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Diffstat (limited to 'cpu/blackfin/start.S')
| -rw-r--r-- | cpu/blackfin/start.S | 219 |
1 files changed, 219 insertions, 0 deletions
diff --git a/cpu/blackfin/start.S b/cpu/blackfin/start.S new file mode 100644 index 000000000..30212e928 --- /dev/null +++ b/cpu/blackfin/start.S @@ -0,0 +1,219 @@ +/* + * U-boot - start.S Startup file for Blackfin u-boot + * + * Copyright (c) 2005-2007 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 + L1_SRAM_SCRATCH_SIZE); + sp.h = HI(L1_SRAM_SCRATCH + L1_SRAM_SCRATCH_SIZE); + +#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 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; + +#if (CONFIG_BFIN_BOOT_MODE == BFIN_BOOT_BYPASS) + /* 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 and setup our async banks. + */ + /* XXX: we should DMA this into L1, put external memory into + * self refresh, and then jump there ... + */ + call _get_pc; + r3 = 0x0; + r3.h = 0x2000; + cc = r0 < r3 (iu); + if cc jump .Lproc_initialized; + + serial_early_puts("Program Clocks"); + + call _initcode; + + /* Since we reprogrammed SCLK, we need to update the serial divisor */ + serial_early_set_baud + +.Lproc_initialized: +#endif + + /* 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); + + /* Relocate from wherever are (FLASH/RAM/etc...) to the + * hardcoded monitor location in the end of RAM. + */ + serial_early_puts("Relocate"); + call _get_pc; +.Loffset: + r2.l = .Loffset; + r2.h = .Loffset; + r3.l = _start; + r3.h = _start; + r1 = r2 - r3; + + r0 = r0 - r1; + + cc = r0 == r3; + if cc jump .Lnorelocate; + + r6 = 0 (x); + p1 = r0; + + p2.l = LO(CFG_MONITOR_BASE); + p2.h = HI(CFG_MONITOR_BASE); + + p3 = 0x04; + p4.l = LO(CFG_MONITOR_BASE + CFG_MONITOR_LEN); + p4.h = HI(CFG_MONITOR_BASE + CFG_MONITOR_LEN); +.Lloop1: + r1 = [p1 ++ p3]; + [p2 ++ p3] = r1; + cc=p2==p4; + if !cc jump .Lloop1; + + /* 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 */ + r0.h = HI(CONFIG_STACKBASE); + r0.l = LO(CONFIG_STACKBASE); + sp = r0; + 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 "board_init_f", 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. + */ + serial_early_puts("Lower to 15"); + r0 = r7; + r1 = r6; + p0.l = LO(EVT15); + p0.h = HI(EVT15); + p1.l = _cpu_init_f; + p1.h = _cpu_init_f; + [p0] = p1; + p2.l = LO(IMASK); + p2.h = HI(IMASK); + p3.l = LO(EVT_IVG15); + p3.h = HI(EVT_IVG15); + [p2] = p3; + raise 15; + p4.l = .LWAIT_HERE; + p4.h = .LWAIT_HERE; + reti = p4; + rti; + +.LWAIT_HERE: + jump .LWAIT_HERE; +ENDPROC(_start) + +LENTRY(_get_pc) + r0 = rets; +#if ANOMALY_05000371 + NOP; + NOP; + NOP; +#endif + rts; +ENDPROC(_get_pc) |