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authorwdenk <wdenk>2002-11-03 00:24:07 +0000
committerwdenk <wdenk>2002-11-03 00:24:07 +0000
commitc609719b8d1b2dca590e0ed499016d041203e403 (patch)
tree7ea1755d80903ff972f312a249eb856061d40e15 /board/w7o/post1.S
parent5b1d713721c3ea02549940133f09236783dda1f9 (diff)
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+/*
+ * (C) Copyright 2001
+ * Bill Hunter, Wave 7 Optics, william.hunter@mediaone.net
+ * and
+ * Erik Theisen, Wave 7 Optics, etheisen@mindspring.com
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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 program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+/*
+ * Description:
+ * Routine to exercise memory for the bringing up of our boards.
+ */
+#include <config.h>
+#include <ppc4xx.h>
+
+#define _LINUX_CONFIG_H 1 /* avoid reading Linux autoconf.h file */
+
+#include <ppc_asm.tmpl>
+#include <ppc_defs.h>
+
+#include <asm/cache.h>
+#include <asm/mmu.h>
+
+#include <watchdog.h>
+
+#include "errors.h"
+
+#define _ASMLANGUAGE
+
+ .globl test_sdram
+ .globl test_led
+ .globl log_stat
+ .globl log_warn
+ .globl log_err
+ .globl temp_uart_init
+ .globl post_puts
+ .globl disp_hex
+
+/*****************************************************
+******* Text Strings for low level printing ******
+******* In section got2 *******
+*****************************************************/
+
+/*
+ * Define the text strings for errors and warnings.
+ * Switch to .data section.
+ */
+ .section ".data"
+err_str: .asciz "*** POST ERROR = "
+warn_str: .asciz "*** POST WARNING = "
+end_str: .asciz "\r\n"
+
+/*
+ * Enter the labels in Global Entry Table (GOT).
+ * Switch to .got2 section.
+ */
+ START_GOT
+ GOT_ENTRY(err_str)
+ GOT_ENTRY(warn_str)
+ GOT_ENTRY(end_str)
+ END_GOT
+
+/*
+ * Switch back to .text section.
+ */
+ .text
+
+/****************************************
+ ****************************************
+ ******** LED register test ********
+ ****************************************
+ ***************************************/
+test_led:
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -12(r1) /* Save back chain and move SP */
+ stw r0, +16(r1) /* Save link register */
+ stw r4, +8(r1) /* save R4 */
+
+ WATCHDOG_RESET /* Reset the watchdog */
+
+ addi r3, 0, ERR_FF /* first test value is ffff */
+ addi r4, r3, 0 /* save copy of pattern */
+ bl set_led /* store first test value */
+ bl get_led /* read it back */
+ xor. r4, r4, r3 /* compare to original */
+#if defined(CONFIG_W7OLMC)
+ andi. r4, r4, 0x00ff /* lmc has 8 bits */
+#else
+ andi. r4, r4, 0xffff /* lmg has 16 bits */
+#endif
+ beq LED2 /* next test */
+ addi r3, 0, ERR_LED /* error code = 1 */
+ bl log_err /* display error and halt */
+LED2: addi r3, 0, ERR_00 /* 2nd test value is 0000 */
+ addi r4, r3, 0 /* save copy of pattern */
+ bl set_led /* store first test value */
+ bl get_led /* read it back */
+ xor. r4, r4, r3 /* compare to original */
+#if defined(CONFIG_W7OLMC)
+ andi. r4, r4, 0x00ff /* lmc has 8 bits */
