u-boot/arch/arm/mach-imx/misc.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright 2013 Stefan Roese <sr@denx.de>
 */

#include <common.h>
#include <asm/arch/sys_proto.h>
#include <linux/errno.h>
#include <asm/io.h>
#include <asm/mach-imx/regs-common.h>

DECLARE_GLOBAL_DATA_PTR;

/* 1 second delay should be plenty of time for block reset. */
#define	RESET_MAX_TIMEOUT	1000000

#define	MXS_BLOCK_SFTRST	(1 << 31)
#define	MXS_BLOCK_CLKGATE	(1 << 30)

int mxs_wait_mask_set(struct mxs_register_32 *reg, uint32_t mask, unsigned
								int timeout)
{
	while (--timeout) {
		if ((readl(&reg->reg) & mask) == mask)
			break;
		udelay(1);
	}

	return !timeout;
}

int mxs_wait_mask_clr(struct mxs_register_32 *reg, uint32_t mask, unsigned
								int timeout)
{
	while (--timeout) {
		if ((readl(&reg->reg) & mask) == 0)
			break;
		udelay(1);
	}

	return !timeout;
}

int mxs_reset_block(struct mxs_register_32 *reg)
{
	/* Clear SFTRST */
	writel(MXS_BLOCK_SFTRST, &reg->reg_clr);

	if (mxs_wait_mask_clr(reg, MXS_BLOCK_SFTRST, RESET_MAX_TIMEOUT))
		return 1;

	/* Clear CLKGATE */
	writel(MXS_BLOCK_CLKGATE, &reg->reg_clr);

	/* Set SFTRST */
	writel(MXS_BLOCK_SFTRST, &reg->reg_set);

	/* Wait for CLKGATE being set */
	if (mxs_wait_mask_set(reg, MXS_BLOCK_CLKGATE, RESET_MAX_TIMEOUT))
		return 1;

	/* Clear SFTRST */
	writel(MXS_BLOCK_SFTRST, &reg->reg_clr);

	if (mxs_wait_mask_clr(reg, MXS_BLOCK_SFTRST, RESET_MAX_TIMEOUT))
		return 1;

	/* Clear CLKGATE */
	writel(MXS_BLOCK_CLKGATE, &reg->reg_clr);

	if (mxs_wait_mask_clr(reg, MXS_BLOCK_CLKGATE, RESET_MAX_TIMEOUT))
		return 1;

	return 0;
}

static ulong get_sp(void)
{
	ulong ret;

	asm("mov %0, sp" : "=r"(ret) : );
	return ret;
}

void board_lmb_reserve(struct lmb *lmb)
{
	ulong sp, bank_end;
	int bank;

	sp = get_sp();
	debug("## Current stack ends at 0x%08lx ", sp);

	/* adjust sp by 16K to be safe */
	sp -= 4096 << 2;
	for (bank = 0; bank < CONFIG_NR_DRAM_BANKS; bank++) {
		if (sp < gd->bd->bi_dram[bank].start)
			continue;
		bank_end = gd->bd->bi_dram[bank].start +
			gd->bd->bi_dram[bank].size;
		if (sp >= bank_end)
			continue;
		lmb_reserve(lmb, sp, bank_end - sp);
		break;
	}
}