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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Imagination Technologies PowerDown Controller Watchdog Timer.
4 *
5 * Copyright (c) 2014 Imagination Technologies Ltd.
6 *
7 * Based on drivers/watchdog/sunxi_wdt.c Copyright (c) 2013 Carlo Caione
8 * 2012 Henrik Nordstrom
9 *
10 * Notes
11 * -----
12 * The timeout value is rounded to the next power of two clock cycles.
13 * This is configured using the PDC_WDT_CONFIG register, according to this
14 * formula:
15 *
16 * timeout = 2^(delay + 1) clock cycles
17 *
18 * Where 'delay' is the value written in PDC_WDT_CONFIG register.
19 *
20 * Therefore, the hardware only allows to program watchdog timeouts, expressed
21 * as a power of two number of watchdog clock cycles. The current implementation
22 * guarantees that the actual watchdog timeout will be _at least_ the value
23 * programmed in the imgpdg_wdt driver.
24 *
25 * The following table shows how the user-configured timeout relates
26 * to the actual hardware timeout (watchdog clock @ 40000 Hz):
27 *
28 * input timeout | WD_DELAY | actual timeout
29 * -----------------------------------
30 * 10 | 18 | 13 seconds
31 * 20 | 19 | 26 seconds
32 * 30 | 20 | 52 seconds
33 * 60 | 21 | 104 seconds
34 *
35 * Albeit coarse, this granularity would suffice most watchdog uses.
36 * If the platform allows it, the user should be able to change the watchdog
37 * clock rate and achieve a finer timeout granularity.
38 */
39
40#include <linux/clk.h>
41#include <linux/io.h>
42#include <linux/log2.h>
43#include <linux/module.h>
44#include <linux/mod_devicetable.h>
45#include <linux/platform_device.h>
46#include <linux/slab.h>
47#include <linux/watchdog.h>
48
49/* registers */
50#define PDC_WDT_SOFT_RESET 0x00
51#define PDC_WDT_CONFIG 0x04
52 #define PDC_WDT_CONFIG_ENABLE BIT(31)
53 #define PDC_WDT_CONFIG_DELAY_MASK 0x1f
54
55#define PDC_WDT_TICKLE1 0x08
56#define PDC_WDT_TICKLE1_MAGIC 0xabcd1234
57#define PDC_WDT_TICKLE2 0x0c
58#define PDC_WDT_TICKLE2_MAGIC 0x4321dcba
59
60#define PDC_WDT_TICKLE_STATUS_MASK 0x7
61#define PDC_WDT_TICKLE_STATUS_SHIFT 0
62#define PDC_WDT_TICKLE_STATUS_HRESET 0x0 /* Hard reset */
63#define PDC_WDT_TICKLE_STATUS_TIMEOUT 0x1 /* Timeout */
64#define PDC_WDT_TICKLE_STATUS_TICKLE 0x2 /* Tickled incorrectly */
65#define PDC_WDT_TICKLE_STATUS_SRESET 0x3 /* Soft reset */
66#define PDC_WDT_TICKLE_STATUS_USER 0x4 /* User reset */
67
68/* Timeout values are in seconds */
69#define PDC_WDT_MIN_TIMEOUT 1
70#define PDC_WDT_DEF_TIMEOUT 64
71
72static int heartbeat;
73module_param(heartbeat, int, 0);
74MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds "
75 "(default=" __MODULE_STRING(PDC_WDT_DEF_TIMEOUT) ")");
76
77static bool nowayout = WATCHDOG_NOWAYOUT;
78module_param(nowayout, bool, 0);
79MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
80 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
81
82struct pdc_wdt_dev {
83 struct watchdog_device wdt_dev;
84 struct clk *wdt_clk;
