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1da177e4 LT |
1 | /* |
2 | * NetWinder Button Driver- | |
3 | * Copyright (C) Alex Holden <alex@linuxhacker.org> 1998, 1999. | |
4 | * | |
5 | */ | |
6 | ||
1da177e4 LT |
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> | |
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 | ||
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 */ | |
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 | ||
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 | } | |
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 | ||
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 | } | |
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 | ||
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 | } | |
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 | ||
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 | } | |
139 | ||
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 | */ | |
147 | ||
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); | |
158 | ||
159 | return IRQ_HANDLED; | |
160 | } | |
161 | ||
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 | */ | |
171 | ||
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 | } | |
179 | ||
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 | */ | |
185 | ||
62322d25 | 186 | static const struct file_operations button_fops = { |
1da177e4 LT |
187 | .owner = THIS_MODULE, |
188 | .read = button_read, | |
189 | }; | |
190 | ||
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 | */ | |
196 | ||
197 | static struct miscdevice button_misc_device = { | |
198 | BUTTON_MINOR, | |
199 | "nwbutton", | |
200 | &button_fops, | |
201 | }; | |
202 | ||
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 | */ | |
211 | ||
212 | static int __init nwbutton_init(void) | |
213 | { | |
214 | if (!machine_is_netwinder()) | |
215 | return -ENODEV; | |
216 | ||
217 | printk (KERN_INFO "NetWinder Button Driver Version %s (C) Alex Holden " | |
218 | "<alex@linuxhacker.org> 1998.\n", VERSION); | |
219 | ||
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 | } | |
225 | ||
0f2ed4c6 | 226 | if (request_irq (IRQ_NETWINDER_BUTTON, button_handler, IRQF_DISABLED, |
1da177e4 LT |
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 | } | |
235 | ||
236 | static void __exit nwbutton_exit (void) | |
237 | { | |
238 | free_irq (IRQ_NETWINDER_BUTTON, NULL); | |
239 | misc_deregister (&button_misc_device); | |
240 | } | |
241 | ||
242 | ||
243 | MODULE_AUTHOR("Alex Holden"); | |
244 | MODULE_LICENSE("GPL"); | |
245 | ||
246 | module_init(nwbutton_init); | |
247 | module_exit(nwbutton_exit); |