1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * ARM Secure Monitor Call watchdog driver
4 *
5 * Copyright 2020 Google LLC.
6 * Julius Werner <jwerner@chromium.org>
7 * Based on mtk_wdt.c
8 */
9
10 #include <linux/arm-smccc.h>
11 #include <linux/err.h>
12 #include <linux/module.h>
13 #include <linux/moduleparam.h>
14 #include <linux/of.h>
15 #include <linux/platform_device.h>
16 #include <linux/types.h>
17 #include <linux/watchdog.h>
18 #include <uapi/linux/psci.h>
19
20 #define DRV_NAME "arm_smc_wdt"
21 #define DRV_VERSION "1.0"
22
23 enum smcwd_call {
24 SMCWD_INIT = 0,
25 SMCWD_SET_TIMEOUT = 1,
26 SMCWD_ENABLE = 2,
27 SMCWD_PET = 3,
28 SMCWD_GET_TIMELEFT = 4,
29 };
30
31 static bool nowayout = WATCHDOG_NOWAYOUT;
32 static unsigned int timeout;
33
smcwd_call(struct watchdog_device * wdd,enum smcwd_call call,unsigned long arg,struct arm_smccc_res * res)34 static int smcwd_call(struct watchdog_device *wdd, enum smcwd_call call,
35 unsigned long arg, struct arm_smccc_res *res)
36 {
37 struct arm_smccc_res local_res;
38
39 if (!res)
40 res = &local_res;
41
42 arm_smccc_smc((u32)(uintptr_t)watchdog_get_drvdata(wdd), call, arg, 0,
43 0, 0, 0, 0, res);
44
45 if (res->a0 == PSCI_RET_NOT_SUPPORTED)
46 return -ENODEV;
47 if (res->a0 == PSCI_RET_INVALID_PARAMS)
48 return -EINVAL;
49 if (res->a0 != PSCI_RET_SUCCESS)
50 return -EIO;
51 return 0;
52 }
53
smcwd_ping(struct watchdog_device * wdd)54 static int smcwd_ping(struct watchdog_device *wdd)
55 {
56 return smcwd_call(wdd, SMCWD_PET, 0, NULL);
57 }
58
smcwd_get_timeleft(struct watchdog_device * wdd)59 static unsigned int smcwd_get_timeleft(struct watchdog_device *wdd)
60 {
61 struct arm_smccc_res res;
62
63 smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, &res);
64 if (res.a0)
65 return 0;
66 return res.a1;
67 }
68
smcwd_set_timeout(struct watchdog_device * wdd,unsigned int timeout)69 static int smcwd_set_timeout(struct watchdog_device *wdd, unsigned int timeout)
70 {
71 int res;
72
73 res = smcwd_call(wdd, SMCWD_SET_TIMEOUT, timeout, NULL);
74 if (!res)
75 wdd->timeout = timeout;
76 return res;
77 }
78
smcwd_stop(struct watchdog_device * wdd)79 static int smcwd_stop(struct watchdog_device *wdd)
80 {
81 return smcwd_call(wdd, SMCWD_ENABLE, 0, NULL);
82 }
83
smcwd_start(struct watchdog_device * wdd)84 static int smcwd_start(struct watchdog_device *wdd)
85 {
86 return smcwd_call(wdd, SMCWD_ENABLE, 1, NULL);
87 }
88
89 static const struct watchdog_info smcwd_info = {
90 .identity = DRV_NAME,
91 .options = WDIOF_SETTIMEOUT |
92 WDIOF_KEEPALIVEPING |
93 WDIOF_MAGICCLOSE,
94 };
95
96 static const struct watchdog_ops smcwd_ops = {
97 .start = smcwd_start,
98 .stop = smcwd_stop,
99 .ping = smcwd_ping,
100 .set_timeout = smcwd_set_timeout,
101 };
102
103 static const struct watchdog_ops smcwd_timeleft_ops = {
104 .start = smcwd_start,
105 .stop = smcwd_stop,
106 .ping = smcwd_ping,
107 .set_timeout = smcwd_set_timeout,
108 .get_timeleft = smcwd_get_timeleft,
109 };
110
smcwd_probe(struct platform_device * pdev)111 static int smcwd_probe(struct platform_device *pdev)
112 {
113 struct watchdog_device *wdd;
114 int err;
115 struct arm_smccc_res res;
116 u32 smc_func_id;
117
118 wdd = devm_kzalloc(&pdev->dev, sizeof(*wdd), GFP_KERNEL);
119 if (!wdd)
120 return -ENOMEM;
121 platform_set_drvdata(pdev, wdd);
122
123 if (of_property_read_u32(pdev->dev.of_node, "arm,smc-id",
124 &smc_func_id))
125 smc_func_id = 0x82003D06;
126 watchdog_set_drvdata(wdd, (void *)(uintptr_t)smc_func_id);
127
128 err = smcwd_call(wdd, SMCWD_INIT, 0, &res);
129 if (err < 0)
130 return err;
131
132 wdd->info = &smcwd_info;
133 /* get_timeleft is optional */
134 if (smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, NULL))
135 wdd->ops = &smcwd_ops;
136 else
137 wdd->ops = &smcwd_timeleft_ops;
138 wdd->timeout = res.a2;
139 wdd->max_timeout = res.a2;
140 wdd->min_timeout = res.a1;
141 wdd->parent = &pdev->dev;
142
143 watchdog_stop_on_reboot(wdd);
144 watchdog_stop_on_unregister(wdd);
145 watchdog_set_nowayout(wdd, nowayout);
146 watchdog_init_timeout(wdd, timeout, &pdev->dev);
147 err = smcwd_set_timeout(wdd, wdd->timeout);
148 if (err)
149 return err;
150
151 err = devm_watchdog_register_device(&pdev->dev, wdd);
152 if (err)
153 return err;
154
155 dev_info(&pdev->dev,
156 "Watchdog registered (timeout=%d sec, nowayout=%d)\n",
157 wdd->timeout, nowayout);
158
159 return 0;
160 }
161
162 static const struct of_device_id smcwd_dt_ids[] = {
163 { .compatible = "arm,smc-wdt" },
164 {}
165 };
166 MODULE_DEVICE_TABLE(of, smcwd_dt_ids);
167
168 static struct platform_driver smcwd_driver = {
169 .probe = smcwd_probe,
170 .driver = {
171 .name = DRV_NAME,
172 .of_match_table = smcwd_dt_ids,
173 },
174 };
175
176 module_platform_driver(smcwd_driver);
177
178 module_param(timeout, uint, 0);
179 MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
180
181 module_param(nowayout, bool, 0);
182 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
183 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
184
185 MODULE_LICENSE("GPL");
186 MODULE_AUTHOR("Julius Werner <jwerner@chromium.org>");
187 MODULE_DESCRIPTION("ARM Secure Monitor Call Watchdog Driver");
188 MODULE_VERSION(DRV_VERSION);
189