apm.c

这个linux源代码是很全面的~基本完整了~使用c编译的~由于时间问题我没有亲自测试~但就算用来做参考资料也是非常好的

/*
 * These are the actual BIOS calls.  Depending on APM_ZERO_SEGS and
 * apm_info.allow_ints, we are being really paranoid here!  Not only
 * are interrupts disabled, but all the segment registers (except SS)
 * are saved and zeroed this means that if the BIOS tries to reference
 * any data without explicitly loading the segment registers, the kernel
 * will fault immediately rather than have some unforeseen circumstances
 * for the rest of the kernel.  And it will be very obvious!  :-) Doing
 * this depends on CS referring to the same physical memory as DS so that
 * DS can be zeroed before the call. Unfortunately, we can't do anything
 * about the stack segment/pointer.  Also, we tell the compiler that
 * everything could change.
 *
 * Also, we KNOW that for the non error case of apm_bios_call, there
 * is no useful data returned in the low order 8 bits of eax.
 */
#define APM_DO_CLI	\
	if (apm_info.allow_ints) \
		__sti(); \
	else \
		__cli();

#ifdef APM_ZERO_SEGS
#	define APM_DECL_SEGS \
		unsigned int saved_fs; unsigned int saved_gs;
#	define APM_DO_SAVE_SEGS \
		savesegment(fs, saved_fs); savesegment(gs, saved_gs)
#	define APM_DO_ZERO_SEGS \
		"pushl %%ds\n\t" \
		"pushl %%es\n\t" \
		"xorl %%edx, %%edx\n\t" \
		"mov %%dx, %%ds\n\t" \
		"mov %%dx, %%es\n\t" \
		"mov %%dx, %%fs\n\t" \
		"mov %%dx, %%gs\n\t"
#	define APM_DO_POP_SEGS \
		"popl %%es\n\t" \
		"popl %%ds\n\t"
#	define APM_DO_RESTORE_SEGS \
		loadsegment(fs, saved_fs); loadsegment(gs, saved_gs)
#else
#	define APM_DECL_SEGS
#	define APM_DO_SAVE_SEGS
#	define APM_DO_ZERO_SEGS
#	define APM_DO_POP_SEGS
#	define APM_DO_RESTORE_SEGS
#endif

/**
 *	apm_bios_call	-	Make an APM BIOS 32bit call
 *	@func: APM function to execute
 *	@ebx_in: EBX register for call entry
 *	@ecx_in: ECX register for call entry
 *	@eax: EAX register return
 *	@ebx: EBX register return
 *	@ecx: ECX register return
 *	@edx: EDX register return
 *	@esi: ESI register return
 *
 *	Make an APM call using the 32bit protected mode interface. The
 *	caller is responsible for knowing if APM BIOS is configured and
 *	enabled. This call can disable interrupts for a long period of
 *	time on some laptops.  The return value is in AH and the carry
 *	flag is loaded into AL.  If there is an error, then the error
 *	code is returned in AH (bits 8-15 of eax) and this function
 *	returns non-zero.
 */
 
static u8 apm_bios_call(u32 func, u32 ebx_in, u32 ecx_in,
	u32 *eax, u32 *ebx, u32 *ecx, u32 *edx, u32 *esi)
{
	APM_DECL_SEGS
	unsigned long	flags;
	unsigned long cpus = apm_save_cpus();
	struct desc_struct	save_desc_40;
	
	__save_flags(flags);
	APM_DO_CLI;
	APM_DO_SAVE_SEGS;
	/*
	 * N.B. We do NOT need a cld after the BIOS call
	 * because we always save and restore the flags.
	 */
	__asm__ __volatile__(APM_DO_ZERO_SEGS
		"pushl %%edi\n\t"
		"pushl %%ebp\n\t"
		"lcall %%cs:" SYMBOL_NAME_STR(apm_bios_entry) "\n\t"
		"setc %%al\n\t"
		"popl %%ebp\n\t"
		"popl %%edi\n\t"
		APM_DO_POP_SEGS
		: "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx),
		  "=S" (*esi)
		: "a" (func), "b" (ebx_in), "c" (ecx_in)
		: "memory", "cc");
	APM_DO_RESTORE_SEGS;
	__restore_flags(flags);
	
	apm_restore_cpus(cpus);
	
	cpu_gdt_table[smp_processor_id()][0x40 / 8] = save_desc_40;
	
