LXR linux/drivers/staging/fbtft/fb

   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 controls the contrast in this driver */
  38
  39static unsigned tc;
  40module_param(tc, uint, 0);
  41MODULE_PARM_DESC(tc, "TC[1:0] Temperature coefficient: 0-3 (default: 0)");
  42
  43static unsigned bs = 4;
  44module_param(bs, uint, 0);
  45MODULE_PARM_DESC(bs, "BS[2:0] Bias voltage level: 0-7 (default: 4)");
  46
  47
  48static 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         *
  56         * 5:1  1
  57         * 2:0  PD - Powerdown control: chip is active
  58         * 1:0  V  - Entry mode: horizontal addressing
  59         * 0:1  H  - Extended instruction set control: extended
  60         */
  61        write_reg(par, 0x21);
  62
  63        /* H=1 Temperature control
  64         *
  65         * 2:1  1
  66         * 1:x  TC1 - Temperature Coefficient: 0x10
  67         * 0:x  TC0
  68         */
  69        write_reg(par, 0x04 | (tc & 0x3));
  70
  71        /* H=1 Bias system
  72         *
  73         * 4:1  1
  74         * 3:0  0
  75         * 2:x  BS2 - Bias System
  76         * 1:x  BS1
  77         * 0:x  BS0
  78         */
  79        write_reg(par, 0x10 | (bs & 0x7));
  80
  81        /* Function set
  82         *
  83         * 5:1  1
  84         * 2:0  PD - Powerdown control: chip is active
  85         * 1:1  V  - Entry mode: vertical addressing
  86         * 0:0  H  - Extended instruction set control: basic
  87         */
  88        write_reg(par, 0x22);
  89
  90        /* H=0 Display control
  91         *
  92         * 3:1  1
  93         * 2:1  D  - DE: 10=normal mode
  94         * 1:0  0
  95         * 0:0  E
  96         */
  97        write_reg(par, 0x08 | 4);
  98
  99        return 0;
 100}
 101
 102static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
 103{
 104        fbtft_par_dbg(DEBUG_SET_ADDR_WIN, par, "%s(xs=%d, ys=%d, xe=%d, ye=%d)\n",
 105                      __func__, xs, ys, xe, ye);
 106
 107        /* H=0 Set X address of RAM
 108         *
 109         * 7:1  1
 110         * 6-0: X[6:0] - 0x00
 111         */
 112        write_reg(par, 0x80);
 113
 114        /* H=0 Set Y address of RAM
 115         *
 116         * 7:0  0
 117         * 6:1  1
 118         * 2-0: Y[2:0] - 0x0
 119         */
 120        write_reg(par, 0x40);
 121}
 122
 123static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
 124{
 125        u16 *vmem16 = (u16 *)par->info->screen_base;
 126        u8 *buf = par->txbuf.buf;
 127        int x, y, i;
 128        int ret = 0;
 129
 130        fbtft_par_dbg(DEBUG_WRITE_VMEM, par, "%s()\n", __func__);
 131
 132        for (x = 0; x < 84; x++) {
 133                for (y = 0; y < 6; y++) {
 134                        *buf = 0x00;
 135                        for (i = 0; i < 8; i++)
 136                                *buf |= (vmem16[(y*8+i)*84+x] ? 1 : 0) << i;
 137                        buf++;
 138                }
 139        }
 140
 141        /* Write data */
 142        gpio_set_value(par->gpio.dc, 1);
 143        ret = par->fbtftops.write(par, par->txbuf.buf, 6*84);
 144        if (ret < 0)
 145                dev_err(par->info->device, "write failed and returned: %d\n",
 146                        ret);
 147
 148        return ret;
 149}
 150
 151static int set_gamma(struct fbtft_par *par, unsigned long *curves)
 152{
 153        fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
 154
 155        /* apply mask */
 156        curves[0] &= 0x7F;
 157
 158        write_reg(par, 0x23); /* turn on extended instruction set */
 159        write_reg(par, 0x80 | curves[0]);
 160        write_reg(par, 0x22); /* turn off extended instruction set */
 161
 162        return 0;
 163}
 164
 165
 166static struct fbtft_display display = {
 167        .regwidth = 8,
 168        .width = WIDTH,
 169        .height = HEIGHT,
 170        .txbuflen = TXBUFLEN,
 171        .gamma_num = 1,
 172        .gamma_len = 1,
 173        .gamma = DEFAULT_GAMMA,
 174        .fbtftops = {
 175                .init_display = init_display,
 176                .set_addr_win = set_addr_win,
 177                .write_vmem = write_vmem,
 178                .set_gamma = set_gamma,
 179        },
 180        .backlight = 1,
 181};
 182FBTFT_REGISTER_DRIVER(DRVNAME, "philips,pdc8544", &display);
 183
 184MODULE_ALIAS("spi:" DRVNAME);
 185MODULE_ALIAS("spi:pdc8544");
 186
 187MODULE_DESCRIPTION("FB driver for the PCD8544 LCD Controller");
 188MODULE_AUTHOR("Noralf Tronnes");
 189MODULE_LICENSE("GPL");
 190