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,pdc8544", &display); 161 162 MODULE_ALIAS("spi:" DRVNAME); 163 MODULE_ALIAS("spi:pdc8544"); 164 165 MODULE_DESCRIPTION("FB driver for the PCD8544 LCD Controller"); 166 MODULE_AUTHOR("Noralf Tronnes"); 167 MODULE_LICENSE("GPL"); 168