1 /* linux/drivers/char/scx200_gpio.c 2 3 National Semiconductor SCx200 GPIO driver. Allows a user space 4 process to play with the GPIO pins. 5 6 Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> */ 7 8 #include <linux/config.h> 9 #include <linux/fs.h> 10 #include <linux/module.h> 11 #include <linux/errno.h> 12 #include <linux/kernel.h> 13 #include <linux/init.h> 14 #include <asm/uaccess.h> 15 #include <asm/io.h> 16 17 #include <linux/scx200_gpio.h> 18 19 #define NAME "scx200_gpio" 20 21 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>"); 22 MODULE_DESCRIPTION("NatSemi SCx200 GPIO Pin Driver"); 23 MODULE_LICENSE("GPL"); 24 25 static int major = 0; /* default to dynamic major */ 26 module_param(major, int, 0); 27 MODULE_PARM_DESC(major, "Major device number"); 28 29 static ssize_t scx200_gpio_write(struct file *file, const char __user *data, 30 size_t len, loff_t *ppos) 31 { 32 unsigned m = iminor(file->f_dentry->d_inode); 33 size_t i; 34 35 for (i = 0; i < len; ++i) { 36 char c; 37 if (get_user(c, data+i)) 38 return -EFAULT; 39 switch (c) 40 { 41 case '0': 42 scx200_gpio_set(m, 0); 43 break; 44 case '1': 45 scx200_gpio_set(m, 1); 46 break; 47 case 'O': 48 printk(KERN_INFO NAME ": GPIO%d output enabled\n", m); 49 scx200_gpio_configure(m, ~1, 1); 50 break; 51 case 'o': 52 printk(KERN_INFO NAME ": GPIO%d output disabled\n", m); 53 scx200_gpio_configure(m, ~1, 0); 54 break; 55 case 'T': 56 printk(KERN_INFO NAME ": GPIO%d output is push pull\n", m); 57 scx200_gpio_configure(m, ~2, 2); 58 break; 59 case 't': 60 printk(KERN_INFO NAME ": GPIO%d output is open drain\n", m); 61 scx200_gpio_configure(m, ~2, 0); 62 break; 63 case 'P': 64 printk(KERN_INFO NAME ": GPIO%d pull up enabled\n", m); 65 scx200_gpio_configure(m, ~4, 4); 66 break; 67 case 'p': 68 printk(KERN_INFO NAME ": GPIO%d pull up disabled\n", m); 69 scx200_gpio_configure(m, ~4, 0); 70 break; 71 } 72 } 73 74 return len; 75 } 76 77 static ssize_t scx200_gpio_read(struct file *file, char __user *buf, 78 size_t len, loff_t *ppos) 79 { 80 unsigned m = iminor(file->f_dentry->d_inode); 81 int value; 82 83 value = scx200_gpio_get(m); 84 if (put_user(value ? '1' : '0', buf)) 85 return -EFAULT; 86 87 return 1; 88 } 89 90 static int scx200_gpio_open(struct inode *inode, struct file *file) 91 { 92 unsigned m = iminor(inode); 93 if (m > 63) 94 return -EINVAL; 95 return nonseekable_open(inode, file); 96 } 97 98 static int scx200_gpio_release(struct inode *inode, struct file *file) 99 { 100 return 0; 101 } 102 103 104 static struct file_operations scx200_gpio_fops = { 105 .owner = THIS_MODULE, 106 .write = scx200_gpio_write, 107 .read = scx200_gpio_read, 108 .open = scx200_gpio_open, 109 .release = scx200_gpio_release, 110 }; 111 112 static int __init scx200_gpio_init(void) 113 { 114 int r; 115 116 printk(KERN_DEBUG NAME ": NatSemi SCx200 GPIO Driver\n"); 117 118 if (!scx200_gpio_present()) { 119 printk(KERN_ERR NAME ": no SCx200 gpio pins available\n"); 120 return -ENODEV; 121 } 122 123 r = register_chrdev(major, NAME, &scx200_gpio_fops); 124 if (r < 0) { 125 printk(KERN_ERR NAME ": unable to register character device\n"); 126 return r; 127 } 128 if (!major) { 129 major = r; 130 printk(KERN_DEBUG NAME ": got dynamic major %d\n", major); 131 } 132 133 return 0; 134 } 135 136 static void __exit scx200_gpio_cleanup(void) 137 { 138 unregister_chrdev(major, NAME); 139 } 140 141 module_init(scx200_gpio_init); 142 module_exit(scx200_gpio_cleanup); 143 144 /* 145 Local variables: 146 compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules" 147 c-basic-offset: 8 148 End: 149 */ 150