u-boot-brain/arch/arm/lib/cache-cp15.c

/*
 * (C) Copyright 2002
 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

#include <common.h>
#include <asm/system.h>
#include <asm/cache.h>
#include <linux/compiler.h>

#if !(defined(CONFIG_SYS_ICACHE_OFF) && defined(CONFIG_SYS_DCACHE_OFF))

DECLARE_GLOBAL_DATA_PTR;

__weak void arm_init_before_mmu(void)
{
}

__weak void arm_init_domains(void)
{
}

static void cp_delay (void)
{
	volatile int i;

	/* copro seems to need some delay between reading and writing */
	for (i = 0; i < 100; i++)
		nop();
	asm volatile("" : : : "memory");
}

void set_section_dcache(int section, enum dcache_option option)
{
	u32 *page_table = (u32 *)gd->arch.tlb_addr;
	u32 value;

	value = (section << MMU_SECTION_SHIFT) | (3 << 10);
	value |= option;
	page_table[section] = value;
}

__weak void mmu_page_table_flush(unsigned long start, unsigned long stop)
{
	debug("%s: Warning: not implemented\n", __func__);
}

void mmu_set_region_dcache_behaviour(u32 start, int size,
				     enum dcache_option option)
{
	u32 *page_table = (u32 *)gd->arch.tlb_addr;
	u32 upto, end;

	end = ALIGN(start + size, MMU_SECTION_SIZE) >> MMU_SECTION_SHIFT;
	start = start >> MMU_SECTION_SHIFT;
	debug("%s: start=%x, size=%x, option=%d\n", __func__, start, size,
	      option);
	for (upto = start; upto < end; upto++)
		set_section_dcache(upto, option);
	mmu_page_table_flush((u32)&page_table[start], (u32)&page_table[end]);
}

__weak void dram_bank_mmu_setup(int bank)
{
	bd_t *bd = gd->bd;
	int	i;

	debug("%s: bank: %d\n", __func__, bank);
	for (i = bd->bi_dram[bank].start >> 20;
	     i < (bd->bi_dram[bank].start >> 20) + (bd->bi_dram[bank].size >> 20);
	     i++) {
#if defined(CONFIG_SYS_ARM_CACHE_WRITETHROUGH)
		set_section_dcache(i, DCACHE_WRITETHROUGH);
#else
		set_section_dcache(i, DCACHE_WRITEBACK);
#endif
	}
}

/* to activate the MMU we need to set up virtual memory: use 1M areas */
static inline void mmu_setup(void)
{
	int i;
	u32 reg;

	arm_init_before_mmu();
	/* Set up an identity-mapping for all 4GB, rw for everyone */
	for (i = 0; i < 4096; i++)
		set_section_dcache(i, DCACHE_OFF);

	for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
		dram_bank_mmu_setup(i);
	}

	/* Copy the page table address to cp15 */
	asm volatile("mcr p15, 0, %0, c2, c0, 0"
		     : : "r" (gd->arch.tlb_addr) : "memory");
	/* Set the access control to all-supervisor */
	asm volatile("mcr p15, 0, %0, c3, c0, 0"
		     : : "r" (~0));

	arm_init_domains();

	/* and enable the mmu */
	reg = get_cr();	/* get control reg. */
	cp_delay();
	set_cr(reg | CR_M);
}

static int mmu_enabled(void)
{
	return get_cr() & CR_M;
}

/* cache_bit must be either CR_I or CR_C */
static void cache_enable(uint32_t cache_bit)
{
	uint32_t reg;

	/* The data cache is not active unless the mmu is enabled too */
	if ((cache_bit == CR_C) && !mmu_enabled())
		mmu_setup();
	reg = get_cr();	/* get control reg. */
	cp_delay();
	set_cr(reg | cache_bit);
}

/* cache_bit must be either CR_I or CR_C */
static void cache_disable(uint32_t cache_bit)
{
	uint32_t reg;

	reg = get_cr();
	cp_delay();

	if (cache_bit == CR_C) {
		/* if cache isn;t enabled no need to disable */
		if ((reg & CR_C) != CR_C)
			return;
		/* if disabling data cache, disable mmu too */
		cache_bit |= CR_M;
	}
	reg = get_cr();
	cp_delay();
	if (cache_bit == (CR_C | CR_M))
		flush_dcache_all();
	set_cr(reg & ~cache_bit);
}
#endif

#ifdef CONFIG_SYS_ICACHE_OFF
void icache_enable (void)
{
	return;
}

void icache_disable (void)
{
	return;
}

int icache_status (void)
{
	return 0;					/* always off */
}
#else
void icache_enable(void)
{
	cache_enable(CR_I);
}

void icache_disable(void)
{
	cache_disable(CR_I);
}

int icache_status(void)
{
	return (get_cr() & CR_I) != 0;
}
#endif

#ifdef CONFIG_SYS_DCACHE_OFF
void dcache_enable (void)
{
	return;
}

void dcache_disable (void)
{
	return;
}

int dcache_status (void)
{
	return 0;					/* always off */
}
#else
void dcache_enable(void)
{
	cache_enable(CR_C);
}

void dcache_disable(void)
{
	cache_disable(CR_C);
}

int dcache_status(void)
{
	return (get_cr() & CR_C) != 0;
}
#endif