U-Boot

// SPDX-License-Identifier: GPL-2.0+
/*
 * Socfpga Reset Controller Driver
 *
 * Copyright 2014 Steffen Trumtrar <s.trumtrar@pengutronix.de>
 *
 * based on
 * Allwinner SoCs Reset Controller driver
 *
 * Copyright 2013 Maxime Ripard
 *
 * Maxime Ripard <maxime.ripard@free-electrons.com>
 */

#include <dm.h>
#include <log.h>
#include <malloc.h>
#include <dm/lists.h>
#include <dm/of_access.h>
#include <env.h>
#include <reset-uclass.h>
#include <wait_bit.h>
#include <linux/bitops.h>
#include <linux/io.h>
#include <linux/sizes.h>
#include <linux/kconfig.h>

#define BANK_INCREMENT		4
#define NR_BANKS		8

struct socfpga_reset_data {
	void __iomem *modrst_base;
};

/*
 * For compatibility with Kernels that don't support peripheral reset, this
 * driver can keep the old behaviour of not asserting peripheral reset before
 * starting the OS and deasserting all peripheral resets (enabling all
 * peripherals).
 *
 * For that, the reset driver checks the environment variable
 * "socfpga_legacy_reset_compat". If this variable is '1', perihperals are not
 * reset again once taken out of reset and all peripherals in 'permodrst' are
 * taken out of reset before booting into the OS.
 * Note that this should be required for gen5 systems only that are running
 * Linux kernels without proper peripheral reset support for all drivers used.
 */
static bool socfpga_reset_keep_enabled(void)
{
#if !defined(CONFIG_XPL_BUILD) || CONFIG_IS_ENABLED(ENV_SUPPORT)
	const char *env_str;
	long val;

	env_str = env_get("socfpga_legacy_reset_compat");
	if (env_str) {
		val = simple_strtol(env_str, NULL, 0);
		if (val == 1)
			return true;
	}
#endif

	return false;
}

static int socfpga_reset_assert(struct reset_ctl *reset_ctl)
{
	struct socfpga_reset_data *data = dev_get_priv(reset_ctl->dev);
	int id = reset_ctl->id;
	int reg_width = sizeof(u32);
	int bank = id / (reg_width * BITS_PER_BYTE);
	int offset = id % (reg_width * BITS_PER_BYTE);

	setbits_le32(data->modrst_base + (bank * BANK_INCREMENT), BIT(offset));
	return 0;
}

static int socfpga_reset_deassert(struct reset_ctl *reset_ctl)
{
	struct socfpga_reset_data *data = dev_get_priv(reset_ctl->dev);
	int id = reset_ctl->id;
	int reg_width = sizeof(u32);
	int bank = id / (reg_width * BITS_PER_BYTE);
	int offset = id % (reg_width * BITS_PER_BYTE);

	clrbits_le32(data->modrst_base + (bank * BANK_INCREMENT), BIT(offset));

	return wait_for_bit_le32(data->modrst_base + (bank * BANK_INCREMENT),
				 BIT(offset),
				 false, 500, false);
}

static const struct reset_ops socfpga_reset_ops = {
	.rst_assert = socfpga_reset_assert,
	.rst_deassert = socfpga_reset_deassert,
};

static int socfpga_reset_probe(struct udevice *dev)
{
	struct socfpga_reset_data *data = dev_get_priv(dev);
	u32 modrst_offset;
	void __iomem *membase;

	membase = dev_read_addr_ptr(dev);

	modrst_offset = dev_read_u32_default(dev, "altr,modrst-offset", 0x10);
	data->modrst_base = membase + modrst_offset;

	return 0;
}

static int socfpga_reset_remove(struct udevice *dev)
{
	struct socfpga_reset_data *data = dev_get_priv(dev);

	if (socfpga_reset_keep_enabled()) {
		puts("Deasserting all peripheral resets\n");
		writel(0, data->modrst_base + 4);
		if (IS_ENABLED(CONFIG_TARGET_SOCFPGA_ARRIA10))
			writel(0, data->modrst_base + 8);
	}

	return 0;
}

static int socfpga_reset_bind(struct udevice *dev)
{
	int ret;
	struct udevice *sys_child;

	/*
	 * The sysreset driver does not have a device node, so bind it here.
	 * Bind it to the node, too, so that it can get its base address.
	 */
	ret = device_bind_driver_to_node(dev, "socfpga_sysreset", "sysreset",
					 dev_ofnode(dev), &sys_child);
	if (ret)
		debug("Warning: No sysreset driver: ret=%d\n", ret);

	return 0;
}

static const struct udevice_id socfpga_reset_match[] = {
	{ .compatible = "altr,rst-mgr" },
	{ /* sentinel */ },
};

U_BOOT_DRIVER(socfpga_reset) = {
	.name = "socfpga-reset",
	.id = UCLASS_RESET,
	.of_match = socfpga_reset_match,
	.bind = socfpga_reset_bind,
	.probe = socfpga_reset_probe,
	.priv_auto	= sizeof(struct socfpga_reset_data),
	.ops = &socfpga_reset_ops,
	.remove = socfpga_reset_remove,
	.flags	= DM_FLAG_OS_PREPARE,
};