root/drivers/staging/fbtft/fb_pcd8544.c

DEFINITIONS

1. init_display
2. set_addr_win
3. write_vmem
4. set_gamma

   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 
  26 static unsigned int tc;
  27 module_param(tc, uint, 0000);
  28 MODULE_PARM_DESC(tc, "TC[1:0] Temperature coefficient: 0-3 (default: 0)");
  29 
  30 static unsigned int bs = 4;
  31 module_param(bs, uint, 0000);
  32 MODULE_PARM_DESC(bs, "BS[2:0] Bias voltage level: 0-7 (default: 4)");
  33 
  34 static 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 
  86 static 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 
 104 static 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 
 131 static 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 
 143 static 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 
 160 FBTFT_REGISTER_DRIVER(DRVNAME, "philips,pcd8544", &display);
 161 
 162 MODULE_ALIAS("spi:" DRVNAME);
 163 MODULE_ALIAS("spi:pcd8544");
 164 
 165 MODULE_DESCRIPTION("FB driver for the PCD8544 LCD Controller");
 166 MODULE_AUTHOR("Noralf Tronnes");
 167 MODULE_LICENSE("GPL");