staging: fbtft: add support for ST7789V display controller

This patch adds support for the Sitronix ST7789V display controller.
The controller is intended for small color displays with a resolution
of up to 320x240 pixels.
Signed-off-by: Dennis Menschel <menschel-d@posteo.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fbtft/Kconfig

@@ -141,6 +141,16 @@ config FB_TFT_ST7735R
 	help
 	  Generic Framebuffer support for ST7735R
 
+config FB_TFT_ST7789V
+	tristate "FB driver for the ST7789V LCD Controller"
+	depends on FB_TFT
+	help
+	  This enables generic framebuffer support for the Sitronix ST7789V
+	  display controller. The controller is intended for small color
+	  displays with a resolution of up to 320x240 pixels.
+
+	  Say Y if you have such a display that utilizes this controller.
+
 config FB_TFT_TINYLCD
 	tristate "FB driver for tinylcd.com display"
 	depends on FB_TFT

drivers/staging/fbtft/Makefile

@@ -25,6 +25,7 @@ obj-$(CONFIG_FB_TFT_SSD1306)     += fb_ssd1306.o
 obj-$(CONFIG_FB_TFT_SSD1331)     += fb_ssd1331.o
 obj-$(CONFIG_FB_TFT_SSD1351)     += fb_ssd1351.o
 obj-$(CONFIG_FB_TFT_ST7735R)     += fb_st7735r.o
+obj-$(CONFIG_FB_TFT_ST7789V)     += fb_st7789v.o
 obj-$(CONFIG_FB_TFT_TINYLCD)     += fb_tinylcd.o
 obj-$(CONFIG_FB_TFT_TLS8204)     += fb_tls8204.o
 obj-$(CONFIG_FB_TFT_UC1611)      += fb_uc1611.o

