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/types.h>
14 #include <linux/kernel.h>
15 #include <linux/ioport.h>
16 #include <linux/watchdog.h>
17 #include <linux/io.h>
18 #include <linux/of.h>
19 #include <linux/of_device.h>
20 #include <linux/of_address.h>
21 
22 /* Register offsets for the Wdt device */
23 #define XWT_TWCSR0_OFFSET   0x0 /* Control/Status Register0 */
24 #define XWT_TWCSR1_OFFSET   0x4 /* Control/Status Register1 */
25 #define XWT_TBR_OFFSET      0x8 /* Timebase Register Offset */
26 
27 /* Control/Status Register Masks  */
28 #define XWT_CSR0_WRS_MASK	BIT(3) /* Reset status */
29 #define XWT_CSR0_WDS_MASK	BIT(2) /* Timer state  */
30 #define XWT_CSR0_EWDT1_MASK	BIT(1) /* Enable bit 1 */
31 
32 /* Control/Status Register 0/1 bits  */
33 #define XWT_CSRX_EWDT2_MASK	BIT(0) /* Enable bit 2 */
34 
35 /* SelfTest constants */
36 #define XWT_MAX_SELFTEST_LOOP_COUNT 0x00010000
37 #define XWT_TIMER_FAILED            0xFFFFFFFF
38 
39 #define WATCHDOG_NAME     "Xilinx Watchdog"
40 
41 struct xwdt_device {
42 	void __iomem *base;
43 	u32 wdt_interval;
44 	spinlock_t spinlock; /* spinlock for register handling */
45 	struct watchdog_device xilinx_wdt_wdd;
46 	struct clk		*clk;
47 };
48 
49 static int xilinx_wdt_start(struct watchdog_device *wdd)
50 {
51 	int ret;
52 	u32 control_status_reg;
53 	struct xwdt_device *xdev = watchdog_get_drvdata(wdd);
54 
55 	ret = clk_enable(xdev->clk);
56 	if (ret) {
57 		dev_err(wdd->parent, "Failed to enable clock\n");
58 		return ret;
59 	}
60 
61 	spin_lock(&xdev->spinlock);
62 
63 	/* Clean previous status and enable the watchdog timer */
64 	control_status_reg = ioread32(xdev->base + XWT_TWCSR0_OFFSET);
65 	control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
66 
67 	iowrite32((control_status_reg | XWT_CSR0_EWDT1_MASK),
68 		  xdev->base + XWT_TWCSR0_OFFSET);
69 
70 	iowrite32(XWT_CSRX_EWDT2_MASK, xdev->base + XWT_TWCSR1_OFFSET);
71 
72 	spin_unlock(&xdev->spinlock);
73 
74 	dev_dbg(wdd->parent, "Watchdog Started!\n");
75 
76 	return 0;
77 }
78 
79 static int xilinx_wdt_stop(struct watchdog_device *wdd)
80 {
81 	u32 control_status_reg;
82 	struct xwdt_device *xdev = watchdog_get_drvdata(wdd);
83 
84 	spin_lock(&xdev->spinlock);
85 
86 	control_status_reg = ioread32(xdev->base + XWT_TWCSR0_OFFSET);
87 
88 	iowrite32((control_status_reg & ~XWT_CSR0_EWDT1_MASK),
89 		  xdev->base + XWT_TWCSR0_OFFSET);
90 
91 	iowrite32(0, xdev->base + XWT_TWCSR1_OFFSET);
92 
93 	spin_unlock(&xdev->spinlock);
94 
95 	clk_disable(xdev->clk);
96 
97 	dev_dbg(wdd->parent, "Watchdog Stopped!\n");
98 
99 	return 0;
100 }
101 
102 static int xilinx_wdt_keepalive(struct watchdog_device *wdd)
103 {
104 	u32 control_status_reg;
105 	struct xwdt_device *xdev = watchdog_get_drvdata(wdd);
106 
107 	spin_lock(&xdev->spinlock);
108 
109 	control_status_reg = ioread32(xdev->base + XWT_TWCSR0_OFFSET);
110 	control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
111 	iowrite32(control_status_reg, xdev->base + XWT_TWCSR0_OFFSET);
112 
113 	spin_unlock(&xdev->spinlock);
114 
115 	return 0;
116 }
117 
118 static const struct watchdog_info xilinx_wdt_ident = {
119 	.options =  WDIOF_MAGICCLOSE |
120 		    WDIOF_KEEPALIVEPING,
121 	.firmware_version =	1,
122 	.identity =	WATCHDOG_NAME,
123 };
124 
125 static const struct watchdog_ops xilinx_wdt_ops = {
126 	.owner = THIS_MODULE,
127 	.start = xilinx_wdt_start,
128 	.stop = xilinx_wdt_stop,
