kern/drivers/timers/hpet.c - akaros - Git at Google

 /* Copyright (c) 2020 Google Inc
  * Copyright (c) 2014 The Regents of the University of California
  * Barret Rhoden <brho@cs.berkeley.edu>
  * See LICENSE for details.
  *
  * HPET nonsense */

 #include <string.h>
 #include <stdio.h>
 #include <assert.h>
 #include <endian.h>
 #include <pmap.h>
 #include <acpi.h>
 #include <kmalloc.h>

 #include "hpet.h"

 #define HPET_BLOCK_LEN		1024

 #define HPET_CAP_ID		0x00
 #define HPET_CONFIG		0x10
 #define HPET_IRQ_STS		0x20
 #define HPET_MAIN_COUNTER	0xf0

 #define HPET_CONF_LEG_RT_CNF	(1 << 1)
 #define HPET_CONF_ENABLE_CNF	(1 << 0)

 #define HPET_TIMER_CONF		0x00
 #define HPET_TIMER_COMP		0x08
 #define HPET_TIMER_FSB		0x10

 #define HPET_TN_INT_TYPE_CNF	(1 << 1)
 #define HPET_TN_INT_ENB_CNF	(1 << 2)
 #define HPET_TN_TYPE_CNF	(1 << 3)
 #define HPET_TN_PER_INT_CAP	(1 << 4)
 #define HPET_TN_SIZE_CAP	(1 << 5)
 #define HPET_TN_VAL_SET_CNF	(1 << 6)
 #define HPET_TN_32MODE_CNF	(1 << 8)
 #define HPET_TN_INT_ROUTE_CNF	(0x1f << 9)
 #define HPET_TN_FSB_EN_CNF	(1 << 14)
 #define HPET_TN_FSB_INT_DEL_CAP	(1 << 15)
 #define HPET_TN_INT_ROUTE_CAP	(0xffffffffULL << 32)

 static struct hpet_block *gbl_hpet;

 /* The HPET likes 64bit mmreg reads and writes.  If the arch doesn't support
  * them, then things are a little trickier.  Probably just replace these with
  * mm64 ops, and quit supporting 32 bit. */
 static inline void hpet_w64(uintptr_t reg, uint64_t val)
 {
 	*((volatile uint64_t*)reg) = val;
 }

 static inline uint64_t hpet_r64(uintptr_t reg)
 {
 	return *((volatile uint64_t*)reg);
 }

 void hpet_timer_enable(struct hpet_timer *ht)
 {
 	hpet_w64(ht->base + HPET_TIMER_CONF, ht->enable_cmd);
 }

 void hpet_timer_disable(struct hpet_timer *ht)
 {
 	hpet_w64(ht->base + HPET_TIMER_CONF, 0);
 }

 /* This only works on 64 bit counters, where we don't have to deal with
  * wrap-around. */
 bool hpet_check_spurious_64(struct hpet_timer *ht)
 {
 	return hpet_r64(ht->hpb->base + HPET_MAIN_COUNTER) <
 		hpet_r64(ht->base + HPET_TIMER_COMP);
 }

 /* There is no upper addr!  But o/w, this is basically MSI.  To be fair, we zero
  * out the upper addr in msi.c too. */
 static uint64_t fsb_make_addr(uint8_t dest)
 {
 	return 0xfee00000 | (dest << 12);
 }

 /* dmode: e.g. 000 = fixed, 100 = NMI.  Assuming edge triggered */
 static uint64_t fsb_make_data(uint8_t vno, uint8_t dmode)
 {
 	return (dmode << 8) | vno;
 }