drivers/staging/fbtft/fb_st7789v.c

+/*
+ * FB driver for the ST7789V LCD Controller
+ *
+ * Copyright (C) 2015 Dennis Menschel
+ *
+ * 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.
+ */
+
+#include <linux/bitops.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include "fbtft.h"
+
+#define DRVNAME "fb_st7789v"
+
+#define DEFAULT_GAMMA \
+	"70 2C 2E 15 10 09 48 33 53 0B 19 18 20 25\n" \
+	"70 2C 2E 15 10 09 48 33 53 0B 19 18 20 25"
+
+/**
+ * enum st7789v_command - ST7789V display controller commands
+ *
+ * @SLPOUT: sleep out
+ * @DISPOFF: display off
+ * @DISPON: display on
+ * @CASET: column address set
+ * @RASET: row address set
+ * @RAMRW: memory write
+ * @MADCTL: memory data access control
+ * @COLMOD: interface pixel format
+ * @PORCTRL: porch setting
+ * @GCTRL: gate control
+ * @VCOMS: VCOM setting
+ * @VDVVRHEN: VDV and VRH command enable
+ * @VRHS: VRH set
+ * @VDVS: VDV set
+ * @VCMOFSET: VCOM offset set
+ * @PWCTRL1: power control 1
+ * @PVGAMCTRL: positive voltage gamma control
+ * @NVGAMCTRL: negative voltage gamma control
+ *
+ * The command names are the same as those found in the datasheet to ease
+ * looking up their semantics and usage.
+ *
+ * Note that the ST7789V display controller offers quite a few more commands
+ * which have been omitted from this list as they are not used at the moment.
+ */
+enum st7789v_command {
+	SLPOUT = 0x11,
+	DISPOFF = 0x28,
+	DISPON = 0x29,
+	CASET = 0x2A,
+	RASET = 0x2B,
+	RAMRW = 0x2C,
+	MADCTL = 0x36,
+	COLMOD = 0x3A,
+	PORCTRL = 0xB2,
+	GCTRL = 0xB7,
+	VCOMS = 0xBB,
+	VDVVRHEN = 0xC2,
+	VRHS = 0xC3,
+	VDVS = 0xC4,
+	VCMOFSET = 0xC5,
+	PWCTRL1 = 0xD0,
+	PVGAMCTRL = 0xE0,
+	NVGAMCTRL = 0xE1,
+};
+
+#define MADCTL_BGR BIT(3) /* bitmask for RGB/BGR order */
+#define MADCTL_MV BIT(5) /* bitmask for page/column order */
+#define MADCTL_MX BIT(6) /* bitmask for column address order */
+#define MADCTL_MY BIT(7) /* bitmask for page address order */
+
+/**
+ * default_init_sequence - default initialization sequence for ST7789V
+ *
+ * Most of the commands in this init sequence set their parameters to the
+ * same default values which are already in place after the display has been
+ * powered up. (The main exception to this rule is the pixel format which
+ * would default to 18 instead of 16 bit per pixel.)
+ * Nonetheless, this sequence can be used as a template for concrete
+ * displays which usually need some adjustments.
+ */
+static int default_init_sequence[] = {
+	/* turn off sleep mode */
+	-1, SLPOUT,
+	-2, 120,
+
+	/* set pixel format to RGB-565 */
+	-1, COLMOD, 0x05,
+
+	-1, PORCTRL, 0x08, 0x08, 0x00, 0x22, 0x22,
+
+	/*
+	 * VGH = 13.26V
+	 * VGL = -10.43V
+	 */
+	-1, GCTRL, 0x35,
+
+	/*
+	 * VDV and VRH register values come from command write
+	 * (instead of NVM)
+	 */
+	-1, VDVVRHEN, 0x01, 0xFF,
+
+	/*
+	 * VAP =  4.1V + (VCOM + VCOM offset + 0.5 * VDV)
+	 * VAN = -4.1V + (VCOM + VCOM offset + 0.5 * VDV)
+	 */
+	-1, VRHS, 0x0B,
+
+	/* VDV = 0V */
+	-1, VDVS, 0x20,
+
+	/* VCOM = 0.9V */
+	-1, VCOMS, 0x20,
+
+	/* VCOM offset = 0V */
+	-1, VCMOFSET, 0x20,
+
+	/*
+	 * AVDD = 6.8V
+	 * AVCL = -4.8V
+	 * VDS = 2.3V
+	 */
+	-1, PWCTRL1, 0xA4, 0xA1,
+
+	-1, DISPON,
+
+	-3,
+};
+
+/**
+ * set_addr_win() - configure display area to use
+ *
+ * @par: FBTFT parameter object
+ * @xs: first active pixel of x-axis
+ * @ys: first active pixel of y-axis
+ * @xe: last active pixel of x-axis
+ * @ye: last active pixel of y-axis
+ */
+static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
+{
+	write_reg(par, CASET, xs >> 8, xs & 0xFF, xe >> 8, xe & 0xFF);
+	write_reg(par, RASET, ys >> 8, ys & 0xFF, ye >> 8, ye & 0xFF);
+	write_reg(par, RAMRW);
+}
+
+/**
+ * set_var() - apply LCD properties like rotation and BGR mode
+ *
+ * @par: FBTFT parameter object
+ *
+ * Return: 0 on success, < 0 if error occurred.
+ */
+static int set_var(struct fbtft_par *par)
+{
+	u8 madctl_par = 0;
+
+	if (par->bgr)
+		madctl_par |= MADCTL_BGR;
+	switch (par->info->var.rotate) {
+	case 0:
+		break;
+	case 90:
+		madctl_par |= (MADCTL_MV | MADCTL_MY);
+		break;
+	case 180:
+		madctl_par |= (MADCTL_MX | MADCTL_MY);
+		break;
+	case 270:
+		madctl_par |= (MADCTL_MV | MADCTL_MX);
+		break;
+	default:
+		return -EINVAL;
+	}
+	write_reg(par, MADCTL, madctl_par);
+	return 0;
+}
+
+/**
+ * set_gamma() - set gamma curves
+ *
+ * @par: FBTFT parameter object
+ * @curves: gamma curves
+ *
+ * Before the gamma curves are applied, they are preprocessed with a bitmask
+ * to ensure syntactically correct input for the display controller.
+ * This implies that the curves input parameter might be changed by this
+ * function and that illegal gamma values are auto-corrected and not
+ * reported as errors.
+ *
+ * Return: 0 on success, < 0 if error occurred.
+ */
+static int set_gamma(struct fbtft_par *par, unsigned long *curves)
+{
+	int i;
+	int j;
+	int c; /* curve index offset */
+
+	/*
+	 * Bitmasks for gamma curve command parameters.
+	 * The masks are the same for both positive and negative voltage
+	 * gamma curves.
+	 */
+	const u8 gamma_par_mask[] = {
+		0xFF, /* V63[3:0], V0[3:0]*/
+		0x3F, /* V1[5:0] */
+		0x3F, /* V2[5:0] */
+		0x1F, /* V4[4:0] */
+		0x1F, /* V6[4:0] */
+		0x3F, /* J0[1:0], V13[3:0] */
+		0x7F, /* V20[6:0] */
+		0x77, /* V36[2:0], V27[2:0] */
+		0x7F, /* V43[6:0] */
+		0x3F, /* J1[1:0], V50[3:0] */
+		0x1F, /* V57[4:0] */
+		0x1F, /* V59[4:0] */
+		0x3F, /* V61[5:0] */
+		0x3F, /* V62[5:0] */
+	};
+
+	for (i = 0; i < par->gamma.num_curves; i++) {
+		c = i * par->gamma.num_values;
+		for (j = 0; j < par->gamma.num_values; j++)
+			curves[c + j] &= gamma_par_mask[j];
+		write_reg(
+			par, PVGAMCTRL + i,
+			curves[c + 0], curves[c + 1], curves[c + 2],
+			curves[c + 3], curves[c + 4], curves[c + 5],
+			curves[c + 6], curves[c + 7], curves[c + 8],
+			curves[c + 9], curves[c + 10], curves[c + 11],
+			curves[c + 12], curves[c + 13]);
+	}
+	return 0;
+}
+
+/**
+ * blank() - blank the display
+ *
+ * @par: FBTFT parameter object
+ * @on: whether to enable or disable blanking the display
+ *
+ * Return: 0 on success, < 0 if error occurred.
+ */
+static int blank(struct fbtft_par *par, bool on)
+{
+	if (on)
+		write_reg(par, DISPOFF);
+	else
+		write_reg(par, DISPON);
+	return 0;
+}
+
+static struct fbtft_display display = {
+	.regwidth = 8,
+	.width = 240,
+	.height = 320,
+	.init_sequence = default_init_sequence,
+	.gamma_num = 2,
+	.gamma_len = 14,
+	.gamma = DEFAULT_GAMMA,
+	.fbtftops = {
+		.set_addr_win = set_addr_win,
+		.set_var = set_var,
+		.set_gamma = set_gamma,
+		.blank = blank,
+	},
+};
+
+FBTFT_REGISTER_DRIVER(DRVNAME, "sitronix,st7789v", &display);
+
+MODULE_ALIAS("spi:" DRVNAME);
+MODULE_ALIAS("platform:" DRVNAME);
+MODULE_ALIAS("spi:st7789v");
+MODULE_ALIAS("platform:st7789v");
+
+MODULE_DESCRIPTION("FB driver for the ST7789V LCD Controller");
+MODULE_AUTHOR("Dennis Menschel");
+MODULE_LICENSE("GPL");