Staging: fbtft: Add support for the Ultrachip UC1611 LCD controller

This is a driver chip for 240x160 4-bit greyscale LCDs.
It is capable of 4-wire (8 bit) or 3-wire (9 bit) SPI that have both been
tested. (It also has a 6800 or 8080-style parallel interface, but I have
not included support for it.)

Signed-off-by: Henri Chain <henri.chain@eleves.ec-nantes.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 350 insertions, 0 deletions

diff --git a/drivers/staging/fbtft/fb_uc1611.c b/drivers/staging/fbtft/fb_uc1611.c
new file mode 100644
index 000000000000..32f3a9d921d6
--- /dev/null
+++ b/drivers/staging/fbtft/fb_uc1611.c
@@ -0,0 +1,350 @@
+/*
+ * FB driver for the UltraChip UC1611 LCD controller
+ *
+ * The display is 4-bit grayscale (16 shades) 240x160.
+ *
+ * Copyright (C) 2015 Henri Chain
+ *
+ * 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/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_uc1611"
+#define WIDTH		240
+#define HEIGHT		160
+#define BPP		8
+#define FPS		40
+
+/*
+ * LCD voltage is a combination of ratio, gain, pot and temp
+ *
+ * V_LCD = V_BIAS * ratio
+ * V_LCD = (C_V0 + C_PM × pot) * (1 + (T - 25) * temp)
+ * C_V0 and C_PM depend on ratio and gain
+ * T is ambient temperature
+ */
+
+/* BR -> actual ratio: 0-3 -> 5, 10, 11, 13 */
+static unsigned ratio = 2;
+module_param(ratio, uint, 0);
+MODULE_PARM_DESC(ratio, "BR[1:0] Bias voltage ratio: 0-3 (default: 2)");
+
+static unsigned gain = 3;
+module_param(gain, uint, 0);
+MODULE_PARM_DESC(gain, "GN[1:0] Bias voltage gain: 0-3 (default: 3)");
+
+static unsigned pot = 16;
+module_param(pot, uint, 0);
+MODULE_PARM_DESC(pot, "PM[6:0] Bias voltage pot.: 0-63 (default: 16)");
+
+/* TC -> % compensation per deg C: 0-3 -> -.05, -.10, -.015, -.20 */
+static unsigned temp;
+module_param(temp, uint, 0);
+MODULE_PARM_DESC(temp, "TC[1:0] Temperature compensation: 0-3 (default: 0)");
+
+/* PC[1:0] -> LCD capacitance: 0-3 -> <20nF, 20-28 nF, 29-40 nF, 40-56 nF */
+static unsigned load = 1;
+module_param(load, uint, 0);
+MODULE_PARM_DESC(load, "PC[1:0] Panel Loading: 0-3 (default: 1)");
+
+/* PC[3:2] -> V_LCD: 0, 1, 3 -> ext., int. with ratio = 5, int. standard */
+static unsigned pump = 3;
+module_param(pump, uint, 0);
+MODULE_PARM_DESC(pump, "PC[3:2] Pump control: 0,1,3 (default: 3)");
+
+static int init_display(struct fbtft_par *par)
+{
+	int ret;
+
+	fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
+
+	/* Set CS active high */
+	par->spi->mode |= SPI_CS_HIGH;
+	ret = par->spi->master->setup(par->spi);
+	if (ret) {
+		dev_err(par->info->device, "Could not set SPI_CS_HIGH\n");
+		return ret;
+	}
+
+	/* Reset controller */
+	write_reg(par, 0xE2);
+
+	/* Set bias ratio */
+	write_reg(par, 0xE8 | (ratio & 0x03));
+
+	/* Set bias gain and potentiometer */
+	write_reg(par, 0x81);
+	write_reg(par, (gain & 0x03) << 6 | (pot & 0x3F));
+
+	/* Set temperature compensation */
+	write_reg(par, 0x24 | (temp & 0x03));
+
+	/* Set panel loading */
+	write_reg(par, 0x28 | (load & 0x03));
+
+	/* Set pump control */
