[PATCH] CNS3xxx: Add SMP support
Krzysztof Hałasa
khalasa at piap.pl
Thu May 10 03:41:35 PDT 2018
Signed-off-by: Krzysztof Hałasa <khalasa at piap.pl>
--- a/arch/arm/mach-cns3xxx/Kconfig
+++ b/arch/arm/mach-cns3xxx/Kconfig
@@ -3,6 +3,9 @@ menuconfig ARCH_CNS3XXX
bool "Cavium Networks CNS3XXX family"
depends on ARCH_MULTI_V6
select ARM_GIC
+ select HAVE_ARM_SCU if SMP
+ select HAVE_ARM_TWD
+ select HAVE_SMP
help
Support for Cavium Networks CNS3XXX platform.
--- a/arch/arm/mach-cns3xxx/Makefile
+++ b/arch/arm/mach-cns3xxx/Makefile
@@ -4,3 +4,4 @@ cns3xxx-y += core.o pm.o
cns3xxx-$(CONFIG_ATAGS) += devices.o
cns3xxx-$(CONFIG_PCI) += pcie.o
cns3xxx-$(CONFIG_MACH_CNS3420VB) += cns3420vb.o
+cns3xxx-$(CONFIG_SMP) += platsmp.o headsmp.o
--- a/arch/arm/mach-cns3xxx/cns3420vb.c
+++ b/arch/arm/mach-cns3xxx/cns3420vb.c
@@ -251,5 +251,6 @@ MACHINE_START(CNS3420VB, "Cavium Networks CNS3420 Validation Board")
.init_time = cns3xxx_timer_init,
.init_machine = cns3420_init,
.init_late = cns3xxx_pcie_init_late,
+ .smp = smp_ops(cns3xxx_smp_ops),
.restart = cns3xxx_restart,
MACHINE_END
--- a/arch/arm/mach-cns3xxx/core.c
+++ b/arch/arm/mach-cns3xxx/core.c
@@ -17,6 +17,7 @@
#include <linux/platform_device.h>
#include <linux/usb/ehci_pdriver.h>
#include <linux/usb/ohci_pdriver.h>
+#include <asm/smp_twd.h>
#include <asm/mach/arch.h>
#include <asm/mach/map.h>
#include <asm/mach/time.h>
@@ -26,6 +27,8 @@
#include "core.h"
#include "pm.h"
+#define IRQ_LOCALTIMER 29
+
static struct map_desc cns3xxx_io_desc[] __initdata = {
{
.virtual = CNS3XXX_TC11MP_SCU_BASE_VIRT,
@@ -198,6 +201,15 @@ static struct irqaction cns3xxx_timer_irq = {
.handler = cns3xxx_timer_interrupt,
};
+static void __init cns3xxx_init_twd(void)
+{
+ static DEFINE_TWD_LOCAL_TIMER(cns3xx_twd_local_timer,
+ CNS3XXX_TC11MP_TWD_BASE,
+ IRQ_LOCALTIMER);
+
+ twd_local_timer_register(&cns3xx_twd_local_timer);
+}
+
/*
* Set up the clock source and clock events devices
*/
@@ -251,6 +263,7 @@ static void __init __cns3xxx_timer_init(unsigned int timer_irq)
setup_irq(timer_irq, &cns3xxx_timer_irq);
cns3xxx_clockevents_init(timer_irq);
+ cns3xxx_init_twd();
}
void __init cns3xxx_timer_init(void)
--- a/arch/arm/mach-cns3xxx/core.h
+++ b/arch/arm/mach-cns3xxx/core.h
@@ -13,6 +13,7 @@
#include <linux/reboot.h>
+extern struct smp_operations cns3xxx_smp_ops;
extern void cns3xxx_timer_init(void);
#ifdef CONFIG_CACHE_L2X0
--- /dev/null
+++ b/arch/arm/mach-cns3xxx/headsmp.S
@@ -0,0 +1,39 @@
+/*
+ * Cloned from linux/arch/arm/mach-exynos/headsmp.S
+ *
+ * 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>
+
+/*
+ * CNS3XXX specific entry point for secondary CPUs. This provides
+ * a "holding pen" into which all secondary cores are held until we're
+ * ready for them to initialise.
