drivers/staging/fbtft/fb_pcd8544.c

   1 /*
   2  * FB driver for the PCD8544 LCD Controller
   3  *
   4  * The display is monochrome and the video memory is RGB565.
   5  * Any pixel value except 0 turns the pixel on.
   6  *
   7  * Copyright (C) 2013 Noralf Tronnes
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  */
  19
  20 #include <linux/module.h>
  21 #include <linux/kernel.h>
  22 #include <linux/init.h>
  23 #include <linux/gpio.h>
  24 #include <linux/spi/spi.h>
  25 #include <linux/delay.h>
  26
  27 #include "fbtft.h"
  28
  29 #define DRVNAME        "fb_pcd8544"
  30 #define WIDTH          84
  31 #define HEIGHT         48
  32 #define TXBUFLEN       (84 * 6)
  33 #define DEFAULT_GAMMA  "40" /* gamma controls the contrast in this driver */
  34
  35 static unsigned tc;
  36 module_param(tc, uint, 0);
  37 MODULE_PARM_DESC(tc, "TC[1:0] Temperature coefficient: 0-3 (default: 0)");
  38
  39 static unsigned bs = 4;
  40 module_param(bs, uint, 0);
  41 MODULE_PARM_DESC(bs, "BS[2:0] Bias voltage level: 0-7 (default: 4)");
  42
  43 static int init_display(struct fbtft_par *par)
  44 {
  45         par->fbtftops.reset(par);
  46
  47         /* Function set
  48          *
  49          * 5:1  1
  50          * 2:0  PD - Powerdown control: chip is active
  51          * 1:0  V  - Entry mode: horizontal addressing
  52          * 0:1  H  - Extended instruction set control: extended
  53          */
  54         write_reg(par, 0x21);
  55
  56         /* H=1 Temperature control
  57          *
  58          * 2:1  1
  59          * 1:x  TC1 - Temperature Coefficient: 0x10
  60          * 0:x  TC0
  61          */
  62         write_reg(par, 0x04 | (tc & 0x3));
  63
  64         /* H=1 Bias system
  65          *
  66          * 4:1  1
  67          * 3:0  0
  68          * 2:x  BS2 - Bias System
  69          * 1:x  BS1
  70          * 0:x  BS0
  71          */
  72         write_reg(par, 0x10 | (bs & 0x7));
  73
  74         /* Function set
  75          *
  76          * 5:1  1
  77          * 2:0  PD - Powerdown control: chip is active
  78          * 1:1  V  - Entry mode: vertical addressing
  79          * 0:0  H  - Extended instruction set control: basic
  80          */
  81         write_reg(par, 0x22);
  82
  83         /* H=0 Display control
  84          *
  85          * 3:1  1
  86          * 2:1  D  - DE: 10=normal mode
  87          * 1:0  0
  88          * 0:0  E
  89          */
  90         write_reg(par, 0x08 | 4);
  91
  92         return 0;
  93 }
  94
  95 static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
  96 {
  97         /* H=0 Set X address of RAM
  98          *
  99          * 7:1  1
 100          * 6-0: X[6:0] - 0x00
 101          */
 102         write_reg(par, 0x80);
 103
 104         /* H=0 Set Y address of RAM
 105          *
 106          * 7:0  0
 107          * 6:1  1
 108          * 2-0: Y[2:0] - 0x0
 109          */
 110         write_reg(par, 0x40);
 111 }
 112
 113 static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
 114 {
 115         u16 *vmem16 = (u16 *)par->info->screen_buffer;
 116         u8 *buf = par->txbuf.buf;
 117         int x, y, i;
 118         int ret = 0;
 119
 120         for (x = 0; x < 84; x++) {
 121                 for (y = 0; y < 6; y++) {
 122                         *buf = 0x00;
 123                         for (i = 0; i < 8; i++)
 124                                 *buf |= (vmem16[(y * 8 + i) * 84 + x] ?
 125                                          1 : 0) << i;
 126                         buf++;
 127                 }
 128         }
 129
 130         /* Write data */
 131         gpio_set_value(par->gpio.dc, 1);
 132         ret = par->fbtftops.write(par, par->txbuf.buf, 6 * 84);
 133         if (ret < 0)
 134                 dev_err(par->info->device, "write failed and returned: %d\n",
 135                         ret);
 136
 137         return ret;
 138 }
 139
 140 static int set_gamma(struct fbtft_par *par, unsigned long *curves)
 141 {
 142         /* apply mask */
 143         curves[0] &= 0x7F;
 144
 145         write_reg(par, 0x23); /* turn on extended instruction set */
 146         write_reg(par, 0x80 | curves[0]);
 147         write_reg(par, 0x22); /* turn off extended instruction set */
 148
 149         return 0;
 150 }
 151
 152 static struct fbtft_display display = {
 153         .regwidth = 8,
 154         .width = WIDTH,
 155         .height = HEIGHT,
 156         .txbuflen = TXBUFLEN,
 157         .gamma_num = 1,
 158         .gamma_len = 1,
 159         .gamma = DEFAULT_GAMMA,
 160         .fbtftops = {
 161                 .init_display = init_display,
 162                 .set_addr_win = set_addr_win,
 163                 .write_vmem = write_vmem,
 164                 .set_gamma = set_gamma,
 165         },
 166         .backlight = 1,
 167 };
 168
 169 FBTFT_REGISTER_DRIVER(DRVNAME, "philips,pdc8544", &display);
 170
 171 MODULE_ALIAS("spi:" DRVNAME);
 172 MODULE_ALIAS("spi:pdc8544");
 173
 174 MODULE_DESCRIPTION("FB driver for the PCD8544 LCD Controller");
 175 MODULE_AUTHOR("Noralf Tronnes");
 176 MODULE_LICENSE("GPL");