Add some basic resume trace facilities

  RODATA

  . = ALIGN(4);

  __tracedata_start = .;

  .tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) {

	*(.tracedata)

  }

  __tracedata_end = .;

  /* writeable */

  .data : AT(ADDR(.data) - LOAD_OFFSET) {	/* Data */

	*(.data)

obj-y			:= shutdown.o

obj-$(CONFIG_PM)	+= main.o suspend.o resume.o runtime.o sysfs.o

obj-$(CONFIG_PM_TRACE)	+= trace.o

ifeq ($(CONFIG_DEBUG_DRIVER),y)

EXTRA_CFLAGS += -DDEBUG

/*

 * drivers/base/power/trace.c

 *

 * Copyright (C) 2006 Linus Torvalds

 *

 * Trace facility for suspend/resume problems, when none of the

 * devices may be working.

 */

#include <linux/resume-trace.h>

#include <linux/rtc.h>

#include <asm/rtc.h>

#include "power.h"

/*

 * Horrid, horrid, horrid.

 *

 * It turns out that the _only_ piece of hardware that actually

 * keeps its value across a hard boot (and, more importantly, the

 * POST init sequence) is literally the realtime clock.

 *

 * Never mind that an RTC chip has 114 bytes (and often a whole

 * other bank of an additional 128 bytes) of nice SRAM that is

 * _designed_ to keep data - the POST will clear it. So we literally

 * can just use the few bytes of actual time data, which means that

 * we're really limited.

 *

 * It means, for example, that we can't use the seconds at all

 * (since the time between the hang and the boot might be more

 * than a minute), and we'd better not depend on the low bits of

 * the minutes either.

 *

 * There are the wday fields etc, but I wouldn't guarantee those

 * are dependable either. And if the date isn't valid, either the

 * hw or POST will do strange things.

 *

 * So we're left with:

 *  - year: 0-99

 *  - month: 0-11

 *  - day-of-month: 1-28

 *  - hour: 0-23

 *  - min: (0-30)*2

 *

 * Giving us a total range of 0-16128000 (0xf61800), ie less

 * than 24 bits of actual data we can save across reboots.

 *

 * And if your box can't boot in less than three minutes,

 * you're screwed.

 *

 * Now, almost 24 bits of data is pitifully small, so we need

 * to be pretty dense if we want to use it for anything nice.

 * What we do is that instead of saving off nice readable info,

 * we save off _hashes_ of information that we can hopefully

 * regenerate after the reboot.

 *

 * In particular, this means that we might be unlucky, and hit

 * a case where we have a hash collision, and we end up not

 * being able to tell for certain exactly which case happened.

 * But that's hopefully unlikely.

 *

 * What we do is to take the bits we can fit, and split them

 * into three parts (16*997*1009 = 16095568), and use the values

 * for:

 *  - 0-15: user-settable

 *  - 0-996: file + line number

 *  - 0-1008: device

 */

#define USERHASH (16)

#define FILEHASH (997)

#define DEVHASH (1009)

#define DEVSEED (7919)

static unsigned int dev_hash_value;

static int set_magic_time(unsigned int user, unsigned int file, unsigned int device)

{

	unsigned int n = user + USERHASH*(file + FILEHASH*device);

	// June 7th, 2006

	static struct rtc_time time = {

		.tm_sec = 0,

		.tm_min = 0,

		.tm_hour = 0,

		.tm_mday = 7,

		.tm_mon = 5,	// June - counting from zero

		.tm_year = 106,

		.tm_wday = 3,

		.tm_yday = 160,

		.tm_isdst = 1

	};

	time.tm_year = (n % 100);

	n /= 100;

	time.tm_mon = (n % 12);

	n /= 12;

	time.tm_mday = (n % 28) + 1;

	n /= 28;

	time.tm_hour = (n % 24);

	n /= 24;

	time.tm_min = (n % 20) * 3;

	n /= 20;

	set_rtc_time(&time);

	return n ? -1 : 0;

}

static unsigned int read_magic_time(void)

{

	struct rtc_time time;

	unsigned int val;

	get_rtc_time(&time);

	printk("Time: %2d:%02d:%02d  Date: %02d/%02d/%02d\n",

		time.tm_hour, time.tm_min, time.tm_sec,

		time.tm_mon, time.tm_mday, time.tm_year);

	val = time.tm_year;				/* 100 years */

	if (val > 100)

		val -= 100;

	val += time.tm_mon * 100;			/* 12 months */

	val += (time.tm_mday-1) * 100 * 12;		/* 28 month-days */

	val += time.tm_hour * 100 * 12 * 28;		/* 24 hours */

	val += (time.tm_min / 3) * 100 * 12 * 28 * 24;	/* 20 3-minute intervals */

	return val;

}

/*

 * This is just the sdbm hash function with a user-supplied

 * seed and final size parameter.

