u-boot/drivers/watchdog/atcwdt200_wdt.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C)  2023 Andes Technology Corporation.
 *
 */

#include <asm/io.h>
#include <dm.h>
#include <hang.h>
#include <linux/bitops.h>
#include <wdt.h>

#define NODE_NOT_FOUND     0xFFFFFFFF

#define WDT_WP_MAGIC       0x5aa5
#define WDT_RESTART_MAGIC  0xcafe

/* Control Register */
#define REG_WDT_ID         0x00
#define REG_WDT_CFG        0x10
#define REG_WDT_RS         0x14
#define REG_WDT_WE         0x18
#define REG_WDT_STA        0x1C

#define RST_TIME_OFF       8
#define RST_TIME_MSK       (0x7 << RST_TIME_OFF)
#define RST_CLK_128        (0 << RST_TIME_OFF)
#define RST_CLK_256        (1 << RST_TIME_OFF)
#define RST_CLK_512        (2 << RST_TIME_OFF)
#define RST_CLK_1024       (3 << RST_TIME_OFF)
#define INT_TIME_OFF       4
#define INT_TIME_MSK       (0xf << INT_TIME_OFF)
#define INT_CLK_2_6        (0 << INT_TIME_OFF)  /* clk period*2^6  */
#define INT_CLK_2_8        (1 << INT_TIME_OFF)  /* clk period*2^8  */
#define INT_CLK_2_10       (2 << INT_TIME_OFF)  /* clk period*2^10 */
#define INT_CLK_2_11       (3 << INT_TIME_OFF)  /* clk period*2^11 */
#define INT_CLK_2_12       (4 << INT_TIME_OFF)  /* clk period*2^12 */
#define INT_CLK_2_13       (5 << INT_TIME_OFF)  /* clk period*2^13 */
#define INT_CLK_2_14       (6 << INT_TIME_OFF)  /* clk period*2^14 */
#define INT_CLK_2_15       (7 << INT_TIME_OFF)  /* clk period*2^15 */
#define INT_CLK_2_17       (8 << INT_TIME_OFF)  /* clk period*2^17 */
#define INT_CLK_2_19       (9 << INT_TIME_OFF)  /* clk period*2^19 */
#define INT_CLK_2_21       (10 << INT_TIME_OFF) /* clk period*2^21 */
#define INT_CLK_2_23       (11 << INT_TIME_OFF) /* clk period*2^23 */
#define INT_CLK_2_25       (12 << INT_TIME_OFF) /* clk period*2^25 */
#define INT_CLK_2_27       (13 << INT_TIME_OFF) /* clk period*2^27 */
#define INT_CLK_2_29       (14 << INT_TIME_OFF) /* clk period*2^29 */
#define INT_CLK_2_31       (15 << INT_TIME_OFF) /* clk period*2^31 */
#define INT_CLK_MIN        0x0
#define INT_CLK_MAX_16B    0x7
#define INT_CLK_MAX_32B    0xF
#define RST_EN             BIT(3)
#define INT_EN             BIT(2)
#define CLK_PCLK           BIT(1)
#define WDT_EN             BIT(0)
#define INT_EXPIRED        BIT(0)

#define INT_TIME_ARRAY     16
#define RST_TIME_ARRAY     8

struct wdt_priv {
	void __iomem *base;
	u32 wdt_clk_src;
	u32 clk_freq;
	u8  max_clk;
};

static inline u8 atcwdt_get_2_power_of_n(u8 index, u8 type)
{
	const u8 div_int[INT_TIME_ARRAY] = {6, 8, 10, 11, 12, 13, 14, 15,
					    17, 19, 21, 23, 25, 27, 29, 31};
	const u8 div_rst[RST_TIME_ARRAY] = {7, 8, 9, 10, 11, 12, 13, 14};
	const u8 *pdiv;

	if (type == RST_TIME_ARRAY)
		pdiv = div_rst;
	else
		pdiv = div_int;

	if (index >= type)
		index = type - 1;

	return pdiv[index];
}

static u8 atcwdt_search_msb(u64 freq_ms, u8 type)
{
	u64 result;
	u64 freq_sec;
	u8 index;

	freq_sec = freq_ms / 1000;
	for (index = 0; index < type; index++) {
		result = freq_sec >> atcwdt_get_2_power_of_n(index, type);