+#else
+ andi. r4, r4, 0xffff /* lmg has 16 bits */
+#endif
+ beq LED3 /* next test */
+ addi r3, 0, ERR_LED /* error code = 1 */
+ bl log_err /* display error and halt */
+
+LED3: /* restore stack and return */
+ lwz r0, +16(r1) /* Get saved link register */
+ mtlr r0 /* Restore link register */
+ lwz r4, +8(r1) /* restore r4 */
+ addi r1, r1, +12 /* Remove frame from stack */
+ blr /* Return to calling function */
+
+/****************************************
+ ****************************************
+ ******** SDRAM TESTS ********
+ ****************************************
+ ***************************************/
+test_sdram:
+ /* called with mem size in r3 */
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -16(r1) /* Save back chain and move SP */
+ stw r0, +20(r1) /* Save link register */
+ stmw r30, +8(r1) /* save R30,R31 */
+ /* r30 is log2(mem size) */
+ /* r31 is mem size */
+
+ /* take log2 of total mem size */
+ addi r31, r3, 0 /* save total mem size */
+ addi r30, 0, 0 /* clear r30 */
+l2_loop:
+ srwi. r31, r31, 1 /* shift right 1 */
+ addi r30, r30, 1 /* count shifts */
+ bne l2_loop /* loop till done */
+ addi r30, r30, -1 /* correct for over count */
+ addi r31, r3, 0 /* save original size */
+
+ /* now kick the dog and test the mem */
+ WATCHDOG_RESET /* Reset the watchdog */
+ bl Data_Buster /* test crossed/shorted data lines */
+ addi r3, r30, 0 /* get log2(memsize) */
+ addi r4, r31, 0 /* get memsize */
+ bl Ghost_Buster /* test crossed/shorted addr lines */
+ addi r3, r31, 0 /* get mem size */
+ bl Bit_Buster /* check for bad internal bits */
+
+ /* restore stack and return */
+ lmw r30, +8(r1) /* Restore r30, r31 */
+ lwz r0, +20(r1) /* Get saved link register */
+ mtlr r0 /* Restore link register */
+ addi r1, r1, +16 /* Remove frame from stack */
+ blr /* Return to calling function */
+
+
+/****************************************
+ ******** sdram data bus test ********
+ ***************************************/
+Data_Buster:
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -24(r1) /* Save back chain and move SP */
+ stw r0, +28(r1) /* Save link register */
+ stmw r28, 8(r1) /* save r28 - r31 on stack */
+ /* r31 i/o register */
+ /* r30 sdram base address */
+ /* r29 5555 syndrom */
+ /* r28 aaaa syndrom */
+
+ /* set up led register for this test */
+ addi r3, 0, ERR_RAMG /* set led code to 1 */
+ bl log_stat /* store test value */
+ /* now test the dram data bus */
+ xor r30, r30, r30 /* load r30 with base addr of sdram */
+ addis r31, 0, 0x5555 /* load r31 with test value */
+ ori r31, r31, 0x5555
+ stw r31,0(r30) /* sto the value */
+ lwz r29,0(r30) /* read it back */
+ xor r29,r31,r29 /* compare it to original */
+ addis r31, 0, 0xaaaa /* load r31 with test value */
+ ori r31, r31, 0xaaaa
+ stw r31,0(r30) /* sto the value */
+ lwz r28,0(r30) /* read it back */
+ xor r28,r31,r28 /* compare it to original */
+ or r3,r28,r29 /* or together both error terms */
+ /*
+ * Now that we have the error bits,
+ * we have to decide which part they are in.