 /* This is a very limited HPET timer, primarily used by the watchdog.
  *
  * It's a one-shot (non-periodic), FSB, 64-bit, edge-triggered timer for Core 0
  * with vector vno and delivery mode dmode.
  *
  * Why so specific?  Okay, the HPET is a piece of shit, at least on my machine.
  * If you disable the interrupt, and then the time comes where MAIN == COMP, the
  * IRQ will be suppressed, but when you enable later on, the IRQ will fire.  No
  * way around it that I can find.
  *
  * One trick is to set the COMP to some time that won't fire, i.e.  in the past.
  * However, the 32 bit counters are only about a 5 minute reach.  So this trick
  * only works with the 64 bit counter.
  *
  * However, even with that, if the IRQ ever legitimately fires, any time you
  * reenable the timer, it triggers an IRQ.
  *
  * This is all with FSB (which has to be edge triggered) interrupt styles.  I
  * tried various combos of "write to the IRQ_STS register", change certain
  * fields in timer CONF, disable the global counter while making changes, etc.
  * All things that aren't in the book, but that might clear whatever internal
  * bit is set.
  *
  * Ultimately, I opted to handle the 'spurious' interrupt in SW, though with a 5
  * minute reach, you can't tell between an old value and a new one.  Unless you
  * use a 64 bit counter - then wraparound isn't a concern.  If we wanted to do
  * this for a 32 bit counter, we'd need to drastically limit the reach. */
 void hpet_magic_timer_setup(struct hpet_timer *ht, uint8_t vno, uint8_t dmode)
 {
 	/* Unlike the other reserved bits in the hpb's registers, the spec says
 	 * that timer (ht) conf reserved bits should be set to 0.
 	 *
 	 * In lieu of screwing around too much, we just set the entire register
 	 * in one shot.  Disabled = 0, enabled = all bits needed.  The
 	 * disastrous behavior mentioned above occurs regardless of the
 	 * technique used. */
 	hpet_timer_disable(ht);

 	/* Core 0, fixed, with vno */
 	hpet_w64(ht->base + HPET_TIMER_FSB,
 		 (fsb_make_addr(0) << 32) | fsb_make_data(vno, dmode));

 	ht->enable_cmd = HPET_TN_FSB_EN_CNF | HPET_TN_INT_ENB_CNF;
 }

 /* Sets the time to fire X ns in the future.  No guarantees or sanity checks.
  * If we get delayed setting this, the main counter may pass by our ticks value
  * before we write it, and you'll never get it. */
 void hpet_timer_increment_comparator(struct hpet_timer *ht, uint64_t nsec)
 {
 	uint64_t ticks;

 	ticks = hpet_r64(ht->hpb->base + HPET_MAIN_COUNTER);
 	ticks += nsec / ht->hpb->nsec_per_tick;
 	hpet_w64(ht->base + HPET_TIMER_COMP, ticks);
 }

 /* See above.  Need 64 bit and FSB */
 struct hpet_timer *hpet_get_magic_timer(void)
 {
 	struct hpet_block *hpb = gbl_hpet;
 	struct hpet_timer *ret = NULL;

 	if (!hpb)
 		return NULL;
 	spin_lock(&hpb->lock);
 	for (int i = 0; i < hpb->nr_timers; i++) {
 		struct hpet_timer *ht = &hpb->timers[i];

 		if (ht->in_use)
 			continue;
 		if (!ht->fsb)
 			continue;
 		if (!ht->bit64)
 			continue;
 		ht->in_use = true;
 		ret = ht;
 		break;
 	}
 	spin_unlock(&hpb->lock);
 	return ret;
 }

 void hpet_put_timer(struct hpet_timer *ht)
 {
 	struct hpet_block *hpb = gbl_hpet;

 	if (!hpb)
 		return;
 	spin_lock(&hpb->lock);
 	ht->in_use = false;
 	spin_unlock(&hpb->lock);
 }

 static void print_hpb_stats(struct hpet_block *hpb)
 {
 	printk("HPET at %p:\n", hpb->base);
 	printk("\tVendor: 0x%x\n", (hpb->cap_id >> 16) & 0xffff);
 	printk("\tPeriod: 0x%08x\n", hpb->period);
 	printk("\t32 bit reach: %d sec\n", hpb->reach32);
 	printk("\tTimers: %d\n", hpb->nr_timers);
 	printk("\tMain counter size: %d\n", hpb->cap_id & (1 << 13) ? 64 : 32);

 	printd("\tcap/id %p\n", hpb->cap_id);
 	printd("\tconfig %p\n", hpet_r64(hpb->base + HPET_CONFIG));
 	printd("\tirqsts %p\n", hpet_r64(hpb->base + HPET_IRQ_STS));

 	for (int i = 0; i < hpb->nr_timers; i++) {
 		printk("\t\tTimer %d: conf %p comp %p, %d bit, %sFSB\n", i,
 		       hpet_r64(hpb->timers[i].base + HPET_TIMER_CONF),
 		       hpet_r64(hpb->timers[i].base + HPET_TIMER_COMP),
 		       hpb->timers[i].bit64 ? 64 : 32,
 		       hpb->timers[i].fsb ? "" : "no ");
 	}
 }

 struct Atable *parsehpet(struct Atable *parent,
                          char *name, uint8_t *raw, size_t rawsize)
 {
 	struct hpet_block *hpb;
 	struct Atable *hpet;
 	uint32_t evt_blk_id;

