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/bits.h>
10 #include <linux/clk.h>
11 #include <linux/err.h>
12 #include <linux/module.h>
13 #include <linux/platform_device.h>
14 #include <linux/types.h>
15 #include <linux/kernel.h>
16 #include <linux/ioport.h>
17 #include <linux/watchdog.h>
18 #include <linux/io.h>
19 #include <linux/of.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 BIT(3) /* Reset status */
28 #define XWT_CSR0_WDS_MASK BIT(2) /* Timer state */
29 #define XWT_CSR0_EWDT1_MASK BIT(1) /* Enable bit 1 */
30
31 /* Control/Status Register 0/1 bits */
32 #define XWT_CSRX_EWDT2_MASK BIT(0) /* 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; /* spinlock for register handling */
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 dev_dbg(wdd->parent, "Watchdog Started!\n");
74
75 return 0;
76 }
77
xilinx_wdt_stop(struct watchdog_device * wdd)78 static int xilinx_wdt_stop(struct watchdog_device *wdd)
79 {
80 u32 control_status_reg;
81 struct xwdt_device *xdev = watchdog_get_drvdata(wdd);
82
83 spin_lock(&xdev->spinlock);
84
85 control_status_reg = ioread32(xdev->base + XWT_TWCSR0_OFFSET);
86
87 iowrite32((control_status_reg & ~XWT_CSR0_EWDT1_MASK),
88 xdev->base + XWT_TWCSR0_OFFSET);
89
90 iowrite32(0, xdev->base + XWT_TWCSR1_OFFSET);
91
92 spin_unlock(&xdev->spinlock);
93
94 clk_disable(xdev->clk);
95
96 dev_dbg(wdd->parent, "Watchdog Stopped!\n");
97
98 return 0;
99 }
100
xilinx_wdt_keepalive(struct watchdog_device * wdd)101 static int xilinx_wdt_keepalive(struct watchdog_device *wdd)
102 {
103 u32 control_status_reg;
104 struct xwdt_device *xdev = watchdog_get_drvdata(wdd);
105
106 spin_lock(&xdev->spinlock);
107
108 control_status_reg = ioread32(xdev->base + XWT_TWCSR0_OFFSET);
109 control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
110 iowrite32(control_status_reg, xdev->base + XWT_TWCSR0_OFFSET);
111
112 spin_unlock(&xdev->spinlock);
113
114 return 0;
115 }
116
117 static const struct watchdog_info xilinx_wdt_ident = {
118 .options = WDIOF_MAGICCLOSE |
119 WDIOF_KEEPALIVEPING,
120 .firmware_version = 1,
121 .identity = WATCHDOG_NAME,
122 };
123
124 static const struct watchdog_ops xilinx_wdt_ops = {
125 .owner = THIS_MODULE,
126 .start = xilinx_wdt_start,
127 .stop = xilinx_wdt_stop,
128 .ping = xilinx_wdt_keepalive,
129 };
130
xwdt_selftest(struct xwdt_device * xdev)131 static u32 xwdt_selftest(struct xwdt_device *xdev)
132 {
133 int i;
134 u32 timer_value1;
135 u32 timer_value2;
136
137 spin_lock(&xdev->spinlock);
138
139 timer_value1 = ioread32(xdev->base + XWT_TBR_OFFSET);
140 timer_value2 = ioread32(xdev->base + XWT_TBR_OFFSET);
141
142 for (i = 0;
143 ((i <= XWT_MAX_SELFTEST_LOOP_COUNT) &&
144 (timer_value2 == timer_value1)); i++) {
145 timer_value2 = ioread32(xdev->base + XWT_TBR_OFFSET);
146 }
147
148 spin_unlock(&xdev->spinlock);
149
150 if (timer_value2 != timer_value1)
151 return ~XWT_TIMER_FAILED;
152 else
153 return XWT_TIMER_FAILED;
154 }
155
xwdt_probe(struct platform_device * pdev)156 static int xwdt_probe(struct platform_device *pdev)
157 {
158 struct device *dev = &pdev->dev;
159 int rc;
160 u32 pfreq = 0, enable_once = 0;
161 struct xwdt_device *xdev;
162 struct watchdog_device *xilinx_wdt_wdd;
163
164 xdev = devm_kzalloc(dev, sizeof(*xdev), GFP_KERNEL);
165 if (!xdev)
166 return -ENOMEM;
167
168 xilinx_wdt_wdd = &xdev->xilinx_wdt_wdd;
169 xilinx_wdt_wdd->info = &xilinx_wdt_ident;
170 xilinx_wdt_wdd->ops = &xilinx_wdt_ops;
171 xilinx_wdt_wdd->parent = dev;
172
173 xdev->base = devm_platform_ioremap_resource(pdev, 0);
174 if (IS_ERR(xdev->base))
175 return PTR_ERR(xdev->base);
176
177 rc = of_property_read_u32(dev->of_node, "xlnx,wdt-interval",
178 &xdev->wdt_interval);
179 if (rc)
180 dev_warn(dev, "Parameter \"xlnx,wdt-interval\" not found\n");
181
182 rc = of_property_read_u32(dev->of_node, "xlnx,wdt-enable-once",
183 &enable_once);
184 if (rc)
185 dev_warn(dev,
186 "Parameter \"xlnx,wdt-enable-once\" not found\n");
187
188 watchdog_set_nowayout(xilinx_wdt_wdd, enable_once);
189
190 xdev->clk = devm_clk_get_enabled(dev, NULL);
191 if (IS_ERR(xdev->clk)) {
192 if (PTR_ERR(xdev->clk) != -ENOENT)
193 return PTR_ERR(xdev->clk);
194
195 /*
196 * Clock framework support is optional, continue on
197 * anyways if we don't find a matching clock.
