prpower.c

MIZI Research, Inc.发布的嵌入式Linux内核源码

 *
 * PARAMETERS:
 *
 * RETURN:	
 *
 * DESCRIPTION: Sets the default Cx state policy (OS idle handler).  Our
 *              scheme is to promote quickly to C2 but more conservatively
 *              to C3.  We're favoring C2 for its characteristics of low
 *              latency (quick response), good power savings, and ability
 *              to allow bus mastering activity.
 *
 *              Note that Cx state policy is completely customizable, with
 *              the goal of having heuristics to alter policy dynamically.
 *
 ****************************************************************************/

acpi_status
pr_power_set_default_policy (
	PR_CONTEXT                 *processor)
{
	FUNCTION_TRACE("pr_power_set_default_policy");

	if (!processor) {
		return_ACPI_STATUS(AE_BAD_PARAMETER);
	}

	/*
	 * Busy Metric:
	 * ------------
	 * Used to determine when the OS has been busy and thus when
	 * policy should return to using the default Cx state (e.g. C1).
	 * On Linux we use the number of jiffies (scheduler quantums)
	 * that transpire between calls to the idle handler.
	 *
	 * TBD: Linux-specific.
	 */
	processor->power.busy_metric = 2;

	/*
	 * C1:
	 * ---
	 * C1 serves as our default state.  It must be valid.
	 */
	if (processor->power.state[PR_C1].is_valid) {
		processor->power.active_state =
			processor->power.default_state = PR_C1;
	}
	else {
		processor->power.active_state =
			processor->power.default_state = PR_C0;
		return_ACPI_STATUS(AE_OK);
	}

	/*
	 * C2:
	 * ---
	 * Set default C1 promotion and C2 demotion policies.
	 */
	if (processor->power.state[PR_C2].is_valid) {
		/*
		 * Promote from C1 to C2 anytime we're asleep in C1 for
		 * longer than two times the C2 latency (to amortize cost
		 * of transition).  Demote from C2 to C1 anytime we're
		 * asleep in C2 for less than this time.
		 */
		processor->power.state[PR_C1].promotion.count_threshold = 10;
		processor->power.state[PR_C1].promotion.time_threshold =
			2 * processor->power.state[PR_C2].latency;
		processor->power.state[PR_C1].promotion.target_state = PR_C2;

		processor->power.state[PR_C2].demotion.count_threshold = 1;
		processor->power.state[PR_C2].demotion.time_threshold =
			2 * processor->power.state[PR_C2].latency;
		processor->power.state[PR_C2].demotion.target_state = PR_C1;
	}

	/*
	 * C3:
	 * ---
	 * Set default C2 promotion and C3 demotion policies.
	 */
	if ((processor->power.state[PR_C2].is_valid) &&
		(processor->power.state[PR_C3].is_valid)) {
		/*
		 * Promote from C2 to C3 after 4 cycles of no bus
		 * mastering activity (while maintaining sleep time
		 * criteria).  Demote immediately on a short or
		 * whenever bus mastering activity occurs.
		 */
		processor->power.state[PR_C2].promotion.count_threshold = 1;
		processor->power.state[PR_C2].promotion.time_threshold =
			2 * processor->power.state[PR_C3].latency;
		processor->power.state[PR_C2].promotion.bm_threshold =
			0x0000000F;
		processor->power.state[PR_C2].promotion.target_state =
			PR_C3;

		processor->power.state[PR_C3].demotion.count_threshold = 1;
		processor->power.state[PR_C3].demotion.time_threshold =
			2 * processor->power.state[PR_C3].latency;
		processor->power.state[PR_C3].demotion.bm_threshold =
			0x0000000F;
		processor->power.state[PR_C3].demotion.target_state =
			PR_C2;
	}

	return_ACPI_STATUS(AE_OK);
}

/*****************************************************************************
 *
 * FUNCTION:    pr_power_add_device
 *
 * PARAMETERS:  <none>
 *
 * RETURN:
 *
 * DESCRIPTION:
 *
 ****************************************************************************/

/*
 * TBD: 1. PROC_C1 support.
 *      2. Symmetric Cx state support (different Cx states supported
 *         by different CPUs results in lowest common denominator).
 */

acpi_status
pr_power_add_device (
	PR_CONTEXT                 *processor)
{
	FUNCTION_TRACE("pr_power_add_device");

	if (!processor) {
		return_ACPI_STATUS(AE_BAD_PARAMETER);
	}

	/*
	 * State Count:
	 * ------------
	 * Fixed at four (C0-C3).  We use is_valid to determine whether or
	 * not a state actually gets used.
	 */
	processor->power.state_count = PR_MAX_POWER_STATES;

	/*
	 * C0:
	 * ---
	 * C0 exists only as filler in our array. (Let's assume its valid!)
	 */
	processor->power.state[PR_C0].is_valid = TRUE;

