LXR linux/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
  30static unsigned int ks0108_port = CONFIG_KS0108_PORT;
  31module_param(ks0108_port, uint, 0444);
  32MODULE_PARM_DESC(ks0108_port, "Parallel port where the LCD is connected");
  33
  34static unsigned int ks0108_delay = CONFIG_KS0108_DELAY;
  35module_param(ks0108_delay, uint, 0444);
  36MODULE_PARM_DESC(ks0108_delay, "Delay between each control writing (microseconds)");
  37
  38/*
  39 * Device
  40 */
  41
  42static struct parport *ks0108_parport;
  43static 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
  63void ks0108_writedata(unsigned char byte)
  64{
  65        parport_write_data(ks0108_parport, byte);
  66}
  67
  68void 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
  74void 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
  79void ks0108_startline(unsigned char startline)
  80{
  81        ks0108_writedata(min_t(unsigned char, startline, 63) | bit(6) |
  82                         bit(7));
  83}
  84
  85void ks0108_address(unsigned char address)
  86{
  87        ks0108_writedata(min_t(unsigned char, address, 63) | bit(6));
  88}
  89
  90void 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
  96EXPORT_SYMBOL_GPL(ks0108_writedata);
  97EXPORT_SYMBOL_GPL(ks0108_writecontrol);
  98EXPORT_SYMBOL_GPL(ks0108_displaystate);
  99EXPORT_SYMBOL_GPL(ks0108_startline);
 100EXPORT_SYMBOL_GPL(ks0108_address);
 101EXPORT_SYMBOL_GPL(ks0108_page);
 102
 103/*
 104 * Is the module inited?
 105 */
 106
 107static unsigned char ks0108_inited;
 108unsigned char ks0108_isinited(void)
 109{
 110        return ks0108_inited;
 111}
 112EXPORT_SYMBOL_GPL(ks0108_isinited);
 113
 114static 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
 139err_unreg_device:
 140        parport_unregister_device(ks0108_pardevice);
 141        ks0108_pardevice = NULL;
 142}
 143
 144static 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
 164static struct parport_driver ks0108_parport_driver = {
 165        .name = "ks0108",
 166        .match_port = ks0108_parport_attach,
 167        .detach = ks0108_parport_detach,
 168        .devmodel = true,
 169};
 170module_parport_driver(ks0108_parport_driver);
 171
 172MODULE_LICENSE("GPL v2");
 173MODULE_AUTHOR("Miguel Ojeda <ojeda@kernel.org>");
 174MODULE_DESCRIPTION("ks0108 LCD Controller driver");
 175
 176