Re: [PATCH v3 5/6] arm: exynos: Add MCPM call-back functions

Hi Lorenzo,

On Wed, Apr 30, 2014 at 8:29 PM, Lorenzo Pieralisi
[off-list ref] wrote:

On Sat, Apr 26, 2014 at 05:05:47PM +0100, Abhilash Kesavan wrote:

[...]

quoted

+       if (last_man && __mcpm_outbound_enter_critical(cpu, cluster)) {
+               arch_spin_unlock(&exynos_mcpm_lock);
+

I missed it on first review, but you do need to disable L2 prefetching
on A15 here as we do in TC2 (tc2_pm.c), this power down procedure is not
compliant otherwise.

OK, I see this as being part of the power down sequence described in
A15 TRM, will add.

Regards,
Abhilash

Thanks,
Lorenzo

quoted

+               /* Flush all cache levels for this cluster. */
+               exynos_v7_exit_coherency_flush(all);
+
+               /*
+                * Disable cluster-level coherency by masking
+                * incoming snoops and DVM messages:
+                */
+               cci_disable_port_by_cpu(mpidr);
+
+               __mcpm_outbound_leave_critical(cluster, CLUSTER_DOWN);
+       } else {
+               arch_spin_unlock(&exynos_mcpm_lock);
+
+               /* Disable and flush the local CPU cache. */
+               exynos_v7_exit_coherency_flush(louis);
+       }
+
+       __mcpm_cpu_down(cpu, cluster);
+
+       /* Now we are prepared for power-down, do it: */
+       if (!skip_wfi)
+               wfi();
+
+       /* Not dead at this point?  Let our caller cope. */
+}
+
+static int exynos_power_down_finish(unsigned int cpu, unsigned int cluster)
+{
+       unsigned int tries = 100;
+       unsigned int cpunr = cpu + (cluster * EXYNOS5420_CPUS_PER_CLUSTER);
+
+       pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
+       BUG_ON(cpu >= EXYNOS5420_CPUS_PER_CLUSTER ||
+                       cluster >= EXYNOS5420_NR_CLUSTERS);
+
+       /* Wait for the core state to be OFF */
+       while (tries--) {
+               if (ACCESS_ONCE(cpu_use_count[cpu][cluster]) == 0) {
+                       if ((exynos_cpu_power_state(cpunr) == 0))
+                               return 0; /* success: the CPU is halted */
+               }
+
+               /* Otherwise, wait and retry: */
+               msleep(1);
+       }
+
+       return -ETIMEDOUT; /* timeout */
+}
+
+static const struct mcpm_platform_ops exynos_power_ops = {
+       .power_up               = exynos_power_up,
+       .power_down             = exynos_power_down,
+       .power_down_finish      = exynos_power_down_finish,
+};
+
+static void __init exynos_mcpm_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 >= EXYNOS5420_CPUS_PER_CLUSTER  ||
+                       cluster >= EXYNOS5420_NR_CLUSTERS);
+
+       cpu_use_count[cpu][cluster] = 1;
+}
+
+/*
+ * Enable cluster-level coherency, in preparation for turning on the MMU.
+ */
+static void __naked exynos_pm_power_up_setup(unsigned int affinity_level)
+{
+       asm volatile ("\n"
+       "cmp    r0, #1\n"
+       "bxne   lr\n"
+       "b      cci_enable_port_for_self");
+}
+
+static int __init exynos_mcpm_init(void)
+{
+       int ret = 0;
+
+       if (!soc_is_exynos5420())
+               return -ENODEV;
+
+       if (!cci_probed())
+               return -ENODEV;
+
+       /*
+        * To increase the stability of KFC reset we need to program
+        * the PMU SPARE3 register
+        */
+       __raw_writel(EXYNOS5420_SWRESET_KFC_SEL, S5P_PMU_SPARE3);
+
+       exynos_mcpm_usage_count_init();
+
+       ret = mcpm_platform_register(&exynos_power_ops);
+       if (!ret)
+               ret = mcpm_sync_init(exynos_pm_power_up_setup);
+       if (ret)
+               return ret;
+
+       mcpm_smp_set_ops();
+
+       pr_info("Exynos MCPM support installed\n");
+
+       /*
+        * Future entries into the kernel can now go
+        * through the cluster entry vectors.
+        */
+       __raw_writel(virt_to_phys(mcpm_entry_point),
+               REG_ENTRY_ADDR);
+
+       return ret;
+}
+
+early_initcall(exynos_mcpm_init);

diff --git a/arch/arm/mach-exynos/regs-pmu.h b/arch/arm/mach-exynos/regs-pmu.h
index 6685ebf..f44d318 100644
--- a/arch/arm/mach-exynos/regs-pmu.h
+++ b/arch/arm/mach-exynos/regs-pmu.h

@@ -38,6 +38,7 @@
 #define S5P_INFORM5                            S5P_PMUREG(0x0814)
 #define S5P_INFORM6                            S5P_PMUREG(0x0818)
 #define S5P_INFORM7                            S5P_PMUREG(0x081C)
+#define S5P_PMU_SPARE3                         S5P_PMUREG(0x090C)

 #define S5P_ARM_CORE0_LOWPWR                   S5P_PMUREG(0x1000)
 #define S5P_DIS_IRQ_CORE0                      S5P_PMUREG(0x1004)

@@ -325,4 +326,6 @@

 #define EXYNOS5_OPTION_USE_RETENTION                           (1 << 4)

+#define EXYNOS5420_SWRESET_KFC_SEL                             0x3
+
 #endif /* __ASM_ARCH_REGS_PMU_H */
--

1.8.3.2

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