On Sat, 17 Jun 2006 12:34:37 -0600
Jim Cromie <[email protected]> wrote:
> --- ax-12/drivers/char/pc8736x_gpio.c 1969-12-31 17:00:00.000000000 -0700
> +++ ax-13/drivers/char/pc8736x_gpio.c 2006-06-17 01:39:58.000000000 -0600
> @@ -0,0 +1,295 @@
> +/* linux/drivers/char/pc8736x_gpio.c
> +
> + National Semiconductor PC8736x GPIO driver. Allows a user space
> + process to play with the GPIO pins.
> +
> + Copyright (c) 2005 Jim Cromie <[email protected]>
> +
> + adapted from linux/drivers/char/scx200_gpio.c
> + Copyright (c) 2001,2002 Christer Weinigel <[email protected]>,
> +*/
> +
> +#include <linux/config.h>
> +#include <linux/fs.h>
> +#include <linux/module.h>
> +#include <linux/errno.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/ioport.h>
> +#include <linux/nsc_gpio.h>
> +#include <asm/uaccess.h>
> +#include <asm/io.h>
New code should use linux/io.h and linux/uaccess.h. It won't matter in
this case, but you might pick up some goodies in the future.
> +#define NAME "pc8736x_gpio"
> +
> +MODULE_AUTHOR("Jim Cromie <[email protected]>");
> +MODULE_DESCRIPTION("NatSemi SCx200 GPIO Pin Driver");
> +MODULE_LICENSE("GPL");
> +
> +static int major = 0; /* default to dynamic major */
Unneeded initialisation.
> +static int pc8736x_superio_present(void)
> + /* try the 2 possible values, read a hardware reg to verify */
> +{
weird comment placement.
> +extern void nsc_gpio_dump(unsigned iminor);
Goes in a .h file.
> +static int __init pc8736x_gpio_init(void)
> +{
> + int r, rc;
> +
> + printk(KERN_DEBUG NAME " initializing\n");
> +
> + if (!pc8736x_superio_present()) {
> + printk(KERN_ERR NAME ": no device found\n");
> + return -ENODEV;
> + }
> +
> + /* Verify that chip and it's GPIO unit are both enabled.
> + My BIOS does this, so I take minimum action here
> + */
> + rc = superio_inb(SIO_CF1);
> + if (!(rc & 0x01)) {
> + printk(KERN_ERR NAME ": device not enabled\n");
> + return -ENODEV;
> + }
> + device_select(SIO_GPIO_UNIT);
> + if (!superio_inb(SIO_UNIT_ACT)) {
> + printk(KERN_ERR NAME ": GPIO unit not enabled\n");
> + return -ENODEV;
> + }
> +
> + /* read GPIO unit base address */
> + pc8736x_gpio_base = (superio_inb(SIO_BASE_HADDR) << 8
> + | superio_inb(SIO_BASE_LADDR));
> +
> + if (request_region(pc8736x_gpio_base, 16, NAME))
> + printk(KERN_INFO NAME ": GPIO ioport %x reserved\n",
> + pc8736x_gpio_base);
Isn't this fatal? If this IO region is in use by some other device, we
don't want this driver poking at it?
> + r = register_chrdev(major, NAME, &pc8736x_gpio_fops);
> + if (r < 0) {
> + printk(KERN_ERR NAME ": unable to register character device\n");
> + return r;
release_region()?
undo that device_select()?
> + }
> + if (!major) {
> + major = r;
> + printk(KERN_DEBUG NAME ": got dynamic major %d\n", major);
> + }
> +
> + return 0;
> +}
> +
> +static void __exit pc8736x_gpio_cleanup(void)
> +{
> + printk(KERN_DEBUG NAME " cleanup\n");
> +
> + release_region(pc8736x_gpio_base, 16);
> +
> + unregister_chrdev(major, NAME);
> +}
No need to shut down any hardware here?
-
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