ARM: sun6i: Add SMP support for the Allwinner A31

The A31 is a quad Cortex-A7. Add the logic to use the IPs used to
control the CPU configuration and the CPU power so that we can bring up
secondary CPUs at boot.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

1 files changed, 124 insertions, 0 deletions

diff --git a/arch/arm/mach-sunxi/platsmp.c b/arch/arm/mach-sunxi/platsmp.c
new file mode 100644
index 000000000000..7b141d8342a1
--- /dev/null
+++ b/arch/arm/mach-sunxi/platsmp.c
@@ -0,0 +1,124 @@
+/*
+ * SMP support for Allwinner SoCs
+ *
+ * Copyright (C) 2013 Maxime Ripard
+ *
+ * Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * Based on code
+ *  Copyright (C) 2012-2013 Allwinner Ltd.
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/memory.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/smp.h>
+
+#include "common.h"
+
+#define CPUCFG_CPU_PWR_CLAMP_STATUS_REG(cpu)    ((cpu) * 0x40 + 0x64)
+#define CPUCFG_CPU_RST_CTRL_REG(cpu)            (((cpu) + 1) * 0x40)
+#define CPUCFG_CPU_CTRL_REG(cpu)                (((cpu) + 1) * 0x40 + 0x04)
+#define CPUCFG_CPU_STATUS_REG(cpu)              (((cpu) + 1) * 0x40 + 0x08)
+#define CPUCFG_GEN_CTRL_REG                     0x184
+#define CPUCFG_PRIVATE0_REG                     0x1a4
+#define CPUCFG_PRIVATE1_REG                     0x1a8
+#define CPUCFG_DBG_CTL0_REG                     0x1e0
+#define CPUCFG_DBG_CTL1_REG                     0x1e4
+
+#define PRCM_CPU_PWROFF_REG                     0x100
+#define PRCM_CPU_PWR_CLAMP_REG(cpu)             (((cpu) * 4) + 0x140)
+
+static void __iomem *cpucfg_membase;
+static void __iomem *prcm_membase;
+
+static DEFINE_SPINLOCK(cpu_lock);
+
+static void __init sun6i_smp_prepare_cpus(unsigned int max_cpus)
+{
+        struct device_node *node;
+
+        node = of_find_compatible_node(NULL, NULL, "allwinner,sun6i-a31-prcm");
+        if (!node) {
+                pr_err("Missing A31 PRCM node in the device tree\n");
+                return;
+        }
+
+        prcm_membase = of_iomap(node, 0);
+        if (!prcm_membase) {
+                pr_err("Couldn't map A31 PRCM registers\n");
+                return;
+        }
+
+        node = of_find_compatible_node(NULL, NULL,
+                                       "allwinner,sun6i-a31-cpuconfig");
+        if (!node) {
+                pr_err("Missing A31 CPU config node in the device tree\n");
+                return;
+        }
+
+        cpucfg_membase = of_iomap(node, 0);
+        if (!cpucfg_membase)
+                pr_err("Couldn't map A31 CPU config registers\n");
+
+}
+
+static int sun6i_smp_boot_secondary(unsigned int cpu,
+                                    struct task_struct *idle)
+{
+        u32 reg;
+        int i;
+
+        if (!(prcm_membase && cpucfg_membase))
+                return -EFAULT;
+
+        spin_lock(&cpu_lock);
+
+        /* Set CPU boot address */
+        writel(virt_to_phys(sun6i_secondary_startup),
+               cpucfg_membase + CPUCFG_PRIVATE0_REG);
+
+        /* Assert the CPU core in reset */
+        writel(0, cpucfg_membase + CPUCFG_CPU_RST_CTRL_REG(cpu));
+
+        /* Assert the L1 cache in reset */
+        reg = readl(cpucfg_membase + CPUCFG_GEN_CTRL_REG);
+        writel(reg & ~BIT(cpu), cpucfg_membase + CPUCFG_GEN_CTRL_REG);
+
+        /* Disable external debug access */
+        reg = readl(cpucfg_membase + CPUCFG_DBG_CTL1_REG);
+        writel(reg & ~BIT(cpu), cpucfg_membase + CPUCFG_DBG_CTL1_REG);
+
+        /* Power up the CPU */
+        for (i = 0; i <= 8; i++)
+                writel(0xff >> i, prcm_membase + PRCM_CPU_PWR_CLAMP_REG(cpu));
+        mdelay(10);
+
+        /* Clear CPU power-off gating */
+        reg = readl(prcm_membase + PRCM_CPU_PWROFF_REG);
+        writel(reg & ~BIT(cpu), prcm_membase + PRCM_CPU_PWROFF_REG);
+        mdelay(1);
+
+        /* Deassert the CPU core reset */
+        writel(3, cpucfg_membase + CPUCFG_CPU_RST_CTRL_REG(cpu));
+
+        /* Enable back the external debug accesses */
+        reg = readl(cpucfg_membase + CPUCFG_DBG_CTL1_REG);
+        writel(reg | BIT(cpu), cpucfg_membase + CPUCFG_DBG_CTL1_REG);
+
+        spin_unlock(&cpu_lock);
+
+        return 0;
+}
+
+struct smp_operations sun6i_smp_ops __initdata = {
+        .smp_prepare_cpus       = sun6i_smp_prepare_cpus,
+        .smp_boot_secondary     = sun6i_smp_boot_secondary,
+};