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