cpu/blackfin/start.S - platform/external/u-boot - Gitiles

 /*
  * U-boot - start.S Startup file for Blackfin u-boot
  *
  * Copyright (c) 2005-2008 Analog Devices Inc.
  *
  * This file is based on head.S
  * Copyright (c) 2003  Metrowerks/Motorola
  * Copyright (C) 1998  D. Jeff Dionne <jeff@ryeham.ee.ryerson.ca>,
  *                     Kenneth Albanowski <kjahds@kjahds.com>,
  *                     The Silver Hammer Group, Ltd.
  * (c) 1995, Dionne & Associates
  * (c) 1995, DKG Display Tech.
  *
  * 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., 51 Franklin St, Fifth Floor, Boston,
  * MA 02110-1301 USA
  */

 #include <config.h>
 #include <asm/blackfin.h>
 #include <asm/mach-common/bits/core.h>
 #include <asm/mach-common/bits/dma.h>
 #include <asm/mach-common/bits/pll.h>

 #include "serial.h"

 /* It may seem odd that we make calls to functions even though we haven't
  * relocated ourselves yet out of {flash,ram,wherever}.  This is OK because
  * the "call" instruction in the Blackfin architecture is actually PC
  * relative.  So we can call functions all we want and not worry about them
  * not being relocated yet.
  */

 .text
 ENTRY(_start)

 	/* Set our initial stack to L1 scratch space */
 	sp.l = LO(L1_SRAM_SCRATCH_END - 20);
 	sp.h = HI(L1_SRAM_SCRATCH_END - 20);

 #ifdef CONFIG_HW_WATCHDOG
 # ifndef CONFIG_HW_WATCHDOG_TIMEOUT_START
 #  define CONFIG_HW_WATCHDOG_TIMEOUT_START 5000
 # endif
 	/* Program the watchdog with an initial timeout of ~5 seconds.
 	 * That should be long enough to bootstrap ourselves up and
 	 * then the common u-boot code can take over.
 	 */
 	P0.L = LO(WDOG_CNT);
 	P0.H = HI(WDOG_CNT);
 	R0.L = 0;
 	R0.H = HI(MSEC_TO_SCLK(CONFIG_HW_WATCHDOG_TIMEOUT_START));
 	[P0] = R0;
 	/* fire up the watchdog - R0.L above needs to be 0x0000 */
 	W[P0 + (WDOG_CTL - WDOG_CNT)] = R0;
 #endif

 	/* Turn on the serial for debugging the init process */
 	serial_early_init
 	serial_early_set_baud

 	serial_early_puts("Init Registers");

 	/* Disable self-nested interrupts and enable CYCLES for udelay() */
 	R0 = CCEN | 0x30;
 	SYSCFG = R0;

 	/* Zero out registers required by Blackfin ABI.
 	 * http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
 	 */
 	r1 = 0 (x);
 	/* Disable circular buffers */
 	l0 = r1;
 	l1 = r1;
 	l2 = r1;
 	l3 = r1;
 	/* Disable hardware loops in case we were started by 'go' */
 	lc0 = r1;
 	lc1 = r1;

 	/* Save RETX so we can pass it while booting Linux */
 	r7 = RETX;

 	/* Figure out where we are currently executing so that we can decide
 	 * how to best reprogram and relocate things.  We'll pass below:
 	 *  R4: load address of _start
 	 *  R5: current (not load) address of _start
 	 */
 	serial_early_puts("Find ourselves");

 	call _get_pc;
 .Loffset:
 	r1.l = .Loffset;
 	r1.h = .Loffset;
 	r4.l = _start;
 	r4.h = _start;
 	r3 = r1 - r4;
 	r5 = r0 - r3;

 	/* Inform upper layers if we had to do the relocation ourselves.
 	 * This allows us to detect whether we were loaded by 'go 0x1000'
 	 * or by the bootrom from an LDR.  "R6" is "loaded_from_ldr".
 	 */
 	r6 = 1 (x);
 	cc = r4 == r5;
 	if cc jump .Lnorelocate;
 	r6 = 0 (x);