198 */
199 xdev->clk = NULL;
200
201 rc = of_property_read_u32(dev->of_node, "clock-frequency",
202 &pfreq);
203 if (rc)
204 dev_warn(dev,
205 "The watchdog clock freq cannot be obtained\n");
206 } else {
207 pfreq = clk_get_rate(xdev->clk);
208 }
209
210 /*
211 * Twice of the 2^wdt_interval / freq because the first wdt overflow is
212 * ignored (interrupt), reset is only generated at second wdt overflow
213 */
214 if (pfreq && xdev->wdt_interval)
215 xilinx_wdt_wdd->timeout = 2 * ((1 << xdev->wdt_interval) /
216 pfreq);
217
218 spin_lock_init(&xdev->spinlock);
219 watchdog_set_drvdata(xilinx_wdt_wdd, xdev);
220
221 rc = xwdt_selftest(xdev);
222 if (rc == XWT_TIMER_FAILED) {
223 dev_err(dev, "SelfTest routine error\n");
224 return rc;
225 }
226
227 rc = devm_watchdog_register_device(dev, xilinx_wdt_wdd);
228 if (rc)
229 return rc;
230
231 clk_disable(xdev->clk);
232
233 dev_info(dev, "Xilinx Watchdog Timer with timeout %ds\n",
234 xilinx_wdt_wdd->timeout);
235
236 platform_set_drvdata(pdev, xdev);
237
238 return 0;
239 }
240
241 /**
242 * xwdt_suspend - Suspend the device.
243 *
244 * @dev: handle to the device structure.
245 * Return: 0 always.
246 */
xwdt_suspend(struct device * dev)247 static int __maybe_unused xwdt_suspend(struct device *dev)
248 {
249 struct xwdt_device *xdev = dev_get_drvdata(dev);
250
251 if (watchdog_active(&xdev->xilinx_wdt_wdd))
252 xilinx_wdt_stop(&xdev->xilinx_wdt_wdd);
253
254 return 0;
255 }
256
257 /**
258 * xwdt_resume - Resume the device.
259 *
260 * @dev: handle to the device structure.
261 * Return: 0 on success, errno otherwise.
262 */
xwdt_resume(struct device * dev)263 static int __maybe_unused xwdt_resume(struct device *dev)
264 {
265 struct xwdt_device *xdev = dev_get_drvdata(dev);
266 int ret = 0;
267
268 if (watchdog_active(&xdev->xilinx_wdt_wdd))
269 ret = xilinx_wdt_start(&xdev->xilinx_wdt_wdd);
270
271 return ret;
272 }
273
274 static SIMPLE_DEV_PM_OPS(xwdt_pm_ops, xwdt_suspend, xwdt_resume);
275
276 /* Match table for of_platform binding */
277 static const struct of_device_id xwdt_of_match[] = {
278 { .compatible = "xlnx,xps-timebase-wdt-1.00.a", },
279 { .compatible = "xlnx,xps-timebase-wdt-1.01.a", },
280 {},
281 };
282 MODULE_DEVICE_TABLE(of, xwdt_of_match);
283
284 static struct platform_driver xwdt_driver = {
285 .probe = xwdt_probe,
286 .driver = {
287 .name = WATCHDOG_NAME,
288 .of_match_table = xwdt_of_match,
289 .pm = &xwdt_pm_ops,
290 },
291 };
292
293 module_platform_driver(xwdt_driver);
294
295 MODULE_AUTHOR("Alejandro Cabrera <aldaya@gmail.com>");
296 MODULE_DESCRIPTION("Xilinx Watchdog driver");
297 MODULE_LICENSE("GPL");
298
