lkml.org 
[lkml]   [2007]   [Aug]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patches in this message
/
From
SubjectRe: [draft] Blackfin Early Printk implmentation
Date
On Fri 17 Aug 2007 13:59, Sam Ravnborg pondered:
> That seems to explain why I could not follow your code changes.
> A more fine grained splitup would have helped here.

Sorry - see below. These aren't proper patches anymore, since it was
faster for me to split them by hand (but should be OK for review).
I will resend later properly.

> I noticed that you copied the actual early_printk code from x86_64.
> What was preventing you from just using the x86_64 code here?

Some was borrowed - but not much. since we don't support vga, or 16550 UARTs
(Blackfin has it's own on-chip UART), I don't think this would work.

> A simple
> #include <arch/x86_64/boot/early_printk.c>
> in the blackfin early_printk should do the trick.

Maybe I'm missing something - but I don't think so. Every one who implements
implements direct IO to the hardware (except me, since I put it into the driver
file, and force Sonic - the serial driver developer - to maintain it forever).

Most of the other early printks talks directly to the hardware.

> Thinking that all should do the same so maybe alpha ought to change...

When I looked at all the printk implementations, I thought they were all
kind of hokey, and not very common - but what do you want for a debug interface
that lasts less than 5 seconds?

./arch/x86_64/kernel/early_printk.c
./arch/blackfin/kernel/early_printk.c
./arch/sh64/kernel/early_printk.c
./arch/sh/kernel/early_printk.c
./arch/i386/kernel/early_printk.c
./arch/mips/kernel/early_printk.c

I didn't see an alpha implementation - where is it done?

-Robin

> So this patch does three things at least:

> -> delete cruft emulating early printk

Index: linux-2.6.x/arch/blackfin/Kconfig
===================================================================
--- linux-2.6.x/arch/blackfin/Kconfig (revision 3568)
+++ linux-2.6.x/arch/blackfin/Kconfig (working copy)
@@ -1040,24 +1040,6 @@
also relocates the irq_panic() function to L1 memory, (which is
un-cached).

-config DEBUG_KERNEL_START
- bool "Debug Kernel Startup"
- depends on DEBUG_KERNEL
- help
- Say Y here to put in an mini-execption handler before the kernel
- replaces the bootloader exception handler. This will stop kernels
- from dieing at startup with no visible error messages.
-
-config DEBUG_SERIAL_EARLY_INIT
- bool "Initialize serial driver early"
- default n
- depends on SERIAL_BFIN
- help
- Say Y here if you want to get kernel output early when kernel
- crashes before the normal console initialization. If this option
- is enable, console output will always go to the ttyBF0, no matter
- what kernel boot paramters you set.
-
config DEBUG_HUNT_FOR_ZERO
bool "Catch NULL pointer reads/writes"
default y
@@ -1165,6 +1147,20 @@
Say Y here to disable hardware tracing in some known "jumpy" pieces
of code so that the trace buffer will extend further back.

Index: linux-2.6.x/arch/blackfin/mach-bf533/head.S
===================================================================
--- linux-2.6.x/arch/blackfin/mach-bf533/head.S (revision 3568)
+++ linux-2.6.x/arch/blackfin/mach-bf533/head.S (working copy)
@@ -35,9 +35,6 @@
#include <asm/mach-common/clocks.h>
#include <asm/mach/mem_init.h>
#endif
-#if CONFIG_DEBUG_KERNEL_START
-#include <asm/mach-common/def_LPBlackfin.h>
-#endif

.global __rambase
.global __ramstart
@@ -104,36 +101,6 @@
P0 = R1;
R0 = R1;

-#if CONFIG_DEBUG_KERNEL_START
-
-/*
- * Set up a temporary Event Vector Table, so if something bad happens before
- * the kernel is fully started, it doesn't vector off into the bootloaders
- * table
- */
- P0.l = lo(EVT2);
- P0.h = hi(EVT2);
- P1.l = lo(EVT15);
- P1.h = hi(EVT15);
- P2.l = debug_kernel_start_trap;
- P2.h = debug_kernel_start_trap;
-
- RTS = P2;
- RTI = P2;
- RTX = P2;
- RTN = P2;
- RTE = P2;
-
-.Lfill_temp_vector_table:
- [P0++] = P2; /* Core Event Vector Table */
- CC = P0 == P1;
- if !CC JUMP .Lfill_temp_vector_table
- P0 = r0;
- P1 = r0;
- P2 = r0;
-
-#endif
-
p0.h = hi(FIO_MASKA_C);
p0.l = lo(FIO_MASKA_C);
r0 = 0xFFFF(Z);
@@ -519,216 +492,6 @@
RTS;
ENDPROC(_bfin_reset)

