Re: [PATCH v6 2/7] MIPS: JZ4780: Introduce SMP support.

From: Paul Cercueil
Date: Thu Feb 20 2020 - 13:28:04 EST

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In reply to: åçæ (Zhou Yanjie): "[PATCH v6 2/7] MIPS: JZ4780: Introduce SMP support."
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Hi Zhou,

Le ven., fÃvr. 21, 2020 at 00:24, åçæ (Zhou Yanjie) <zhouyanjie@xxxxxxxxxxxxxx> a Ãcrit :

Forward port smp support from kernel 3.18.3 of CI20_linux
to upstream kernel 5.6.

Tested-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>
Tested-by: Paul Boddie <paul@xxxxxxxxxxxxx>
Signed-off-by: åçæ (Zhou Yanjie) <zhouyanjie@xxxxxxxxxxxxxx>
Reviewed-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
---

Notes:
v1->v2:
1.Remove unnecessary "plat_irq_dispatch(void)" in irq-ingenic.c.
2.Add a timeout check for "jz4780_boot_secondary()" to avoid a dead loop.
3.Replace hard code in smp.c with macro.

v2->v3:
1.Remove unnecessary "extern void (*r4k_blast_dcache)(void)" in smp.c.
2.Use "for_each_of_cpu_node" instead "for_each_compatible_node" in smp.c.
3.Use "of_cpu_node_to_id" instead "of_property_read_u32_index" in smp.c.
4.Move LCR related operations to jz4780-cgu.c.

v3->v4:
Rebase on top of kernel 5.6-rc1.

v4->v5:
1.Splitting changes involving "jz4780-cgu.c" into separate commit.
2.Use "request_irq()" replace "setup_irq()".

v5->v6:
In order to have a kernel that works on multiple SoCs at the same
time, use "IS_ENABLED()" replace "#ifdef".

arch/mips/include/asm/mach-jz4740/smp.h | 81 ++++++++++
arch/mips/jz4740/Kconfig | 3 +
arch/mips/jz4740/Makefile | 5 +
arch/mips/jz4740/prom.c | 4 +
arch/mips/jz4740/smp-entry.S | 57 +++++++
arch/mips/jz4740/smp.c | 254 ++++++++++++++++++++++++++++++++
arch/mips/kernel/idle.c | 36 ++++-
7 files changed, 439 insertions(+), 1 deletion(-)
create mode 100644 arch/mips/include/asm/mach-jz4740/smp.h
create mode 100644 arch/mips/jz4740/smp-entry.S
create mode 100644 arch/mips/jz4740/smp.c

