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