blob: 2d264971d839809d70ba8fe780ed3ba6ef89ff33 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * NetWinder Button Driver-
3 * Copyright (C) Alex Holden <alex@linuxhacker.org> 1998, 1999.
4 *
5 */
6
Linus Torvalds1da177e2005-04-16 15:20:36 -07007#include <linux/module.h>
8#include <linux/kernel.h>
9#include <linux/sched.h>
10#include <linux/interrupt.h>
11#include <linux/time.h>
12#include <linux/timer.h>
13#include <linux/fs.h>
14#include <linux/miscdevice.h>
15#include <linux/string.h>
16#include <linux/errno.h>
17#include <linux/init.h>
18
19#include <asm/uaccess.h>
20#include <asm/irq.h>
21#include <asm/mach-types.h>
22
23#define __NWBUTTON_C /* Tell the header file who we are */
24#include "nwbutton.h"
25
26static int button_press_count; /* The count of button presses */
27static struct timer_list button_timer; /* Times for the end of a sequence */
28static DECLARE_WAIT_QUEUE_HEAD(button_wait_queue); /* Used for blocking read */
29static char button_output_buffer[32]; /* Stores data to write out of device */
30static int bcount; /* The number of bytes in the buffer */
31static int bdelay = BUTTON_DELAY; /* The delay, in jiffies */
32static struct button_callback button_callback_list[32]; /* The callback list */
33static int callback_count; /* The number of callbacks registered */
34static int reboot_count = NUM_PRESSES_REBOOT; /* Number of presses to reboot */
35
36/*
37 * This function is called by other drivers to register a callback function
38 * to be called when a particular number of button presses occurs.
39 * The callback list is a static array of 32 entries (I somehow doubt many
40 * people are ever going to want to register more than 32 different actions
41 * to be performed by the kernel on different numbers of button presses ;).
42 * However, if an attempt to register a 33rd entry (perhaps a stuck loop
43 * somewhere registering the same entry over and over?) it will fail to
44 * do so and return -ENOMEM. If an attempt is made to register a null pointer,
45 * it will fail to do so and return -EINVAL.
46 * Because callbacks can be unregistered at random the list can become
47 * fragmented, so we need to search through the list until we find the first
48 * free entry.
49 *
50 * FIXME: Has anyone spotted any locking functions int his code recently ??
51 */
52
53int button_add_callback (void (*callback) (void), int count)
54{
55 int lp = 0;
56 if (callback_count == 32) {
57 return -ENOMEM;
58 }
59 if (!callback) {
60 return -EINVAL;
61 }
62 callback_count++;
63 for (; (button_callback_list [lp].callback); lp++);
64 button_callback_list [lp].callback = callback;
65 button_callback_list [lp].count = count;
66 return 0;
67}
68
69/*
70 * This function is called by other drivers to deregister a callback function.
71 * If you attempt to unregister a callback which does not exist, it will fail
72 * with -EINVAL. If there is more than one entry with the same address,
73 * because it searches the list from end to beginning, it will unregister the
74 * last one to be registered first (FILO- First In Last Out).
75 * Note that this is not neccessarily true if the entries are not submitted
76 * at the same time, because another driver could have unregistered a callback
77 * between the submissions creating a gap earlier in the list, which would
78 * be filled first at submission time.
79 */
80
81int button_del_callback (void (*callback) (void))
82{
83 int lp = 31;
84 if (!callback) {
85 return -EINVAL;
86 }
87 while (lp >= 0) {
88 if ((button_callback_list [lp].callback) == callback) {
89 button_callback_list [lp].callback = NULL;
90 button_callback_list [lp].count = 0;
91 callback_count--;
92 return 0;
93 };
94 lp--;
95 };
96 return -EINVAL;
97}
98
99/*
100 * This function is called by button_sequence_finished to search through the
101 * list of callback functions, and call any of them whose count argument
102 * matches the current count of button presses. It starts at the beginning
103 * of the list and works up to the end. It will refuse to follow a null
104 * pointer (which should never happen anyway).
105 */
106
107static void button_consume_callbacks (int bpcount)
108{
109 int lp = 0;
110 for (; lp <= 31; lp++) {
111 if ((button_callback_list [lp].count) == bpcount) {
112 if (button_callback_list [lp].callback) {
113 button_callback_list[lp].callback();
114 }
115 }
116 }
117}
118
119/*
120 * This function is called when the button_timer times out.
121 * ie. When you don't press the button for bdelay jiffies, this is taken to
122 * mean you have ended the sequence of key presses, and this function is
123 * called to wind things up (write the press_count out to /dev/button, call
124 * any matching registered function callbacks, initiate reboot, etc.).
