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1da177e4 LT |
1 | /* |
2 | * NetWinder Button Driver- | |
3 | * Copyright (C) Alex Holden <alex@linuxhacker.org> 1998, 1999. | |
4 | * | |
5 | */ | |
6 | ||
7 | #include <linux/config.h> | |
8 | #include <linux/module.h> | |
9 | #include <linux/kernel.h> | |
10 | #include <linux/sched.h> | |
11 | #include <linux/interrupt.h> | |
12 | #include <linux/time.h> | |
13 | #include <linux/timer.h> | |
14 | #include <linux/fs.h> | |
15 | #include <linux/miscdevice.h> | |
16 | #include <linux/string.h> | |
17 | #include <linux/errno.h> | |
18 | #include <linux/init.h> | |
19 | ||
20 | #include <asm/uaccess.h> | |
21 | #include <asm/irq.h> | |
22 | #include <asm/mach-types.h> | |
23 | ||
24 | #define __NWBUTTON_C /* Tell the header file who we are */ | |
25 | #include "nwbutton.h" | |
26 | ||
27 | static int button_press_count; /* The count of button presses */ | |
28 | static struct timer_list button_timer; /* Times for the end of a sequence */ | |
29 | static DECLARE_WAIT_QUEUE_HEAD(button_wait_queue); /* Used for blocking read */ | |
30 | static char button_output_buffer[32]; /* Stores data to write out of device */ | |
31 | static int bcount; /* The number of bytes in the buffer */ | |
32 | static int bdelay = BUTTON_DELAY; /* The delay, in jiffies */ | |
33 | static struct button_callback button_callback_list[32]; /* The callback list */ | |
34 | static int callback_count; /* The number of callbacks registered */ | |
35 | static int reboot_count = NUM_PRESSES_REBOOT; /* Number of presses to reboot */ | |
36 | ||
37 | /* | |
38 | * This function is called by other drivers to register a callback function | |
39 | * to be called when a particular number of button presses occurs. | |
40 | * The callback list is a static array of 32 entries (I somehow doubt many | |
41 | * people are ever going to want to register more than 32 different actions | |
42 | * to be performed by the kernel on different numbers of button presses ;). | |
43 | * However, if an attempt to register a 33rd entry (perhaps a stuck loop | |
44 | * somewhere registering the same entry over and over?) it will fail to | |
45 | * do so and return -ENOMEM. If an attempt is made to register a null pointer, | |
46 | * it will fail to do so and return -EINVAL. | |
47 | * Because callbacks can be unregistered at random the list can become | |
48 | * fragmented, so we need to search through the list until we find the first | |
49 | * free entry. | |
50 | * | |
51 | * FIXME: Has anyone spotted any locking functions int his code recently ?? | |
52 | */ | |
53 | ||
54 | int button_add_callback (void (*callback) (void), int count) | |
55 | { | |
56 | int lp = 0; | |
57 | if (callback_count == 32) { | |
58 | return -ENOMEM; | |
59 | } | |
60 | if (!callback) { | |
61 | return -EINVAL; | |
62 | } | |
63 | callback_count++; | |
64 | for (; (button_callback_list [lp].callback); lp++); | |
65 | button_callback_list [lp].callback = callback; | |
66 | button_callback_list [lp].count = count; | |
67 | return 0; | |
68 | } | |
69 | ||
70 | /* | |
71 | * This function is called by other drivers to deregister a callback function. | |
72 | * If you attempt to unregister a callback which does not exist, it will fail | |
73 | * with -EINVAL. If there is more than one entry with the same address, | |
74 | * because it searches the list from end to beginning, it will unregister the | |
75 | * last one to be registered first (FILO- First In Last Out). | |
76 | * Note that this is not neccessarily true if the entries are not submitted | |
77 | * at the same time, because another driver could have unregistered a callback | |
78 | * between the submissions creating a gap earlier in the list, which would | |
79 | * be filled first at submission time. | |
80 | */ | |
81 | ||
82 | int button_del_callback (void (*callback) (void)) | |
83 | { | |
84 | int lp = 31; | |
85 | if (!callback) { | |
86 | return -EINVAL; | |
87 | } | |
88 | while (lp >= 0) { | |
89 | if ((button_callback_list [lp].callback) == callback) { | |
90 | button_callback_list [lp].callback = NULL; | |
91 | button_callback_list [lp].count = 0; | |
92 | callback_count--; | |
93 | return 0; | |
94 | }; | |
95 | lp--; | |
96 | }; | |
97 | return -EINVAL; | |
98 | } | |
99 | ||
100 | /* | |
101 | * This function is called by button_sequence_finished to search through the | |
102 | * list of callback functions, and call any of them whose count argument | |
103 | * matches the current count of button presses. It starts at the beginning | |
104 | * of the list and works up to the end. It will refuse to follow a null | |
105 | * pointer (which should never happen anyway). | |
106 | */ | |
107 | ||
108 | static void button_consume_callbacks (int bpcount) | |
109 | { | |
110 | int lp = 0; | |
111 | for (; lp <= 31; lp++) { | |
112 | if ((button_callback_list [lp].count) == bpcount) { | |
113 | if (button_callback_list [lp].callback) { | |
114 | button_callback_list[lp].callback(); | |
115 | } | |
116 | } | |
117 | } | |
118 | } | |
119 | ||
120 | /* | |
121 | * This function is called when the button_timer times out. | |
