d21c95c569
This documents the fact that somebody looked at the relevant open() functions and concluded that, due to their trivial nature, no locking was needed. Signed-off-by: Jonathan Corbet <corbet@lwn.net>
133 lines
3.1 KiB
C
133 lines
3.1 KiB
C
/* linux/drivers/char/scx200_gpio.c
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National Semiconductor SCx200 GPIO driver. Allows a user space
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process to play with the GPIO pins.
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Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> */
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#include <linux/device.h>
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#include <linux/fs.h>
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <asm/uaccess.h>
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#include <asm/io.h>
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#include <linux/types.h>
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#include <linux/cdev.h>
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#include <linux/scx200_gpio.h>
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#include <linux/nsc_gpio.h>
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#define DRVNAME "scx200_gpio"
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static struct platform_device *pdev;
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MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
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MODULE_DESCRIPTION("NatSemi/AMD SCx200 GPIO Pin Driver");
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MODULE_LICENSE("GPL");
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static int major = 0; /* default to dynamic major */
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module_param(major, int, 0);
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MODULE_PARM_DESC(major, "Major device number");
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#define MAX_PINS 32 /* 64 later, when known ok */
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struct nsc_gpio_ops scx200_gpio_ops = {
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.owner = THIS_MODULE,
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.gpio_config = scx200_gpio_configure,
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.gpio_dump = nsc_gpio_dump,
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.gpio_get = scx200_gpio_get,
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.gpio_set = scx200_gpio_set,
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.gpio_change = scx200_gpio_change,
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.gpio_current = scx200_gpio_current
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};
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EXPORT_SYMBOL_GPL(scx200_gpio_ops);
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/* No BKL needed here: no global resources used */
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static int scx200_gpio_open(struct inode *inode, struct file *file)
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{
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unsigned m = iminor(inode);
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file->private_data = &scx200_gpio_ops;
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if (m >= MAX_PINS)
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return -EINVAL;
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return nonseekable_open(inode, file);
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}
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static int scx200_gpio_release(struct inode *inode, struct file *file)
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{
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return 0;
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}
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static const struct file_operations scx200_gpio_fileops = {
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.owner = THIS_MODULE,
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.write = nsc_gpio_write,
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.read = nsc_gpio_read,
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.open = scx200_gpio_open,
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.release = scx200_gpio_release,
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};
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static struct cdev scx200_gpio_cdev; /* use 1 cdev for all pins */
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static int __init scx200_gpio_init(void)
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{
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int rc;
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dev_t devid;
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if (!scx200_gpio_present()) {
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printk(KERN_ERR DRVNAME ": no SCx200 gpio present\n");
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return -ENODEV;
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}
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/* support dev_dbg() with pdev->dev */
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pdev = platform_device_alloc(DRVNAME, 0);
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if (!pdev)
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return -ENOMEM;
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rc = platform_device_add(pdev);
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if (rc)
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goto undo_malloc;
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/* nsc_gpio uses dev_dbg(), so needs this */
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scx200_gpio_ops.dev = &pdev->dev;
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if (major) {
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devid = MKDEV(major, 0);
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rc = register_chrdev_region(devid, MAX_PINS, "scx200_gpio");
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} else {
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rc = alloc_chrdev_region(&devid, 0, MAX_PINS, "scx200_gpio");
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major = MAJOR(devid);
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}
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if (rc < 0) {
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dev_err(&pdev->dev, "SCx200 chrdev_region err: %d\n", rc);
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goto undo_platform_device_add;
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}
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cdev_init(&scx200_gpio_cdev, &scx200_gpio_fileops);
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cdev_add(&scx200_gpio_cdev, devid, MAX_PINS);
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return 0; /* succeed */
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undo_platform_device_add:
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platform_device_del(pdev);
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undo_malloc:
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platform_device_put(pdev);
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return rc;
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}
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static void __exit scx200_gpio_cleanup(void)
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{
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cdev_del(&scx200_gpio_cdev);
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/* cdev_put(&scx200_gpio_cdev); */
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unregister_chrdev_region(MKDEV(major, 0), MAX_PINS);
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platform_device_unregister(pdev);
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}
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module_init(scx200_gpio_init);
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module_exit(scx200_gpio_cleanup);
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