	return *eax & 0xff;
}

/**
 *	apm_bios_call_simple	-	make a simple APM BIOS 32bit call
 *	@func: APM function to invoke
 *	@ebx_in: EBX register value for BIOS call
 *	@ecx_in: ECX register value for BIOS call
 *	@eax: EAX register on return from the BIOS call
 *
 *	Make a BIOS call that does only returns one value, or just status.
 *	If there is an error, then the error code is returned in AH
 *	(bits 8-15 of eax) and this function returns non-zero. This is
 *	used for simpler BIOS operations. This call may hold interrupts
 *	off for a long time on some laptops.
 */

static u8 apm_bios_call_simple(u32 func, u32 ebx_in, u32 ecx_in, u32 *eax)
{
	u8		error;
	APM_DECL_SEGS
	unsigned long		flags;
	int			cpu = smp_processor_id();
	struct desc_struct	save_desc_40;
	unsigned long cpus = apm_save_cpus();

	save_desc_40 = cpu_gdt_table[cpu][0x40 / 8];
	cpu_gdt_table[cpu][0x40 / 8] = bad_bios_desc;
	
	__save_flags(flags);
	APM_DO_CLI;
	APM_DO_SAVE_SEGS;
	{
		int	cx, dx, si;

		/*
		 * N.B. We do NOT need a cld after the BIOS call
		 * because we always save and restore the flags.
		 */
		__asm__ __volatile__(APM_DO_ZERO_SEGS
			"pushl %%edi\n\t"
			"pushl %%ebp\n\t"
			"lcall %%cs:" SYMBOL_NAME_STR(apm_bios_entry) "\n\t"
			"setc %%bl\n\t"
			"popl %%ebp\n\t"
			"popl %%edi\n\t"
			APM_DO_POP_SEGS
			: "=a" (*eax), "=b" (error), "=c" (cx), "=d" (dx),
			  "=S" (si)
			: "a" (func), "b" (ebx_in), "c" (ecx_in)
			: "memory", "cc");
	}
	APM_DO_RESTORE_SEGS;
	__restore_flags(flags);

	apm_restore_cpus(cpus);
	
	cpu_gdt_table[smp_processor_id()][0x40 / 8] = save_desc_40;
	
	return error;
}

/**
 *	apm_driver_version	-	APM driver version
 *	@val:	loaded with the APM version on return
 *
 *	Retrieve the APM version supported by the BIOS. This is only
 *	supported for APM 1.1 or higher. An error indicates APM 1.0 is
 *	probably present.
 *
 *	On entry val should point to a value indicating the APM driver
 *	version with the high byte being the major and the low byte the
 *	minor number both in BCD
 *
 *	On return it will hold the BIOS revision supported in the
 *	same format.
 */

static int __init apm_driver_version(u_short *val)
{
	u32	eax;

	if (apm_bios_call_simple(APM_FUNC_VERSION, 0, *val, &eax))
		return (eax >> 8) & 0xff;
	*val = eax;
	return APM_SUCCESS;
}

/**
 *	apm_get_event	-	get an APM event from the BIOS
 *	@event: pointer to the event
 *	@info: point to the event information
 *
 *	The APM BIOS provides a polled information for event
 *	reporting. The BIOS expects to be polled at least every second
 *	when events are pending. When a message is found the caller should
 *	poll until no more messages are present.  However, this causes
 *	problems on some laptops where a suspend event notification is
 *	not cleared until it is acknowledged.
 *
 *	Additional information is returned in the info pointer, providing
 *	that APM 1.2 is in use. If no messges are pending the value 0x80
 *	is returned (No power management events pending).
 */
 
static int apm_get_event(apm_event_t *event, apm_eventinfo_t *info)
{
	u32	eax;
	u32	ebx;
	u32	ecx;
	u32	dummy;

	if (apm_bios_call(APM_FUNC_GET_EVENT, 0, 0, &eax, &ebx, &ecx,
			&dummy, &dummy))
		return (eax >> 8) & 0xff;
	*event = ebx;
	if (apm_info.connection_version < 0x0102)
		*info = ~0; /* indicate info not valid */
	else
		*info = ecx;
	return APM_SUCCESS;
}

/**
 *	set_power_state	-	set the power management state
 *	@what: which items to transition
 *	@state: state to transition to
 *
 *	Request an APM change of state for one or more system devices. The
 *	processor state must be transitioned last of all. what holds the
 *	class of device in the upper byte and the device number (0xFF for
 *	all) for the object to be transitioned.
 *
 *	The state holds the state to transition to, which may in fact
 *	be an acceptance of a BIOS requested state change.
 */
 
static int set_power_state(u_short what, u_short state)
{
	u32	eax;

	if (apm_bios_call_simple(APM_FUNC_SET_STATE, what, state, &eax))
		return (eax >> 8) & 0xff;
	return APM_SUCCESS;
}

