds value. We need to calculate the
+	 * scaled math multiplication factor for nanosecond to hpet tick
+	 * conversion.
+	 */
+	hpet_freq = 1000000000000000ULL;
+	do_div(hpet_freq, hpet_period);
+	hpet_clockevent.mult = div_sc((unsigned long) hpet_freq,
+				      NSEC_PER_SEC, 32);
+	/* Calculate the min / max delta */
+	hpet_clockevent.max_delta_ns = clockevent_delta2ns(0x7FFFFFFF,
+							   &hpet_clockevent);
+	hpet_clockevent.min_delta_ns = clockevent_delta2ns(0x30,
+							   &hpet_clockevent);
+
+	/*
+	 * Read the HPET ID register to retrieve the IRQ routing
+	 * information and the number of channels
+	 */
+	id = hpet_readl(HPET_ID);
+
+#ifdef CONFIG_HPET_EMULATE_RTC
+	/*
+	 * The legacy routing mode needs at least two channels, tick timer
+	 * and the rtc emulation channel.
+	 */
+	if (!(id & HPET_ID_NUMBER))
+		goto out_nohpet;
+#endif
+
+	/* Start the counter */
+	hpet_start_counter();
+
+	if (id & HPET_ID_LEGSUP) {
+		hpet_enable_int();
+		hpet_reserve_platform_timers(id);
+		/*
+		 * Start hpet with the boot cpu mask and make it
+		 * global after the IO_APIC has been initialized.
+		 */
+		hpet_clockevent.cpumask =cpumask_of_cpu(0);
+		clockevents_register_device(&hpet_clockevent);
+		global_clock_event = &hpet_clockevent;
+		return 1;
+	}
+	return 0;
 
+out_nohpet:
+	iounmap(hpet_virt_address);
+	hpet_virt_address = NULL;
+	return 0;
+}
+
+/*
+ * Clock source related code
+ */
 static cycle_t read_hpet(void)
 {
-	return (cycle_t)readl(hpet_ptr);
+	return (cycle_t)hpet_readl(HPET_COUNTER);
 }
 
 static struct clocksource clocksource_hpet = {
@@ -24,28 +286,17 @@ static struct clocksource clocksource_hpet = {
 	.rating		= 250,
 	.read		= read_hpet,
 	.mask		= HPET_MASK,
-	.mult		= 0, /* set below */
 	.shift		= HPET_SHIFT,
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
 static int __init init_hpet_clocksource(void)
 {
-	unsigned long hpet_period;
-	void __iomem* hpet_base;
 	u64 tmp;
-	int err;
 
-	if (!is_hpet_enabled())
+	if (!hpet_virt_address)
 		return -ENODEV;
 
-	/* calculate the hpet address: */
-	hpet_base = ioremap_nocache(hpet_address, HPET_MMAP_SIZE);
-	hpet_ptr = hpet_base + HPET_COUNTER;
-
-	/* calculate the frequency: */
-	hpet_period = readl(hpet_base + HPET_PERIOD);
-
 	/*
 	 * hpet period is in femto seconds per cycle
 	 * so we need to convert this to ns/cyc units
@@ -61,11 +312,218 @@ static int __init init_hpet_clocksource(void)
 	do_div(tmp, FSEC_PER_NSEC);
 	clocksource_hpet.mult = (u32)tmp;
 
-	err = clocksource_register(&clocksource_hpet);
-	if (err)
-		iounmap(hpet_base);
-
-	return err;
+	return clocksource_register(&clocksource_hpet);
 }
 
