cregit-Linux how code gets into the kernel

Release 4.9 arch/arm/mach-shmobile/platsmp-apmu.c

/*
 * SMP support for SoCs with APMU
 *
 * Copyright (C) 2014  Renesas Electronics Corporation
 * Copyright (C) 2013  Magnus Damm
 *
 * 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/cpu_pm.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/of_address.h>
#include <linux/smp.h>
#include <linux/suspend.h>
#include <linux/threads.h>
#include <asm/cacheflush.h>
#include <asm/cp15.h>
#include <asm/proc-fns.h>
#include <asm/smp_plat.h>
#include <asm/suspend.h>
#include "common.h"
#include "platsmp-apmu.h"
#include "rcar-gen2.h"

static struct {
	
void __iomem *iomem;
	
int bit;
} 
apmu_cpus[NR_CPUS];


#define WUPCR_OFFS 0x10

#define PSTR_OFFS 0x40

#define CPUNCR_OFFS(n) (0x100 + (0x10 * (n)))


static int __maybe_unused apmu_power_on(void __iomem *p, int bit) { /* request power on */ writel_relaxed(BIT(bit), p + WUPCR_OFFS); /* wait for APMU to finish */ while (readl_relaxed(p + WUPCR_OFFS) != 0) ; return 0; }

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static int __maybe_unused apmu_power_off(void __iomem *p, int bit) { /* request Core Standby for next WFI */ writel_relaxed(3, p + CPUNCR_OFFS(bit)); return 0; }

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static int __maybe_unused apmu_power_off_poll(void __iomem *p, int bit) { int k; for (k = 0; k < 1000; k++) { if (((readl_relaxed(p + PSTR_OFFS) >> (bit * 4)) & 0x03) == 3) return 1; mdelay(1); } return 0; }

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static int __maybe_unused apmu_wrap(int cpu, int (*fn)(void __iomem *p, int cpu)) { void __iomem *p = apmu_cpus[cpu].iomem; return p ? fn(p, apmu_cpus[cpu].bit) : -EINVAL; }

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#ifdef CONFIG_SMP
static void apmu_init_cpu(struct resource *res, int cpu, int bit) { if ((cpu >= ARRAY_SIZE(apmu_cpus)) || apmu_cpus[cpu].iomem) return; apmu_cpus[cpu].iomem = ioremap_nocache(res->start, resource_size(res)); apmu_cpus[cpu].bit = bit; pr_debug("apmu ioremap %d %d %pr\n", cpu, bit, res); }

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static void apmu_parse_cfg(void (*fn)(struct resource *res, int cpu, int bit), struct rcar_apmu_config *apmu_config, int num) { int id; int k; int bit, index; bool is_allowed; for (k = 0; k < num; k++) { /* only enable the cluster that includes the boot CPU */ is_allowed = false; for (bit = 0; bit < ARRAY_SIZE(apmu_config[k].cpus); bit++) { id = apmu_config[k].cpus[bit]; if (id >= 0) { if (id == cpu_logical_map(0)) is_allowed = true; } } if (!is_allowed) continue; for (bit = 0; bit < ARRAY_SIZE(apmu_config[k].cpus); bit++) { id = apmu_config[k].cpus[bit]; if (id >= 0) { index = get_logical_index(id); if (index >= 0) fn(&apmu_config[k].iomem, index, bit); } } } }

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static const struct of_device_id apmu_ids[] = { { .compatible = "renesas,apmu" }, { /*sentinel*/ } };
static void apmu_parse_dt(void (*fn)(struct resource *res, int cpu, int bit)) { struct device_node *np_apmu, *np_cpu; struct resource res; int bit, index; u32 id; for_each_matching_node(np_apmu, apmu_ids) { /* only enable the cluster that includes the boot CPU */ bool is_allowed = false; for (bit = 0; bit < CONFIG_NR_CPUS; bit++) { np_cpu = of_parse_phandle(np_apmu, "cpus", bit); if (np_cpu) { if (!of_property_read_u32(np_cpu, "reg", &id)) { if (id == cpu_logical_map(0)) { is_allowed = true; of_node_put(np_cpu); break; } } of_node_put(np_cpu); } } if (!is_allowed) continue; for (bit = 0; bit < CONFIG_NR_CPUS; bit++) { np_cpu = of_parse_phandle(np_apmu, "cpus", bit); if (np_cpu) { if (!of_property_read_u32(np_cpu, "reg", &id)) { index = get_logical_index(id); if ((index >= 0) && !of_address_to_resource(np_apmu, 0, &res)) fn(&res, index, bit); } of_node_put(np_cpu); } } } }

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static void __init shmobile_smp_apmu_setup_boot(void) { /* install boot code shared by all CPUs */ shmobile_boot_fn = virt_to_phys(shmobile_smp_boot); }

