/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2008 Rafaël Carré
 *
 * 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 software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

.text

/* AS3525 hardware registers */
.set GPIOA,     0xC80B0000
.set GPIOB,     0xC80C0000
.set GPIOC,     0xC80D0000
.set GPIOD,     0xC80E0000
.set CGU_PERI,  0xC80F0014
.set I2C_BASE,  0xC8070000
.set I2C_DATA,  0x00
.set I2C_SLAD0, 0x04
.set I2C_CNTRL, 0x0c
.set I2C_DACNT, 0x10
.set I2C_CPSR0, 0x1c
.set I2C_CPSR1, 0x20
.set I2C_IMR,   0x24
.set I2C_SR,    0x30
.set I2C_SADDR, 0x44
.set AS3514_I2C_ADDR, 0x46
.set AS3514_IRQ_ENRD0, 0x25
.set PCLK, 24000000
.set I2C_CLK, 400000
.set I2C_PRESCALER, ((PCLK + I2C_CLK -1) / I2C_CLK)
.set I2C_PRESCALER_LOW, (I2C_PRESCALER & 0xff)
.set I2C_PRESCALER_HIGH, (I2C_PRESCALER >> 8)
#if I2C_PRESCALER_HIGH > 3
#error i2c prescaler too big!
#endif

/* Vectors */

        ldr   pc, =start    /* reset vector */
        /* next vectors are unused, halt cpu */
1:      b 1b
1:      b 1b
1:      b 1b
1:      b 1b
1:      b 1b
1:      b 1b
1:      b 1b


/* These values are filled in by mkamsboot - don't move them from offset 0x20 */

uclunpack_end:   .word   0 /* End of the ucl_unpack function */
uclunpack_size:  .word   0 /* Size in bytes of the ucl_unpack function */

ucl_of_end:      .word   0 /* End of the ucl-compressed OF image */
ucl_of_size:     .word   0 /* Size in bytes of the compressed OF image */

ucl_rb_end:      .word   0 /* End of the ucl-compressed RB image */
ucl_rb_size:     .word   0 /* Size in bytes of the compressed RB image */

ucl_dest:        .word   0 /* End of our destination buffer (end of memory) */

start:
        /* First copy the UCL unpack function to the end of RAM */
        ldr     r0, uclunpack_end   /* Source */
        ldr     r1, uclunpack_size  /* Source length */
        sub     r2, r0, r1          /* Source start - 1*/

        ldr     r3, ucl_dest        /* Destination end */

uclcopy:
        ldrb    r4, [r0], #-1
        strb    r4, [r3], #-1
        cmp     r2, r0
        bne     uclcopy

        /* store the new destination buffer */
        str     r3, ucl_dest

        /* enable gpio clock */
        ldr     r0, =CGU_PERI
        ldr     r1, [r0]
        orr     r1, r1, #(1<<16)
        str     r1, [r0]


/* TODO : M200V4 ? */
#if defined(SANSA_CLIP) || defined(SANSA_CLIPV2)
#define USB_PIN 6
#elif defined(SANSA_FUZE) || defined(SANSA_E200V2) || defined(SANSA_FUZEV2)
#define USB_PIN 3
#endif

#ifdef USB_PIN  /* TODO : remove this check when we'll have an USB driver */
        ldr     r0, =GPIOA
        mov     r1, #0
        str     r1, [r0, #0x400]
        ldr     r1, [r0, #(4*(1<<USB_PIN))]
        cmp     r1, #0
        bne     boot_of
#endif
#if defined(SANSA_C200V2)
        /* Instead of checking the GPIO, check the audio master IRQ_ENRD0
         * USB_STATUS bit on C200V2 */

        ldr     r0, =CGU_PERI
        ldr     r1, [r0]
        /* enable i2c audio master clock */
        orr     r1, r1, #(1<<17)
        /* make sure 24MHz clk_main is selected */
        bic     r1, r1, #0x7f
        str     r1, [r0]

        ldr     r0, =I2C_BASE
        /* disable i2c interrupts */
        mov     r1, #0
        str     r1, [r0, #I2C_IMR]
        /* setup prescaler */
        mov     r1, #I2C_PRESCALER_LOW
        str     r1, [r0, #I2C_CPSR0]
        mov     r1, #I2C_PRESCALER_HIGH
        str     r1, [r0, #I2C_CPSR1]
        /* setup i2c slave address */
        mov     r1, #(AS3514_I2C_ADDR << 1)
        str     r1, [r0, #I2C_SLAD0]
        mov     r2, #0x51
        str     r2, [r0, #I2C_CNTRL]

        /* wait for not busy */
1:
        ldr     r1, [r0, #I2C_SR]
        tst     r1, #1
        bne 1b

        /* start read of irq_enrd0 */
        mov     r1, #AS3514_IRQ_ENRD0
        str     r1, [r0, #I2C_SADDR]
        orr     r2, r2, #(1 << 1)
        str     r2, [r0, #I2C_CNTRL]
        mov     r1, #1
        str     r1, [r0, #I2C_DACNT]

        /* wait for transfer to finish */
1:
        ldr     r1, [r0, #I2C_DACNT]
        cmp     r1, #0
        bne     1b