129 	.ping = xilinx_wdt_keepalive,
130 };
131 
132 static u32 xwdt_selftest(struct xwdt_device *xdev)
133 {
134 	int i;
135 	u32 timer_value1;
136 	u32 timer_value2;
137 
138 	spin_lock(&xdev->spinlock);
139 
140 	timer_value1 = ioread32(xdev->base + XWT_TBR_OFFSET);
141 	timer_value2 = ioread32(xdev->base + XWT_TBR_OFFSET);
142 
143 	for (i = 0;
144 		((i <= XWT_MAX_SELFTEST_LOOP_COUNT) &&
145 			(timer_value2 == timer_value1)); i++) {
146 		timer_value2 = ioread32(xdev->base + XWT_TBR_OFFSET);
147 	}
148 
149 	spin_unlock(&xdev->spinlock);
150 
151 	if (timer_value2 != timer_value1)
152 		return ~XWT_TIMER_FAILED;
153 	else
154 		return XWT_TIMER_FAILED;
155 }
156 
157 static void xwdt_clk_disable_unprepare(void *data)
158 {
159 	clk_disable_unprepare(data);
160 }
161 
162 static int xwdt_probe(struct platform_device *pdev)
163 {
164 	struct device *dev = &pdev->dev;
165 	int rc;
166 	u32 pfreq = 0, enable_once = 0;
167 	struct xwdt_device *xdev;
168 	struct watchdog_device *xilinx_wdt_wdd;
169 
170 	xdev = devm_kzalloc(dev, sizeof(*xdev), GFP_KERNEL);
171 	if (!xdev)
172 		return -ENOMEM;
173 
174 	xilinx_wdt_wdd = &xdev->xilinx_wdt_wdd;
175 	xilinx_wdt_wdd->info = &xilinx_wdt_ident;
176 	xilinx_wdt_wdd->ops = &xilinx_wdt_ops;
177 	xilinx_wdt_wdd->parent = dev;
178 
179 	xdev->base = devm_platform_ioremap_resource(pdev, 0);
180 	if (IS_ERR(xdev->base))
181 		return PTR_ERR(xdev->base);
182 
183 	rc = of_property_read_u32(dev->of_node, "xlnx,wdt-interval",
184 				  &xdev->wdt_interval);
185 	if (rc)
186 		dev_warn(dev, "Parameter \"xlnx,wdt-interval\" not found\n");
187 
188 	rc = of_property_read_u32(dev->of_node, "xlnx,wdt-enable-once",
189 				  &enable_once);
190 	if (rc)
191 		dev_warn(dev,
192 			 "Parameter \"xlnx,wdt-enable-once\" not found\n");
193 
194 	watchdog_set_nowayout(xilinx_wdt_wdd, enable_once);
195 
196 	xdev->clk = devm_clk_get(dev, NULL);
197 	if (IS_ERR(xdev->clk)) {
198 		if (PTR_ERR(xdev->clk) != -ENOENT)
199 			return PTR_ERR(xdev->clk);
200 
201 		/*
202 		 * Clock framework support is optional, continue on
203 		 * anyways if we don't find a matching clock.
204 		 */
205 		xdev->clk = NULL;
206 
207 		rc = of_property_read_u32(dev->of_node, "clock-frequency",
208 					  &pfreq);
209 		if (rc)
210 			dev_warn(dev,
211 				 "The watchdog clock freq cannot be obtained\n");
212 	} else {
213 		pfreq = clk_get_rate(xdev->clk);
214 		rc = clk_prepare_enable(xdev->clk);
215 		if (rc) {
216 			dev_err(dev, "unable to enable clock\n");
217 			return rc;
218 		}
219 		rc = devm_add_action_or_reset(dev, xwdt_clk_disable_unprepare,
220 					      xdev->clk);
221 		if (rc)
222 			return rc;
223 	}
224 
225 	/*
226 	 * Twice of the 2^wdt_interval / freq  because the first wdt overflow is
227 	 * ignored (interrupt), reset is only generated at second wdt overflow
228 	 */
229 	if (pfreq && xdev->wdt_interval)
230 		xilinx_wdt_wdd->timeout = 2 * ((1 << xdev->wdt_interval) /
231 					  pfreq);
232 
233 	spin_lock_init(&xdev->spinlock);
234 	watchdog_set_drvdata(xilinx_wdt_wdd, xdev);
235 
236 	rc = xwdt_selftest(xdev);
237 	if (rc == XWT_TIMER_FAILED) {
238 		dev_err(dev, "SelfTest routine error\n");
239 		return rc;
240 	}
241 
242 	rc = devm_watchdog_register_device(dev, xilinx_wdt_wdd);
243 	if (rc)
244 		return rc;
245 
246 	clk_disable(xdev->clk);
247 
248 	dev_info(dev, "Xilinx Watchdog Timer with timeout %ds\n",
249 		 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