rockbox/firmware/drivers/lcd.S

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2004 by Jens Arnold
 * Based on the work of Alan Korr and J<EFBFBD>rg 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 "cpu.h"

#if CONFIG_CPU == SH7034
#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 <EFBFBD>s 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
#elif defined(IRIVER_H100_SERIES)
    .section    .icode,"ax",@progbits

    .align      2
    .global     lcd_write_command
    .type       lcd_write_command,@function

lcd_write_command:
    move.l  (4,%sp),%d0
    lea MBAR2,%a1
    move.l   #~8,%d1
    and.l   %d1,(0xb4,%a1)
    move.w  %d0,0xf0000000
    rts

    .align      2
    .global     lcd_write_command_ex
    .type       lcd_write_command_ex,@function

lcd_write_command_ex:
    lea MBAR2,%a1

    move.l  (4,%sp),%d0     /* Command */

    move.l   #~8,%d1        /* Set A0 = 0 */
    and.l   %d1,(0xb4,%a1)
    move.w  %d0,0xf0000000  /* Write to LCD */

    not.l   %d1             /* Set A0 = 1 */
    or.l    %d1,(0xb4,%a1)

    move.l  (8,%sp),%d0     /* Data */
    cmp.l   #0xffffffff,%d0 /* -1? */
    beq.b   .last
    move.w  %d0,0xf0000000  /* Write to LCD */

    move.l  (12,%sp),%d0    /* Data */
    cmp.l   #0xffffffff,%d0 /* -1? */
    beq.b   .last
    move.w  %d0,0xf0000000  /* Write to LCD */

.last:
    rts

    .align      2
    .global     lcd_write_data
    .type       lcd_write_data,@function

lcd_write_data:
    move.l  (4,%sp),%a0     /* Data pointer */
    move.l  (8,%sp),%d0     /* Length */
    lea MBAR2,%a1
    moveq   #8,%d1
    or.l    %d1,(0xb4,%a1)

    lea     0xf0000000,%a1
.loop:
    /* When running in IRAM, this loop takes 7 cycles plus the LCD write.
       The 7 cycles are necessary to follow the LCD timing specs
       at 140MHz */
    move.b  (%a0)+,%d1      /* 3(1/0) */
    move.w  %d1,(%a1)       /* 1(0/1) */
    subq.l  #1,%d0          /* 1(0/0) */
    nop                     /* 1(0/0) */
    bne     .loop           /* 2(0/0) */
    rts
#elif defined(IRIVER_H300_SERIES)
    .section    .icode,"ax",@progbits

    .align      2
    .global     lcd_write_data
    .type       lcd_write_data,@function

lcd_write_data:
    move.l  (4,%sp),%a0     /* data pointer */
    move.l  (8,%sp),%d0     /* length in words */
    add.l   %d0,%d0         /* words -> bytes */
    add.l   %a0,%d0         /* -> end address */
    lea.l   0xf0000002,%a1  /* LCD data port */
    
    move.l  %a0,%d1
    btst.l  #1,%d1          /* already longword aligned? */
    beq.b   .word1_end      /* yes: skip initial word copy */
    
    move.w  (%a0)+,(%a1)    /* transfer initial word */

.word1_end:                 /* now longword aligned */
    moveq.l #28,%d1
    add.l   %a0,%d1
    and.l   #0xFFFFFFF0,%d1 /* %d1 = first line bound + 16 */
    cmp.l   %d1,%d0         /* at least one full line to send? */
    blo.b   .long2_start    /* no: skip to trailing longword handling */

    lea.l   (-16,%sp),%sp   /* free up some registers */
    movem.l %d2-%d4/%a2,(%sp)

    subq.l  #8,%d1
    subq.l  #8,%d1          /* %d1 = first line bound */

    cmp.l   %a0,%d1         /* any leading longwords? */
    bls.b   .long1_end      /* no: skip leading long loop */
    
.long1_loop:
    move.l  (%a0)+,%d2      /* read longword */
    swap    %d2             /* send data to LCD in correct order...*/
    move.w  %d2,(%a1)
    swap    %d2
    move.w  %d2,(%a1)
    cmp.l   %a0,%d1         /* run %a0 up to first line bound */
    bhi.b   .long1_loop
    
.long1_end:
    move.l  %d0,%a2
    lea.l   (-14,%a2),%a2   /* %a2 = end address - 14 (one line/pass) */

    /* burst-optimised line transfers */
.line_loop:
    movem.l (%a0),%d1-%d4   /* burst-read line */
    lea.l   (16,%a0),%a0    /* increment address */
    swap    %d1             /* send data to LCD in correct order... */
    move.w  %d1,(%a1)
    swap    %d1
    move.w  %d1,(%a1)
    swap    %d2
    move.w  %d2,(%a1)
    swap    %d2
    move.w  %d2,(%a1)
    swap    %d3
    move.w  %d3,(%a1)
    swap    %d3
    move.w  %d3,(%a1)
    swap    %d4
    move.w  %d4,(%a1)
    swap    %d4
    move.w  %d4,(%a1)
    cmp.l   %a0,%a2         /* run %a0 up to last line bound */
    bhi.b   .line_loop
    
    movem.l (%sp),%d2-%d4/%a2
    lea.l   (16,%sp),%sp    /* restore registers */

.long2_start:
    subq.l  #2,%d0          /* account for handling 2 words per loop */
    cmp.l   %a0,%d0         /* any (trailing longwords? */
    bls.b   .long2_end      /* no: skip trailing longword loop */

.long2_loop:
    move.l  (%a0)+,%d1      /* read longword */
    swap    %d1             /* send data to LCD in correct order */
    move.w  %d1,(%a1)
    swap    %d1
    move.w  %d1,(%a1)
    cmp.l   %a0,%d0         /* run %a0 up to last long bound */
    bhi.b   .long2_loop
    
.long2_end:
    blo.b   .word2_end      /* no final word: skip */
    move.w  (%a0)+,(%a1)    /* transfer final word */

.word2_end:
    rts
#endif