        /* load result and test USB_STATUS bit */
        ldr     r1, [r0, #I2C_DATA]
        tst     r1, #(1 << 3)
        bne     boot_of
#endif

        /* Here are model specific tests, for dual boot without a computer */
        /* All models use left button */
        /* /!\ Right button for c200v2 (left button is unkwown) */

#ifdef SANSA_CLIP
.set row, (1<<5) /* enable output on C5 */
.set col, (1<<0) /* read keyscan column B0 */

        ldr     r0, =GPIOC
        mov     r1, #row
        str     r1, [r0, #0x400]
        str     r1, [r0, #(4*row)]

        ldr     r0, =GPIOB
        mov     r1, #0
        str     r1, [r0, #0x400]
        ldr     r1, [r0, #(4*col)]

        cmp     r1, #0
        bne     boot_of
#elif defined(SANSA_CLIPV2)
.set row, (1<<4) /* enable output on D4 */
.set col, (1<<0) /* read keyscan column D0 */

        ldr     r0, =GPIOD
        mov     r1, #((1<<5)|(1<<4)|(1<<3)) /* all rows as output */
        str     r1, [r0, #0x400]

        /* all rows high */
        mov     r1, #(1<<3)
        str     r1, [r0, #(4*(1<<3))]
        mov     r1, #(1<<4)
        str     r1, [r0, #(4*(1<<4))]
        mov     r1, #(1<<5)
        str     r1, [r0, #(4*(1<<5))]

        mov     r1, #0                      /* button row low */
        str     r1, [r0, #(4*row)]

        mov     r1, #5                      /* small delay */
1:      subs    r1, r1, #1
        bne     1b

        ldr     r1, [r0, #(4*col)]

        cmp     r1, #0
        beq     boot_of
#elif defined(SANSA_E200V2) || defined(SANSA_FUZE) || defined(SANSA_FUZEV2)
        ldr     r0, =GPIOC
        mov     r1, #0
        str     r1, [r0, #0x400]
        ldr     r1, [r0, #0x20]    /* read pin C3 */

        cmp     r1, #0             /* C3 = #0 means button pressed */
#ifdef SANSA_FUZEV2
        /* the logic is reversed on the fuzev2 */
        bne     boot_of
#else
        beq     boot_of
#endif /* SANSA_FUZEV2 */

#elif defined(SANSA_CLIPPLUS)
        @ read pins
        ldr     r0, =GPIOC
        ldr     r1, [r0, #4*(1<<3)] @ read pin C3 "|<<"

        ldr     r0, =GPIOA
        ldr     r2, [r0, #4*(1<<1)] @ read pin A1 "Home"

        orr     r2, r2, r1          @ c3 || A1

        cmp     r2, #0              @ test input from pins
        bne     boot_of             @ branch directly to OF if either pin high
#elif defined(SANSA_C200V2)
        /* check for RIGHT on C6, should changed to LEFT as soon as it
         * known in which pin that is in order for consistency  */
        ldr     r0, =GPIOC
        mov     r1, #0
        str     r1, [r0, #0x400]      /* set pin to output */

        ldr     r1, [r0, #256]        /* 1<<(6+2) */
        cmp     r1, #0                /* C6 low means button pressed */
        beq     boot_of
#elif defined(SANSA_M200V4)
.set row, (1<<5) /* enable output on A5 */
.set col, (1<<0) /* read keyscan column A0 */

        ldr     r0, =GPIOA
        mov     r1, #row
        str     r1, [r0, #0x400]
        str     r1, [r0, #(4*row)]

        ldr     r2, [r0, #(4*col)]

        /* check value read (1 means button pressed) */
        cmp     r2, #0
        bne     boot_of
#else
        #error No target-specific key check defined!
#endif


        /* The dualboot button was not held, so we boot rockbox */
        ldr     r0, ucl_rb_end      /* Address of compressed image */
        ldr     r1, ucl_rb_size     /* Compressed size */
        b       decompress

boot_of:
        ldr     r0, ucl_of_end      /* Address of compressed image */
        ldr     r1, ucl_of_size     /* Compressed size */


decompress:
        /* At this point:                                              */
        /* r0 = source_end for UCL image to copy                       */
        /* r1 = size of UCL image to copy                              */

        ldr     r3, ucl_dest
        add     r5, r3, #2      /* r5 is entry point of copy of uclunpack */
                                /* function, plus one (for thumb mode */

        sub     r4, r3, r1      /* r4 := destination_start - 1 */

fw_copy:
        ldrb    r2, [r0], #-1
        strb    r2, [r3], #-1
        cmp     r3, r4          /* Stop when we reached dest_start-1 */
        bne     fw_copy

        /* Call the ucl decompress function, which will branch to 0x0 */
        /* on completion */
        add     r0, r3, #1      /* r0 := Start of compressed image */
                                /* r1 already contains compressed size */
        mov     r2, #0          /* r2 := Destination for unpacking */
        bx      r5              /* Branch to uclunpack, switching to thumb */

        /* never reached : uclunpack will branch to the reset vector (0x0) */