1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Watchdog Device Driver for Xilinx axi/xps_timebase_wdt
4 *
5 * (C) Copyright 2013 - 2014 Xilinx, Inc.
6 * (C) Copyright 2011 (Alejandro Cabrera <aldaya@gmail.com>)
7 */
8
9 #include <linux/clk.h>
10 #include <linux/err.h>
11 #include <linux/module.h>
12 #include <linux/types.h>
13 #include <linux/kernel.h>
14 #include <linux/ioport.h>
15 #include <linux/watchdog.h>
16 #include <linux/io.h>
17 #include <linux/of.h>
18 #include <linux/of_device.h>
19 #include <linux/of_address.h>
20
21 /* Register offsets for the Wdt device */
22 #define XWT_TWCSR0_OFFSET 0x0 /* Control/Status Register0 */
23 #define XWT_TWCSR1_OFFSET 0x4 /* Control/Status Register1 */
24 #define XWT_TBR_OFFSET 0x8 /* Timebase Register Offset */
25
26 /* Control/Status Register Masks */
27 #define XWT_CSR0_WRS_MASK 0x00000008 /* Reset status */
28 #define XWT_CSR0_WDS_MASK 0x00000004 /* Timer state */
29 #define XWT_CSR0_EWDT1_MASK 0x00000002 /* Enable bit 1 */
30
31 /* Control/Status Register 0/1 bits */
32 #define XWT_CSRX_EWDT2_MASK 0x00000001 /* Enable bit 2 */
33
34 /* SelfTest constants */
35 #define XWT_MAX_SELFTEST_LOOP_COUNT 0x00010000
36 #define XWT_TIMER_FAILED 0xFFFFFFFF
37
38 #define WATCHDOG_NAME "Xilinx Watchdog"
39
40 struct xwdt_device {
41 void __iomem *base;
42 u32 wdt_interval;
43 spinlock_t spinlock;
44 struct watchdog_device xilinx_wdt_wdd;
45 struct clk *clk;
46 };
47
xilinx_wdt_start(struct watchdog_device * wdd)48 static int xilinx_wdt_start(struct watchdog_device *wdd)
49 {
50 int ret;
51 u32 control_status_reg;
52 struct xwdt_device *xdev = watchdog_get_drvdata(wdd);
53
54 ret = clk_enable(xdev->clk);
55 if (ret) {
56 dev_err(wdd->parent, "Failed to enable clock\n");
57 return ret;
58 }
59
60 spin_lock(&xdev->spinlock);
61
62 /* Clean previous status and enable the watchdog timer */
63 control_status_reg = ioread32(xdev->base + XWT_TWCSR0_OFFSET);
64 control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
65
66 iowrite32((control_status_reg | XWT_CSR0_EWDT1_MASK),
67 xdev->base + XWT_TWCSR0_OFFSET);
68
69 iowrite32(XWT_CSRX_EWDT2_MASK, xdev->base + XWT_TWCSR1_OFFSET);
70
71 spin_unlock(&xdev->spinlock);
72
73 return 0;
74 }
75
xilinx_wdt_stop(struct watchdog_device * wdd)76 static int xilinx_wdt_stop(struct watchdog_device *wdd)
77 {
78 u32 control_status_reg;
79 struct xwdt_device *xdev = watchdog_get_drvdata(wdd);
80
81 spin_lock(&xdev->spinlock);
82
83 control_status_reg = ioread32(xdev->base + XWT_TWCSR0_OFFSET);
84
85 iowrite32((control_status_reg & ~XWT_CSR0_EWDT1_MASK),
86 xdev->base + XWT_TWCSR0_OFFSET);
87
88 iowrite32(0, xdev->base + XWT_TWCSR1_OFFSET);
89
90 spin_unlock(&xdev->spinlock);
91
92 clk_disable(xdev->clk);
93
94 pr_info("Stopped!\n");
95
96 return 0;
97 }
98
xilinx_wdt_keepalive(struct watchdog_device * wdd)99 static int xilinx_wdt_keepalive(struct watchdog_device *wdd)
