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Date: Fri, 28 Feb 2020 00:17:45 +0800
From: Zhou Yanjie <zhouyanjie@...yeetech.com>
To: Paul Cercueil <paul@...pouillou.net>
Cc: linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
tglx@...utronix.de, ralf@...ux-mips.org, paulburton@...nel.org,
jiaxun.yang@...goat.com, chenhc@...ote.com, sboyd@...nel.org,
mturquette@...libre.com, mark.rutland@....com, robh+dt@...nel.org,
daniel.lezcano@...aro.org, geert+renesas@...der.be,
krzk@...nel.org, ebiederm@...ssion.com, miquel.raynal@...tlin.com,
keescook@...omium.org, sernia.zhou@...mail.com,
zhenwenjin@...il.com, dongsheng.qiu@...enic.com
Subject: Re: [PATCH v6 2/7] MIPS: JZ4780: Introduce SMP support.
Hi Paul,
On 2020年02月21日 02:27, Paul Cercueil wrote:
> Hi Zhou,
>
>
> Le ven., févr. 21, 2020 at 00:24, 周琰杰 (Zhou Yanjie)
> <zhouyanjie@...yeetech.com> a écrit :
>> Forward port smp support from kernel 3.18.3 of CI20_linux
>> to upstream kernel 5.6.
>>
>> Tested-by: H. Nikolaus Schaller <hns@...delico.com>
>> Tested-by: Paul Boddie <paul@...die.org.uk>
>> Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@...yeetech.com>
>> Reviewed-by: Jiaxun Yang <jiaxun.yang@...goat.com>
>> ---
>>
>> 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@...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)
>> +
>> +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.
>
OK, will change in next version.
>
>> }
>>
>> 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..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@...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/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?
>
It is used in "cpumask_set_cpu".
>> +
>> +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?
>
Sure.
>> + }
>> +
>> + /* 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.
>
I will change it in next version.
>> +
>> + 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.
>
Sure.
>> + }
>> +
>> + 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.
>
Sure.
>> + 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.
>
Sure.
>> +{
>> + 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
>>
>
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