Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
This commit is contained in:
Linus Torvalds
248
drivers/char/nwbutton.c
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248
drivers/char/nwbutton.c
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/*
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* NetWinder Button Driver-
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* Copyright (C) Alex Holden <alex@linuxhacker.org> 1998, 1999.
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*
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/interrupt.h>
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#include <linux/time.h>
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#include <linux/timer.h>
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#include <linux/fs.h>
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#include <linux/miscdevice.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <asm/uaccess.h>
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#include <asm/irq.h>
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#include <asm/mach-types.h>
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#define __NWBUTTON_C /* Tell the header file who we are */
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#include "nwbutton.h"
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static int button_press_count; /* The count of button presses */
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static struct timer_list button_timer; /* Times for the end of a sequence */
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static DECLARE_WAIT_QUEUE_HEAD(button_wait_queue); /* Used for blocking read */
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static char button_output_buffer[32]; /* Stores data to write out of device */
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static int bcount; /* The number of bytes in the buffer */
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static int bdelay = BUTTON_DELAY; /* The delay, in jiffies */
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static struct button_callback button_callback_list[32]; /* The callback list */
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static int callback_count; /* The number of callbacks registered */
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static int reboot_count = NUM_PRESSES_REBOOT; /* Number of presses to reboot */
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/*
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* This function is called by other drivers to register a callback function
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* to be called when a particular number of button presses occurs.
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* The callback list is a static array of 32 entries (I somehow doubt many
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* people are ever going to want to register more than 32 different actions
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* to be performed by the kernel on different numbers of button presses ;).
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* However, if an attempt to register a 33rd entry (perhaps a stuck loop
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* somewhere registering the same entry over and over?) it will fail to
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* do so and return -ENOMEM. If an attempt is made to register a null pointer,
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* it will fail to do so and return -EINVAL.
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* Because callbacks can be unregistered at random the list can become
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* fragmented, so we need to search through the list until we find the first
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* free entry.
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*
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* FIXME: Has anyone spotted any locking functions int his code recently ??
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*/
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int button_add_callback (void (*callback) (void), int count)
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{
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int lp = 0;
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if (callback_count == 32) {
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return -ENOMEM;
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}
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if (!callback) {
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return -EINVAL;
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}
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callback_count++;
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for (; (button_callback_list [lp].callback); lp++);
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button_callback_list [lp].callback = callback;
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button_callback_list [lp].count = count;
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return 0;
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}
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/*
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* This function is called by other drivers to deregister a callback function.
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* If you attempt to unregister a callback which does not exist, it will fail
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* with -EINVAL. If there is more than one entry with the same address,
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* because it searches the list from end to beginning, it will unregister the
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* last one to be registered first (FILO- First In Last Out).
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* Note that this is not neccessarily true if the entries are not submitted
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* at the same time, because another driver could have unregistered a callback
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* between the submissions creating a gap earlier in the list, which would
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* be filled first at submission time.
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*/
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int button_del_callback (void (*callback) (void))
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{
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int lp = 31;
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if (!callback) {
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return -EINVAL;
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}
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while (lp >= 0) {
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if ((button_callback_list [lp].callback) == callback) {
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button_callback_list [lp].callback = NULL;
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button_callback_list [lp].count = 0;
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callback_count--;
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return 0;
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};
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lp--;
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};
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return -EINVAL;
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}
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/*
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* This function is called by button_sequence_finished to search through the
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* list of callback functions, and call any of them whose count argument
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* matches the current count of button presses. It starts at the beginning
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* of the list and works up to the end. It will refuse to follow a null
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* pointer (which should never happen anyway).
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*/
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static void button_consume_callbacks (int bpcount)
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{
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int lp = 0;
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for (; lp <= 31; lp++) {
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if ((button_callback_list [lp].count) == bpcount) {
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if (button_callback_list [lp].callback) {
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button_callback_list[lp].callback();
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}
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}
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}
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}
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/*
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* This function is called when the button_timer times out.
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* ie. When you don't press the button for bdelay jiffies, this is taken to
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* mean you have ended the sequence of key presses, and this function is
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* called to wind things up (write the press_count out to /dev/button, call
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* any matching registered function callbacks, initiate reboot, etc.).
