[PATCH 1/2] ARM: oxnas: Add OX820 SMP support
Neil Armstrong
narmstrong at baylibre.com
Mon Oct 17 01:43:02 PDT 2016
The Oxford Semiconductor OX820 is a ARM11MPcore based SoC sharing some
features with the OX810 earlier SoC.
This patch adds the core to wake up the second core.
Signed-off-by: Neil Armstrong <narmstrong at baylibre.com>
---
arch/arm/mach-oxnas/Makefile | 2 +
arch/arm/mach-oxnas/headsmp.S | 28 ++++++++
arch/arm/mach-oxnas/hotplug.c | 111 +++++++++++++++++++++++++++++
arch/arm/mach-oxnas/platsmp.c | 161 ++++++++++++++++++++++++++++++++++++++++++
4 files changed, 302 insertions(+)
create mode 100644 arch/arm/mach-oxnas/Makefile
create mode 100644 arch/arm/mach-oxnas/headsmp.S
create mode 100644 arch/arm/mach-oxnas/hotplug.c
create mode 100644 arch/arm/mach-oxnas/platsmp.c
diff --git a/arch/arm/mach-oxnas/Makefile b/arch/arm/mach-oxnas/Makefile
new file mode 100644
index 0000000..b625906
--- /dev/null
+++ b/arch/arm/mach-oxnas/Makefile
@@ -0,0 +1,2 @@
+obj-$(CONFIG_SMP) += platsmp.o headsmp.o
+obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
diff --git a/arch/arm/mach-oxnas/headsmp.S b/arch/arm/mach-oxnas/headsmp.S
new file mode 100644
index 0000000..2a94dcb
--- /dev/null
+++ b/arch/arm/mach-oxnas/headsmp.S
@@ -0,0 +1,28 @@
+/*
+ * linux/arch/arm/mach-oxnas/headsmp.S
+ *
+ * Copyright (C) 2013 Ma Haijun <mahaijuns at gmail.com>
+ * Copyright (c) 2003 ARM Limited
+ * All Rights Reserved
+ *
+ * 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/linkage.h>
+#include <linux/init.h>
+
+ __INIT
+
+/*
+ * OX820 specific entry point for secondary CPUs.
+ */
+ENTRY(ox820_secondary_startup)
+ mov r4, #0
+ /* invalidate both caches and branch target cache */
+ mcr p15, 0, r4, c7, c7, 0
+ /*
+ * we've been released from the holding pen: secondary_stack
+ * should now contain the SVC stack for this core
+ */
+ b secondary_startup
diff --git a/arch/arm/mach-oxnas/hotplug.c b/arch/arm/mach-oxnas/hotplug.c
new file mode 100644
index 0000000..18fa814
--- /dev/null
+++ b/arch/arm/mach-oxnas/hotplug.c
@@ -0,0 +1,111 @@
+/*
+ * linux/arch/arm/mach-oxnas/hotplug.c
+ *
+ * Copyright (C) 2002 ARM Ltd.
+ * All Rights Reserved
+ *
+ * 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/kernel.h>
+#include <linux/errno.h>
+#include <linux/smp.h>
+
+#include <asm/cp15.h>
+#include <asm/smp_plat.h>
+
+static inline void cpu_enter_lowpower(void)
+{
+ unsigned int v;
+
+ asm volatile(
+ " mcr p15, 0, %1, c7, c5, 0\n"
+ " mcr p15, 0, %1, c7, c10, 4\n"
+ /*
+ * Turn off coherency
+ */
+ " mrc p15, 0, %0, c1, c0, 1\n"
+ " bic %0, %0, #0x20\n"
+ " mcr p15, 0, %0, c1, c0, 1\n"
+ " mrc p15, 0, %0, c1, c0, 0\n"
+ " bic %0, %0, %2\n"
+ " mcr p15, 0, %0, c1, c0, 0\n"
+ : "=&r" (v)
+ : "r" (0), "Ir" (CR_C)
+ : "cc");
+}
+
+static inline void cpu_leave_lowpower(void)
+{
+ unsigned int v;
+
+ asm volatile( "mrc p15, 0, %0, c1, c0, 0\n"
+ " orr %0, %0, %1\n"
+ " mcr p15, 0, %0, c1, c0, 0\n"
+ " mrc p15, 0, %0, c1, c0, 1\n"
+ " orr %0, %0, #0x20\n"
+ " mcr p15, 0, %0, c1, c0, 1\n"
+ : "=&r" (v)
+ : "Ir" (CR_C)
+ : "cc");
+}
+
+static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
+{
+ /*
+ * there is no power-control hardware on this platform, so all
+ * we can do is put the core into WFI; this is safe as the calling
+ * code will have already disabled interrupts
+ */
+ for (;;) {
+ /*
+ * here's the WFI
+ */
+ asm(".word 0xe320f003\n"
+ :
+ :
+ : "memory", "cc");
+
+ if (pen_release == cpu_logical_map(cpu)) {
+ /*
+ * OK, proper wakeup, we're done
+ */
+ break;
+ }
+
+ /*
+ * Getting here, means that we have come out of WFI without
+ * having been woken up - this shouldn't happen
+ *
+ * Just note it happening - when we're woken, we can report
+ * its occurrence.