 	/* Only dealing with one block of these. */
 	if (gbl_hpet) {
 		printk("Found another HPET, skipping!\n");
 		return NULL;
 	}

 	/* Do we want to keep this table around?  if so, we can use newtable,
 	 * which allocs an Atable and puts it on a global stailq.  then we
 	 * return that pointer, not as an addr, but as a signal to parse code
 	 * about whether or not it is safe to unmap (which we don't do anymore).
 	 */
 	hpet = mkatable(parent, HPET, "HPET", raw, rawsize, 0);
 	assert(hpet);
 	printk("HPET table detected at %p, for %d bytes\n", raw, rawsize);

 	evt_blk_id = l32get(raw + 36);

 	hpb = kzmalloc(sizeof(*hpb), MEM_WAIT);
 	spinlock_init(&hpb->lock);

 	hpb->base = vmap_pmem_nocache(l64get(raw + 44), HPET_BLOCK_LEN);
 	if (!hpb->base) {
 		printk("HPET failed to get an iomapping, aborting\n");
 		kfree(hpb);
 		kfree(hpet);
 		return NULL;
 	}

 	hpb->cap_id = hpet_r64(hpb->base + HPET_CAP_ID);
 	if (evt_blk_id != (hpb->cap_id & 0xffffffff)) {
 		printk("HPET ACPI mismatch: ACPI: %p HPET: %p\n", evt_blk_id,
 		       hpb->cap_id);
 	}
 	hpb->nr_timers = ((hpb->cap_id >> 8) & 0xf) + 1;

 	/* femtoseconds (10E-15) per tick.
 	 * e.g. 69 ns per tick.
 	 * freq is just 10^15 / period: 14.318 MHz
 	 * reach of 32 bit counter:
 	 * period fs/tick * 1sec/10^15fs * 2^32tick/wrap ~= 299 seconds */
 	hpb->period = hpb->cap_id >> 32;
 	hpb->nsec_per_tick = hpb->period / 1000000;
 	hpb->reach32 = hpb->period * (1ULL << 32) / 1000000000000000ULL;

 	for (int i = 0; i < hpb->nr_timers; i++) {
 		struct hpet_timer *ht = &hpb->timers[i];
 		uint64_t conf;

 		ht->base = hpb->base + 0x100 + 0x20 * i;
 		ht->hpb = hpb;
 		conf = hpet_r64(ht->base + HPET_TIMER_CONF);
 		ht->bit64 = conf & HPET_TN_SIZE_CAP;
 		ht->fsb = conf & HPET_TN_FSB_INT_DEL_CAP;
 		hpet_timer_disable(ht);
 	}

 	/* No interest in legacy mode. */
 	hpet_w64(hpb->base + HPET_CONFIG,
 		 hpet_r64(hpb->base + HPET_CONFIG) & HPET_CONF_LEG_RT_CNF);
 	/* All timers are off currently */
 	hpet_w64(hpb->base + HPET_CONFIG,
 		 hpet_r64(hpb->base + HPET_CONFIG) | HPET_CONF_ENABLE_CNF);

 	gbl_hpet = hpb;

 	return finatable_nochildren(hpet);
 }

 void cmos_dumping_ground(void)
 {
 	uint8_t cmos_b;