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*/
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static void button_sequence_finished (unsigned long parameters)
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{
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#ifdef CONFIG_NWBUTTON_REBOOT /* Reboot using button is enabled */
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if (button_press_count == reboot_count) {
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kill_proc (1, SIGINT, 1); /* Ask init to reboot us */
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}
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#endif /* CONFIG_NWBUTTON_REBOOT */
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button_consume_callbacks (button_press_count);
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bcount = sprintf (button_output_buffer, "%d\n", button_press_count);
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button_press_count = 0; /* Reset the button press counter */
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wake_up_interruptible (&button_wait_queue);
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}
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/*
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* This handler is called when the orange button is pressed (GPIO 10 of the
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* SuperIO chip, which maps to logical IRQ 26). If the press_count is 0,
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* this is the first press, so it starts a timer and increments the counter.
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* If it is higher than 0, it deletes the old timer, starts a new one, and
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* increments the counter.
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*/
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static irqreturn_t button_handler (int irq, void *dev_id, struct pt_regs *regs)
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{
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if (button_press_count) {
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del_timer (&button_timer);
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}
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button_press_count++;
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init_timer (&button_timer);
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button_timer.function = button_sequence_finished;
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button_timer.expires = (jiffies + bdelay);
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add_timer (&button_timer);
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return IRQ_HANDLED;
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}
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/*
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* This function is called when a user space program attempts to read
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* /dev/nwbutton. It puts the device to sleep on the wait queue until
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* button_sequence_finished writes some data to the buffer and flushes
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* the queue, at which point it writes the data out to the device and
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* returns the number of characters it has written. This function is
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* reentrant, so that many processes can be attempting to read from the
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* device at any one time.
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*/
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static int button_read (struct file *filp, char __user *buffer,
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size_t count, loff_t *ppos)
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{
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interruptible_sleep_on (&button_wait_queue);
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return (copy_to_user (buffer, &button_output_buffer, bcount))
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? -EFAULT : bcount;
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}
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/*
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* This structure is the file operations structure, which specifies what
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* callbacks functions the kernel should call when a user mode process
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* attempts to perform these operations on the device.
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*/
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static struct file_operations button_fops = {
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.owner = THIS_MODULE,
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.read = button_read,
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};
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/*
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* This structure is the misc device structure, which specifies the minor
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* device number (158 in this case), the name of the device (for /proc/misc),
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* and the address of the above file operations structure.
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*/
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static struct miscdevice button_misc_device = {
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BUTTON_MINOR,
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"nwbutton",
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&button_fops,
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};
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/*
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* This function is called to initialise the driver, either from misc.c at
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* bootup if the driver is compiled into the kernel, or from init_module
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* below at module insert time. It attempts to register the device node
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* and the IRQ and fails with a warning message if either fails, though
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* neither ever should because the device number and IRQ are unique to
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* this driver.
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*/
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static int __init nwbutton_init(void)
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{
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if (!machine_is_netwinder())
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return -ENODEV;
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printk (KERN_INFO "NetWinder Button Driver Version %s (C) Alex Holden "
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"<alex@linuxhacker.org> 1998.\n", VERSION);
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if (misc_register (&button_misc_device)) {
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printk (KERN_WARNING "nwbutton: Couldn't register device 10, "
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"%d.\n", BUTTON_MINOR);
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return -EBUSY;
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}
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if (request_irq (IRQ_NETWINDER_BUTTON, button_handler, SA_INTERRUPT,
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"nwbutton", NULL)) {
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printk (KERN_WARNING "nwbutton: IRQ %d is not free.\n",
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IRQ_NETWINDER_BUTTON);
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misc_deregister (&button_misc_device);
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return -EIO;
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}
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return 0;
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}
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static void __exit nwbutton_exit (void)
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{
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free_irq (IRQ_NETWINDER_BUTTON, NULL);
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misc_deregister (&button_misc_device);
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}
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MODULE_AUTHOR("Alex Holden");
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MODULE_LICENSE("GPL");
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module_init(nwbutton_init);
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module_exit(nwbutton_exit);
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