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ARM: vexpress/dcscb: add CPU use counts to the power up/down API implementation
It is possible for a CPU to be told to power up before it managed to power itself down. Solve this race with a usage count to deal with this possibility as mandated by the MCPM API definition. Signed-off-by: nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Pawel Moll <pawel.moll@arm.com>
This commit is contained in:
parent
1e904e1bf6
commit
13eae144ec
1 changed files with 59 additions and 15 deletions
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@ -44,6 +44,7 @@
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static arch_spinlock_t dcscb_lock = __ARCH_SPIN_LOCK_UNLOCKED;
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static arch_spinlock_t dcscb_lock = __ARCH_SPIN_LOCK_UNLOCKED;
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static void __iomem *dcscb_base;
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static void __iomem *dcscb_base;
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static int dcscb_use_count[4][2];
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static int dcscb_power_up(unsigned int cpu, unsigned int cluster)
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static int dcscb_power_up(unsigned int cpu, unsigned int cluster)
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{
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{
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@ -60,14 +61,27 @@ static int dcscb_power_up(unsigned int cpu, unsigned int cluster)
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local_irq_disable();
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local_irq_disable();
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arch_spin_lock(&dcscb_lock);
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arch_spin_lock(&dcscb_lock);
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rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4);
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dcscb_use_count[cpu][cluster]++;
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if (rst_hold & (1 << 8)) {
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if (dcscb_use_count[cpu][cluster] == 1) {
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/* remove cluster reset and add individual CPU's reset */
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rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4);
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rst_hold &= ~(1 << 8);
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if (rst_hold & (1 << 8)) {
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rst_hold |= 0xf;
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/* remove cluster reset and add individual CPU's reset */
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rst_hold &= ~(1 << 8);
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rst_hold |= 0xf;
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}
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rst_hold &= ~(cpumask | (cpumask << 4));
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writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4);
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} else if (dcscb_use_count[cpu][cluster] != 2) {
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/*
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* The only possible values are:
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* 0 = CPU down
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* 1 = CPU (still) up
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* 2 = CPU requested to be up before it had a chance
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* to actually make itself down.
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* Any other value is a bug.
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*/
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BUG();
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}
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}
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rst_hold &= ~(cpumask | (cpumask << 4));
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writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4);
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arch_spin_unlock(&dcscb_lock);
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arch_spin_unlock(&dcscb_lock);
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local_irq_enable();
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local_irq_enable();
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@ -77,7 +91,8 @@ static int dcscb_power_up(unsigned int cpu, unsigned int cluster)
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static void dcscb_power_down(void)
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static void dcscb_power_down(void)
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{
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{
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unsigned int mpidr, cpu, cluster, rst_hold, cpumask, last_man;
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unsigned int mpidr, cpu, cluster, rst_hold, cpumask;
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bool last_man = false, skip_wfi = false;
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mpidr = read_cpuid_mpidr();
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mpidr = read_cpuid_mpidr();
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cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
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cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
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@ -88,13 +103,26 @@ static void dcscb_power_down(void)
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BUG_ON(cpu >= 4 || cluster >= 2);
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BUG_ON(cpu >= 4 || cluster >= 2);
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arch_spin_lock(&dcscb_lock);
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arch_spin_lock(&dcscb_lock);
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rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4);
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dcscb_use_count[cpu][cluster]--;
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rst_hold |= cpumask;
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if (dcscb_use_count[cpu][cluster] == 0) {
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if (((rst_hold | (rst_hold >> 4)) & 0xf) == 0xf)
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rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4);
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rst_hold |= (1 << 8);
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rst_hold |= cpumask;
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writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4);
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if (((rst_hold | (rst_hold >> 4)) & 0xf) == 0xf) {
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rst_hold |= (1 << 8);
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last_man = true;
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}
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writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4);
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} else if (dcscb_use_count[cpu][cluster] == 1) {
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/*
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* A power_up request went ahead of us.
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* Even if we do not want to shut this CPU down,
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* the caller expects a certain state as if the WFI
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* was aborted. So let's continue with cache cleaning.
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*/
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skip_wfi = true;
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} else
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BUG();
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arch_spin_unlock(&dcscb_lock);
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arch_spin_unlock(&dcscb_lock);
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last_man = (rst_hold & (1 << 8));
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/*
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/*
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* Now let's clean our L1 cache and shut ourself down.
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* Now let's clean our L1 cache and shut ourself down.
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@ -122,7 +150,8 @@ static void dcscb_power_down(void)
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/* Now we are prepared for power-down, do it: */
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/* Now we are prepared for power-down, do it: */
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dsb();
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dsb();
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wfi();
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if (!skip_wfi)
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wfi();
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/* Not dead at this point? Let our caller cope. */
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/* Not dead at this point? Let our caller cope. */
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}
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}
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@ -132,6 +161,19 @@ static const struct mcpm_platform_ops dcscb_power_ops = {
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.power_down = dcscb_power_down,
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.power_down = dcscb_power_down,
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};
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};
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static void __init dcscb_usage_count_init(void)
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{
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unsigned int mpidr, cpu, cluster;
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mpidr = read_cpuid_mpidr();
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cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
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cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
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pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
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BUG_ON(cpu >= 4 || cluster >= 2);
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dcscb_use_count[cpu][cluster] = 1;
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}
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static int __init dcscb_init(void)
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static int __init dcscb_init(void)
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{
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{
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struct device_node *node;
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struct device_node *node;
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@ -144,6 +186,8 @@ static int __init dcscb_init(void)
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if (!dcscb_base)
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if (!dcscb_base)
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return -EADDRNOTAVAIL;
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return -EADDRNOTAVAIL;
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dcscb_usage_count_init();
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ret = mcpm_platform_register(&dcscb_power_ops);
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ret = mcpm_platform_register(&dcscb_power_ops);
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if (ret) {
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if (ret) {
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iounmap(dcscb_base);
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iounmap(dcscb_base);
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