1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Window watchdog device driver for Xilinx Versal WWDT
4  *
5  * Copyright (C) 2022 - 2023, Advanced Micro Devices, Inc.
6  */
7 
8 #include <linux/clk.h>
9 #include <linux/interrupt.h>
10 #include <linux/io.h>
11 #include <linux/ioport.h>
12 #include <linux/math64.h>
13 #include <linux/mod_devicetable.h>
14 #include <linux/module.h>
15 #include <linux/platform_device.h>
16 #include <linux/watchdog.h>
17 
18 /* Max timeout is calculated at 100MHz source clock */
19 #define XWWDT_DEFAULT_TIMEOUT	42
20 #define XWWDT_MIN_TIMEOUT	1
21 
22 /* Register offsets for the WWDT device */
23 #define XWWDT_MWR_OFFSET	0x00
24 #define XWWDT_ESR_OFFSET	0x04
25 #define XWWDT_FCR_OFFSET	0x08
26 #define XWWDT_FWR_OFFSET	0x0c
27 #define XWWDT_SWR_OFFSET	0x10
28 
29 /* Master Write Control Register Masks */
30 #define XWWDT_MWR_MASK		BIT(0)
31 
32 /* Enable and Status Register Masks */
33 #define XWWDT_ESR_WINT_MASK	BIT(16)
34 #define XWWDT_ESR_WSW_MASK	BIT(8)
35 #define XWWDT_ESR_WEN_MASK	BIT(0)
36 
37 #define XWWDT_CLOSE_WINDOW_PERCENT	50
38 
39 static int wwdt_timeout;
40 static int closed_window_percent;
41 
42 module_param(wwdt_timeout, int, 0);
43 MODULE_PARM_DESC(wwdt_timeout,
44 		 "Watchdog time in seconds. (default="
45 		 __MODULE_STRING(XWWDT_DEFAULT_TIMEOUT) ")");
46 module_param(closed_window_percent, int, 0);
47 MODULE_PARM_DESC(closed_window_percent,
48 		 "Watchdog closed window percentage. (default="
49 		 __MODULE_STRING(XWWDT_CLOSE_WINDOW_PERCENT) ")");
50 /**
51  * struct xwwdt_device - Watchdog device structure
52  * @base: base io address of WDT device
53  * @spinlock: spinlock for IO register access
54  * @xilinx_wwdt_wdd: watchdog device structure
55  * @freq: source clock frequency of WWDT
56  * @close_percent: Closed window percent
57  */
58 struct xwwdt_device {
59 	void __iomem *base;
60 	spinlock_t spinlock; /* spinlock for register handling */
61 	struct watchdog_device xilinx_wwdt_wdd;
62 	unsigned long freq;
63 	u32 close_percent;
64 };
65 
xilinx_wwdt_start(struct watchdog_device * wdd)66 static int xilinx_wwdt_start(struct watchdog_device *wdd)
67 {
68 	struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
69 	struct watchdog_device *xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
70 	u64 time_out, closed_timeout, open_timeout;
71 	u32 control_status_reg;
72 
73 	/* Calculate timeout count */
74 	time_out = xdev->freq * wdd->timeout;
75 	closed_timeout = div_u64(time_out * xdev->close_percent, 100);
76 	open_timeout = time_out - closed_timeout;
77 	wdd->min_hw_heartbeat_ms = xdev->close_percent * 10 * wdd->timeout;
78 
79 	spin_lock(&xdev->spinlock);
80 
81 	iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
82 	iowrite32(~(u32)XWWDT_ESR_WEN_MASK, xdev->base + XWWDT_ESR_OFFSET);
83 	iowrite32((u32)closed_timeout, xdev->base + XWWDT_FWR_OFFSET);
84 	iowrite32((u32)open_timeout, xdev->base + XWWDT_SWR_OFFSET);
85 
86 	/* Enable the window watchdog timer */
87 	control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
88 	control_status_reg |= XWWDT_ESR_WEN_MASK;
89 	iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
90 
91 	spin_unlock(&xdev->spinlock);
92 
93 	dev_dbg(xilinx_wwdt_wdd->parent, "Watchdog Started!\n");
94 
95 	return 0;
96 }
97 
