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d12b9c1 Aug 16, 2014
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/*
* FB driver for the SSD1306 OLED Controller
*
* Copyright (C) 2013 Noralf Tronnes
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/gpio.h>
#include <linux/delay.h>
#include "fbtft.h"
#define DRVNAME "fb_ssd1306"
#define WIDTH 128
#define HEIGHT 64
/*
write_reg() caveat:
This doesn't work because D/C has to be LOW for both values:
write_reg(par, val1, val2);
Do it like this:
write_reg(par, val1);
write_reg(par, val2);
*/
/* Init sequence taken from the Adafruit SSD1306 Arduino library */
static int init_display(struct fbtft_par *par)
{
fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
par->fbtftops.reset(par);
if (par->gamma.curves[0] == 0) {
mutex_lock(&par->gamma.lock);
if (par->info->var.yres == 64)
par->gamma.curves[0] = 0xCF;
else
par->gamma.curves[0] = 0x8F;
mutex_unlock(&par->gamma.lock);
}
/* Set Display OFF */
write_reg(par, 0xAE);
/* Set Display Clock Divide Ratio/ Oscillator Frequency */
write_reg(par, 0xD5);
write_reg(par, 0x80);
/* Set Multiplex Ratio */
write_reg(par, 0xA8);
if (par->info->var.yres == 64)
write_reg(par, 0x3F);
else
write_reg(par, 0x1F);
/* Set Display Offset */
write_reg(par, 0xD3);
write_reg(par, 0x0);
/* Set Display Start Line */
write_reg(par, 0x40 | 0x0);
/* Charge Pump Setting */
write_reg(par, 0x8D);
/* A[2] = 1b, Enable charge pump during display on */
write_reg(par, 0x14);
/* Set Memory Addressing Mode */
write_reg(par, 0x20);
/* Vertical addressing mode */
write_reg(par, 0x01);
/*Set Segment Re-map */
/* column address 127 is mapped to SEG0 */
write_reg(par, 0xA0 | 0x1);
/* Set COM Output Scan Direction */
/* remapped mode. Scan from COM[N-1] to COM0 */
write_reg(par, 0xC8);
/* Set COM Pins Hardware Configuration */
write_reg(par, 0xDA);
if (par->info->var.yres == 64)
/* A[4]=1b, Alternative COM pin configuration */
write_reg(par, 0x12);
else
/* A[4]=0b, Sequential COM pin configuration */
write_reg(par, 0x02);
/* Set Pre-charge Period */
write_reg(par, 0xD9);
write_reg(par, 0xF1);
/* Set VCOMH Deselect Level */
write_reg(par, 0xDB);
/* according to the datasheet, this value is out of bounds */
write_reg(par, 0x40);
/* Entire Display ON */
/* Resume to RAM content display. Output follows RAM content */
write_reg(par, 0xA4);
/* Set Normal Display
0 in RAM: OFF in display panel
1 in RAM: ON in display panel */
write_reg(par, 0xA6);
/* Set Display ON */
write_reg(par, 0xAF);
return 0;
}
static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
{
fbtft_par_dbg(DEBUG_SET_ADDR_WIN, par,
"%s(xs=%d, ys=%d, xe=%d, ye=%d)\n", __func__, xs, ys, xe, ye);
/* Set Lower Column Start Address for Page Addressing Mode */
write_reg(par, 0x00 | 0x0);
/* Set Higher Column Start Address for Page Addressing Mode */
write_reg(par, 0x10 | 0x0);
/* Set Display Start Line */
write_reg(par, 0x40 | 0x0);
}
static int blank(struct fbtft_par *par, bool on)
{
fbtft_par_dbg(DEBUG_BLANK, par, "%s(blank=%s)\n",
__func__, on ? "true" : "false");
if (on)
write_reg(par, 0xAE);
else
write_reg(par, 0xAF);
return 0;
}
/* Gamma is used to control Contrast */
static int set_gamma(struct fbtft_par *par, unsigned long *curves)
{
fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
/* apply mask */
curves[0] &= 0xFF;
/* Set Contrast Control for BANK0 */
write_reg(par, 0x81);
write_reg(par, curves[0]);
return 0;
}
static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
{
u16 *vmem16 = (u16 *)par->info->screen_base;
u8 *buf = par->txbuf.buf;
int x, y, i;
int ret = 0;
fbtft_par_dbg(DEBUG_WRITE_VMEM, par, "%s()\n", __func__);
for (x = 0; x < par->info->var.xres; x++) {
for (y = 0; y < par->info->var.yres/8; y++) {
*buf = 0x00;
for (i = 0; i < 8; i++)
*buf |= (vmem16[(y*8+i)*par->info->var.xres+x] ? 1 : 0) << i;
buf++;
}
}
/* Write data */
gpio_set_value(par->gpio.dc, 1);
ret = par->fbtftops.write(par, par->txbuf.buf,
par->info->var.xres*par->info->var.yres/8);
if (ret < 0)
dev_err(par->info->device,
"%s: write failed and returned: %d\n", __func__, ret);
return ret;
}
static struct fbtft_display display = {
.regwidth = 8,
.width = WIDTH,
.height = HEIGHT,
.gamma_num = 1,
.gamma_len = 1,
.gamma = "00",
.fbtftops = {
.write_vmem = write_vmem,
.init_display = init_display,
.set_addr_win = set_addr_win,
.blank = blank,
.set_gamma = set_gamma,
},
};
FBTFT_REGISTER_DRIVER(DRVNAME, "solomon,ssd1306", &display);
MODULE_ALIAS("spi:" DRVNAME);
MODULE_ALIAS("platform:" DRVNAME);
MODULE_ALIAS("spi:ssd1306");
MODULE_ALIAS("platform:ssd1306");
MODULE_DESCRIPTION("SSD1306 OLED Driver");
MODULE_AUTHOR("Noralf Tronnes");
MODULE_LICENSE("GPL");