ARM: vexpress: introduce DCSCB support
This adds basic CPU and cluster reset controls on RTSM for the
A15x4-A7x4 model configuration using the Dual Cluster System
Configuration Block (DCSCB).
The cache coherency interconnect (CCI) is not handled yet.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Pawel Moll <pawel.moll@arm.com>
diff --git a/arch/arm/mach-vexpress/dcscb.c b/arch/arm/mach-vexpress/dcscb.c
new file mode 100644
index 0000000..2ca4bbc
--- /dev/null
+++ b/arch/arm/mach-vexpress/dcscb.c
@@ -0,0 +1,164 @@
+/*
+ * 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 <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/spinlock.h>
+#include <linux/errno.h>
+#include <linux/of_address.h>
+#include <linux/vexpress.h>
+
+#include <asm/mcpm.h>
+#include <asm/proc-fns.h>
+#include <asm/cacheflush.h>
+#include <asm/cputype.h>
+#include <asm/cp15.h>
+
+
+#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_power_up(unsigned int cpu, unsigned int cluster)
+{
+ unsigned int rst_hold, cpumask = (1 << cpu);
+
+ pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
+ if (cpu >= 4 || cluster >= 2)
+ 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(&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;
+ }
+ rst_hold &= ~(cpumask | (cpumask << 4));
+ writel_relaxed(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4);
+
+ arch_spin_unlock(&dcscb_lock);
+ local_irq_enable();
+
+ return 0;
+}
+
+static void dcscb_power_down(void)
+{
+ unsigned int mpidr, cpu, cluster, rst_hold, cpumask, last_man;
+
+ 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);
+
+ 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);
+ arch_spin_unlock(&dcscb_lock);
+ last_man = (rst_hold & (1 << 8));
+
+ /*
+ * Now let's clean our L1 cache and shut ourself down.
+ * If we're the last CPU in this cluster then clean L2 too.
+ */
+
+ /*
+ * A15/A7 can hit in the cache with SCTLR.C=0, so we don't need
+ * a preliminary flush here for those CPUs. At least, that's
+ * the theory -- without the extra flush, Linux explodes on
+ * RTSM (to be investigated)..
+ */
+ flush_cache_louis();
+ set_cr(get_cr() & ~CR_C);
+
+ if (!last_man) {
+ flush_cache_louis();
+ } else {
+ flush_cache_all();
+ outer_flush_all();
+ }
+
+ /* Disable local coherency by clearing the ACTLR "SMP" bit: */
+ set_auxcr(get_auxcr() & ~(1 << 6));
+
+ /* Now we are prepared for power-down, do it: */
+ dsb();
+ 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 int __init dcscb_init(void)
+{
+ struct device_node *node;
+ int ret;
+
+ 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;
+
+ ret = mcpm_platform_register(&dcscb_power_ops);
+ 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);