141 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/* linux/drivers/char/nsc_gpio.c3 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