cregit-Linux how code gets into the kernel

Release 4.14 arch/xtensa/platforms/xtfpga/lcd.c

/*
 * Driver for the LCD display on the Tensilica XTFPGA board family.
 * http://www.mytechcorp.com/cfdata/productFile/File1/MOC-16216B-B-A0A04.pdf
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2001, 2006 Tensilica Inc.
 * Copyright (C) 2015 Cadence Design Systems Inc.
 */

#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>

#include <platform/hardware.h>
#include <platform/lcd.h>

/* LCD instruction and data addresses. */

#define LCD_INSTR_ADDR		((char *)IOADDR(CONFIG_XTFPGA_LCD_BASE_ADDR))

#define LCD_DATA_ADDR		(LCD_INSTR_ADDR + 4)


#define LCD_CLEAR		0x1

#define LCD_DISPLAY_ON		0xc

/* 8bit and 2 lines display */

#define LCD_DISPLAY_MODE8BIT	0x38

#define LCD_DISPLAY_MODE4BIT	0x28

#define LCD_DISPLAY_POS		0x80

#define LCD_SHIFT_LEFT		0x18

#define LCD_SHIFT_RIGHT		0x1c


static void lcd_put_byte(u8 *addr, u8 data) { #ifdef CONFIG_XTFPGA_LCD_8BIT_ACCESS ACCESS_ONCE(*addr) = data; #else ACCESS_ONCE(*addr) = data & 0xf0; ACCESS_ONCE(*addr) = (data << 4) & 0xf0; #endif }

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static int __init lcd_init(void) { ACCESS_ONCE(*LCD_INSTR_ADDR) = LCD_DISPLAY_MODE8BIT; mdelay(5); ACCESS_ONCE(*LCD_INSTR_ADDR) = LCD_DISPLAY_MODE8BIT; udelay(200); ACCESS_ONCE(*LCD_INSTR_ADDR) = LCD_DISPLAY_MODE8BIT; udelay(50); #ifndef CONFIG_XTFPGA_LCD_8BIT_ACCESS ACCESS_ONCE(*LCD_INSTR_ADDR) = LCD_DISPLAY_MODE4BIT; udelay(50); lcd_put_byte(LCD_INSTR_ADDR, LCD_DISPLAY_MODE4BIT); udelay(50); #endif lcd_put_byte(LCD_INSTR_ADDR, LCD_DISPLAY_ON); udelay(50); lcd_put_byte(LCD_INSTR_ADDR, LCD_CLEAR); mdelay(10); lcd_disp_at_pos("XTENSA LINUX", 0); return 0; }

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void lcd_disp_at_pos(char *str, unsigned char pos) { lcd_put_byte(LCD_INSTR_ADDR, LCD_DISPLAY_POS | pos); udelay(100); while (*str != 0) { lcd_put_byte(LCD_DATA_ADDR, *str); udelay(200); str++; } }

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void lcd_shiftleft(void) { lcd_put_byte(LCD_INSTR_ADDR, LCD_SHIFT_LEFT); udelay(50); }

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void lcd_shiftright(void) { lcd_put_byte(LCD_INSTR_ADDR, LCD_SHIFT_RIGHT); udelay(50); }

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arch_initcall(lcd_init);

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