ia64/linux-2.6.18-xen.hg

view drivers/char/nwbutton.c @ 893:f994bfe9b93b

linux/blktap2: reduce TLB flush scope

c/s 885 added very coarse TLB flushing. Since these flushes always
follow single page updates, single page flushes (when available) are
sufficient.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
author Keir Fraser <keir.fraser@citrix.com>
date Thu Jun 04 10:32:57 2009 +0100 (2009-06-04)
parents 831230e53067
children
line source
1 /*
2 * NetWinder Button Driver-
3 * Copyright (C) Alex Holden <alex@linuxhacker.org> 1998, 1999.
4 *
5 */
7 #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>
19 #include <asm/uaccess.h>
20 #include <asm/irq.h>
21 #include <asm/mach-types.h>
23 #define __NWBUTTON_C /* Tell the header file who we are */
24 #include "nwbutton.h"
26 static int button_press_count; /* The count of button presses */
27 static struct timer_list button_timer; /* Times for the end of a sequence */
28 static DECLARE_WAIT_QUEUE_HEAD(button_wait_queue); /* Used for blocking read */
29 static char button_output_buffer[32]; /* Stores data to write out of device */
30 static int bcount; /* The number of bytes in the buffer */
31 static int bdelay = BUTTON_DELAY; /* The delay, in jiffies */
32 static struct button_callback button_callback_list[32]; /* The callback list */
33 static int callback_count; /* The number of callbacks registered */
34 static int reboot_count = NUM_PRESSES_REBOOT; /* Number of presses to reboot */
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 */
53 int 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 }
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 */
81 int 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 }
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 */
107 static 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 }
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 */
127 static void button_sequence_finished (unsigned long parameters)
128 {
129 #ifdef CONFIG_NWBUTTON_REBOOT /* Reboot using button is enabled */
130 if (button_press_count == reboot_count) {
131 kill_proc (1, SIGINT, 1); /* Ask init to reboot us */
132 }
133 #endif /* CONFIG_NWBUTTON_REBOOT */
134 button_consume_callbacks (button_press_count);
135 bcount = sprintf (button_output_buffer, "%d\n", button_press_count);
136 button_press_count = 0; /* Reset the button press counter */
137 wake_up_interruptible (&button_wait_queue);
138 }
140 /*
141 * This handler is called when the orange button is pressed (GPIO 10 of the
142 * SuperIO chip, which maps to logical IRQ 26). If the press_count is 0,
143 * this is the first press, so it starts a timer and increments the counter.
144 * If it is higher than 0, it deletes the old timer, starts a new one, and
145 * increments the counter.
146 */
148 static irqreturn_t button_handler (int irq, void *dev_id, struct pt_regs *regs)
149 {
150 if (button_press_count) {
151 del_timer (&button_timer);
152 }
153 button_press_count++;
154 init_timer (&button_timer);
155 button_timer.function = button_sequence_finished;
156 button_timer.expires = (jiffies + bdelay);
157 add_timer (&button_timer);
159 return IRQ_HANDLED;
160 }
162 /*
163 * This function is called when a user space program attempts to read
164 * /dev/nwbutton. It puts the device to sleep on the wait queue until
165 * button_sequence_finished writes some data to the buffer and flushes
166 * the queue, at which point it writes the data out to the device and
167 * returns the number of characters it has written. This function is
168 * reentrant, so that many processes can be attempting to read from the
169 * device at any one time.
170 */
172 static int button_read (struct file *filp, char __user *buffer,
173 size_t count, loff_t *ppos)
174 {
175 interruptible_sleep_on (&button_wait_queue);
176 return (copy_to_user (buffer, &button_output_buffer, bcount))
177 ? -EFAULT : bcount;
178 }
180 /*
181 * This structure is the file operations structure, which specifies what
182 * callbacks functions the kernel should call when a user mode process
183 * attempts to perform these operations on the device.
184 */
186 static const struct file_operations button_fops = {
187 .owner = THIS_MODULE,
188 .read = button_read,
189 };
191 /*
192 * This structure is the misc device structure, which specifies the minor
193 * device number (158 in this case), the name of the device (for /proc/misc),
194 * and the address of the above file operations structure.
195 */
197 static struct miscdevice button_misc_device = {
198 BUTTON_MINOR,
199 "nwbutton",
200 &button_fops,
201 };
203 /*
204 * This function is called to initialise the driver, either from misc.c at
205 * bootup if the driver is compiled into the kernel, or from init_module
206 * below at module insert time. It attempts to register the device node
207 * and the IRQ and fails with a warning message if either fails, though
208 * neither ever should because the device number and IRQ are unique to
209 * this driver.
210 */
212 static int __init nwbutton_init(void)
213 {
214 if (!machine_is_netwinder())
215 return -ENODEV;
217 printk (KERN_INFO "NetWinder Button Driver Version %s (C) Alex Holden "
218 "<alex@linuxhacker.org> 1998.\n", VERSION);
220 if (misc_register (&button_misc_device)) {
221 printk (KERN_WARNING "nwbutton: Couldn't register device 10, "
222 "%d.\n", BUTTON_MINOR);
223 return -EBUSY;
224 }
226 if (request_irq (IRQ_NETWINDER_BUTTON, button_handler, IRQF_DISABLED,
227 "nwbutton", NULL)) {
228 printk (KERN_WARNING "nwbutton: IRQ %d is not free.\n",
229 IRQ_NETWINDER_BUTTON);
230 misc_deregister (&button_misc_device);
231 return -EIO;
232 }
233 return 0;
234 }
236 static void __exit nwbutton_exit (void)
237 {
238 free_irq (IRQ_NETWINDER_BUTTON, NULL);
239 misc_deregister (&button_misc_device);
240 }
243 MODULE_AUTHOR("Alex Holden");
244 MODULE_LICENSE("GPL");
246 module_init(nwbutton_init);
247 module_exit(nwbutton_exit);