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_DISABLED)
50 return -ENODATA;
51 if (res->a0 != PSCI_RET_SUCCESS)
52 return -EIO;
53 return 0;
54 }
55
smcwd_ping(struct watchdog_device * wdd)56 static int smcwd_ping(struct watchdog_device *wdd)
57 {
58 return smcwd_call(wdd, SMCWD_PET, 0, NULL);
59 }
60
smcwd_get_timeleft(struct watchdog_device * wdd)61 static unsigned int smcwd_get_timeleft(struct watchdog_device *wdd)
62 {
63 struct arm_smccc_res res;
64
65 smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, &res);
66 if (res.a0)
67 return 0;
68 return res.a1;
69 }
70
smcwd_set_timeout(struct watchdog_device * wdd,unsigned int timeout)71 static int smcwd_set_timeout(struct watchdog_device *wdd, unsigned int timeout)
72 {
73 int res;
74
75 res = smcwd_call(wdd, SMCWD_SET_TIMEOUT, timeout, NULL);
76 if (!res)
77 wdd->timeout = timeout;
78 return res;
79 }
80
smcwd_stop(struct watchdog_device * wdd)81 static int smcwd_stop(struct watchdog_device *wdd)
82 {
83 return smcwd_call(wdd, SMCWD_ENABLE, 0, NULL);
84 }
85
smcwd_start(struct watchdog_device * wdd)86 static int smcwd_start(struct watchdog_device *wdd)
87 {
88 return smcwd_call(wdd, SMCWD_ENABLE, 1, NULL);
89 }
90
91 static const struct watchdog_info smcwd_info = {
92 .identity = DRV_NAME,
93 .options = WDIOF_SETTIMEOUT |
94 WDIOF_KEEPALIVEPING |
95 WDIOF_MAGICCLOSE,
96 };
97
98 static const struct watchdog_ops smcwd_ops = {
99 .start = smcwd_start,
100 .stop = smcwd_stop,
101 .ping = smcwd_ping,
102 .set_timeout = smcwd_set_timeout,
103 };
104
105 static const struct watchdog_ops smcwd_timeleft_ops = {
106 .start = smcwd_start,
107 .stop = smcwd_stop,
108 .ping = smcwd_ping,
109 .set_timeout = smcwd_set_timeout,
110 .get_timeleft = smcwd_get_timeleft,
111 };
112
smcwd_probe(struct platform_device * pdev)113 static int smcwd_probe(struct platform_device *pdev)
114 {
115 struct watchdog_device *wdd;
116 int err;
117 struct arm_smccc_res res;
118 u32 smc_func_id;
119
120 wdd = devm_kzalloc(&pdev->dev, sizeof(*wdd), GFP_KERNEL);
121 if (!wdd)
122 return -ENOMEM;
123 platform_set_drvdata(pdev, wdd);
124
125 if (of_property_read_u32(pdev->dev.of_node, "arm,smc-id",
126 &smc_func_id))
127 smc_func_id = 0x82003D06;
128 watchdog_set_drvdata(wdd, (void *)(uintptr_t)smc_func_id);
129
130 err = smcwd_call(wdd, SMCWD_INIT, 0, &res);
131 if (err < 0)
132 return err;
133
134 wdd->info = &smcwd_info;
135 /* get_timeleft is optional */
136 err = smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, NULL);
137 switch (err) {
138 case 0:
139 set_bit(WDOG_HW_RUNNING, &wdd->status);
140 fallthrough;
141 case -ENODATA:
142 wdd->ops = &smcwd_timeleft_ops;
143 break;
144 default:
145 wdd->ops = &smcwd_ops;
146 break;
147 }
148
149 wdd->timeout = res.a2;
150 wdd->max_timeout = res.a2;
151 wdd->min_timeout = res.a1;
152 wdd->parent = &pdev->dev;
153
154 watchdog_stop_on_reboot(wdd);
155 watchdog_stop_on_unregister(wdd);
156 watchdog_set_nowayout(wdd, nowayout);
157 watchdog_init_timeout(wdd, timeout, &pdev->dev);
158 err = smcwd_set_timeout(wdd, wdd->timeout);
159 if (err)
160 return err;
161
162 err = devm_watchdog_register_device(&pdev->dev, wdd);
163 if (err)
164 return err;
165
166 dev_info(&pdev->dev,
167 "Watchdog registered (timeout=%d sec, nowayout=%d)\n",
168 wdd->timeout, nowayout);
169
170 return 0;
171 }
172
173 static const struct of_device_id smcwd_dt_ids[] = {
174 { .compatible = "arm,smc-wdt" },
175 {}
176 };
177 MODULE_DEVICE_TABLE(of, smcwd_dt_ids);
178
179 static struct platform_driver smcwd_driver = {
180 .probe = smcwd_probe,
181 .driver = {
182 .name = DRV_NAME,
183 .of_match_table = smcwd_dt_ids,
184 },
185 };
186
187 module_platform_driver(smcwd_driver);
188
189 module_param(timeout, uint, 0);
190 MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
191
192 module_param(nowayout, bool, 0);
193 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
194 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
195
196 MODULE_LICENSE("GPL");
197 MODULE_AUTHOR("Julius Werner <jwerner@chromium.org>");
198 MODULE_DESCRIPTION("ARM Secure Monitor Call Watchdog Driver");
199 MODULE_VERSION(DRV_VERSION);
200