85 struct clk *sys_clk;
86 void __iomem *base;
87};
88
89static int pdc_wdt_keepalive(struct watchdog_device *wdt_dev)
90{
91 struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
92
93 writel(PDC_WDT_TICKLE1_MAGIC, wdt->base + PDC_WDT_TICKLE1);
94 writel(PDC_WDT_TICKLE2_MAGIC, wdt->base + PDC_WDT_TICKLE2);
95
96 return 0;
97}
98
99static int pdc_wdt_stop(struct watchdog_device *wdt_dev)
100{
101 unsigned int val;
102 struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
103
104 val = readl(wdt->base + PDC_WDT_CONFIG);
105 val &= ~PDC_WDT_CONFIG_ENABLE;
106 writel(val, wdt->base + PDC_WDT_CONFIG);
107
108 /* Must tickle to finish the stop */
109 pdc_wdt_keepalive(wdt_dev);
110
111 return 0;
112}
113
114static void __pdc_wdt_set_timeout(struct pdc_wdt_dev *wdt)
115{
116 unsigned long clk_rate = clk_get_rate(wdt->wdt_clk);
117 unsigned int val;
118
119 val = readl(wdt->base + PDC_WDT_CONFIG) & ~PDC_WDT_CONFIG_DELAY_MASK;
120 val |= order_base_2(wdt->wdt_dev.timeout * clk_rate) - 1;
121 writel(val, wdt->base + PDC_WDT_CONFIG);
122}
123
124static int pdc_wdt_set_timeout(struct watchdog_device *wdt_dev,
125 unsigned int new_timeout)
126{
127 struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
128
129 wdt->wdt_dev.timeout = new_timeout;
130
131 __pdc_wdt_set_timeout(wdt);
132
133 return 0;
134}
135
136/* Start the watchdog timer (delay should already be set) */
137static int pdc_wdt_start(struct watchdog_device *wdt_dev)
138{
139 unsigned int val;
140 struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
141
142 __pdc_wdt_set_timeout(wdt);
143
144 val = readl(wdt->base + PDC_WDT_CONFIG);
145 val |= PDC_WDT_CONFIG_ENABLE;
146 writel(val, wdt->base + PDC_WDT_CONFIG);
147
148 return 0;
149}
150
151static int pdc_wdt_restart(struct watchdog_device *wdt_dev,
152 unsigned long action, void *data)
153{
154 struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
155
156 /* Assert SOFT_RESET */
157 writel(0x1, wdt->base + PDC_WDT_SOFT_RESET);
158
159 return 0;
160}
161
162static const struct watchdog_info pdc_wdt_info = {
163 .identity = "IMG PDC Watchdog",
164 .options = WDIOF_SETTIMEOUT |
165 WDIOF_KEEPALIVEPING |
166 WDIOF_MAGICCLOSE,
167};
168
169static const struct watchdog_ops pdc_wdt_ops = {
170 .owner = THIS_MODULE,
171 .start = pdc_wdt_start,
172 .stop = pdc_wdt_stop,
173 .ping = pdc_wdt_keepalive,
174 .set_timeout = pdc_wdt_set_timeout,
175 .restart = pdc_wdt_restart,
176};
177
178static int pdc_wdt_probe(struct platform_device *pdev)
179{
180 struct device *dev = &pdev->dev;
181 u64 div;
182 int val;
183 unsigned long clk_rate;
184 struct pdc_wdt_dev *pdc_wdt;
185
186 pdc_wdt = devm_kzalloc(dev, sizeof(*pdc_wdt), GFP_KERNEL);
187 if (!pdc_wdt)
188 return -ENOMEM;
189
190 pdc_wdt->base = devm_platform_ioremap_resource(pdev, 0);
191 if (IS_ERR(pdc_wdt->base))
192 return PTR_ERR(pdc_wdt->base);
193
194 pdc_wdt->sys_clk = devm_clk_get_enabled(dev, "sys");
195 if (IS_ERR(pdc_wdt->sys_clk)) {
196 dev_err(dev, "failed to get the sys clock\n");