 	/* In bypass mode, we don't have an LDR with an init block
 	 * so we need to explicitly call it ourselves.  This will
 	 * reprogram our clocks, memory, and setup our async banks.
 	 */
 	serial_early_puts("Program Clocks");

 	/* if we're executing >=0x20000000, then we dont need to dma */
 	r3 = 0x0;
 	r3.h = 0x2000;
 	cc = r5 < r3 (iu);
 	if cc jump .Ldma_and_reprogram;
 	call _initcode;
 	jump .Lprogrammed;

 	/* we're sitting in external memory, so dma into L1 and reprogram */
 .Ldma_and_reprogram:
 	r0.l = LO(L1_INST_SRAM);
 	r0.h = HI(L1_INST_SRAM);
 	r1.l = __initcode_start;
 	r1.h = __initcode_start;
 	r2.l = __initcode_end;
 	r2.h = __initcode_end;
 	r2 = r2 - r1;	/* convert r2 into length of initcode */
 	r1 = r1 - r4;	/* convert r1 from load address of initcode ... */
 	r1 = r1 + r5;	/* ... to current (not load) address of initcode */
 	p3 = r0;
 	call _dma_memcpy_nocache;
 	call (p3);

 	/* Since we reprogrammed SCLK, we need to update the serial divisor */
 .Lprogrammed:
 	serial_early_set_baud

 	/* Relocate from wherever we are (FLASH/RAM/etc...) to the hardcoded
 	 * monitor location in the end of RAM.  We know that memcpy() only
 	 * uses registers, so it is safe to call here.  Note that this only
 	 * copies to external memory ... we do not start executing out of
 	 * it yet (see "lower to 15" below).
 	 */
 	serial_early_puts("Relocate");
 	r0 = r4;
 	r1 = r5;
 	r2.l = LO(CONFIG_SYS_MONITOR_LEN);
 	r2.h = HI(CONFIG_SYS_MONITOR_LEN);
 	call _memcpy_ASM;

 	/* Initialize BSS section ... we know that memset() does not
 	 * use the BSS, so it is safe to call here.  The bootrom LDR
 	 * takes care of clearing things for us.
 	 */
 	serial_early_puts("Zero BSS");
 	r0.l = __bss_start;
 	r0.h = __bss_start;
 	r1 = 0 (x);
 	r2.l = __bss_end;
 	r2.h = __bss_end;
 	r2 = r2 - r0;
 	call _memset;

 .Lnorelocate:

 	/* Setup the actual stack in external memory */
 	sp.h = HI(CONFIG_STACKBASE);
 	sp.l = LO(CONFIG_STACKBASE);
 	fp = sp;

 	/* Now lower ourselves from the highest interrupt level to
 	 * the lowest.  We do this by masking all interrupts but 15,
 	 * setting the 15 handler to ".Lenable_nested", raising the 15
 	 * interrupt, and then returning from the highest interrupt
 	 * level to the dummy "jump" until the interrupt controller
 	 * services the pending 15 interrupt.  If executing out of
 	 * flash, these steps also changes the code flow from flash
 	 * to external memory.
 	 */
 	serial_early_puts("Lower to 15");
 	r0 = r7;
 	r1 = r6;
 	p0.l = LO(EVT15);
 	p0.h = HI(EVT15);
 	p1.l = .Lenable_nested;
 	p1.h = .Lenable_nested;
 	[p0] = p1;
 	r7 = EVT_IVG15 (z);
 	sti r7;
 	raise 15;
 	p4.l = .LWAIT_HERE;
 	p4.h = .LWAIT_HERE;
 	reti = p4;
 	rti;

 	/* Enable nested interrupts before continuing with cpu init */
 .Lenable_nested:
 	cli r7;
 	[--sp] = reti;
 	jump.l _cpu_init_f;

