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/bitops.h>
13 #include <linux/device.h>
14 #include <linux/errno.h>
15 #include <linux/interrupt.h>
16 #include <linux/math.h>
17 #include <linux/module.h>
18 #include <linux/panic.h>
19 #include <linux/platform_device.h>
20 #include <linux/types.h>
21 #include <linux/watchdog.h>
22
23 #include <linux/platform_data/x86/intel-mid_wdt.h>
24 #include <linux/platform_data/x86/intel_scu_ipc.h>
25
26 #define IPC_WATCHDOG 0xf8
27
28 #define MID_WDT_PRETIMEOUT 15
29 #define MID_WDT_TIMEOUT_MIN (1 + MID_WDT_PRETIMEOUT)
30 #define MID_WDT_TIMEOUT_MAX 170
31 #define MID_WDT_DEFAULT_TIMEOUT 90
32
33 /* SCU watchdog messages */
34 enum {
35 SCU_WATCHDOG_START = 0,
36 SCU_WATCHDOG_STOP,
37 SCU_WATCHDOG_KEEPALIVE,
38 };
39
40 struct mid_wdt {
41 struct watchdog_device wd;
42 struct device *dev;
43 struct intel_scu_ipc_dev *scu;
44 };
45
46 static inline int
wdt_command(struct mid_wdt * mid,int sub,const void * in,size_t inlen,size_t size)47 wdt_command(struct mid_wdt *mid, int sub, const void *in, size_t inlen, size_t size)
48 {
49 struct intel_scu_ipc_dev *scu = mid->scu;
50
51 return intel_scu_ipc_dev_command_with_size(scu, IPC_WATCHDOG, sub, in,
52 inlen, size, NULL, 0);
53 }
54
wdt_start(struct watchdog_device * wd)55 static int wdt_start(struct watchdog_device *wd)
56 {
57 struct mid_wdt *mid = watchdog_get_drvdata(wd);
58 int ret, in_size;
59 int timeout = wd->timeout;
60 struct ipc_wd_start {
61 u32 pretimeout;
62 u32 timeout;
63 } ipc_wd_start = { timeout - MID_WDT_PRETIMEOUT, timeout };
64
65 /*
66 * SCU expects the input size for watchdog IPC to be 2 which is the
67 * size of the structure in dwords. SCU IPC normally takes bytes
68 * but this is a special case where we specify size to be different
69 * than inlen.
70 */
71 in_size = DIV_ROUND_UP(sizeof(ipc_wd_start), 4);
72
73 ret = wdt_command(mid, SCU_WATCHDOG_START, &ipc_wd_start,
74 sizeof(ipc_wd_start), in_size);
75 if (ret)
76 dev_crit(mid->dev, "error starting watchdog: %d\n", ret);
77
78 return ret;
79 }
80
wdt_ping(struct watchdog_device * wd)81 static int wdt_ping(struct watchdog_device *wd)
82 {
83 struct mid_wdt *mid = watchdog_get_drvdata(wd);
84 int ret;
85
86 ret = wdt_command(mid, SCU_WATCHDOG_KEEPALIVE, NULL, 0, 0);
87 if (ret)
88 dev_crit(mid->dev, "Error executing keepalive: %d\n", ret);
89
90 return ret;
91 }
92
wdt_stop(struct watchdog_device * wd)93 static int wdt_stop(struct watchdog_device *wd)
94 {
95 struct mid_wdt *mid = watchdog_get_drvdata(wd);
96 int ret;
97
98 ret = wdt_command(mid, SCU_WATCHDOG_STOP, NULL, 0, 0);
99 if (ret)
100 dev_crit(mid->dev, "Error stopping watchdog: %d\n", ret);
101
102 return ret;
103 }
104
mid_wdt_irq(int irq,void * dev_id)105 static irqreturn_t mid_wdt_irq(int irq, void *dev_id)
106 {
107 panic("Kernel Watchdog");
108
109 /* This code should not be reached */
110 return IRQ_HANDLED;
111 }
112
113 static const struct watchdog_info mid_wdt_info = {
114 .identity = "Intel MID SCU watchdog",
115 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
116 };
117
118 static const struct watchdog_ops mid_wdt_ops = {
119 .owner = THIS_MODULE,
120 .start = wdt_start,
121 .stop = wdt_stop,
122 .ping = wdt_ping,
123 };
124
mid_wdt_probe(struct platform_device * pdev)125 static int mid_wdt_probe(struct platform_device *pdev)
126 {
127 struct device *dev = &pdev->dev;
128 struct watchdog_device *wdt_dev;
129 struct intel_mid_wdt_pdata *pdata = dev_get_platdata(dev);
130 struct mid_wdt *mid;
131 int ret;
132
133 if (!pdata) {
134 dev_err(dev, "missing platform data\n");
135 return -EINVAL;
136 }
137
138 if (pdata->probe) {
139 ret = pdata->probe(pdev);
140 if (ret)
141 return ret;
142 }
143
144 mid = devm_kzalloc(dev, sizeof(*mid), GFP_KERNEL);
145 if (!mid)
146 return -ENOMEM;
147
148 mid->dev = dev;
149 wdt_dev = &mid->wd;
150
151 wdt_dev->info = &mid_wdt_info;
152 wdt_dev->ops = &mid_wdt_ops;
153 wdt_dev->min_timeout = MID_WDT_TIMEOUT_MIN;
154 wdt_dev->max_timeout = MID_WDT_TIMEOUT_MAX;
155 wdt_dev->timeout = MID_WDT_DEFAULT_TIMEOUT;
156 wdt_dev->parent = dev;
157
158 watchdog_set_nowayout(wdt_dev, WATCHDOG_NOWAYOUT);
159 watchdog_set_drvdata(wdt_dev, mid);
160
161 mid->scu = devm_intel_scu_ipc_dev_get(dev);
162 if (!mid->scu)
163 return -EPROBE_DEFER;
164
165 ret = devm_request_irq(dev, pdata->irq, mid_wdt_irq,
166 IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog",
167 wdt_dev);
168 if (ret) {
169 dev_err(dev, "error requesting warning irq %d\n", pdata->irq);
170 return ret;
171 }
172
173 /*
174 * The firmware followed by U-Boot leaves the watchdog running
175 * with the default threshold which may vary. When we get here
176 * we should make a decision to prevent any side effects before
177 * user space daemon will take care of it. The best option,
178 * taking into consideration that there is no way to read values
179 * back from hardware, is to enforce watchdog being run with
180 * deterministic values.
181 */
182 ret = wdt_start(wdt_dev);
183 if (ret)
184 return ret;
185
186 /* Make sure the watchdog is serviced */
187 set_bit(WDOG_HW_RUNNING, &wdt_dev->status);
188
189 ret = devm_watchdog_register_device(dev, wdt_dev);
190 if (ret)
191 return ret;
192
193 dev_info(dev, "Intel MID watchdog device probed\n");
194
195 return 0;
196 }
197
198 static struct platform_driver mid_wdt_driver = {
199 .probe = mid_wdt_probe,
200 .driver = {
201 .name = "intel_mid_wdt",
202 },
203 };
204
205 module_platform_driver(mid_wdt_driver);
206
207 MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
208 MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform");
209 MODULE_LICENSE("GPL");
210 MODULE_ALIAS("platform:intel_mid_wdt");
211