1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Filename: ks0108.c 4 * Version: 0.1.0 5 * Description: ks0108 LCD Controller driver 6 * Depends: parport 7 * 8 * Author: Copyright (C) Miguel Ojeda <ojeda@kernel.org> 9 * Date: 2006-10-31 10 */ 11 12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 13 14 #include <linux/init.h> 15 #include <linux/module.h> 16 #include <linux/kernel.h> 17 #include <linux/delay.h> 18 #include <linux/fs.h> 19 #include <linux/io.h> 20 #include <linux/parport.h> 21 #include <linux/uaccess.h> 22 #include <linux/ks0108.h> 23 24 #define KS0108_NAME "ks0108" 25 26 /* 27 * Module Parameters 28 */ 29 30 static unsigned int ks0108_port = CONFIG_KS0108_PORT; 31 module_param(ks0108_port, uint, 0444); 32 MODULE_PARM_DESC(ks0108_port, "Parallel port where the LCD is connected"); 33 34 static unsigned int ks0108_delay = CONFIG_KS0108_DELAY; 35 module_param(ks0108_delay, uint, 0444); 36 MODULE_PARM_DESC(ks0108_delay, "Delay between each control writing (microseconds)"); 37 38 /* 39 * Device 40 */ 41 42 static struct parport *ks0108_parport; 43 static struct pardevice *ks0108_pardevice; 44 45 /* 46 * ks0108 Exported Commands (don't lock) 47 * 48 * You _should_ lock in the top driver: This functions _should not_ 49 * get race conditions in any way. Locking for each byte here would be 50 * so slow and useless. 51 * 52 * There are not bit definitions because they are not flags, 53 * just arbitrary combinations defined by the documentation for each 54 * function in the ks0108 LCD controller. If you want to know what means 55 * a specific combination, look at the function's name. 56 * 57 * The ks0108_writecontrol bits need to be reverted ^(0,1,3) because 58 * the parallel port also revert them using a "not" logic gate. 59 */ 60 61 #define bit(n) (((unsigned char)1)<<(n)) 62 63 void ks0108_writedata(unsigned char byte) 64 { 65 parport_write_data(ks0108_parport, byte); 66 } 67 68 void ks0108_writecontrol(unsigned char byte) 69 { 70 udelay(ks0108_delay); 71 parport_write_control(ks0108_parport, byte ^ (bit(0) | bit(1) | bit(3))); 72 } 73 74 void ks0108_displaystate(unsigned char state) 75 { 76 ks0108_writedata((state ? bit(0) : 0) | bit(1) | bit(2) | bit(3) | bit(4) | bit(5)); 77 } 78 79 void ks0108_startline(unsigned char startline) 80 { 81 ks0108_writedata(min_t(unsigned char, startline, 63) | bit(6) | 82 bit(7)); 83 } 84 85 void ks0108_address(unsigned char address) 86 { 87 ks0108_writedata(min_t(unsigned char, address, 63) | bit(6)); 88 } 89 90 void ks0108_page(unsigned char page) 91 { 92 ks0108_writedata(min_t(unsigned char, page, 7) | bit(3) | bit(4) | 93 bit(5) | bit(7)); 94 } 95 96 EXPORT_SYMBOL_GPL(ks0108_writedata); 97 EXPORT_SYMBOL_GPL(ks0108_writecontrol); 98 EXPORT_SYMBOL_GPL(ks0108_displaystate); 99 EXPORT_SYMBOL_GPL(ks0108_startline); 100 EXPORT_SYMBOL_GPL(ks0108_address); 101 EXPORT_SYMBOL_GPL(ks0108_page); 102 103 /* 104 * Is the module inited? 105 */ 106 107 static unsigned char ks0108_inited; 108 unsigned char ks0108_isinited(void) 109 { 110 return ks0108_inited; 111 } 112 EXPORT_SYMBOL_GPL(ks0108_isinited); 113 114 static void ks0108_parport_attach(struct parport *port) 115 { 116 struct pardev_cb ks0108_cb; 117 118 if (port->base != ks0108_port) 119 return; 120 121 memset(&ks0108_cb, 0, sizeof(ks0108_cb)); 122 ks0108_cb.flags = PARPORT_DEV_EXCL; 123 ks0108_pardevice = parport_register_dev_model(port, KS0108_NAME, 124 &ks0108_cb, 0); 125 if (!ks0108_pardevice) { 126 pr_err("ERROR: parport didn't register new device\n"); 127 return; 128 } 129 if (parport_claim(ks0108_pardevice)) { 130 pr_err("could not claim access to parport %i. Aborting.\n", 131 ks0108_port); 132 goto err_unreg_device; 133 } 134 135 ks0108_parport = port; 136 ks0108_inited = 1; 137 return; 138 139 err_unreg_device: 140 parport_unregister_device(ks0108_pardevice); 141 ks0108_pardevice = NULL; 142 } 143 144 static void ks0108_parport_detach(struct parport *port) 145 { 146 if (port->base != ks0108_port) 147 return; 148 149 if (!ks0108_pardevice) { 150 pr_err("%s: already unregistered.\n", KS0108_NAME); 151 return; 152 } 153 154 parport_release(ks0108_pardevice); 155 parport_unregister_device(ks0108_pardevice); 156 ks0108_pardevice = NULL; 157 ks0108_parport = NULL; 158 } 159 160 /* 161 * Module Init & Exit 162 */ 163 164 static struct parport_driver ks0108_parport_driver = { 165 .name = "ks0108", 166 .match_port = ks0108_parport_attach, 167 .detach = ks0108_parport_detach, 168 .devmodel = true, 169 }; 170 module_parport_driver(ks0108_parport_driver); 171 172 MODULE_LICENSE("GPL v2"); 173 MODULE_AUTHOR("Miguel Ojeda <ojeda@kernel.org>"); 174 MODULE_DESCRIPTION("ks0108 LCD Controller driver"); 175 176