1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Watchdog driver for the K3 RTI module
4 *
5 * (c) Copyright 2019-2020 Texas Instruments Inc.
6 * All rights reserved.
7 */
8
9 #include <linux/clk.h>
10 #include <linux/device.h>
11 #include <linux/err.h>
12 #include <linux/io.h>
13 #include <linux/kernel.h>
14 #include <linux/mod_devicetable.h>
15 #include <linux/module.h>
16 #include <linux/moduleparam.h>
17 #include <linux/platform_device.h>
18 #include <linux/pm_runtime.h>
19 #include <linux/types.h>
20 #include <linux/watchdog.h>
21
22 #define DEFAULT_HEARTBEAT 60
23
24 /* Max heartbeat is calculated at 32kHz source clock */
25 #define MAX_HEARTBEAT 1000
26
27 /* Timer register set definition */
28 #define RTIDWDCTRL 0x90
29 #define RTIDWDPRLD 0x94
30 #define RTIWDSTATUS 0x98
31 #define RTIWDKEY 0x9c
32 #define RTIDWDCNTR 0xa0
33 #define RTIWWDRXCTRL 0xa4
34 #define RTIWWDSIZECTRL 0xa8
35
36 #define RTIWWDRX_NMI 0xa
37
38 #define RTIWWDSIZE_50P 0x50
39 #define RTIWWDSIZE_25P 0x500
40 #define RTIWWDSIZE_12P5 0x5000
41 #define RTIWWDSIZE_6P25 0x50000
42 #define RTIWWDSIZE_3P125 0x500000
43
44 #define WDENABLE_KEY 0xa98559da
45
46 #define WDKEY_SEQ0 0xe51a
47 #define WDKEY_SEQ1 0xa35c
48
49 #define WDT_PRELOAD_SHIFT 13
50
51 #define WDT_PRELOAD_MAX 0xfff
52
53 #define DWDST BIT(1)
54
55 static int heartbeat = DEFAULT_HEARTBEAT;
56
57 /*
58 * struct to hold data for each WDT device
59 * @base - base io address of WD device
60 * @freq - source clock frequency of WDT
61 * @wdd - hold watchdog device as is in WDT core
62 */
63 struct rti_wdt_device {
64 void __iomem *base;
65 unsigned long freq;
66 struct watchdog_device wdd;
67 };
68
rti_wdt_start(struct watchdog_device * wdd)69 static int rti_wdt_start(struct watchdog_device *wdd)
70 {
71 u32 timer_margin;
72 struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
73
74 /* set timeout period */
75 timer_margin = (u64)wdd->timeout * wdt->freq;
76 timer_margin >>= WDT_PRELOAD_SHIFT;
77 if (timer_margin > WDT_PRELOAD_MAX)
78 timer_margin = WDT_PRELOAD_MAX;
79 writel_relaxed(timer_margin, wdt->base + RTIDWDPRLD);
80
81 /*
82 * RTI only supports a windowed mode, where the watchdog can only
83 * be petted during the open window; not too early or not too late.
84 * The HW configuration options only allow for the open window size
85 * to be 50% or less than that; we obviouly want to configure the open
86 * window as large as possible so we select the 50% option.
87 */
88 wdd->min_hw_heartbeat_ms = 500 * wdd->timeout;
89
90 /* Generate NMI when wdt expires */
91 writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL);
92
93 /* Open window size 50%; this is the largest window size available */
94 writel_relaxed(RTIWWDSIZE_50P, wdt->base + RTIWWDSIZECTRL);
95
96 readl_relaxed(wdt->base + RTIWWDSIZECTRL);
97
98 /* enable watchdog */
99 writel_relaxed(WDENABLE_KEY, wdt->base + RTIDWDCTRL);
100 return 0;
101 }
102
rti_wdt_ping(struct watchdog_device * wdd)103 static int rti_wdt_ping(struct watchdog_device *wdd)
104 {
105 struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
106
107 /* put watchdog in service state */
108 writel_relaxed(WDKEY_SEQ0, wdt->base + RTIWDKEY);
109 /* put watchdog in active state */
110 writel_relaxed(WDKEY_SEQ1, wdt->base + RTIWDKEY);
111
112 return 0;
113 }
114
rti_wdt_setup_hw_hb(struct watchdog_device * wdd,u32 wsize)115 static int rti_wdt_setup_hw_hb(struct watchdog_device *wdd, u32 wsize)
116 {
117 /*
118 * RTI only supports a windowed mode, where the watchdog can only
119 * be petted during the open window; not too early or not too late.