xilinx_wwdt_keepalive(struct watchdog_device * wdd)98 static int xilinx_wwdt_keepalive(struct watchdog_device *wdd)
99 {
100 	struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
101 	u32 control_status_reg;
102 
103 	spin_lock(&xdev->spinlock);
104 
105 	/* Enable write access control bit for the window watchdog */
106 	iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
107 
108 	/* Trigger restart kick to watchdog */
109 	control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
110 	control_status_reg |= XWWDT_ESR_WSW_MASK;
111 	iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
112 
113 	spin_unlock(&xdev->spinlock);
114 
115 	return 0;
116 }
117 
118 static const struct watchdog_info xilinx_wwdt_ident = {
119 	.options = WDIOF_KEEPALIVEPING |
120 		WDIOF_SETTIMEOUT,
121 	.firmware_version = 1,
122 	.identity = "xlnx_window watchdog",
123 };
124 
125 static const struct watchdog_ops xilinx_wwdt_ops = {
126 	.owner = THIS_MODULE,
127 	.start = xilinx_wwdt_start,
128 	.ping = xilinx_wwdt_keepalive,
129 };
130 
xwwdt_probe(struct platform_device * pdev)131 static int xwwdt_probe(struct platform_device *pdev)
132 {
133 	struct watchdog_device *xilinx_wwdt_wdd;
134 	struct device *dev = &pdev->dev;
135 	struct xwwdt_device *xdev;
136 	struct clk *clk;
137 	int ret;
138 
139 	xdev = devm_kzalloc(dev, sizeof(*xdev), GFP_KERNEL);
140 	if (!xdev)
141 		return -ENOMEM;
142 
143 	xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
144 	xilinx_wwdt_wdd->info = &xilinx_wwdt_ident;
145 	xilinx_wwdt_wdd->ops = &xilinx_wwdt_ops;
146 	xilinx_wwdt_wdd->parent = dev;
147 
148 	xdev->base = devm_platform_ioremap_resource(pdev, 0);
149 	if (IS_ERR(xdev->base))
150 		return PTR_ERR(xdev->base);
151 
152 	clk = devm_clk_get_enabled(dev, NULL);
153 	if (IS_ERR(clk))
154 		return PTR_ERR(clk);
155 
156 	xdev->freq = clk_get_rate(clk);
157 	if (!xdev->freq)
158 		return -EINVAL;
159 
160 	xilinx_wwdt_wdd->min_timeout = XWWDT_MIN_TIMEOUT;
161 	xilinx_wwdt_wdd->timeout = XWWDT_DEFAULT_TIMEOUT;
162 	xilinx_wwdt_wdd->max_hw_heartbeat_ms = 1000 * xilinx_wwdt_wdd->timeout;
163 
164 	if (closed_window_percent == 0 || closed_window_percent >= 100)
165 		xdev->close_percent = XWWDT_CLOSE_WINDOW_PERCENT;
166 	else
167 		xdev->close_percent = closed_window_percent;
168 
169 	watchdog_init_timeout(xilinx_wwdt_wdd, wwdt_timeout, &pdev->dev);
170 	spin_lock_init(&xdev->spinlock);
171 	watchdog_set_drvdata(xilinx_wwdt_wdd, xdev);
172 	watchdog_set_nowayout(xilinx_wwdt_wdd, 1);
173 
174 	ret = devm_watchdog_register_device(dev, xilinx_wwdt_wdd);
175 	if (ret)
176 		return ret;
177 
178 	dev_info(dev, "Xilinx window watchdog Timer with timeout %ds\n",
179 		 xilinx_wwdt_wdd->timeout);
180 
181 	return 0;
182 }
183 
184 static const struct of_device_id xwwdt_of_match[] = {
185 	{ .compatible = "xlnx,versal-wwdt", },
186 	{},
187 };
188 MODULE_DEVICE_TABLE(of, xwwdt_of_match);
189 
190 static struct platform_driver xwwdt_driver = {
191 	.probe = xwwdt_probe,
192 	.driver = {
193 		.name = "Xilinx window watchdog",
194 		.of_match_table = xwwdt_of_match,
195 	},
196 };
197 
198 module_platform_driver(xwwdt_driver);
199 
200 MODULE_AUTHOR("Neeli Srinivas <srinivas.neeli@amd.com>");
201 MODULE_DESCRIPTION("Xilinx window watchdog driver");
202 MODULE_LICENSE("GPL");
203