/**
 *	set_system_power_state - set system wide power state
 *	@state: which state to enter
 *
 *	Transition the entire system into a new APM power state.
 */
 
static int set_system_power_state(u_short state)
{
	return set_power_state(APM_DEVICE_ALL, state);
}

/**
 *	apm_do_idle	-	perform power saving
 *
 *	This function notifies the BIOS that the processor is (in the view
 *	of the OS) idle. It returns -1 in the event that the BIOS refuses
 *	to handle the idle request. On a success the function returns 1
 *	if the BIOS did clock slowing or 0 otherwise.
 */
 
static int apm_do_idle(void)
{
	u32	eax;

	if (apm_bios_call_simple(APM_FUNC_IDLE, 0, 0, &eax)) {
		static unsigned long t;

		/* This always fails on some SMP boards running UP kernels.
		 * Only report the failure the first 5 times.
		 */
		if (++t < 5) {
			printk(KERN_DEBUG "apm_do_idle failed (%d)\n",
					(eax >> 8) & 0xff);
		}
		return -1;
	}
	clock_slowed = (apm_info.bios.flags & APM_IDLE_SLOWS_CLOCK) != 0;
	return clock_slowed;
}

/**
 *	apm_do_busy	-	inform the BIOS the CPU is busy
 *
 *	Request that the BIOS brings the CPU back to full performance. 
 */
 
static void apm_do_busy(void)
{
	u32	dummy;

	if (clock_slowed || ALWAYS_CALL_BUSY) {
		(void) apm_bios_call_simple(APM_FUNC_BUSY, 0, 0, &dummy);
		clock_slowed = 0;
	}
}

/*
 * If no process has really been interested in
 * the CPU for some time, we want to call BIOS
 * power management - we probably want
 * to conserve power.
 */
#define IDLE_CALC_LIMIT   (HZ * 100)
#define IDLE_LEAKY_MAX    16

static void (*original_pm_idle)(void);

extern void default_idle(void);

/**
 * apm_cpu_idle		-	cpu idling for APM capable Linux
 *
 * This is the idling function the kernel executes when APM is available. It 
 * tries to do BIOS powermanagement based on the average system idle time.
 * Furthermore it calls the system default idle routine.
 */

static void apm_cpu_idle(void)
{
	static int use_apm_idle; /* = 0 */
	static unsigned int last_jiffies; /* = 0 */
	static unsigned int last_stime; /* = 0 */

	int apm_idle_done = 0;
	unsigned int jiffies_since_last_check = jiffies - last_jiffies;
	unsigned int bucket;

recalc:
	if (jiffies_since_last_check > IDLE_CALC_LIMIT) {
		use_apm_idle = 0;
		last_jiffies = jiffies;
		last_stime = current->times.tms_stime;
	} else if (jiffies_since_last_check > idle_period) {
		unsigned int idle_percentage;

		idle_percentage = current->times.tms_stime - last_stime;
		idle_percentage *= 100;
		idle_percentage /= jiffies_since_last_check;
		use_apm_idle = (idle_percentage > idle_threshold);
		if (apm_info.forbid_idle)
			use_apm_idle = 0;
		last_jiffies = jiffies;
		last_stime = current->times.tms_stime;
	}

	bucket = IDLE_LEAKY_MAX;

	while (!current->need_resched) {
		if (use_apm_idle) {
			unsigned int t;

			t = jiffies;
			switch (apm_do_idle()) {
			case 0: apm_idle_done = 1;
				if (t != jiffies) {
					if (bucket) {
						bucket = IDLE_LEAKY_MAX;
						continue;
					}
				} else if (bucket) {
					bucket--;
					continue;
				}
				break;
			case 1: apm_idle_done = 1;
				break;
			default: /* BIOS refused */
				break;
			}
		}
		if (original_pm_idle)
			original_pm_idle();
		else
			default_idle();
		jiffies_since_last_check = jiffies - last_jiffies;
		if (jiffies_since_last_check > idle_period)
			goto recalc;
	}

	if (apm_idle_done)
		apm_do_busy();
}

/**
 *	apm_power_off	-	ask the BIOS to power off
 *
 *	Handle the power off sequence. This is the one piece of code we
 *	will execute even on SMP machines. In order to deal with BIOS
 *	bugs we support real mode APM BIOS power off calls. We also make
 *	the SMP call on CPU0 as some systems will only honour this call
 *	on their first cpu.
 */
 