125 */
126
127static void button_sequence_finished (unsigned long parameters)
128{
129#ifdef CONFIG_NWBUTTON_REBOOT /* Reboot using button is enabled */
Cedric Le Goater9ec52092006-10-02 02:19:00 -0700130 if (button_press_count == reboot_count)
131 kill_cad_pid(SIGINT, 1); /* Ask init to reboot us */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132#endif /* CONFIG_NWBUTTON_REBOOT */
133 button_consume_callbacks (button_press_count);
134 bcount = sprintf (button_output_buffer, "%d\n", button_press_count);
135 button_press_count = 0; /* Reset the button press counter */
136 wake_up_interruptible (&button_wait_queue);
137}
138
139/*
140 * This handler is called when the orange button is pressed (GPIO 10 of the
141 * SuperIO chip, which maps to logical IRQ 26). If the press_count is 0,
142 * this is the first press, so it starts a timer and increments the counter.
143 * If it is higher than 0, it deletes the old timer, starts a new one, and
144 * increments the counter.
145 */
146
David Howells7d12e782006-10-05 14:55:46 +0100147static irqreturn_t button_handler (int irq, void *dev_id)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148{
149 if (button_press_count) {
150 del_timer (&button_timer);
151 }
152 button_press_count++;
153 init_timer (&button_timer);
154 button_timer.function = button_sequence_finished;
155 button_timer.expires = (jiffies + bdelay);
156 add_timer (&button_timer);
157
158 return IRQ_HANDLED;
159}
160
161/*
162 * This function is called when a user space program attempts to read
163 * /dev/nwbutton. It puts the device to sleep on the wait queue until
164 * button_sequence_finished writes some data to the buffer and flushes
165 * the queue, at which point it writes the data out to the device and
166 * returns the number of characters it has written. This function is
167 * reentrant, so that many processes can be attempting to read from the
168 * device at any one time.
169 */
170
171static int button_read (struct file *filp, char __user *buffer,
172 size_t count, loff_t *ppos)
173{
174 interruptible_sleep_on (&button_wait_queue);
175 return (copy_to_user (buffer, &button_output_buffer, bcount))
176 ? -EFAULT : bcount;
177}
178
179/*
180 * This structure is the file operations structure, which specifies what
181 * callbacks functions the kernel should call when a user mode process
182 * attempts to perform these operations on the device.
183 */
184
Arjan van de Ven62322d22006-07-03 00:24:21 -0700185static const struct file_operations button_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 .owner = THIS_MODULE,
187 .read = button_read,
188};
189
190/*
191 * This structure is the misc device structure, which specifies the minor
192 * device number (158 in this case), the name of the device (for /proc/misc),
193 * and the address of the above file operations structure.
194 */
195
196static struct miscdevice button_misc_device = {
197 BUTTON_MINOR,
198 "nwbutton",
199 &button_fops,
200};
201
202/*
203 * This function is called to initialise the driver, either from misc.c at
204 * bootup if the driver is compiled into the kernel, or from init_module
205 * below at module insert time. It attempts to register the device node
206 * and the IRQ and fails with a warning message if either fails, though
207 * neither ever should because the device number and IRQ are unique to
208 * this driver.
209 */
210
211static int __init nwbutton_init(void)
212{
213 if (!machine_is_netwinder())
214 return -ENODEV;
215
216 printk (KERN_INFO "NetWinder Button Driver Version %s (C) Alex Holden "
217 "<alex@linuxhacker.org> 1998.\n", VERSION);
218
219 if (misc_register (&button_misc_device)) {
220 printk (KERN_WARNING "nwbutton: Couldn't register device 10, "
221 "%d.\n", BUTTON_MINOR);
222 return -EBUSY;
223 }
224
Thomas Gleixner0f2ed4c2006-07-01 19:29:33 -0700225 if (request_irq (IRQ_NETWINDER_BUTTON, button_handler, IRQF_DISABLED,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 "nwbutton", NULL)) {
227 printk (KERN_WARNING "nwbutton: IRQ %d is not free.\n",
228 IRQ_NETWINDER_BUTTON);
229 misc_deregister (&button_misc_device);
230 return -EIO;
231 }
232 return 0;
233}
234
235static void __exit nwbutton_exit (void)
236{
237 free_irq (IRQ_NETWINDER_BUTTON, NULL);
238 misc_deregister (&button_misc_device);
239}
240
241
242MODULE_AUTHOR("Alex Holden");
243MODULE_LICENSE("GPL");
244
245module_init(nwbutton_init);
246module_exit(nwbutton_exit);