 module_init(init_hpet_clocksource);
+
+#ifdef CONFIG_HPET_EMULATE_RTC
+
+/* HPET in LegacyReplacement Mode eats up RTC interrupt line. When, HPET
+ * is enabled, we support RTC interrupt functionality in software.
+ * RTC has 3 kinds of interrupts:
+ * 1) Update Interrupt - generate an interrupt, every sec, when RTC clock
+ *    is updated
+ * 2) Alarm Interrupt - generate an interrupt at a specific time of day
+ * 3) Periodic Interrupt - generate periodic interrupt, with frequencies
+ *    2Hz-8192Hz (2Hz-64Hz for non-root user) (all freqs in powers of 2)
+ * (1) and (2) above are implemented using polling at a frequency of
+ * 64 Hz. The exact frequency is a tradeoff between accuracy and interrupt
+ * overhead. (DEFAULT_RTC_INT_FREQ)
+ * For (3), we use interrupts at 64Hz or user specified periodic
+ * frequency, whichever is higher.
+ */
+#include <linux/mc146818rtc.h>
+#include <linux/rtc.h>
+
+#define DEFAULT_RTC_INT_FREQ	64
+#define DEFAULT_RTC_SHIFT	6
+#define RTC_NUM_INTS		1
+
+static unsigned long hpet_rtc_flags;
+static unsigned long hpet_prev_update_sec;
+static struct rtc_time hpet_alarm_time;
+static unsigned long hpet_pie_count;
+static unsigned long hpet_t1_cmp;
+static unsigned long hpet_default_delta;
+static unsigned long hpet_pie_delta;
+static unsigned long hpet_pie_limit;
+
+/*
+ * Timer 1 for RTC emulation. We use one shot mode, as periodic mode
+ * is not supported by all HPET implementations for timer 1.
+ *
+ * hpet_rtc_timer_init() is called when the rtc is initialized.
+ */
+int hpet_rtc_timer_init(void)
+{
+	unsigned long cfg, cnt, delta, flags;
+
+	if (!is_hpet_enabled())
+		return 0;
+
+	if (!hpet_default_delta) {
+		uint64_t clc;
+
+		clc = (uint64_t) hpet_clockevent.mult * NSEC_PER_SEC;
+		clc >>= hpet_clockevent.shift + DEFAULT_RTC_SHIFT;
+		hpet_default_delta = (unsigned long) clc;
+	}
+
+	if (!(hpet_rtc_flags & RTC_PIE) || hpet_pie_limit)
+		delta = hpet_default_delta;
+	else
+		delta = hpet_pie_delta;
+
+	local_irq_save(flags);
+
+	cnt = delta + hpet_readl(HPET_COUNTER);
+	hpet_writel(cnt, HPET_T1_CMP);
+	hpet_t1_cmp = cnt;
+
+	cfg = hpet_readl(HPET_T1_CFG);
+	cfg &= ~HPET_TN_PERIODIC;
+	cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
+	hpet_writel(cfg, HPET_T1_CFG);
+
+	local_irq_restore(flags);
+
+	return 1;
+}
+
+/*
+ * The functions below are called from rtc driver.
+ * Return 0 if HPET is not being used.
+ * Otherwise do the necessary changes and return 1.
+ */
+int hpet_mask_rtc_irq_bit(unsigned long bit_mask)
+{
+	if (!is_hpet_enabled())
+		return 0;
+
+	hpet_rtc_flags &= ~bit_mask;
+	return 1;
+}
+
+int hpet_set_rtc_irq_bit(unsigned long bit_mask)
+{
+	unsigned long oldbits = hpet_rtc_flags;
+
+	if (!is_hpet_enabled())
+		return 0;
+
+	hpet_rtc_flags |= bit_mask;
+
+	if (!oldbits)
+		hpet_rtc_timer_init();
+
+	return 1;
+}
+
+int hpet_set_alarm_time(unsigned char hrs, unsigned char min,
+			unsigned char sec)
+{
+	if (!is_hpet_enabled())
+		return 0;
+
+	hpet_alarm_time.tm_hour = hrs;
+	hpet_alarm_time.tm_min = min;
+	hpet_alarm_time.tm_sec = sec;
+
+	return 1;
+}
+
+int hpet_set_periodic_freq(unsigned long freq)
+{
+	uint64_t clc;
+
+	if (!is_hpet_enabled())
+		return 0;
+
+	if (freq <= DEFAULT_RTC_INT_FREQ)
+		hpet_pie_limit = DEFAULT_RTC_INT_FREQ / freq;
+	else {
+		clc = (uint64_t) hpet_clockevent.mult * NSEC_PER_SEC;
+		do_div(clc, freq);
+		clc >>= hpet_clockevent.shift;
+		hpet_pie_delta = (unsigned long) clc;
+	}
+	return 1;
+}
+
+int hpet_rtc_dropped_irq(void)
+{
+	return is_hpet_enabled();
+}
+
+static void hpet_rtc_timer_reinit(void)
+{
+	unsigned long cfg, delta;
+	int lost_ints = -1;
+
+	if (unlikely(!hpet_rtc_flags)) {
+		cfg = hpet_readl(HPET_T1_CFG);
+		cfg &= ~HPET_TN_ENABLE;
+		hpet_writel(cfg, HPET_T1_CFG);
+		return;
+	}
+
+	if (!(hpet_rtc_flags & RTC_PIE) || hpet_pie_limit)
+		delta = hpet_default_delta;
+	else
+		delta = hpet_pie_delta;
+
+	/*
+	 * Increment the comparator value until we are ahead of the
+	 * current count.
+	 */
+	do {
+		hpet_t1_cmp += delta;
+		hpet_writel(hpet_t1_cmp, HPET_T1_CMP);
+		lost_ints++;
+	} while ((long)(hpet_readl(HPET_COUNTER) - hpet_t1_cmp) > 0);
+
+	if (lost_ints) {
+		if (hpet_rtc_flags & RTC_PIE)
+			hpet_pie_count += lost_ints;
+		if (printk_ratelimit())
+			printk(KERN_WARNING "rtc: lost %d interrupts\n",
+				lost_ints);
+	}
+}
+
+irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
+{
+	struct rtc_time curr_time;
+	unsigned long rtc_int_flag = 0;
+
+	hpet_rtc_timer_reinit();
+
+	if (hpet_rtc_flags & (RTC_UIE | RTC_AIE))
+		rtc_get_rtc_time(&curr_time);
+
+	if (hpet_rtc_flags & RTC_UIE &&
+	    curr_time.tm_sec != hpet_prev_update_sec) {
+		rtc_int_flag = RTC_UF;
+		hpet_prev_update_sec = curr_time.tm_sec;
+	}
+
+	if (hpet_rtc_flags & RTC_PIE &&
+	    ++hpet_pie_count >= hpet_pie_limit) {
+		rtc_int_flag |= RTC_PF;
+		hpet_pie_count = 0;
+	}
+
+	if (hpet_rtc_flags & RTC_PIE &&
+	    (curr_time.tm_sec == hpet_alarm_time.tm_sec) &&
+	    (curr_time.tm_min == hpet_alarm_time.tm_min) &&
+	    (curr_time.tm_hour == hpet_alarm_time.tm_hour))
+			rtc_int_flag |= RTC_AF;
+
+	if (rtc_int_flag) {
+		rtc_int_flag |= (RTC_IRQF | (RTC_NUM_INTS << 8));
+		rtc_interrupt(rtc_int_flag, dev_id);
+	}
+	return IRQ_HANDLED;
+}
+#endif