f2b9857eee
All of the open() functions which don't need the BKL on their face may still depend on its acquisition to serialize opens against driver initialization. So make those functions acquire then release the BKL to be on the safe side. Signed-off-by: Jonathan Corbet <corbet@lwn.net>
134 lines
3.1 KiB
C
134 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 <linux/smp_lock.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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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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cycle_kernel_lock();
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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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