diff --git a/arch/mips/include/asm/mach-jz4740/smp.h b/arch/mips/include/asm/mach-jz4740/smp.h
new file mode 100644
index 00000000..af3c21b
--- /dev/null
+++ b/arch/mips/include/asm/mach-jz4740/smp.h
@@ -0,0 +1,81 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2013, Paul Burton <paul.burton@xxxxxxxxxx>
+ * JZ4780 SMP definitions
+ */
+
+#ifndef __MIPS_ASM_MACH_JZ4740_JZ4780_SMP_H__
+#define __MIPS_ASM_MACH_JZ4740_JZ4780_SMP_H__
+
+#define read_c0_corectrl() __read_32bit_c0_register($12, 2)
+#define write_c0_corectrl(val) __write_32bit_c0_register($12, 2, val)
+
+#define read_c0_corestatus() __read_32bit_c0_register($12, 3)
+#define write_c0_corestatus(val) __write_32bit_c0_register($12, 3, val)
+
+#define read_c0_reim() __read_32bit_c0_register($12, 4)
+#define write_c0_reim(val) __write_32bit_c0_register($12, 4, val)
+
+#define read_c0_mailbox0() __read_32bit_c0_register($20, 0)
+#define write_c0_mailbox0(val) __write_32bit_c0_register($20, 0, val)
+
+#define read_c0_mailbox1() __read_32bit_c0_register($20, 1)
+#define write_c0_mailbox1(val) __write_32bit_c0_register($20, 1, val)
+
+#define smp_clr_pending(mask) do { \
+ unsigned int stat; \
+ stat = read_c0_corestatus(); \
+ stat &= ~((mask) & 0xff); \
+ write_c0_corestatus(stat); \
+ } while (0)
+
+/*
+ * Core Control register
+ */
+#define CORECTRL_SLEEP1M_SHIFT 17
+#define CORECTRL_SLEEP1M (_ULCAST_(0x1) << CORECTRL_SLEEP1M_SHIFT)
+#define CORECTRL_SLEEP0M_SHIFT 16
+#define CORECTRL_SLEEP0M (_ULCAST_(0x1) << CORECTRL_SLEEP0M_SHIFT)
+#define CORECTRL_RPC1_SHIFT 9
+#define CORECTRL_RPC1 (_ULCAST_(0x1) << CORECTRL_RPC1_SHIFT)
+#define CORECTRL_RPC0_SHIFT 8
+#define CORECTRL_RPC0 (_ULCAST_(0x1) << CORECTRL_RPC0_SHIFT)
+#define CORECTRL_SWRST1_SHIFT 1
+#define CORECTRL_SWRST1 (_ULCAST_(0x1) << CORECTRL_SWRST1_SHIFT)
+#define CORECTRL_SWRST0_SHIFT 0
+#define CORECTRL_SWRST0 (_ULCAST_(0x1) << CORECTRL_SWRST0_SHIFT)
+
+/*
+ * Core Status register
+ */
+#define CORESTATUS_SLEEP1_SHIFT 17
+#define CORESTATUS_SLEEP1 (_ULCAST_(0x1) << CORESTATUS_SLEEP1_SHIFT)
+#define CORESTATUS_SLEEP0_SHIFT 16
+#define CORESTATUS_SLEEP0 (_ULCAST_(0x1) << CORESTATUS_SLEEP0_SHIFT)
+#define CORESTATUS_IRQ1P_SHIFT 9
+#define CORESTATUS_IRQ1P (_ULCAST_(0x1) << CORESTATUS_IRQ1P_SHIFT)
+#define CORESTATUS_IRQ0P_SHIFT 8
+#define CORESTATUS_IRQ0P (_ULCAST_(0x1) << CORESTATUS_IRQ8P_SHIFT)
+#define CORESTATUS_MIRQ1P_SHIFT 1
+#define CORESTATUS_MIRQ1P (_ULCAST_(0x1) << CORESTATUS_MIRQ1P_SHIFT)
+#define CORESTATUS_MIRQ0P_SHIFT 0
+#define CORESTATUS_MIRQ0P (_ULCAST_(0x1) << CORESTATUS_MIRQ0P_SHIFT)
+
+/*
+ * Reset Entry & IRQ Mask register
+ */
+#define REIM_ENTRY_SHIFT 16
+#define REIM_ENTRY (_ULCAST_(0xffff) << REIM_ENTRY_SHIFT)
+#define REIM_IRQ1M_SHIFT 9
+#define REIM_IRQ1M (_ULCAST_(0x1) << REIM_IRQ1M_SHIFT)
+#define REIM_IRQ0M_SHIFT 8
+#define REIM_IRQ0M (_ULCAST_(0x1) << REIM_IRQ0M_SHIFT)
+#define REIM_MBOXIRQ1M_SHIFT 1
+#define REIM_MBOXIRQ1M (_ULCAST_(0x1) << REIM_MBOXIRQ1M_SHIFT)
+#define REIM_MBOXIRQ0M_SHIFT 0
+#define REIM_MBOXIRQ0M (_ULCAST_(0x1) << REIM_MBOXIRQ0M_SHIFT)
+
+extern void jz4780_smp_init(void);
+extern void jz4780_secondary_cpu_entry(void);
+
+#endif /* __MIPS_ASM_MACH_JZ4740_JZ4780_SMP_H__ */
diff --git a/arch/mips/jz4740/Kconfig b/arch/mips/jz4740/Kconfig
index 412d2fa..0239597 100644
--- a/arch/mips/jz4740/Kconfig
+++ b/arch/mips/jz4740/Kconfig
@@ -34,9 +34,12 @@ config MACH_JZ4770

