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  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22  */
  23
  24 #include <linux/module.h>
  25 #include <linux/kernel.h>
  26 #include <linux/init.h>
  27 #include <linux/gpio.h>
  28 #include <linux/spi/spi.h>
  29 #include <linux/delay.h>
  30
  31 #include "fbtft.h"
  32
  33 #define DRVNAME        "fb_pcd8544"
  34 #define WIDTH          84
  35 #define HEIGHT         48
  36 #define TXBUFLEN       (84*6)
  37 #define DEFAULT_GAMMA  "40" /* gamma is used to control contrast in this driver */
  38
  39 static unsigned tc;
  40 module_param(tc, uint, 0);
  41 MODULE_PARM_DESC(tc, "TC[1:0] Temperature coefficient: 0-3 (default: 0)");
  42
  43 static unsigned bs = 4;
  44 module_param(bs, uint, 0);
  45 MODULE_PARM_DESC(bs, "BS[2:0] Bias voltage level: 0-7 (default: 4)");
  46
  47
  48 static int init_display(struct fbtft_par *par)
  49 {
  50         fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
  51
  52         par->fbtftops.reset(par);
  53
  54         /* Function set */
  55         write_reg(par, 0x21); /* 5:1  1
  56                                  2:0  PD - Powerdown control: chip is active
  57                                                          1:0  V  - Entry mode: horizontal addressing
  58                                                          0:1  H  - Extended instruction set control: extended
  59                                                   */
  60
  61         /* H=1 Temperature control */
  62         write_reg(par, 0x04 | (tc & 0x3)); /*
  63                                  2:1  1
  64                                  1:x  TC1 - Temperature Coefficient: 0x10
  65                                                          0:x  TC0
  66                                                   */
  67
  68         /* H=1 Bias system */
  69         write_reg(par, 0x10 | (bs & 0x7)); /*
  70                                  4:1  1
  71                                  3:0  0
  72                                                          2:x  BS2 - Bias System
  73                                                          1:x  BS1
  74                                                          0:x  BS0
  75                               */
  76
  77         /* Function set */
  78         write_reg(par, 0x22); /* 5:1  1
  79                                  2:0  PD - Powerdown control: chip is active
  80                                                          1:1  V  - Entry mode: vertical addressing
  81                                                          0:0  H  - Extended instruction set control: basic
  82                                                   */
  83
  84         /* H=0 Display control */
  85         write_reg(par, 0x08 | 4); /*
  86                                  3:1  1
  87                                  2:1  D  - DE: 10=normal mode
  88                                                          1:0  0
  89                                                          0:0  E
  90                                                   */
  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         fbtft_par_dbg(DEBUG_SET_ADDR_WIN, par, "%s(xs=%d, ys=%d, xe=%d, ye=%d)\n", __func__, xs, ys, xe, ye);
  98
  99         /* H=0 Set X address of RAM */
 100         write_reg(par, 0x80); /* 7:1  1
 101                                  6-0: X[6:0] - 0x00
 102                               */
 103
 104         /* H=0 Set Y address of RAM */
 105         write_reg(par, 0x40); /* 7:0  0
 106                                  6:1  1
 107                                  2-0: Y[2:0] - 0x0
 108                               */
 109 }
 110
 111 static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
 112 {
 113         u16 *vmem16 = (u16 *)par->info->screen_base;
 114         u8 *buf = par->txbuf.buf;
 115         int x, y, i;
 116         int ret = 0;
 117
 118         fbtft_par_dbg(DEBUG_WRITE_VMEM, par, "%s()\n", __func__);
 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] ? 1 : 0) << i;
 125                         }
 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, "%s: write failed and returned: %d\n", __func__, ret);
 135
 136         return ret;
 137 }
 138
 139 static int set_gamma(struct fbtft_par *par, unsigned long *curves)
 140 {
 141         fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
 142
 143         /* apply mask */
 144         curves[0] &= 0x7F;
 145
 146         write_reg(par, 0x23); /* turn on extended instruction set */
 147         write_reg(par, 0x80 | curves[0]);
 148         write_reg(par, 0x22); /* turn off extended instruction set */
 149
 150         return 0;
 151 }
 152
 153
 154 static struct fbtft_display display = {
 155         .regwidth = 8,
 156         .width = WIDTH,
 157         .height = HEIGHT,
 158         .txbuflen = TXBUFLEN,
 159         .gamma_num = 1,
 160         .gamma_len = 1,
 161         .gamma = DEFAULT_GAMMA,
 162         .fbtftops = {
 163                 .init_display = init_display,
 164                 .set_addr_win = set_addr_win,
 165                 .write_vmem = write_vmem,
 166                 .set_gamma = set_gamma,
 167         },
 168         .backlight = 1,
 169 };
 170 FBTFT_REGISTER_DRIVER(DRVNAME, "philips,pdc8544", &display);
 171
 172 MODULE_ALIAS("spi:" DRVNAME);
 173 MODULE_ALIAS("spi:pdc8544");
 174
 175 MODULE_DESCRIPTION("FB driver for the PCD8544 LCD Controller");
 176 MODULE_AUTHOR("Noralf Tronnes");
 177 MODULE_LICENSE("GPL");