+ */
+ bl get_idx /* r5 is now index to error */
+ addi r3, r3, ERR_RAMG
+ cmpwi r3, ERR_RAMG /* check for errors */
+ beq db_done /* skip if no errors */
+ bl log_err /* log the error */
+
+db_done:
+ lmw r28, 8(r1) /* restore r28 - r31 from stack */
+ lwz r0, +28(r1) /* Get saved link register */
+ addi r1, r1, +24 /* Remove frame from stack */
+ mtlr r0 /* Restore link register */
+ blr /* Return to calling function */
+
+
+/****************************************************
+ ******** test for address ghosting in dram ********
+ ***************************************************/
+
+Ghost_Buster:
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -36(r1) /* Save back chain and move SP */
+ stw r0, +40(r1) /* Save link register */
+ stmw r25, 8(r1) /* save r25 - r31 on stack */
+ /* r31 = scratch register */
+ /* r30 is main referance loop counter,
+ 0 to 23 */
+ /* r29 is ghost loop count, 0 to 22 */
+ /* r28 is referance address */
+ /* r27 is ghost address */
+ /* r26 is log2 (mem size) =
+ number of byte addr bits */
+ /* r25 is mem size */
+
+ /* save the log2(mem size) and mem size */
+ addi r26, r3, 0 /* r26 is number of byte addr bits */
+ addi r25, r4, 0 /* r25 is mem size in bytes */
+
+ /* set the leds for address ghost test */
+ addi r3, 0, ERR_ADDG
+ bl set_led
+
+ /* first fill memory with zeros */
+ srwi r31, r25, 2 /* convert bytes to longs */
+ mtctr r31 /* setup byte counter */
+ addi r28, 0, 0 /* start at address at 0 */
+ addi r31, 0, 0 /* data value = 0 */
+clr_loop:
+ stw r31, 0(r28) /* Store zero value */
+ addi r28, r28, 4 /* Increment to next word */
+ andi. r27, r28, 0xffff /* check for 2^16 loops */
+ bne clr_skip /* if not there, then skip */
+ WATCHDOG_RESET /* kick the dog every now and then */
+clr_skip:
+ bdnz clr_loop /* Round and round... */
+
+ /* now do main test */
+ addi r30, 0, 0 /* start referance counter at 0 */
+outside:
+ /*
+ * Calculate the referance address
+ * the referance address is calculated by setting the (r30-1)
+ * bit of the base address
+ * when r30=0, the referance address is the base address.
+ * thus the sequence 0,1,2,4,8,..,2^(n-1)
+ * setting the bit is done with the following shift functions.
+ */
+ WATCHDOG_RESET /* Reset the watchdog */
+
+ addi r31, 0, 1 /* r31 = 1 */
+ slw r28, r31, r30 /* set bit coresponding to loop cnt */
+ srwi r28, r28, 1 /* then shift it right one so */
+ /* we start at location 0 */
+ /* fill referance address with Fs */
+ addi r31, 0, 0x00ff /* r31 = one byte of set bits */
+ stb r31,0(r28) /* save ff in referance address */
+
+ /* ghost (inner) loop, now check all posible ghosted addresses */
+ addi r29, 0, 0 /* start ghosted loop counter at 0 */
+inside:
+ /*
+ * Calculate the ghost address by flipping one
+ * bit of referance address. This gives the
+ * sequence 1,2,4,8,...,2^(n-1)
+ */
+ addi r31, 0, 1 /* r31 = 1 */
+ slw r27, r31, r29 /* set bit coresponding to loop cnt */
+ xor r27, r28, r27 /* ghost address = ref addr with
+ bit flipped*/
+
+ /* now check for ghosting */
+ lbz r31,0(r27) /* get content of ghost addr */
+ cmpwi r31, 0 /* compare read value to 0 */
+ bne Casper /* we found a ghost! */
+
+ /* now close ghost ( inner ) loop */
+ addi r29, r29, 1 /* increment inner loop counter */
+ cmpw r29, r26 /* check for last inner loop */
+ blt inside /* do more inner loops */
+
+ /* now close referance ( outer ) loop */
+ addi r31, 0, 0 /* r31 = zero */
+ stb r31, 0(28) /* zero out the altered address loc. */
+ /*
+ * Increment and check for end, count is zero based.