config MACH_JZ4780
bool
+ select GENERIC_CLOCKEVENTS_BROADCAST if SMP
select MIPS_CPU_SCACHE
+ select NR_CPUS_DEFAULT_2
select SYS_HAS_CPU_MIPS32_R2
select SYS_SUPPORTS_HIGHMEM
+ select SYS_SUPPORTS_SMP

config MACH_X1000
bool
diff --git a/arch/mips/jz4740/Makefile b/arch/mips/jz4740/Makefile
index 6de14c0..0a0f024 100644
--- a/arch/mips/jz4740/Makefile
+++ b/arch/mips/jz4740/Makefile
@@ -12,3 +12,8 @@ CFLAGS_setup.o = -I$(src)/../../../scripts/dtc/libfdt
# PM support

obj-$(CONFIG_PM) += pm.o
+
+# SMP support
+
+obj-$(CONFIG_SMP) += smp.o
+obj-$(CONFIG_SMP) += smp-entry.o
diff --git a/arch/mips/jz4740/prom.c b/arch/mips/jz4740/prom.c
index ff4555c..026259e 100644
--- a/arch/mips/jz4740/prom.c
+++ b/arch/mips/jz4740/prom.c
@@ -8,10 +8,14 @@

#include <asm/bootinfo.h>
#include <asm/fw/fw.h>
+#include <asm/mach-jz4740/smp.h>

void __init prom_init(void)
{
fw_init_cmdline();
+
+ if (IS_ENABLED(CONFIG_MACH_JZ4780) && IS_ENABLED(CONFIG_SMP))
+ jz4780_smp_init();

I guess it's OK for a first version, but SMP should really be decoupled from the SoC version. A SMP-enabled kernel should be able to also support non-SMP SoCs.

}

void __init prom_free_prom_memory(void)
diff --git a/arch/mips/jz4740/smp-entry.S b/arch/mips/jz4740/smp-entry.S
new file mode 100644
index 00000000..20049a3
--- /dev/null
+++ b/arch/mips/jz4740/smp-entry.S
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2013, Paul Burton <paul.burton@xxxxxxxxxx>
+ * JZ4780 SMP entry point
+ */
+
+#include <asm/addrspace.h>
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/cacheops.h>
+#include <asm/mipsregs.h>
+
+#define CACHE_SIZE (32 * 1024)
+#define CACHE_LINESIZE 32
+
+.extern jz4780_cpu_entry_sp
+.extern jz4780_cpu_entry_gp
+
+.section .text.smp-entry
+.balign 0x10000
+.set noreorder
+LEAF(jz4780_secondary_cpu_entry)
+ mtc0 zero, CP0_CAUSE
+
+ li t0, ST0_CU0
+ mtc0 t0, CP0_STATUS
+
+ /* cache setup */
+ li t0, KSEG0
+ ori t1, t0, CACHE_SIZE
+ mtc0 zero, CP0_TAGLO, 0
+1: cache Index_Store_Tag_I, 0(t0)
+ cache Index_Store_Tag_D, 0(t0)
+ bne t0, t1, 1b
+ addiu t0, t0, CACHE_LINESIZE
+
+ /* kseg0 cache attribute */
+ mfc0 t0, CP0_CONFIG, 0
+ ori t0, t0, CONF_CM_CACHABLE_NONCOHERENT
+ mtc0 t0, CP0_CONFIG, 0
+
+ /* pagemask */
+ mtc0 zero, CP0_PAGEMASK, 0
+
+ /* retrieve sp */
+ la t0, jz4780_cpu_entry_sp
+ lw sp, 0(t0)
+
+ /* retrieve gp */
+ la t0, jz4780_cpu_entry_gp
+ lw gp, 0(t0)
+
+ /* jump to the kernel in kseg0 */
+ la t0, smp_bootstrap
+ jr t0
+ nop
+ END(jz4780_secondary_cpu_entry)
diff --git a/arch/mips/jz4740/smp.c b/arch/mips/jz4740/smp.c
new file mode 100644
index 00000000..5fe0cf3
--- /dev/null
+++ b/arch/mips/jz4740/smp.c
@@ -0,0 +1,254 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013, Paul Burton <paul.burton@xxxxxxxxxx>
+ * JZ4780 SMP
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/of.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <linux/smp.h>
+#include <linux/tick.h>
+#include <asm/mach-jz4740/smp.h>
+#include <asm/smp-ops.h>
+
+static struct clk *cpu_clock_gates[CONFIG_NR_CPUS] = { NULL };
+
+u32 jz4780_cpu_entry_sp;
+u32 jz4780_cpu_entry_gp;
+
+static struct cpumask cpu_running;

