diff options
Diffstat (limited to 'arch/i386/kernel/hpet.c')
| -rw-r--r-- | arch/i386/kernel/hpet.c | 496 |
1 files changed, 477 insertions, 19 deletions
diff --git a/arch/i386/kernel/hpet.c b/arch/i386/kernel/hpet.c index 7d2739fff3a..e1006b7acc9 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 |