1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * ARM Secure Monitor Call watchdog driver
4 * Copyright (C) 2022, STMicroelectronics - All Rights Reserved
5 * This file is based on Linux driver drivers/watchdog/arm_smc_wdt.c
6 */
7
8#define LOG_CATEGORY UCLASS_WDT
9
10#include <dm.h>
11#include <dm/device_compat.h>
12#include <linux/arm-smccc.h>
13#include <linux/psci.h>
14#include <wdt.h>
15
16#define DRV_NAME		"arm_smc_wdt"
17
18#define WDT_TIMEOUT_SECS(TIMEOUT)	((TIMEOUT) / 1000)
19
20enum smcwd_call {
21	SMCWD_INIT		= 0,
22	SMCWD_SET_TIMEOUT	= 1,
23	SMCWD_ENABLE		= 2,
24	SMCWD_PET		= 3,
25	SMCWD_GET_TIMELEFT	= 4,
26};
27
28struct smcwd_priv_data {
29	u32 smc_id;
30	unsigned int min_timeout;
31	unsigned int max_timeout;
32};
33
34static int smcwd_call(struct udevice *dev, enum smcwd_call call,
35		      unsigned long arg, struct arm_smccc_res *res)
36{
37	struct smcwd_priv_data *priv = dev_get_priv(dev);
38	struct arm_smccc_res local_res;
39
40	if (!res)
41		res = &local_res;
42
43	arm_smccc_smc(priv->smc_id, call, arg, 0, 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
52	return 0;
53}
54
55static int smcwd_reset(struct udevice *dev)
56{
57	return smcwd_call(dev, SMCWD_PET, 0, NULL);
58}
59
60static int smcwd_stop(struct udevice *dev)
61{
62	return smcwd_call(dev, SMCWD_ENABLE, 0, NULL);
63}
64
65static int smcwd_start(struct udevice *dev, u64 timeout_ms, ulong flags)
66{
67	struct smcwd_priv_data *priv = dev_get_priv(dev);
68	u64 timeout_sec = WDT_TIMEOUT_SECS(timeout_ms);
69	int err;
70
71	if (timeout_sec < priv->min_timeout || timeout_sec > priv->max_timeout)	{
72		dev_err(dev, "Timeout value not supported\n");
73		return -EINVAL;
74	}
75
76	err = smcwd_call(dev, SMCWD_SET_TIMEOUT, timeout_sec, NULL);
77	if (err) {
78		dev_err(dev, "Timeout out configuration failed\n");
79		return err;
80	}
81
82	return smcwd_call(dev, SMCWD_ENABLE, 1, NULL);
83}
84
85static int smcwd_probe(struct udevice *dev)
86{
87	struct smcwd_priv_data *priv = dev_get_priv(dev);
88	struct arm_smccc_res res;
89	int err;
90
91	priv->smc_id = dev_read_u32_default(dev, "arm,smc-id", 0x82003D06);
92
93	err = smcwd_call(dev, SMCWD_INIT, 0, &res);
94	if (err < 0) {
95		dev_err(dev, "Init failed %i\n", err);
96		return err;
97	}
98
99	priv->min_timeout = res.a1;
100	priv->max_timeout = res.a2;
101
102	return 0;
103}
104
105static const struct wdt_ops smcwd_ops = {
106	.start		= smcwd_start,
107	.stop		= smcwd_stop,
108	.reset		= smcwd_reset,
109};
110
111static const struct udevice_id smcwd_dt_ids[] = {
112	{ .compatible = "arm,smc-wdt" },
113	{}
114};
115
116U_BOOT_DRIVER(wdt_sandbox) = {
117	.name = "smcwd",
118	.id = UCLASS_WDT,
119	.of_match = smcwd_dt_ids,
120	.priv_auto = sizeof(struct smcwd_priv_data),
121	.probe = smcwd_probe,
122	.ops = &smcwd_ops,
123};
124