 .LWAIT_HERE:
 	jump .LWAIT_HERE;
 ENDPROC(_start)

 LENTRY(_get_pc)
 	r0 = rets;
 #if ANOMALY_05000371
 	NOP;
 	NOP;
 	NOP;
 #endif
 	rts;
 ENDPROC(_get_pc)
	/*
	* U-boot - start.S Startup file for Blackfin u-boot
	*
	* Copyright (c) 2005-2008 Analog Devices Inc.
	*
	* This file is based on head.S
	* Copyright (c) 2003 Metrowerks/Motorola
	* Copyright (C) 1998 D. Jeff Dionne <jeff@ryeham.ee.ryerson.ca>,
	* Kenneth Albanowski <kjahds@kjahds.com>,
	* The Silver Hammer Group, Ltd.
	* (c) 1995, Dionne & Associates
	* (c) 1995, DKG Display Tech.
	*
	* 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., 51 Franklin St, Fifth Floor, Boston,
	* MA 02110-1301 USA
	*/

	#include <config.h>
	#include <asm/blackfin.h>
	#include <asm/mach-common/bits/core.h>
	#include <asm/mach-common/bits/dma.h>
	#include <asm/mach-common/bits/pll.h>

	#include "serial.h"

	/* It may seem odd that we make calls to functions even though we haven't
	* relocated ourselves yet out of {flash,ram,wherever}. This is OK because
	* the "call" instruction in the Blackfin architecture is actually PC
	* relative. So we can call functions all we want and not worry about them
	* not being relocated yet.
	*/

	.text
	ENTRY(_start)

	/* Set our initial stack to L1 scratch space */
	sp.l = LO(L1_SRAM_SCRATCH_END - 20);
	sp.h = HI(L1_SRAM_SCRATCH_END - 20);

	#ifdef CONFIG_HW_WATCHDOG
	# ifndef CONFIG_HW_WATCHDOG_TIMEOUT_START
	# define CONFIG_HW_WATCHDOG_TIMEOUT_START 5000
	# endif
	/* Program the watchdog with an initial timeout of ~5 seconds.
	* That should be long enough to bootstrap ourselves up and
	* then the common u-boot code can take over.
	*/
	P0.L = LO(WDOG_CNT);
	P0.H = HI(WDOG_CNT);
	R0.L = 0;
	R0.H = HI(MSEC_TO_SCLK(CONFIG_HW_WATCHDOG_TIMEOUT_START));
	[P0] = R0;
	/* fire up the watchdog - R0.L above needs to be 0x0000 */
	W[P0 + (WDOG_CTL - WDOG_CNT)] = R0;
	#endif

	/* Turn on the serial for debugging the init process */
	serial_early_init
	serial_early_set_baud

	serial_early_puts("Init Registers");

	/* Disable self-nested interrupts and enable CYCLES for udelay() */
	R0 = CCEN \| 0x30;
	SYSCFG = R0;

	/* Zero out registers required by Blackfin ABI.
	* http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
	*/
	r1 = 0 (x);
	/* Disable circular buffers */
	l0 = r1;
	l1 = r1;
	l2 = r1;
	l3 = r1;
	/* Disable hardware loops in case we were started by 'go' */
	lc0 = r1;
	lc1 = r1;

	/* Save RETX so we can pass it while booting Linux */
	r7 = RETX;

	/* Figure out where we are currently executing so that we can decide
	* how to best reprogram and relocate things. We'll pass below:
	* R4: load address of _start
	* R5: current (not load) address of _start
	*/
	serial_early_puts("Find ourselves");

	call _get_pc;
	.Loffset:
	r1.l = .Loffset;
	r1.h = .Loffset;
	r4.l = _start;
	r4.h = _start;
	r3 = r1 - r4;
	r5 = r0 - r3;

	/* Inform upper layers if we had to do the relocation ourselves.
	* This allows us to detect whether we were loaded by 'go 0x1000'
	* or by the bootrom from an LDR. "R6" is "loaded_from_ldr".
	*/
	r6 = 1 (x);
	cc = r4 == r5;
	if cc jump .Lnorelocate;
	r6 = 0 (x);

