1 // SPDX-License-Identifier: GPL-2.0
3 * Watchdog driver for MediaTek SoCs
5 * Copyright (C) 2018 MediaTek Inc.
6 * Author: Ryder Lee <ryder.lee@mediatek.com>
14 #define MTK_WDT_MODE 0x00
15 #define MTK_WDT_LENGTH 0x04
16 #define MTK_WDT_RESTART 0x08
17 #define MTK_WDT_STATUS 0x0c
18 #define MTK_WDT_INTERVAL 0x10
19 #define MTK_WDT_SWRST 0x14
20 #define MTK_WDT_REQ_MODE 0x30
21 #define MTK_WDT_DEBUG_CTL 0x40
23 #define WDT_MODE_KEY (0x22 << 24)
24 #define WDT_MODE_EN BIT(0)
25 #define WDT_MODE_EXTPOL BIT(1)
26 #define WDT_MODE_EXTEN BIT(2)
27 #define WDT_MODE_IRQ_EN BIT(3)
28 #define WDT_MODE_DUAL_EN BIT(6)
30 #define WDT_LENGTH_KEY 0x8
31 #define WDT_LENGTH_TIMEOUT(n) ((n) << 5)
33 #define WDT_RESTART_KEY 0x1971
34 #define WDT_SWRST_KEY 0x1209
40 static int mtk_wdt_reset(struct udevice *dev)
42 struct mtk_wdt_priv *priv = dev_get_priv(dev);
44 /* Reload watchdog duration */
45 writel(WDT_RESTART_KEY, priv->base + MTK_WDT_RESTART);
50 static int mtk_wdt_stop(struct udevice *dev)
52 struct mtk_wdt_priv *priv = dev_get_priv(dev);
54 clrsetbits_le32(priv->base + MTK_WDT_MODE, WDT_MODE_EN, WDT_MODE_KEY);
59 static int mtk_wdt_expire_now(struct udevice *dev, ulong flags)
61 struct mtk_wdt_priv *priv = dev_get_priv(dev);
63 /* Kick watchdog to prevent counter == 0 */
64 writel(WDT_RESTART_KEY, priv->base + MTK_WDT_RESTART);
67 writel(WDT_SWRST_KEY, priv->base + MTK_WDT_SWRST);
73 static void mtk_wdt_set_timeout(struct udevice *dev, u64 timeout_ms)
75 struct mtk_wdt_priv *priv = dev_get_priv(dev);
81 * One WDT_LENGTH count is 512 ticks of the wdt clock
82 * Clock runs at 32768 Hz
83 * e.g. 15.625 ms per count (nominal)
84 * We want the ceiling after dividing timeout_ms by 15.625 ms
85 * We add 15624 prior to the divide to implement the ceiling
86 * We prevent over-flow by clamping the timeout_ms value here
87 * as the maximum WDT_LENGTH counts is 1023 -> 15.984375 sec
88 * We also enforce a minimum of 1 count
89 * Many watchdog peripherals have a self-imposed count of 1
90 * that is added to the register counts.
91 * The MediaTek docs lack details to know if this is the case here.
92 * So we enforce a minimum of 1 to guarantee operation.
94 if (timeout_ms > 15984)
97 timeout_us = timeout_ms * 1000;
98 timeout_cc = (15624 + timeout_us) / 15625;
102 length = WDT_LENGTH_TIMEOUT(timeout_cc) | WDT_LENGTH_KEY;
103 writel(length, priv->base + MTK_WDT_LENGTH);
106 static int mtk_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
108 struct mtk_wdt_priv *priv = dev_get_priv(dev);
110 mtk_wdt_set_timeout(dev, timeout_ms);
114 /* Enable watchdog reset signal */
115 setbits_le32(priv->base + MTK_WDT_MODE,
116 WDT_MODE_EN | WDT_MODE_KEY | WDT_MODE_EXTEN);
121 static int mtk_wdt_probe(struct udevice *dev)
123 struct mtk_wdt_priv *priv = dev_get_priv(dev);
125 priv->base = dev_read_addr_ptr(dev);
130 clrsetbits_le32(priv->base + MTK_WDT_MODE,
131 WDT_MODE_IRQ_EN | WDT_MODE_EXTPOL, WDT_MODE_KEY);
133 return mtk_wdt_stop(dev);
136 static const struct wdt_ops mtk_wdt_ops = {
137 .start = mtk_wdt_start,
138 .reset = mtk_wdt_reset,
139 .stop = mtk_wdt_stop,
140 .expire_now = mtk_wdt_expire_now,
143 static const struct udevice_id mtk_wdt_ids[] = {
144 { .compatible = "mediatek,wdt"},
148 U_BOOT_DRIVER(mtk_wdt) = {
151 .of_match = mtk_wdt_ids,
152 .priv_auto_alloc_size = sizeof(struct mtk_wdt_priv),
153 .probe = mtk_wdt_probe,
155 .flags = DM_FLAG_PRE_RELOC,