diff options
Diffstat (limited to 'arch/arm/mach-vexpress/tc2_pm.c')
| -rw-r--r-- | arch/arm/mach-vexpress/tc2_pm.c | 352 |
1 files changed, 352 insertions, 0 deletions
diff --git a/arch/arm/mach-vexpress/tc2_pm.c b/arch/arm/mach-vexpress/tc2_pm.c new file mode 100644 index 000000000000..2b7c93a724ed --- /dev/null +++ b/arch/arm/mach-vexpress/tc2_pm.c @@ -0,0 +1,352 @@ +/* + * arch/arm/mach-vexpress/tc2_pm.c - TC2 power management support + * + * Created by: Nicolas Pitre, October 2012 + * Copyright: (C) 2012-2013 Linaro Limited + * + * Some portions of this file were originally written by Achin Gupta + * Copyright: (C) 2012 ARM Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/init.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/of_address.h> +#include <linux/spinlock.h> +#include <linux/errno.h> + +#include <asm/mcpm.h> +#include <asm/proc-fns.h> +#include <asm/cacheflush.h> +#include <asm/cputype.h> +#include <asm/cp15.h> + +#include <linux/arm-cci.h> + +#include "spc.h" + +/* SCC conf registers */ +#define A15_CONF 0x400 +#define A7_CONF 0x500 +#define SYS_INFO 0x700 +#define SPC_BASE 0xb00 + +/* + * We can't use regular spinlocks. In the switcher case, it is possible + * for an outbound CPU to call power_down() after its inbound counterpart + * is already live using the same logical CPU number which trips lockdep + * debugging. + */ +static arch_spinlock_t tc2_pm_lock = __ARCH_SPIN_LOCK_UNLOCKED; + +#define TC2_CLUSTERS 2 +#define TC2_MAX_CPUS_PER_CLUSTER 3 + +static unsigned int tc2_nr_cpus[TC2_CLUSTERS]; + +/* Keep per-cpu usage count to cope with unordered up/down requests */ +static int tc2_pm_use_count[TC2_MAX_CPUS_PER_CLUSTER][TC2_CLUSTERS]; + +#define tc2_cluster_unused(cluster) \ + (!tc2_pm_use_count[0][cluster] && \ + !tc2_pm_use_count[1][cluster] && \ + !tc2_pm_use_count[2][cluster]) + +static int tc2_pm_power_up(unsigned int cpu, unsigned int cluster) +{ + pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster); + if (cluster >= TC2_CLUSTERS || cpu >= tc2_nr_cpus[cluster]) + return -EINVAL; + + /* + * Since this is called with IRQs enabled, and no arch_spin_lock_irq + * variant exists, we need to disable IRQs manually here. + */ + local_irq_disable(); + arch_spin_lock(&tc2_pm_lock); + + if (tc2_cluster_unused(cluster)) + ve_spc_powerdown(cluster, false); + + tc2_pm_use_count[cpu][cluster]++; + if (tc2_pm_use_count[cpu][cluster] == 1) { + ve_spc_set_resume_addr(cluster, cpu, + virt_to_phys(mcpm_entry_point)); + ve_spc_cpu_wakeup_irq(cluster, cpu, true); + } else if (tc2_pm_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(); + } + + arch_spin_unlock(&tc2_pm_lock); + local_irq_enable(); + + return 0; +} + +static void tc2_pm_down(u64 residency) +{ + unsigned int mpidr, cpu, cluster; + bool last_man = false, skip_wfi = false; + + 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(cluster >= TC2_CLUSTERS || cpu >= TC2_MAX_CPUS_PER_CLUSTER); + + __mcpm_cpu_going_down(cpu, cluster); + + arch_spin_lock(&tc2_pm_lock); + BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP); + tc2_pm_use_count[cpu][cluster]--; + if (tc2_pm_use_count[cpu][cluster] == 0) { + ve_spc_cpu_wakeup_irq(cluster, cpu, true); + if (tc2_cluster_unused(cluster)) { + ve_spc_powerdown(cluster, true); + ve_spc_global_wakeup_irq(true); + last_man = true; + } + } else if (tc2_pm_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(); + + if (last_man && __mcpm_outbound_enter_critical(cpu, cluster)) { + arch_spin_unlock(&tc2_pm_lock); + + if (read_cpuid_part_number() == ARM_CPU_PART_CORTEX_A15) { + /* + * On the Cortex-A15 we need to disable + * L2 prefetching before flushing the cache. + */ + asm volatile( + "mcr p15, 1, %0, c15, c0, 3 \n\t" + "isb \n\t" + "dsb " + : : "r" (0x400) ); + } + + /* + * We need to disable and flush the whole (L1 and L2) cache. + * Let's do it in the safest possible way i.e. with + * no memory access within the following sequence + * including the stack. + * + * Note: fp is preserved to the stack explicitly prior doing + * this since adding it to the clobber list is incompatible + * with having CONFIG_FRAME_POINTER=y. + */ + asm volatile( + "str fp, [sp, #-4]! \n\t" + "mrc p15, 0, r0, c1, c0, 0 @ get CR \n\t" + "bic r0, r0, #"__stringify(CR_C)" \n\t" + "mcr p15, 0, r0, c1, c0, 0 @ set CR \n\t" + "isb \n\t" + "bl v7_flush_dcache_all \n\t" + "clrex \n\t" + "mrc