// SPDX-License-Identifier: GPL-2.0+
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/*
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* FB driver for the UltraChip UC1611 LCD controller
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*
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* The display is 4-bit grayscale (16 shades) 240x160.
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*
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* Copyright (C) 2015 Henri Chain
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/gpio/consumer.h>
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#include <linux/spi/spi.h>
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#include <linux/delay.h>
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#include "fbtft.h"
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#define DRVNAME "fb_uc1611"
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#define WIDTH 240
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#define HEIGHT 160
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#define BPP 8
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#define FPS 40
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/*
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* LCD voltage is a combination of ratio, gain, pot and temp
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*
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* V_LCD = V_BIAS * ratio
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* V_LCD = (C_V0 + C_PM × pot) * (1 + (T - 25) * temp)
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* C_V0 and C_PM depend on ratio and gain
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* T is ambient temperature
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*/
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/* BR -> actual ratio: 0-3 -> 5, 10, 11, 13 */
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static unsigned int ratio = 2;
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module_param(ratio, uint, 0000);
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MODULE_PARM_DESC(ratio, "BR[1:0] Bias voltage ratio: 0-3 (default: 2)");
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static unsigned int gain = 3;
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module_param(gain, uint, 0000);
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MODULE_PARM_DESC(gain, "GN[1:0] Bias voltage gain: 0-3 (default: 3)");
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static unsigned int pot = 16;
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module_param(pot, uint, 0000);
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MODULE_PARM_DESC(pot, "PM[6:0] Bias voltage pot.: 0-63 (default: 16)");
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/* TC -> % compensation per deg C: 0-3 -> -.05, -.10, -.015, -.20 */
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static unsigned int temp;
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module_param(temp, uint, 0000);
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MODULE_PARM_DESC(temp, "TC[1:0] Temperature compensation: 0-3 (default: 0)");
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/* PC[1:0] -> LCD capacitance: 0-3 -> <20nF, 20-28 nF, 29-40 nF, 40-56 nF */
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static unsigned int load = 1;
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module_param(load, uint, 0000);
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MODULE_PARM_DESC(load, "PC[1:0] Panel Loading: 0-3 (default: 1)");
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/* PC[3:2] -> V_LCD: 0, 1, 3 -> ext., int. with ratio = 5, int. standard */
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static unsigned int pump = 3;
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module_param(pump, uint, 0000);
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MODULE_PARM_DESC(pump, "PC[3:2] Pump control: 0,1,3 (default: 3)");
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static int init_display(struct fbtft_par *par)
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{
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int ret;
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/*
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* Set CS active inverse polarity: just setting SPI_CS_HIGH does not
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* work with GPIO based chip selects that are logically active high
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* but inverted inside the GPIO library, so enforce inverted
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* semantics.
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*/
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par->spi->mode ^= SPI_CS_HIGH;
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ret = spi_setup(par->spi);
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if (ret) {
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dev_err(par->info->device,
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"Could not set inverse CS polarity\n");
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return ret;
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}
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/* Reset controller */
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write_reg(par, 0xE2);
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/* Set bias ratio */
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write_reg(par, 0xE8 | (ratio & 0x03));
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/* Set bias gain and potentiometer */
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write_reg(par, 0x81);
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write_reg(par, (gain & 0x03) << 6 | (pot & 0x3F));
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/* Set temperature compensation */
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write_reg(par, 0x24 | (temp & 0x03));
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/* Set panel loading */
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write_reg(par, 0x28 | (load & 0x03));
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/* Set pump control */
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write_reg(par, 0x2C | (pump & 0x03));
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/* Set inverse display */
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write_reg(par, 0xA6 | 0x01);
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/* Set 4-bit grayscale mode */
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write_reg(par, 0xD0 | (0x02 & 0x03));
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/* Set Display enable */
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write_reg(par, 0xA8 | 0x07);
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return 0;
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}
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static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
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{
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switch (par->info->var.rotate) {
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case 90:
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case 270:
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/* Set column address */
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write_reg(par, ys & 0x0F);
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write_reg(par, 0x10 | (ys >> 4));
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/* Set page address (divide xs by 2) (not used by driver) */
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write_reg(par, 0x60 | ((xs >> 1) & 0x0F));
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write_reg(par, 0x70 | (xs >> 5));
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break;
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default:
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/* Set column address (not used by driver) */
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write_reg(par, xs & 0x0F);
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write_reg(par, 0x10 | (xs >> 4));
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/* Set page address (divide ys by 2) */
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write_reg(par, 0x60 | ((ys >> 1) & 0x0F));
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write_reg(par, 0x70 | (ys >> 5));
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break;
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}
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}
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static int blank(struct fbtft_par *par, bool on)
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{
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fbtft_par_dbg(DEBUG_BLANK, par, "(%s=%s)\n",
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__func__, on ? "true" : "false");
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if (on)
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write_reg(par, 0xA8 | 0x00);
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else
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write_reg(par, 0xA8 | 0x07);
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return 0;
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}
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static int set_var(struct fbtft_par *par)
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{
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/* par->info->fix.visual = FB_VISUAL_PSEUDOCOLOR; */
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par->info->var.grayscale = 1;
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par->info->var.red.offset = 0;
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par->info->var.red.length = 8;
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par->info->var.green.offset = 0;
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par->info->var.green.length = 8;
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par->info->var.blue.offset = 0;
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par->info->var.blue.length = 8;
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par->info->var.transp.offset = 0;
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par->info->var.transp.length = 0;
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switch (par->info->var.rotate) {
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case 90:
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/* Set RAM address control */
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write_reg(par, 0x88
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| (0x0 & 0x1) << 2 /* Increment positively */
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| (0x1 << 1) /* Increment page first */
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| 0x1); /* Wrap around (default) */
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/* Set LCD mapping */
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write_reg(par, 0xC0
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| (0x0 & 0x1) << 2 /* Mirror Y OFF */
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| (0x0 & 0x1) << 1 /* Mirror X OFF */
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| (0x0 & 0x1)); /* MS nibble last (default) */