+ */
+ENTRY(cns3xxx_secondary_startup)
+ mrc p15, 0, r0, c0, c0, 5
+ and r0, r0, #15
+ adr r4, 1f
+ ldmia r4, {r5, r6}
+ sub r4, r4, r5
+ add r6, r6, r4
+pen: ldr r7, [r6]
+ cmp r7, r0
+ bne pen
+
+ /*
+ * we've been released from the holding pen: secondary_stack
+ * should now contain the SVC stack for this core
+ */
+ b secondary_startup
+ENDPROC(cns3xxx_secondary_startup)
+
+ .align 2
+1: .long .
+ .long pen_release
--- /dev/null
+++ b/arch/arm/mach-cns3xxx/platsmp.c
@@ -0,0 +1,151 @@
+/*
+ * linux/arch/arm/mach-cns3xxx/platsmp.c
+ *
+ * Copyright (C) 2002 ARM Ltd.
+ * Copyright 2012 Gateworks Corporation
+ * Chris Lang <clang at gateworks.com>
+ * Tim Harvey <tharvey at gateworks.com>
+ *
+ * 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/init.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/jiffies.h>
+#include <linux/smp.h>
+#include <linux/io.h>
+#include <asm/cacheflush.h>
+#include <asm/smp_scu.h>
+#include <asm/unified.h>
+#include "cns3xxx.h"
+
+extern void cns3xxx_secondary_startup(void);
+
+#define SCU_CPU_STATUS 0x08
+#define SCU_BASE ((void __iomem *)CNS3XXX_TC11MP_SCU_BASE_VIRT)
+
+/*
+ * Write pen_release in a way that is guaranteed to be visible to all
+ * observers, irrespective of whether they're taking part in coherency
+ * or not. This is necessary for the hotplug code to work reliably.
+ */
+static void write_pen_release(int val)
+{
+ pen_release = val;
+ smp_wmb();
+ __cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release));
+ outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1));
+}
+
+static DEFINE_SPINLOCK(boot_lock);
+
+static void cns3xxx_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);
+}
+
+static int cns3xxx_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);
+
+ /*
+ * The secondary processor is waiting to be released from
+ * the holding pen - release it, then wait for it to flag
+ * that it has been released by resetting pen_release.
+ *
+ * Note that "pen_release" is the hardware CPU ID, whereas
+ * "cpu" is Linux's internal ID.
+ */
+ write_pen_release(cpu);
+
+ /*
+ * 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 (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 pen_release != -1 ? -ENOSYS : 0;
+}
+
+/*
+ * Initialise the CPU possible map early - this describes the CPUs
+ * which may be present or become present in the system.
+ */
+static void __init cns3xxx_smp_init_cpus(void)
+{
+ unsigned int i, ncores;
+ unsigned int status;
+
+ /* SCU_CPU_STATUS must be examined instead of SCU_CONFIGURATION
+ * used in scu_get_core_count
+ */
+ status = __raw_readl(SCU_BASE + SCU_CPU_STATUS);
+ for (i = 0; i < NR_CPUS + 1; i++) {
+ if (((status >> (i * 2)) & 0x3) == 0)
+ set_cpu_possible(i, true);
+ else
+ break;
+ }
+ ncores = i;
+}
+
+static void __init cns3xxx_smp_prepare_cpus(unsigned int max_cpus)
+{
+ /*
+ * enable SCU
+ */
+ scu_enable(SCU_BASE);
+
+ /*
+ * Write the address of secondary startup into the
+ * system-wide flags register. The boot monitor waits
+ * until it receives a soft interrupt, and then the
+ * secondary CPU branches to this address.
+ */
+ __raw_writel(virt_to_phys(cns3xxx_secondary_startup),
+ (void __iomem *)(CNS3XXX_MISC_BASE_VIRT + 0x0600));
+}
+
+struct smp_operations cns3xxx_smp_ops __initdata = {
+ .smp_init_cpus = cns3xxx_smp_init_cpus,
+ .smp_prepare_cpus = cns3xxx_smp_prepare_cpus,
+ .smp_secondary_init = cns3xxx_secondary_init,
+ .smp_boot_secondary = cns3xxx_boot_secondary,
+};
--
Krzysztof Halasa
Industrial Research Institute for Automation and Measurements PIAP
Al. Jerozolimskie 202, 02-486 Warsaw, Poland
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