[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 7d2739fff3a3..e1006b7acc9e 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