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 
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 
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 
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 
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 
154 static void xwdt_clk_disable_unprepare(void *data)
155 {
156 	clk_disable_unprepare(data);
157 }
158 
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 		dev_err(dev, "Cannot register watchdog (err=%d)\n", rc);
243 		return rc;
244 	}
245 
246 	clk_disable(xdev->clk);
247 
248 	dev_info(dev, "Xilinx Watchdog Timer at %p with timeout %ds\n",
249 		 xdev->base, xilinx_wdt_wdd->timeout);
250 
251 	platform_set_drvdata(pdev, xdev);
252 
253 	return 0;
254 }
255 
256 /**
257  * xwdt_suspend - Suspend the device.
258  *
259  * @dev: handle to the device structure.
260  * Return: 0 always.
261  */
262 static int __maybe_unused xwdt_suspend(struct device *dev)
263 {
264 	struct xwdt_device *xdev = dev_get_drvdata(dev);
265 
266 	if (watchdog_active(&xdev->xilinx_wdt_wdd))
267 		xilinx_wdt_stop(&xdev->xilinx_wdt_wdd);
268 
269 	return 0;
270 }
271 
272 /**
273  * xwdt_resume - Resume the device.
274  *
275  * @dev: handle to the device structure.
276  * Return: 0 on success, errno otherwise.
277  */
278 static int __maybe_unused xwdt_resume(struct device *dev)
279 {
280 	struct xwdt_device *xdev = dev_get_drvdata(dev);
281 	int ret = 0;
282 
283 	if (watchdog_active(&xdev->xilinx_wdt_wdd))
284 		ret = xilinx_wdt_start(&xdev->xilinx_wdt_wdd);
285 
286 	return ret;
287 }
288 
289 static SIMPLE_DEV_PM_OPS(xwdt_pm_ops, xwdt_suspend, xwdt_resume);
290 
291 /* Match table for of_platform binding */
292 static const struct of_device_id xwdt_of_match[] = {
293 	{ .compatible = "xlnx,xps-timebase-wdt-1.00.a", },
294 	{ .compatible = "xlnx,xps-timebase-wdt-1.01.a", },
295 	{},
296 };
297 MODULE_DEVICE_TABLE(of, xwdt_of_match);
298 
299 static struct platform_driver xwdt_driver = {
300 	.probe       = xwdt_probe,
301 	.driver = {
302 		.name  = WATCHDOG_NAME,
303 		.of_match_table = xwdt_of_match,
304 		.pm = &xwdt_pm_ops,
305 	},
306 };
307 
308 module_platform_driver(xwdt_driver);
309 
310 MODULE_AUTHOR("Alejandro Cabrera <aldaya@gmail.com>");
311 MODULE_DESCRIPTION("Xilinx Watchdog driver");
312 MODULE_LICENSE("GPL");
313