1 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
2 /*
3  * Copyright (c) 2016 BayLibre, SAS.
4  * Author: Neil Armstrong <narmstrong@baylibre.com>
5  *
6  */
7 #include <linux/clk.h>
8 #include <linux/err.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/slab.h>
14 #include <linux/types.h>
15 #include <linux/watchdog.h>
16 
17 #define DEFAULT_TIMEOUT	30	/* seconds */
18 
19 #define GXBB_WDT_CTRL_REG			0x0
20 #define GXBB_WDT_TCNT_REG			0x8
21 #define GXBB_WDT_RSET_REG			0xc
22 
23 #define GXBB_WDT_CTRL_CLKDIV_EN			BIT(25)
24 #define GXBB_WDT_CTRL_CLK_EN			BIT(24)
25 #define GXBB_WDT_CTRL_EE_RESET			BIT(21)
26 #define GXBB_WDT_CTRL_EN			BIT(18)
27 #define GXBB_WDT_CTRL_DIV_MASK			(BIT(18) - 1)
28 
29 #define GXBB_WDT_TCNT_SETUP_MASK		(BIT(16) - 1)
30 #define GXBB_WDT_TCNT_CNT_SHIFT			16
31 
32 struct meson_gxbb_wdt {
33 	void __iomem *reg_base;
34 	struct watchdog_device wdt_dev;
35 	struct clk *clk;
36 };
37 
38 static int meson_gxbb_wdt_start(struct watchdog_device *wdt_dev)
39 {
40 	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
41 
42 	writel(readl(data->reg_base + GXBB_WDT_CTRL_REG) | GXBB_WDT_CTRL_EN,
43 	       data->reg_base + GXBB_WDT_CTRL_REG);
44 
45 	return 0;
46 }
47 
48 static int meson_gxbb_wdt_stop(struct watchdog_device *wdt_dev)
49 {
50 	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
51 
52 	writel(readl(data->reg_base + GXBB_WDT_CTRL_REG) & ~GXBB_WDT_CTRL_EN,
53 	       data->reg_base + GXBB_WDT_CTRL_REG);
54 
55 	return 0;
56 }
57 
58 static int meson_gxbb_wdt_ping(struct watchdog_device *wdt_dev)
59 {
60 	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
61 
62 	writel(0, data->reg_base + GXBB_WDT_RSET_REG);
63 
64 	return 0;
65 }
66 
67 static int meson_gxbb_wdt_set_timeout(struct watchdog_device *wdt_dev,
68 				      unsigned int timeout)
69 {
70 	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
71 	unsigned long tcnt = timeout * 1000;
72 
73 	if (tcnt > GXBB_WDT_TCNT_SETUP_MASK)
74 		tcnt = GXBB_WDT_TCNT_SETUP_MASK;
75 
76 	wdt_dev->timeout = timeout;
77 
78 	meson_gxbb_wdt_ping(wdt_dev);
79 
80 	writel(tcnt, data->reg_base + GXBB_WDT_TCNT_REG);
81 
82 	return 0;
83 }
84 
85 static unsigned int meson_gxbb_wdt_get_timeleft(struct watchdog_device *wdt_dev)
86 {
87 	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
88 	unsigned long reg;
89 
90 	reg = readl(data->reg_base + GXBB_WDT_TCNT_REG);
91 
92 	return ((reg >> GXBB_WDT_TCNT_CNT_SHIFT) -
93 		(reg & GXBB_WDT_TCNT_SETUP_MASK)) / 1000;
94 }
95 
96 static const struct watchdog_ops meson_gxbb_wdt_ops = {
97 	.start = meson_gxbb_wdt_start,
98 	.stop = meson_gxbb_wdt_stop,
99 	.ping = meson_gxbb_wdt_ping,
100 	.set_timeout = meson_gxbb_wdt_set_timeout,
101 	.get_timeleft = meson_gxbb_wdt_get_timeleft,
102 };
103 
104 static const struct watchdog_info meson_gxbb_wdt_info = {
105 	.identity = "Meson GXBB Watchdog",
106 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
107 };
108 