+ * With the ble, this gives us one more loops than
+ * address bits for sequence 0,1,2,4,8,...2^(n-1)
+ */
+ addi r30, r30, 1 /* increment outer loop counter */
+ cmpw r30, r26 /* check for last inner loop */
+ ble outside /* do more outer loops */
+
+ /* were done, lets go home */
+ b gb_done
+Casper: /* we found a ghost !! */
+ addi r3, 0, ERR_ADDF /* get indexed error message */
+ bl log_err /* log error led error code */
+gb_done: /* pack your bags, and go home */
+ lmw r25, 8(r1) /* restore r25 - r31 from stack */
+ lwz r0, +40(r1) /* Get saved link register */
+ addi r1, r1, +36 /* Remove frame from stack */
+ mtlr r0 /* Restore link register */
+ blr /* Return to calling function */
+
+/****************************************************
+ ******** SDRAM data fill tests **********
+ ***************************************************/
+Bit_Buster:
+ /* called with mem size in r3 */
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -16(r1) /* Save back chain and move SP */
+ stw r0, +20(r1) /* Save link register */
+ stw r4, +8(r1) /* save R4 */
+ stw r5, +12(r1) /* save r5 */
+
+ addis r5, r3, 0 /* save mem size */
+
+ /* Test 55555555 */
+ addi r3, 0, ERR_R55G /* set up error code in case we fail */
+ bl log_stat /* store test value */
+ addis r4, 0, 0x5555
+ ori r4, r4, 0x5555
+ bl fill_test
+
+ /* Test aaaaaaaa */
+ addi r3, 0, ERR_RAAG /* set up error code in case we fail */
+ bl log_stat /* store test value */
+ addis r4, 0, 0xAAAA
+ ori r4, r4, 0xAAAA
+ bl fill_test
+
+ /* Test 00000000 */
+ addi r3, 0, ERR_R00G /* set up error code in case we fail */
+ bl log_stat /* store test value */
+ addis r4, 0, 0
+ ori r4, r4, 0
+ bl fill_test
+
+ /* restore stack and return */
+ lwz r5, +12(r1) /* restore r4 */
+ lwz r4, +8(r1) /* restore r4 */
+ lwz r0, +20(r1) /* Get saved link register */
+ addi r1, r1, +16 /* Remove frame from stack */
+ mtlr r0 /* Restore link register */
+ blr /* Return to calling function */
+
+
+
+/****************************************************
+ ******** fill test ********
+ ***************************************************/
+/* tests memory by filling with value, and reading back */
+/* r5 = Size of memory in bytes */
+/* r4 = Value to write */
+/* r3 = Error code */
+fill_test:
+ mflr r0 /* Get link register */
+ stwu r1, -32(r1) /* Save back chain and move SP */
+ stw r0, +36(r1) /* Save link register */
+ stmw r27, 8(r1) /* save r27 - r31 on stack */
+ /* r31 - scratch register */
+ /* r30 - memory address */
+ mr r27, r3
+ mr r28, r4
+ mr r29, r5
+
+ WATCHDOG_RESET /* Reset the watchdog */
+
+ /* first fill memory with Value */
+ srawi r31, r29, 2 /* convert bytes to longs */
+ mtctr r31 /* setup counter */
+ addi r30, 0, 0 /* Make r30 = addr 0 */
+ft_0: stw r28, 0(r30) /* Store value */
+ addi r30, r30, 4 /* Increment to next word */
+ andi. r31, r30, 0xffff /* check for 2^16 loops */
+ bne ft_0a /* if not there, then skip */
+ WATCHDOG_RESET /* kick the dog every now and then */
+ft_0a: bdnz ft_0 /* Round and round... */
+
+ WATCHDOG_RESET /* Reset the watchdog */
+
+ /* Now confirm Value is in memory */
+ srawi r31, r29, 2 /* convert bytes to longs */
+ mtctr r31 /* setup counter */
+ addi r30, 0, 0 /* Make r30 = addr 0 */
+ft_1: lwz r31, 0(r30) /* get value from memory */
+ xor. r31, r31, r28 /* Writen = Read ? */
+ bne ft_err /* If bad, than halt */
+ addi r30, r30, 4 /* Increment to next word */
+ andi. r31, r30, 0xffff /* check for 2^16 loops*/
+ bne ft_1a /* if not there, then skip */
+ WATCHDOG_RESET /* kick the dog every now and then */
+ft_1a: bdnz ft_1 /* Round and round... */
+
+ WATCHDOG_RESET /* Reset the watchdog */
+
+ b fill_done /* restore and return */
+
+ft_err: addi r29, r27, 0 /* save current led code */
+ addi r27, r31, 0 /* get pattern in r27 */
+ bl get_idx /* get index from r27 */
+ add r27, r27, r29 /* add index to old led code */
+ bl log_err /* output led err code, halt CPU */
+
+fill_done:
+ lmw r27, 8(r1) /* restore r27 - r31 from stack */
