1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * drivers/char/watchdog/davinci_wdt.c
4  *
5  * Watchdog driver for DaVinci DM644x/DM646x processors
6  *
7  * Copyright (C) 2006-2013 Texas Instruments.
8  *
9  * 2007 (c) MontaVista Software, Inc.
10  */
11 
12 #include <linux/module.h>
13 #include <linux/moduleparam.h>
14 #include <linux/mod_devicetable.h>
15 #include <linux/types.h>
16 #include <linux/kernel.h>
17 #include <linux/watchdog.h>
18 #include <linux/platform_device.h>
19 #include <linux/io.h>
20 #include <linux/device.h>
21 #include <linux/clk.h>
22 #include <linux/err.h>
23 
24 #define MODULE_NAME "DAVINCI-WDT: "
25 
26 #define DEFAULT_HEARTBEAT 60
27 #define MAX_HEARTBEAT     600	/* really the max margin is 264/27MHz*/
28 
29 /* Timer register set definition */
30 #define PID12	(0x0)
31 #define EMUMGT	(0x4)
32 #define TIM12	(0x10)
33 #define TIM34	(0x14)
34 #define PRD12	(0x18)
35 #define PRD34	(0x1C)
36 #define TCR	(0x20)
37 #define TGCR	(0x24)
38 #define WDTCR	(0x28)
39 
40 /* TCR bit definitions */
41 #define ENAMODE12_DISABLED	(0 << 6)
42 #define ENAMODE12_ONESHOT	(1 << 6)
43 #define ENAMODE12_PERIODIC	(2 << 6)
44 
45 /* TGCR bit definitions */
46 #define TIM12RS_UNRESET		(1 << 0)
47 #define TIM34RS_UNRESET		(1 << 1)
48 #define TIMMODE_64BIT_WDOG      (2 << 2)
49 
50 /* WDTCR bit definitions */
51 #define WDEN			(1 << 14)
52 #define WDFLAG			(1 << 15)
53 #define WDKEY_SEQ0		(0xa5c6 << 16)
54 #define WDKEY_SEQ1		(0xda7e << 16)
55 
56 static int heartbeat;
57 
58 /*
59  * struct to hold data for each WDT device
60  * @base - base io address of WD device
61  * @clk - source clock of WDT
62  * @wdd - hold watchdog device as is in WDT core
63  */
64 struct davinci_wdt_device {
65 	void __iomem		*base;
66 	struct clk		*clk;
67 	struct watchdog_device	wdd;
68 };
69 
70 static int davinci_wdt_start(struct watchdog_device *wdd)
71 {
72 	u32 tgcr;
73 	u32 timer_margin;
74 	unsigned long wdt_freq;
75 	struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
76 
77 	wdt_freq = clk_get_rate(davinci_wdt->clk);
78 
79 	/* disable, internal clock source */
80 	iowrite32(0, davinci_wdt->base + TCR);
81 	/* reset timer, set mode to 64-bit watchdog, and unreset */
82 	iowrite32(0, davinci_wdt->base + TGCR);
83 	tgcr = TIMMODE_64BIT_WDOG | TIM12RS_UNRESET | TIM34RS_UNRESET;
84 	iowrite32(tgcr, davinci_wdt->base + TGCR);
85 	/* clear counter regs */
86 	iowrite32(0, davinci_wdt->base + TIM12);
87 	iowrite32(0, davinci_wdt->base + TIM34);
88 	/* set timeout period */
89 	timer_margin = (((u64)wdd->timeout * wdt_freq) & 0xffffffff);
90 	iowrite32(timer_margin, davinci_wdt->base + PRD12);
91 	timer_margin = (((u64)wdd->timeout * wdt_freq) >> 32);
92 	iowrite32(timer_margin, davinci_wdt->base + PRD34);
93 	/* enable run continuously */
94 	iowrite32(ENAMODE12_PERIODIC, davinci_wdt->base + TCR);
95 	/* Once the WDT is in pre-active state write to
96 	 * TIM12, TIM34, PRD12, PRD34, TCR, TGCR, WDTCR are
97 	 * write protected (except for the WDKEY field)
98 	 */
99 	/* put watchdog in pre-active state */
100 	iowrite32(WDKEY_SEQ0 | WDEN, davinci_wdt->base + WDTCR);
101 	/* put watchdog in active state */
102 	iowrite32(WDKEY_SEQ1 | WDEN, davinci_wdt->base + WDTCR);
103 	return 0;
104 }
105 
106 static int davinci_wdt_ping(struct watchdog_device *wdd)
107 {
108 	struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
109 
110 	/* put watchdog in service state */
111 	iowrite32(WDKEY_SEQ0, davinci_wdt->base + WDTCR);
112 	/* put watchdog in active state */
113 	iowrite32(WDKEY_SEQ1, davinci_wdt->base + WDTCR);
114 	return 0;
115 }
116 
117 static unsigned int davinci_wdt_get_timeleft(struct watchdog_device *wdd)
118 {
119 	u64 timer_counter;
120 	unsigned long freq;
121 	u32 val;
122 	struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
123 
124 	/* if timeout has occured then return 0 */
125 	val = ioread32(davinci_wdt->base + WDTCR);
126 	if (val & WDFLAG)
127 		return 0;
128 
129 	freq = clk_get_rate(davinci_wdt->clk);
130 
131 	if (!freq)
132 		return 0;
133 
134 	timer_counter = ioread32(davinci_wdt->base + TIM12);
135 	timer_counter |= ((u64)ioread32(davinci_wdt->base + TIM34) << 32);
136 
137 	do_div(timer_counter, freq);
138 
