1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Window watchdog device driver for Xilinx Versal WWDT
  4 *
  5 * Copyright (C) 2022 - 2023, Advanced Micro Devices, Inc.
  6 */
  7
  8#include <linux/clk.h>
  9#include <linux/interrupt.h>
 10#include <linux/io.h>
 11#include <linux/ioport.h>
 12#include <linux/math64.h>
 13#include <linux/mod_devicetable.h>
 14#include <linux/module.h>
 15#include <linux/platform_device.h>
 16#include <linux/watchdog.h>
 17
 18/* Max timeout is calculated at 100MHz source clock */
 19#define XWWDT_DEFAULT_TIMEOUT	42
 20#define XWWDT_MIN_TIMEOUT	1
 21
 22/* Register offsets for the WWDT device */
 23#define XWWDT_MWR_OFFSET	0x00
 24#define XWWDT_ESR_OFFSET	0x04
 25#define XWWDT_FCR_OFFSET	0x08
 26#define XWWDT_FWR_OFFSET	0x0c
 27#define XWWDT_SWR_OFFSET	0x10
 28
 29/* Master Write Control Register Masks */
 30#define XWWDT_MWR_MASK		BIT(0)
 31
 32/* Enable and Status Register Masks */
 33#define XWWDT_ESR_WINT_MASK	BIT(16)
 34#define XWWDT_ESR_WSW_MASK	BIT(8)
 35#define XWWDT_ESR_WEN_MASK	BIT(0)
 36
 37#define XWWDT_CLOSE_WINDOW_PERCENT	50
 38
 39static int wwdt_timeout;
 40static int closed_window_percent;
 41
 42module_param(wwdt_timeout, int, 0);
 43MODULE_PARM_DESC(wwdt_timeout,
 44		 "Watchdog time in seconds. (default="
 45		 __MODULE_STRING(XWWDT_DEFAULT_TIMEOUT) ")");
 46module_param(closed_window_percent, int, 0);
 47MODULE_PARM_DESC(closed_window_percent,
 48		 "Watchdog closed window percentage. (default="
 49		 __MODULE_STRING(XWWDT_CLOSE_WINDOW_PERCENT) ")");
 50/**
 51 * struct xwwdt_device - Watchdog device structure
 52 * @base: base io address of WDT device
 53 * @spinlock: spinlock for IO register access
 54 * @xilinx_wwdt_wdd: watchdog device structure
 55 * @freq: source clock frequency of WWDT
 56 * @close_percent: Closed window percent
 57 */
 58struct xwwdt_device {
 59	void __iomem *base;
 60	spinlock_t spinlock; /* spinlock for register handling */
 61	struct watchdog_device xilinx_wwdt_wdd;
 62	unsigned long freq;
 63	u32 close_percent;
 64};
 65
 66static int xilinx_wwdt_start(struct watchdog_device *wdd)
 67{
 68	struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
 69	struct watchdog_device *xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
 70	u64 time_out, closed_timeout, open_timeout;
 71	u32 control_status_reg;
 72
 73	/* Calculate timeout count */
 74	time_out = xdev->freq * wdd->timeout;
 75	closed_timeout = div_u64(time_out * xdev->close_percent, 100);
 76	open_timeout = time_out - closed_timeout;
 77	wdd->min_hw_heartbeat_ms = xdev->close_percent * 10 * wdd->timeout;
 78
 79	spin_lock(&xdev->spinlock);
 80
 81	iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
 82	iowrite32(~(u32)XWWDT_ESR_WEN_MASK, xdev->base + XWWDT_ESR_OFFSET);
 83	iowrite32((u32)closed_timeout, xdev->base + XWWDT_FWR_OFFSET);
 84	iowrite32((u32)open_timeout, xdev->base + XWWDT_SWR_OFFSET);
 85
 86	/* Enable the window watchdog timer */
 87	control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
 88	control_status_reg |= XWWDT_ESR_WEN_MASK;
 89	iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
 90
 91	spin_unlock(&xdev->spinlock);
 92