	/* In bypass mode, we don't have an LDR with an init block
	* so we need to explicitly call it ourselves. This will
	* reprogram our clocks, memory, and setup our async banks.
	*/
	serial_early_puts("Program Clocks");

	/* if we're executing >=0x20000000, then we dont need to dma */
	r3 = 0x0;
	r3.h = 0x2000;
	cc = r5 < r3 (iu);
	if cc jump .Ldma_and_reprogram;
	call _initcode;
	jump .Lprogrammed;

	/* we're sitting in external memory, so dma into L1 and reprogram */
	.Ldma_and_reprogram:
	r0.l = LO(L1_INST_SRAM);
	r0.h = HI(L1_INST_SRAM);
	r1.l = __initcode_start;
	r1.h = __initcode_start;
	r2.l = __initcode_end;
	r2.h = __initcode_end;
	r2 = r2 - r1; /* convert r2 into length of initcode */
	r1 = r1 - r4; /* convert r1 from load address of initcode ... */
	r1 = r1 + r5; /* ... to current (not load) address of initcode */
	p3 = r0;
	call _dma_memcpy_nocache;
	call (p3);

	/* Since we reprogrammed SCLK, we need to update the serial divisor */
	.Lprogrammed:
	serial_early_set_baud

	/* Relocate from wherever we are (FLASH/RAM/etc...) to the hardcoded
	* monitor location in the end of RAM. We know that memcpy() only
	* uses registers, so it is safe to call here. Note that this only
	* copies to external memory ... we do not start executing out of
	* it yet (see "lower to 15" below).
	*/
	serial_early_puts("Relocate");
	r0 = r4;
	r1 = r5;
	r2.l = LO(CONFIG_SYS_MONITOR_LEN);
	r2.h = HI(CONFIG_SYS_MONITOR_LEN);
	call _memcpy_ASM;

	/* Initialize BSS section ... we know that memset() does not
	* use the BSS, so it is safe to call here. The bootrom LDR
	* takes care of clearing things for us.
	*/
	serial_early_puts("Zero BSS");
	r0.l = __bss_start;
	r0.h = __bss_start;
	r1 = 0 (x);
	r2.l = __bss_end;
	r2.h = __bss_end;
	r2 = r2 - r0;
	call _memset;

	.Lnorelocate:

	/* Setup the actual stack in external memory */
	sp.h = HI(CONFIG_STACKBASE);
	sp.l = LO(CONFIG_STACKBASE);
	fp = sp;

	/* Now lower ourselves from the highest interrupt level to
	* the lowest. We do this by masking all interrupts but 15,
	* setting the 15 handler to ".Lenable_nested", raising the 15
	* interrupt, and then returning from the highest interrupt
	* level to the dummy "jump" until the interrupt controller
	* services the pending 15 interrupt. If executing out of
	* flash, these steps also changes the code flow from flash
	* to external memory.
	*/
	serial_early_puts("Lower to 15");
	r0 = r7;
	r1 = r6;
	p0.l = LO(EVT15);
	p0.h = HI(EVT15);
	p1.l = .Lenable_nested;
	p1.h = .Lenable_nested;
	[p0] = p1;
	r7 = EVT_IVG15 (z);
	sti r7;
	raise 15;
	p4.l = .LWAIT_HERE;
	p4.h = .LWAIT_HERE;
	reti = p4;
	rti;

	/* Enable nested interrupts before continuing with cpu init */
	.Lenable_nested:
	cli r7;
	[--sp] = reti;
	jump.l _cpu_init_f;

	.LWAIT_HERE:
	jump .LWAIT_HERE;
	ENDPROC(_start)

	LENTRY(_get_pc)
	r0 = rets;
	#if ANOMALY_05000371
	NOP;
	NOP;
	NOP;
	#endif
	rts;
	ENDPROC(_get_pc)