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1// SPDX-License-Identifier: GPL-2.0
2// Copyright (c) 2018 Nuvoton Technology corporation.
3// Copyright (c) 2018 IBM Corp.
4
5#include <linux/bitops.h>
6#include <linux/clk.h>
7#include <linux/delay.h>
8#include <linux/interrupt.h>
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/of_irq.h>
12#include <linux/platform_device.h>
13#include <linux/slab.h>
14#include <linux/watchdog.h>
15
16#define NPCM_WTCR 0x1C
17
18#define NPCM_WTCLK (BIT(10) | BIT(11)) /* Clock divider */
19#define NPCM_WTE BIT(7) /* Enable */
20#define NPCM_WTIE BIT(6) /* Enable irq */
21#define NPCM_WTIS (BIT(4) | BIT(5)) /* Interval selection */
22#define NPCM_WTIF BIT(3) /* Interrupt flag*/
23#define NPCM_WTRF BIT(2) /* Reset flag */
24#define NPCM_WTRE BIT(1) /* Reset enable */
25#define NPCM_WTR BIT(0) /* Reset counter */
26
27/*
28 * Watchdog timeouts
29 *
30 * 170 msec: WTCLK=01 WTIS=00 VAL= 0x400
31 * 670 msec: WTCLK=01 WTIS=01 VAL= 0x410
32 * 1360 msec: WTCLK=10 WTIS=00 VAL= 0x800
33 * 2700 msec: WTCLK=01 WTIS=10 VAL= 0x420
34 * 5360 msec: WTCLK=10 WTIS=01 VAL= 0x810
35 * 10700 msec: WTCLK=01 WTIS=11 VAL= 0x430
36 * 21600 msec: WTCLK=10 WTIS=10 VAL= 0x820
37 * 43000 msec: WTCLK=11 WTIS=00 VAL= 0xC00
38 * 85600 msec: WTCLK=10 WTIS=11 VAL= 0x830
39 * 172000 msec: WTCLK=11 WTIS=01 VAL= 0xC10
40 * 687000 msec: WTCLK=11 WTIS=10 VAL= 0xC20
41 * 2750000 msec: WTCLK=11 WTIS=11 VAL= 0xC30
42 */
43
44struct npcm_wdt {
45 struct watchdog_device wdd;
46 void __iomem *reg;
47 struct clk *clk;
48};
49
50static inline struct npcm_wdt *to_npcm_wdt(struct watchdog_device *wdd)
51{
52 return container_of(wdd, struct npcm_wdt, wdd);
53}
54
55static int npcm_wdt_ping(struct watchdog_device *wdd)
56{
57 struct npcm_wdt *wdt = to_npcm_wdt(wdd);
58 u32 val;
59
60 val = readl(wdt->reg);
61 writel(val | NPCM_WTR, wdt->reg);
62
63 return 0;
64}
65
66static int npcm_wdt_start(struct watchdog_device *wdd)
67{
68 struct npcm_wdt *wdt = to_npcm_wdt(wdd);
69 u32 val;
70
71 if (wdt->clk)
72 clk_prepare_enable(wdt->clk);
73
74 if (wdd->timeout < 2)
75 val = 0x800;
76 else if (wdd->timeout < 3)
77 val = 0x420;
78 else if (wdd->timeout < 6)
79 val = 0x810;
80 else if (wdd->timeout < 11)
81 val = 0x430;
82 else if (wdd->timeout < 22)
83 val = 0x820;
84 else if (wdd->timeout < 44)
85 val = 0xC00;
86 else if (wdd->timeout < 87)
87 val = 0x830;
88 else if (wdd->timeout < 173)
89 val = 0xC10;
90 else if (wdd->timeout < 688)
91 val = 0xC20;
92 else
93 val = 0xC30;
94
95 val |= NPCM_WTRE | NPCM_WTE | NPCM_WTR | NPCM_WTIE;
96
97 writel(val, wdt->reg);
98
99 return 0;
100}
101
102static int npcm_wdt_stop(struct watchdog_device *wdd)
103{
104 struct npcm_wdt *wdt = to_npcm_wdt(wdd);
105
106 writel(0, wdt->reg);
107
108 if (wdt->clk)
109 clk_disable_unprepare(wdt->clk);
110
111 return 0;
112}
113
114static int npcm_wdt_set_timeout(struct watchdog_device *wdd,
115 unsigned int timeout)
116{
117 if (timeout < 2)
118 wdd->timeout = 1;
119 else if (timeout < 3)
120 wdd->timeout = 2;
121 else if (timeout < 6)
122 wdd->timeout = 5;
123 else if (timeout < 11)
124 wdd->timeout = 10;
125 else if (timeout < 22)
126 wdd->timeout = 21;
127 else if (timeout < 44)
128 wdd->timeout = 43;
129 else if (timeout < 87)
130 wdd->timeout = 86;
131 else if (timeout < 173)
132 wdd->timeout = 172;