 93	dev_dbg(xilinx_wwdt_wdd->parent, "Watchdog Started!\n");
 94
 95	return 0;
 96}
 97
 98static int xilinx_wwdt_keepalive(struct watchdog_device *wdd)
 99{
100	struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
101	u32 control_status_reg;
102
103	spin_lock(&xdev->spinlock);
104
105	/* Enable write access control bit for the window watchdog */
106	iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
107
108	/* Trigger restart kick to watchdog */
109	control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
110	control_status_reg |= XWWDT_ESR_WSW_MASK;
111	iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
112
113	spin_unlock(&xdev->spinlock);
114
115	return 0;
116}
117
118static const struct watchdog_info xilinx_wwdt_ident = {
119	.options = WDIOF_KEEPALIVEPING |
120		WDIOF_SETTIMEOUT,
121	.firmware_version = 1,
122	.identity = "xlnx_window watchdog",
123};
124
125static const struct watchdog_ops xilinx_wwdt_ops = {
126	.owner = THIS_MODULE,
127	.start = xilinx_wwdt_start,
128	.ping = xilinx_wwdt_keepalive,
129};
130
131static int xwwdt_probe(struct platform_device *pdev)
132{
133	struct watchdog_device *xilinx_wwdt_wdd;
134	struct device *dev = &pdev->dev;
135	struct xwwdt_device *xdev;
136	struct clk *clk;
137	int ret;
138
139	xdev = devm_kzalloc(dev, sizeof(*xdev), GFP_KERNEL);
140	if (!xdev)
141		return -ENOMEM;
142
143	xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
144	xilinx_wwdt_wdd->info = &xilinx_wwdt_ident;
145	xilinx_wwdt_wdd->ops = &xilinx_wwdt_ops;
146	xilinx_wwdt_wdd->parent = dev;
147
148	xdev->base = devm_platform_ioremap_resource(pdev, 0);
149	if (IS_ERR(xdev->base))
150		return PTR_ERR(xdev->base);
151
152	clk = devm_clk_get_enabled(dev, NULL);
153	if (IS_ERR(clk))
154		return PTR_ERR(clk);
155
156	xdev->freq = clk_get_rate(clk);
157	if (!xdev->freq)
158		return -EINVAL;
159
160	xilinx_wwdt_wdd->min_timeout = XWWDT_MIN_TIMEOUT;
161	xilinx_wwdt_wdd->timeout = XWWDT_DEFAULT_TIMEOUT;
162	xilinx_wwdt_wdd->max_hw_heartbeat_ms = 1000 * xilinx_wwdt_wdd->timeout;
163
164	if (closed_window_percent == 0 || closed_window_percent >= 100)
165		xdev->close_percent = XWWDT_CLOSE_WINDOW_PERCENT;
166	else
167		xdev->close_percent = closed_window_percent;
168
169	watchdog_init_timeout(xilinx_wwdt_wdd, wwdt_timeout, &pdev->dev);
170	spin_lock_init(&xdev->spinlock);
171	watchdog_set_drvdata(xilinx_wwdt_wdd, xdev);
172	watchdog_set_nowayout(xilinx_wwdt_wdd, 1);
173
174	ret = devm_watchdog_register_device(dev, xilinx_wwdt_wdd);
175	if (ret)
176		return ret;
177
178	dev_info(dev, "Xilinx window watchdog Timer with timeout %ds\n",
179		 xilinx_wwdt_wdd->timeout);
180
181	return 0;
182}
183
184static const struct of_device_id xwwdt_of_match[] = {
185	{ .compatible = "xlnx,versal-wwdt", },
186	{},
187};
188MODULE_DEVICE_TABLE(of, xwwdt_of_match);
189
190static struct platform_driver xwwdt_driver = {
191	.probe = xwwdt_probe,
192	.driver = {
193		.name = "Xilinx window watchdog",
194		.of_match_table = xwwdt_of_match,
195	},
196};
197
198module_platform_driver(xwwdt_driver);
199
200MODULE_AUTHOR("Neeli Srinivas <srinivas.neeli@amd.com>");
201MODULE_DESCRIPTION("Xilinx window watchdog driver");
202MODULE_LICENSE("GPL");