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 
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 
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 
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 
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 
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  */
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  */
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