drivers/char/nsc_gpio.c

   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/config.h>
  11 #include <linux/fs.h>
  12 #include <linux/module.h>
  13 #include <linux/errno.h>
  14 #include <linux/kernel.h>
  15 #include <linux/init.h>
  16 #include <linux/nsc_gpio.h>
  17 #include <asm/uaccess.h>
  18 #include <asm/io.h>
  19
  20 #define NAME "nsc_gpio"
  21
  22 void nsc_gpio_dump(unsigned index, u32 config)
  23 {
  24         printk(KERN_INFO NAME ": GPIO-%02u: 0x%08lx %s %s %s %s %s %s %s\n",
  25                index, (unsigned long)config,
  26                (config & 1) ? "OE" : "TS",      /* output-enabled/tristate */
  27                (config & 2) ? "PP" : "OD",      /* push pull / open drain */
  28                (config & 4) ? "PUE" : "PUD",    /* pull up enabled/disabled */
  29                (config & 8) ? "LOCKED" : "",    /* locked / unlocked */
  30                (config & 16) ? "LEVEL" : "EDGE",/* level/edge input */
  31                (config & 32) ? "HI" : "LO",     /* trigger on rise/fall edge */
  32                (config & 64) ? "DEBOUNCE" : "");        /* debounce */
  33 }
  34
  35 ssize_t nsc_gpio_write(struct file *file, const char __user *data,
  36                        size_t len, loff_t *ppos)
  37 {
  38         unsigned m = iminor(file->f_dentry->d_inode);
  39         struct nsc_gpio_ops *amp = file->private_data;
  40         size_t i;
  41         int err = 0;
  42
  43         for (i = 0; i < len; ++i) {
  44                 char c;
  45                 if (get_user(c, data + i))
  46                         return -EFAULT;
  47                 switch (c) {
  48                 case '0':
  49                         amp->gpio_set(m, 0);
  50                         break;
  51                 case '1':
  52                         amp->gpio_set(m, 1);
  53                         break;
  54                 case 'O':
  55                         printk(KERN_INFO NAME ": GPIO%d output enabled\n", m);
  56                         amp->gpio_config(m, ~1, 1);
  57                         break;
  58                 case 'o':
  59                         printk(KERN_INFO NAME ": GPIO%d output disabled\n", m);
  60                         amp->gpio_config(m, ~1, 0);
  61                         break;
  62                 case 'T':
  63                         printk(KERN_INFO NAME ": GPIO%d output is push pull\n",
  64                                m);
  65                         amp->gpio_config(m, ~2, 2);
  66                         break;
  67                 case 't':
  68                         printk(KERN_INFO NAME ": GPIO%d output is open drain\n",
  69                                m);
  70                         amp->gpio_config(m, ~2, 0);
  71                         break;
  72                 case 'P':
  73                         printk(KERN_INFO NAME ": GPIO%d pull up enabled\n", m);
  74                         amp->gpio_config(m, ~4, 4);
  75                         break;
  76                 case 'p':
  77                         printk(KERN_INFO NAME ": GPIO%d pull up disabled\n", m);
  78                         amp->gpio_config(m, ~4, 0);
  79                         break;
  80                 case 'v':
  81                         /* View Current pin settings */
  82                         amp->gpio_dump(m);
  83                         break;
  84                 case '\n':
  85                         /* end of settings string, do nothing */
  86                         break;
  87                 default:
  88                         printk(KERN_ERR NAME
  89                                ": GPIO-%2d bad setting: chr<0x%2x>\n", m,
  90                                (int)c);
  91                         err++;
  92                 }
  93         }
  94         if (err)
  95                 return -EINVAL; /* full string handled, report error */
  96
  97         return len;
  98 }
  99
 100 ssize_t nsc_gpio_read(struct file *file, char __user * buf,
 101                       size_t len, loff_t * ppos)
 102 {
 103         unsigned m = iminor(file->f_dentry->d_inode);
 104         int value;
 105         struct nsc_gpio_ops *amp = file->private_data;
 106
 107         value = amp->gpio_get(m);
 108         if (put_user(value ? '1' : '0', buf))
 109                 return -EFAULT;
 110
 111         return 1;
 112 }
 113
 114 /* common file-ops routines for both scx200_gpio and pc87360_gpio */
 115 EXPORT_SYMBOL(nsc_gpio_write);
 116 EXPORT_SYMBOL(nsc_gpio_read);
 117 EXPORT_SYMBOL(nsc_gpio_dump);
 118
 119 static int __init nsc_gpio_init(void)
 120 {
 121         printk(KERN_DEBUG NAME " initializing\n");
 122         return 0;
 123 }
 124
 125 static void __exit nsc_gpio_cleanup(void)
 126 {
 127         printk(KERN_DEBUG NAME " cleanup\n");
 128 }
 129
 130 module_init(nsc_gpio_init);
 131 module_exit(nsc_gpio_cleanup);
 132
 133 MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
 134 MODULE_DESCRIPTION("NatSemi GPIO Common Methods");
 135 MODULE_LICENSE("GPL");