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gerrit.devboardsforandroid.linaro.org / platform / external / u-boot / 787fcf5c004d3e4e9fd4b8b6e092bcfe73714cbb / . / drivers / watchdog / mt7620_wdt.c
blob: fe89721ddb90997c8c5f100dbf24b6b2d408de84 [file] [log] [blame]
Weijie Gaobba4ec82020-11-12 16:36:28 +0800[diff] [blame]1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2020 MediaTek Inc.
4 *
5 * Author: Weijie Gao <weijie.gao@mediatek.com>
6 *
7 * Watchdog timer for MT7620 and earlier SoCs
8 */
9
10#include <div64.h>
11#include <dm.h>
12#include <reset.h>
13#include <wdt.h>
14#include <linux/bitops.h>
15#include <linux/io.h>
16
17struct mt7620_wdt {
18 void __iomem *regs;
19 u64 timeout;
20};
21
22#define TIMER_FREQ 40000000
23#define TIMER_MASK 0xffff
24#define TIMER_PRESCALE 65536
25
26#define TIMER_LOAD 0x00
27#define TIMER_CTL 0x08
28
29#define TIMER_ENABLE BIT(7)
30#define TIMER_MODE_SHIFT 4
31#define TIMER_MODE_WDT 3
32#define TIMER_PRESCALE_SHIFT 0
33#define TIMER_PRESCALE_65536 15
34
35static void mt7620_wdt_ping(struct mt7620_wdt *priv)
36{
37 u64 val;
38
39 val = (TIMER_FREQ / TIMER_PRESCALE) * priv->timeout;
40 do_div(val, 1000);
41
42 if (val > TIMER_MASK)
43 val = TIMER_MASK;
44
45 writel(val, priv->regs + TIMER_LOAD);
46}
47
48static int mt7620_wdt_start(struct udevice *dev, u64 ms, ulong flags)
49{
50 struct mt7620_wdt *priv = dev_get_priv(dev);
51
52 priv->timeout = ms;
53 mt7620_wdt_ping(priv);
54
55 writel(TIMER_ENABLE | (TIMER_MODE_WDT << TIMER_MODE_SHIFT) |
56 (TIMER_PRESCALE_65536 << TIMER_PRESCALE_SHIFT),
57 priv->regs + TIMER_CTL);
58
59 return 0;
60}
61
62static int mt7620_wdt_stop(struct udevice *dev)
63{
64 struct mt7620_wdt *priv = dev_get_priv(dev);
65
66 mt7620_wdt_ping(priv);
67
68 clrbits_32(priv->regs + TIMER_CTL, TIMER_ENABLE);
69
70 return 0;
71}
72
73static int mt7620_wdt_reset(struct udevice *dev)
74{
75 struct mt7620_wdt *priv = dev_get_priv(dev);
76
77 mt7620_wdt_ping(priv);
78
79 return 0;
80}
81
82static int mt7620_wdt_expire_now(struct udevice *dev, ulong flags)
83{
84 struct mt7620_wdt *priv = dev_get_priv(dev);
85
86 mt7620_wdt_start(dev, 1, flags);
87
88 /*
89 * 0 will disable the timer directly, a positive number must be used
90 * instead. Since the timer is a countdown timer, 1 (tick) is used.
91 *
92 * For a timer with input clock = 40MHz, 1 timer tick is short
93 * enough to trigger a timeout immediately.
94 *
95 * Restore prescale to 1, and load timer with 1 to trigger timeout.
96 */
97 writel(TIMER_ENABLE | (TIMER_MODE_WDT << TIMER_MODE_SHIFT),
98 priv->regs + TIMER_CTL);
99 writel(1, priv->regs + TIMER_LOAD);
100
101 return 0;
102}
103
104static int mt7620_wdt_probe(struct udevice *dev)
105{
106 struct mt7620_wdt *priv = dev_get_priv(dev);
107 struct reset_ctl reset_wdt;
108 int ret;
109
110 ret = reset_get_by_index(dev, 0, &reset_wdt);
111 if (!ret)
112 reset_deassert(&reset_wdt);
113
114 priv->regs = dev_remap_addr(dev);
115 if (!priv->regs)
116 return -EINVAL;
117
118 mt7620_wdt_stop(dev);
119
120 return 0;
121}
122
123static const struct wdt_ops mt7620_wdt_ops = {
124 .start = mt7620_wdt_start,
125 .reset = mt7620_wdt_reset,
126 .stop = mt7620_wdt_stop,
127 .expire_now = mt7620_wdt_expire_now,
128};
129
130static const struct udevice_id mt7620_wdt_ids[] = {
131 { .compatible = "mediatek,mt7620-wdt" },
132 {}
133};
134
135U_BOOT_DRIVER(mt7620_wdt) = {
136 .name = "mt7620_wdt",
137 .id = UCLASS_WDT,
138 .of_match = mt7620_wdt_ids,
139 .probe = mt7620_wdt_probe,
140 .priv_auto = sizeof(struct mt7620_wdt),
141 .ops = &mt7620_wdt_ops,
142};