linux/drivers/char/nsc_gpio.c
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   1/* linux/drivers/char/nsc_gpio.c
   2
   3   National Semiconductor common GPIO device-file/VFS methods.
   4   Allows a user space process to control the GPIO pins.
   5
   6   Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
   7   Copyright (c) 2005      Jim Cromie <jim.cromie@gmail.com>
   8*/
   9
  10#include <linux/fs.h>
  11#include <linux/module.h>
  12#include <linux/errno.h>
  13#include <linux/kernel.h>
  14#include <linux/init.h>
  15#include <linux/nsc_gpio.h>
  16#include <linux/platform_device.h>
  17#include <asm/uaccess.h>
  18#include <asm/io.h>
  19
  20#define NAME "nsc_gpio"
  21
  22void nsc_gpio_dump(struct nsc_gpio_ops *amp, unsigned index)
  23{
  24        /* retrieve current config w/o changing it */
  25        u32 config = amp->gpio_config(index, ~0, 0);
  26
  27        /* user requested via 'v' command, so its INFO */
  28        dev_info(amp->dev, "io%02u: 0x%04x %s %s %s %s %s %s %s\tio:%d/%d\n",
  29                 index, config,
  30                 (config & 1) ? "OE" : "TS",      /* output-enabled/tristate */
  31                 (config & 2) ? "PP" : "OD",      /* push pull / open drain */
  32                 (config & 4) ? "PUE" : "PUD",    /* pull up enabled/disabled */
  33                 (config & 8) ? "LOCKED" : "",    /* locked / unlocked */
  34                 (config & 16) ? "LEVEL" : "EDGE",/* level/edge input */
  35                 (config & 32) ? "HI" : "LO",     /* trigger on rise/fall edge */
  36                 (config & 64) ? "DEBOUNCE" : "", /* debounce */
  37
  38                 amp->gpio_get(index), amp->gpio_current(index));
  39}
  40
  41ssize_t nsc_gpio_write(struct file *file, const char __user *data,
  42                       size_t len, loff_t *ppos)
  43{
  44        unsigned m = iminor(file->f_path.dentry->d_inode);
  45        struct nsc_gpio_ops *amp = file->private_data;
  46        struct device *dev = amp->dev;
  47        size_t i;
  48        int err = 0;
  49
  50        for (i = 0; i < len; ++i) {
  51                char c;
  52                if (get_user(c, data + i))
  53                        return -EFAULT;
  54                switch (c) {
  55                case '0':
  56                        amp->gpio_set(m, 0);
  57                        break;
  58                case '1':
  59                        amp->gpio_set(m, 1);
  60                        break;
  61                case 'O':
  62                        dev_dbg(dev, "GPIO%d output enabled\n", m);
  63                        amp->gpio_config(m, ~1, 1);
  64                        break;
  65                case 'o':
  66                        dev_dbg(dev, "GPIO%d output disabled\n", m);
  67                        amp->gpio_config(m, ~1, 0);
  68                        break;
  69                case 'T':
  70                        dev_dbg(dev, "GPIO%d output is push pull\n", m);
  71                        amp->gpio_config(m, ~2, 2);
  72                        break;
  73                case 't':
  74                        dev_dbg(dev, "GPIO%d output is open drain\n", m);
  75                        amp->gpio_config(m, ~2, 0);
  76                        break;
  77                case 'P':
  78                        dev_dbg(dev, "GPIO%d pull up enabled\n", m);
  79                        amp->gpio_config(m, ~4, 4);
  80                        break;
  81                case 'p':
  82                        dev_dbg(dev, "GPIO%d pull up disabled\n", m);
  83                        amp->gpio_config(m, ~4, 0);
  84                        break;
  85                case 'v':
  86                        /* View Current pin settings */
  87                        amp->gpio_dump(amp, m);
  88                        break;
  89                case '\n':
  90                        /* end of settings string, do nothing */
  91                        break;
  92                default:
  93                        dev_err(dev, "io%2d bad setting: chr<0x%2x>\n",
  94                                m, (int)c);
  95                        err++;
  96                }
  97        }
  98        if (err)
  99                return -EINVAL; /* full string handled, report error */
 100
 101        return len;
 102}
 103
 104ssize_t nsc_gpio_read(struct file *file, char __user * buf,
 105                      size_t len, loff_t * ppos)
 106{
 107        unsigned m = iminor(file->f_path.dentry->d_inode);
 108        int value;
 109        struct nsc_gpio_ops *amp = file->private_data;
 110
 111        value = amp->gpio_get(m);
 112        if (put_user(value ? '1' : '0', buf))
 113                return -EFAULT;
 114
 115        return 1;
 116}
 117
 118/* common file-ops routines for both scx200_gpio and pc87360_gpio */
 119EXPORT_SYMBOL(nsc_gpio_write);
 120EXPORT_SYMBOL(nsc_gpio_read);
 121EXPORT_SYMBOL(nsc_gpio_dump);
 122
 123static int __init nsc_gpio_init(void)
 124{
 125        printk(KERN_DEBUG NAME " initializing\n");
 126        return 0;
 127}
 128
 129static void __exit nsc_gpio_cleanup(void)
 130{
 131        printk(KERN_DEBUG NAME " cleanup\n");
 132}
 133
 134module_init(nsc_gpio_init);
 135module_exit(nsc_gpio_cleanup);
 136
 137MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
 138MODULE_DESCRIPTION("NatSemi GPIO Common Methods");
 139MODULE_LICENSE("GPL");
 140
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