197 return PTR_ERR(pdc_wdt->sys_clk);
198 }
199
200 pdc_wdt->wdt_clk = devm_clk_get_enabled(dev, "wdt");
201 if (IS_ERR(pdc_wdt->wdt_clk)) {
202 dev_err(dev, "failed to get the wdt clock\n");
203 return PTR_ERR(pdc_wdt->wdt_clk);
204 }
205
206 /* We use the clock rate to calculate the max timeout */
207 clk_rate = clk_get_rate(pdc_wdt->wdt_clk);
208 if (clk_rate == 0) {
209 dev_err(dev, "failed to get clock rate\n");
210 return -EINVAL;
211 }
212
213 if (order_base_2(clk_rate) > PDC_WDT_CONFIG_DELAY_MASK + 1) {
214 dev_err(dev, "invalid clock rate\n");
215 return -EINVAL;
216 }
217
218 if (order_base_2(clk_rate) == 0)
219 pdc_wdt->wdt_dev.min_timeout = PDC_WDT_MIN_TIMEOUT + 1;
220 else
221 pdc_wdt->wdt_dev.min_timeout = PDC_WDT_MIN_TIMEOUT;
222
223 pdc_wdt->wdt_dev.info = &pdc_wdt_info;
224 pdc_wdt->wdt_dev.ops = &pdc_wdt_ops;
225
226 div = 1ULL << (PDC_WDT_CONFIG_DELAY_MASK + 1);
227 do_div(div, clk_rate);
228 pdc_wdt->wdt_dev.max_timeout = div;
229 pdc_wdt->wdt_dev.timeout = PDC_WDT_DEF_TIMEOUT;
230 pdc_wdt->wdt_dev.parent = dev;
231 watchdog_set_drvdata(&pdc_wdt->wdt_dev, pdc_wdt);
232
233 watchdog_init_timeout(&pdc_wdt->wdt_dev, heartbeat, dev);
234
235 pdc_wdt_stop(&pdc_wdt->wdt_dev);
236
237 /* Find what caused the last reset */
238 val = readl(pdc_wdt->base + PDC_WDT_TICKLE1);
239 val = (val & PDC_WDT_TICKLE_STATUS_MASK) >> PDC_WDT_TICKLE_STATUS_SHIFT;
240 switch (val) {
241 case PDC_WDT_TICKLE_STATUS_TICKLE:
242 case PDC_WDT_TICKLE_STATUS_TIMEOUT:
243 pdc_wdt->wdt_dev.bootstatus |= WDIOF_CARDRESET;
244 dev_info(dev, "watchdog module last reset due to timeout\n");
245 break;
246 case PDC_WDT_TICKLE_STATUS_HRESET:
247 dev_info(dev,
248 "watchdog module last reset due to hard reset\n");
249 break;
250 case PDC_WDT_TICKLE_STATUS_SRESET:
251 dev_info(dev,
252 "watchdog module last reset due to soft reset\n");
253 break;
254 case PDC_WDT_TICKLE_STATUS_USER:
255 dev_info(dev,
256 "watchdog module last reset due to user reset\n");
257 break;
258 default:
259 dev_info(dev, "contains an illegal status code (%08x)\n", val);
260 break;
261 }
262
263 watchdog_set_nowayout(&pdc_wdt->wdt_dev, nowayout);
264 watchdog_set_restart_priority(&pdc_wdt->wdt_dev, 128);
265
266 platform_set_drvdata(pdev, pdc_wdt);
267
268 watchdog_stop_on_reboot(&pdc_wdt->wdt_dev);
269 watchdog_stop_on_unregister(&pdc_wdt->wdt_dev);
270 return devm_watchdog_register_device(dev, &pdc_wdt->wdt_dev);
271}
272
273static const struct of_device_id pdc_wdt_match[] = {
274 { .compatible = "img,pdc-wdt" },
275 {}
276};
277MODULE_DEVICE_TABLE(of, pdc_wdt_match);
278
279static struct platform_driver pdc_wdt_driver = {
280 .driver = {
281 .name = "imgpdc-wdt",
282 .of_match_table = pdc_wdt_match,
283 },
284 .probe = pdc_wdt_probe,
285};
286module_platform_driver(pdc_wdt_driver);
287
288MODULE_AUTHOR("Jude Abraham <Jude.Abraham@imgtec.com>");
289MODULE_AUTHOR("Naidu Tellapati <Naidu.Tellapati@imgtec.com>");
290MODULE_DESCRIPTION("Imagination Technologies PDC Watchdog Timer Driver");
291MODULE_LICENSE("GPL v2");