/* * arch/arm/mach-vexpress/dcscb.c - Dual Cluster System Configuration Block * * Created by: Nicolas Pitre, May 2012 * Copyright: (C) 2012-2013 Linaro 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 #include #include #include #include #include #include #include #include #include #include #include #include #define RST_HOLD0 0x0 #define RST_HOLD1 0x4 #define SYS_SWRESET 0x8 #define RST_STAT0 0xc #define RST_STAT1 0x10 #define EAG_CFG_R 0x20 #define EAG_CFG_W 0x24 #define KFC_CFG_R 0x28 #define KFC_CFG_W 0x2c #define DCS_CFG_R 0x30 /* * We can't use regular spinlocks. In the switcher case, it is possible * for an outbound CPU to call power_down() while its inbound counterpart * is already live using the same logical CPU number which trips lockdep * debugging. */ 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_allcpus_mask[2]; static int dcscb_power_up(unsigned int cpu, unsigned int cluster) { unsigned int rst_hold, cpumask = (1 << cpu); unsigned int all_mask; pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster); if (cpu >= 4 || cluster >= 2) return -EINVAL; all_mask = dcscb_allcpus_mask[cluster]; /* * 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(&dcscb_lock); 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 |= all_mask; } 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(); } arch_spin_unlock(&dcscb_lock); local_irq_enable(); return 0; } static void dcscb_power_down(void) { unsigned int mpidr, cpu, cluster, rst_hold, cpumask, all_mask; bool last_man = false, skip_wfi = false; mpidr = read_cpuid_mpidr(); cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); cpumask = (1 << cpu); pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster); BUG_ON(cpu >= 4 || cluster >= 2); all_mask = dcscb_allcpus_mask[cluster]; __mcpm_cpu_going_down(cpu, cluster); arch_spin_lock(&dcscb_lock); BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP); 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)) & all_mask) == all_mask) { 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(); if (last_man && __mcpm_outbound_enter_critical(cpu, cluster)) { arch_spin_unlock(&dcscb_lock); /* Flush all cache levels for this cluster. */ v7_exit_coherency_flush(all); /* * A full outer cache flush could be needed at this point * on platforms with such a cache, depending on where the * outer cache sits. In some cases the notion of a "last * cluster standing" would need to be implemented if the * outer cache is shared across clusters. In any case, when * the outer cache needs flushing, there is no concurrent * access to the cache controller to worry about and no * special locking besides what is already provided by the * MCPM state machinery is needed. */ /* * 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(&dcscb_lock); /* Disable and flush the local CPU cache. */ v7_exit_coherency_flush(louis); } __mcpm_cpu_down(cpu, cluster); /* Now we are prepared for power-down, do it: */ dsb(); if (!skip_wfi) wfi(); /* Not dead at this point? Let our caller cope. */ } static const struct mcpm_platform_ops dcscb_power_ops = { .power_up = dcscb_power_up, .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; } extern void dcscb_power_up_setup(unsigned int affinity_level); static int __init dcscb_init(void) { struct device_node *node; unsigned int cfg; int ret; if (!cci_probed()) return -ENODEV; node = of_find_compatible_node(NULL, NULL, "arm,rtsm,dcscb"); if (!node) return -ENODEV; dcscb_base = of_iomap(node, 0); if (!dcscb_base) return -EADDRNOTAVAIL; cfg = readl_relaxed(dcscb_base + DCS_CFG_R); dcscb_allcpus_mask[0] = (1 << (((cfg >> 16) >> (0 << 2)) & 0xf)) - 1; dcscb_allcpus_mask[1] = (1 << (((cfg >> 16) >> (1 << 2)) & 0xf)) - 1; dcscb_usage_count_init(); ret = mcpm_platform_register(&dcscb_power_ops); if (!ret) ret = mcpm_sync_init(dcscb_power_up_setup); if (ret) { iounmap(dcscb_base); return ret; } pr_info("VExpress DCSCB support installed\n"); /* * Future entries into the kernel can now go * through the cluster entry vectors. */ vexpress_flags_set(virt_to_phys(mcpm_entry_point)); return 0; } early_initcall(dcscb_init);