		if (result <= 1)
			break;
	}

	return index;
}

static int atcwdt_wdt_start(struct udevice *dev, u64 timeout, ulong flags)
{
	struct wdt_priv *priv = dev_get_priv(dev);
	u64 rst_max_count;
	u32 rst_max_time_ms;
	u64 rst_time_ms;
	u64 int_time_ms;
	u8  rst_time;
	u8  int_time;

	rst_max_count = 1 << atcwdt_get_2_power_of_n(RST_TIME_ARRAY, RST_TIME_ARRAY);
	rst_max_time_ms = (rst_max_count * 1000) / priv->clk_freq;

	if (timeout > rst_max_time_ms) {
		int_time_ms = timeout - rst_max_time_ms;
		rst_time_ms = rst_max_time_ms;
	} else {
		int_time_ms = 0;
		rst_time_ms = timeout;
	}

	rst_time = atcwdt_search_msb(rst_time_ms * priv->clk_freq, RST_TIME_ARRAY);

	if (int_time_ms) {
		int_time = atcwdt_search_msb(int_time_ms * priv->clk_freq, INT_TIME_ARRAY);
		if (int_time > priv->max_clk)
			int_time = priv->max_clk;
	} else {
		int_time = 0;
	}

	writel(WDT_WP_MAGIC, priv->base + REG_WDT_WE);
	writel(((rst_time << RST_TIME_OFF) & RST_TIME_MSK) | ((int_time << INT_TIME_OFF) &
		INT_TIME_MSK) | INT_EN | RST_EN | priv->wdt_clk_src | WDT_EN,
		priv->base + REG_WDT_CFG);

	return 0;
}

static int atcwdt_wdt_stop(struct udevice *dev)
{
	struct wdt_priv *priv = dev_get_priv(dev);

	writel(WDT_WP_MAGIC, priv->base + REG_WDT_WE);
	writel(0, priv->base + REG_WDT_CFG);

	return 0;
}

static int atcwdt_wdt_restart(struct udevice *dev)
{
	struct wdt_priv *priv = dev_get_priv(dev);

	writel(WDT_WP_MAGIC, priv->base + REG_WDT_WE);
	writel(WDT_RESTART_MAGIC, priv->base + REG_WDT_RS);
	setbits_le32(priv->base + REG_WDT_STA, INT_EXPIRED);

	return 0;
}

static int atcwdt_wdt_expire_now(struct udevice *dev, ulong flags)
{
	atcwdt_wdt_start(dev, 0, 0);
	hang();

	return 0;
}

static int atcwdt_wdt_probe(struct udevice *dev)
{
	struct wdt_priv *priv = dev_get_priv(dev);
	int timer_16bit;

	priv->base = dev_remap_addr_index(dev, 0);
	if (!priv->base)
		return -EFAULT;

	priv->wdt_clk_src = dev_read_u32_default(dev, "clock-source", NODE_NOT_FOUND);
	if (priv->wdt_clk_src == NODE_NOT_FOUND || priv->wdt_clk_src > 1)
		priv->wdt_clk_src = CLK_PCLK;

	timer_16bit = dev_read_u32_default(dev, "16bit_timer", NODE_NOT_FOUND);
	if (timer_16bit == 1 || timer_16bit == NODE_NOT_FOUND)
		priv->max_clk = INT_CLK_MAX_16B;
	else
		priv->max_clk = INT_CLK_MAX_32B;

	priv->clk_freq = dev_read_u32_default(dev, "clock-frequency", NODE_NOT_FOUND);
	if (priv->clk_freq == NODE_NOT_FOUND) {
		printf("atcwdt200: Please provide a valid \"clock-frequency\" in DTB\n");
		return -EINVAL;
	}

	atcwdt_wdt_stop(dev);

	return 0;
}

static const struct wdt_ops atcwdt_wdt_ops = {
	.start = atcwdt_wdt_start,
	.reset = atcwdt_wdt_restart,
	.stop = atcwdt_wdt_stop,
	.expire_now = atcwdt_wdt_expire_now,
};

static const struct udevice_id atcwdt_wdt_ids[] = {
	{.compatible = "andestech,atcwdt200"},
	{}
};

U_BOOT_DRIVER(atcwdt) = {
	.name = "atcwdt200",
	.id = UCLASS_WDT,
	.probe = atcwdt_wdt_probe,
	.of_match = atcwdt_wdt_ids,
	.ops = &atcwdt_wdt_ops,
	.priv_auto = sizeof(struct wdt_priv),
};