1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *      intel-mid_wdt: generic Intel MID SCU watchdog driver
4  *
5  *      Platforms supported so far:
6  *      - Merrifield only
7  *
8  *      Copyright (C) 2014 Intel Corporation. All rights reserved.
9  *      Contact: David Cohen <david.a.cohen@linux.intel.com>
10  */
11 
12 #include <linux/interrupt.h>
13 #include <linux/module.h>
14 #include <linux/nmi.h>
15 #include <linux/platform_device.h>
16 #include <linux/watchdog.h>
17 #include <linux/platform_data/intel-mid_wdt.h>
18 
19 #include <asm/intel_scu_ipc.h>
20 #include <asm/intel-mid.h>
21 
22 #define IPC_WATCHDOG 0xf8
23 
24 #define MID_WDT_PRETIMEOUT		15
25 #define MID_WDT_TIMEOUT_MIN		(1 + MID_WDT_PRETIMEOUT)
26 #define MID_WDT_TIMEOUT_MAX		170
27 #define MID_WDT_DEFAULT_TIMEOUT		90
28 
29 /* SCU watchdog messages */
30 enum {
31 	SCU_WATCHDOG_START = 0,
32 	SCU_WATCHDOG_STOP,
33 	SCU_WATCHDOG_KEEPALIVE,
34 };
35 
36 struct mid_wdt {
37 	struct watchdog_device wd;
38 	struct device *dev;
39 	struct intel_scu_ipc_dev *scu;
40 };
41 
42 static inline int
43 wdt_command(struct mid_wdt *mid, int sub, const void *in, size_t inlen, size_t size)
44 {
45 	struct intel_scu_ipc_dev *scu = mid->scu;
46 
47 	return intel_scu_ipc_dev_command_with_size(scu, IPC_WATCHDOG, sub, in,
48 						   inlen, size, NULL, 0);
49 }
50 
51 static int wdt_start(struct watchdog_device *wd)
52 {
53 	struct mid_wdt *mid = watchdog_get_drvdata(wd);
54 	int ret, in_size;
55 	int timeout = wd->timeout;
56 	struct ipc_wd_start {
57 		u32 pretimeout;
58 		u32 timeout;
59 	} ipc_wd_start = { timeout - MID_WDT_PRETIMEOUT, timeout };
60 
61 	/*
62 	 * SCU expects the input size for watchdog IPC to be 2 which is the
63 	 * size of the structure in dwords. SCU IPC normally takes bytes
64 	 * but this is a special case where we specify size to be different
65 	 * than inlen.
66 	 */
67 	in_size = DIV_ROUND_UP(sizeof(ipc_wd_start), 4);
68 
69 	ret = wdt_command(mid, SCU_WATCHDOG_START, &ipc_wd_start,
70 			  sizeof(ipc_wd_start), in_size);
71 	if (ret)
72 		dev_crit(mid->dev, "error starting watchdog: %d\n", ret);
73 
74 	return ret;
75 }
76 
77 static int wdt_ping(struct watchdog_device *wd)
78 {
79 	struct mid_wdt *mid = watchdog_get_drvdata(wd);
80 	int ret;
81 
82 	ret = wdt_command(mid, SCU_WATCHDOG_KEEPALIVE, NULL, 0, 0);
83 	if (ret)
84 		dev_crit(mid->dev, "Error executing keepalive: %d\n", ret);
85 
86 	return ret;
87 }
88 
89 static int wdt_stop(struct watchdog_device *wd)
90 {
91 	struct mid_wdt *mid = watchdog_get_drvdata(wd);
92 	int ret;
93 
94 	ret = wdt_command(mid, SCU_WATCHDOG_STOP, NULL, 0, 0);
95 	if (ret)
96 		dev_crit(mid->dev, "Error stopping watchdog: %d\n", ret);
97 
98 	return ret;
99 }
100 
101 static irqreturn_t mid_wdt_irq(int irq, void *dev_id)
102 {
103 	panic("Kernel Watchdog");
104 
105 	/* This code should not be reached */
106 	return IRQ_HANDLED;
107 }
108 
109 static const struct watchdog_info mid_wdt_info = {
110 	.identity = "Intel MID SCU watchdog",
111 	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
112 };
113 
114 static const struct watchdog_ops mid_wdt_ops = {
115 	.owner = THIS_MODULE,
116 	.start = wdt_start,
117 	.stop = wdt_stop,
118 	.ping = wdt_ping,
119 };
120 
121 static int mid_wdt_probe(struct platform_device *pdev)
122 {
123 	struct device *dev = &pdev->dev;
124 	struct watchdog_device *wdt_dev;
125 	struct intel_mid_wdt_pdata *pdata = dev->platform_data;
126 	struct mid_wdt *mid;
127 	int ret;
128 
129 	if (!pdata) {
130 		dev_err(dev, "missing platform data\n");
131 		return -EINVAL;
132 	}
133 
134 	if (pdata->probe) {
135 		ret = pdata->probe(pdev);
136 		if (ret)
137 			return ret;
138 	}
139 
140 	mid = devm_kzalloc(dev, sizeof(*mid), GFP_KERNEL);
141 	if (!mid)
142 		return -ENOMEM;
143 
144 	mid->dev = dev;
145 	wdt_dev = &mid->wd;
146 
147 	wdt_dev->info = &mid_wdt_info;
148 	wdt_dev->ops = &mid_wdt_ops;
149 	wdt_dev->min_timeout = MID_WDT_TIMEOUT_MIN;
150 	wdt_dev->max_timeout = MID_WDT_TIMEOUT_MAX;
151 	wdt_dev->timeout = MID_WDT_DEFAULT_TIMEOUT;
152 	wdt_dev->parent = dev;
153 
154 	watchdog_set_nowayout(wdt_dev, WATCHDOG_NOWAYOUT);
155 	watchdog_set_drvdata(wdt_dev, mid);
156 
157 	mid->scu = devm_intel_scu_ipc_dev_get(dev);
158 	if (!mid->scu)
159 		return -EPROBE_DEFER;
160 
161 	ret = devm_request_irq(dev, pdata->irq, mid_wdt_irq,
162 			       IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog",
163 			       wdt_dev);
164 	if (ret) {
165 		dev_err(dev, "error requesting warning irq %d\n", pdata->irq);
166 		return ret;
167 	}
168 
169 	/*
170 	 * The firmware followed by U-Boot leaves the watchdog running
171 	 * with the default threshold which may vary. When we get here
172 	 * we should make a decision to prevent any side effects before
173 	 * user space daemon will take care of it. The best option,
174 	 * taking into consideration that there is no way to read values
175 	 * back from hardware, is to enforce watchdog being run with
176 	 * deterministic values.
177 	 */
178 	ret = wdt_start(wdt_dev);
179 	if (ret)
180 		return ret;
181 
182 	/* Make sure the watchdog is serviced */
183 	set_bit(WDOG_HW_RUNNING, &wdt_dev->status);
184 
185 	ret = devm_watchdog_register_device(dev, wdt_dev);
186 	if (ret)
187 		return ret;
188 
189 	dev_info(dev, "Intel MID watchdog device probed\n");
190 
191 	return 0;
192 }
193 
194 static struct platform_driver mid_wdt_driver = {
195 	.probe		= mid_wdt_probe,
196 	.driver		= {
197 		.name	= "intel_mid_wdt",
198 	},
199 };
200 
201 module_platform_driver(mid_wdt_driver);
202 
203 MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
204 MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform");
205 MODULE_LICENSE("GPL");
206