1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Watchdog driver for MediaTek SoCs
4 *
5 * Copyright (C) 2018 MediaTek Inc.
6 * Author: Ryder Lee <ryder.lee@mediatek.com>
7 */
8
9 #include <common.h>
10 #include <dm.h>
11 #include <hang.h>
12 #include <wdt.h>
13 #include <asm/io.h>
14 #include <linux/bitops.h>
15
16 #define MTK_WDT_MODE 0x00
17 #define MTK_WDT_LENGTH 0x04
18 #define MTK_WDT_RESTART 0x08
19 #define MTK_WDT_STATUS 0x0c
20 #define MTK_WDT_INTERVAL 0x10
21 #define MTK_WDT_SWRST 0x14
22 #define MTK_WDT_REQ_MODE 0x30
23 #define MTK_WDT_DEBUG_CTL 0x40
24
25 #define WDT_MODE_KEY (0x22 << 24)
26 #define WDT_MODE_EN BIT(0)
27 #define WDT_MODE_EXTPOL BIT(1)
28 #define WDT_MODE_EXTEN BIT(2)
29 #define WDT_MODE_IRQ_EN BIT(3)
30 #define WDT_MODE_DUAL_EN BIT(6)
31
32 #define WDT_LENGTH_KEY 0x8
33 #define WDT_LENGTH_TIMEOUT(n) ((n) << 5)
34
35 #define WDT_RESTART_KEY 0x1971
36 #define WDT_SWRST_KEY 0x1209
37
38 struct mtk_wdt_priv {
39 void __iomem *base;
40 };
41
mtk_wdt_reset(struct udevice * dev)42 static int mtk_wdt_reset(struct udevice *dev)
43 {
44 struct mtk_wdt_priv *priv = dev_get_priv(dev);
45
46 /* Reload watchdog duration */
47 writel(WDT_RESTART_KEY, priv->base + MTK_WDT_RESTART);
48
49 return 0;
50 }
51
mtk_wdt_stop(struct udevice * dev)52 static int mtk_wdt_stop(struct udevice *dev)
53 {
54 struct mtk_wdt_priv *priv = dev_get_priv(dev);
55
56 clrsetbits_le32(priv->base + MTK_WDT_MODE, WDT_MODE_EN, WDT_MODE_KEY);
57
58 return 0;
59 }
60
mtk_wdt_expire_now(struct udevice * dev,ulong flags)61 static int mtk_wdt_expire_now(struct udevice *dev, ulong flags)
62 {
63 struct mtk_wdt_priv *priv = dev_get_priv(dev);
64
65 /* Kick watchdog to prevent counter == 0 */
66 writel(WDT_RESTART_KEY, priv->base + MTK_WDT_RESTART);
67
68 /* Reset */
69 writel(WDT_SWRST_KEY, priv->base + MTK_WDT_SWRST);
70 hang();
71
72 return 0;
73 }
74
mtk_wdt_set_timeout(struct udevice * dev,u64 timeout_ms)75 static void mtk_wdt_set_timeout(struct udevice *dev, u64 timeout_ms)
76 {
77 struct mtk_wdt_priv *priv = dev_get_priv(dev);
78 u64 timeout_us;
79 u32 timeout_cc;
80 u32 length;
81
82 /*
83 * One WDT_LENGTH count is 512 ticks of the wdt clock
84 * Clock runs at 32768 Hz
85 * e.g. 15.625 ms per count (nominal)
86 * We want the ceiling after dividing timeout_ms by 15.625 ms
87 * We add 15624 prior to the divide to implement the ceiling
88 * We prevent over-flow by clamping the timeout_ms value here
89 * as the maximum WDT_LENGTH counts is 1023 -> 15.984375 sec
90 * We also enforce a minimum of 1 count
91 * Many watchdog peripherals have a self-imposed count of 1
92 * that is added to the register counts.
93 * The MediaTek docs lack details to know if this is the case here.
94 * So we enforce a minimum of 1 to guarantee operation.
95 */
96 if (timeout_ms > 15984)
97 timeout_ms = 15984;
98
99 timeout_us = timeout_ms * 1000;
100 timeout_cc = (15624 + timeout_us) / 15625;
101 if (timeout_cc == 0)
102 timeout_cc = 1;
103
104 length = WDT_LENGTH_TIMEOUT(timeout_cc) | WDT_LENGTH_KEY;
105 writel(length, priv->base + MTK_WDT_LENGTH);
106 }
107
mtk_wdt_start(struct udevice * dev,u64 timeout_ms,ulong flags)108 static int mtk_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
109 {
110 struct mtk_wdt_priv *priv = dev_get_priv(dev);
111
112 mtk_wdt_set_timeout(dev, timeout_ms);
113
114 mtk_wdt_reset(dev);
115
116 /* Enable watchdog reset signal */
117 setbits_le32(priv->base + MTK_WDT_MODE,
118 WDT_MODE_EN | WDT_MODE_KEY | WDT_MODE_EXTEN);
119
120 return 0;
121 }
122
mtk_wdt_probe(struct udevice * dev)123 static int mtk_wdt_probe(struct udevice *dev)
124 {
125 struct mtk_wdt_priv *priv = dev_get_priv(dev);
126
127 priv->base = dev_read_addr_ptr(dev);
128 if (!priv->base)
129 return -ENOENT;
130
131 /* Clear status */
132 clrsetbits_le32(priv->base + MTK_WDT_MODE,
133 WDT_MODE_IRQ_EN | WDT_MODE_EXTPOL, WDT_MODE_KEY);
134
135 return mtk_wdt_stop(dev);
136 }
137
138 static const struct wdt_ops mtk_wdt_ops = {
139 .start = mtk_wdt_start,
140 .reset = mtk_wdt_reset,
141 .stop = mtk_wdt_stop,
142 .expire_now = mtk_wdt_expire_now,
143 };
144
145 static const struct udevice_id mtk_wdt_ids[] = {
146 { .compatible = "mediatek,wdt"},
147 { .compatible = "mediatek,mt6589-wdt"},
148 {}
149 };
150
151 U_BOOT_DRIVER(mtk_wdt) = {
152 .name = "mtk_wdt",
153 .id = UCLASS_WDT,
154 .of_match = mtk_wdt_ids,
155 .priv_auto = sizeof(struct mtk_wdt_priv),
156 .probe = mtk_wdt_probe,
157 .ops = &mtk_wdt_ops,
158 .flags = DM_FLAG_PRE_RELOC,
159 };
160