p15, 0, r0, c1, c0, 1 @ get AUXCR \n\t" + "bic r0, r0, #(1 << 6) @ disable local coherency \n\t" + "mcr p15, 0, r0, c1, c0, 1 @ set AUXCR \n\t" + "isb \n\t" + "dsb \n\t" + "ldr fp, [sp], #4" + : : : "r0","r1","r2","r3","r4","r5","r6","r7", + "r9","r10","lr","memory"); + + cci_disable_port_by_cpu(mpidr); + + __mcpm_outbound_leave_critical(cluster, CLUSTER_DOWN); + } else { + /* + * If last man then undo any setup done previously. + */ + if (last_man) { + ve_spc_powerdown(cluster, false); + ve_spc_global_wakeup_irq(false); + } + + arch_spin_unlock(&tc2_pm_lock); + + /* + * We need to disable and flush only the L1 cache. + * Let's do it in the safest possible way as above. + */ + asm volatile( + "str fp, [sp, #-4]! \n\t" + "mrc p15, 0, r0, c1, c0, 0 @ get CR \n\t" + "bic r0, r0, #"__stringify(CR_C)" \n\t" + "mcr p15, 0, r0, c1, c0, 0 @ set CR \n\t" + "isb \n\t" + "bl v7_flush_dcache_louis \n\t" + "clrex \n\t" + "mrc p15, 0, r0, c1, c0, 1 @ get AUXCR \n\t" + "bic r0, r0, #(1 << 6) @ disable local coherency \n\t" + "mcr p15, 0, r0, c1, c0, 1 @ set AUXCR \n\t" + "isb \n\t" + "dsb \n\t" + "ldr fp, [sp], #4" + : : : "r0","r1","r2","r3","r4","r5","r6","r7", + "r9","r10","lr","memory"); + } + + __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 void tc2_pm_power_down(void) +{ + tc2_pm_down(0); +} + +static void tc2_pm_suspend(u64 residency) +{ + unsigned int mpidr, cpu, cluster; + + mpidr = read_cpuid_mpidr(); + cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); + cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); + ve_spc_set_resume_addr(cluster, cpu, virt_to_phys(mcpm_entry_point)); + tc2_pm_down(residency); +} + +static void tc2_pm_powered_up(void) +{ + unsigned int mpidr, cpu, cluster; + unsigned long flags; + + 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(cluster >= TC2_CLUSTERS || cpu >= TC2_MAX_CPUS_PER_CLUSTER); + + local_irq_save(flags); + arch_spin_lock(&tc2_pm_lock); + + if (tc2_cluster_unused(cluster)) { + ve_spc_powerdown(cluster, false); + ve_spc_global_wakeup_irq(false); + } + + if (!tc2_pm_use_count[cpu][cluster]) + tc2_pm_use_count[cpu][cluster] = 1; + + ve_spc_cpu_wakeup_irq(cluster, cpu, false); + ve_spc_set_resume_addr(cluster, cpu, 0); + + arch_spin_unlock(&tc2_pm_lock); + local_irq_restore(flags); +} + +static const struct mcpm_platform_ops tc2_pm_power_ops = { + .power_up = tc2_pm_power_up, + .power_down = tc2_pm_power_down, + .suspend = tc2_pm_suspend, + .powered_up = tc2_pm_powered_up, +}; + +static bool __init tc2_pm_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); + if (cluster >= TC2_CLUSTERS || cpu >= tc2_nr_cpus[cluster]) { + pr_err("%s: boot CPU is out of bound!\n", __func__); + return false; + } + tc2_pm_use_count[cpu][cluster] = 1; + return true; +} + +/* + * Enable cluster-level coherency, in preparation for turning on the MMU. + */ +static void __naked tc2_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 tc2_pm_init(void) +{ + int ret; + void __iomem *scc; + u32 a15_cluster_id, a7_cluster_id, sys_info; + struct device_node *np; + + /* + * The power management-related features are hidden behind + * SCC registers. We need to extract runtime information like + * cluster ids and number of CPUs really available in clusters. + */ + np = of_find_compatible_node(NULL, NULL, + "arm,vexpress-scc,v2p-ca15_a7"); + scc = of_iomap(np, 0); + if (!scc) + return -ENODEV; + + a15_cluster_id = readl_relaxed(scc + A15_CONF) & 0xf; + a7_cluster_id = readl_relaxed(scc + A7_CONF) & 0xf; + if (a15_cluster_id >= TC2_CLUSTERS || a7_cluster_id >= TC2_CLUSTERS) + return -EINVAL; + + sys_info = readl_relaxed(scc + SYS_INFO); + tc2_nr_cpus[a15_cluster_id] = (sys_info >> 16) & 0xf; + tc2_nr_cpus[a7_cluster_id] = (sys_info >> 20) & 0xf; + + /* + * A subset of the SCC registers is also used to communicate + * with the SPC (power controller). We need to be able to + * drive it very early in the boot process to power up + * processors, so we initialize the SPC driver here. + */ + ret = ve_spc_init(scc + SPC_BASE, a15_cluster_id); + if (ret) + return ret; + + if (!cci_probed()) + return -ENODEV; + + if (!tc2_pm_usage_count_init()) + return -EINVAL; + + ret = mcpm_platform_register(&tc2_pm_power_ops); + if (!ret) { + mcpm_sync_init(tc2_pm_power_up_setup); + pr_info("TC2 power management initialized\n"); + } + return ret; +} + +early_initcall(tc2_pm_init); |