1/*
2 *      intel-mid_wdt: generic Intel MID SCU watchdog driver
3 *
4 *      Platforms supported so far:
5 *      - Merrifield only
6 *
7 *      Copyright (C) 2014 Intel Corporation. All rights reserved.
8 *      Contact: David Cohen <david.a.cohen@linux.intel.com>
9 *
10 *      This program is free software; you can redistribute it and/or
11 *      modify it under the terms of version 2 of the GNU General
12 *      Public License as published by the Free Software Foundation.
13 */
14
15#include <linux/interrupt.h>
16#include <linux/module.h>
17#include <linux/nmi.h>
18#include <linux/platform_device.h>
19#include <linux/watchdog.h>
20#include <linux/platform_data/intel-mid_wdt.h>
21
22#include <asm/intel_scu_ipc.h>
23#include <asm/intel-mid.h>
24
25#define IPC_WATCHDOG 0xf8
26
27#define MID_WDT_PRETIMEOUT		15
28#define MID_WDT_TIMEOUT_MIN		(1 + MID_WDT_PRETIMEOUT)
29#define MID_WDT_TIMEOUT_MAX		170
30#define MID_WDT_DEFAULT_TIMEOUT		90
31
32/* SCU watchdog messages */
33enum {
34	SCU_WATCHDOG_START = 0,
35	SCU_WATCHDOG_STOP,
36	SCU_WATCHDOG_KEEPALIVE,
37};
38
39static inline int wdt_command(int sub, u32 *in, int inlen)
40{
41	return intel_scu_ipc_command(IPC_WATCHDOG, sub, in, inlen, NULL, 0);
42}
43
44static int wdt_start(struct watchdog_device *wd)
45{
46	int ret, in_size;
47	int timeout = wd->timeout;
48	struct ipc_wd_start {
49		u32 pretimeout;
50		u32 timeout;
51	} ipc_wd_start = { timeout - MID_WDT_PRETIMEOUT, timeout };
52
53	/*
54	 * SCU expects the input size for watchdog IPC to
55	 * be based on 4 bytes
56	 */
57	in_size = DIV_ROUND_UP(sizeof(ipc_wd_start), 4);
58
59	ret = wdt_command(SCU_WATCHDOG_START, (u32 *)&ipc_wd_start, in_size);
60	if (ret) {
61		struct device *dev = watchdog_get_drvdata(wd);
62		dev_crit(dev, "error starting watchdog: %d\n", ret);
63	}
64
65	return ret;
66}
67
68static int wdt_ping(struct watchdog_device *wd)
69{
70	int ret;
71
72	ret = wdt_command(SCU_WATCHDOG_KEEPALIVE, NULL, 0);
73	if (ret) {
74		struct device *dev = watchdog_get_drvdata(wd);
75		dev_crit(dev, "Error executing keepalive: 0x%x\n", ret);
76	}
77
78	return ret;
79}
80
81static int wdt_stop(struct watchdog_device *wd)
82{
83	int ret;
84
85	ret = wdt_command(SCU_WATCHDOG_STOP, NULL, 0);
86	if (ret) {
87		struct device *dev = watchdog_get_drvdata(wd);
88		dev_crit(dev, "Error stopping watchdog: 0x%x\n", ret);
89	}
90
91	return ret;
92}
93
94static irqreturn_t mid_wdt_irq(int irq, void *dev_id)
95{
96	panic("Kernel Watchdog");
97
98	/* This code should not be reached */
99	return IRQ_HANDLED;
100}
101
102static const struct watchdog_info mid_wdt_info = {
103	.identity = "Intel MID SCU watchdog",
104	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
105};
106
107static const struct watchdog_ops mid_wdt_ops = {
108	.owner = THIS_MODULE,
109	.start = wdt_start,
110	.stop = wdt_stop,
111	.ping = wdt_ping,
112};
113
114static int mid_wdt_probe(struct platform_device *pdev)
115{
116	struct watchdog_device *wdt_dev;
117	struct intel_mid_wdt_pdata *pdata = pdev->dev.platform_data;
118	int ret;
119
120	if (!pdata) {
121		dev_err(&pdev->dev, "missing platform data\n");
122		return -EINVAL;
123	}
124
125	if (pdata->probe) {
126		ret = pdata->probe(pdev);
127		if (ret)
128			return ret;
129	}
130
131	wdt_dev = devm_kzalloc(&pdev->dev, sizeof(*wdt_dev), GFP_KERNEL);
132	if (!wdt_dev)
133		return -ENOMEM;
134
135	wdt_dev->info = &mid_wdt_info;
136	wdt_dev->ops = &mid_wdt_ops;
137	wdt_dev->min_timeout = MID_WDT_TIMEOUT_MIN;
138	wdt_dev->max_timeout = MID_WDT_TIMEOUT_MAX;
139	wdt_dev->timeout = MID_WDT_DEFAULT_TIMEOUT;
140
141	watchdog_set_drvdata(wdt_dev, &pdev->dev);
142	platform_set_drvdata(pdev, wdt_dev);
143
144	ret = devm_request_irq(&pdev->dev, pdata->irq, mid_wdt_irq,
145			       IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog",
146			       wdt_dev);
147	if (ret) {
148		dev_err(&pdev->dev, "error requesting warning irq %d\n",
149			pdata->irq);
150		return ret;
151	}
152
153	ret = watchdog_register_device(wdt_dev);
154	if (ret) {
155		dev_err(&pdev->dev, "error registering watchdog device\n");
156		return ret;
157	}
158
159	dev_info(&pdev->dev, "Intel MID watchdog device probed\n");
160
161	return 0;
162}
163
164static int mid_wdt_remove(struct platform_device *pdev)
165{
166	struct watchdog_device *wd = platform_get_drvdata(pdev);
167	watchdog_unregister_device(wd);
168	return 0;
169}
170
171static struct platform_driver mid_wdt_driver = {
172	.probe		= mid_wdt_probe,
173	.remove		= mid_wdt_remove,
174	.driver		= {
175		.owner	= THIS_MODULE,
176		.name	= "intel_mid_wdt",
177	},
178};
179
180module_platform_driver(mid_wdt_driver);
181
182MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
183MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform");
184MODULE_LICENSE("GPL");
185