staging: fbtft: add fb_ssd1331 driver

This commit adds the fb_ssd1331 driver from the fbtft project at
https://github.com/notro/fbtft.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Noralf Tronnes <notro@tronnes.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fbtft/Kconfig

@@ -109,3 +109,9 @@ config FB_TFT_SSD1306
 	depends on FB_TFT
 	help
 	  Framebuffer support for SSD1306
+
+config FB_TFT_SSD1331
+	tristate "FB driver for the SSD1331 LCD Controller"
+	depends on FB_TFT
+	help
+	  Framebuffer support for SSD1331

drivers/staging/fbtft/Makefile

@@ -20,3 +20,4 @@ obj-$(CONFIG_FB_TFT_S6D02A1)     += fb_s6d02a1.o
 obj-$(CONFIG_FB_TFT_S6D1121)     += fb_s6d1121.o
 obj-$(CONFIG_FB_TFT_SSD1289)     += fb_ssd1289.o
 obj-$(CONFIG_FB_TFT_SSD1306)     += fb_ssd1306.o
+obj-$(CONFIG_FB_TFT_SSD1331)     += fb_ssd1331.o

drivers/staging/fbtft/fb_ssd1331.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_ssd1331"
+#define WIDTH		96
+#define HEIGHT		64
+#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" \
+
+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;
+}
+
+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, ye);
+}
+
+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);
+	if (par->gpio.dc != -1)
+		gpio_set_value(par->gpio.dc, 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;
+		}
+	}
+	if (par->gpio.dc != -1)
+		gpio_set_value(par->gpio.dc, 1);
+	va_end(args);
+}
+
+/*
+	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");
+	if (on)
+		write_reg(par, 0xAE);
+	else
+		write_reg(par, 0xAF);
+	return 0;
+}
+
+
+static struct fbtft_display display = {
+	.regwidth = 8,
+	.width = WIDTH,
+	.height = HEIGHT,
+	.gamma_num = GAMMA_NUM,
+	.gamma_len = GAMMA_LEN,
+	.gamma = DEFAULT_GAMMA,
+	.fbtftops = {
+		.write_register = write_reg8_bus8,
+		.init_display = init_display,
+		.set_addr_win = set_addr_win,
+		.set_gamma = set_gamma,
+		.blank = blank,
+	},
+};
+
+FBTFT_REGISTER_DRIVER(DRVNAME, "solomon,ssd1331", &display);
+
+MODULE_ALIAS("spi:" DRVNAME);
+MODULE_ALIAS("platform:" DRVNAME);
+MODULE_ALIAS("spi:ssd1331");
+MODULE_ALIAS("platform:ssd1331");
+
+MODULE_DESCRIPTION("SSD1331 OLED Driver");
+MODULE_AUTHOR("Alec Smecher (adapted from SSD1351 by James Davies)");
+MODULE_LICENSE("GPL");