LXR linux/drivers/char/nsc

   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
  23void 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
  42ssize_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
 105ssize_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 */
 120EXPORT_SYMBOL(nsc_gpio_write);
 121EXPORT_SYMBOL(nsc_gpio_read);
 122EXPORT_SYMBOL(nsc_gpio_dump);
 123
 124static int __init nsc_gpio_init(void)
 125{
 126        printk(KERN_DEBUG NAME " initializing\n");
 127        return 0;
 128}
 129
 130static void __exit nsc_gpio_cleanup(void)
 131{
 132        printk(KERN_DEBUG NAME " cleanup\n");
 133}
 134
 135module_init(nsc_gpio_init);
 136module_exit(nsc_gpio_cleanup);
 137
 138MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
 139MODULE_DESCRIPTION("NatSemi GPIO Common Methods");
 140MODULE_LICENSE("GPL");
 141