nct6694_wdt.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Nuvoton NCT6694 WDT driver based on USB interface.
  4 *
  5 * Copyright (C) 2025 Nuvoton Technology Corp.
  6 */
  7
  8#include <linux/idr.h>
  9#include <linux/kernel.h>
 10#include <linux/mfd/nct6694.h>
 11#include <linux/module.h>
 12#include <linux/platform_device.h>
 13#include <linux/slab.h>
 14#include <linux/watchdog.h>
 15
 16#define DEVICE_NAME "nct6694-wdt"
 17
 18#define NCT6694_DEFAULT_TIMEOUT		10
 19#define NCT6694_DEFAULT_PRETIMEOUT	0
 20
 21#define NCT6694_WDT_MAX_DEVS		2
 22
 23/*
 24 * USB command module type for NCT6694 WDT controller.
 25 * This defines the module type used for communication with the NCT6694
 26 * WDT controller over the USB interface.
 27 */
 28#define NCT6694_WDT_MOD			0x07
 29
 30/* Command 00h - WDT Setup */
 31#define NCT6694_WDT_SETUP		0x00
 32#define NCT6694_WDT_SETUP_SEL(idx)	(idx ? 0x01 : 0x00)
 33
 34/* Command 01h - WDT Command */
 35#define NCT6694_WDT_COMMAND		0x01
 36#define NCT6694_WDT_COMMAND_SEL(idx)	(idx ? 0x01 : 0x00)
 37
 38static unsigned int timeout[NCT6694_WDT_MAX_DEVS] = {
 39	[0 ... (NCT6694_WDT_MAX_DEVS - 1)] = NCT6694_DEFAULT_TIMEOUT
 40};
 41module_param_array(timeout, int, NULL, 0644);
 42MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
 43
 44static unsigned int pretimeout[NCT6694_WDT_MAX_DEVS] = {
 45	[0 ... (NCT6694_WDT_MAX_DEVS - 1)] = NCT6694_DEFAULT_PRETIMEOUT
 46};
 47module_param_array(pretimeout, int, NULL, 0644);
 48MODULE_PARM_DESC(pretimeout, "Watchdog pre-timeout in seconds");
 49
 50static bool nowayout = WATCHDOG_NOWAYOUT;
 51module_param(nowayout, bool, 0);
 52MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 53			   __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 54
 55enum {
 56	NCT6694_ACTION_NONE = 0,
 57	NCT6694_ACTION_SIRQ,
 58	NCT6694_ACTION_GPO,
 59};
 60
 61struct __packed nct6694_wdt_setup {
 62	__le32 pretimeout;
 63	__le32 timeout;
 64	u8 owner;
 65	u8 scratch;
 66	u8 control;
 67	u8 status;
 68	__le32 countdown;
 69};
 70
 71struct __packed nct6694_wdt_cmd {
 72	__le32 wdt_cmd;
 73	__le32 reserved;
 74};
 75
 76union __packed nct6694_wdt_msg {
 77	struct nct6694_wdt_setup setup;
 78	struct nct6694_wdt_cmd cmd;
 79};
 80
 81struct nct6694_wdt_data {
 82	struct watchdog_device wdev;
 83	struct device *dev;
 84	struct nct6694 *nct6694;
 85	union nct6694_wdt_msg *msg;
 86	unsigned char wdev_idx;
 87};
 88
 89static int nct6694_wdt_setting(struct watchdog_device *wdev,
 90			       u32 timeout_val, u8 timeout_act,
 91			       u32 pretimeout_val, u8 pretimeout_act)
 92{
 93	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
 94	struct nct6694_wdt_setup *setup = &data->msg->setup;
 95	const struct nct6694_cmd_header cmd_hd = {
 96		.mod = NCT6694_WDT_MOD,
 97		.cmd = NCT6694_WDT_SETUP,
 98		.sel = NCT6694_WDT_SETUP_SEL(data->wdev_idx),
 99		.len = cpu_to_le16(sizeof(*setup))
100	};
