[CPUFREQ] ARM Exynos4210 PM/Suspend compatibility with different bootloaders
We have various bootloaders for Exynos4210 machines. Some of they set the ARM core frequency at boot time even when the boot is a resume from suspend-to-RAM. Such changes may create inconsistency in the data of CPUFREQ driver and have incurred hang issues with suspend-to-RAM. This patch enables to save and restore CPU frequencies with pm-notifier and sets the frequency at the initial (boot-time) value so that there wouldn't be any inconsistency between bootloader and kernel. This patch does not use CPUFREQ's suspend/resume callbacks because they are syscore-ops, which do not allow to use mutex that is being used by regulators that are used by the target function. This also prevents any CPUFREQ transitions during suspend-resume context, which could be dangerous at noirq-context along with regulator framework. Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Dave Jones <davej@redhat.com>
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8efd072b32
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@ -17,6 +17,8 @@
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#include <linux/slab.h>
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#include <linux/regulator/consumer.h>
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#include <linux/cpufreq.h>
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#include <linux/notifier.h>
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#include <linux/suspend.h>
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#include <mach/map.h>
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#include <mach/regs-clock.h>
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@ -36,6 +38,10 @@ static struct regulator *int_regulator;
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static struct cpufreq_freqs freqs;
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static unsigned int memtype;
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static unsigned int locking_frequency;
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static bool frequency_locked;
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static DEFINE_MUTEX(cpufreq_lock);
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enum exynos4_memory_type {
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DDR2 = 4,
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LPDDR2,
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@ -405,22 +411,32 @@ static int exynos4_target(struct cpufreq_policy *policy,
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{
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unsigned int index, old_index;
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unsigned int arm_volt, int_volt;
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int err = -EINVAL;
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freqs.old = exynos4_getspeed(policy->cpu);
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mutex_lock(&cpufreq_lock);
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if (frequency_locked && target_freq != locking_frequency) {
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err = -EAGAIN;
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goto out;
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}
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if (cpufreq_frequency_table_target(policy, exynos4_freq_table,
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freqs.old, relation, &old_index))
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return -EINVAL;
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goto out;
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if (cpufreq_frequency_table_target(policy, exynos4_freq_table,
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target_freq, relation, &index))
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return -EINVAL;
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goto out;
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err = 0;
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freqs.new = exynos4_freq_table[index].frequency;
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freqs.cpu = policy->cpu;
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if (freqs.new == freqs.old)
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return 0;
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goto out;
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/* get the voltage value */
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arm_volt = exynos4_volt_table[index].arm_volt;
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@ -447,10 +463,16 @@ static int exynos4_target(struct cpufreq_policy *policy,
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cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
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return 0;
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out:
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mutex_unlock(&cpufreq_lock);
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return err;
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}
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#ifdef CONFIG_PM
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/*
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* These suspend/resume are used as syscore_ops, it is already too
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* late to set regulator voltages at this stage.
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*/
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static int exynos4_cpufreq_suspend(struct cpufreq_policy *policy)
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{
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return 0;
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@ -462,6 +484,78 @@ static int exynos4_cpufreq_resume(struct cpufreq_policy *policy)
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}
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#endif
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/**
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* exynos4_cpufreq_pm_notifier - block CPUFREQ's activities in suspend-resume
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* context
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* @notifier
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* @pm_event
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* @v
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*
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* While frequency_locked == true, target() ignores every frequency but
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* locking_frequency. The locking_frequency value is the initial frequency,
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* which is set by the bootloader. In order to eliminate possible
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* inconsistency in clock values, we save and restore frequencies during
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* suspend and resume and block CPUFREQ activities. Note that the standard
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* suspend/resume cannot be used as they are too deep (syscore_ops) for
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* regulator actions.
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*/
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static int exynos4_cpufreq_pm_notifier(struct notifier_block *notifier,
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unsigned long pm_event, void *v)
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{
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struct cpufreq_policy *policy = cpufreq_cpu_get(0); /* boot CPU */
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static unsigned int saved_frequency;
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unsigned int temp;
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mutex_lock(&cpufreq_lock);
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switch (pm_event) {
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case PM_SUSPEND_PREPARE:
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if (frequency_locked)
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goto out;
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frequency_locked = true;
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if (locking_frequency) {
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saved_frequency = exynos4_getspeed(0);
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mutex_unlock(&cpufreq_lock);
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exynos4_target(policy, locking_frequency,
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CPUFREQ_RELATION_H);
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mutex_lock(&cpufreq_lock);
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}
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break;
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case PM_POST_SUSPEND:
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if (saved_frequency) {
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/*
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* While frequency_locked, only locking_frequency
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* is valid for target(). In order to use
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* saved_frequency while keeping frequency_locked,
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* we temporarly overwrite locking_frequency.
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*/
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temp = locking_frequency;
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locking_frequency = saved_frequency;
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mutex_unlock(&cpufreq_lock);
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exynos4_target(policy, locking_frequency,
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CPUFREQ_RELATION_H);
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mutex_lock(&cpufreq_lock);
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locking_frequency = temp;
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}
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frequency_locked = false;
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break;
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}
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out:
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mutex_unlock(&cpufreq_lock);
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return NOTIFY_OK;
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}
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static struct notifier_block exynos4_cpufreq_nb = {
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.notifier_call = exynos4_cpufreq_pm_notifier,
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};
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static int exynos4_cpufreq_cpu_init(struct cpufreq_policy *policy)
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{
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int ret;
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@ -522,6 +616,8 @@ static int __init exynos4_cpufreq_init(void)
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if (IS_ERR(cpu_clk))
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return PTR_ERR(cpu_clk);
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locking_frequency = exynos4_getspeed(0);
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moutcore = clk_get(NULL, "moutcore");
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if (IS_ERR(moutcore))
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goto out;
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@ -561,6 +657,8 @@ static int __init exynos4_cpufreq_init(void)
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printk(KERN_DEBUG "%s: memtype= 0x%x\n", __func__, memtype);
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}
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register_pm_notifier(&exynos4_cpufreq_nb);
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return cpufreq_register_driver(&exynos4_driver);
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out:
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