-#if CONFIG_DEBUG_KERNEL_START
-debug_kernel_start_trap:
- /* Set up a temp stack in L1 - SDRAM might not be working */
- P0.L = lo(L1_DATA_A_START + 0x100);
- P0.H = hi(L1_DATA_A_START + 0x100);
- SP = P0;
-
- /* Make sure the Clocks are the way I think they should be */
- r0 = CONFIG_VCO_MULT & 63; /* Load the VCO multiplier */
- r0 = r0 << 9; /* Shift it over, */
- r1 = CLKIN_HALF; /* Do we need to divide CLKIN by 2?*/
- r0 = r1 | r0;
- r1 = 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 */
-
-.Lcheck_again1:
- p0.h = hi(PLL_STAT);
- p0.l = lo(PLL_STAT);
- R0 = W[P0](Z);
- CC = BITTST(R0,5);
- if ! CC jump .Lcheck_again1;
-
- /* Configure SCLK & CCLK Dividers */
- r0 = (CONFIG_CCLK_ACT_DIV | CONFIG_SCLK_DIV);
- p0.h = hi(PLL_DIV);
- p0.l = lo(PLL_DIV);
- w[p0] = r0.l;
- ssync;
-
- /* Make sure UART is enabled - you can never be sure */
-
-/*
- * Setup for console. Argument comes from the menuconfig
- */
-
-#ifdef CONFIG_BAUD_9600
-#define CONSOLE_BAUD_RATE 9600
-#elif CONFIG_BAUD_19200
-#define CONSOLE_BAUD_RATE 19200
-#elif CONFIG_BAUD_38400
-#define CONSOLE_BAUD_RATE 38400
-#elif CONFIG_BAUD_57600
-#define CONSOLE_BAUD_RATE 57600
-#elif CONFIG_BAUD_115200
-#define CONSOLE_BAUD_RATE 115200
-#endif
-
- p0.h = hi(UART_GCTL);
- p0.l = lo(UART_GCTL);
- r0 = 0x00(Z);
- w[p0] = r0.L; /* To Turn off UART clocks */
- ssync;
-
- p0.h = hi(UART_LCR);
- p0.l = lo(UART_LCR);
- r0 = 0x83(Z);
- w[p0] = r0.L; /* To enable DLL writes */
- ssync;
-
- R1 = (((CONFIG_CLKIN_HZ * CONFIG_VCO_MULT) / CONFIG_SCLK_DIV) / (CONSOLE_BAUD_RATE * 16));
-
- p0.h = hi(UART_DLL);
- p0.l = lo(UART_DLL);
- r0 = 0xFF(Z);
- r0 = R1 & R0;
- w[p0] = r0.L;
- ssync;
-
- p0.h = hi(UART_DLH);
- p0.l = lo(UART_DLH);
- r1 >>= 8 ;
- w[p0] = r1.L;
- ssync;
-
- p0.h = hi(UART_GCTL);
- p0.l = lo(UART_GCTL);
- r0 = 0x0(Z);
- w[p0] = r0.L; /* To enable UART clock */
- ssync;
-
- p0.h = hi(UART_LCR);
- p0.l = lo(UART_LCR);
- r0 = 0x03(Z);
- w[p0] = r0.L; /* To Turn on UART */
- ssync;
-
- p0.h = hi(UART_GCTL);
- p0.l = lo(UART_GCTL);
- r0 = 0x01(Z);
- w[p0] = r0.L; /* To Turn on UART Clocks */
- ssync;
-
- P0.h = hi(UART_THR);
- P0.l = lo(UART_THR);
- P1.h = hi(UART_LSR);
- P1.l = lo(UART_LSR);
-
- R0.L = 'K';
- call .Lwait_char;
- R0.L='e';
- call .Lwait_char;
- R0.L='r';
- call .Lwait_char;
- R0.L='n'
- call .Lwait_char;
- R0.L='e'
- call .Lwait_char;
- R0.L='l';
- call .Lwait_char;
- R0.L=' ';
- call .Lwait_char;
- R0.L='c';
- call .Lwait_char;
- R0.L='r';
- call .Lwait_char;
- R0.L='a';
- call .Lwait_char;
- R0.L='s';
- call .Lwait_char;
- R0.L='h';
- call .Lwait_char;
- R0.L='\r';
- call .Lwait_char;
- R0.L='\n';
- call .Lwait_char;
-
- R0.L='S';
- call .Lwait_char;
- R0.L='E';
- call .Lwait_char;
- R0.L='Q'
- call .Lwait_char;
- R0.L='S'
- call .Lwait_char;
- R0.L='T';
- call .Lwait_char;
- R0.L='A';
- call .Lwait_char;
- R0.L='T';
- call .Lwait_char;
- R0.L='=';
- call .Lwait_char;
- R2 = SEQSTAT;
- call .Ldump_reg;
-
- R0.L=' ';
- call .Lwait_char;
- R0.L='R';
- call .Lwait_char;
- R0.L='E'
- call .Lwait_char;
- R0.L='T'
- call .Lwait_char;
- R0.L='X';
- call .Lwait_char;
- R0.L='=';
- call .Lwait_char;
- R2 = RETX;
- call .Ldump_reg;
-
- R0.L='\r';
- call .Lwait_char;
- R0.L='\n';
- call .Lwait_char;
-
-.Ldebug_kernel_start_trap_done:
- JUMP .Ldebug_kernel_start_trap_done;
-.Ldump_reg:
- R3 = 32;
- R4 = 0x0F;
- R5 = ':'; /* one past 9 */
-
-.Ldump_reg2:
- R0 = R2;
- R3 += -4;
- R0 >>>= R3;
- R0 = R0 & R4;
- R0 += 0x30;
- CC = R0 <= R5;
- if CC JUMP .Ldump_reg1;
- R0 += 7;
-
-.Ldump_reg1:
- R1.l = W[P1];
- CC = BITTST(R1, 5);
- if !CC JUMP .Ldump_reg1;
- W[P0] = r0;
-
- CC = R3 == 0;
- if !CC JUMP .Ldump_reg2
- RTS;
-
-.Lwait_char:
- R1.l = W[P1];
- CC = BITTST(R1, 5);
- if !CC JUMP .Lwait_char;
- W[P0] = r0;
- RTS;
-
-#endif /* CONFIG_DEBUG_KERNEL_START */
-
.data

