ARM: oxnas: Add OX820 SMP support
authorNeil Armstrong <narmstrong@baylibre.com>
Fri, 9 Sep 2016 10:23:11 +0000 (12:23 +0200)
committerNeil Armstrong <narmstrong@baylibre.com>
Wed, 23 Nov 2016 08:53:54 +0000 (09:53 +0100)
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.

Clarifications about Copyrights dates :
- hotplug.c was taken from an old versatile code by Ma Haijun and left verbatim
- headsmp.S was taken from an old versatile code and adapted by Ma Haijun
- platsmp.c is a mix from versatile code, Ma Haijun code and my code for DT
Hence the 2002/2003 ARM Coryrights and 2013 Ma Haijun Copyrights.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
arch/arm/mach-oxnas/Makefile [new file with mode: 0644]
arch/arm/mach-oxnas/headsmp.S [new file with mode: 0644]
arch/arm/mach-oxnas/hotplug.c [new file with mode: 0644]
arch/arm/mach-oxnas/platsmp.c [new file with mode: 0644]

diff --git a/arch/arm/mach-oxnas/Makefile b/arch/arm/mach-oxnas/Makefile
new file mode 100644 (file)
index 0000000..b625906
--- /dev/null
@@ -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 (file)
index 0000000..25fd4f8
--- /dev/null
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2013 Ma Haijun <mahaijuns@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 (file)
index 0000000..854f29b
--- /dev/null
@@ -0,0 +1,109 @@
+/*
+ *  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 (file)
index 0000000..442cc8a
--- /dev/null
@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2016 Neil Armstrong <narmstrong@baylibre.com>
+ * Copyright (C) 2013 Ma Haijun <mahaijuns@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 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
+
+int __init ox820_boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+       /*
+        * 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);
+
+       writel(cpu, cpu_ctrl + HOLDINGPEN_CPU_OFFSET);
+
+       /*
+        * 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));
+
+       return 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();
+
+unmap_scu:
+       iounmap(scu_base);
+}
+
+static const struct smp_operations ox820_smp_ops __initconst = {
+       .smp_prepare_cpus       = ox820_smp_prepare_cpus,
+       .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);