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

/*
 * SMP support for SoCs with APMU
 *
 * 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/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/of_address.h>
#include <linux/smp.h>
#include <asm/cacheflush.h>
#include <asm/cp15.h>
#include <asm/smp_plat.h>
#include <mach/common.h>

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

#define WUPCR_OFFS 0x10
#define PSTR_OFFS 0x40
#define CPUNCR_OFFS(n) (0x100 + (0x10 * (n)))

static int 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;
}

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

static int 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;
}

static int 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;
}

static void apmu_init_cpu(struct resource *res, int cpu, int bit)
{
	if (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 0x%08x 0x%08x\n", cpu, bit,
		 res->start, resource_size(res));
}

static struct {
	struct resource iomem;
	int cpus[4];
} apmu_config[] = {
	{
		.iomem = DEFINE_RES_MEM(0xe6152000, 0x88),
		.cpus = { 0, 1, 2, 3 },
	}
};

static void apmu_parse_cfg(void (*fn)(struct resource *res, int cpu, int bit))
{
	u32 id;
	int k;
	int bit, index;

	for (k = 0; k < ARRAY_SIZE(apmu_config); k++) {
		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);
			}
		}
	}
}

void __init shmobile_smp_apmu_prepare_cpus(unsigned int max_cpus)
{
	/* install boot code shared by all CPUs */
	shmobile_boot_fn = virt_to_phys(shmobile_smp_boot);
	shmobile_boot_arg = MPIDR_HWID_BITMASK;

	/* perform per-cpu setup */
	apmu_parse_cfg(apmu_init_cpu);
}

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(shmobile_invalidate_start), 0);

	return apmu_wrap(cpu, apmu_power_on);
}

#ifdef CONFIG_HOTPLUG_CPU
/* 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();
}

void shmobile_smp_apmu_cpu_die(unsigned int cpu)
{
	/* For this particular CPU deregister boot vector */
	shmobile_smp_hook(cpu, 0, 0);

	/* Select next sleep mode using the APMU */
	apmu_wrap(cpu, apmu_power_off);

	/* Do ARM specific CPU shutdown */
	cpu_enter_lowpower_a15();

	/* jump to shared mach-shmobile sleep / reset code */
	shmobile_smp_sleep();
}

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