+ lwz r0, +36(r1) /* Get saved link register */
+ addi r1, r1, +32 /* Remove frame from stack */
+ mtlr r0 /* Restore link register */
+ blr /* Return to calling function */
+
+
+/****************************************************
+ ******* get error index from r3 pattern ********
+ ***************************************************/
+get_idx: /* r3 = (MSW(r3) !=0)*2 +
+ (LSW(r3) !=0) */
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -12(r1) /* Save back chain and move SP */
+ stw r0, +16(r1) /* Save link register */
+ stw r4, +8(r1) /* save R4 */
+
+ andi. r4, r3, 0xffff /* check for lower bits */
+ beq gi2 /* skip if no bits set */
+ andis. r4, r3, 0xffff /* check for upper bits */
+ beq gi3 /* skip if no bits set */
+ addi r3, 0, 3 /* both upper and lower bits set */
+ b gi_done
+gi2: andis. r4, r3, 0xffff /* check for upper bits*/
+ beq gi4 /* skip if no bits set */
+ addi r3, 0, 2 /* only upper bits set */
+ b gi_done
+gi3: addi r3, 0, 1 /* only lower bits set */
+ b gi_done
+gi4: addi r3, 0, 0 /* no bits set */
+gi_done:
+ /* restore stack and return */
+ lwz r0, +16(r1) /* Get saved link register */
+ mtlr r0 /* Restore link register */
+ lwz r4, +8(r1) /* restore r4 */
+ addi r1, r1, +12 /* Remove frame from stack */
+ blr /* Return to calling function */
+
+/****************************************************
+ ******** set LED to R5 and hang ********
+ ***************************************************/
+log_stat: /* output a led code and continue */
+set_led:
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -12(r1) /* Save back chain and move SP */
+ stw r0, +16(r1) /* Save link register */
+ stw r4, +8(r1) /* save R4 */
+
+ addis r4, 0, 0xfe00 /* LED buffer is at 0xfe000000 */
+#if defined(CONFIG_W7OLMG) /* only on gateway, invert outputs */
+ xori r3,r3, 0xffff /* complement led code, active low */
+ sth r3, 0(r4) /* store first test value */
+ xori r3,r3, 0xffff /* complement led code, active low */
+#else /* if not gateway, then don't invert */
+ sth r3, 0(r4) /* store first test value */
+#endif
+
+ /* restore stack and return */
+ lwz r0, +16(r1) /* Get saved link register */
+ mtlr r0 /* Restore link register */
+ lwz r4, +8(r1) /* restore r4 */
+ addi r1, r1, +12 /* Remove frame from stack */
+ blr /* Return to calling function */
+
+get_led:
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -12(r1) /* Save back chain and move SP */
+ stw r0, +16(r1) /* Save link register */
+ stw r4, +8(r1) /* save R4 */
+
+ addis r4, 0, 0xfe00 /* LED buffer is at 0xfe000000 */
+ lhz r3, 0(r4) /* store first test value */
+#if defined(CONFIG_W7OLMG) /* only on gateway, invert inputs */
+ xori r3,r3, 0xffff /* complement led code, active low */
+#endif
+
+ /* restore stack and return */
+ lwz r0, +16(r1) /* Get saved link register */
+ mtlr r0 /* Restore link register */
+ lwz r4, +8(r1) /* restore r4 */
+ addi r1, r1, +12 /* Remove frame from stack */
+ blr /* Return to calling function */
+
+log_err: /* output the error and hang the board ( for now ) */
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -12(r1) /* Save back chain and move SP */
+ stw r0, +16(r1) /* Save link register */
+ stw r3, +8(r1) /* save a copy of error code */
+ bl set_led /* set the led pattern */
+ GET_GOT /* get GOT address in r14 */
+ lwz r3,GOT(err_str) /* get address of string */
+ bl post_puts /* output the warning string */
+ lwz r3, +8(r1) /* get error code */
+ addi r4, 0, 2 /* set disp length to 2 nibbles */
+ bl disp_hex /* output the error code */
+ lwz r3,GOT(end_str) /* get address of string */
+ bl post_puts /* output the warning string */
+halt:
+ b halt /* hang */
+
+ /* restore stack and return */
+ lwz r0, +16(r1) /* Get saved link register */
+ mtlr r0 /* Restore link register */
+ addi r1, r1, +12 /* Remove frame from stack */
+ blr /* Return to calling function */
+
+log_warn: /* output a warning, then continue with operations */
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -16(r1) /* Save back chain and move SP */