133 else if (timeout < 688)
134 wdd->timeout = 687;
135 else
136 wdd->timeout = 2750;
137
138 if (watchdog_active(wdd))
139 npcm_wdt_start(wdd);
140
141 return 0;
142}
143
144static irqreturn_t npcm_wdt_interrupt(int irq, void *data)
145{
146 struct npcm_wdt *wdt = data;
147
148 watchdog_notify_pretimeout(&wdt->wdd);
149
150 return IRQ_HANDLED;
151}
152
153static int npcm_wdt_restart(struct watchdog_device *wdd,
154 unsigned long action, void *data)
155{
156 struct npcm_wdt *wdt = to_npcm_wdt(wdd);
157
158 /* For reset, we start the WDT clock and leave it running. */
159 if (wdt->clk)
160 clk_prepare_enable(wdt->clk);
161
162 writel(NPCM_WTR | NPCM_WTRE | NPCM_WTE, wdt->reg);
163 udelay(1000);
164
165 return 0;
166}
167
168static bool npcm_is_running(struct watchdog_device *wdd)
169{
170 struct npcm_wdt *wdt = to_npcm_wdt(wdd);
171
172 return readl(wdt->reg) & NPCM_WTE;
173}
174
175static const struct watchdog_info npcm_wdt_info = {
176 .identity = KBUILD_MODNAME,
177 .options = WDIOF_SETTIMEOUT
178 | WDIOF_KEEPALIVEPING
179 | WDIOF_MAGICCLOSE,
180};
181
182static const struct watchdog_ops npcm_wdt_ops = {
183 .owner = THIS_MODULE,
184 .start = npcm_wdt_start,
185 .stop = npcm_wdt_stop,
186 .ping = npcm_wdt_ping,
187 .set_timeout = npcm_wdt_set_timeout,
188 .restart = npcm_wdt_restart,
189};
190
191static int npcm_wdt_probe(struct platform_device *pdev)
192{
193 struct device *dev = &pdev->dev;
194 struct npcm_wdt *wdt;
195 int irq;
196 int ret;
197
198 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
199 if (!wdt)
200 return -ENOMEM;
201
202 wdt->reg = devm_platform_ioremap_resource(pdev, 0);
203 if (IS_ERR(wdt->reg))
204 return PTR_ERR(wdt->reg);
205
206 wdt->clk = devm_clk_get_optional(&pdev->dev, NULL);
207 if (IS_ERR(wdt->clk))
208 return PTR_ERR(wdt->clk);
209
210 irq = platform_get_irq(pdev, 0);
211 if (irq < 0)
212 return irq;
213
214 wdt->wdd.info = &npcm_wdt_info;
215 wdt->wdd.ops = &npcm_wdt_ops;
216 wdt->wdd.min_timeout = 1;
217 wdt->wdd.max_timeout = 2750;
218 wdt->wdd.parent = dev;
219
220 wdt->wdd.timeout = 86;
221 watchdog_init_timeout(&wdt->wdd, 0, dev);
222
223 /* Ensure timeout is able to be represented by the hardware */
224 npcm_wdt_set_timeout(&wdt->wdd, wdt->wdd.timeout);
225
226 if (npcm_is_running(&wdt->wdd)) {
227 /* Restart with the default or device-tree specified timeout */
228 npcm_wdt_start(&wdt->wdd);
229 set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
230 }
231
232 ret = devm_request_irq(dev, irq, npcm_wdt_interrupt, 0, "watchdog",
233 wdt);
234 if (ret)
235 return ret;
236
237 ret = devm_watchdog_register_device(dev, &wdt->wdd);
238 if (ret)
239 return ret;
240
241 dev_info(dev, "NPCM watchdog driver enabled\n");
242
243 return 0;
244}
245
246#ifdef CONFIG_OF
247static const struct of_device_id npcm_wdt_match[] = {
248 {.compatible = "nuvoton,wpcm450-wdt"},
249 {.compatible = "nuvoton,npcm750-wdt"},
250 {},
251};
252MODULE_DEVICE_TABLE(of, npcm_wdt_match);
253#endif
254
255static struct platform_driver npcm_wdt_driver = {
256 .probe = npcm_wdt_probe,
257 .driver = {
258 .name = "npcm-wdt",
259 .of_match_table = of_match_ptr(npcm_wdt_match),
260 },
261};
262module_platform_driver(npcm_wdt_driver);
263
264MODULE_AUTHOR("Joel Stanley");
265MODULE_DESCRIPTION("Watchdog driver for NPCM");
266MODULE_LICENSE("GPL v2");