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/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 <linux/uaccess.h>
  18 #include <asm/io.h>
  19
  20 #define NAME "nsc_gpio"
  21
  22 void 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
  41 ssize_t nsc_gpio_write(struct file *file, const char __user *data,
  42                        size_t len, loff_t *ppos)
  43 {
  44         unsigned m = iminor(file_inode(file));
  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
 104 ssize_t nsc_gpio_read(struct file *file, char __user * buf,
 105                       size_t len, loff_t * ppos)
 106 {
 107         unsigned m = iminor(file_inode(file));
 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 */
 119 EXPORT_SYMBOL(nsc_gpio_write);
 120 EXPORT_SYMBOL(nsc_gpio_read);
 121 EXPORT_SYMBOL(nsc_gpio_dump);
 122
 123 static int __init nsc_gpio_init(void)
 124 {
 125         printk(KERN_DEBUG NAME " initializing\n");
 126         return 0;
 127 }
 128
 129 static void __exit nsc_gpio_cleanup(void)
 130 {
 131         printk(KERN_DEBUG NAME " cleanup\n");
 132 }
 133
 134 module_init(nsc_gpio_init);
 135 module_exit(nsc_gpio_cleanup);
 136
 137 MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
 138 MODULE_DESCRIPTION("NatSemi GPIO Common Methods");
 139 MODULE_LICENSE("GPL");