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         fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
  45
  46         par->fbtftops.reset(par);
  47
  48         /* Enter extended command mode */
  49         write_reg(par, 0x21); /* 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:
  53                                                 extended
  54                               */
  55
  56         /* H=1 Bias system */
  57         write_reg(par, 0x10 | (bs & 0x7)); /*
  58                                  4:1  1
  59                                  3:0  0
  60                                  2:x  BS2 - Bias System
  61                                  1:x  BS1
  62                                  0:x  BS0
  63                               */
  64
  65         /* Set the address of the first display line. */
  66         write_reg(par, 0x04 | (64 >> 6));
  67         write_reg(par, 0x40 | (64 & 0x3F));
  68
  69         /* Enter H=0 standard command mode */
  70         write_reg(par, 0x20);
  71
  72         /* H=0 Display control */
  73         write_reg(par, 0x08 | 4); /*
  74                                  3:1  1
  75                                  2:1  D  - DE: 10=normal mode
  76                                  1:0  0
  77                                  0:0  E
  78                               */
  79
  80         return 0;
  81 }
  82
  83 static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
  84 {
  85         /* H=0 Set X address of RAM */
  86         write_reg(par, 0x80); /* 7:1  1
  87                                  6-0: X[6:0] - 0x00
  88                               */
  89
  90         /* H=0 Set Y address of RAM */
  91         write_reg(par, 0x40); /* 7:0  0
  92                                  6:1  1
  93                                  2-0: Y[2:0] - 0x0
  94                               */
  95 }
  96
  97 static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
  98 {
  99         u16 *vmem16 = (u16 *)par->info->screen_base;
 100         int x, y, i;
 101         int ret = 0;
 102
 103         fbtft_par_dbg(DEBUG_WRITE_VMEM, par, "%s()\n", __func__);
 104
 105         for (y = 0; y < HEIGHT / 8; y++) {
 106                 u8 *buf = par->txbuf.buf;
 107                 /* The display is 102x68 but the LCD is 84x48.  Set
 108                    the write pointer at the start of each row. */
 109                 gpio_set_value(par->gpio.dc, 0);
 110                 write_reg(par, 0x80 | 0);
 111                 write_reg(par, 0x40 | y);
 112
 113                 for (x = 0; x < WIDTH; x++) {
 114                         u8 ch = 0;
 115
 116                         for (i = 0; i < 8 * WIDTH; i += WIDTH) {
 117                                 ch >>= 1;
 118                                 if (vmem16[(y * 8 * WIDTH) + i + x])
 119                                         ch |= 0x80;
 120                         }
 121                         *buf++ = ch;
 122                 }
 123                 /* Write the row */
 124                 gpio_set_value(par->gpio.dc, 1);
 125                 ret = par->fbtftops.write(par, par->txbuf.buf, WIDTH);
 126                 if (ret < 0) {
 127                         dev_err(par->info->device,
 128                                 "write failed and returned: %d\n", ret);
 129                         break;
 130                 }
 131         }
 132
 133         return ret;
 134 }
 135
 136 static int set_gamma(struct fbtft_par *par, unsigned long *curves)
 137 {
 138         fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
 139
 140         /* apply mask */
 141         curves[0] &= 0x7F;
 142
 143         write_reg(par, 0x21); /* turn on extended instruction set */
 144         write_reg(par, 0x80 | curves[0]);
 145         write_reg(par, 0x20); /* turn off extended instruction set */
 146
 147         return 0;
 148 }
 149
 150 static struct fbtft_display display = {
 151         .regwidth = 8,
 152         .width = WIDTH,
 153         .height = HEIGHT,
 154         .txbuflen = TXBUFLEN,
 155         .gamma_num = 1,
 156         .gamma_len = 1,
 157         .gamma = DEFAULT_GAMMA,
 158         .fbtftops = {
 159                 .init_display = init_display,
 160                 .set_addr_win = set_addr_win,
 161                 .write_vmem = write_vmem,
 162                 .set_gamma = set_gamma,
 163         },
 164         .backlight = 1,
 165 };
 166
 167 FBTFT_REGISTER_DRIVER(DRVNAME, "teralane,tls8204", &display);
 168
 169 MODULE_ALIAS("spi:" DRVNAME);
 170 MODULE_ALIAS("spi:tls8204");
 171
 172 MODULE_DESCRIPTION("FB driver for the TLS8204 LCD Controller");
 173 MODULE_AUTHOR("Michael Hope");
 174 MODULE_LICENSE("GPL");