fb_sh1106.c

  1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * FB driver for the SH1106 OLED Controller
  4 * Based on the SSD1306 driver by Noralf Tronnes
  5 *
  6 * Copyright (C) 2017 Heiner Kallweit
  7 */
  8
  9#include <linux/module.h>
 10#include <linux/kernel.h>
 11#include <linux/init.h>
 12#include <linux/delay.h>
 13
 14#include "fbtft.h"
 15
 16#define DRVNAME		"fb_sh1106"
 17#define WIDTH		128
 18#define HEIGHT		64
 19
 20/* Init sequence based on the Adafruit SSD1306 Arduino library */
 21static int init_display(struct fbtft_par *par)
 22{
 23	if (!par->info->var.xres || par->info->var.xres > WIDTH ||
 24	    !par->info->var.yres || par->info->var.yres > HEIGHT ||
 25	    par->info->var.yres % 8) {
 26		dev_err(par->info->device, "Invalid screen size\n");
 27		return -EINVAL;
 28	}
 29
 30	if (par->info->var.rotate) {
 31		dev_err(par->info->device, "Display rotation not supported\n");
 32		return -EINVAL;
 33	}
 34
 35	par->fbtftops.reset(par);
 36
 37	/* Set Display OFF */
 38	write_reg(par, 0xAE);
 39
 40	/* Set Display Clock Divide Ratio/ Oscillator Frequency */
 41	write_reg(par, 0xD5, 0x80);
 42
 43	/* Set Multiplex Ratio */
 44	write_reg(par, 0xA8, par->info->var.yres - 1);
 45
 46	/* Set Display Offset */
 47	write_reg(par, 0xD3, 0x00);
 48
 49	/* Set Display Start Line */
 50	write_reg(par, 0x40 | 0x0);
 51
 52	/* Set Segment Re-map */
 53	/* column address 127 is mapped to SEG0 */
 54	write_reg(par, 0xA0 | 0x1);
 55
 56	/* Set COM Output Scan Direction */
 57	/* remapped mode. Scan from COM[N-1] to COM0 */
 58	write_reg(par, 0xC8);
 59
 60	/* Set COM Pins Hardware Configuration */
 61	if (par->info->var.yres == 64)
 62		/* A[4]=1b, Alternative COM pin configuration */
 63		write_reg(par, 0xDA, 0x12);
 64	else if (par->info->var.yres == 48)
 65		/* A[4]=1b, Alternative COM pin configuration */
 66		write_reg(par, 0xDA, 0x12);
 67	else
 68		/* A[4]=0b, Sequential COM pin configuration */
 69		write_reg(par, 0xDA, 0x02);
 70
 71	/* Set Pre-charge Period */
 72	write_reg(par, 0xD9, 0xF1);
 73
 74	/* Set VCOMH Deselect Level */
 75	write_reg(par, 0xDB, 0x40);
 76
 77	/* Set Display ON */
 78	write_reg(par, 0xAF);
 79
 80	msleep(150);
 81
 82	return 0;
 83}
 84
 85static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
 86{
 87}
 88
 89static int blank(struct fbtft_par *par, bool on)
 90{
 91	write_reg(par, on ? 0xAE : 0xAF);
 92
 93	return 0;
 94}
 95
 96/* Gamma is used to control Contrast */
 97static int set_gamma(struct fbtft_par *par, u32 *curves)
 98{
 99	/* apply mask */
100	curves[0] &= 0xFF;
101
102	/* Set Contrast Control for BANK0 */
103	write_reg(par, 0x81, curves[0]);
104
105	return 0;
106}
107
108static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
109{
110	u16 *vmem16 = (u16 *)par->info->screen_buffer;
111	u32 xres = par->info->var.xres;
112	int page, page_start, page_end, x, i, ret;
113	u8 *buf = par->txbuf.buf;
114
115	/* offset refers to vmem with 2 bytes element size */
116	page_start = offset / (8 * 2 * xres);
117	page_end = DIV_ROUND_UP(offset + len, 8 * 2 * xres);
118
119	for (page = page_start; page < page_end; page++) {
120		/* set page and set column to 2 because of vidmem width 132 */
121		write_reg(par, 0xb0 | page, 0x00 | 2, 0x10 | 0);
122
123		memset(buf, 0, xres);
124		for (x = 0; x < xres; x++)
125			for (i = 0; i < 8; i++)
126				if (vmem16[(page * 8 + i) * xres + x])
127					buf[x] |= BIT(i);
128
129		/* Write data */
130		ret = fbtft_write_buf_dc(par, buf, xres, 1);
131		if (ret < 0)
132			return ret;
133	}
134
135	return 0;
136}
137
138static void write_register(struct fbtft_par *par, int len, ...)
139{
140	va_list args;
141	int i;
142
143	va_start(args, len);
144
145	for (i = 0; i < len; i++)
146		par->buf[i] = va_arg(args, unsigned int);
147
148	/* keep DC low for all command bytes to transfer */
149	fbtft_write_buf_dc(par, par->buf, len, 0);
150
151	va_end(args);
152}
153
154static struct fbtft_display display = {
155	.regwidth = 8,
156	.width = WIDTH,
157	.height = HEIGHT,
158	.txbuflen = WIDTH,
159	.gamma_num = 1,
160	.gamma_len = 1,
161	/* set default contrast to 0xcd = 80% */
162	.gamma = "cd",
163	.fbtftops = {
164		.write_vmem = write_vmem,
165		.write_register = write_register,
166		.init_display = init_display,
167		.set_addr_win = set_addr_win,
168		.blank = blank,
169		.set_gamma = set_gamma,
170	},
171};
172
173FBTFT_REGISTER_SPI_DRIVER(DRVNAME, "sinowealth", "sh1106", &display);
174
175MODULE_DESCRIPTION("SH1106 OLED Driver");
176MODULE_AUTHOR("Heiner Kallweit");
177MODULE_LICENSE("GPL");