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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
55static 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 */
63struct rti_wdt_device {
64 void __iomem *base;
65 unsigned long freq;
66 struct watchdog_device wdd;
67};
68
69static 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
103static 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
115static 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
156static 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
176static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd)
177{
178 return rti_wdt_get_timeleft_ms(wdd) / 1000;
179}
180
181static const struct watchdog_info rti_wdt_info = {
182 .options = WDIOF_KEEPALIVEPING,
183 .identity = "K3 RTI Watchdog",
184};
185
186static 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
193static int rti_wdt_probe(struct platform_device *pdev)
194{
195 int ret = 0;
196 struct device *dev = &pdev->dev;
197 struct watchdog_device *wdd;
198 struct rti_wdt_device *wdt;
199 struct clk *clk;
200 u32 last_ping = 0;
201
202 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
203 if (!wdt)
204 return -ENOMEM;
205
206 clk = clk_get(dev, NULL);
207 if (IS_ERR(clk))
208 return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n");
209
210 wdt->freq = clk_get_rate(clk);
211
212 clk_put(clk);
213
214 if (!wdt->freq) {
215 dev_err(dev, "Failed to get fck rate.\n");
216 return -EINVAL;
217 }
218
219 /*
220 * If watchdog is running at 32k clock, it is not accurate.
221 * Adjust frequency down in this case so that we don't pet
222 * the watchdog too often.
223 */
224 if (wdt->freq < 32768)
225 wdt->freq = wdt->freq * 9 / 10;
226
227 pm_runtime_enable(dev);
228 ret = pm_runtime_resume_and_get(dev);
229 if (ret < 0) {
230 pm_runtime_disable(&pdev->dev);
231 return dev_err_probe(dev, ret, "runtime pm failed\n");
232 }
233
234 platform_set_drvdata(pdev, wdt);
235
236 wdd = &wdt->wdd;
237 wdd->info = &rti_wdt_info;
238 wdd->ops = &rti_wdt_ops;
239 wdd->min_timeout = 1;
240 wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) /
241 wdt->freq * 1000;
242 wdd->parent = dev;
243
244 watchdog_set_drvdata(wdd, wdt);
245 watchdog_set_nowayout(wdd, 1);
246 watchdog_set_restart_priority(wdd, 128);
247
248 wdt->base = devm_platform_ioremap_resource(pdev, 0);
249 if (IS_ERR(wdt->base)) {
250 ret = PTR_ERR(wdt->base);
251 goto err_iomap;
252 }
253
254 if (readl(wdt->base + RTIDWDCTRL) == WDENABLE_KEY) {
255 int preset_heartbeat;
256 u32 time_left_ms;
257 u64 heartbeat_ms;
258 u32 wsize;
259
260 set_bit(WDOG_HW_RUNNING, &wdd->status);
261 time_left_ms = rti_wdt_get_timeleft_ms(wdd);
262 heartbeat_ms = readl(wdt->base + RTIDWDPRLD);
263 heartbeat_ms <<= WDT_PRELOAD_SHIFT;
264 heartbeat_ms *= 1000;
265 do_div(heartbeat_ms, wdt->freq);
266 preset_heartbeat = heartbeat_ms + 500;
267 preset_heartbeat /= 1000;
268 if (preset_heartbeat != heartbeat)
269 dev_warn(dev, "watchdog already running, ignoring heartbeat config!\n");
270
271 heartbeat = preset_heartbeat;
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
300err_iomap:
301 pm_runtime_put_sync(&pdev->dev);
302 pm_runtime_disable(&pdev->dev);
303
304 return ret;
305}
306
307static 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
318static const struct of_device_id rti_wdt_of_match[] = {
319 { .compatible = "ti,j7-rti-wdt", },
320 {},
321};
322MODULE_DEVICE_TABLE(of, rti_wdt_of_match);
323
324static 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
333module_platform_driver(rti_wdt_driver);
334
335MODULE_AUTHOR("Tero Kristo <t-kristo@ti.com>");
336MODULE_DESCRIPTION("K3 RTI Watchdog Driver");
337
338module_param(heartbeat, int, 0);
339MODULE_PARM_DESC(heartbeat,
340 "Watchdog heartbeat period in seconds from 1 to "
341 __MODULE_STRING(MAX_HEARTBEAT) ", default "
342 __MODULE_STRING(DEFAULT_HEARTBEAT));
343
344MODULE_LICENSE("GPL");
345MODULE_ALIAS("platform:rti-wdt");