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authorRich Felker <dalias@libc.org>2016-02-15 18:36:13 +0000
committerRich Felker <dalias@libc.org>2016-08-05 03:29:39 +0000
commitb4214e41b7152b1964a3421a40251d202ae2d2c0 (patch)
treeedfab19d4f16bf2d6f42168c6598aa1fac4ac0e3 /arch/sh
parent4b6ef05b3e89f5bdb888fbd5467e996a9193b884 (diff)
sh: add SMP support for J2
Support is hooked up via a cpu start method specified in the device tree, and also depends on DT nodes that describe the interfaces for performing IPI and identifying which cpu execution is taking place on. The currently used method is a form of spin table, where secondary cpus are unblocked by writing to a special address. Signed-off-by: Rich Felker <dalias@libc.org>
Diffstat (limited to 'arch/sh')
-rw-r--r--arch/sh/Kconfig2
-rw-r--r--arch/sh/kernel/cpu/sh2/Makefile4
-rw-r--r--arch/sh/kernel/cpu/sh2/smp-j2.c139
3 files changed, 145 insertions, 0 deletions
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 2ef6f652bc50..ee086958b2b2 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -261,6 +261,8 @@ config CPU_SUBTYPE_SH7619
config CPU_SUBTYPE_J2
bool "Support J2 processor"
select CPU_J2
+ select SYS_SUPPORTS_SMP
+ select GENERIC_CLOCKEVENTS_BROADCAST if SMP
# SH-2A Processor Support
diff --git a/arch/sh/kernel/cpu/sh2/Makefile b/arch/sh/kernel/cpu/sh2/Makefile
index f0f059acfcfb..904c4283d923 100644
--- a/arch/sh/kernel/cpu/sh2/Makefile
+++ b/arch/sh/kernel/cpu/sh2/Makefile
@@ -5,3 +5,7 @@
obj-y := ex.o probe.o entry.o
obj-$(CONFIG_CPU_SUBTYPE_SH7619) += setup-sh7619.o clock-sh7619.o
+
+# SMP setup
+smp-$(CONFIG_CPU_J2) := smp-j2.o
+obj-$(CONFIG_SMP) += $(smp-y)
diff --git a/arch/sh/kernel/cpu/sh2/smp-j2.c b/arch/sh/kernel/cpu/sh2/smp-j2.c
new file mode 100644
index 000000000000..6ccd7e4dc008
--- /dev/null
+++ b/arch/sh/kernel/cpu/sh2/smp-j2.c
@@ -0,0 +1,139 @@
+/*
+ * SMP support for J2 processor
+ *
+ * Copyright (C) 2015-2016 Smart Energy Instruments, Inc.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <asm/cmpxchg.h>
+
+DEFINE_PER_CPU(unsigned, j2_ipi_messages);
+
+extern u32 *sh2_cpuid_addr;
+static u32 *j2_ipi_trigger;
+static int j2_ipi_irq;
+
+static irqreturn_t j2_ipi_interrupt_handler(int irq, void *arg)
+{
+ unsigned cpu = hard_smp_processor_id();
+ volatile unsigned *pmsg = &per_cpu(j2_ipi_messages, cpu);
+ unsigned messages, i;
+
+ do messages = *pmsg;
+ while (cmpxchg(pmsg, messages, 0) != messages);
+
+ if (!messages) return IRQ_NONE;
+
+ for (i=0; i<SMP_MSG_NR; i++)
+ if (messages & (1U<<i))
+ smp_message_recv(i);
+
+ return IRQ_HANDLED;
+}
+
+static void j2_smp_setup(void)
+{
+}
+
+static void j2_prepare_cpus(unsigned int max_cpus)
+{
+ struct device_node *np;
+ unsigned i, max = 1;
+
+ np = of_find_compatible_node(NULL, NULL, "jcore,ipi-controller");
+ if (!np)
+ goto out;
+
+ j2_ipi_irq = irq_of_parse_and_map(np, 0);
+ j2_ipi_trigger = of_iomap(np, 0);
+ if (!j2_ipi_irq || !j2_ipi_trigger)
+ goto out;
+
+ np = of_find_compatible_node(NULL, NULL, "jcore,cpuid-mmio");
+ if (!np)
+ goto out;
+
+ sh2_cpuid_addr = of_iomap(np, 0);
+ if (!sh2_cpuid_addr)
+ goto out;
+
+ if (request_irq(j2_ipi_irq, j2_ipi_interrupt_handler, IRQF_PERCPU,
+ "ipi", (void *)j2_ipi_interrupt_handler) != 0)
+ goto out;
+
+ max = max_cpus;
+out:
+ /* Disable any cpus past max_cpus, or all secondaries if we didn't
+ * get the necessary resources to support SMP. */
+ for (i=max; i<NR_CPUS; i++) {
+ set_cpu_possible(i, false);
+ set_cpu_present(i, false);
+ }
+}
+
+static void j2_start_cpu(unsigned int cpu, unsigned long entry_point)
+{
+ struct device_node *np;
+ u32 regs[2];
+ void __iomem *release, *initpc;
+
+ if (!cpu) return;
+
+ np = of_get_cpu_node(cpu, NULL);
+ if (!np) return;
+
+ if (of_property_read_u32_array(np, "cpu-release-addr", regs, 2)) return;
+ release = ioremap_nocache(regs[0], sizeof(u32));
+ initpc = ioremap_nocache(regs[1], sizeof(u32));
+
+ __raw_writel(entry_point, initpc);
+ __raw_writel(1, release);
+
+ iounmap(initpc);
+ iounmap(release);
+
+ pr_info("J2 SMP: requested start of cpu %u\n", cpu);
+}
+
+static unsigned int j2_smp_processor_id(void)
+{
+ return __raw_readl(sh2_cpuid_addr);
+}
+
+static void j2_send_ipi(unsigned int cpu, unsigned int message)
+{
+ volatile unsigned *pmsg;
+ unsigned old;
+ unsigned long val;
+
+ /* There is only one IPI interrupt shared by all messages, so
+ * we keep a separate interrupt flag per message type in sw. */
+ pmsg = &per_cpu(j2_ipi_messages, cpu);
+ do old = *pmsg;
+ while (cmpxchg(pmsg, old, old|(1U<<message)) != old);
+
+ /* Generate the actual interrupt by writing to CCRn bit 28. */
+ val = __raw_readl(j2_ipi_trigger + cpu);
+ __raw_writel(val | (1U<<28), j2_ipi_trigger + cpu);
+}
+
+static struct plat_smp_ops j2_smp_ops = {
+ .smp_setup = j2_smp_setup,
+ .prepare_cpus = j2_prepare_cpus,
+ .start_cpu = j2_start_cpu,
+ .smp_processor_id = j2_smp_processor_id,
+ .send_ipi = j2_send_ipi,
+ .cpu_die = native_cpu_die,
+ .cpu_disable = native_cpu_disable,
+ .play_dead = native_play_dead,
+};
+
+CPU_METHOD_OF_DECLARE(j2_cpu_method, "jcore,spin-table", &j2_smp_ops);