+ */
+ (*spurious)++;
+ }
+}
+
+/*
+ * platform-specific code to shutdown a CPU
+ *
+ * Called with IRQs disabled
+ */
+void ox820_cpu_die(unsigned int cpu)
+{
+ int spurious = 0;
+
+ /*
+ * we're ready for shutdown now, so do it
+ */
+ cpu_enter_lowpower();
+ platform_do_lowpower(cpu, &spurious);
+
+ /*
+ * bring this CPU back into the world of cache
+ * coherency, and then restore interrupts
+ */
+ cpu_leave_lowpower();
+
+ if (spurious)
+ pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
+}
diff --git a/arch/arm/mach-oxnas/platsmp.c b/arch/arm/mach-oxnas/platsmp.c
new file mode 100644
index 0000000..d2ff2c4
--- /dev/null
+++ b/arch/arm/mach-oxnas/platsmp.c
@@ -0,0 +1,161 @@
+/*
+ * arch/arm/mach-oxnas/platsmp.c
+ *
+ * Copyright (C) 2016 Neil Armstrong <narmstrong at baylibre.com>
+ * Copyright (C) 2013 Ma Haijun <mahaijuns at gmail.com>
+ * Copyright (C) 2002 ARM Ltd.
+ * All Rights Reserved
+ *
+ * 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/io.h>
+#include <linux/delay.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#include <asm/cacheflush.h>
+#include <asm/cp15.h>
+#include <asm/smp_plat.h>
+#include <asm/smp_scu.h>
+
+extern void ox820_secondary_startup(void);
+extern void ox820_cpu_die(unsigned int cpu);
+
+static DEFINE_SPINLOCK(boot_lock);
+
+static void __iomem *cpu_ctrl;
+static void __iomem *gic_cpu_ctrl;
+
+#define HOLDINGPEN_CPU_OFFSET 0xc8
+#define HOLDINGPEN_LOCATION_OFFSET 0xc4
+
+#define GIC_NCPU_OFFSET(cpu) (0x100 + (cpu)*0x100)
+#define GIC_CPU_CTRL 0x00
+#define GIC_CPU_CTRL_ENABLE 1
+
+static inline void write_pen_release(int val)
+{
+ writel(val, cpu_ctrl + HOLDINGPEN_CPU_OFFSET);
+}
+
+static inline int read_pen_release(void)
+{
+ return readl(cpu_ctrl + HOLDINGPEN_CPU_OFFSET);
+}
+
+void ox820_secondary_init(unsigned int cpu)
+{
+ /*
+ * let the primary processor know we're out of the
+ * pen, then head off into the C entry point
+ */
+ write_pen_release(-1);
+
+ /*
+ * Synchronise with the boot thread.
+ */
+ spin_lock(&boot_lock);
+ spin_unlock(&boot_lock);
+}
+
+int ox820_boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+ unsigned long timeout;
+
+ /*
+ * Set synchronisation state between this boot processor
+ * and the secondary one
+ */
+ spin_lock(&boot_lock);
+
+ /*
+ * This is really belt and braces; we hold unintended secondary
+ * CPUs in the holding pen until we're ready for them. However,
+ * since we haven't sent them a soft interrupt, they shouldn't
+ * be there.
+ */
+ write_pen_release(cpu);
+
+ /*
+ * Enable GIC cpu interface in CPU Interface Control Register
+ */
+ writel(GIC_CPU_CTRL_ENABLE,
+ gic_cpu_ctrl + GIC_NCPU_OFFSET(cpu) + GIC_CPU_CTRL);
+
+ /*
+ * Send the secondary CPU a soft interrupt, thereby causing
+ * the boot monitor to read the system wide flags register,
+ * and branch to the address found there.
+ */
+
+ arch_send_wakeup_ipi_mask(cpumask_of(cpu));
+ timeout = jiffies + (1 * HZ);
+ while (time_before(jiffies, timeout)) {
+ smp_rmb();
+ if (read_pen_release() == -1)
+ break;
+
+ udelay(10);
+ }
+
+ /*
+ * now the secondary core is starting up let it run its
+ * calibrations, then wait for it to finish
+ */
+ spin_unlock(&boot_lock);
+
+ return read_pen_release() != -1 ? -ENOSYS : 0;
+}
+
+static void __init ox820_smp_prepare_cpus(unsigned int max_cpus)
+{
+ struct device_node *np;
+ void __iomem *scu_base;
+
+ np = of_find_compatible_node(NULL, NULL, "arm,arm11mp-scu");
+ scu_base = of_iomap(np, 0);
+ of_node_put(np);
+ if (!scu_base)
+ return;
+
+ /* Remap CPU Interrupt Interface Registers */
+ np = of_find_compatible_node(NULL, NULL, "arm,arm11mp-gic");
+ gic_cpu_ctrl = of_iomap(np, 1);
+ of_node_put(np);
+ if (!gic_cpu_ctrl)
+ goto unmap_scu;
+
+ np = of_find_compatible_node(NULL, NULL, "oxsemi,ox820-sys-ctrl");
+ cpu_ctrl = of_iomap(np, 0);
+ of_node_put(np);
+ if (!cpu_ctrl)
+ goto unmap_scu;
+
+ scu_enable(scu_base);
+ flush_cache_all();
+
+ /*
+ * Write the address of secondary startup into the
+ * system-wide flags register. The BootMonitor waits
+ * until it receives a soft interrupt, and then the
+ * secondary CPU branches to this address.
+ */
+ writel(virt_to_phys(ox820_secondary_startup),
+ cpu_ctrl + HOLDINGPEN_LOCATION_OFFSET);
+
+unmap_scu:
+ iounmap(scu_base);
+}
+
+static const struct smp_operations ox820_smp_ops __initconst = {
+ .smp_prepare_cpus = ox820_smp_prepare_cpus,
+ .smp_secondary_init = ox820_secondary_init,
+ .smp_boot_secondary = ox820_boot_secondary,
+#ifdef CONFIG_HOTPLUG_CPU
+ .cpu_die = ox820_cpu_die,
+#endif
+};
+
+CPU_METHOD_OF_DECLARE(ox820_smp, "oxsemi,ox820-smp", &ox820_smp_ops);
--
2.7.0
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