101	unsigned int timeout_fmt, pretimeout_fmt;
102
103	if (pretimeout_val == 0)
104		pretimeout_act = NCT6694_ACTION_NONE;
105
106	timeout_fmt = (timeout_val * 1000) | (timeout_act << 24);
107	pretimeout_fmt = (pretimeout_val * 1000) | (pretimeout_act << 24);
108
109	memset(setup, 0, sizeof(*setup));
110	setup->timeout = cpu_to_le32(timeout_fmt);
111	setup->pretimeout = cpu_to_le32(pretimeout_fmt);
112
113	return nct6694_write_msg(data->nct6694, &cmd_hd, setup);
114}
115
116static int nct6694_wdt_start(struct watchdog_device *wdev)
117{
118	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
119	int ret;
120
121	ret = nct6694_wdt_setting(wdev, wdev->timeout, NCT6694_ACTION_GPO,
122				  wdev->pretimeout, NCT6694_ACTION_GPO);
123	if (ret)
124		return ret;
125
126	dev_dbg(data->dev, "Setting WDT(%d): timeout = %d, pretimeout = %d\n",
127		data->wdev_idx, wdev->timeout, wdev->pretimeout);
128
129	return ret;
130}
131
132static int nct6694_wdt_stop(struct watchdog_device *wdev)
133{
134	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
135	struct nct6694_wdt_cmd *cmd = &data->msg->cmd;
136	const struct nct6694_cmd_header cmd_hd = {
137		.mod = NCT6694_WDT_MOD,
138		.cmd = NCT6694_WDT_COMMAND,
139		.sel = NCT6694_WDT_COMMAND_SEL(data->wdev_idx),
140		.len = cpu_to_le16(sizeof(*cmd))
141	};
142
143	memcpy(&cmd->wdt_cmd, "WDTC", 4);
144	cmd->reserved = 0;
145
146	return nct6694_write_msg(data->nct6694, &cmd_hd, cmd);
147}
148
149static int nct6694_wdt_ping(struct watchdog_device *wdev)
150{
151	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
152	struct nct6694_wdt_cmd *cmd = &data->msg->cmd;
153	const struct nct6694_cmd_header cmd_hd = {
154		.mod = NCT6694_WDT_MOD,
155		.cmd = NCT6694_WDT_COMMAND,
156		.sel = NCT6694_WDT_COMMAND_SEL(data->wdev_idx),
157		.len = cpu_to_le16(sizeof(*cmd))
158	};
159
160	memcpy(&cmd->wdt_cmd, "WDTS", 4);
161	cmd->reserved = 0;
162
163	return nct6694_write_msg(data->nct6694, &cmd_hd, cmd);
164}
165
166static int nct6694_wdt_set_timeout(struct watchdog_device *wdev,
167				   unsigned int new_timeout)
168{
169	int ret;
170
171	ret = nct6694_wdt_setting(wdev, new_timeout, NCT6694_ACTION_GPO,
172				  wdev->pretimeout, NCT6694_ACTION_GPO);
173	if (ret)
174		return ret;
175
176	wdev->timeout = new_timeout;
177
178	return 0;
179}
180
181static int nct6694_wdt_set_pretimeout(struct watchdog_device *wdev,
182				      unsigned int new_pretimeout)
183{
184	int ret;
185
186	ret = nct6694_wdt_setting(wdev, wdev->timeout, NCT6694_ACTION_GPO,
187				  new_pretimeout, NCT6694_ACTION_GPO);
188	if (ret)
189		return ret;
190
191	wdev->pretimeout = new_pretimeout;
192
193	return 0;
194}
195
196static unsigned int nct6694_wdt_get_time(struct watchdog_device *wdev)
197{
198	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
199	struct nct6694_wdt_setup *setup = &data->msg->setup;
200	const struct nct6694_cmd_header cmd_hd = {