/*
Index: linux-2.6.x/arch/blackfin/kernel/setup.c
===================================================================
--- linux-2.6.x/arch/blackfin/kernel/setup.c (revision 3568)
+++ linux-2.6.x/arch/blackfin/kernel/setup.c (working copy)
@@ -192,29 +187,6 @@
}
#endif

-#ifdef DEBUG_SERIAL_EARLY_INIT
- bfin_console_init(); /* early console registration */
- /* this give a chance to get printk() working before crash. */
-#endif
-


> -> add an early excaption handler

Index: linux-2.6.x/include/asm-blackfin/irq_handler.h
===================================================================
--- linux-2.6.x/include/asm-blackfin/irq_handler.h (revision 3568)
+++ linux-2.6.x/include/asm-blackfin/irq_handler.h (working copy)
@@ -1,3 +1,24 @@
+/*
+ * File: include/asm-blackfin/irq_handler.h
+ *
+ * Description: function prototypes for interrupt handler routines
+ *
+ * Modified:
+ * Copyright 2004-2007 Analog Devices Inc.
+ *
+ * Bugs: Enter bugs at http://blackfin.uclinux.org/
+ *
+ * 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.
+ */
+
#ifndef _IRQ_HANDLER_H
#define _IRQ_HANDLER_H

@@ -22,6 +43,7 @@
asmlinkage void init_exception_buff(void);
asmlinkage void trap_c(struct pt_regs *fp);
asmlinkage void ex_replaceable(void);
+asmlinkage void early_trap(void);

