1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * Copyright (C) 2015 Broadcom Corporation
  4 *
  5 */
  6
  7#include <linux/clk.h>
  8#include <linux/init.h>
  9#include <linux/io.h>
 10#include <linux/module.h>
 11#include <linux/of.h>
 12#include <linux/platform_device.h>
 13#include <linux/pm.h>
 14#include <linux/watchdog.h>
 15
 16#define WDT_START_1		0xff00
 17#define WDT_START_2		0x00ff
 18#define WDT_STOP_1		0xee00
 19#define WDT_STOP_2		0x00ee
 20
 21#define WDT_TIMEOUT_REG		0x0
 22#define WDT_CMD_REG		0x4
 23
 24#define WDT_MIN_TIMEOUT		1 /* seconds */
 25#define WDT_DEFAULT_TIMEOUT	30 /* seconds */
 26#define WDT_DEFAULT_RATE	27000000
 27
 28struct bcm7038_watchdog {
 29	void __iomem		*base;
 30	struct watchdog_device	wdd;
 31	u32			rate;
 32	struct clk		*clk;
 33};
 34
 35static bool nowayout = WATCHDOG_NOWAYOUT;
 36
 37static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
 38{
 39	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
 40	u32 timeout;
 41
 42	timeout = wdt->rate * wdog->timeout;
 43
 44	writel(timeout, wdt->base + WDT_TIMEOUT_REG);
 45}
 46
 47static int bcm7038_wdt_ping(struct watchdog_device *wdog)
 48{
 49	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
 50
 51	writel(WDT_START_1, wdt->base + WDT_CMD_REG);
 52	writel(WDT_START_2, wdt->base + WDT_CMD_REG);
 53
 54	return 0;
 55}
 56
 57static int bcm7038_wdt_start(struct watchdog_device *wdog)
 58{
 59	bcm7038_wdt_set_timeout_reg(wdog);
 60	bcm7038_wdt_ping(wdog);
 61
 62	return 0;
 63}
 64
 65static int bcm7038_wdt_stop(struct watchdog_device *wdog)
 66{
 67	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
 68
 69	writel(WDT_STOP_1, wdt->base + WDT_CMD_REG);
 70	writel(WDT_STOP_2, wdt->base + WDT_CMD_REG);
 71
 72	return 0;
 73}
 74
 75static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog,
 76				   unsigned int t)
 77{
 78	/* Can't modify timeout value if watchdog timer is running */
 79	bcm7038_wdt_stop(wdog);
 80	wdog->timeout = t;
 81	bcm7038_wdt_start(wdog);
 82
 83	return 0;
 84}
 85
 86static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
 87{
 88	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
 89	u32 time_left;
 90
 91	time_left = readl(wdt->base + WDT_CMD_REG);
 92
 93	return time_left / wdt->rate;
 94}
 95
 96static const struct watchdog_info bcm7038_wdt_info = {
 97	.identity	= "Broadcom BCM7038 Watchdog Timer",
 98	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 99				WDIOF_MAGICCLOSE
100};
101
102static const struct watchdog_ops bcm7038_wdt_ops = {
103	.owner		= THIS_MODULE,
104	.start		= bcm7038_wdt_start,
105	.stop		= bcm7038_wdt_stop,
106	.set_timeout	= bcm7038_wdt_set_timeout,
107	.get_timeleft	= bcm7038_wdt_get_timeleft,
108};
109
110static void bcm7038_clk_disable_unprepare(void *data)
111{
112	clk_disable_unprepare(data);
113}
114
115static int bcm7038_wdt_probe(struct platform_device *pdev)
116{
117	struct device *dev = &pdev->dev;
118	struct bcm7038_watchdog *wdt;
119	int err;
120
121	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
122	if (!wdt)
123		return -ENOMEM;
124
125	platform_set_drvdata(pdev, wdt);
126
127	wdt->base = devm_platform_ioremap_resource(pdev, 0);
128	if (IS_ERR(wdt->base))
129		return PTR_ERR(wdt->base);
130
131	wdt->clk = devm_clk_get(dev, NULL);
132	/* If unable to get clock, use default frequency */
133	if (!IS_ERR(wdt->clk)) {
134		err = clk_prepare_enable(wdt->clk);
135		if (err)
136			return err;
137		err = devm_add_action_or_reset(dev,
138					       bcm7038_clk_disable_unprepare,
139					       wdt->clk);
140		if (err)
141			return err;
142		wdt->rate = clk_get_rate(wdt->clk);
143		/* Prevent divide-by-zero exception */
144		if (!wdt->rate)
145			wdt->rate = WDT_DEFAULT_RATE;
146	} else {
147		wdt->rate = WDT_DEFAULT_RATE;
148		wdt->clk = NULL;
149	}
150
151	wdt->wdd.info		= &bcm7038_wdt_info;
152	wdt->wdd.ops		= &bcm7038_wdt_ops;
153	wdt->wdd.min_timeout	= WDT_MIN_TIMEOUT;
154	wdt->wdd.timeout	= WDT_DEFAULT_TIMEOUT;
155	wdt->wdd.max_timeout	= 0xffffffff / wdt->rate;
156	wdt->wdd.parent		= dev;
157	watchdog_set_drvdata(&wdt->wdd, wdt);
158
159	watchdog_stop_on_reboot(&wdt->wdd);
160	watchdog_stop_on_unregister(&wdt->wdd);
161	err = devm_watchdog_register_device(dev, &wdt->wdd);
162	if (err)
163		return err;
164
165	dev_info(dev, "Registered BCM7038 Watchdog\n");
166
167	return 0;
168}
169
170#ifdef CONFIG_PM_SLEEP
171static int bcm7038_wdt_suspend(struct device *dev)
172{
173	struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
174
175	if (watchdog_active(&wdt->wdd))
176		return bcm7038_wdt_stop(&wdt->wdd);
177
178	return 0;
179}
180
181static int bcm7038_wdt_resume(struct device *dev)
182{
183	struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
184
185	if (watchdog_active(&wdt->wdd))
186		return bcm7038_wdt_start(&wdt->wdd);
187
188	return 0;
189}
190#endif
191
192static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend,
193			 bcm7038_wdt_resume);
194
195static const struct of_device_id bcm7038_wdt_match[] = {
196	{ .compatible = "brcm,bcm7038-wdt" },
197	{},
198};
199MODULE_DEVICE_TABLE(of, bcm7038_wdt_match);
200
201static struct platform_driver bcm7038_wdt_driver = {
202	.probe		= bcm7038_wdt_probe,
203	.driver		= {
204		.name		= "bcm7038-wdt",
205		.of_match_table	= bcm7038_wdt_match,
206		.pm		= &bcm7038_wdt_pm_ops,
207	}
208};
209module_platform_driver(bcm7038_wdt_driver);
210
211module_param(nowayout, bool, 0);
212MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
213	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
214MODULE_LICENSE("GPL");
215MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
216MODULE_AUTHOR("Justin Chen");