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break;
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case 180:
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/* Set RAM address control */
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write_reg(par, 0x88
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| (0x0 & 0x1) << 2 /* Increment positively */
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| (0x0 & 0x1) << 1 /* Increment column first */
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| 0x1); /* Wrap around (default) */
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/* Set LCD mapping */
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write_reg(par, 0xC0
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| (0x1 << 2) /* Mirror Y ON */
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| (0x0 & 0x1) << 1 /* Mirror X OFF */
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| (0x0 & 0x1)); /* MS nibble last (default) */
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break;
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case 270:
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/* Set RAM address control */
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write_reg(par, 0x88
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| (0x0 & 0x1) << 2 /* Increment positively */
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| (0x1 << 1) /* Increment page first */
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| 0x1); /* Wrap around (default) */
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/* Set LCD mapping */
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write_reg(par, 0xC0
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| (0x1 << 2) /* Mirror Y ON */
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| (0x1 << 1) /* Mirror X ON */
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| (0x0 & 0x1)); /* MS nibble last (default) */
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break;
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default:
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/* Set RAM address control */
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write_reg(par, 0x88
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| (0x0 & 0x1) << 2 /* Increment positively */
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| (0x0 & 0x1) << 1 /* Increment column first */
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| 0x1); /* Wrap around (default) */
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/* Set LCD mapping */
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write_reg(par, 0xC0
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| (0x0 & 0x1) << 2 /* Mirror Y OFF */
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| (0x1 << 1) /* Mirror X ON */
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| (0x0 & 0x1)); /* MS nibble last (default) */
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break;
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}
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return 0;
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}
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static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
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{
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u8 *vmem8 = (u8 *)(par->info->screen_buffer);
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u8 *buf8 = par->txbuf.buf;
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u16 *buf16 = par->txbuf.buf;
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int line_length = par->info->fix.line_length;
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int y_start = offset / line_length;
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int y_end = (offset + len - 1) / line_length;
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int x, y, i;
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int ret = 0;
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switch (par->pdata->display.buswidth) {
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case 8:
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switch (par->info->var.rotate) {
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case 90:
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case 270:
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i = y_start * line_length;
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for (y = y_start; y <= y_end; y++) {
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for (x = 0; x < line_length; x += 2) {
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*buf8 = vmem8[i] >> 4;
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*buf8 |= vmem8[i + 1] & 0xF0;
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buf8++;
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i += 2;
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}
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}
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break;
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default:
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/* Must be even because pages are two lines */
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y_start &= 0xFE;
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i = y_start * line_length;
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for (y = y_start; y <= y_end; y += 2) {
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for (x = 0; x < line_length; x++) {
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*buf8 = vmem8[i] >> 4;
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*buf8 |= vmem8[i + line_length] & 0xF0;
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buf8++;
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i++;
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}
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i += line_length;
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}
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break;
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}
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gpiod_set_value(par->gpio.dc, 1);
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/* Write data */
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ret = par->fbtftops.write(par, par->txbuf.buf, len / 2);
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break;
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case 9:
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switch (par->info->var.rotate) {
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case 90:
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case 270:
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i = y_start * line_length;
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for (y = y_start; y <= y_end; y++) {
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for (x = 0; x < line_length; x += 2) {
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*buf16 = 0x100;
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*buf16 |= vmem8[i] >> 4;
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*buf16 |= vmem8[i + 1] & 0xF0;
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buf16++;
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i += 2;
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}
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}
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break;
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default:
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/* Must be even because pages are two lines */
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y_start &= 0xFE;
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i = y_start * line_length;
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for (y = y_start; y <= y_end; y += 2) {
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for (x = 0; x < line_length; x++) {
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*buf16 = 0x100;
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*buf16 |= vmem8[i] >> 4;
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*buf16 |= vmem8[i + line_length] & 0xF0;
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buf16++;
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i++;
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}
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i += line_length;
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}
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break;
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}
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/* Write data */
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ret = par->fbtftops.write(par, par->txbuf.buf, len);
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break;
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default:
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dev_err(par->info->device, "unsupported buswidth %d\n",
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par->pdata->display.buswidth);
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}
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if (ret < 0)
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dev_err(par->info->device, "write failed and returned: %d\n",
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ret);
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return ret;
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}
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static struct fbtft_display display = {
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.txbuflen = -1,
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.regwidth = 8,
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.width = WIDTH,
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.height = HEIGHT,
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.bpp = BPP,
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.fps = FPS,
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.fbtftops = {
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.write_vmem = write_vmem,
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.init_display = init_display,
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.set_addr_win = set_addr_win,
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.set_var = set_var,
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.blank = blank,
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},
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};
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FBTFT_REGISTER_DRIVER(DRVNAME, "ultrachip,uc1611", &display);
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MODULE_ALIAS("spi:" DRVNAME);
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MODULE_ALIAS("platform:" DRVNAME);
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MODULE_ALIAS("spi:uc1611");
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MODULE_ALIAS("platform:uc1611");
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MODULE_DESCRIPTION("FB driver for the UC1611 LCD controller");
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MODULE_AUTHOR("Henri Chain");
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MODULE_LICENSE("GPL");
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