This is not used anywhere, is it?

+
+static DEFINE_SPINLOCK(smp_lock);
+
+static irqreturn_t mbox_handler(int irq, void *dev_id)
+{
+ int cpu = smp_processor_id();
+ u32 action, status;
+
+ spin_lock(&smp_lock);
+
+ switch (cpu) {
+ case 0:
+ action = read_c0_mailbox0();
+ write_c0_mailbox0(0);
+ break;
+ case 1:
+ action = read_c0_mailbox1();
+ write_c0_mailbox1(0);
+ break;
+ default:
+ panic("unhandled cpu %d!", cpu);

XBurst has 4 mailboxes, maybe add them here?

+ }
+
+ /* clear pending mailbox interrupt */
+ status = read_c0_corestatus();
+ status &= ~(CORESTATUS_MIRQ0P << cpu);
+ write_c0_corestatus(status);
+
+ spin_unlock(&smp_lock);
+
+ if (action & SMP_RESCHEDULE_YOURSELF)
+ scheduler_ipi();
+ if (action & SMP_CALL_FUNCTION)
+ generic_smp_call_function_interrupt();
+
+ return IRQ_HANDLED;
+}
+
+static void jz4780_smp_setup(void)
+{
+ u32 addr, reim;
+ int cpu;
+
+ reim = read_c0_reim();
+
+ for (cpu = 0; cpu < NR_CPUS; cpu++) {
+ __cpu_number_map[cpu] = cpu;
+ __cpu_logical_map[cpu] = cpu;
+ set_cpu_possible(cpu, true);
+ }
+
+ /* mask mailbox interrupts for this core */
+ reim &= ~REIM_MBOXIRQ0M;
+ write_c0_reim(reim);
+
+ /* clear mailboxes & pending mailbox IRQs */
+ write_c0_mailbox0(0);
+ write_c0_mailbox1(0);
+ write_c0_corestatus(0);
+
+ /* set reset entry point */
+ addr = KSEG1ADDR((u32)&jz4780_secondary_cpu_entry);
+ WARN_ON(addr & ~REIM_ENTRY);
+ reim &= ~REIM_ENTRY;
+ reim |= addr & REIM_ENTRY;
+
+ /* unmask mailbox interrupts for this core */
+ reim |= REIM_MBOXIRQ0M;
+ write_c0_reim(reim);
+ set_c0_status(STATUSF_IP3);
+ irq_enable_hazard();
+
+ cpumask_set_cpu(cpu, &cpu_running);
+}
+
+static void jz4780_smp_prepare_cpus(unsigned int max_cpus)
+{
+ struct device_node *cpu_node;
+ unsigned cpu, ctrl;
+ int err;
+
+ /* setup the mailbox IRQ */
+ err = request_irq(MIPS_CPU_IRQ_BASE + 3, mbox_handler,
+ IRQF_PERCPU | IRQF_NO_THREAD, "core mailbox", NULL);
+ if (err)
+ pr_err("request_irq() on core mailbox failed\n");
+
+ init_cpu_present(cpu_possible_mask);

jz4780_smp_setup() marks CPUs 0..NR_CPUS as possible, NR_CPUS being a config option that can be anywhere between 2 and 256. This basically says that up to 256 CPUs are actually present.

