fb_ssd1331b.c

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/gpio.h>
#include <linux/spi/spi.h>
#include <linux/delay.h>

#include "fbtft.h"

#define DRVNAME		"fb_ssd1331b"
#define WIDTH		96
#define EYEHEIGHT	64
#define TOTALHEIGHT	(EYEHEIGHT*2)
#define EYEBOUNDARY	(WIDTH*EYEHEIGHT*2) // *2 because of 16bpp
#define GAMMA_NUM	1
#define GAMMA_LEN	63
#define DEFAULT_GAMMA	"0 2 2 2 2 2 2 2 " \
			"2 2 2 2 2 2 2 2 " \
			"2 2 2 2 2 2 2 2 " \
			"2 2 2 2 2 2 2 2 " \
			"2 2 2 2 2 2 2 2 " \
			"2 2 2 2 2 2 2 2 " \
			"2 2 2 2 2 2 2 2 " \
			"2 2 2 2 2 2 2" \

/**
 * FIXME: The pinout for this module is currently hard-coded.
 * This module supports a single framebuffer device for two SSD1331 displays,
 * configured in above/below position. The pinouts for each are configured
 * below.
 */
// Left display
#define SSD1331_GPIO_CE0	8
#define SSD1331_GPIO_RST0	24
#define SSD1331_GPIO_DC0	25
// Right display
#define SSD1331_GPIO_CE1	7
#define SSD1331_GPIO_RST1	22
#define SSD1331_GPIO_DC1	23

static struct gpio ssd1331_gpios[] = {
	{ SSD1331_GPIO_CE0, GPIOF_OUT_INIT_HIGH, "CE0" },
	{ SSD1331_GPIO_RST0, GPIOF_OUT_INIT_HIGH, "RST0" },
	{ SSD1331_GPIO_DC0, GPIOF_OUT_INIT_LOW, "DC0" },
	{ SSD1331_GPIO_CE1, GPIOF_OUT_INIT_HIGH, "CE1" },
	{ SSD1331_GPIO_RST1, GPIOF_OUT_INIT_HIGH, "RST1" },
	{ SSD1331_GPIO_DC1, GPIOF_OUT_INIT_LOW, "DC1" },
};

static int init_display(struct fbtft_par *par)
{
	fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);

	par->fbtftops.reset(par);

	write_reg(par, 0xae); /* Display Off */
	write_reg(par, 0xa0, 0x70 | (par->bgr << 2)); /* Set Colour Depth */
	write_reg(par, 0x72); // RGB colour
	write_reg(par, 0xa1, 0x00); /* Set Display Start Line */
	write_reg(par, 0xa2, 0x00); /* Set Display Offset */
	write_reg(par, 0xa4); /* NORMALDISPLAY */
	write_reg(par, 0xa8, 0x3f); // Set multiplex
	write_reg(par, 0xad, 0x8e); // Set master
	// write_reg(par, 0xb0, 0x0b); // Set power mode
	write_reg(par, 0xb1, 0x31); // Precharge
	write_reg(par, 0xb3, 0xf0); // Clock div
	write_reg(par, 0x8a, 0x64); // Precharge A
	write_reg(par, 0x8b, 0x78); // Precharge B
	write_reg(par, 0x8c, 0x64); // Precharge C
	write_reg(par, 0xbb, 0x3a); // Precharge level
	write_reg(par, 0xbe, 0x3e); // vcomh
	write_reg(par, 0x87, 0x06); // Master current
	write_reg(par, 0x81, 0x91); // Contrast A
	write_reg(par, 0x82, 0x50); // Contrast B
	write_reg(par, 0x83, 0x7d); // Contrast C
	write_reg(par, 0xaf); /* Set Sleep Mode Display On */

	return 0;
}

void reset(struct fbtft_par *par)
{
	fbtft_par_dbg(DEBUG_RESET, par, "%s()\n", __func__);
	gpio_set_value(SSD1331_GPIO_RST0, 0);
	gpio_set_value(SSD1331_GPIO_RST1, 0);
	udelay(20);
	gpio_set_value(SSD1331_GPIO_RST0, 1);
	gpio_set_value(SSD1331_GPIO_RST1, 1);
	mdelay(120);
}