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void __init shmobile_smp_apmu_prepare_cpus(unsigned int max_cpus, struct rcar_apmu_config *apmu_config, int num) { shmobile_smp_apmu_setup_boot(); apmu_parse_cfg(apmu_init_cpu, apmu_config, num); }

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int shmobile_smp_apmu_boot_secondary(unsigned int cpu, struct task_struct *idle) { /* For this particular CPU register boot vector */ shmobile_smp_hook(cpu, virt_to_phys(secondary_startup), 0); return apmu_wrap(cpu, apmu_power_on); }

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static void __init shmobile_smp_apmu_prepare_cpus_dt(unsigned int max_cpus) { shmobile_smp_apmu_setup_boot(); apmu_parse_dt(apmu_init_cpu); rcar_gen2_pm_init(); }

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static int shmobile_smp_apmu_boot_secondary_md21(unsigned int cpu, struct task_struct *idle) { /* Error out when hardware debug mode is enabled */ if (rcar_gen2_read_mode_pins() & BIT(21)) { pr_warn("Unable to boot CPU%u when MD21 is set\n", cpu); return -ENOTSUPP; } return shmobile_smp_apmu_boot_secondary(cpu, idle); }

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static struct smp_operations apmu_smp_ops __initdata = { .smp_prepare_cpus = shmobile_smp_apmu_prepare_cpus_dt, .smp_boot_secondary = shmobile_smp_apmu_boot_secondary_md21, #ifdef CONFIG_HOTPLUG_CPU .cpu_can_disable = shmobile_smp_cpu_can_disable, .cpu_die = shmobile_smp_apmu_cpu_die, .cpu_kill = shmobile_smp_apmu_cpu_kill, #endif }; CPU_METHOD_OF_DECLARE(shmobile_smp_apmu, "renesas,apmu", &apmu_smp_ops); #endif /* CONFIG_SMP */ #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_SUSPEND) /* nicked from arch/arm/mach-exynos/hotplug.c */
static inline void cpu_enter_lowpower_a15(void) { unsigned int v; asm volatile( " mrc p15, 0, %0, c1, c0, 0\n" " bic %0, %0, %1\n" " mcr p15, 0, %0, c1, c0, 0\n" : "=&r" (v) : "Ir" (CR_C) : "cc"); flush_cache_louis(); asm volatile( /* * Turn off coherency */ " mrc p15, 0, %0, c1, c0, 1\n" " bic %0, %0, %1\n" " mcr p15, 0, %0, c1, c0, 1\n" : "=&r" (v) : "Ir" (0x40) : "cc"); isb(); dsb(); }

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static void shmobile_smp_apmu_cpu_shutdown(unsigned int cpu) { /* Select next sleep mode using the APMU */ apmu_wrap(cpu, apmu_power_off); /* Do ARM specific CPU shutdown */ cpu_enter_lowpower_a15(); }

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static inline void cpu_leave_lowpower(void) { unsigned int v; asm volatile("mrc p15, 0, %0, c1, c0, 0\n" " orr %0, %0, %1\n" " mcr p15, 0, %0, c1, c0, 0\n" " mrc p15, 0, %0, c1, c0, 1\n" " orr %0, %0, %2\n" " mcr p15, 0, %0, c1, c0, 1\n" : "=&r" (v) : "Ir" (CR_C), "Ir" (0x40) : "cc"); }

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#endif #if defined(CONFIG_HOTPLUG_CPU)
void shmobile_smp_apmu_cpu_die(unsigned int cpu) { /* For this particular CPU deregister boot vector */ shmobile_smp_hook(cpu, 0, 0); /* Shutdown CPU core */ shmobile_smp_apmu_cpu_shutdown(cpu); /* jump to shared mach-shmobile sleep / reset code */ shmobile_smp_sleep(); }

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int shmobile_smp_apmu_cpu_kill(unsigned int cpu) { return apmu_wrap(cpu, apmu_power_off_poll); }

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#endif #if defined(CONFIG_SUSPEND)
static int shmobile_smp_apmu_do_suspend(unsigned long cpu) { shmobile_smp_hook(cpu, virt_to_phys(cpu_resume), 0); shmobile_smp_apmu_cpu_shutdown(cpu); cpu_do_idle(); /* WFI selects Core Standby */ return 1; }

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static int shmobile_smp_apmu_enter_suspend(suspend_state_t state) { cpu_suspend(smp_processor_id(), shmobile_smp_apmu_do_suspend); cpu_leave_lowpower(); return 0; }

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void __init shmobile_smp_apmu_suspend_init(void) { shmobile_suspend_ops.enter = shmobile_smp_apmu_enter_suspend; }

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#endif

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