 	/* this stuff tries to turn off various cmos / RTC timer bits.  keeping
 	 * around if we need to disable the RTC alarm.  note that the HPET
 	 * replaces the RTC periodic function (where available), and in those
 	 * cases the RTC alarm function is implemented with SMM. */
 	outb(0x70, 0xb);
 	cmos_b = inb(0x71);
 	printk("cmos b 0x%02x\n", cmos_b);

 	cmos_b &= ~((1 << 5) | (1 << 6));
 	outb(0x70, 0xb);
 	outb(0x71, cmos_b);

 	outb(0x70, 0xb);
 	cmos_b = inb(0x71);
 	printk("cmos b 0x%02x\n", cmos_b);
 }
	/* Copyright (c) 2020 Google Inc
	* Copyright (c) 2014 The Regents of the University of California
	* Barret Rhoden <brho@cs.berkeley.edu>
	* See LICENSE for details.
	*
	* HPET nonsense */

	#include <string.h>
	#include <stdio.h>
	#include <assert.h>
	#include <endian.h>
	#include <pmap.h>
	#include <acpi.h>
	#include <kmalloc.h>

	#include "hpet.h"

	#define HPET_BLOCK_LEN 1024

	#define HPET_CAP_ID 0x00
	#define HPET_CONFIG 0x10
	#define HPET_IRQ_STS 0x20
	#define HPET_MAIN_COUNTER 0xf0

	#define HPET_CONF_LEG_RT_CNF (1 << 1)
	#define HPET_CONF_ENABLE_CNF (1 << 0)

	#define HPET_TIMER_CONF 0x00
	#define HPET_TIMER_COMP 0x08
	#define HPET_TIMER_FSB 0x10

	#define HPET_TN_INT_TYPE_CNF (1 << 1)
	#define HPET_TN_INT_ENB_CNF (1 << 2)
	#define HPET_TN_TYPE_CNF (1 << 3)
	#define HPET_TN_PER_INT_CAP (1 << 4)
	#define HPET_TN_SIZE_CAP (1 << 5)
	#define HPET_TN_VAL_SET_CNF (1 << 6)
	#define HPET_TN_32MODE_CNF (1 << 8)
	#define HPET_TN_INT_ROUTE_CNF (0x1f << 9)
	#define HPET_TN_FSB_EN_CNF (1 << 14)
	#define HPET_TN_FSB_INT_DEL_CAP (1 << 15)
	#define HPET_TN_INT_ROUTE_CAP (0xffffffffULL << 32)

	static struct hpet_block *gbl_hpet;

	/* The HPET likes 64bit mmreg reads and writes. If the arch doesn't support
	* them, then things are a little trickier. Probably just replace these with
	* mm64 ops, and quit supporting 32 bit. */
	static inline void hpet_w64(uintptr_t reg, uint64_t val)
	{
	((volatile uint64_t)reg) = val;
	}

	static inline uint64_t hpet_r64(uintptr_t reg)
	{
	return ((volatile uint64_t)reg);
	}

	void hpet_timer_enable(struct hpet_timer *ht)
	{
	hpet_w64(ht->base + HPET_TIMER_CONF, ht->enable_cmd);
	}

	void hpet_timer_disable(struct hpet_timer *ht)
	{
	hpet_w64(ht->base + HPET_TIMER_CONF, 0);
	}

	/* This only works on 64 bit counters, where we don't have to deal with
	* wrap-around. */
	bool hpet_check_spurious_64(struct hpet_timer *ht)
	{
	return hpet_r64(ht->hpb->base + HPET_MAIN_COUNTER) <
	hpet_r64(ht->base + HPET_TIMER_COMP);
	}

	/* There is no upper addr! But o/w, this is basically MSI. To be fair, we zero
	* out the upper addr in msi.c too. */
	static uint64_t fsb_make_addr(uint8_t dest)
	{
	return 0xfee00000 \| (dest << 12);
	}

	/* dmode: e.g. 000 = fixed, 100 = NMI. Assuming edge triggered */
	static uint64_t fsb_make_data(uint8_t vno, uint8_t dmode)
	{
	return (dmode << 8) \| vno;
	}

