init.s

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#include <defBF531.h>
#include "config.h"


	.section/DOUBLEANY program;
	.align 2;
_InitSDRAM:
	[--SP] = ASTAT;
	[--SP] = RETS;
	[--SP] = (R7:0);
	[--SP] = (P5:0);


	/*
     * PLL_LOCKCNT - how many SCLK Cycles to delay while PLL becomes stable
     */
	p0.h = hi(PLL_LOCKCNT);
	p0.l = lo(PLL_LOCKCNT);
	r0 = 0x300(Z);
	w[p0] = r0.l;
	ssync;

	/*
     * Put SDRAM in self-refresh, incase anything is running
     */
    P2.H = hi(EBIU_SDGCTL);
    P2.L = lo(EBIU_SDGCTL);
    R0 = [P2];
    BITSET (R0, 24);
    [P2] = R0;
    SSYNC;

    /*
     *  Set PLL_CTL with the value that we calculate in R0
     *   - [14:09] = MSEL[5:0] : CLKIN / VCO multiplication factors
     *   - [8]     = BYPASS    : BYPASS the PLL, run CLKIN into CCLK/SCLK
     *   - [7]     = output delay (add 200ps of delay to mem signals)
     *   - [6]     = input delay (add 200ps of input delay to mem signals)
     *   - [5]     = PDWN      : 1=All Clocks off
     *   - [3]     = STOPCK    : 1=Core Clock off
     *   - [1]     = PLL_OFF   : 1=Disable Power to PLL
     *   - [0]     = DF        : 1=Pass CLKIN/2 to PLL / 0=Pass CLKIN to PLL
     *   all other bits set to zero
     */

    r0 = CONFIG_VCO_MULT & 63;      /* Load the VCO multiplier         */
    r0 = r0 << 9;                   /* Shift it over,                  */
    r1 = CONFIG_CLKIN_HALF;        /* Do we need to divide CLKIN by 2?*/
    r0 = r1 | r0;
    r1 = CONFIG_PLL_BYPASS;         /* Bypass the PLL?                 */
    r1 = r1 << 8;                   /* Shift it over                   */
    r0 = r1 | r0;                   /* add them all together           */

    p0.h = hi(PLL_CTL);
    p0.l = lo(PLL_CTL);             /* Load the address                */
    cli r2;                         /* Disable interrupts              */
	ssync;
    w[p0] = r0.l;                   /* Set the value                   */
    idle;                           /* Wait for the PLL to stablize    */
    sti r2;                         /* Enable interrupts               */

check_again:
	p0.h = hi(PLL_STAT);
	p0.l = lo(PLL_STAT);
	R0 = W[P0](Z);
	CC = BITTST(R0,5);
	if ! CC jump check_again;

	/* Configure SCLK & CCLK Dividers */
   	r0 = (CONFIG_CCLK_DIV | CONFIG_SCLK_DIV);
    p0.h = hi(PLL_DIV);
    p0.l = lo(PLL_DIV);
    w[p0] = r0.l;
    ssync;


	/*
     * We now are running at speed, time to set the Async mem bank wait states
	 * This will speed up execution, since we are normally running from FLASH.
	 */

    p2.h = (EBIU_AMBCTL1 >> 16);
    p2.l = (EBIU_AMBCTL1 & 0xFFFF);
    r0.h = (AMBCTL1VAL >> 16);
    r0.l = (AMBCTL1VAL & 0xFFFF);
    [p2] = r0;
    ssync;

    p2.h = (EBIU_AMBCTL0 >> 16);
    p2.l = (EBIU_AMBCTL0 & 0xFFFF);
    r0.h = (AMBCTL0VAL >> 16);
    r0.l = (AMBCTL0VAL & 0xFFFF);
    [p2] = r0;
    ssync;

    p2.h = (EBIU_AMGCTL >> 16);
    p2.l = (EBIU_AMGCTL & 0xffff);
    r0 = AMGCTLVAL;
    w[p2] = r0;
    ssync;

	/*
	 * Now, Initialize the SDRAM,
	 * start with the SDRAM Refresh Rate Control Register
     */
	p0.l = lo(EBIU_SDRRC);
    p0.h = hi(EBIU_SDRRC);
    r0 = mem_SDRRC;
    w[p0] = r0.l;
    ssync;

	/*
	 * SDRAM Memory Bank Control Register - bank specific parameters
	 */
	p0.l = (EBIU_SDBCTL & 0xFFFF);
	p0.h = (EBIU_SDBCTL >> 16);
	r0 = mem_SDBCTL;
	w[p0] = r0.l;
	ssync;

	/*
	 * SDRAM Global Control Register - global programmable parameters
	 * Disable self-refresh
	 */
	P2.H = hi(EBIU_SDGCTL);
    P2.L = lo(EBIU_SDGCTL);
    R0 = [P2];
    BITCLR (R0, 24);

	/*
     * Check if SDRAM is already powered up, if it is, enable self-refresh
     */
	p0.h = hi(EBIU_SDSTAT);
	p0.l = lo(EBIU_SDSTAT);
	r2.l = w[p0];
	cc = bittst(r2,3);
	if !cc jump skip;
    NOP;
	BITSET (R0, 23);
skip:
	[P2] = R0;
    SSYNC;

	/* Write in the new value in the register */
    R0.L = lo(mem_SDGCTL);
    R0.H = hi(mem_SDGCTL);
	[P2] = R0;
    SSYNC;
	nop;
	
	(P5:0) = [SP++];
	(R7:0) = [SP++];
	RETS   = [SP++];
	ASTAT  = [SP++];
	RTS;
._InitSDRAM.end:

.global _InitSDRAM;
.type _InitSDRAM,STT_FUNC;
.global ._InitSDRAM.end;
.type ._InitSDRAM.end,STT_FUNC;