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author | Nicolas Pitre <nicolas.pitre@linaro.org> | 2012-07-16 22:07:10 -0400 |
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committer | Nicolas Pitre <nicolas.pitre@linaro.org> | 2013-05-29 15:50:35 -0400 |
commit | 13eae144ec754ab64521891d2cffc3156f6f083f (patch) | |
tree | 384c5edf609e0ffb3ebf0cbadf2ec19d1007b037 /arch | |
parent | 1e904e1bf6f1285cc2dd5696c44b7cf78cda643f (diff) | |
download | op-kernel-dev-13eae144ec754ab64521891d2cffc3156f6f083f.zip op-kernel-dev-13eae144ec754ab64521891d2cffc3156f6f083f.tar.gz |
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>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/arm/mach-vexpress/dcscb.c | 74 |
1 files changed, 59 insertions, 15 deletions
diff --git a/arch/arm/mach-vexpress/dcscb.c b/arch/arm/mach-vexpress/dcscb.c index 2ca4bbc..65dee78 100644 --- a/arch/arm/mach-vexpress/dcscb.c +++ b/arch/arm/mach-vexpress/dcscb.c @@ -44,6 +44,7 @@ static arch_spinlock_t dcscb_lock = __ARCH_SPIN_LOCK_UNLOCKED; static void __iomem *dcscb_base; +static int dcscb_use_count[4][2]; static int dcscb_power_up(unsigned int cpu, unsigned int cluster) { @@ -60,14 +61,27 @@ static int dcscb_power_up(unsigned int cpu, unsigned int cluster) local_irq_disable(); arch_spin_lock(&dcscb_lock); - rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4); - if (rst_hold & (1 << 8)) { - /* remove cluster reset and add individual CPU's reset */ - rst_hold &= ~(1 << 8); - rst_hold |= 0xf; + dcscb_use_count[cpu][cluster]++; + if (dcscb_use_count[cpu][cluster] == 1) { + rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4); + if (rst_hold & (1 << 8)) { + /* remove cluster reset and add individual CPU's reset */ + rst_hold &= ~(1 << 8); + rst_hold |= 0xf; + } + rst_hold &= ~(cpumask | (cpumask << 4)); + writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4); + } else if (dcscb_use_count[cpu][cluster] != 2) { + /* + * The only possible values are: + * 0 = CPU down + * 1 = CPU (still) up + * 2 = CPU requested to be up before it had a chance + * to actually make itself down. + * Any other value is a bug. + */ + BUG(); } - rst_hold &= ~(cpumask | (cpumask << 4)); - writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4); arch_spin_unlock(&dcscb_lock); local_irq_enable(); @@ -77,7 +91,8 @@ static int dcscb_power_up(unsigned int cpu, unsigned int cluster) static void dcscb_power_down(void) { - unsigned int mpidr, cpu, cluster, rst_hold, cpumask, last_man; + unsigned int mpidr, cpu, cluster, rst_hold, cpumask; + bool last_man = false, skip_wfi = false; mpidr = read_cpuid_mpidr(); cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); @@ -88,13 +103,26 @@ static void dcscb_power_down(void) BUG_ON(cpu >= 4 || cluster >= 2); arch_spin_lock(&dcscb_lock); - rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4); - rst_hold |= cpumask; - if (((rst_hold | (rst_hold >> 4)) & 0xf) == 0xf) - rst_hold |= (1 << 8); - writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4); + dcscb_use_count[cpu][cluster]--; + if (dcscb_use_count[cpu][cluster] == 0) { + rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4); + rst_hold |= cpumask; + if (((rst_hold | (rst_hold >> 4)) & 0xf) == 0xf) { + rst_hold |= (1 << 8); + last_man = true; + } + writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4); + } else if (dcscb_use_count[cpu][cluster] == 1) { + /* + * A power_up request went ahead of us. + * Even if we do not want to shut this CPU down, + * the caller expects a certain state as if the WFI + * was aborted. So let's continue with cache cleaning. + */ + skip_wfi = true; + } else + BUG(); arch_spin_unlock(&dcscb_lock); - last_man = (rst_hold & (1 << 8)); /* * Now let's clean our L1 cache and shut ourself down. @@ -122,7 +150,8 @@ static void dcscb_power_down(void) /* Now we are prepared for power-down, do it: */ dsb(); - wfi(); + if (!skip_wfi) + wfi(); /* Not dead at this point? Let our caller cope. */ } @@ -132,6 +161,19 @@ static const struct mcpm_platform_ops dcscb_power_ops = { .power_down = dcscb_power_down, }; +static void __init dcscb_usage_count_init(void) +{ + unsigned int mpidr, cpu, cluster; + + mpidr = read_cpuid_mpidr(); + cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); + cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); + + pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster); + BUG_ON(cpu >= 4 || cluster >= 2); + dcscb_use_count[cpu][cluster] = 1; +} + static int __init dcscb_init(void) { struct device_node *node; @@ -144,6 +186,8 @@ static int __init dcscb_init(void) if (!dcscb_base) return -EADDRNOTAVAIL; + dcscb_usage_count_init(); + ret = mcpm_platform_register(&dcscb_power_ops); if (ret) { iounmap(dcscb_base); |