120 * The HW configuration options only allow for the open window size
121 * to be 50% or less than that.
122 */
123 switch (wsize) {
124 case RTIWWDSIZE_50P:
125 /* 50% open window => 50% min heartbeat */
126 wdd->min_hw_heartbeat_ms = 500 * heartbeat;
127 break;
128
129 case RTIWWDSIZE_25P:
130 /* 25% open window => 75% min heartbeat */
131 wdd->min_hw_heartbeat_ms = 750 * heartbeat;
132 break;
133
134 case RTIWWDSIZE_12P5:
135 /* 12.5% open window => 87.5% min heartbeat */
136 wdd->min_hw_heartbeat_ms = 875 * heartbeat;
137 break;
138
139 case RTIWWDSIZE_6P25:
140 /* 6.5% open window => 93.5% min heartbeat */
141 wdd->min_hw_heartbeat_ms = 935 * heartbeat;
142 break;
143
144 case RTIWWDSIZE_3P125:
145 /* 3.125% open window => 96.9% min heartbeat */
146 wdd->min_hw_heartbeat_ms = 969 * heartbeat;
147 break;
148
149 default:
150 return -EINVAL;
151 }
152
153 return 0;
154 }
155
rti_wdt_get_timeleft_ms(struct watchdog_device * wdd)156 static unsigned int rti_wdt_get_timeleft_ms(struct watchdog_device *wdd)
157 {
158 u64 timer_counter;
159 u32 val;
160 struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
161
162 /* if timeout has occurred then return 0 */
163 val = readl_relaxed(wdt->base + RTIWDSTATUS);
164 if (val & DWDST)
165 return 0;
166
167 timer_counter = readl_relaxed(wdt->base + RTIDWDCNTR);
168
169 timer_counter *= 1000;
170
171 do_div(timer_counter, wdt->freq);
172
173 return timer_counter;
174 }
175
rti_wdt_get_timeleft(struct watchdog_device * wdd)176 static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd)
177 {
178 return rti_wdt_get_timeleft_ms(wdd) / 1000;
179 }
180
181 static const struct watchdog_info rti_wdt_info = {
182 .options = WDIOF_KEEPALIVEPING,
183 .identity = "K3 RTI Watchdog",
184 };
185
186 static const struct watchdog_ops rti_wdt_ops = {
187 .owner = THIS_MODULE,
188 .start = rti_wdt_start,
189 .ping = rti_wdt_ping,
190 .get_timeleft = rti_wdt_get_timeleft,
191 };
192
rti_wdt_probe(struct platform_device * pdev)193 static int rti_wdt_probe(struct platform_device *pdev)
194 {
195 int ret = 0;
196 struct device *dev = &pdev->dev;
197 struct resource *wdt_mem;
198 struct watchdog_device *wdd;
199 struct rti_wdt_device *wdt;
200 struct clk *clk;
201 u32 last_ping = 0;
202
203 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
204 if (!wdt)
205 return -ENOMEM;
206
207 clk = clk_get(dev, NULL);
208 if (IS_ERR(clk))
209 return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n");
210
211 wdt->freq = clk_get_rate(clk);
212
213 clk_put(clk);
214
215 if (!wdt->freq) {
216 dev_err(dev, "Failed to get fck rate.\n");
217 return -EINVAL;
218 }
219
220 /*
221 * If watchdog is running at 32k clock, it is not accurate.
222 * Adjust frequency down in this case so that we don't pet
223 * the watchdog too often.
