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/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 };
 166 module_parport_driver(ks0108_parport_driver);
 167
 168 MODULE_LICENSE("GPL v2");
 169 MODULE_AUTHOR("Miguel Ojeda <ojeda@kernel.org>");
 170 MODULE_DESCRIPTION("ks0108 LCD Controller driver");
 171