Date:   Fri, 17 Jan 2020 08:33:27 +0800
From:   Jiaxun Yang <jiaxun.yang@...goat.com>
To:     周琰杰 (Zhou Yanjie) 
        <zhouyanjie@...yeetech.com>,
        "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "mips-creator-ci20-dev@...glegroups.com" 
        <mips-creator-ci20-dev@...glegroups.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "paul.burton@...s.com" <paul.burton@...s.com>,
        "paulburton@...nel.org" <paulburton@...nel.org>,
        "jhogan@...nel.org" <jhogan@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "syq@...ian.org" <syq@...ian.org>,
        "ralf@...ux-mips.org" <ralf@...ux-mips.org>,
        "rick.tyliu@...enic.com" <rick.tyliu@...enic.com>,
        "jason@...edaemon.net" <jason@...edaemon.net>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "geert+renesas@...der.be" <geert+renesas@...der.be>,
        "krzk@...nel.org" <krzk@...nel.org>,
        "paul@...pouillou.net" <paul@...pouillou.net>,
        "prasannatsmkumar@...il.com" <prasannatsmkumar@...il.com>,
        "sernia.zhou@...mail.com" <sernia.zhou@...mail.com>,
        "zhenwenjin@...il.com" <zhenwenjin@...il.com>,
        "ebiederm@...ssion.com" <ebiederm@...ssion.com>,
        "hns@...delico.com" <hns@...delico.com>,
        "paul@...die.org.uk" <paul@...die.org.uk>
Subject: Re: [PATCH v2 1/6] MIPS: JZ4780: Introduce SMP support.



17.01.2020, 02:35, "周琰杰 (Zhou Yanjie)" <zhouyanjie@...yeetech.com>:
> Forward port smp support from kernel 3.18.3 of CI20_linux
> to upstream kernel 5.5.
>
> Tested-by: H. Nikolaus Schaller <hns@...delico.com>
> Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@...yeetech.com>
> ---
>
> Notes:
>     v1-v2:
>     1.Remove 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.

Thanks for your enhancements, see my comments below. 

>
>  arch/mips/include/asm/mach-jz4740/jz4780-smp.h | 98 ++++++++
>  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 | 305 +++++++++++++++++++++++++
>  arch/mips/kernel/idle.c | 14 +-
>  7 files changed, 485 insertions(+), 1 deletion(-)
>  create mode 100644 arch/mips/include/asm/mach-jz4740/jz4780-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/jz4780-smp.h b/arch/mips/include/asm/mach-jz4740/jz4780-smp.h
> new file mode 100644
> index 00000000..9ed693e
> --- /dev/null
> +++ b/arch/mips/include/asm/mach-jz4740/jz4780-smp.h
> @@ -0,0 +1,98 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (C) 2013, Paul Burton <paul.burton@...tec.com>
> + * 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)
> +
> +/*
> + * CPM Low Power Control register
> + */
> +#define CPM_LPCR 0xb0000004

Still a little bit dirty, but looks better. I'd prefer a SMP node.

> +#define CPM_LPCR_PDSCPU (_ULCAST_(1) << 31)

BIT(31)?

> +#define CPM_LPCR_SCPUS (_ULCAST_(1) << 27)
> +
> +#ifdef CONFIG_SMP
> +
> +extern void jz4780_smp_wait_irqoff(void);
> +
> +extern void jz4780_smp_init(void);
> +extern void jz4780_secondary_cpu_entry(void);
> +
> +#else /* !CONFIG_SMP */
> +
> +static inline void jz4780_smp_init(void) { }
> +
> +#endif /* !CONFIG_SMP */
> +
> +#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..a79159e 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/jz4780-smp.h>
>
>  void __init prom_init(void)
>  {
>          fw_init_cmdline();
> +#if defined(CONFIG_MACH_JZ4780) && defined(CONFIG_SMP)
> + jz4780_smp_init();
> +#endif
>  }
>
>  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@...tec.com>
> + * 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..35ec839
> --- /dev/null
> +++ b/arch/mips/jz4740/smp.c
> @@ -0,0 +1,305 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2013, Paul Burton <paul.burton@...tec.com>
> + * 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/jz4780-smp.h>
> +#include <asm/r4kcache.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;
> +
> +static DEFINE_SPINLOCK(smp_lock);
> +
> +extern void (*r4k_blast_dcache)(void);
> +

We've got that define in r4kcache.h

> +/*
> + * 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();
> +}
> +
> +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);
> + }
> +
> + /* 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 struct irqaction mbox_action = {
> + .handler = mbox_handler,
> + .name = "core mailbox",
> + .flags = IRQF_PERCPU | IRQF_NO_THREAD,
> +};
> +
> +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 */
> + setup_irq(MIPS_CPU_IRQ_BASE + 3, &mbox_action);
> +
> + init_cpu_present(cpu_possible_mask);
> +
> + ctrl = read_c0_corectrl();
> +
> + for (cpu = 0; cpu < max_cpus; cpu++) {
> + /* use reset entry point from REIM register */
> + ctrl |= CORECTRL_RPC0 << cpu;
> + }
> +
> + for_each_compatible_node(cpu_node, NULL, "ingenic,xburst") {

for_each_of_cpu_node better?

> + err = of_property_read_u32_index(cpu_node, "reg", 0, &cpu);

of_cpu_node_to_id?

> + if (err) {
> + 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;
> + unsigned timeout;
> + 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]);
> +
> + /* power up the core */
> + {
> + outl(inl(CPM_LPCR) & ~CPM_LPCR_PDSCPU, CPM_LPCR);
> + /* wait for the CPU to be powered up */
> + timeout = 100;
> + while (inl(CPM_LPCR) & CPM_LPCR_SCPUS) {

readl/writel? inl is used for PIO rather than MMIO.

> + if (timeout) {
> + timeout--;
> + udelay(10);
> + continue;
> + }
> +
> + pr_err("CPU%u: Wait for power up timeout\n", 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;
> + 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)
> +{
> + register_smp_ops(&jz4780_smp_ops);
> +}
> diff --git a/arch/mips/kernel/idle.c b/arch/mips/kernel/idle.c
> index 37f8e78..a406de3 100644
> --- a/arch/mips/kernel/idle.c
> +++ b/arch/mips/kernel/idle.c
> @@ -19,6 +19,10 @@
>  #include <asm/idle.h>
>  #include <asm/mipsregs.h>
>
> +#ifdef CONFIG_MACH_JZ4780
> +# include <asm/mach-jz4740/jz4780-smp.h>
> +#endif
> +
>  /*
>   * Not all of the MIPS CPUs have the "wait" instruction available. Moreover,
>   * the implementation of the "wait" feature differs between CPU families. This
> @@ -172,7 +176,6 @@ 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 +249,15 @@ void __init check_wait(void)
>                     cpu_wait = r4k_wait;
>                   */
>                  break;
> + case CPU_XBURST:
> +#if defined(CONFIG_MACH_JZ4780) && defined(CONFIG_SMP)
> + if (NR_CPUS > 1)
> + cpu_wait = jz4780_smp_wait_irqoff;
> + else
> + cpu_wait = r4k_wait;
> +#else
> + cpu_wait = r4k_wait;
> +#endif
>          default:
>                  break;
>          }
> --
> 2.7.4

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