224 */
225 if (wdt->freq < 32768)
226 wdt->freq = wdt->freq * 9 / 10;
227
228 pm_runtime_enable(dev);
229 ret = pm_runtime_get_sync(dev);
230 if (ret) {
231 pm_runtime_put_noidle(dev);
232 return dev_err_probe(dev, ret, "runtime pm failed\n");
233 }
234
235 platform_set_drvdata(pdev, wdt);
236
237 wdd = &wdt->wdd;
238 wdd->info = &rti_wdt_info;
239 wdd->ops = &rti_wdt_ops;
240 wdd->min_timeout = 1;
241 wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) /
242 wdt->freq * 1000;
243 wdd->parent = dev;
244
245 watchdog_set_drvdata(wdd, wdt);
246 watchdog_set_nowayout(wdd, 1);
247 watchdog_set_restart_priority(wdd, 128);
248
249 wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
250 wdt->base = devm_ioremap_resource(dev, wdt_mem);
251 if (IS_ERR(wdt->base)) {
252 ret = PTR_ERR(wdt->base);
253 goto err_iomap;
254 }
255
256 if (readl(wdt->base + RTIDWDCTRL) == WDENABLE_KEY) {
257 u32 time_left_ms;
258 u64 heartbeat_ms;
259 u32 wsize;
260
261 set_bit(WDOG_HW_RUNNING, &wdd->status);
262 time_left_ms = rti_wdt_get_timeleft_ms(wdd);
263 heartbeat_ms = readl(wdt->base + RTIDWDPRLD);
264 heartbeat_ms <<= WDT_PRELOAD_SHIFT;
265 heartbeat_ms *= 1000;
266 do_div(heartbeat_ms, wdt->freq);
267 if (heartbeat_ms != heartbeat * 1000)
268 dev_warn(dev, "watchdog already running, ignoring heartbeat config!\n");
269
270 heartbeat = heartbeat_ms;
271 heartbeat /= 1000;
272
273 wsize = readl(wdt->base + RTIWWDSIZECTRL);
274 ret = rti_wdt_setup_hw_hb(wdd, wsize);
275 if (ret) {
276 dev_err(dev, "bad window size.\n");
277 goto err_iomap;
278 }
279
280 last_ping = heartbeat_ms - time_left_ms;
281 if (time_left_ms > heartbeat_ms) {
282 dev_warn(dev, "time_left > heartbeat? Assuming last ping just before now.\n");
283 last_ping = 0;
284 }
285 }
286
287 watchdog_init_timeout(wdd, heartbeat, dev);
288
289 ret = watchdog_register_device(wdd);
290 if (ret) {
291 dev_err(dev, "cannot register watchdog device\n");
292 goto err_iomap;
293 }
294
295 if (last_ping)
296 watchdog_set_last_hw_keepalive(wdd, last_ping);
297
298 return 0;
299
300 err_iomap:
301 pm_runtime_put_sync(&pdev->dev);
302 pm_runtime_disable(&pdev->dev);
303
304 return ret;
305 }
306
rti_wdt_remove(struct platform_device * pdev)307 static int rti_wdt_remove(struct platform_device *pdev)
308 {
309 struct rti_wdt_device *wdt = platform_get_drvdata(pdev);
310
311 watchdog_unregister_device(&wdt->wdd);
312 pm_runtime_put(&pdev->dev);
313 pm_runtime_disable(&pdev->dev);
314
315 return 0;
316 }
317
318 static const struct of_device_id rti_wdt_of_match[] = {
319 { .compatible = "ti,j7-rti-wdt", },
320 {},
321 };
322 MODULE_DEVICE_TABLE(of, rti_wdt_of_match);
323
324 static struct platform_driver rti_wdt_driver = {
325 .driver = {
326 .name = "rti-wdt",
327 .of_match_table = rti_wdt_of_match,
328 },
329 .probe = rti_wdt_probe,
330 .remove = rti_wdt_remove,
331 };
332
333 module_platform_driver(rti_wdt_driver);
334
335 MODULE_AUTHOR("Tero Kristo <t-kristo@ti.com>");
336 MODULE_DESCRIPTION("K3 RTI Watchdog Driver");
337
338 module_param(heartbeat, int, 0);
339 MODULE_PARM_DESC(heartbeat,
340 "Watchdog heartbeat period in seconds from 1 to "
341 __MODULE_STRING(MAX_HEARTBEAT) ", default "
342 __MODULE_STRING(DEFAULT_HEARTBEAT));
343
344 MODULE_LICENSE("GPL");
345 MODULE_ALIAS("platform:rti-wdt");
346