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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 | ||
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 | ||
54 | static int smcwd_ping(struct watchdog_device *wdd) | |
55 | { | |
56 | return smcwd_call(wdd, SMCWD_PET, 0, NULL); | |
57 | } | |
58 | ||
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 | ||
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 | ||
79 | static int smcwd_stop(struct watchdog_device *wdd) | |
80 | { | |
81 | return smcwd_call(wdd, SMCWD_ENABLE, 0, NULL); | |
82 | } | |
83 | ||
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 | ||
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); |