	/* This is a very limited HPET timer, primarily used by the watchdog.
	*
	* It's a one-shot (non-periodic), FSB, 64-bit, edge-triggered timer for Core 0
	* with vector vno and delivery mode dmode.
	*
	* Why so specific? Okay, the HPET is a piece of shit, at least on my machine.
	* If you disable the interrupt, and then the time comes where MAIN == COMP, the
	* IRQ will be suppressed, but when you enable later on, the IRQ will fire. No
	* way around it that I can find.
	*
	* One trick is to set the COMP to some time that won't fire, i.e. in the past.
	* However, the 32 bit counters are only about a 5 minute reach. So this trick
	* only works with the 64 bit counter.
	*
	* However, even with that, if the IRQ ever legitimately fires, any time you
	* reenable the timer, it triggers an IRQ.
	*
	* This is all with FSB (which has to be edge triggered) interrupt styles. I
	* tried various combos of "write to the IRQ_STS register", change certain
	* fields in timer CONF, disable the global counter while making changes, etc.
	* All things that aren't in the book, but that might clear whatever internal
	* bit is set.
	*
	* Ultimately, I opted to handle the 'spurious' interrupt in SW, though with a 5
	* minute reach, you can't tell between an old value and a new one. Unless you
	* use a 64 bit counter - then wraparound isn't a concern. If we wanted to do
	* this for a 32 bit counter, we'd need to drastically limit the reach. */
	void hpet_magic_timer_setup(struct hpet_timer *ht, uint8_t vno, uint8_t dmode)
	{
	/* Unlike the other reserved bits in the hpb's registers, the spec says
	* that timer (ht) conf reserved bits should be set to 0.
	*
	* In lieu of screwing around too much, we just set the entire register
	* in one shot. Disabled = 0, enabled = all bits needed. The
	* disastrous behavior mentioned above occurs regardless of the
	* technique used. */
	hpet_timer_disable(ht);

	/* Core 0, fixed, with vno */
	hpet_w64(ht->base + HPET_TIMER_FSB,
	(fsb_make_addr(0) << 32) \| fsb_make_data(vno, dmode));

	ht->enable_cmd = HPET_TN_FSB_EN_CNF \| HPET_TN_INT_ENB_CNF;
	}

	/* Sets the time to fire X ns in the future. No guarantees or sanity checks.
	* If we get delayed setting this, the main counter may pass by our ticks value
	* before we write it, and you'll never get it. */
	void hpet_timer_increment_comparator(struct hpet_timer *ht, uint64_t nsec)
	{
	uint64_t ticks;

	ticks = hpet_r64(ht->hpb->base + HPET_MAIN_COUNTER);
	ticks += nsec / ht->hpb->nsec_per_tick;
	hpet_w64(ht->base + HPET_TIMER_COMP, ticks);
	}

	/* See above. Need 64 bit and FSB */
	struct hpet_timer *hpet_get_magic_timer(void)
	{
	struct hpet_block *hpb = gbl_hpet;
	struct hpet_timer *ret = NULL;

	if (!hpb)
	return NULL;
	spin_lock(&hpb->lock);
	for (int i = 0; i < hpb->nr_timers; i++) {
	struct hpet_timer *ht = &hpb->timers[i];

	if (ht->in_use)
	continue;
	if (!ht->fsb)
	continue;
	if (!ht->bit64)
	continue;
	ht->in_use = true;
	ret = ht;
	break;
	}
	spin_unlock(&hpb->lock);
	return ret;
	}

	void hpet_put_timer(struct hpet_timer *ht)
	{
	struct hpet_block *hpb = gbl_hpet;

	if (!hpb)
	return;
	spin_lock(&hpb->lock);
	ht->in_use = false;
	spin_unlock(&hpb->lock);
	}

	static void print_hpb_stats(struct hpet_block *hpb)
	{
	printk("HPET at %p:\n", hpb->base);
	printk("\tVendor: 0x%x\n", (hpb->cap_id >> 16) & 0xffff);
	printk("\tPeriod: 0x%08x\n", hpb->period);
	printk("\t32 bit reach: %d sec\n", hpb->reach32);
	printk("\tTimers: %d\n", hpb->nr_timers);
	printk("\tMain counter size: %d\n", hpb->cap_id & (1 << 13) ? 64 : 32);

	printd("\tcap/id %p\n", hpb->cap_id);
	printd("\tconfig %p\n", hpet_r64(hpb->base + HPET_CONFIG));
	printd("\tirqsts %p\n", hpet_r64(hpb->base + HPET_IRQ_STS));

	for (int i = 0; i < hpb->nr_timers; i++) {
	printk("\t\tTimer %d: conf %p comp %p, %d bit, %sFSB\n", i,
	hpet_r64(hpb->timers[i].base + HPET_TIMER_CONF),
	hpet_r64(hpb->timers[i].base + HPET_TIMER_COMP),
	hpb->timers[i].bit64 ? 64 : 32,
	hpb->timers[i].fsb ? "" : "no ");
	}
	}

	struct Atable parsehpet(struct Atable parent,
	char name, uint8_t raw, size_t rawsize)
	{
	struct hpet_block *hpb;
	struct Atable *hpet;
	uint32_t evt_blk_id;

