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

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

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

/* 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;
}