staging: fbtft: add fb_tls8204 driver

This commit adds the fb_tls8204 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

@@ -133,3 +133,9 @@ config FB_TFT_TINYLCD
 	depends on FB_TFT
 	help
 	  Custom Framebuffer support for tinylcd.com display
+
+config FB_TFT_TLS8204
+	tristate "FB driver for the TLS8204 LCD Controller"
+	depends on FB_TFT
+	help
+	  Generic Framebuffer support for TLS8204

drivers/staging/fbtft/Makefile

@@ -24,3 +24,4 @@ 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_TINYLCD)     += fb_tinylcd.o
+obj-$(CONFIG_FB_TFT_TLS8204)     += fb_tls8204.o

drivers/staging/fbtft/fb_tls8204.c

+/*
+ * FB driver for the TLS8204 LCD Controller
+ *
+ * The display is monochrome and the video memory is RGB565.
+ * Any pixel value except 0 turns the pixel on.
+ *
+ * Copyright (C) 2013 Noralf Tronnes
+ * Copyright (C) 2014 Michael Hope (adapted for the TLS8204)
+ *
+ * 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/spi/spi.h>
+#include <linux/delay.h>
+
+#include "fbtft.h"
+
+#define DRVNAME		"fb_tls8204"
+#define WIDTH		84
+#define HEIGHT		48
+#define TXBUFLEN	WIDTH
+#define DEFAULT_GAMMA	"40" /* gamma is used to control contrast in this driver */
+
+static unsigned bs = 4;
+module_param(bs, uint, 0);
+MODULE_PARM_DESC(bs, "BS[2:0] Bias voltage level: 0-7 (default: 4)");
+
+static int init_display(struct fbtft_par *par)
+{
+	fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
+
+	par->fbtftops.reset(par);
+
+	/* Enter extended command mode */
+	write_reg(par, 0x21); /* 5:1  1
+				 2:0  PD - Powerdown control: chip is active
+				 1:0  V  - Entry mode: horizontal addressing
+				 0:1  H  - Extended instruction set control: extended
+			      */
+
+	/* H=1 Bias system */
+	write_reg(par, 0x10 | (bs & 0x7)); /*
+				 4:1  1
+				 3:0  0
+				 2:x  BS2 - Bias System
+				 1:x  BS1
+				 0:x  BS0
+			      */
+
+	/* Set the address of the first display line. */
+	write_reg(par, 0x04 | (64 >> 6));
+	write_reg(par, 0x40 | (64 & 0x3F));
+
+	/* Enter H=0 standard command mode */
+	write_reg(par, 0x20);
+
+	/* H=0 Display control */
+	write_reg(par, 0x08 | 4); /*
+				 3:1  1
+				 2:1  D  - DE: 10=normal mode
+				 1:0  0
+				 0:0  E
+			      */
+
+	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);
+
+	/* H=0 Set X address of RAM */
+	write_reg(par, 0x80); /* 7:1  1
+				 6-0: X[6:0] - 0x00
+			      */
+
+	/* H=0 Set Y address of RAM */
+	write_reg(par, 0x40); /* 7:0  0
+				 6:1  1
+				 2-0: Y[2:0] - 0x0
+			      */
+}
+
+static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
+{
+	u16 *vmem16 = (u16 *)par->info->screen_base;
+	int x, y, i;
+	int ret = 0;
+
+	fbtft_par_dbg(DEBUG_WRITE_VMEM, par, "%s()\n", __func__);
+
+	for (y = 0; y < HEIGHT/8; y++) {
+		u8 *buf = par->txbuf.buf;
+		/* The display is 102x68 but the LCD is 84x48.  Set
+		   the write pointer at the start of each row. */
+		gpio_set_value(par->gpio.dc, 0);
+		write_reg(par, 0x80 | 0);
+		write_reg(par, 0x40 | y);
+
+		for (x = 0; x < WIDTH; x++) {
+			u8 ch = 0;
+			for (i = 0; i < 8*WIDTH; i += WIDTH) {
+				ch >>= 1;
+				if (vmem16[(y*8*WIDTH)+i+x])
+					ch |= 0x80;
+			}
+			*buf++ = ch;
+		}
+		/* Write the row */
+		gpio_set_value(par->gpio.dc, 1);
+		ret = par->fbtftops.write(par, par->txbuf.buf, WIDTH);
+		if (ret < 0) {
+			dev_err(par->info->device,
+				"%s: write failed and returned: %d\n", __func__, ret);
+			break;
+		}
+	}
+
+	return ret;
+}
+
+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] &= 0x7F;
+
+	write_reg(par, 0x21); /* turn on extended instruction set */
+	write_reg(par, 0x80 | curves[0]);
+	write_reg(par, 0x20); /* turn off extended instruction set */
+
+	return 0;
+}
+
+
+static struct fbtft_display display = {
+	.regwidth = 8,
+	.width = WIDTH,
+	.height = HEIGHT,
+	.txbuflen = TXBUFLEN,
+	.gamma_num = 1,
+	.gamma_len = 1,
+	.gamma = DEFAULT_GAMMA,
+	.fbtftops = {
+		.init_display = init_display,
+		.set_addr_win = set_addr_win,
+		.write_vmem = write_vmem,
+		.set_gamma = set_gamma,
+	},
+	.backlight = 1,
+};
+FBTFT_REGISTER_DRIVER(DRVNAME, "teralane,tls8204", &display);
+
+MODULE_ALIAS("spi:" DRVNAME);
+MODULE_ALIAS("spi:tls8204");
+
+MODULE_DESCRIPTION("FB driver for the TLS8204 LCD Controller");
+MODULE_AUTHOR("Michael Hope");
+MODULE_LICENSE("GPL");