fb_ssd1325.c (4344B)
1// SPDX-License-Identifier: GPL-2.0+ 2/* 3 * FB driver for the SSD1325 OLED Controller 4 */ 5 6#include <linux/module.h> 7#include <linux/kernel.h> 8#include <linux/init.h> 9#include <linux/gpio/consumer.h> 10#include <linux/delay.h> 11 12#include "fbtft.h" 13 14#define DRVNAME "fb_ssd1325" 15 16#define WIDTH 128 17#define HEIGHT 64 18#define GAMMA_NUM 1 19#define GAMMA_LEN 15 20#define DEFAULT_GAMMA "7 1 1 1 1 2 2 3 3 4 4 5 5 6 6" 21 22/* 23 * write_reg() caveat: 24 * 25 * This doesn't work because D/C has to be LOW for both values: 26 * write_reg(par, val1, val2); 27 * 28 * Do it like this: 29 * write_reg(par, val1); 30 * write_reg(par, val2); 31 */ 32 33/* Init sequence taken from the Adafruit SSD1306 Arduino library */ 34static int init_display(struct fbtft_par *par) 35{ 36 par->fbtftops.reset(par); 37 38 write_reg(par, 0xb3); 39 write_reg(par, 0xf0); 40 write_reg(par, 0xae); 41 write_reg(par, 0xa1); 42 write_reg(par, 0x00); 43 write_reg(par, 0xa8); 44 write_reg(par, 0x3f); 45 write_reg(par, 0xa0); 46 write_reg(par, 0x45); 47 write_reg(par, 0xa2); 48 write_reg(par, 0x40); 49 write_reg(par, 0x75); 50 write_reg(par, 0x00); 51 write_reg(par, 0x3f); 52 write_reg(par, 0x15); 53 write_reg(par, 0x00); 54 write_reg(par, 0x7f); 55 write_reg(par, 0xa4); 56 write_reg(par, 0xaf); 57 58 return 0; 59} 60 61static uint8_t rgb565_to_g16(u16 pixel) 62{ 63 u16 b = pixel & 0x1f; 64 u16 g = (pixel & (0x3f << 5)) >> 5; 65 u16 r = (pixel & (0x1f << (5 + 6))) >> (5 + 6); 66 67 pixel = (299 * r + 587 * g + 114 * b) / 195; 68 if (pixel > 255) 69 pixel = 255; 70 return (uint8_t)pixel / 16; 71} 72 73static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye) 74{ 75 fbtft_par_dbg(DEBUG_SET_ADDR_WIN, par, 76 "%s(xs=%d, ys=%d, xe=%d, ye=%d)\n", __func__, xs, ys, xe, 77 ye); 78 79 write_reg(par, 0x75); 80 write_reg(par, 0x00); 81 write_reg(par, 0x3f); 82 write_reg(par, 0x15); 83 write_reg(par, 0x00); 84 write_reg(par, 0x7f); 85} 86 87static int blank(struct fbtft_par *par, bool on) 88{ 89 fbtft_par_dbg(DEBUG_BLANK, par, "(%s=%s)\n", 90 __func__, on ? "true" : "false"); 91 92 if (on) 93 write_reg(par, 0xAE); 94 else 95 write_reg(par, 0xAF); 96 return 0; 97} 98 99/* 100 * Grayscale Lookup Table 101 * GS1 - GS15 102 * The "Gamma curve" contains the relative values between the entries 103 * in the Lookup table. 104 * 105 * 0 = Setting of GS1 < Setting of GS2 < Setting of GS3.....< 106 * Setting of GS14 < Setting of GS15 107 */ 108static int set_gamma(struct fbtft_par *par, u32 *curves) 109{ 110 int i; 111 112 fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__); 113 114 for (i = 0; i < GAMMA_LEN; i++) { 115 if (i > 0 && curves[i] < 1) { 116 dev_err(par->info->device, 117 "Illegal value in Grayscale Lookup Table at index %d.\n" 118 "Must be greater than 0\n", i); 119 return -EINVAL; 120 } 121 if (curves[i] > 7) { 122 dev_err(par->info->device, 123 "Illegal value(s) in Grayscale Lookup Table.\n" 124 "At index=%d, the accumulated value has exceeded 7\n", 125 i); 126 return -EINVAL; 127 } 128 } 129 write_reg(par, 0xB8); 130 for (i = 0; i < 8; i++) 131 write_reg(par, (curves[i] & 0xFF)); 132 return 0; 133} 134 135static int write_vmem(struct fbtft_par *par, size_t offset, size_t len) 136{ 137 u16 *vmem16 = (u16 *)par->info->screen_buffer; 138 u8 *buf = par->txbuf.buf; 139 u8 n1; 140 u8 n2; 141 int y, x; 142 int ret; 143 144 for (x = 0; x < par->info->var.xres; x++) { 145 if (x % 2) 146 continue; 147 for (y = 0; y < par->info->var.yres; y++) { 148 n1 = rgb565_to_g16(vmem16[y * par->info->var.xres + x]); 149 n2 = rgb565_to_g16(vmem16 150 [y * par->info->var.xres + x + 1]); 151 *buf = (n1 << 4) | n2; 152 buf++; 153 } 154 } 155 156 gpiod_set_value(par->gpio.dc, 1); 157 158 /* Write data */ 159 ret = par->fbtftops.write(par, par->txbuf.buf, 160 par->info->var.xres * par->info->var.yres / 2); 161 if (ret < 0) 162 dev_err(par->info->device, 163 "%s: write failed and returned: %d\n", __func__, ret); 164 165 return ret; 166} 167 168static struct fbtft_display display = { 169 .regwidth = 8, 170 .width = WIDTH, 171 .height = HEIGHT, 172 .txbuflen = WIDTH * HEIGHT / 2, 173 .gamma_num = GAMMA_NUM, 174 .gamma_len = GAMMA_LEN, 175 .gamma = DEFAULT_GAMMA, 176 .fbtftops = { 177 .write_vmem = write_vmem, 178 .init_display = init_display, 179 .set_addr_win = set_addr_win, 180 .blank = blank, 181 .set_gamma = set_gamma, 182 }, 183}; 184 185FBTFT_REGISTER_DRIVER(DRVNAME, "solomon,ssd1325", &display); 186 187MODULE_ALIAS("spi:" DRVNAME); 188MODULE_ALIAS("platform:" DRVNAME); 189MODULE_ALIAS("spi:ssd1325"); 190MODULE_ALIAS("platform:ssd1325"); 191 192MODULE_DESCRIPTION("SSD1325 OLED Driver"); 193MODULE_AUTHOR("Alexey Mednyy"); 194MODULE_LICENSE("GPL");