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

[Lorenzo Pieralisi <lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org>]

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

[...]

> +       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.

Thanks,
Lorenzo

> +               /* 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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