+
+ ctrl = read_c0_corectrl();
+
+ for (cpu = 0; cpu < max_cpus; cpu++) {
+ /* use reset entry point from REIM register */
+ ctrl |= CORECTRL_RPC0 << cpu;

max_cpus is just NR_CPUS, so this does not work. You should move this in the "for_each_of_cpu_node" below.

+ }
+
+ for_each_of_cpu_node(cpu_node) {
+ cpu = of_cpu_node_to_id(cpu_node);
+ if (cpu < 0) {
+ pr_err("Failed to read index of %s\n",
+ cpu_node->full_name);
+ continue;
+ }
+
+ cpu_clock_gates[cpu] = of_clk_get(cpu_node, 0);
+ if (IS_ERR(cpu_clock_gates[cpu])) {
+ cpu_clock_gates[cpu] = NULL;
+ continue;
+ }
+
+ err = clk_prepare(cpu_clock_gates[cpu]);
+ if (err)
+ pr_err("Failed to prepare CPU clock gate\n");
+ }
+
+ write_c0_corectrl(ctrl);
+}
+
+static int jz4780_boot_secondary(int cpu, struct task_struct *idle)
+{
+ unsigned long flags;
+ u32 ctrl;
+
+ spin_lock_irqsave(&smp_lock, flags);
+
+ /* ensure the core is in reset */
+ ctrl = read_c0_corectrl();
+ ctrl |= CORECTRL_SWRST0 << cpu;
+ write_c0_corectrl(ctrl);
+
+ /* ungate core clock */
+ if (cpu_clock_gates[cpu])
+ clk_enable(cpu_clock_gates[cpu]);
+
+ /* set entry sp/gp register values */
+ jz4780_cpu_entry_sp = __KSTK_TOS(idle);
+ jz4780_cpu_entry_gp = (u32)task_thread_info(idle);
+ smp_wmb();
+
+ /* take the core out of reset */
+ ctrl &= ~(CORECTRL_SWRST0 << cpu);
+ write_c0_corectrl(ctrl);
+
+ cpumask_set_cpu(cpu, &cpu_running);
+
+ spin_unlock_irqrestore(&smp_lock, flags);
+
+ return 0;
+}
+
+static void jz4780_init_secondary(void)
+{
+}
+
+static void jz4780_smp_finish(void)
+{
+ u32 reim;
+
+ spin_lock(&smp_lock);
+
+ /* unmask mailbox interrupts for this core */
+ reim = read_c0_reim();
+ reim |= REIM_MBOXIRQ0M << smp_processor_id();
+ write_c0_reim(reim);
+
+ spin_unlock(&smp_lock);
+
+ /* unmask interrupts for this core */
+ change_c0_status(ST0_IM, STATUSF_IP3 | STATUSF_IP2 |
+ STATUSF_IP1 | STATUSF_IP0);
+ irq_enable_hazard();
+
+ /* force broadcast timer */
+ tick_broadcast_force();
+}
+
+static void jz4780_send_ipi_single_locked(int cpu, unsigned int action)
+{
+ u32 mbox;
+
+ switch (cpu) {
+ case 0:
+ mbox = read_c0_mailbox0();
+ write_c0_mailbox0(mbox | action);
+ break;
+ case 1:
+ mbox = read_c0_mailbox1();
+ write_c0_mailbox1(mbox | action);
+ break;

Same as above - there are 4 mailboxes.

