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
23enum 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
31static bool nowayout = WATCHDOG_NOWAYOUT;
32static unsigned int timeout;
33
34static 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
56static int smcwd_ping(struct watchdog_device *wdd)
57{
58 return smcwd_call(wdd, call: SMCWD_PET, arg: 0, NULL);
59}
60
61static unsigned int smcwd_get_timeleft(struct watchdog_device *wdd)
62{
63 struct arm_smccc_res res;
64
65 smcwd_call(wdd, call: SMCWD_GET_TIMELEFT, arg: 0, res: &res);
66 if (res.a0)
67 return 0;
68 return res.a1;
69}
70
71static int smcwd_set_timeout(struct watchdog_device *wdd, unsigned int timeout)
72{
73 int res;
74
75 res = smcwd_call(wdd, call: SMCWD_SET_TIMEOUT, arg: timeout, NULL);
76 if (!res)
77 wdd->timeout = timeout;
78 return res;
79}
80
81static int smcwd_stop(struct watchdog_device *wdd)
82{
83 return smcwd_call(wdd, call: SMCWD_ENABLE, arg: 0, NULL);
84}
85
86static int smcwd_start(struct watchdog_device *wdd)
87{
88 return smcwd_call(wdd, call: SMCWD_ENABLE, arg: 1, NULL);
89}
90
91static const struct watchdog_info smcwd_info = {
92 .identity = DRV_NAME,
93 .options = WDIOF_SETTIMEOUT |
94 WDIOF_KEEPALIVEPING |
95 WDIOF_MAGICCLOSE,
96};
97
98static 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
105static 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
113static 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(dev: &pdev->dev, size: sizeof(*wdd), GFP_KERNEL);
121 if (!wdd)
122 return -ENOMEM;
123 platform_set_drvdata(pdev, data: wdd);
124
125 if (of_property_read_u32(np: pdev->dev.of_node, propname: "arm,smc-id",
126 out_value: &smc_func_id))
127 smc_func_id = 0x82003D06;
128 watchdog_set_drvdata(wdd, data: (void *)(uintptr_t)smc_func_id);
129
130 err = smcwd_call(wdd, call: SMCWD_INIT, arg: 0, res: &res);
131 if (err < 0)
132 return err;
133
134 wdd->info = &smcwd_info;
135 /* get_timeleft is optional */
136 err = smcwd_call(wdd, call: SMCWD_GET_TIMELEFT, arg: 0, NULL);
137 switch (err) {
138 case 0:
139 set_bit(WDOG_HW_RUNNING, addr: &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_parm: timeout, dev: &pdev->dev);
158 err = smcwd_set_timeout(wdd, timeout: wdd->timeout);
159 if (err)
160 return err;
161
162 err = devm_watchdog_register_device(dev: &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
173static const struct of_device_id smcwd_dt_ids[] = {
174 { .compatible = "arm,smc-wdt" },
175 {}
176};
177MODULE_DEVICE_TABLE(of, smcwd_dt_ids);
178
179static 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
187module_platform_driver(smcwd_driver);
188
189module_param(timeout, uint, 0);
190MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
191
192module_param(nowayout, bool, 0);
193MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
194 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
195
196MODULE_LICENSE("GPL");
197MODULE_AUTHOR("Julius Werner <jwerner@chromium.org>");
198MODULE_DESCRIPTION("ARM Secure Monitor Call Watchdog Driver");
199MODULE_VERSION(DRV_VERSION);
200

source code of linux/drivers/watchdog/arm_smc_wdt.c