 */

static unsigned int hash_string(unsigned int seed, const char *data, unsigned int mod)

{

	unsigned char c;

	while ((c = *data++) != 0) {

		seed = (seed << 16) + (seed << 6) - seed + c;

	}

	return seed % mod;

}

void set_trace_device(struct device *dev)

{

	dev_hash_value = hash_string(DEVSEED, dev->bus_id, DEVHASH);

}

/*

 * We could just take the "tracedata" index into the .tracedata

 * section instead. Generating a hash of the data gives us a

 * chance to work across kernel versions, and perhaps more

 * importantly it also gives us valid/invalid check (ie we will

 * likely not give totally bogus reports - if the hash matches,

 * it's not any guarantee, but it's a high _likelihood_ that

 * the match is valid).

 */

void generate_resume_trace(void *tracedata, unsigned int user)

{

	unsigned short lineno = *(unsigned short *)tracedata;

	const char *file = *(const char **)(tracedata + 2);

	unsigned int user_hash_value, file_hash_value;

	user_hash_value = user % USERHASH;

	file_hash_value = hash_string(lineno, file, FILEHASH);

	set_magic_time(user_hash_value, file_hash_value, dev_hash_value);

}

extern char __tracedata_start, __tracedata_end;

static int show_file_hash(unsigned int value)

{

	int match;

	char *tracedata;

	match = 0;

	for (tracedata = &__tracedata_start ; tracedata < &__tracedata_end ; tracedata += 6) {

		unsigned short lineno = *(unsigned short *)tracedata;

		const char *file = *(const char **)(tracedata + 2);

		unsigned int hash = hash_string(lineno, file, FILEHASH);

		if (hash != value)

			continue;

		printk("  hash matches %s:%u\n", file, lineno);

		match++;

	}

	return match;

}

static int show_dev_hash(unsigned int value)

{

	int match = 0;

	struct list_head * entry = dpm_active.prev;

	while (entry != &dpm_active) {

		struct device * dev = to_device(entry);

		unsigned int hash = hash_string(DEVSEED, dev->bus_id, DEVHASH);

		if (hash == value) {

			printk("  hash matches device %s\n", dev->bus_id);

			match++;

		}

		entry = entry->prev;

	}

	return match;

}

static unsigned int hash_value_early_read;

static int early_resume_init(void)

{

	hash_value_early_read = read_magic_time();

	return 0;

}

static int late_resume_init(void)

{

	unsigned int val = hash_value_early_read;

	unsigned int user, file, dev;

	user = val % USERHASH;

	val = val / USERHASH;

	file = val % FILEHASH;

	val = val / FILEHASH;

	dev = val /* % DEVHASH */;

	printk("  Magic number: %d:%d:%d\n", user, file, dev);

	show_file_hash(file);

	show_dev_hash(dev);

	return 0;

}

core_initcall(early_resume_init);

late_initcall(late_resume_init);

/* Set the current date and time in the real time clock. */

static inline int set_rtc_time(struct rtc_time *time)

{

	unsigned long flags;

	unsigned char mon, day, hrs, min, sec;

	unsigned char save_control, save_freq_select;

	unsigned int yrs;

	if (yrs > 255)	/* They are unsigned */

		return -EINVAL;

	spin_lock_irq(&rtc_lock);

	spin_lock_irqsave(&rtc_lock, flags);

#ifdef CONFIG_MACH_DECSTATION

	real_yrs = yrs;

	leap_yr = ((!((yrs + 1900) % 4) && ((yrs + 1900) % 100)) ||

	 * whether the chip is in binary mode or not.

	 */

	if (yrs > 169) {

		spin_unlock_irq(&rtc_lock);

		spin_unlock_irqrestore(&rtc_lock, flags);

		return -EINVAL;

	}

	CMOS_WRITE(save_control, RTC_CONTROL);

	CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);

	spin_unlock_irq(&rtc_lock);

	spin_unlock_irqrestore(&rtc_lock, flags);

	return 0;

}

#ifndef RESUME_TRACE_H

#define RESUME_TRACE_H

#ifdef CONFIG_PM_TRACE

struct device;

extern void set_trace_device(struct device *);

extern void generate_resume_trace(void *tracedata, unsigned int user);

#define TRACE_DEVICE(dev) set_trace_device(dev)

#define TRACE_RESUME(user) do {				\

	void *tracedata;				\

	asm volatile("movl $1f,%0\n"			\

		".section .tracedata,\"a\"\n"		\

		"1:\t.word %c1\n"			\

		"\t.long %c2\n"				\

		".previous"				\

		:"=r" (tracedata)			\

		: "i" (__LINE__), "i" (__FILE__));	\

	generate_resume_trace(tracedata, user);		\

} while (0)

#else

#define TRACE_DEVICE(dev) do { } while (0)

#define TRACE_RESUME(dev) do { } while (0)

#endif

#endif