	/* Only dealing with one block of these. */
	if (gbl_hpet) {
	printk("Found another HPET, skipping!\n");
	return NULL;
	}

	/* Do we want to keep this table around? if so, we can use newtable,
	* which allocs an Atable and puts it on a global stailq. then we
	* return that pointer, not as an addr, but as a signal to parse code
	* about whether or not it is safe to unmap (which we don't do anymore).
	*/
	hpet = mkatable(parent, HPET, "HPET", raw, rawsize, 0);
	assert(hpet);
	printk("HPET table detected at %p, for %d bytes\n", raw, rawsize);

	evt_blk_id = l32get(raw + 36);

	hpb = kzmalloc(sizeof(*hpb), MEM_WAIT);
	spinlock_init(&hpb->lock);

	hpb->base = vmap_pmem_nocache(l64get(raw + 44), HPET_BLOCK_LEN);
	if (!hpb->base) {
	printk("HPET failed to get an iomapping, aborting\n");
	kfree(hpb);
	kfree(hpet);
	return NULL;
	}

	hpb->cap_id = hpet_r64(hpb->base + HPET_CAP_ID);
	if (evt_blk_id != (hpb->cap_id & 0xffffffff)) {
	printk("HPET ACPI mismatch: ACPI: %p HPET: %p\n", evt_blk_id,
	hpb->cap_id);
	}
	hpb->nr_timers = ((hpb->cap_id >> 8) & 0xf) + 1;

	/* femtoseconds (10E-15) per tick.
	* e.g. 69 ns per tick.
	* freq is just 10^15 / period: 14.318 MHz
	* reach of 32 bit counter:
	* period fs/tick * 1sec/10^15fs * 2^32tick/wrap ~= 299 seconds */
	hpb->period = hpb->cap_id >> 32;
	hpb->nsec_per_tick = hpb->period / 1000000;
	hpb->reach32 = hpb->period * (1ULL << 32) / 1000000000000000ULL;

	for (int i = 0; i < hpb->nr_timers; i++) {
	struct hpet_timer *ht = &hpb->timers[i];
	uint64_t conf;

	ht->base = hpb->base + 0x100 + 0x20 * i;
	ht->hpb = hpb;
	conf = hpet_r64(ht->base + HPET_TIMER_CONF);
	ht->bit64 = conf & HPET_TN_SIZE_CAP;
	ht->fsb = conf & HPET_TN_FSB_INT_DEL_CAP;
	hpet_timer_disable(ht);
	}

	/* No interest in legacy mode. */
	hpet_w64(hpb->base + HPET_CONFIG,
	hpet_r64(hpb->base + HPET_CONFIG) & HPET_CONF_LEG_RT_CNF);
	/* All timers are off currently */
	hpet_w64(hpb->base + HPET_CONFIG,
	hpet_r64(hpb->base + HPET_CONFIG) \| HPET_CONF_ENABLE_CNF);

	gbl_hpet = hpb;

	return finatable_nochildren(hpet);
	}

	void cmos_dumping_ground(void)
	{
	uint8_t cmos_b;

	/* this stuff tries to turn off various cmos / RTC timer bits. keeping
	* around if we need to disable the RTC alarm. note that the HPET
	* replaces the RTC periodic function (where available), and in those
	* cases the RTC alarm function is implemented with SMM. */
	outb(0x70, 0xb);
	cmos_b = inb(0x71);
	printk("cmos b 0x%02x\n", cmos_b);

	cmos_b &= ~((1 << 5) \| (1 << 6));
	outb(0x70, 0xb);
	outb(0x71, cmos_b);

	outb(0x70, 0xb);
	cmos_b = inb(0x71);
	printk("cmos b 0x%02x\n", cmos_b);
	}