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);

	write_reg(par, 0x15, xs, xe);
	write_reg(par, 0x75, ys%EYEHEIGHT, ye%EYEHEIGHT);
}

static void write_reg8_bus8(struct fbtft_par *par, int len, ...)
{
	va_list args;
	int i, ret;
	u8 *buf = (u8 *)par->buf;

	if (unlikely(par->debug & DEBUG_WRITE_REGISTER)) {
		va_start(args, len);
		for (i = 0; i < len; i++) {
			buf[i] = (u8)va_arg(args, unsigned int);
		}
		va_end(args);
		fbtft_par_dbg_hex(DEBUG_WRITE_REGISTER, par, par->info->device, u8, buf, len, "%s: ", __func__);
	}

	va_start(args, len);

	*buf = (u8)va_arg(args, unsigned int);

	gpio_set_value(SSD1331_GPIO_DC0, 0);
	gpio_set_value(SSD1331_GPIO_DC1, 0);

	gpio_set_value(SSD1331_GPIO_CE0, 0);
	gpio_set_value(SSD1331_GPIO_CE1, 0);

	ret = par->fbtftops.write(par, par->buf, sizeof(u8));
	if (ret < 0) {
		va_end(args);
		dev_err(par->info->device, "%s: write() failed and returned %d\n", __func__, ret);
		return;
	}
	len--;

	if (len) {
		i = len;
		while (i--) {
			*buf++ = (u8)va_arg(args, unsigned int);
		}
		ret = par->fbtftops.write(par, par->buf, len * (sizeof(u8)));
		if (ret < 0) {
			va_end(args);
			dev_err(par->info->device, "%s: write() failed and returned %d\n", __func__, ret);
			return;
		}
	}

	gpio_set_value(SSD1331_GPIO_CE0, 1);
	gpio_set_value(SSD1331_GPIO_CE1, 1);

	va_end(args);
}

int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
{
	int ret=0;

	if (offset<EYEBOUNDARY && offset+len<=EYEBOUNDARY) {
		// Entirely on display 0
		gpio_set_value(SSD1331_GPIO_CE0, 0);
		gpio_set_value(SSD1331_GPIO_DC0, 1);
		ret = fbtft_write_vmem16_bus8(par, offset, len);
		gpio_set_value(SSD1331_GPIO_CE0, 1);
	} else if (offset >= EYEBOUNDARY) {
		// Entirely on display 1
		gpio_set_value(SSD1331_GPIO_CE1, 0);
		gpio_set_value(SSD1331_GPIO_DC1, 1);
		ret = fbtft_write_vmem16_bus8(par, offset, len);
		gpio_set_value(SSD1331_GPIO_CE1, 1);
	} else {
		// Starts on display 0, spans to display 1
		gpio_set_value(SSD1331_GPIO_CE0, 0);
		gpio_set_value(SSD1331_GPIO_DC0, 1);
		fbtft_write_vmem16_bus8(par, offset, EYEBOUNDARY-offset);
		gpio_set_value(SSD1331_GPIO_CE0, 1);

		gpio_set_value(SSD1331_GPIO_CE1, 0);
		gpio_set_value(SSD1331_GPIO_DC1, 1);
		ret = fbtft_write_vmem16_bus8(par, EYEBOUNDARY, len+offset-EYEBOUNDARY);
		gpio_set_value(SSD1331_GPIO_CE1, 1);
	}

	return ret;
}

/*
	Grayscale Lookup Table
	GS1 - GS63
	The driver Gamma curve contains the relative values between the entries
	in the Lookup table.

	From datasheet:
	8.8 Gray Scale Decoder

		there are total 180 Gamma Settings (Setting 0 to Setting 180)
		available for the Gray Scale table.

		The gray scale is defined in incremental way, with reference
		to the length of previous table entry:
			Setting of GS1 has to be >= 0
			Setting of GS2 has to be > Setting of GS1 +1
			Setting of GS3 has to be > Setting of GS2 +1
			:
			Setting of GS63 has to be > Setting of GS62 +1