+	write_reg(par, 0x2C | (pump & 0x03));
+
+	/* Set inverse display */
+	write_reg(par, 0xA6 | (0x01 & 0x01));
+
+	/* Set 4-bit grayscale mode */
+	write_reg(par, 0xD0 | (0x02 & 0x03));
+
+	/* Set Display enable */
+	write_reg(par, 0xA8 | 0x07);
+
+	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);
+
+	switch (par->info->var.rotate) {
+	case 90:
+	case 270:
+		/* Set column address */
+		write_reg(par, ys & 0x0F);
+		write_reg(par, 0x10 | (ys >> 4));
+
+		/* Set page address (divide xs by 2) (not used by driver) */
+		write_reg(par, 0x60 | ((xs >> 1) & 0x0F));
+		write_reg(par, 0x70 | (xs >> 5));
+		break;
+	default:
+		/* Set column address (not used by driver) */
+		write_reg(par, xs & 0x0F);
+		write_reg(par, 0x10 | (xs >> 4));
+
+		/* Set page address (divide ys by 2) */
+		write_reg(par, 0x60 | ((ys >> 1) & 0x0F));
+		write_reg(par, 0x70 | (ys >> 5));
+		break;
+	}
+}
+
+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, 0xA8 | 0x00);
+	else
+		write_reg(par, 0xA8 | 0x07);
+	return 0;
+}
+
+static int set_var(struct fbtft_par *par)
+{
+	fbtft_par_dbg(DEBUG_INIT_DISPLAY, par, "%s()\n", __func__);
+
+	/* par->info->fix.visual = FB_VISUAL_PSEUDOCOLOR; */
+	par->info->var.grayscale = 1;
+	par->info->var.red.offset    = 0;
+	par->info->var.red.length    = 8;
+	par->info->var.green.offset  = 0;
+	par->info->var.green.length  = 8;
+	par->info->var.blue.offset   = 0;
+	par->info->var.blue.length   = 8;
+	par->info->var.transp.offset = 0;
+	par->info->var.transp.length = 0;
+
+	switch (par->info->var.rotate) {
+	case 90:
+		/* Set RAM address control */
+		write_reg(par, 0x88
+			| (0x0 & 0x1) << 2 /* Increment positively */
+			| (0x1 & 0x1) << 1 /* Increment page first */
+			| (0x1 & 0x1));    /* Wrap around (default) */
+
+		/* Set LCD mapping */
+		write_reg(par, 0xC0
+			| (0x0 & 0x1) << 2 /* Mirror Y OFF */
+			| (0x0 & 0x1) << 1 /* Mirror X OFF */
+			| (0x0 & 0x1));    /* MS nibble last (default) */
+		break;
+	case 180:
+		/* Set RAM address control */
+		write_reg(par, 0x88
+			| (0x0 & 0x1) << 2 /* Increment positively */
+			| (0x0 & 0x1) << 1 /* Increment column first */
+			| (0x1 & 0x1));    /* Wrap around (default) */
+
+		/* Set LCD mapping */
+		write_reg(par, 0xC0
+			| (0x1 & 0x1) << 2 /* Mirror Y ON */
+			| (0x0 & 0x1) << 1 /* Mirror X OFF */
+			| (0x0 & 0x1));    /* MS nibble last (default) */
+		break;
+	case 270:
+		/* Set RAM address control */
+		write_reg(par, 0x88
+			| (0x0 & 0x1) << 2 /* Increment positively */
+			| (0x1 & 0x1) << 1 /* Increment page first */
+			| (0x1 & 0x1));    /* Wrap around (default) */
+
+		/* Set LCD mapping */
+		write_reg(par, 0xC0
+			| (0x1 & 0x1) << 2 /* Mirror Y ON */
+			| (0x1 & 0x1) << 1 /* Mirror X ON */
+			| (0x0 & 0x1));    /* MS nibble last (default) */
+		break;
+	default:
+		/* Set RAM address control */
+		write_reg(par, 0x88
+			| (0x0 & 0x1) << 2 /* Increment positively */
+			| (0x0 & 0x1) << 1 /* Increment column first */
+			| (0x1 & 0x1));    /* Wrap around (default) */
+
+		/* Set LCD mapping */
+		write_reg(par, 0xC0
