[linux.git] / drivers / char / nwbutton.c

/*
 * 	NetWinder Button Driver-
 *	Copyright (C) Alex Holden <[email protected]> 1998, 1999.
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/timer.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/init.h>

#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/mach-types.h>

#define __NWBUTTON_C		/* Tell the header file who we are */
#include "nwbutton.h"

static void button_sequence_finished (unsigned long parameters);

static int button_press_count;		/* The count of button presses */
/* Times for the end of a sequence */
static DEFINE_TIMER(button_timer, button_sequence_finished, 0, 0);
static DECLARE_WAIT_QUEUE_HEAD(button_wait_queue); /* Used for blocking read */
static char button_output_buffer[32];	/* Stores data to write out of device */
static int bcount;			/* The number of bytes in the buffer */
static int bdelay = BUTTON_DELAY;	/* The delay, in jiffies */
static struct button_callback button_callback_list[32]; /* The callback list */
static int callback_count;		/* The number of callbacks registered */
static int reboot_count = NUM_PRESSES_REBOOT; /* Number of presses to reboot */

/*
 * This function is called by other drivers to register a callback function
 * to be called when a particular number of button presses occurs.
 * The callback list is a static array of 32 entries (I somehow doubt many
 * people are ever going to want to register more than 32 different actions
 * to be performed by the kernel on different numbers of button presses ;).
 * However, if an attempt to register a 33rd entry (perhaps a stuck loop
 * somewhere registering the same entry over and over?) it will fail to
 * do so and return -ENOMEM. If an attempt is made to register a null pointer,
 * it will fail to do so and return -EINVAL.
 * Because callbacks can be unregistered at random the list can become
 * fragmented, so we need to search through the list until we find the first
 * free entry.
 *
 * FIXME: Has anyone spotted any locking functions int his code recently ??
 */

int button_add_callback (void (*callback) (void), int count)
{
	int lp = 0;
	if (callback_count == 32) {
		return -ENOMEM;
	}
	if (!callback) {
		return -EINVAL;
	}
	callback_count++;
	for (; (button_callback_list [lp].callback); lp++);
	button_callback_list [lp].callback = callback;
	button_callback_list [lp].count = count;
	return 0;
}

/*
 * This function is called by other drivers to deregister a callback function.
 * If you attempt to unregister a callback which does not exist, it will fail
 * with -EINVAL. If there is more than one entry with the same address,
 * because it searches the list from end to beginning, it will unregister the
 * last one to be registered first (FILO- First In Last Out).
 * Note that this is not necessarily true if the entries are not submitted
 * at the same time, because another driver could have unregistered a callback
 * between the submissions creating a gap earlier in the list, which would
 * be filled first at submission time.
 */

int button_del_callback (void (*callback) (void))
{
	int lp = 31;
	if (!callback) {
		return -EINVAL;
	}
	while (lp >= 0) {
		if ((button_callback_list [lp].callback) == callback) {
			button_callback_list [lp].callback = NULL;
			button_callback_list [lp].count = 0;
			callback_count--;
			return 0;
		}
		lp--;
	}
	return -EINVAL;
}

/*
 * This function is called by button_sequence_finished to search through the
 * list of callback functions, and call any of them whose count argument
 * matches the current count of button presses. It starts at the beginning
 * of the list and works up to the end. It will refuse to follow a null
 * pointer (which should never happen anyway).
 */

static void button_consume_callbacks (int bpcount)
{
	int lp = 0;
	for (; lp <= 31; lp++) {
		if ((button_callback_list [lp].count) == bpcount) {
			if (button_callback_list [lp].callback) {
				button_callback_list[lp].callback();
			}
		}
	}
}

/* 
 * This function is called when the button_timer times out.
 * ie. When you don't press the button for bdelay jiffies, this is taken to
 * mean you have ended the sequence of key presses, and this function is
 * called to wind things up (write the press_count out to /dev/button, call
 * any matching registered function callbacks, initiate reboot, etc.).
 */

static void button_sequence_finished (unsigned long parameters)
{
#ifdef CONFIG_NWBUTTON_REBOOT		/* Reboot using button is enabled */
	if (button_press_count == reboot_count)
		kill_cad_pid(SIGINT, 1);	/* Ask init to reboot us */
#endif /* CONFIG_NWBUTTON_REBOOT */
	button_consume_callbacks (button_press_count);
	bcount = sprintf (button_output_buffer, "%d\n", button_press_count);
	button_press_count = 0;		/* Reset the button press counter */
	wake_up_interruptible (&button_wait_queue);
}