*/
static int set_gamma(struct fbtft_par *par, unsigned long *curves)
{
	unsigned long tmp[GAMMA_NUM * GAMMA_LEN];
	int i, acc = 0;

	fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);

	for (i = 0; i < 63; i++) {
		if (i > 0 && curves[i] < 2) {
			dev_err(par->info->device,
				"Illegal value in Grayscale Lookup Table at index %d. " \
				"Must be greater than 1\n", i);
			return -EINVAL;
		}
		acc += curves[i];
		tmp[i] = acc;
		if (acc > 180) {
			dev_err(par->info->device,
				"Illegal value(s) in Grayscale Lookup Table. " \
				"At index=%d, the accumulated value has exceeded 180\n", i);
			return -EINVAL;
		}
	}

	write_reg(par, 0xB8,
	tmp[0], tmp[1], tmp[2], tmp[3], tmp[4], tmp[5], tmp[6], tmp[7],
	tmp[8], tmp[9], tmp[10], tmp[11], tmp[12], tmp[13], tmp[14], tmp[15],
	tmp[16], tmp[17], tmp[18], tmp[19], tmp[20], tmp[21], tmp[22], tmp[23],
	tmp[24], tmp[25], tmp[26], tmp[27], tmp[28], tmp[29], tmp[30], tmp[31],
	tmp[32], tmp[33], tmp[34], tmp[35], tmp[36], tmp[37], tmp[38], tmp[39],
	tmp[40], tmp[41], tmp[42], tmp[43], tmp[44], tmp[45], tmp[46], tmp[47],
	tmp[48], tmp[49], tmp[50], tmp[51], tmp[52], tmp[53], tmp[54], tmp[55],
	tmp[56], tmp[57], tmp[58], tmp[59], tmp[60], tmp[61], tmp[62]);

	return 0;
}

static int blank(struct fbtft_par *par, bool on)
{
	fbtft_par_dbg(DEBUG_BLANK, par, "%s(blank=%s)\n",
		__func__, on ? "true" : "false");

	gpio_set_value(SSD1331_GPIO_CE0, 0);
	gpio_set_value(SSD1331_GPIO_CE1, 0);

	if (on)
		write_reg(par, 0xAE);
	else
		write_reg(par, 0xAF);

	gpio_set_value(SSD1331_GPIO_CE0, 1);
	gpio_set_value(SSD1331_GPIO_CE1, 1);
	return 0;
}

int request_gpios(struct fbtft_par *par)
{
	int i;
	int ret;

	/* Initialize gpios to disabled */
	par->gpio.reset = -1;
	par->gpio.dc = -1;
	par->gpio.rd = -1;
	par->gpio.wr = -1;
	par->gpio.cs = -1;
	par->gpio.latch = -1;
	for (i = 0; i < 16; i++) {
		par->gpio.db[i] = -1;
		par->gpio.led[i] = -1;
		par->gpio.aux[i] = -1;
	}

	ret = gpio_request_array(ssd1331_gpios, ARRAY_SIZE(ssd1331_gpios));
	if (ret) {
		dev_err(par->info->device,
			"%s: gpio_request_array(...) failed with %d\n",
			__func__, ret);
		return ret;
	}

	return 0;
}

int verify_gpios(struct fbtft_par *par)
{
	return 0;
}

void free_gpios(struct fbtft_par *par)
{
	fbtft_par_dbg(DEBUG_FREE_GPIOS, par, "%s()\n", __func__);
	gpio_free_array(ssd1331_gpios, ARRAY_SIZE(ssd1331_gpios));
}

static struct fbtft_display display = {
	.regwidth = 8,
	.width = WIDTH,
	.height = TOTALHEIGHT,
	.gamma_num = GAMMA_NUM,
	.gamma_len = GAMMA_LEN,
	.gamma = DEFAULT_GAMMA,
	.fbtftops = {
		.init_display = init_display,
		.reset = reset,
		.request_gpios = request_gpios,
		.verify_gpios = verify_gpios,
		.write_register = write_reg8_bus8,
		.set_addr_win = set_addr_win,
		.set_gamma = set_gamma,
		.blank = blank,
		.write_vmem = write_vmem,
		.free_gpios = free_gpios,
	},
};

FBTFT_REGISTER_DRIVER(DRVNAME, &display);

MODULE_ALIAS("spi:" DRVNAME);
MODULE_ALIAS("platform:" DRVNAME);

MODULE_DESCRIPTION("Dual SSD1331 Binocular OLED Driver");
MODULE_AUTHOR("Alec Smecher (adapted from SSD1351 by James Davies)");
MODULE_LICENSE("GPL");