139 	return wdd->timeout - timer_counter;
140 }
141 
142 static int davinci_wdt_restart(struct watchdog_device *wdd,
143 			       unsigned long action, void *data)
144 {
145 	struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
146 	u32 tgcr, wdtcr;
147 
148 	/* disable, internal clock source */
149 	iowrite32(0, davinci_wdt->base + TCR);
150 
151 	/* reset timer, set mode to 64-bit watchdog, and unreset */
152 	tgcr = 0;
153 	iowrite32(tgcr, davinci_wdt->base + TGCR);
154 	tgcr = TIMMODE_64BIT_WDOG | TIM12RS_UNRESET | TIM34RS_UNRESET;
155 	iowrite32(tgcr, davinci_wdt->base + TGCR);
156 
157 	/* clear counter and period regs */
158 	iowrite32(0, davinci_wdt->base + TIM12);
159 	iowrite32(0, davinci_wdt->base + TIM34);
160 	iowrite32(0, davinci_wdt->base + PRD12);
161 	iowrite32(0, davinci_wdt->base + PRD34);
162 
163 	/* put watchdog in pre-active state */
164 	wdtcr = WDKEY_SEQ0 | WDEN;
165 	iowrite32(wdtcr, davinci_wdt->base + WDTCR);
166 
167 	/* put watchdog in active state */
168 	wdtcr = WDKEY_SEQ1 | WDEN;
169 	iowrite32(wdtcr, davinci_wdt->base + WDTCR);
170 
171 	/* write an invalid value to the WDKEY field to trigger a restart */
172 	wdtcr = 0x00004000;
173 	iowrite32(wdtcr, davinci_wdt->base + WDTCR);
174 
175 	return 0;
176 }
177 
178 static const struct watchdog_info davinci_wdt_info = {
179 	.options = WDIOF_KEEPALIVEPING,
180 	.identity = "DaVinci/Keystone Watchdog",
181 };
182 
183 static const struct watchdog_ops davinci_wdt_ops = {
184 	.owner		= THIS_MODULE,
185 	.start		= davinci_wdt_start,
186 	.stop		= davinci_wdt_ping,
187 	.ping		= davinci_wdt_ping,
188 	.get_timeleft	= davinci_wdt_get_timeleft,
189 	.restart	= davinci_wdt_restart,
190 };
191 
192 static void davinci_clk_disable_unprepare(void *data)
193 {
194 	clk_disable_unprepare(data);
195 }
196 
197 static int davinci_wdt_probe(struct platform_device *pdev)
198 {
199 	int ret = 0;
200 	struct device *dev = &pdev->dev;
201 	struct watchdog_device *wdd;
202 	struct davinci_wdt_device *davinci_wdt;
203 
204 	davinci_wdt = devm_kzalloc(dev, sizeof(*davinci_wdt), GFP_KERNEL);
205 	if (!davinci_wdt)
206 		return -ENOMEM;
207 
208 	davinci_wdt->clk = devm_clk_get(dev, NULL);
209 
210 	if (IS_ERR(davinci_wdt->clk)) {
211 		if (PTR_ERR(davinci_wdt->clk) != -EPROBE_DEFER)
212 			dev_err(dev, "failed to get clock node\n");
213 		return PTR_ERR(davinci_wdt->clk);
214 	}
215 
216 	ret = clk_prepare_enable(davinci_wdt->clk);
217 	if (ret) {
218 		dev_err(dev, "failed to prepare clock\n");
219 		return ret;
220 	}
221 	ret = devm_add_action_or_reset(dev, davinci_clk_disable_unprepare,
222 				       davinci_wdt->clk);
223 	if (ret)
224 		return ret;
225 
226 	platform_set_drvdata(pdev, davinci_wdt);
227 
228 	wdd			= &davinci_wdt->wdd;
229 	wdd->info		= &davinci_wdt_info;
230 	wdd->ops		= &davinci_wdt_ops;
231 	wdd->min_timeout	= 1;
232 	wdd->max_timeout	= MAX_HEARTBEAT;
233 	wdd->timeout		= DEFAULT_HEARTBEAT;
234 	wdd->parent		= dev;
235 
236 	watchdog_init_timeout(wdd, heartbeat, dev);
237 
238 	dev_info(dev, "heartbeat %d sec\n", wdd->timeout);
239 
240 	watchdog_set_drvdata(wdd, davinci_wdt);
241 	watchdog_set_nowayout(wdd, 1);
242 	watchdog_set_restart_priority(wdd, 128);
243 
244 	davinci_wdt->base = devm_platform_ioremap_resource(pdev, 0);
245 	if (IS_ERR(davinci_wdt->base))
246 		return PTR_ERR(davinci_wdt->base);
247 
248 	return devm_watchdog_register_device(dev, wdd);
249 }
250 
251 static const struct of_device_id davinci_wdt_of_match[] = {
252 	{ .compatible = "ti,davinci-wdt", },
253 	{},
254 };
255 MODULE_DEVICE_TABLE(of, davinci_wdt_of_match);
256 
257 static struct platform_driver platform_wdt_driver = {
258 	.driver = {
259 		.name = "davinci-wdt",
260 		.of_match_table = davinci_wdt_of_match,
261 	},
262 	.probe = davinci_wdt_probe,
263 };
264 
265 module_platform_driver(platform_wdt_driver);
266 
267 MODULE_AUTHOR("Texas Instruments");
268 MODULE_DESCRIPTION("DaVinci Watchdog Driver");
269 
270 module_param(heartbeat, int, 0);
271 MODULE_PARM_DESC(heartbeat,
272 		 "Watchdog heartbeat period in seconds from 1 to "
273 		 __MODULE_STRING(MAX_HEARTBEAT) ", default "
274 		 __MODULE_STRING(DEFAULT_HEARTBEAT));
275 
276 MODULE_LICENSE("GPL");
277 MODULE_ALIAS("platform:davinci-wdt");
278