1 // SPDX-License-Identifier: GPL-2.0+
3 * FB driver for the SSD1306 OLED Controller
5 * Copyright (C) 2013 Noralf Tronnes
8 #include <linux/module.h>
9 #include <linux/kernel.h>
10 #include <linux/init.h>
11 #include <linux/gpio/consumer.h>
12 #include <linux/delay.h>
16 #define DRVNAME "fb_ssd1306"
23 * This doesn't work because D/C has to be LOW for both values:
24 * write_reg(par, val1, val2);
27 * write_reg(par, val1);
28 * write_reg(par, val2);
31 /* Init sequence taken from the Adafruit SSD1306 Arduino library */
32 static int init_display(struct fbtft_par *par)
34 par->fbtftops.reset(par);
36 if (par->gamma.curves[0] == 0) {
37 mutex_lock(&par->gamma.lock);
38 if (par->info->var.yres == 64)
39 par->gamma.curves[0] = 0xCF;
41 par->gamma.curves[0] = 0x8F;
42 mutex_unlock(&par->gamma.lock);
48 /* Set Display Clock Divide Ratio/ Oscillator Frequency */
52 /* Set Multiplex Ratio */
54 if (par->info->var.yres == 64)
56 else if (par->info->var.yres == 48)
61 /* Set Display Offset */
65 /* Set Display Start Line */
66 write_reg(par, 0x40 | 0x0);
68 /* Charge Pump Setting */
70 /* A[2] = 1b, Enable charge pump during display on */
73 /* Set Memory Addressing Mode */
75 /* Vertical addressing mode */
78 /* Set Segment Re-map */
79 /* column address 127 is mapped to SEG0 */
80 write_reg(par, 0xA0 | 0x1);
82 /* Set COM Output Scan Direction */
83 /* remapped mode. Scan from COM[N-1] to COM0 */
86 /* Set COM Pins Hardware Configuration */
88 if (par->info->var.yres == 64)
89 /* A[4]=1b, Alternative COM pin configuration */
91 else if (par->info->var.yres == 48)
92 /* A[4]=1b, Alternative COM pin configuration */
95 /* A[4]=0b, Sequential COM pin configuration */
98 /* Set Pre-charge Period */
100 write_reg(par, 0xF1);
102 /* Set VCOMH Deselect Level */
103 write_reg(par, 0xDB);
104 /* according to the datasheet, this value is out of bounds */
105 write_reg(par, 0x40);
107 /* Entire Display ON */
108 /* Resume to RAM content display. Output follows RAM content */
109 write_reg(par, 0xA4);
111 /* Set Normal Display
112 * 0 in RAM: OFF in display panel
113 * 1 in RAM: ON in display panel
115 write_reg(par, 0xA6);
118 write_reg(par, 0xAF);
123 static void set_addr_win_64x48(struct fbtft_par *par)
125 /* Set Column Address */
126 write_reg(par, 0x21);
127 write_reg(par, 0x20);
128 write_reg(par, 0x5F);
130 /* Set Page Address */
131 write_reg(par, 0x22);
136 static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
138 /* Set Lower Column Start Address for Page Addressing Mode */
139 write_reg(par, 0x00 | 0x0);
140 /* Set Higher Column Start Address for Page Addressing Mode */
141 write_reg(par, 0x10 | 0x0);
142 /* Set Display Start Line */
143 write_reg(par, 0x40 | 0x0);
145 if (par->info->var.xres == 64 && par->info->var.yres == 48)
146 set_addr_win_64x48(par);
149 static int blank(struct fbtft_par *par, bool on)
151 fbtft_par_dbg(DEBUG_BLANK, par, "(%s=%s)\n",
152 __func__, on ? "true" : "false");
155 write_reg(par, 0xAE);
157 write_reg(par, 0xAF);
161 /* Gamma is used to control Contrast */
162 static int set_gamma(struct fbtft_par *par, u32 *curves)
167 /* Set Contrast Control for BANK0 */
168 write_reg(par, 0x81);
169 write_reg(par, curves[0]);
174 static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
176 u16 *vmem16 = (u16 *)par->info->screen_buffer;
177 u32 xres = par->info->var.xres;
178 u32 yres = par->info->var.yres;
179 u8 *buf = par->txbuf.buf;
183 for (x = 0; x < xres; x++) {
184 for (y = 0; y < yres / 8; y++) {
186 for (i = 0; i < 8; i++)
187 if (vmem16[(y * 8 + i) * xres + x])
194 gpiod_set_value(par->gpio.dc, 1);
195 ret = par->fbtftops.write(par, par->txbuf.buf, xres * yres / 8);
197 dev_err(par->info->device, "write failed and returned: %d\n",
203 static struct fbtft_display display = {
211 .write_vmem = write_vmem,
212 .init_display = init_display,
213 .set_addr_win = set_addr_win,
215 .set_gamma = set_gamma,
219 FBTFT_REGISTER_DRIVER(DRVNAME, "solomon,ssd1306", &display);
221 MODULE_ALIAS("spi:" DRVNAME);
222 MODULE_ALIAS("platform:" DRVNAME);
223 MODULE_ALIAS("spi:ssd1306");
224 MODULE_ALIAS("platform:ssd1306");
226 MODULE_DESCRIPTION("SSD1306 OLED Driver");
227 MODULE_AUTHOR("Noralf Tronnes");
228 MODULE_LICENSE("GPL");