100 {
101 u32 control_status_reg;
102 struct xwdt_device *xdev = watchdog_get_drvdata(wdd);
103
104 spin_lock(&xdev->spinlock);
105
106 control_status_reg = ioread32(xdev->base + XWT_TWCSR0_OFFSET);
107 control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
108 iowrite32(control_status_reg, xdev->base + XWT_TWCSR0_OFFSET);
109
110 spin_unlock(&xdev->spinlock);
111
112 return 0;
113 }
114
115 static const struct watchdog_info xilinx_wdt_ident = {
116 .options = WDIOF_MAGICCLOSE |
117 WDIOF_KEEPALIVEPING,
118 .firmware_version = 1,
119 .identity = WATCHDOG_NAME,
120 };
121
122 static const struct watchdog_ops xilinx_wdt_ops = {
123 .owner = THIS_MODULE,
124 .start = xilinx_wdt_start,
125 .stop = xilinx_wdt_stop,
126 .ping = xilinx_wdt_keepalive,
127 };
128
xwdt_selftest(struct xwdt_device * xdev)129 static u32 xwdt_selftest(struct xwdt_device *xdev)
130 {
131 int i;
132 u32 timer_value1;
133 u32 timer_value2;
134
135 spin_lock(&xdev->spinlock);
136
137 timer_value1 = ioread32(xdev->base + XWT_TBR_OFFSET);
138 timer_value2 = ioread32(xdev->base + XWT_TBR_OFFSET);
139
140 for (i = 0;
141 ((i <= XWT_MAX_SELFTEST_LOOP_COUNT) &&
142 (timer_value2 == timer_value1)); i++) {
143 timer_value2 = ioread32(xdev->base + XWT_TBR_OFFSET);
144 }
145
146 spin_unlock(&xdev->spinlock);
147
148 if (timer_value2 != timer_value1)
149 return ~XWT_TIMER_FAILED;
150 else
151 return XWT_TIMER_FAILED;
152 }
153
xwdt_clk_disable_unprepare(void * data)154 static void xwdt_clk_disable_unprepare(void *data)
155 {
156 clk_disable_unprepare(data);
157 }
158
xwdt_probe(struct platform_device * pdev)159 static int xwdt_probe(struct platform_device *pdev)
160 {
161 struct device *dev = &pdev->dev;
162 int rc;
163 u32 pfreq = 0, enable_once = 0;
164 struct xwdt_device *xdev;
165 struct watchdog_device *xilinx_wdt_wdd;
166
167 xdev = devm_kzalloc(dev, sizeof(*xdev), GFP_KERNEL);
168 if (!xdev)
169 return -ENOMEM;
170
171 xilinx_wdt_wdd = &xdev->xilinx_wdt_wdd;
172 xilinx_wdt_wdd->info = &xilinx_wdt_ident;
173 xilinx_wdt_wdd->ops = &xilinx_wdt_ops;
174 xilinx_wdt_wdd->parent = dev;
175
176 xdev->base = devm_platform_ioremap_resource(pdev, 0);
177 if (IS_ERR(xdev->base))
178 return PTR_ERR(xdev->base);
179
180 rc = of_property_read_u32(dev->of_node, "xlnx,wdt-interval",
181 &xdev->wdt_interval);
182 if (rc)
183 dev_warn(dev, "Parameter \"xlnx,wdt-interval\" not found\n");
184
185 rc = of_property_read_u32(dev->of_node, "xlnx,wdt-enable-once",
186 &enable_once);
187 if (rc)
188 dev_warn(dev,
189 "Parameter \"xlnx,wdt-enable-once\" not found\n");
190
191 watchdog_set_nowayout(xilinx_wdt_wdd, enable_once);
192
193 xdev->clk = devm_clk_get(dev, NULL);
194 if (IS_ERR(xdev->clk)) {
195 if (PTR_ERR(xdev->clk) != -ENOENT)
196 return PTR_ERR(xdev->clk);
197
198 /*
199 * Clock framework support is optional, continue on
200 * anyways if we don't find a matching clock.