+			| (0x0 & 0x1) << 2 /* Mirror Y OFF */
+			| (0x1 & 0x1) << 1 /* Mirror X ON */
+			| (0x0 & 0x1));    /* MS nibble last (default) */
+		break;
+	}
+
+	return 0;
+}
+
+static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
+{
+	u8 *vmem8 = (u8 *)(par->info->screen_base);
+	u8 *buf8 = (u8 *)(par->txbuf.buf);
+	u16 *buf16 = (u16 *)(par->txbuf.buf);
+	int line_length = par->info->fix.line_length;
+	int y_start = (offset / line_length);
+	int y_end = (offset + len - 1) / line_length;
+	int x, y, i;
+	int ret = 0;
+
+	fbtft_par_dbg(DEBUG_WRITE_VMEM, par, "%s()\n", __func__);
+
+	switch (par->pdata->display.buswidth) {
+	case 8:
+		switch (par->info->var.rotate) {
+		case 90:
+		case 270:
+			i = y_start * line_length;
+			for (y = y_start; y <= y_end; y++) {
+				for (x = 0; x < line_length; x += 2) {
+					*buf8 = vmem8[i] >> 4;
+					*buf8 |= vmem8[i + 1] & 0xF0;
+					buf8++;
+					i += 2;
+				}
+			}
+			break;
+		default:
+			/* Must be even because pages are two lines */
+			y_start &= 0xFE;
+			i = y_start * line_length;
+			for (y = y_start; y <= y_end; y += 2) {
+				for (x = 0; x < line_length; x++) {
+					*buf8 = vmem8[i] >> 4;
+					*buf8 |= vmem8[i + line_length] & 0xF0;
+					buf8++;
+					i++;
+				}
+				i += line_length;
+			}
+			break;
+		}
+		gpio_set_value(par->gpio.dc, 1);
+
+		/* Write data */
+		ret = par->fbtftops.write(par, par->txbuf.buf, len / 2);
+		break;
+	case 9:
+		switch (par->info->var.rotate) {
+		case 90:
+		case 270:
+			i = y_start * line_length;
+			for (y = y_start; y <= y_end; y++) {
+				for (x = 0; x < line_length; x += 2) {
+					*buf16 = 0x100;
+					*buf16 |= vmem8[i] >> 4;
+					*buf16 |= vmem8[i + 1] & 0xF0;
+					buf16++;
+					i += 2;
+				}
+			}
+			break;
+		default:
+			/* Must be even because pages are two lines */
+			y_start &= 0xFE;
+			i = y_start * line_length;
+			for (y = y_start; y <= y_end; y += 2) {
+				for (x = 0; x < line_length; x++) {
+					*buf16 = 0x100;
+					*buf16 |= vmem8[i] >> 4;
+					*buf16 |= vmem8[i + line_length] & 0xF0;
+					buf16++;
+					i++;
+				}
+				i += line_length;
+			}
+			break;
+		}
+
+		/* Write data */
+		ret = par->fbtftops.write(par, par->txbuf.buf, len);
+		break;
+	default:
+		dev_err(par->info->device, "unsupported buswidth %d\n",
+			par->pdata->display.buswidth);
+	}
+
+	if (ret < 0)
+		dev_err(par->info->device, "write failed and returned: %d\n",
+			ret);
+
+	return ret;
+}
+
+static struct fbtft_display display = {
+	.txbuflen = -1,
+	.regwidth = 8,
+	.width = WIDTH,
+	.height = HEIGHT,
+	.bpp = BPP,
+	.fps = FPS,
+	.fbtftops = {
+		.write_vmem = write_vmem,
+		.init_display = init_display,
+		.set_addr_win = set_addr_win,
+		.set_var = set_var,
+		.blank = blank,
+	},
+};
+
+FBTFT_REGISTER_DRIVER(DRVNAME, "ultrachip,uc1611", &display);
+
+MODULE_ALIAS("spi:" DRVNAME);
+MODULE_ALIAS("platform:" DRVNAME);
+MODULE_ALIAS("spi:uc1611");
+MODULE_ALIAS("platform:uc1611");
+
+MODULE_DESCRIPTION("FB driver for the UC1611 LCD controller");
+MODULE_AUTHOR("Henri Chain");
+MODULE_LICENSE("GPL");