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 par->fbtftops.reset(par); 45 46 /* Enter extended command mode */ 47 write_reg(par, 0x21); /* 5:1 1 48 2:0 PD - Powerdown control: chip is active 49 1:0 V - Entry mode: horizontal addressing 50 0:1 H - Extended instruction set control: 51 extended 52 */ 53 54 /* H=1 Bias system */ 55 write_reg(par, 0x10 | (bs & 0x7)); /* 56 4:1 1 57 3:0 0 58 2:x BS2 - Bias System 59 1:x BS1 60 0:x BS0 61 */ 62 63 /* Set the address of the first display line. */ 64 write_reg(par, 0x04 | (64 >> 6)); 65 write_reg(par, 0x40 | (64 & 0x3F)); 66 67 /* Enter H=0 standard command mode */ 68 write_reg(par, 0x20); 69 70 /* H=0 Display control */ 71 write_reg(par, 0x08 | 4); /* 72 3:1 1 73 2:1 D - DE: 10=normal mode 74 1:0 0 75 0:0 E 76 */ 77 78 return 0; 79 } 80 81 static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye) 82 { 83 /* H=0 Set X address of RAM */ 84 write_reg(par, 0x80); /* 7:1 1 85 6-0: X[6:0] - 0x00 86 */ 87 88 /* H=0 Set Y address of RAM */ 89 write_reg(par, 0x40); /* 7:0 0 90 6:1 1 91 2-0: Y[2:0] - 0x0 92 */ 93 } 94 95 static int write_vmem(struct fbtft_par *par, size_t offset, size_t len) 96 { 97 u16 *vmem16 = (u16 *)par->info->screen_buffer; 98 int x, y, i; 99 int ret = 0; 100 101 for (y = 0; y < HEIGHT / 8; y++) { 102 u8 *buf = par->txbuf.buf; 103 /* The display is 102x68 but the LCD is 84x48. Set 104 the write pointer at the start of each row. */ 105 gpio_set_value(par->gpio.dc, 0); 106 write_reg(par, 0x80 | 0); 107 write_reg(par, 0x40 | y); 108 109 for (x = 0; x < WIDTH; x++) { 110 u8 ch = 0; 111 112 for (i = 0; i < 8 * WIDTH; i += WIDTH) { 113 ch >>= 1; 114 if (vmem16[(y * 8 * WIDTH) + i + x]) 115 ch |= 0x80; 116 } 117 *buf++ = ch; 118 } 119 /* Write the row */ 120 gpio_set_value(par->gpio.dc, 1); 121 ret = par->fbtftops.write(par, par->txbuf.buf, WIDTH); 122 if (ret < 0) { 123 dev_err(par->info->device, 124 "write failed and returned: %d\n", ret); 125 break; 126 } 127 } 128 129 return ret; 130 } 131 132 static int set_gamma(struct fbtft_par *par, unsigned long *curves) 133 { 134 /* apply mask */ 135 curves[0] &= 0x7F; 136 137 write_reg(par, 0x21); /* turn on extended instruction set */ 138 write_reg(par, 0x80 | curves[0]); 139 write_reg(par, 0x20); /* turn off extended instruction set */ 140 141 return 0; 142 } 143 144 static struct fbtft_display display = { 145 .regwidth = 8, 146 .width = WIDTH, 147 .height = HEIGHT, 148 .txbuflen = TXBUFLEN, 149 .gamma_num = 1, 150 .gamma_len = 1, 151 .gamma = DEFAULT_GAMMA, 152 .fbtftops = { 153 .init_display = init_display, 154 .set_addr_win = set_addr_win, 155 .write_vmem = write_vmem, 156 .set_gamma = set_gamma, 157 }, 158 .backlight = 1, 159 }; 160 161 FBTFT_REGISTER_DRIVER(DRVNAME, "teralane,tls8204", &display); 162 163 MODULE_ALIAS("spi:" DRVNAME); 164 MODULE_ALIAS("spi:tls8204"); 165 166 MODULE_DESCRIPTION("FB driver for the TLS8204 LCD Controller"); 167 MODULE_AUTHOR("Michael Hope"); 168 MODULE_LICENSE("GPL"); 169