+ default:
+ panic("unhandled cpu %d!", cpu);
+ }
+}
+
+static void jz4780_send_ipi_single(int cpu, unsigned int action)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&smp_lock, flags);
+ jz4780_send_ipi_single_locked(cpu, action);
+ spin_unlock_irqrestore(&smp_lock, flags);
+}
+
+static void jz4780_send_ipi_mask(const struct cpumask *mask,
+ unsigned int action)
+{
+ unsigned long flags;
+ int cpu;
+
+ spin_lock_irqsave(&smp_lock, flags);
+
+ for_each_cpu(cpu, mask)
+ jz4780_send_ipi_single_locked(cpu, action);
+
+ spin_unlock_irqrestore(&smp_lock, flags);
+}
+
+static struct plat_smp_ops jz4780_smp_ops = {
+ .send_ipi_single = jz4780_send_ipi_single,
+ .send_ipi_mask = jz4780_send_ipi_mask,
+ .init_secondary = jz4780_init_secondary,
+ .smp_finish = jz4780_smp_finish,
+ .boot_secondary = jz4780_boot_secondary,
+ .smp_setup = jz4780_smp_setup,
+ .prepare_cpus = jz4780_smp_prepare_cpus,
+};
+
+void jz4780_smp_init(void)

This one can be marked __init.

+{
+ register_smp_ops(&jz4780_smp_ops);
+}
diff --git a/arch/mips/kernel/idle.c b/arch/mips/kernel/idle.c
index 37f8e78..a3afd98 100644
--- a/arch/mips/kernel/idle.c
+++ b/arch/mips/kernel/idle.c
@@ -18,6 +18,7 @@
#include <asm/cpu-type.h>
#include <asm/idle.h>
#include <asm/mipsregs.h>
+#include <asm/r4kcache.h>

/*
* Not all of the MIPS CPUs have the "wait" instruction available. Moreover,
@@ -88,6 +89,34 @@ static void __cpuidle rm7k_wait_irqoff(void)
}

/*
+ * The Ingenic jz4780 SMP variant has to write back dirty cache lines before
+ * executing wait. The CPU & cache clock will be gated until we return from
+ * the wait, and if another core attempts to access data from our data cache
+ * during this time then it will lock up.
+ */
+void jz4780_smp_wait_irqoff(void)
+{
+ unsigned long pending = read_c0_cause() & read_c0_status() & CAUSEF_IP;
+
+ /*
+ * Going to idle has a significant overhead due to the cache flush so
+ * try to avoid it if we'll immediately be woken again due to an IRQ.
+ */
+ if (!need_resched() && !pending) {
+ r4k_blast_dcache();
+
+ __asm__(
+ " .set push \n"
+ " .set mips3 \n"
+ " sync \n"
+ " wait \n"
+ " .set pop \n");
+ }
+
+ local_irq_enable();
+}
+
+/*
* Au1 'wait' is only useful when the 32kHz counter is used as timer,
* since coreclock (and the cp0 counter) stops upon executing it. Only an
* interrupt can wake it, so they must be enabled before entering idle modes.
@@ -172,7 +201,6 @@ void __init check_wait(void)
case CPU_CAVIUM_OCTEON_PLUS:
case CPU_CAVIUM_OCTEON2:
case CPU_CAVIUM_OCTEON3:
- case CPU_XBURST:
case CPU_LOONGSON32:
case CPU_XLR:
case CPU_XLP:
@@ -246,6 +274,12 @@ void __init check_wait(void)
cpu_wait = r4k_wait;
*/
break;
+ case CPU_XBURST:
+ if (IS_ENABLED(CONFIG_MACH_JZ4780) &&
+ IS_ENABLED(CONFIG_SMP) && (NR_CPUS > 1))
+ cpu_wait = jz4780_smp_wait_irqoff;
+ else
+ cpu_wait = r4k_wait;
default:
break;
}
--
2.7.4

Next message: Gustavo A. R. Silva: "Re: [PATCH] IB/core, cache: Replace zero-length array with flexible-array member"
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In reply to: åçæ (Zhou Yanjie): "[PATCH v6 2/7] MIPS: JZ4780: Introduce SMP support."
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