visconti_wdt.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (c) 2020 TOSHIBA CORPORATION
  4 * Copyright (c) 2020 Toshiba Electronic Devices & Storage Corporation
  5 * Copyright (c) 2020 Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
  6 */
  7
  8#include <linux/clk.h>
  9#include <linux/io.h>
 10#include <linux/kernel.h>
 11#include <linux/module.h>
 12#include <linux/of.h>
 13#include <linux/platform_device.h>
 14#include <linux/watchdog.h>
 15
 16#define WDT_CNT			0x00
 17#define WDT_MIN			0x04
 18#define WDT_MAX			0x08
 19#define WDT_CTL			0x0c
 20#define WDT_CMD			0x10
 21#define WDT_CMD_CLEAR		0x4352
 22#define WDT_CMD_START_STOP	0x5354
 23#define WDT_DIV			0x30
 24
 25#define VISCONTI_WDT_FREQ	2000000 /* 2MHz */
 26#define WDT_DEFAULT_TIMEOUT	10U /* in seconds */
 27
 28static bool nowayout = WATCHDOG_NOWAYOUT;
 29module_param(nowayout, bool, 0);
 30MODULE_PARM_DESC(
 31	nowayout,
 32	"Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT)")");
 33
 34struct visconti_wdt_priv {
 35	struct watchdog_device wdev;
 36	void __iomem *base;
 37	u32 div;
 38};
 39
 40static int visconti_wdt_start(struct watchdog_device *wdev)
 41{
 42	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
 43	u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
 44
 45	writel(priv->div, priv->base + WDT_DIV);
 46	writel(0, priv->base + WDT_MIN);
 47	writel(timeout, priv->base + WDT_MAX);
 48	writel(0, priv->base + WDT_CTL);
 49	writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
 50
 51	return 0;
 52}
 53
 54static int visconti_wdt_stop(struct watchdog_device *wdev)
 55{
 56	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
 57
 58	writel(1, priv->base + WDT_CTL);
 59	writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
 60
 61	return 0;
 62}
 63
 64static int visconti_wdt_ping(struct watchdog_device *wdd)
 65{
 66	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd);
 67
 68	writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
 69
 70	return 0;
 71}
 72
 73static unsigned int visconti_wdt_get_timeleft(struct watchdog_device *wdev)
 74{
 75	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
 76	u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
 77	u32 cnt = readl(priv->base + WDT_CNT);
 78
 79	if (timeout <= cnt)
 80		return 0;
 81	timeout -= cnt;
 82
 83	return timeout / VISCONTI_WDT_FREQ;
 84}
 85
 86static int visconti_wdt_set_timeout(struct watchdog_device *wdev, unsigned int timeout)
 87{
 88	u32 val;
 89	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
 90
 91	wdev->timeout = timeout;
 92	val = wdev->timeout * VISCONTI_WDT_FREQ;
 93
 94	/* Clear counter before setting timeout because WDT expires */
 95	writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
 96	writel(val, priv->base + WDT_MAX);
 97
 98	return 0;
 99}
100
101static const struct watchdog_info visconti_wdt_info = {
102	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
103	.identity = "Visconti Watchdog",
104};
105
106static const struct watchdog_ops visconti_wdt_ops = {
107	.owner		= THIS_MODULE,
108	.start		= visconti_wdt_start,
109	.stop		= visconti_wdt_stop,
110	.ping		= visconti_wdt_ping,
111	.get_timeleft	= visconti_wdt_get_timeleft,
112	.set_timeout	= visconti_wdt_set_timeout,
113};
114
115static int visconti_wdt_probe(struct platform_device *pdev)
116{
117	struct watchdog_device *wdev;
118	struct visconti_wdt_priv *priv;
119	struct device *dev = &pdev->dev;
120	struct clk *clk;
121	unsigned long clk_freq;
122
123	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
124	if (!priv)
125		return -ENOMEM;
126
127	priv->base = devm_platform_ioremap_resource(pdev, 0);
128	if (IS_ERR(priv->base))
129		return PTR_ERR(priv->base);
130
131	clk = devm_clk_get_enabled(dev, NULL);
132	if (IS_ERR(clk))
133		return dev_err_probe(dev, PTR_ERR(clk), "Could not get clock\n");
134
135	clk_freq = clk_get_rate(clk);
136	if (!clk_freq)
137		return -EINVAL;
138
139	priv->div = clk_freq / VISCONTI_WDT_FREQ;
140
141	/* Initialize struct watchdog_device. */
142	wdev = &priv->wdev;
143	wdev->info = &visconti_wdt_info;
144	wdev->ops = &visconti_wdt_ops;
145	wdev->parent = dev;
146	wdev->min_timeout = 1;
147	wdev->max_timeout = 0xffffffff / VISCONTI_WDT_FREQ;
148	wdev->timeout = min(wdev->max_timeout, WDT_DEFAULT_TIMEOUT);
149
150	watchdog_set_drvdata(wdev, priv);
151	watchdog_set_nowayout(wdev, nowayout);
152	watchdog_stop_on_unregister(wdev);
153
154	/* This overrides the default timeout only if DT configuration was found */
155	watchdog_init_timeout(wdev, 0, dev);
156
157	return devm_watchdog_register_device(dev, wdev);
158}
159
160static const struct of_device_id visconti_wdt_of_match[] = {
161	{ .compatible = "toshiba,visconti-wdt", },
162	{}
163};
164MODULE_DEVICE_TABLE(of, visconti_wdt_of_match);
165
166static struct platform_driver visconti_wdt_driver = {
167	.driver = {
168			.name = "visconti_wdt",
169			.of_match_table = visconti_wdt_of_match,
170		},
171	.probe = visconti_wdt_probe,
172};
173module_platform_driver(visconti_wdt_driver);
174
175MODULE_DESCRIPTION("TOSHIBA Visconti Watchdog Driver");
176MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp");
177MODULE_LICENSE("GPL v2");