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"); 141