1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * COMEDI driver for the watchdog subdevice found on some addi-data boards
4 * Copyright (c) 2013 H Hartley Sweeten <hsweeten@visionengravers.com>
5 *
6 * Based on implementations in various addi-data COMEDI drivers.
7 *
8 * COMEDI - Linux Control and Measurement Device Interface
9 * Copyright (C) 1998 David A. Schleef <ds@schleef.org>
10 */
11
12#include <linux/module.h>
13#include <linux/comedi/comedidev.h>
14#include "addi_tcw.h"
15#include "addi_watchdog.h"
16
17struct addi_watchdog_private {
18	unsigned long iobase;
19	unsigned int wdog_ctrl;
20};
21
22/*
23 * The watchdog subdevice is configured with two INSN_CONFIG instructions:
24 *
25 * Enable the watchdog and set the reload timeout:
26 *	data[0] = INSN_CONFIG_ARM
27 *	data[1] = timeout reload value
28 *
29 * Disable the watchdog:
30 *	data[0] = INSN_CONFIG_DISARM
31 */
32static int addi_watchdog_insn_config(struct comedi_device *dev,
33				     struct comedi_subdevice *s,
34				     struct comedi_insn *insn,
35				     unsigned int *data)
36{
37	struct addi_watchdog_private *spriv = s->private;
38	unsigned int reload;
39
40	switch (data[0]) {
41	case INSN_CONFIG_ARM:
42		spriv->wdog_ctrl = ADDI_TCW_CTRL_ENA;
43		reload = data[1] & s->maxdata;
44		outl(reload, spriv->iobase + ADDI_TCW_RELOAD_REG);
45
46		/* Time base is 20ms, let the user know the timeout */
47		dev_info(dev->class_dev, "watchdog enabled, timeout:%dms\n",
48			 20 * reload + 20);
49		break;
50	case INSN_CONFIG_DISARM:
51		spriv->wdog_ctrl = 0;
52		break;
53	default:
54		return -EINVAL;
55	}
56
57	outl(spriv->wdog_ctrl, spriv->iobase + ADDI_TCW_CTRL_REG);
58
59	return insn->n;
60}
61
62static int addi_watchdog_insn_read(struct comedi_device *dev,
63				   struct comedi_subdevice *s,
64				   struct comedi_insn *insn,
65				   unsigned int *data)
66{
67	struct addi_watchdog_private *spriv = s->private;
68	int i;
69
70	for (i = 0; i < insn->n; i++)
71		data[i] = inl(spriv->iobase + ADDI_TCW_STATUS_REG);
72
73	return insn->n;
74}
75
76static int addi_watchdog_insn_write(struct comedi_device *dev,
77				    struct comedi_subdevice *s,
78				    struct comedi_insn *insn,
79				    unsigned int *data)
80{
81	struct addi_watchdog_private *spriv = s->private;
82	int i;
83
84	if (spriv->wdog_ctrl == 0) {
85		dev_warn(dev->class_dev, "watchdog is disabled\n");
86		return -EINVAL;
87	}
88
89	/* "ping" the watchdog */
90	for (i = 0; i < insn->n; i++) {
91		outl(spriv->wdog_ctrl | ADDI_TCW_CTRL_TRIG,
92		     spriv->iobase + ADDI_TCW_CTRL_REG);
93	}
94
95	return insn->n;
96}
97
98void addi_watchdog_reset(unsigned long iobase)
99{
100	outl(0x0, iobase + ADDI_TCW_CTRL_REG);
101	outl(0x0, iobase + ADDI_TCW_RELOAD_REG);
102}
103EXPORT_SYMBOL_GPL(addi_watchdog_reset);
104
105int addi_watchdog_init(struct comedi_subdevice *s, unsigned long iobase)
106{
107	struct addi_watchdog_private *spriv;
108
109	spriv = comedi_alloc_spriv(s, sizeof(*spriv));
110	if (!spriv)
111		return -ENOMEM;
112
113	spriv->iobase = iobase;
114
115	s->type		= COMEDI_SUBD_TIMER;
116	s->subdev_flags	= SDF_WRITABLE;
117	s->n_chan	= 1;
118	s->maxdata	= 0xff;
119	s->insn_config	= addi_watchdog_insn_config;
120	s->insn_read	= addi_watchdog_insn_read;
121	s->insn_write	= addi_watchdog_insn_write;
122
123	return 0;
124}
125EXPORT_SYMBOL_GPL(addi_watchdog_init);
126
127static int __init addi_watchdog_module_init(void)
128{
129	return 0;
130}
131module_init(addi_watchdog_module_init);
132
133static void __exit addi_watchdog_module_exit(void)
134{
135}
136module_exit(addi_watchdog_module_exit);
137
138MODULE_DESCRIPTION("ADDI-DATA Watchdog subdevice");
139MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
140MODULE_LICENSE("GPL");
141