apm.c

linux-2.6.15.6

#define NR_APM_EVENT_NAME ARRAY_SIZE(apm_event_name)

typedef struct lookup_t {
	int	key;
	char *	msg;
} lookup_t;

/*
 *	The BIOS returns a set of standard error codes in AX when the
 *	carry flag is set.
 */
 
static const lookup_t error_table[] = {
/* N/A	{ APM_SUCCESS,		"Operation succeeded" }, */
	{ APM_DISABLED,		"Power management disabled" },
	{ APM_CONNECTED,	"Real mode interface already connected" },
	{ APM_NOT_CONNECTED,	"Interface not connected" },
	{ APM_16_CONNECTED,	"16 bit interface already connected" },
/* N/A	{ APM_16_UNSUPPORTED,	"16 bit interface not supported" }, */
	{ APM_32_CONNECTED,	"32 bit interface already connected" },
	{ APM_32_UNSUPPORTED,	"32 bit interface not supported" },
	{ APM_BAD_DEVICE,	"Unrecognized device ID" },
	{ APM_BAD_PARAM,	"Parameter out of range" },
	{ APM_NOT_ENGAGED,	"Interface not engaged" },
	{ APM_BAD_FUNCTION,     "Function not supported" },
	{ APM_RESUME_DISABLED,	"Resume timer disabled" },
	{ APM_BAD_STATE,	"Unable to enter requested state" },
/* N/A	{ APM_NO_EVENTS,	"No events pending" }, */
	{ APM_NO_ERROR,		"BIOS did not set a return code" },
	{ APM_NOT_PRESENT,	"No APM present" }
};
#define ERROR_COUNT	ARRAY_SIZE(error_table)

/**
 *	apm_error	-	display an APM error
 *	@str: information string
 *	@err: APM BIOS return code
 *
 *	Write a meaningful log entry to the kernel log in the event of
 *	an APM error.
 */
 
static void apm_error(char *str, int err)
{
	int	i;

	for (i = 0; i < ERROR_COUNT; i++)
		if (error_table[i].key == err) break;
	if (i < ERROR_COUNT)
		printk(KERN_NOTICE "apm: %s: %s\n", str, error_table[i].msg);
	else
		printk(KERN_NOTICE "apm: %s: unknown error code %#2.2x\n",
			str, err);
}

/*
 * Lock APM functionality to physical CPU 0
 */
 
#ifdef CONFIG_SMP

static cpumask_t apm_save_cpus(void)
{
	cpumask_t x = current->cpus_allowed;
	/* Some bioses don't like being called from CPU != 0 */
	set_cpus_allowed(current, cpumask_of_cpu(0));
	BUG_ON(smp_processor_id() != 0);
	return x;
}

static inline void apm_restore_cpus(cpumask_t mask)
{
	set_cpus_allowed(current, mask);
}

#else

/*
 *	No CPU lockdown needed on a uniprocessor
 */
 
#define apm_save_cpus()		(current->cpus_allowed)
#define apm_restore_cpus(x)	(void)(x)

#endif

/*
 * 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) \
		local_irq_enable(); \
	else \
		local_irq_disable();

#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_RESTORE_SEGS \
		loadsegment(fs, saved_fs); loadsegment(gs, saved_gs)
#else
#	define APM_DECL_SEGS
#	define APM_DO_SAVE_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;
	cpumask_t		cpus;
	int			cpu;
	struct desc_struct	save_desc_40;
	struct desc_struct	*gdt;

	cpus = apm_save_cpus();
	
	cpu = get_cpu();
	gdt = get_cpu_gdt_table(cpu);
	save_desc_40 = gdt[0x40 / 8];
	gdt[0x40 / 8] = bad_bios_desc;

	local_save_flags(flags);
	APM_DO_CLI;
	APM_DO_SAVE_SEGS;
	apm_bios_call_asm(func, ebx_in, ecx_in, eax, ebx, ecx, edx, esi);
	APM_DO_RESTORE_SEGS;
	local_irq_restore(flags);
	gdt[0x40 / 8] = save_desc_40;
	put_cpu();
	apm_restore_cpus(cpus);
	
	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;
	cpumask_t		cpus;
	int			cpu;
	struct desc_struct	save_desc_40;
	struct desc_struct	*gdt;

	cpus = apm_save_cpus();
	
	cpu = get_cpu();
	gdt = get_cpu_gdt_table(cpu);
	save_desc_40 = gdt[0x40 / 8];
	gdt[0x40 / 8] = bad_bios_desc;

	local_save_flags(flags);
	APM_DO_CLI;
	APM_DO_SAVE_SEGS;
	error = apm_bios_call_simple_asm(func, ebx_in, ecx_in, eax);
	APM_DO_RESTORE_SEGS;
	local_irq_restore(flags);
	gdt[0x40 / 8] = save_desc_40;
	put_cpu();
	apm_restore_cpus(cpus);
	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 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;
	u8	ret = 0;
	int	idled = 0;
	int	polling;

	polling = test_thread_flag(TIF_POLLING_NRFLAG);
	if (polling) {
		clear_thread_flag(TIF_POLLING_NRFLAG);
		smp_mb__after_clear_bit();
	}
	if (!need_resched()) {
		idled = 1;
		ret = apm_bios_call_simple(APM_FUNC_IDLE, 0, 0, &eax);
	}
	if (polling)
		set_thread_flag(TIF_POLLING_NRFLAG);

	if (!idled)
		return 0;

	if (ret) {
		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);
			t = jiffies;
		}
		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->stime;
	} else if (jiffies_since_last_check > idle_period) {
		unsigned int idle_percentage;

		idle_percentage = current->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->stime;
	}

	bucket = IDLE_LEAKY_MAX;

	while (!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)