201		.mod = NCT6694_WDT_MOD,
202		.cmd = NCT6694_WDT_SETUP,
203		.sel = NCT6694_WDT_SETUP_SEL(data->wdev_idx),
204		.len = cpu_to_le16(sizeof(*setup))
205	};
206	unsigned int timeleft_ms;
207	int ret;
208
209	ret = nct6694_read_msg(data->nct6694, &cmd_hd, setup);
210	if (ret)
211		return 0;
212
213	timeleft_ms = le32_to_cpu(setup->countdown);
214
215	return timeleft_ms / 1000;
216}
217
218static const struct watchdog_info nct6694_wdt_info = {
219	.options = WDIOF_SETTIMEOUT	|
220		   WDIOF_KEEPALIVEPING	|
221		   WDIOF_MAGICCLOSE	|
222		   WDIOF_PRETIMEOUT,
223	.identity = DEVICE_NAME,
224};
225
226static const struct watchdog_ops nct6694_wdt_ops = {
227	.owner = THIS_MODULE,
228	.start = nct6694_wdt_start,
229	.stop = nct6694_wdt_stop,
230	.set_timeout = nct6694_wdt_set_timeout,
231	.set_pretimeout = nct6694_wdt_set_pretimeout,
232	.get_timeleft = nct6694_wdt_get_time,
233	.ping = nct6694_wdt_ping,
234};
235
236static void nct6694_wdt_ida_free(void *d)
237{
238	struct nct6694_wdt_data *data = d;
239	struct nct6694 *nct6694 = data->nct6694;
240
241	ida_free(&nct6694->wdt_ida, data->wdev_idx);
242}
243
244static int nct6694_wdt_probe(struct platform_device *pdev)
245{
246	struct device *dev = &pdev->dev;
247	struct nct6694 *nct6694 = dev_get_drvdata(dev->parent);
248	struct nct6694_wdt_data *data;
249	struct watchdog_device *wdev;
250	int ret;
251
252	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
253	if (!data)
254		return -ENOMEM;
255
256	data->msg = devm_kzalloc(dev, sizeof(union nct6694_wdt_msg),
257				 GFP_KERNEL);
258	if (!data->msg)
259		return -ENOMEM;
260
261	data->dev = dev;
262	data->nct6694 = nct6694;
263
264	ret = ida_alloc(&nct6694->wdt_ida, GFP_KERNEL);
265	if (ret < 0)
266		return ret;
267	data->wdev_idx = ret;
268
269	ret = devm_add_action_or_reset(dev, nct6694_wdt_ida_free, data);
270	if (ret)
271		return ret;
272
273	wdev = &data->wdev;
274	wdev->info = &nct6694_wdt_info;
275	wdev->ops = &nct6694_wdt_ops;
276	wdev->timeout = timeout[data->wdev_idx];
277	wdev->pretimeout = pretimeout[data->wdev_idx];
278	if (timeout[data->wdev_idx] < pretimeout[data->wdev_idx]) {
279		dev_warn(data->dev, "pretimeout < timeout. Setting to zero\n");
280		wdev->pretimeout = 0;
281	}
282
283	wdev->min_timeout = 1;
284	wdev->max_timeout = 255;
285
286	platform_set_drvdata(pdev, data);
287
288	watchdog_set_drvdata(&data->wdev, data);
289	watchdog_set_nowayout(&data->wdev, nowayout);
290	watchdog_stop_on_reboot(&data->wdev);
291
292	return devm_watchdog_register_device(dev, &data->wdev);
293}
294
295static struct platform_driver nct6694_wdt_driver = {
296	.driver = {
297		.name	= DEVICE_NAME,
298	},
299	.probe		= nct6694_wdt_probe,
300};
301
302module_platform_driver(nct6694_wdt_driver);
303
304MODULE_DESCRIPTION("USB-WDT driver for NCT6694");
305MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
306MODULE_LICENSE("GPL");
307MODULE_ALIAS("platform:nct6694-wdt");