+ stw r0, +20(r1) /* Save link register */
+ stw r3, +8(r1) /* save a copy of error code */
+ stw r14, +12(r1) /* save a copy of r14 (used by GOT) */
+
+ bl set_led /* set the led pattern */
+ GET_GOT /* get GOT address in r14 */
+ lwz r3,GOT(warn_str) /* get address of string */
+ bl post_puts /* output the warning string */
+ lwz r3, +8(r1) /* get error code */
+ addi r4, 0, 2 /* set disp length to 2 nibbles */
+ bl disp_hex /* output the error code */
+ lwz r3,GOT(end_str) /* get address of string */
+ bl post_puts /* output the warning string */
+
+ addis r3, 0, 64 /* has a long delay */
+ mtctr r3
+log_2:
+ WATCHDOG_RESET /* this keeps dog from barking, */
+ /* and takes time */
+ bdnz log_2 /* loop till time expires */
+
+ /* restore stack and return */
+ lwz r0, +20(r1) /* Get saved link register */
+ lwz r14, +12(r1) /* restore r14 */
+ mtlr r0 /* Restore link register */
+ addi r1, r1, +16 /* Remove frame from stack */
+ blr /* Return to calling function */
+
+/*******************************************************************
+ * temp_uart_init
+ * Temporary UART initialization routine
+ * Sets up UART0 to run at 9600N81 off of the internal clock.
+ * R3-R4 are used.
+ ******************************************************************/
+temp_uart_init:
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -8(r1) /* Save back chain and move SP */
+ stw r0, +12(r1) /* Save link register */
+
+ addis r3, 0, 0xef60
+ ori r3, r3, 0x0303 /* r3 = UART0_LCR */
+ addi r4, 0, 0x83 /* n81 format, divisor regs enabled */
+ stb r4, 0(r3)
+
+ /* set baud rate to use internal clock,
+ baud = (200e6/16)/31/42 = 9600 */
+
+ addis r3, 0, 0xef60 /* Address of baud divisor reg */
+ ori r3, r3, 0x0300 /* UART0_DLM */
+ addi r4, 0, +42 /* uart baud divisor LSB = 93 */
+ stb r4, 0(r3) /* baud = (200 /16)/14/93 */
+
+ addi r3, r3, 0x0001 /* uart baud divisor addr */
+ addi r4, 0, 0
+ stb r4, 0(r3) /* Divisor Latch MSB = 0 */
+
+ addis r3, 0, 0xef60
+ ori r3, r3, 0x0303 /* r3 = UART0_LCR */
+ addi r4, 0, 0x03 /* n81 format, tx/rx regs enabled */
+ stb r4, 0(r3)
+
+ /* output a few line feeds */
+ addi r3, 0, '\n' /* load line feed */
+ bl post_putc /* output the char */
+ addi r3, 0, '\n' /* load line feed */
+ bl post_putc /* output the char */
+
+ /* restore stack and return */
+ lwz r0, +12(r1) /* Get saved link register */
+ mtlr r0 /* Restore link register */
+ addi r1, r1, +8 /* Remove frame from stack */
+ blr /* Return to calling function */
+
+/**********************************************************************
+ ** post_putc
+ ** outputs charactor in R3
+ ** r3 returns the error code ( -1 if there is an error )
+ *********************************************************************/
+
+post_putc:
+
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -20(r1) /* Save back chain and move SP */
+ stw r0, +24(r1) /* Save link register */
+ stmw r29, 8(r1) /* save r29 - r31 on stack
+ r31 - uart base address
+ r30 - delay counter
+ r29 - scratch reg */
+
+ addis r31, 0, 0xef60 /* Point to uart base */
+ ori r31, r31, 0x0300
+ addis r30, 0, 152 /* Load about 10,000,000 ticks. */
+pputc_lp:
+ lbz r29, 5(r31) /* Read Line Status Register */
+ andi. r29, r29, 0x20 /* Check THRE status */
+ bne thre_set /* Branch if FIFO empty */
+ addic. r30, r30, -1 /* Decrement and check if empty. */
+ bne pputc_lp /* Try, try again */
+ addi r3, 0, -1 /* Load error code for timeout */
+ b pputc_done /* Bail out with error code set */
+thre_set:
+ stb r3, 0(r31) /* Store character to UART */
+ addi r3, 0, 0 /* clear error code */
+pputc_done:
+ lmw r29, 8(r1) /*restore r29 - r31 from stack */
+ lwz r0, +24(r1) /* Get saved link register */
+ addi r1, r1, +20 /* Remove frame from stack */
+ mtlr r0 /* Restore link register */
+ blr /* Return to calling function */
+
+
+/****************************************************************
+ post_puts
+ Accepts a null-terminated string pointed to by R3
+ Outputs to the serial port until 0x00 is found.