122 | * ie. When you don't press the button for bdelay jiffies, this is taken to | |
123 | * mean you have ended the sequence of key presses, and this function is | |
124 | * called to wind things up (write the press_count out to /dev/button, call | |
125 | * any matching registered function callbacks, initiate reboot, etc.). | |
126 | */ | |
127 | ||
128 | static void button_sequence_finished (unsigned long parameters) | |
129 | { | |
130 | #ifdef CONFIG_NWBUTTON_REBOOT /* Reboot using button is enabled */ | |
131 | if (button_press_count == reboot_count) { | |
132 | kill_proc (1, SIGINT, 1); /* Ask init to reboot us */ | |
133 | } | |
134 | #endif /* CONFIG_NWBUTTON_REBOOT */ | |
135 | button_consume_callbacks (button_press_count); | |
136 | bcount = sprintf (button_output_buffer, "%d\n", button_press_count); | |
137 | button_press_count = 0; /* Reset the button press counter */ | |
138 | wake_up_interruptible (&button_wait_queue); | |
139 | } | |
140 | ||
141 | /* | |
142 | * This handler is called when the orange button is pressed (GPIO 10 of the | |
143 | * SuperIO chip, which maps to logical IRQ 26). If the press_count is 0, | |
144 | * this is the first press, so it starts a timer and increments the counter. | |
145 | * If it is higher than 0, it deletes the old timer, starts a new one, and | |
146 | * increments the counter. | |
147 | */ | |
148 | ||
149 | static irqreturn_t button_handler (int irq, void *dev_id, struct pt_regs *regs) | |
150 | { | |
151 | if (button_press_count) { | |
152 | del_timer (&button_timer); | |
153 | } | |
154 | button_press_count++; | |
155 | init_timer (&button_timer); | |
156 | button_timer.function = button_sequence_finished; | |
157 | button_timer.expires = (jiffies + bdelay); | |
158 | add_timer (&button_timer); | |
159 | ||
160 | return IRQ_HANDLED; | |
161 | } | |
162 | ||
163 | /* | |
164 | * This function is called when a user space program attempts to read | |
165 | * /dev/nwbutton. It puts the device to sleep on the wait queue until | |
166 | * button_sequence_finished writes some data to the buffer and flushes | |
167 | * the queue, at which point it writes the data out to the device and | |
168 | * returns the number of characters it has written. This function is | |
169 | * reentrant, so that many processes can be attempting to read from the | |
170 | * device at any one time. | |
171 | */ | |
172 | ||
173 | static int button_read (struct file *filp, char __user *buffer, | |
174 | size_t count, loff_t *ppos) | |
175 | { | |
176 | interruptible_sleep_on (&button_wait_queue); | |
177 | return (copy_to_user (buffer, &button_output_buffer, bcount)) | |
178 | ? -EFAULT : bcount; | |
179 | } | |
180 | ||
181 | /* | |
182 | * This structure is the file operations structure, which specifies what | |
183 | * callbacks functions the kernel should call when a user mode process | |
184 | * attempts to perform these operations on the device. | |
185 | */ | |
186 | ||
187 | static struct file_operations button_fops = { | |
188 | .owner = THIS_MODULE, | |
189 | .read = button_read, | |
190 | }; | |
191 | ||
192 | /* | |
193 | * This structure is the misc device structure, which specifies the minor | |
194 | * device number (158 in this case), the name of the device (for /proc/misc), | |
195 | * and the address of the above file operations structure. | |
196 | */ | |
197 | ||
198 | static struct miscdevice button_misc_device = { | |
199 | BUTTON_MINOR, | |
200 | "nwbutton", | |
201 | &button_fops, | |
202 | }; | |
203 | ||
204 | /* | |
205 | * This function is called to initialise the driver, either from misc.c at | |
206 | * bootup if the driver is compiled into the kernel, or from init_module | |
207 | * below at module insert time. It attempts to register the device node | |
208 | * and the IRQ and fails with a warning message if either fails, though | |
209 | * neither ever should because the device number and IRQ are unique to | |
210 | * this driver. | |
211 | */ | |
212 | ||
213 | static int __init nwbutton_init(void) | |
214 | { | |
215 | if (!machine_is_netwinder()) | |
216 | return -ENODEV; | |
217 | ||
218 | printk (KERN_INFO "NetWinder Button Driver Version %s (C) Alex Holden " | |
219 | "<alex@linuxhacker.org> 1998.\n", VERSION); | |
220 | ||
221 | if (misc_register (&button_misc_device)) { | |
222 | printk (KERN_WARNING "nwbutton: Couldn't register device 10, " | |
223 | "%d.\n", BUTTON_MINOR); | |
224 | return -EBUSY; | |
225 | } | |
226 | ||
227 | if (request_irq (IRQ_NETWINDER_BUTTON, button_handler, SA_INTERRUPT, | |
228 | "nwbutton", NULL)) { | |
229 | printk (KERN_WARNING "nwbutton: IRQ %d is not free.\n", | |
230 | IRQ_NETWINDER_BUTTON); | |
231 | misc_deregister (&button_misc_device); | |
232 | return -EIO; | |
233 | } | |
234 | return 0; | |
235 | } | |
236 | ||
237 | static void __exit nwbutton_exit (void) | |
238 | { | |
239 | free_irq (IRQ_NETWINDER_BUTTON, NULL); | |
240 | misc_deregister (&button_misc_device); | |
241 | } | |
242 | ||
243 | ||
244 | MODULE_AUTHOR("Alex Holden"); | |
245 | MODULE_LICENSE("GPL"); | |
246 | ||
247 | module_init(nwbutton_init); | |
248 | module_exit(nwbutton_exit); |