LXR linux/drivers/staging/fbtft/fb

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * FB driver for the PCD8544 LCD Controller
   4 *
   5 * The display is monochrome and the video memory is RGB565.
   6 * Any pixel value except 0 turns the pixel on.
   7 *
   8 * Copyright (C) 2013 Noralf Tronnes
   9 */
  10
  11#include <linux/module.h>
  12#include <linux/kernel.h>
  13#include <linux/init.h>
  14#include <linux/gpio/consumer.h>
  15#include <linux/spi/spi.h>
  16#include <linux/delay.h>
  17
  18#include "fbtft.h"
  19
  20#define DRVNAME        "fb_pcd8544"
  21#define WIDTH          84
  22#define HEIGHT         48
  23#define TXBUFLEN       (84 * 6)
  24#define DEFAULT_GAMMA  "40" /* gamma controls the contrast in this driver */
  25
  26static unsigned int tc;
  27module_param(tc, uint, 0000);
  28MODULE_PARM_DESC(tc, "TC[1:0] Temperature coefficient: 0-3 (default: 0)");
  29
  30static unsigned int bs = 4;
  31module_param(bs, uint, 0000);
  32MODULE_PARM_DESC(bs, "BS[2:0] Bias voltage level: 0-7 (default: 4)");
  33
  34static int init_display(struct fbtft_par *par)
  35{
  36        par->fbtftops.reset(par);
  37
  38        /* Function set
  39         *
  40         * 5:1  1
  41         * 2:0  PD - Powerdown control: chip is active
  42         * 1:0  V  - Entry mode: horizontal addressing
  43         * 0:1  H  - Extended instruction set control: extended
  44         */
  45        write_reg(par, 0x21);
  46
  47        /* H=1 Temperature control
  48         *
  49         * 2:1  1
  50         * 1:x  TC1 - Temperature Coefficient: 0x10
  51         * 0:x  TC0
  52         */
  53        write_reg(par, 0x04 | (tc & 0x3));
  54
  55        /* H=1 Bias system
  56         *
  57         * 4:1  1
  58         * 3:0  0
  59         * 2:x  BS2 - Bias System
  60         * 1:x  BS1
  61         * 0:x  BS0
  62         */
  63        write_reg(par, 0x10 | (bs & 0x7));
  64
  65        /* Function set
  66         *
  67         * 5:1  1
  68         * 2:0  PD - Powerdown control: chip is active
  69         * 1:1  V  - Entry mode: vertical addressing
  70         * 0:0  H  - Extended instruction set control: basic
  71         */
  72        write_reg(par, 0x22);
  73
  74        /* H=0 Display control
  75         *
  76         * 3:1  1
  77         * 2:1  D  - DE: 10=normal mode
  78         * 1:0  0
  79         * 0:0  E
  80         */
  81        write_reg(par, 0x08 | 4);
  82
  83        return 0;
  84}
  85
  86static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
  87{
  88        /* H=0 Set X address of RAM
  89         *
  90         * 7:1  1
  91         * 6-0: X[6:0] - 0x00
  92         */
  93        write_reg(par, 0x80);
  94
  95        /* H=0 Set Y address of RAM
  96         *
  97         * 7:0  0
  98         * 6:1  1
  99         * 2-0: Y[2:0] - 0x0
 100         */
 101        write_reg(par, 0x40);
 102}
 103
 104static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
 105{
 106        u16 *vmem16 = (u16 *)par->info->screen_buffer;
 107        u8 *buf = par->txbuf.buf;
 108        int x, y, i;
 109        int ret = 0;
 110
 111        for (x = 0; x < 84; x++) {
 112                for (y = 0; y < 6; y++) {
 113                        *buf = 0x00;
 114                        for (i = 0; i < 8; i++)
 115                                *buf |= (vmem16[(y * 8 + i) * 84 + x] ?
 116                                         1 : 0) << i;
 117                        buf++;
 118                }
 119        }
 120
 121        /* Write data */
 122        gpiod_set_value(par->gpio.dc, 1);
 123        ret = par->fbtftops.write(par, par->txbuf.buf, 6 * 84);
 124        if (ret < 0)
 125                dev_err(par->info->device, "write failed and returned: %d\n",
 126                        ret);
 127
 128        return ret;
 129}
 130
 131static int set_gamma(struct fbtft_par *par, u32 *curves)
 132{
 133        /* apply mask */
 134        curves[0] &= 0x7F;
 135
 136        write_reg(par, 0x23); /* turn on extended instruction set */
 137        write_reg(par, 0x80 | curves[0]);
 138        write_reg(par, 0x22); /* turn off extended instruction set */
 139
 140        return 0;
 141}
 142
 143static struct fbtft_display display = {
 144        .regwidth = 8,
 145        .width = WIDTH,
 146        .height = HEIGHT,
 147        .txbuflen = TXBUFLEN,
 148        .gamma_num = 1,
 149        .gamma_len = 1,
 150        .gamma = DEFAULT_GAMMA,
 151        .fbtftops = {
 152                .init_display = init_display,
 153                .set_addr_win = set_addr_win,
 154                .write_vmem = write_vmem,
 155                .set_gamma = set_gamma,
 156        },
 157        .backlight = 1,
 158};
 159
 160FBTFT_REGISTER_DRIVER(DRVNAME, "philips,pcd8544", &display);
 161
 162MODULE_ALIAS("spi:" DRVNAME);
 163MODULE_ALIAS("spi:pcd8544");
 164
 165MODULE_DESCRIPTION("FB driver for the PCD8544 LCD Controller");
 166MODULE_AUTHOR("Noralf Tronnes");
 167MODULE_LICENSE("GPL");
 168