+ r3 returns the error code ( -1 if there is an error )
+*****************************************************************/
+post_puts:
+
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -12(r1) /* Save back chain and move SP */
+ stw r0, +16(r1) /* Save link register */
+ stw r31, 8(r1) /* save r31 - char pointer */
+
+ addi r31, r3, 0 /* move pointer to R31 */
+pputs_nxt:
+ lbz r3, 0(r31) /* Get next character */
+ addic. r3, r3, 0 /* Check for zero */
+ beq pputs_term /* bail out if zero */
+ bl post_putc /* output the char */
+ addic. r3, r3, 0 /* check for error */
+ bne pputs_err
+ addi r31, r31, 1 /* point to next char */
+ b pputs_nxt /* loop till term */
+pputs_err:
+ addi r3, 0, -1 /* set error code */
+ b pputs_end /* were outa here */
+pputs_term:
+ addi r3, 0, 1 /* set success code */
+ /* restore stack and return */
+pputs_end:
+ lwz r31, 8(r1) /* restore r27 - r31 from stack */
+ lwz r0, +16(r1) /* Get saved link register */
+ addi r1, r1, +12 /* Remove frame from stack */
+ mtlr r0 /* Restore link register */
+ blr /* Return to calling function */
+
+
+
+/********************************************************************
+ ***** disp_hex
+ ***** Routine to display a hex value from a register.
+ ***** R3 is value to display
+ ***** R4 is number of nibbles to display ie 2 for byte 8 for (long)word
+ ***** Returns -1 in R3 if there is an error ( ie serial port hangs )
+ ***** Returns 0 in R3 if no error
+ *******************************************************************/
+disp_hex:
+ /* save the return info on stack */
+ mflr r0 /* Get link register */
+ stwu r1, -16(r1) /* Save back chain and move SP */
+ stw r0, +20(r1) /* Save link register */
+ stmw r30, 8(r1) /* save r30 - r31 on stack */
+ /* r31 output char */
+ /* r30 uart base address */
+ addi r30, 0, 8 /* Go through 8 nibbles. */
+ addi r31, r3, 0
+pputh_nxt:
+ rlwinm r31, r31, 4, 0, 31 /* Rotate next nibble into position */
+ andi. r3, r31, 0x0f /* Get nibble. */
+ addi r3, r3, 0x30 /* Add zero's ASCII code. */
+ cmpwi r3, 0x03a
+ blt pputh_out
+ addi r3, r3, 0x07 /* 0x27 for lower case. */
+pputh_out:
+ cmpw r30, r4
+ bgt pputh_skip
+ bl post_putc
+ addic. r3, r3, 0 /* check for error */
+ bne pputh_err
+pputh_skip:
+ addic. r30, r30, -1
+ bne pputh_nxt
+ xor r3, r3, r3 /* Clear error code */
+ b pputh_done
+pputh_err:
+ addi r3, 0, -1 /* set error code */
+pputh_done:
+ /* restore stack and return */
+ lmw r30, 8(r1) /* restore r30 - r31 from stack */
+ lwz r0, +20(r1) /* Get saved link register */
+ addi r1, r1, +16 /* Remove frame from stack */
+ mtlr r0 /* Restore link register */
+ blr /* Return to calling function */
+