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 20 #include <linux/module.h> 21 #include <linux/kernel.h> 22 #include <linux/init.h> 23 #include <linux/gpio.h> 24 #include <linux/spi/spi.h> 25 #include <linux/delay.h> 26 27 #include "fbtft.h" 28 29 #define DRVNAME "fb_pcd8544" 30 #define WIDTH 84 31 #define HEIGHT 48 32 #define TXBUFLEN (84 * 6) 33 #define DEFAULT_GAMMA "40" /* gamma controls the contrast in this driver */ 34 35 static unsigned tc; 36 module_param(tc, uint, 0); 37 MODULE_PARM_DESC(tc, "TC[1:0] Temperature coefficient: 0-3 (default: 0)"); 38 39 static unsigned bs = 4; 40 module_param(bs, uint, 0); 41 MODULE_PARM_DESC(bs, "BS[2:0] Bias voltage level: 0-7 (default: 4)"); 42 43 static int init_display(struct fbtft_par *par) 44 { 45 par->fbtftops.reset(par); 46 47 /* Function set 48 * 49 * 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: extended 53 */ 54 write_reg(par, 0x21); 55 56 /* H=1 Temperature control 57 * 58 * 2:1 1 59 * 1:x TC1 - Temperature Coefficient: 0x10 60 * 0:x TC0 61 */ 62 write_reg(par, 0x04 | (tc & 0x3)); 63 64 /* H=1 Bias system 65 * 66 * 4:1 1 67 * 3:0 0 68 * 2:x BS2 - Bias System 69 * 1:x BS1 70 * 0:x BS0 71 */ 72 write_reg(par, 0x10 | (bs & 0x7)); 73 74 /* Function set 75 * 76 * 5:1 1 77 * 2:0 PD - Powerdown control: chip is active 78 * 1:1 V - Entry mode: vertical addressing 79 * 0:0 H - Extended instruction set control: basic 80 */ 81 write_reg(par, 0x22); 82 83 /* H=0 Display control 84 * 85 * 3:1 1 86 * 2:1 D - DE: 10=normal mode 87 * 1:0 0 88 * 0:0 E 89 */ 90 write_reg(par, 0x08 | 4); 91 92 return 0; 93 } 94 95 static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye) 96 { 97 /* H=0 Set X address of RAM 98 * 99 * 7:1 1 100 * 6-0: X[6:0] - 0x00 101 */ 102 write_reg(par, 0x80); 103 104 /* H=0 Set Y address of RAM 105 * 106 * 7:0 0 107 * 6:1 1 108 * 2-0: Y[2:0] - 0x0 109 */ 110 write_reg(par, 0x40); 111 } 112 113 static int write_vmem(struct fbtft_par *par, size_t offset, size_t len) 114 { 115 u16 *vmem16 = (u16 *)par->info->screen_buffer; 116 u8 *buf = par->txbuf.buf; 117 int x, y, i; 118 int ret = 0; 119 120 for (x = 0; x < 84; x++) { 121 for (y = 0; y < 6; y++) { 122 *buf = 0x00; 123 for (i = 0; i < 8; i++) 124 *buf |= (vmem16[(y * 8 + i) * 84 + x] ? 125 1 : 0) << i; 126 buf++; 127 } 128 } 129 130 /* Write data */ 131 gpio_set_value(par->gpio.dc, 1); 132 ret = par->fbtftops.write(par, par->txbuf.buf, 6 * 84); 133 if (ret < 0) 134 dev_err(par->info->device, "write failed and returned: %d\n", 135 ret); 136 137 return ret; 138 } 139 140 static int set_gamma(struct fbtft_par *par, unsigned long *curves) 141 { 142 /* apply mask */ 143 curves[0] &= 0x7F; 144 145 write_reg(par, 0x23); /* turn on extended instruction set */ 146 write_reg(par, 0x80 | curves[0]); 147 write_reg(par, 0x22); /* turn off extended instruction set */ 148 149 return 0; 150 } 151 152 static struct fbtft_display display = { 153 .regwidth = 8, 154 .width = WIDTH, 155 .height = HEIGHT, 156 .txbuflen = TXBUFLEN, 157 .gamma_num = 1, 158 .gamma_len = 1, 159 .gamma = DEFAULT_GAMMA, 160 .fbtftops = { 161 .init_display = init_display, 162 .set_addr_win = set_addr_win, 163 .write_vmem = write_vmem, 164 .set_gamma = set_gamma, 165 }, 166 .backlight = 1, 167 }; 168 169 FBTFT_REGISTER_DRIVER(DRVNAME, "philips,pdc8544", &display); 170 171 MODULE_ALIAS("spi:" DRVNAME); 172 MODULE_ALIAS("spi:pdc8544"); 173 174 MODULE_DESCRIPTION("FB driver for the PCD8544 LCD Controller"); 175 MODULE_AUTHOR("Noralf Tronnes"); 176 MODULE_LICENSE("GPL"); 177