/*************************************************************************** * __________ __ ___. * Open \______ \ ____ ____ | | _\_ |__ _______ ___ * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ * \/ \/ \/ \/ \/ * $Id$ * * Copyright (C) 2004 by Jens Arnold * Based on the work of Alan Korr and Jörg Hohensohn * * All files in this archive are subject to the GNU General Public License. * See the file COPYING in the source tree root for full license agreement. * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY * KIND, either express or implied. * ****************************************************************************/ #include "config.h" #include "sh7034.h" #define LCDR (PBDR_ADDR+1) #ifdef HAVE_LCD_CHARCELLS #define LCD_DS 1 /* PB0 = 1 --- 0001 --- LCD-DS */ #define LCD_CS 2 /* PB1 = 1 --- 0010 --- /LCD-CS */ #define LCD_SD 4 /* PB2 = 1 --- 0100 --- LCD-SD */ #define LCD_SC 8 /* PB3 = 1 --- 1000 --- LCD-SC */ #else #define LCD_SD 1 /* PB0 = 1 --- 0001 */ #define LCD_SC 2 /* PB1 = 1 --- 0010 */ #define LCD_RS 4 /* PB2 = 1 --- 0100 */ #define LCD_CS 8 /* PB3 = 1 --- 1000 */ #define LCD_DS LCD_RS #endif /* * About /CS,DS,SC,SD * ------------------ * * LCD on JBP and JBR uses a SPI protocol to receive orders (SDA and SCK lines) * * - /CS -> Chip Selection line : * 0 : LCD chipset is activated. * - DS -> Data Selection line, latched at the rising edge * of the 8th serial clock (*) : * 0 : instruction register, * 1 : data register; * - SC -> Serial Clock line (SDA). * - SD -> Serial Data line (SCK), latched at the rising edge * of each serial clock (*). * * _ _ * /CS \ / * \______________________________________________________/ * _____ ____ ____ ____ ____ ____ ____ ____ ____ _____ * SD \/ D7 \/ D6 \/ D5 \/ D4 \/ D3 \/ D2 \/ D1 \/ D0 \/ * _____/\____/\____/\____/\____/\____/\____/\____/\____/\_____ * * _____ _ _ _ _ _ _ _ ________ * SC \ * \ * \ * \ * \ * \ * \ * \ * * \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ * _ _________________________________________________________ * DS \/ * _/\_________________________________________________________ * */ .section .icode,"ax",@progbits .align 2 .global _lcd_write_command .type _lcd_write_command,@function /* Write a command byte to the lcd controller * * Arguments: * r4 - data byte (int) * * Register usage: * r0 - scratch * r1 - data byte (copied) * r2 - precalculated port value (CS, DS and SC low, SD high), * negated (neg)! * r3 - lcd port address * r5 - 1 (byte count for reuse of the loop in _lcd_write_data) */ _lcd_write_command: mov.l .lcdr,r3 /* put lcd data port address in r3 */ mov r4,r1 /* copy data byte to r1 */ mov #1,r5 /* set byte count to 1 (!) */ /* This code will fail if an interrupt changes the contents of PBDRL. * If so, we must disable the interrupt here. */ mov.b @r3,r0 /* r0 = PBDRL */ or #(LCD_SD),r0 /* r0 |= LCD_SD */ and #(~(LCD_CS|LCD_DS|LCD_SC)),r0 /* r0 &= ~(LCD_CS|LCD_DS|LCD_SC) */ bra .single_transfer /* jump into the transfer loop */ neg r0,r2 /* r2 = 0 - r0 */ .align 2 .global _lcd_write_data .type _lcd_write_data,@function /* A high performance function to write data to the display, * one or multiple bytes. * * Arguments: * r4 - data address * r5 - byte count * * Register usage: * r0 - scratch * r1 - current data byte * r2 - precalculated port value (CS and SC low, DS and SD high), * negated (neg)! * r3 - lcd port address */ _lcd_write_data: mov.l .lcdr,r3 /* put lcd data port address in r3 */ nop /* align here */ /* This code will fail if an interrupt changes the contents of PBDRL. * If so, we must disable the interrupt here. If disabling interrupts * for a long time (~9200 clks = ~830 µs for transferring 112 bytes on * recorders)is undesirable, the loop has to be rewritten to * disable/precalculate/transfer/enable for each iteration. However, * this would significantly decrease performance. */ mov.b @r3,r0 /* r0 = PBDRL */ or #(LCD_DS|LCD_SD),r0 /* r0 |= LCD_DS|LCD_SD */ and #(~(LCD_CS|LCD_SC)),r0 /* r0 &= ~(LCD_CS|LCD_SC) */ neg r0,r2 /* r2 = 0 - r0 */ #ifdef HAVE_LCD_CHARCELLS /* optimized player version, also works for recorders */ .align 2 .multi_transfer: mov.b @r4+,r1 /* load data byte from memory */ .single_transfer: shll16 r1 /* shift data to most significant byte */ shll8 r1 shll r1 /* shift the msb into carry */ neg r2,r0 /* copy negated precalculated port value */ /* uses neg here for compatibility with recorder version */ bt 1f /* data bit = 1? */ and #(~LCD_SD),r0 /* no: r0 &= ~LCD_SD */ 1: shll r1 /* next shift here for alignment */ mov.b r0,@r3 /* set data to port */ or #(LCD_SC),r0 /* rise SC (independent of SD level) */ mov.b r0,@r3 /* set to port */ neg r2,r0 bt 1f and #(~LCD_SD),r0 1: mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 shll r1 neg r2,r0 bt 1f and #(~LCD_SD),r0 1: shll r1 mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 neg r2,r0 bt 1f and #(~LCD_SD),r0 1: mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 shll r1 neg r2,r0 bt 1f and #(~LCD_SD),r0 1: shll r1 mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 neg r2,r0 bt 1f and #(~LCD_SD),r0 1: mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 shll r1 neg r2,r0 bt 1f and #(~LCD_SD),r0 1: shll r1 mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 neg r2,r0 bt 1f and #(~LCD_SD),r0 1: mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 #else /* HAVE_LCD_CHARCELLS */ /* further optimized version, exploits that SD is on bit 0 for recorders */ .align 2 .multi_transfer: mov.b @r4+,r1 /* load data byte from memory */ nop .single_transfer: shll16 r1 /* shift data to most significant byte */ shll8 r1 not r1,r1 /* and invert for use with negc */ shll r1 /* shift the MSB into carry */ negc r2,r0 /* carry to SD, SC low */ shll r1 /* next shift here for alignment */ mov.b r0,@r3 /* set data to port */ or #(LCD_SC),r0 /* rise SC (independent of SD level) */ mov.b r0,@r3 /* set to port */ negc r2,r0 mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 shll r1 negc r2,r0 shll r1 mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 negc r2,r0 mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 shll r1 negc r2,r0 shll r1 mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 negc r2,r0 mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 shll r1 negc r2,r0 shll r1 mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 negc r2,r0 mov.b r0,@r3 or #(LCD_SC),r0 mov.b r0,@r3 #endif /* HAVE_LCD_CHARCELLS */ add #-1,r5 /* decrease byte count */ tst r5,r5 /* r5 == 0 ? */ bf .multi_transfer /* no: next iteration */ or #(LCD_CS|LCD_DS|LCD_SD|LCD_SC),r0 /* restore port */ rts mov.b r0,@r3 /* This is the place to reenable the interrupts, if we have disabled * them. See above. */ .align 2 .lcdr: .long LCDR .end: .size _lcd_write_command,.end-_lcd_write_command