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
wdt_command(int sub,u32 * in,int inlen)36 static inline int wdt_command(int sub, u32 *in, int inlen)
37 {
38 return intel_scu_ipc_command(IPC_WATCHDOG, sub, in, inlen, NULL, 0);
39 }
40
wdt_start(struct watchdog_device * wd)41 static int wdt_start(struct watchdog_device *wd)
42 {
43 struct device *dev = watchdog_get_drvdata(wd);
44 int ret, in_size;
45 int timeout = wd->timeout;
46 struct ipc_wd_start {
47 u32 pretimeout;
48 u32 timeout;
49 } ipc_wd_start = { timeout - MID_WDT_PRETIMEOUT, timeout };
50
51 /*
52 * SCU expects the input size for watchdog IPC to
53 * be based on 4 bytes
54 */
55 in_size = DIV_ROUND_UP(sizeof(ipc_wd_start), 4);
56
57 ret = wdt_command(SCU_WATCHDOG_START, (u32 *)&ipc_wd_start, in_size);
58 if (ret)
59 dev_crit(dev, "error starting watchdog: %d\n", ret);
60
61 return ret;
62 }
63
wdt_ping(struct watchdog_device * wd)64 static int wdt_ping(struct watchdog_device *wd)
65 {
66 struct device *dev = watchdog_get_drvdata(wd);
67 int ret;
68
69 ret = wdt_command(SCU_WATCHDOG_KEEPALIVE, NULL, 0);
70 if (ret)
71 dev_crit(dev, "Error executing keepalive: %d\n", ret);
72
73 return ret;
74 }
75
wdt_stop(struct watchdog_device * wd)76 static int wdt_stop(struct watchdog_device *wd)
77 {
78 struct device *dev = watchdog_get_drvdata(wd);
79 int ret;
80
81 ret = wdt_command(SCU_WATCHDOG_STOP, NULL, 0);
82 if (ret)
83 dev_crit(dev, "Error stopping watchdog: %d\n", ret);
84
85 return ret;
86 }
87
mid_wdt_irq(int irq,void * dev_id)88 static irqreturn_t mid_wdt_irq(int irq, void *dev_id)
89 {
90 panic("Kernel Watchdog");
91
92 /* This code should not be reached */
93 return IRQ_HANDLED;
94 }
95
96 static const struct watchdog_info mid_wdt_info = {
97 .identity = "Intel MID SCU watchdog",
98 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
99 };
100
101 static const struct watchdog_ops mid_wdt_ops = {
102 .owner = THIS_MODULE,
103 .start = wdt_start,
104 .stop = wdt_stop,
105 .ping = wdt_ping,
106 };
107
mid_wdt_probe(struct platform_device * pdev)108 static int mid_wdt_probe(struct platform_device *pdev)
109 {
110 struct device *dev = &pdev->dev;
111 struct watchdog_device *wdt_dev;
112 struct intel_mid_wdt_pdata *pdata = dev->platform_data;
113 int ret;
114
115 if (!pdata) {
116 dev_err(dev, "missing platform data\n");
117 return -EINVAL;
118 }
119
120 if (pdata->probe) {
121 ret = pdata->probe(pdev);
122 if (ret)
123 return ret;
124 }
125
126 wdt_dev = devm_kzalloc(dev, sizeof(*wdt_dev), GFP_KERNEL);
127 if (!wdt_dev)
128 return -ENOMEM;
129
130 wdt_dev->info = &mid_wdt_info;
131 wdt_dev->ops = &mid_wdt_ops;
132 wdt_dev->min_timeout = MID_WDT_TIMEOUT_MIN;
133 wdt_dev->max_timeout = MID_WDT_TIMEOUT_MAX;
134 wdt_dev->timeout = MID_WDT_DEFAULT_TIMEOUT;
135 wdt_dev->parent = dev;
136
137 watchdog_set_drvdata(wdt_dev, dev);
138
139 ret = devm_request_irq(dev, pdata->irq, mid_wdt_irq,
140 IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog",
141 wdt_dev);
142 if (ret) {
143 dev_err(dev, "error requesting warning irq %d\n", pdata->irq);
144 return ret;
145 }
146
147 /*
148 * The firmware followed by U-Boot leaves the watchdog running
149 * with the default threshold which may vary. When we get here
150 * we should make a decision to prevent any side effects before
151 * user space daemon will take care of it. The best option,
152 * taking into consideration that there is no way to read values
153 * back from hardware, is to enforce watchdog being run with
154 * deterministic values.
155 */
156 ret = wdt_start(wdt_dev);
157 if (ret)
158 return ret;
159
160 /* Make sure the watchdog is serviced */
161 set_bit(WDOG_HW_RUNNING, &wdt_dev->status);
162
163 ret = devm_watchdog_register_device(dev, wdt_dev);
164 if (ret)
165 return ret;
166
167 dev_info(dev, "Intel MID watchdog device probed\n");
168
169 return 0;
170 }
171
172 static struct platform_driver mid_wdt_driver = {
173 .probe = mid_wdt_probe,
174 .driver = {
175 .name = "intel_mid_wdt",
176 },
177 };
178
179 module_platform_driver(mid_wdt_driver);
180
181 MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
182 MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform");
183 MODULE_LICENSE("GPL");
184