staging: fbtft: add fb_ssd1351 driver

This commit adds the fb_ssd1351 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

@@ -115,3 +115,9 @@ config FB_TFT_SSD1331
 	depends on FB_TFT
 	help
 	  Framebuffer support for SSD1331
+
+config FB_TFT_SSD1351
+	tristate "FB driver for the SSD1351 LCD Controller"
+	depends on FB_TFT
+	help
+	  Framebuffer support for SSD1351

drivers/staging/fbtft/Makefile

@@ -21,3 +21,4 @@ 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
+obj-$(CONFIG_FB_TFT_SSD1351)     += fb_ssd1351.o

drivers/staging/fbtft/fb_ssd1351.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_ssd1351"
+#define WIDTH		128
+#define HEIGHT		128
+#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 void register_onboard_backlight(struct fbtft_par *par);
+
+static int init_display(struct fbtft_par *par)
+{
+	fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
+
+	if (par->pdata
+		&& par->pdata->display.backlight == FBTFT_ONBOARD_BACKLIGHT) {
+		/* module uses onboard GPIO for panel power */
+		par->fbtftops.register_backlight = register_onboard_backlight;
+	}
+
+	par->fbtftops.reset(par);
+
+	write_reg(par, 0xfd, 0x12); /* Command Lock */
+	write_reg(par, 0xfd, 0xb1); /* Command Lock */
+	write_reg(par, 0xae); /* Display Off */
+	write_reg(par, 0xb3, 0xf1); /* Front Clock Div */
+	write_reg(par, 0xca, 0x7f); /* Set Mux Ratio */
+	write_reg(par, 0x15, 0x00, 0x7f); /* Set Column Address */
+	write_reg(par, 0x75, 0x00, 0x7f); /* Set Row Address */
+	write_reg(par, 0xa1, 0x00); /* Set Display Start Line */
+	write_reg(par, 0xa2, 0x00); /* Set Display Offset */
+	write_reg(par, 0xb5, 0x00); /* Set GPIO */
+	write_reg(par, 0xab, 0x01); /* Set Function Selection */
+	write_reg(par, 0xb1, 0x32); /* Set Phase Length */
+	write_reg(par, 0xb4, 0xa0, 0xb5, 0x55); /* Set Segment Low Voltage */
+	write_reg(par, 0xbb, 0x17); /* Set Precharge Voltage */
+	write_reg(par, 0xbe, 0x05); /* Set VComH Voltage */
+	write_reg(par, 0xc1, 0xc8, 0x80, 0xc8); /* Set Contrast */
+	write_reg(par, 0xc7, 0x0f); /* Set Master Contrast */
+	write_reg(par, 0xb6, 0x01); /* Set Second Precharge Period */
+	write_reg(par, 0xa6); /* Set Display Mode Reset */
+	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);
+	write_reg(par, 0x5c);
+}
+
+static int set_var(struct fbtft_par *par)
+{
+	unsigned remap;
+	fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
+
+	if (par->fbtftops.init_display != init_display) {
+		/* don't risk messing up register A0h */
+		fbtft_par_dbg(DEBUG_INIT_DISPLAY, par,
+			"%s: skipping since custom init_display() is used\n",
+			__func__);
+		return 0;
+	}
+
+	remap = 0x60 | (par->bgr << 2); /* Set Colour Depth */
+
+	switch (par->info->var.rotate) {
+	case 0:
+		write_reg(par, 0xA0, remap | 0b00 | 1<<4);
+		break;
+	case 270:
+		write_reg(par, 0xA0, remap | 0b11 | 1<<4);
+		break;
+	case 180:
+		write_reg(par, 0xA0, remap | 0b10);
+		break;
+	case 90:
+		write_reg(par, 0xA0, remap | 0b01);
+		break;
+	}
+
+	return 0;
+}
+
+/*
+	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 = {
+		.init_display = init_display,
+		.set_addr_win = set_addr_win,
+		.set_var = set_var,
+		.set_gamma = set_gamma,
+		.blank = blank,
+	},
+};
+
+#ifdef CONFIG_FB_BACKLIGHT
+static int update_onboard_backlight(struct backlight_device *bd)
+{
+	struct fbtft_par *par = bl_get_data(bd);
+	bool on;
+
+	fbtft_par_dbg(DEBUG_BACKLIGHT, par,
+		"%s: power=%d, fb_blank=%d\n",
+		__func__, bd->props.power, bd->props.fb_blank);
+
+	on = (bd->props.power == FB_BLANK_UNBLANK)
+		&& (bd->props.fb_blank == FB_BLANK_UNBLANK);
+	/* Onboard backlight connected to GPIO0 on SSD1351, GPIO1 unused */
+	write_reg(par, 0xB5, on ? 0x03 : 0x02);
+
+	return 0;
+}
+
+static void register_onboard_backlight(struct fbtft_par *par)
+{
+	struct backlight_device *bd;
+	struct backlight_properties bl_props = { 0, };
+	struct backlight_ops *bl_ops;
+
+	fbtft_par_dbg(DEBUG_BACKLIGHT, par, "%s()\n", __func__);
+
+	bl_ops = devm_kzalloc(par->info->device, sizeof(struct backlight_ops),
+				GFP_KERNEL);
+	if (!bl_ops) {
+		dev_err(par->info->device,
+			"%s: could not allocate memory for backlight operations.\n",
+			__func__);
+		return;
+	}
+
+	bl_ops->update_status = update_onboard_backlight;
+	bl_props.type = BACKLIGHT_RAW;
+	bl_props.power = FB_BLANK_POWERDOWN;
+
+	bd = backlight_device_register(dev_driver_string(par->info->device),
+				par->info->device, par, bl_ops, &bl_props);
+	if (IS_ERR(bd)) {
+		dev_err(par->info->device,
+			"cannot register backlight device (%ld)\n",
+			PTR_ERR(bd));
+		return;
+	}
+	par->info->bl_dev = bd;
+
+	if (!par->fbtftops.unregister_backlight)
+		par->fbtftops.unregister_backlight = fbtft_unregister_backlight;
+}
+#else
+static void register_onboard_backlight(struct fbtft_par *par) { };
+#endif
+
+
+FBTFT_REGISTER_DRIVER(DRVNAME, "solomon,ssd1351", &display);
+
+MODULE_ALIAS("spi:" DRVNAME);
+MODULE_ALIAS("platform:" DRVNAME);
+MODULE_ALIAS("spi:ssd1351");
+MODULE_ALIAS("platform:ssd1351");
+
+MODULE_DESCRIPTION("SSD1351 OLED Driver");
+MODULE_AUTHOR("James Davies");
+MODULE_LICENSE("GPL");