201 */
202 xdev->clk = NULL;
203
204 rc = of_property_read_u32(dev->of_node, "clock-frequency",
205 &pfreq);
206 if (rc)
207 dev_warn(dev,
208 "The watchdog clock freq cannot be obtained\n");
209 } else {
210 pfreq = clk_get_rate(xdev->clk);
211 }
212
213 /*
214 * Twice of the 2^wdt_interval / freq because the first wdt overflow is
215 * ignored (interrupt), reset is only generated at second wdt overflow
216 */
217 if (pfreq && xdev->wdt_interval)
218 xilinx_wdt_wdd->timeout = 2 * ((1 << xdev->wdt_interval) /
219 pfreq);
220
221 spin_lock_init(&xdev->spinlock);
222 watchdog_set_drvdata(xilinx_wdt_wdd, xdev);
223
224 rc = clk_prepare_enable(xdev->clk);
225 if (rc) {
226 dev_err(dev, "unable to enable clock\n");
227 return rc;
228 }
229 rc = devm_add_action_or_reset(dev, xwdt_clk_disable_unprepare,
230 xdev->clk);
231 if (rc)
232 return rc;
233
234 rc = xwdt_selftest(xdev);
235 if (rc == XWT_TIMER_FAILED) {
236 dev_err(dev, "SelfTest routine error\n");
237 return rc;
238 }
239
240 rc = devm_watchdog_register_device(dev, xilinx_wdt_wdd);
241 if (rc)
242 return rc;
243
244 clk_disable(xdev->clk);
245
246 dev_info(dev, "Xilinx Watchdog Timer at %p with timeout %ds\n",
247 xdev->base, xilinx_wdt_wdd->timeout);
248
249 platform_set_drvdata(pdev, xdev);
250
251 return 0;
252 }
253
254 /**
255 * xwdt_suspend - Suspend the device.
256 *
257 * @dev: handle to the device structure.
258 * Return: 0 always.
259 */
xwdt_suspend(struct device * dev)260 static int __maybe_unused xwdt_suspend(struct device *dev)
261 {
262 struct xwdt_device *xdev = dev_get_drvdata(dev);
263
264 if (watchdog_active(&xdev->xilinx_wdt_wdd))
265 xilinx_wdt_stop(&xdev->xilinx_wdt_wdd);
266
267 return 0;
268 }
269
270 /**
271 * xwdt_resume - Resume the device.
272 *
273 * @dev: handle to the device structure.
274 * Return: 0 on success, errno otherwise.
275 */
xwdt_resume(struct device * dev)276 static int __maybe_unused xwdt_resume(struct device *dev)
277 {
278 struct xwdt_device *xdev = dev_get_drvdata(dev);
279 int ret = 0;
280
281 if (watchdog_active(&xdev->xilinx_wdt_wdd))
282 ret = xilinx_wdt_start(&xdev->xilinx_wdt_wdd);
283
284 return ret;
285 }
286
287 static SIMPLE_DEV_PM_OPS(xwdt_pm_ops, xwdt_suspend, xwdt_resume);
288
289 /* Match table for of_platform binding */
290 static const struct of_device_id xwdt_of_match[] = {
291 { .compatible = "xlnx,xps-timebase-wdt-1.00.a", },
292 { .compatible = "xlnx,xps-timebase-wdt-1.01.a", },
293 {},
294 };
295 MODULE_DEVICE_TABLE(of, xwdt_of_match);
296
297 static struct platform_driver xwdt_driver = {
298 .probe = xwdt_probe,
299 .driver = {
300 .name = WATCHDOG_NAME,
301 .of_match_table = xwdt_of_match,
302 .pm = &xwdt_pm_ops,
303 },
304 };
305
306 module_platform_driver(xwdt_driver);
307
308 MODULE_AUTHOR("Alejandro Cabrera <aldaya@gmail.com>");
309 MODULE_DESCRIPTION("Xilinx Watchdog driver");
310 MODULE_LICENSE("GPL");
311
