drivers/auxdisplay/ks0108.c

   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