static void apm_power_off(void)
{
	unsigned char	po_bios_call[] = {
		0xb8, 0x00, 0x10,	/* movw  $0x1000,ax  */
		0x8e, 0xd0,		/* movw  ax,ss       */
		0xbc, 0x00, 0xf0,	/* movw  $0xf000,sp  */
		0xb8, 0x07, 0x53,	/* movw  $0x5307,ax  */
		0xbb, 0x01, 0x00,	/* movw  $0x0001,bx  */
		0xb9, 0x03, 0x00,	/* movw  $0x0003,cx  */
		0xcd, 0x15		/* int   $0x15       */
	};

	/*
	 * This may be called on an SMP machine.
	 */
	if (apm_info.realmode_power_off)
	{
		(void)apm_save_cpus();
		machine_real_restart(po_bios_call, sizeof(po_bios_call));
		/* Never returns */
	}
	else
		(void) set_system_power_state(APM_STATE_OFF);
}

/**
 * handle_poweroff	-	sysrq callback for power down
 * @key: key pressed (unused)
 * @pt_regs: register state (unused)
 * @kbd: keyboard state (unused)
 * @tty: tty involved (unused)
 *
 * When the user hits Sys-Rq o to power down the machine this is the
 * callback we use.
 */

void handle_poweroff (int key, struct pt_regs *pt_regs,
		struct kbd_struct *kbd, struct tty_struct *tty) {
        apm_power_off();
}

struct sysrq_key_op	sysrq_poweroff_op = {
	handler:        handle_poweroff,
	help_msg:       "Off",
	action_msg:     "Power Off\n"
};


#ifdef CONFIG_APM_DO_ENABLE

/**
 *	apm_enable_power_management - enable BIOS APM power management
 *	@enable: enable yes/no
 *
 *	Enable or disable the APM BIOS power services. 
 */
 
static int apm_enable_power_management(int enable)
{
	u32	eax;

	if ((enable == 0) && (apm_info.bios.flags & APM_BIOS_DISENGAGED))
		return APM_NOT_ENGAGED;
	if (apm_bios_call_simple(APM_FUNC_ENABLE_PM, APM_DEVICE_BALL,
			enable, &eax))
		return (eax >> 8) & 0xff;
	if (enable)
		apm_info.bios.flags &= ~APM_BIOS_DISABLED;
	else
		apm_info.bios.flags |= APM_BIOS_DISABLED;
	return APM_SUCCESS;
}
#endif

/**
 *	apm_get_power_status	-	get current power state
 *	@status: returned status
 *	@bat: battery info
 *	@life: estimated life
 *
 *	Obtain the current power status from the APM BIOS. We return a
 *	status which gives the rough battery status, and current power
 *	source. The bat value returned give an estimate as a percentage
 *	of life and a status value for the battery. The estimated life
 *	if reported is a lifetime in secodnds/minutes at current powwer
 *	consumption.
 */
 
static int apm_get_power_status(u_short *status, u_short *bat, u_short *life)
{
	u32	eax;
	u32	ebx;
	u32	ecx;
	u32	edx;
	u32	dummy;

	if (apm_info.get_power_status_broken)
		return APM_32_UNSUPPORTED;
	if (apm_bios_call(APM_FUNC_GET_STATUS, APM_DEVICE_ALL, 0,
			&eax, &ebx, &ecx, &edx, &dummy))
		return (eax >> 8) & 0xff;
	*status = ebx;
	*bat = ecx;
	if (apm_info.get_power_status_swabinminutes) {
		*life = swab16((u16)edx);
		*life |= 0x8000;
	} else
		*life = edx;
	return APM_SUCCESS;
}

#if 0
static int apm_get_battery_status(u_short which, u_short *status,
				  u_short *bat, u_short *life, u_short *nbat)
{
	u32	eax;
	u32	ebx;
	u32	ecx;
	u32	edx;
	u32	esi;

	if (apm_info.connection_version < 0x0102) {
		/* pretend we only have one battery. */
		if (which != 1)
			return APM_BAD_DEVICE;
		*nbat = 1;
		return apm_get_power_status(status, bat, life);
	}

	if (apm_bios_call(APM_FUNC_GET_STATUS, (0x8000 | (which)), 0, &eax,
			&ebx, &ecx, &edx, &esi))