/* 
 *  This handler is called when the orange button is pressed (GPIO 10 of the
 *  SuperIO chip, which maps to logical IRQ 26). If the press_count is 0,
 *  this is the first press, so it starts a timer and increments the counter.
 *  If it is higher than 0, it deletes the old timer, starts a new one, and
 *  increments the counter.
 */ 

static irqreturn_t button_handler (int irq, void *dev_id)
{
	button_press_count++;
	mod_timer(&button_timer, jiffies + bdelay);

	return IRQ_HANDLED;
}

/*
 * This function is called when a user space program attempts to read
 * /dev/nwbutton. It puts the device to sleep on the wait queue until
 * button_sequence_finished writes some data to the buffer and flushes
 * the queue, at which point it writes the data out to the device and
 * returns the number of characters it has written. This function is
 * reentrant, so that many processes can be attempting to read from the
 * device at any one time.
 */

static int button_read (struct file *filp, char __user *buffer,
			size_t count, loff_t *ppos)
{
	DEFINE_WAIT(wait);
	prepare_to_wait(&button_wait_queue, &wait, TASK_INTERRUPTIBLE);
	schedule();
	finish_wait(&button_wait_queue, &wait);
	return (copy_to_user (buffer, &button_output_buffer, bcount))
		 ? -EFAULT : bcount;
}

/* 
 * This structure is the file operations structure, which specifies what
 * callbacks functions the kernel should call when a user mode process
 * attempts to perform these operations on the device.
 */

static const struct file_operations button_fops = {
	.owner		= THIS_MODULE,
	.read		= button_read,
	.llseek		= noop_llseek,
};

/* 
 * This structure is the misc device structure, which specifies the minor
 * device number (158 in this case), the name of the device (for /proc/misc),
 * and the address of the above file operations structure.
 */

static struct miscdevice button_misc_device = {
	BUTTON_MINOR,
	"nwbutton",
	&button_fops,
};

/*
 * This function is called to initialise the driver, either from misc.c at
 * bootup if the driver is compiled into the kernel, or from init_module
 * below at module insert time. It attempts to register the device node
 * and the IRQ and fails with a warning message if either fails, though
 * neither ever should because the device number and IRQ are unique to
 * this driver.
 */

static int __init nwbutton_init(void)
{
	if (!machine_is_netwinder())
		return -ENODEV;

	printk (KERN_INFO "NetWinder Button Driver Version %s (C) Alex Holden "
			"<[email protected]> 1998.\n", VERSION);

	if (misc_register (&button_misc_device)) {
		printk (KERN_WARNING "nwbutton: Couldn't register device 10, "
				"%d.\n", BUTTON_MINOR);
		return -EBUSY;
	}

	if (request_irq (IRQ_NETWINDER_BUTTON, button_handler, 0,
			"nwbutton", NULL)) {
		printk (KERN_WARNING "nwbutton: IRQ %d is not free.\n",
				IRQ_NETWINDER_BUTTON);
		misc_deregister (&button_misc_device);
		return -EIO;
	}
	return 0;
}

static void __exit nwbutton_exit (void) 
{
	free_irq (IRQ_NETWINDER_BUTTON, NULL);
	misc_deregister (&button_misc_device);
}


MODULE_AUTHOR("Alex Holden");
MODULE_LICENSE("GPL");

