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	fbtft_par_dbg(DEBUG_BLANK, par, "(%s=%s)\n",
92		      __func__, on ? "true" : "false");
93
94	write_reg(par, on ? 0xAE : 0xAF);
95
96	return 0;
97}
98
99/* Gamma is used to control Contrast */
100static int set_gamma(struct fbtft_par *par, u32 *curves)
101{
102	/* apply mask */
103	curves[0] &= 0xFF;
104
105	/* Set Contrast Control for BANK0 */
106	write_reg(par, 0x81, curves[0]);
107
108	return 0;
109}
110
111static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
112{
113	u16 *vmem16 = (u16 *)par->info->screen_buffer;
114	u32 xres = par->info->var.xres;
115	int page, page_start, page_end, x, i, ret;
116	u8 *buf = par->txbuf.buf;
117
118	/* offset refers to vmem with 2 bytes element size */
119	page_start = offset / (8 * 2 * xres);
120	page_end = DIV_ROUND_UP(offset + len, 8 * 2 * xres);
121
122	for (page = page_start; page < page_end; page++) {
123		/* set page and set column to 2 because of vidmem width 132 */
124		write_reg(par, 0xb0 | page, 0x00 | 2, 0x10 | 0);
125
126		memset(buf, 0, xres);
127		for (x = 0; x < xres; x++)
128			for (i = 0; i < 8; i++)
129				if (vmem16[(page * 8 + i) * xres + x])
130					buf[x] |= BIT(i);
131
132		/* Write data */
133		ret = fbtft_write_buf_dc(par, buf, xres, 1);
134		if (ret < 0)
135			return ret;
136	}
137
138	return 0;
139}
140
141static void write_register(struct fbtft_par *par, int len, ...)
142{
143	va_list args;
144	int i;
145
146	va_start(args, len);
147
148	for (i = 0; i < len; i++)
149		par->buf[i] = va_arg(args, unsigned int);
150
151	/* keep DC low for all command bytes to transfer */
152	fbtft_write_buf_dc(par, par->buf, len, 0);
153
154	va_end(args);
155}
156
157static struct fbtft_display display = {
158	.regwidth = 8,
159	.width = WIDTH,
160	.height = HEIGHT,
161	.txbuflen = WIDTH,
162	.gamma_num = 1,
163	.gamma_len = 1,
164	/* set default contrast to 0xcd = 80% */
165	.gamma = "cd",
166	.fbtftops = {
167		.write_vmem = write_vmem,
168		.write_register = write_register,
169		.init_display = init_display,
170		.set_addr_win = set_addr_win,
171		.blank = blank,
172		.set_gamma = set_gamma,
173	},
174};
175
176FBTFT_REGISTER_SPI_DRIVER(DRVNAME, "sinowealth", "sh1106", &display);
177
178MODULE_DESCRIPTION("SH1106 OLED Driver");
179MODULE_AUTHOR("Heiner Kallweit");
180MODULE_LICENSE("GPL");
181