drivers/char/nsc_gpio.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* linux/drivers/char/nsc_gpio.c
   3
   4    National Semiconductor common GPIO device-file/VFS methods.
   5    Allows a user space process to control the GPIO pins.
   6
   7    Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
   8    Copyright (c) 2005      Jim Cromie <jim.cromie@gmail.com>
   9 */
  10
  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 <linux/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_inode(file));
  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", m);
  72                         amp->gpio_config(m, ~2, 2);
  73                         break;
  74                 case 't':
  75                         dev_dbg(dev, "GPIO%d output is open drain\n", m);
  76                         amp->gpio_config(m, ~2, 0);
  77                         break;
  78                 case 'P':
  79                         dev_dbg(dev, "GPIO%d pull up enabled\n", m);
  80                         amp->gpio_config(m, ~4, 4);
  81                         break;
  82                 case 'p':
  83                         dev_dbg(dev, "GPIO%d pull up disabled\n", m);
  84                         amp->gpio_config(m, ~4, 0);
  85                         break;
  86                 case 'v':
  87                         /* View Current pin settings */
  88                         amp->gpio_dump(amp, m);
  89                         break;
  90                 case '\n':
  91                         /* end of settings string, do nothing */
  92                         break;
  93                 default:
  94                         dev_err(dev, "io%2d bad setting: chr<0x%2x>\n",
  95                                 m, (int)c);
  96                         err++;
  97                 }
  98         }
  99         if (err)
 100                 return -EINVAL; /* full string handled, report error */
 101
 102         return len;
 103 }
 104
 105 ssize_t nsc_gpio_read(struct file *file, char __user * buf,
 106                       size_t len, loff_t * ppos)
 107 {
 108         unsigned m = iminor(file_inode(file));
 109         int value;
 110         struct nsc_gpio_ops *amp = file->private_data;
 111
 112         value = amp->gpio_get(m);
 113         if (put_user(value ? '1' : '0', buf))
 114                 return -EFAULT;
 115
 116         return 1;
 117 }
 118
 119 /* common file-ops routines for both scx200_gpio and pc87360_gpio */
 120 EXPORT_SYMBOL(nsc_gpio_write);
 121 EXPORT_SYMBOL(nsc_gpio_read);
 122 EXPORT_SYMBOL(nsc_gpio_dump);
 123
 124 static int __init nsc_gpio_init(void)
 125 {
 126         printk(KERN_DEBUG NAME " initializing\n");
 127         return 0;
 128 }
 129
 130 static void __exit nsc_gpio_cleanup(void)
 131 {
 132         printk(KERN_DEBUG NAME " cleanup\n");
 133 }
 134
 135 module_init(nsc_gpio_init);
 136 module_exit(nsc_gpio_cleanup);
 137
 138 MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
 139 MODULE_DESCRIPTION("NatSemi GPIO Common Methods");
 140 MODULE_LICENSE("GPL");