109 static int __maybe_unused meson_gxbb_wdt_resume(struct device *dev)
110 {
111 	struct meson_gxbb_wdt *data = dev_get_drvdata(dev);
112 
113 	if (watchdog_active(&data->wdt_dev))
114 		meson_gxbb_wdt_start(&data->wdt_dev);
115 
116 	return 0;
117 }
118 
119 static int __maybe_unused meson_gxbb_wdt_suspend(struct device *dev)
120 {
121 	struct meson_gxbb_wdt *data = dev_get_drvdata(dev);
122 
123 	if (watchdog_active(&data->wdt_dev))
124 		meson_gxbb_wdt_stop(&data->wdt_dev);
125 
126 	return 0;
127 }
128 
129 static const struct dev_pm_ops meson_gxbb_wdt_pm_ops = {
130 	SET_SYSTEM_SLEEP_PM_OPS(meson_gxbb_wdt_suspend, meson_gxbb_wdt_resume)
131 };
132 
133 static const struct of_device_id meson_gxbb_wdt_dt_ids[] = {
134 	 { .compatible = "amlogic,meson-gxbb-wdt", },
135 	 { /* sentinel */ },
136 };
137 MODULE_DEVICE_TABLE(of, meson_gxbb_wdt_dt_ids);
138 
139 static void meson_clk_disable_unprepare(void *data)
140 {
141 	clk_disable_unprepare(data);
142 }
143 
144 static int meson_gxbb_wdt_probe(struct platform_device *pdev)
145 {
146 	struct device *dev = &pdev->dev;
147 	struct meson_gxbb_wdt *data;
148 	int ret;
149 
150 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
151 	if (!data)
152 		return -ENOMEM;
153 
154 	data->reg_base = devm_platform_ioremap_resource(pdev, 0);
155 	if (IS_ERR(data->reg_base))
156 		return PTR_ERR(data->reg_base);
157 
158 	data->clk = devm_clk_get(dev, NULL);
159 	if (IS_ERR(data->clk))
160 		return PTR_ERR(data->clk);
161 
162 	ret = clk_prepare_enable(data->clk);
163 	if (ret)
164 		return ret;
165 	ret = devm_add_action_or_reset(dev, meson_clk_disable_unprepare,
166 				       data->clk);
167 	if (ret)
168 		return ret;
169 
170 	platform_set_drvdata(pdev, data);
171 
172 	data->wdt_dev.parent = dev;
173 	data->wdt_dev.info = &meson_gxbb_wdt_info;
174 	data->wdt_dev.ops = &meson_gxbb_wdt_ops;
175 	data->wdt_dev.max_hw_heartbeat_ms = GXBB_WDT_TCNT_SETUP_MASK;
176 	data->wdt_dev.min_timeout = 1;
177 	data->wdt_dev.timeout = DEFAULT_TIMEOUT;
178 	watchdog_set_drvdata(&data->wdt_dev, data);
179 
180 	/* Setup with 1ms timebase */
181 	writel(((clk_get_rate(data->clk) / 1000) & GXBB_WDT_CTRL_DIV_MASK) |
182 		GXBB_WDT_CTRL_EE_RESET |
183 		GXBB_WDT_CTRL_CLK_EN |
184 		GXBB_WDT_CTRL_CLKDIV_EN,
185 		data->reg_base + GXBB_WDT_CTRL_REG);
186 
187 	meson_gxbb_wdt_set_timeout(&data->wdt_dev, data->wdt_dev.timeout);
188 
189 	watchdog_stop_on_reboot(&data->wdt_dev);
190 	return devm_watchdog_register_device(dev, &data->wdt_dev);
191 }
192 
193 static struct platform_driver meson_gxbb_wdt_driver = {
194 	.probe	= meson_gxbb_wdt_probe,
195 	.driver = {
196 		.name = "meson-gxbb-wdt",
197 		.pm = &meson_gxbb_wdt_pm_ops,
198 		.of_match_table	= meson_gxbb_wdt_dt_ids,
199 	},
200 };
201 
202 module_platform_driver(meson_gxbb_wdt_driver);
203 
204 MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
205 MODULE_DESCRIPTION("Amlogic Meson GXBB Watchdog timer driver");
206 MODULE_LICENSE("Dual BSD/GPL");
207