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
davinci_wdt_start(struct watchdog_device * wdd)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
davinci_wdt_ping(struct watchdog_device * wdd)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
davinci_wdt_get_timeleft(struct watchdog_device * wdd)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
davinci_wdt_restart(struct watchdog_device * wdd,unsigned long action,void * data)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
davinci_clk_disable_unprepare(void * data)192 static void davinci_clk_disable_unprepare(void *data)
193 {
194 clk_disable_unprepare(data);
195 }
196
davinci_wdt_probe(struct platform_device * pdev)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 if (IS_ERR(davinci_wdt->clk))
210 return dev_err_probe(dev, PTR_ERR(davinci_wdt->clk),
211 "failed to get clock node\n");
212
213 ret = clk_prepare_enable(davinci_wdt->clk);
214 if (ret) {
215 dev_err(dev, "failed to prepare clock\n");
216 return ret;
217 }
218 ret = devm_add_action_or_reset(dev, davinci_clk_disable_unprepare,
219 davinci_wdt->clk);
220 if (ret)
221 return ret;
222
223 platform_set_drvdata(pdev, davinci_wdt);
224
225 wdd = &davinci_wdt->wdd;
226 wdd->info = &davinci_wdt_info;
227 wdd->ops = &davinci_wdt_ops;
228 wdd->min_timeout = 1;
229 wdd->max_timeout = MAX_HEARTBEAT;
230 wdd->timeout = DEFAULT_HEARTBEAT;
231 wdd->parent = dev;
232
233 watchdog_init_timeout(wdd, heartbeat, dev);
234
235 dev_info(dev, "heartbeat %d sec\n", wdd->timeout);
236
237 watchdog_set_drvdata(wdd, davinci_wdt);
238 watchdog_set_nowayout(wdd, 1);
239 watchdog_set_restart_priority(wdd, 128);
240
241 davinci_wdt->base = devm_platform_ioremap_resource(pdev, 0);
242 if (IS_ERR(davinci_wdt->base))
243 return PTR_ERR(davinci_wdt->base);
244
245 return devm_watchdog_register_device(dev, wdd);
246 }
247
248 static const struct of_device_id davinci_wdt_of_match[] = {
249 { .compatible = "ti,davinci-wdt", },
250 {},
251 };
252 MODULE_DEVICE_TABLE(of, davinci_wdt_of_match);
253
254 static struct platform_driver platform_wdt_driver = {
255 .driver = {
256 .name = "davinci-wdt",
257 .of_match_table = davinci_wdt_of_match,
258 },
259 .probe = davinci_wdt_probe,
260 };
261
262 module_platform_driver(platform_wdt_driver);
263
264 MODULE_AUTHOR("Texas Instruments");
265 MODULE_DESCRIPTION("DaVinci Watchdog Driver");
266
267 module_param(heartbeat, int, 0);
268 MODULE_PARM_DESC(heartbeat,
269 "Watchdog heartbeat period in seconds from 1 to "
270 __MODULE_STRING(MAX_HEARTBEAT) ", default "
271 __MODULE_STRING(DEFAULT_HEARTBEAT));
272
273 MODULE_LICENSE("GPL");
274 MODULE_ALIAS("platform:davinci-wdt");
275