module_init(nwbutton_init);
module_exit(nwbutton_exit);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* NetWinder Button Driver-
	3	* Copyright (C) Alex Holden <[email protected]> 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
40565f19 JS	26	static void button_sequence_finished (unsigned long parameters);
40565f19 JS	27
1da177e4	28	static int button_press_count; /* The count of button presses */
40565f19 JS	29	/* Times for the end of a sequence */
40565f19 JS	30	static DEFINE_TIMER(button_timer, button_sequence_finished, 0, 0);
1da177e4 LT	31	static DECLARE_WAIT_QUEUE_HEAD(button_wait_queue); /* Used for blocking read */
	32	static char button_output_buffer[32]; /* Stores data to write out of device */
	33	static int bcount; /* The number of bytes in the buffer */
	34	static int bdelay = BUTTON_DELAY; /* The delay, in jiffies */
	35	static struct button_callback button_callback_list[32]; /* The callback list */
	36	static int callback_count; /* The number of callbacks registered */
	37	static int reboot_count = NUM_PRESSES_REBOOT; /* Number of presses to reboot */
	38
	39	/*
	40	* This function is called by other drivers to register a callback function
	41	* to be called when a particular number of button presses occurs.
	42	* The callback list is a static array of 32 entries (I somehow doubt many
	43	* people are ever going to want to register more than 32 different actions
	44	* to be performed by the kernel on different numbers of button presses ;).
	45	* However, if an attempt to register a 33rd entry (perhaps a stuck loop
	46	* somewhere registering the same entry over and over?) it will fail to
	47	* do so and return -ENOMEM. If an attempt is made to register a null pointer,
	48	* it will fail to do so and return -EINVAL.
	49	* Because callbacks can be unregistered at random the list can become
	50	* fragmented, so we need to search through the list until we find the first
	51	* free entry.
	52	*
	53	* FIXME: Has anyone spotted any locking functions int his code recently ??
	54	*/
	55
	56	int button_add_callback (void (*callback) (void), int count)
	57	{
	58	int lp = 0;
	59	if (callback_count == 32) {
	60	return -ENOMEM;
	61	}
	62	if (!callback) {
	63	return -EINVAL;
	64	}
	65	callback_count++;
	66	for (; (button_callback_list [lp].callback); lp++);
	67	button_callback_list [lp].callback = callback;
	68	button_callback_list [lp].count = count;
	69	return 0;
	70	}
	71
	72	/*
	73	* This function is called by other drivers to deregister a callback function.
	74	* If you attempt to unregister a callback which does not exist, it will fail
	75	* with -EINVAL. If there is more than one entry with the same address,
	76	* because it searches the list from end to beginning, it will unregister the
	77	* last one to be registered first (FILO- First In Last Out).
25985edc	78	* Note that this is not necessarily true if the entries are not submitted
1da177e4 LT	79	* at the same time, because another driver could have unregistered a callback
	80	* between the submissions creating a gap earlier in the list, which would
	81	* be filled first at submission time.
	82	*/
	83
	84	int button_del_callback (void (*callback) (void))
	85	{
	86	int lp = 31;
	87	if (!callback) {
	88	return -EINVAL;
	89	}
	90	while (lp >= 0) {
	91	if ((button_callback_list [lp].callback) == callback) {
	92	button_callback_list [lp].callback = NULL;
	93	button_callback_list [lp].count = 0;
	94	callback_count--;
	95	return 0;
f8885c26	96	}
1da177e4	97	lp--;
f8885c26	98	}
1da177e4 LT	99	return -EINVAL;
	100	}
	101
	102	/*
	103	* This function is called by button_sequence_finished to search through the
	104	* list of callback functions, and call any of them whose count argument
	105	* matches the current count of button presses. It starts at the beginning
	106	* of the list and works up to the end. It will refuse to follow a null
	107	* pointer (which should never happen anyway).
	108	*/
	109
	110	static void button_consume_callbacks (int bpcount)
	111	{
	112	int lp = 0;
	113	for (; lp <= 31; lp++) {
	114	if ((button_callback_list [lp].count) == bpcount) {
	115	if (button_callback_list [lp].callback) {
	116	button_callback_list[lp].callback();
	117	}
	118	}
	119	}
	120	}
	121
	122	/*
	123	* This function is called when the button_timer times out.
	124	* ie. When you don't press the button for bdelay jiffies, this is taken to
	125	* mean you have ended the sequence of key presses, and this function is
	126	* called to wind things up (write the press_count out to /dev/button, call
	127	* any matching registered function callbacks, initiate reboot, etc.).
	128	*/
	129
	130	static void button_sequence_finished (unsigned long parameters)
	131	{
	132	#ifdef CONFIG_NWBUTTON_REBOOT /* Reboot using button is enabled */
9ec52099 CLG	133	if (button_press_count == reboot_count)
9ec52099 CLG	134	kill_cad_pid(SIGINT, 1); /* Ask init to reboot us */
1da177e4 LT	135	#endif /* CONFIG_NWBUTTON_REBOOT */
	136	button_consume_callbacks (button_press_count);
	137	bcount = sprintf (button_output_buffer, "%d\n", button_press_count);
	138	button_press_count = 0; /* Reset the button press counter */
	139	wake_up_interruptible (&button_wait_queue);
	140	}
	141
	142	/*
	143	* This handler is called when the orange button is pressed (GPIO 10 of the
	144	* SuperIO chip, which maps to logical IRQ 26). If the press_count is 0,
	145	* this is the first press, so it starts a timer and increments the counter.
	146	* If it is higher than 0, it deletes the old timer, starts a new one, and
	147	* increments the counter.
	148	*/
	149
7d12e780	150	static irqreturn_t button_handler (int irq, void *dev_id)
1da177e4	151	{
1da177e4	152	button_press_count++;
40565f19	153	mod_timer(&button_timer, jiffies + bdelay);
1da177e4 LT	154
	155	return IRQ_HANDLED;
	156	}
	157
	158	/*
	159	* This function is called when a user space program attempts to read
	160	* /dev/nwbutton. It puts the device to sleep on the wait queue until
	161	* button_sequence_finished writes some data to the buffer and flushes
	162	* the queue, at which point it writes the data out to the device and
	163	* returns the number of characters it has written. This function is
	164	* reentrant, so that many processes can be attempting to read from the
	165	* device at any one time.
	166	*/
	167
	168	static int button_read (struct file filp, char __user buffer,
	169	size_t count, loff_t *ppos)
	170	{
eb831743 AB	171	DEFINE_WAIT(wait);
	172	prepare_to_wait(&button_wait_queue, &wait, TASK_INTERRUPTIBLE);
	173	schedule();
	174	finish_wait(&button_wait_queue, &wait);
1da177e4 LT	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
62322d25	185	static const struct file_operations button_fops = {
1da177e4 LT	186	.owner = THIS_MODULE,
1da177e4 LT	187	.read = button_read,
6038f373	188	.llseek = noop_llseek,
1da177e4 LT	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	"<[email protected]> 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
d88ed628	226	if (request_irq (IRQ_NETWINDER_BUTTON, button_handler, 0,
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);