drivers/staging/fbtft/fb_tls8204.c

   1 /*
   2  * FB driver for the TLS8204 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  * Copyright (C) 2014 Michael Hope (adapted for the TLS8204)
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/kernel.h>
  23 #include <linux/init.h>
  24 #include <linux/gpio.h>
  25 #include <linux/spi/spi.h>
  26 #include <linux/delay.h>
  27
  28 #include "fbtft.h"
  29
  30 #define DRVNAME         "fb_tls8204"
  31 #define WIDTH           84
  32 #define HEIGHT          48
  33 #define TXBUFLEN        WIDTH
  34
  35 /* gamma is used to control contrast in this driver */
  36 #define DEFAULT_GAMMA   "40"
  37
  38 static unsigned bs = 4;
  39 module_param(bs, uint, 0);
  40 MODULE_PARM_DESC(bs, "BS[2:0] Bias voltage level: 0-7 (default: 4)");
  41
  42 static int init_display(struct fbtft_par *par)
  43 {
  44         par->fbtftops.reset(par);
  45
  46         /* Enter extended command mode */
  47         write_reg(par, 0x21); /* 5:1  1
  48                                  2:0  PD - Powerdown control: chip is active
  49                                  1:0  V  - Entry mode: horizontal addressing
  50                                  0:1  H  - Extended instruction set control:
  51                                                 extended
  52                               */
  53
  54         /* H=1 Bias system */
  55         write_reg(par, 0x10 | (bs & 0x7)); /*
  56                                  4:1  1
  57                                  3:0  0
  58                                  2:x  BS2 - Bias System
  59                                  1:x  BS1
  60                                  0:x  BS0
  61                               */
  62
  63         /* Set the address of the first display line. */
  64         write_reg(par, 0x04 | (64 >> 6));
  65         write_reg(par, 0x40 | (64 & 0x3F));
  66
  67         /* Enter H=0 standard command mode */
  68         write_reg(par, 0x20);
  69
  70         /* H=0 Display control */
  71         write_reg(par, 0x08 | 4); /*
  72                                  3:1  1
  73                                  2:1  D  - DE: 10=normal mode
  74                                  1:0  0
  75                                  0:0  E
  76                               */
  77
  78         return 0;
  79 }
  80
  81 static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
  82 {
  83         /* H=0 Set X address of RAM */
  84         write_reg(par, 0x80); /* 7:1  1
  85                                  6-0: X[6:0] - 0x00
  86                               */
  87
  88         /* H=0 Set Y address of RAM */
  89         write_reg(par, 0x40); /* 7:0  0
  90                                  6:1  1
  91                                  2-0: Y[2:0] - 0x0
  92                               */
  93 }
  94
  95 static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
  96 {
  97         u16 *vmem16 = (u16 *)par->info->screen_buffer;
  98         int x, y, i;
  99         int ret = 0;
 100
 101         for (y = 0; y < HEIGHT / 8; y++) {
 102                 u8 *buf = par->txbuf.buf;
 103                 /* The display is 102x68 but the LCD is 84x48.  Set
 104                    the write pointer at the start of each row. */
 105                 gpio_set_value(par->gpio.dc, 0);
 106                 write_reg(par, 0x80 | 0);
 107                 write_reg(par, 0x40 | y);
 108
 109                 for (x = 0; x < WIDTH; x++) {
 110                         u8 ch = 0;
 111
 112                         for (i = 0; i < 8 * WIDTH; i += WIDTH) {
 113                                 ch >>= 1;
 114                                 if (vmem16[(y * 8 * WIDTH) + i + x])
 115                                         ch |= 0x80;
 116                         }
 117                         *buf++ = ch;
 118                 }
 119                 /* Write the row */
 120                 gpio_set_value(par->gpio.dc, 1);
 121                 ret = par->fbtftops.write(par, par->txbuf.buf, WIDTH);
 122                 if (ret < 0) {
 123                         dev_err(par->info->device,
 124                                 "write failed and returned: %d\n", ret);
 125                         break;
 126                 }
 127         }
 128
 129         return ret;
 130 }
 131
 132 static int set_gamma(struct fbtft_par *par, unsigned long *curves)
 133 {
 134         /* apply mask */
 135         curves[0] &= 0x7F;
 136
 137         write_reg(par, 0x21); /* turn on extended instruction set */
 138         write_reg(par, 0x80 | curves[0]);
 139         write_reg(par, 0x20); /* turn off extended instruction set */
 140
 141         return 0;
 142 }
 143
 144 static struct fbtft_display display = {
 145         .regwidth = 8,
 146         .width = WIDTH,
 147         .height = HEIGHT,
 148         .txbuflen = TXBUFLEN,
 149         .gamma_num = 1,
 150         .gamma_len = 1,
 151         .gamma = DEFAULT_GAMMA,
 152         .fbtftops = {
 153                 .init_display = init_display,
 154                 .set_addr_win = set_addr_win,
 155                 .write_vmem = write_vmem,
 156                 .set_gamma = set_gamma,
 157         },
 158         .backlight = 1,
 159 };
 160
 161 FBTFT_REGISTER_DRIVER(DRVNAME, "teralane,tls8204", &display);
 162
 163 MODULE_ALIAS("spi:" DRVNAME);
 164 MODULE_ALIAS("spi:tls8204");
 165
 166 MODULE_DESCRIPTION("FB driver for the TLS8204 LCD Controller");
 167 MODULE_AUTHOR("Michael Hope");
 168 MODULE_LICENSE("GPL");