staging: fbtft: add fb_pcd8544 driver

This commit adds the fb_pcd8544 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

@@ -73,3 +73,9 @@ config FB_TFT_ILI9486
 	depends on FB_TFT
 	help
 	  Generic Framebuffer support for ILI9486
+
+config FB_TFT_PCD8544
+	tristate "FB driver for the PCD8544 LCD Controller"
+	depends on FB_TFT
+	help
+	  Generic Framebuffer support for PCD8544

drivers/staging/fbtft/Makefile

@@ -14,3 +14,4 @@ obj-$(CONFIG_FB_TFT_ILI9340)     += fb_ili9340.o
 obj-$(CONFIG_FB_TFT_ILI9341)     += fb_ili9341.o
 obj-$(CONFIG_FB_TFT_ILI9481)     += fb_ili9481.o
 obj-$(CONFIG_FB_TFT_ILI9486)     += fb_ili9486.o
+obj-$(CONFIG_FB_TFT_PCD8544)     += fb_pcd8544.o

drivers/staging/fbtft/fb_pcd8544.c

+/*
+ * FB driver for the PCD8544 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
+ *
+ * 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_pcd8544"
+#define WIDTH          84
+#define HEIGHT         48
+#define TXBUFLEN       84*6
+#define DEFAULT_GAMMA  "40" /* gamma is used to control contrast in this driver */
+
+static unsigned tc = 0;
+module_param(tc, uint, 0);
+MODULE_PARM_DESC(tc, "TC[1:0] Temperature coefficient: 0-3 (default: 0)");
+
+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);
+
+	/* Function set */
+	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 Temperature control */
+	write_reg(par, 0x04 | (tc & 0x3)); /* 
+	                         2:1  1
+	                         1:x  TC1 - Temperature Coefficient: 0x10
+							 0:x  TC0
+						  */
+
+	/* 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
+	                      */
+
+	/* Function set */
+	write_reg(par, 0x22); /* 5:1  1
+	                         2:0  PD - Powerdown control: chip is active
+							 1:1  V  - Entry mode: vertical addressing
+							 0:0  H  - Extended instruction set control: basic
+						  */
+
+	/* 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;
+	u8 *buf = par->txbuf.buf;
+	int x, y, i;
+	int ret = 0;
+
+	fbtft_par_dbg(DEBUG_WRITE_VMEM, par, "%s()\n", __func__);
+
+	for (x=0;x<84;x++) {
+		for (y=0;y<6;y++) {
+			*buf = 0x00;
+			for (i=0;i<8;i++) {
+				*buf |= (vmem16[(y*8+i)*84+x] ? 1 : 0) << i;
+			}
+			buf++;
+		}
+	}
+
+	/* Write data */
+	gpio_set_value(par->gpio.dc, 1);
+	ret = par->fbtftops.write(par, par->txbuf.buf, 6*84);
+	if (ret < 0)
+		dev_err(par->info->device, "%s: write failed and returned: %d\n", __func__, ret);
+
+	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, 0x23); /* turn on extended instruction set */
+	write_reg(par, 0x80 | curves[0]);
+	write_reg(par, 0x22); /* 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, "philips,pdc8544", &display);
+
+MODULE_ALIAS("spi:" DRVNAME);
+MODULE_ALIAS("spi:pdc8544");
+
+MODULE_DESCRIPTION("FB driver for the PCD8544 LCD Controller");
+MODULE_AUTHOR("Noralf Tronnes");
+MODULE_LICENSE("GPL");