	/*
	 * C1:
	 * ---
	 * ACPI states that C1 must be supported by all processors
	 * with a latency so small that it can be ignored.
	 *
	 * TBD: What about PROC_C1 support?
	 */
	processor->power.state[PR_C1].is_valid = TRUE;

	/*
	 * C2:
	 * ---
	 * We're only supporting C2 on UP systems with latencies <= 100us.
	 *
	 * TBD: Support for C2 on MP (P_LVL2_UP) -- I'm taking the
	 *      conservative approach for now.
	 */
	processor->power.state[PR_C2].latency = acpi_fadt.plvl2_lat;

#ifdef CONFIG_SMP
	if (smp_num_cpus == 1) {
#endif /*CONFIG_SMP*/
		if (acpi_fadt.plvl2_lat <= PR_MAX_C2_LATENCY) {
			processor->power.state[PR_C2].is_valid = TRUE;
			processor->power.p_lvl2 = processor->pblk.address + 4;
		}
#ifdef CONFIG_SMP
	}
#endif /*CONFIG_SMP*/


	/*
	 * C3:
	 * ---
	 * We're only supporting C3 on UP systems with latencies <= 1000us,
	 * and that include the ability to disable bus mastering while in
	 * C3 (ARB_DIS) but allows bus mastering requests to wake the system
	 * from C3 (BM_RLD).  Note his method of maintaining cache coherency
	 * (disabling of bus mastering) cannot be used on SMP systems, and
	 * flushing caches (e.g. WBINVD) is simply too costly at this time.
	 *
	 * TBD: Support for C3 on MP -- I'm taking the conservative
	 *      approach for now.
	 */
	processor->power.state[PR_C3].latency = acpi_fadt.plvl3_lat;

#ifdef CONFIG_SMP
	if (smp_num_cpus == 1) {
#endif /*CONFIG_SMP*/
		if ((acpi_fadt.plvl3_lat <= PR_MAX_C3_LATENCY) && bm_control) {
			processor->power.state[PR_C3].is_valid = TRUE;
			processor->power.p_lvl3 = processor->pblk.address + 5;
		}
#ifdef CONFIG_SMP
	}
#endif /*CONFIG_SMP*/

	/*
	 * Set Default Policy:
	 * -------------------
	 * Now that we know which state are supported, set the default
	 * policy.  Note that this policy can be changed dynamically
	 * (e.g. encourage deeper sleeps to conserve battery life when
	 * not on AC).
	 */
	pr_power_set_default_policy(processor);

	/*
	 * Save Processor Context:
	 * -----------------------
	 * TBD: Enhance Linux idle handler to take processor context
	 *      parameter.
	 */
	processor_list[processor->uid] = processor;

	return_ACPI_STATUS(AE_OK);
}


/****************************************************************************
 *
 * FUNCTION:    pr_power_remove_device
 *
 * PARAMETERS:
 *
 * RETURN:	
 *
 * DESCRIPTION:
 *
 ****************************************************************************/

acpi_status
pr_power_remove_device (
	PR_CONTEXT              *processor)
{
	acpi_status             status = AE_OK;

	FUNCTION_TRACE("pr_power_remove_device");

	if (!processor) {
		return_ACPI_STATUS(AE_BAD_PARAMETER);
	}

	MEMSET(&(processor->power), 0, sizeof(PR_POWER));

	processor_list[processor->uid] = NULL;

	return_ACPI_STATUS(status);
}


/****************************************************************************
 *
 * FUNCTION:    pr_power_initialize
 *
 * PARAMETERS:  <none>
 *
 * RETURN:
 *
 * DESCRIPTION:
 *
 ****************************************************************************/

acpi_status
pr_power_initialize (void)
{
	u32			i = 0;

	FUNCTION_TRACE("pr_power_initialize");

	/* TBD: Linux-specific. */
	for (i=0; i<NR_CPUS; i++) {
		processor_list[i] = NULL;
	}

	ACPI_DEBUG_PRINT ((ACPI_DB_INFO, "Max CPUs[%d], this CPU[%d].\n", NR_CPUS, smp_processor_id()));

	/* Only use C3 if we can control bus mastering. */
	if (acpi_fadt.V1_pm2_cnt_blk && acpi_fadt.pm2_cnt_len)
		bm_control = 1;

	/*
	 * Install idle handler.
	 *
	 * TBD: Linux-specific (need OSL function).
	 */
	pr_pm_idle_save = pm_idle;
	pm_idle = pr_power_idle;

	return_ACPI_STATUS(AE_OK);
}


/****************************************************************************
 *
 * FUNCTION:    pr_power_terminate
 *
 * PARAMETERS:  <none>
 *
 * RETURN:
 *
 * DESCRIPTION:
 *
 ****************************************************************************/

acpi_status
pr_power_terminate (void)
{
	FUNCTION_TRACE("pr_power_terminate");

	/*
	 * Remove idle handler.
	 *
	 * TBD: Linux-specific (need OSL function).
	 */
	pm_idle = pr_pm_idle_save;

	return_ACPI_STATUS(AE_OK);
}