extern void *ex_table[];
extern void return_from_exception(void);
Index: linux-2.6.x/arch/blackfin/kernel/early_printk.c
===================================================================
--- linux-2.6.x/arch/blackfin/kernel/early_printk.c (revision 0)
+++ linux-2.6.x/arch/blackfin/kernel/early_printk.c (revision 0)
+/*
+ * Set up a temporary Event Vector Table, so if something bad happens before
+ * the kernel is fully started, it doesn't vector off into somewhere we don't
+ * know
+ */
+
+asmlinkage void __init init_early_exception_vectors(void)
+{
+ /* cannot program in software:
+ * evt0 - emulation (jtag)
+ * evt1 - reset
+ */
+ bfin_write_EVT2(early_trap);
+ bfin_write_EVT3(early_trap);
+ bfin_write_EVT5(early_trap);
+ bfin_write_EVT6(early_trap);
+ bfin_write_EVT7(early_trap);
+ bfin_write_EVT8(early_trap);
+ bfin_write_EVT9(early_trap);
+ bfin_write_EVT10(early_trap);
+ bfin_write_EVT11(early_trap);
+ bfin_write_EVT12(early_trap);
+ bfin_write_EVT13(early_trap);
+ bfin_write_EVT14(early_trap);
+ bfin_write_EVT15(early_trap);
+
+ /* Set all the return from interupt, exception, NMI to a known place
+ * so if we do a RETI, RETX or RETN by mistake - we go somewhere known
+ * Note - don't change RETS - we are in a subroutine, or
+ * RETE - since it might screw up if emulator is attached
+ */
+
+ asm("RETI = %0; RETX = %0; RETN = %0;\n" : : "p"(early_trap));
+}
+
+asmlinkage void __init early_trap_c(struct pt_regs *fp, void *retaddr)
+{
+ unsigned int serial_port = DEFAULT_PORT;
+ unsigned int cflag = DEFAULT_CFLAG;
+
+ /* This can happen before the uart is initialized, so initialize
+ * the UART now
+ */
+ if (!early_console_initialized) {
+ bfin_earlyserial_init(serial_port, cflag);
+ }
+
+ dump_bfin_regs(fp, retaddr);
+ dump_bfin_trace_buffer();
+
+ panic("Died early");
+}
Index: linux-2.6.x/arch/blackfin/mach-bf533/head.S
===================================================================
--- linux-2.6.x/arch/blackfin/mach-bf533/head.S (revision 3568)
+++ linux-2.6.x/arch/blackfin/mach-bf533/head.S (working copy)
@@ -214,6 +181,12 @@
fp = sp;
usp = sp;

+#ifdef CONFIG_EARLY_PRINTK
+ SP += -12;
+ call _init_early_exception_vectors;
+ SP += 12;
+#endif
+
/* Put The Code for PLL Programming and SDRAM Programming in L1 ISRAM */
call _bf53x_relocate_l1_mem;
#if CONFIG_BFIN_KERNEL_CLOCK
Index: linux-2.6.x/arch/blackfin/mach-bf561/head.S
===================================================================
--- linux-2.6.x/arch/blackfin/mach-bf561/head.S (revision 3568)
+++ linux-2.6.x/arch/blackfin/mach-bf561/head.S (working copy)
@@ -169,6 +169,12 @@
fp = sp;
usp = sp;

+#ifdef CONFIG_EARLY_PRINTK
+ SP += -12;
+ call _init_early_exception_vectors;
+ SP += 12;
+#endif
+
/* Put The Code for PLL Programming and SDRAM Programming in L1 ISRAM */
call _bf53x_relocate_l1_mem;
#if CONFIG_BFIN_KERNEL_CLOCK
Index: linux-2.6.x/arch/blackfin/mach-bf537/head.S
===================================================================
--- linux-2.6.x/arch/blackfin/mach-bf537/head.S (revision 3568)
+++ linux-2.6.x/arch/blackfin/mach-bf537/head.S (working copy)
@@ -224,6 +224,12 @@
fp = sp;
usp = sp;

+#ifdef CONFIG_EARLY_PRINTK
+ SP += -12;
+ call _init_early_exception_vectors;
+ SP += 12;
+#endif
+
/* Put The Code for PLL Programming and SDRAM Programming in L1 ISRAM */
call _bf53x_relocate_l1_mem;
#if CONFIG_BFIN_KERNEL_CLOCK
Index: linux-2.6.x/arch/blackfin/mach-bf548/head.S
===================================================================
--- linux-2.6.x/arch/blackfin/mach-bf548/head.S (revision 3568)
+++ linux-2.6.x/arch/blackfin/mach-bf548/head.S (working copy)
@@ -125,6 +125,12 @@
FP = SP;
USP = SP;

+#ifdef CONFIG_EARLY_PRINTK
+ SP += -12;
+ call _init_early_exception_vectors;
+ SP += 12;
+#endif
+
/* Put The Code for PLL Programming and SDRAM Programming in L1 ISRAM */
call _bf53x_relocate_l1_mem;
#if CONFIG_BFIN_KERNEL_CLOCK
Index: linux-2.6.x/arch/blackfin/mach-common/entry.S
===================================================================
--- linux-2.6.x/arch/blackfin/mach-common/entry.S (revision 3568)
+++ linux-2.6.x/arch/blackfin/mach-common/entry.S (working copy)
@@ -803,14 +803,57 @@
.section .l1.data.B
#endif
ENTRY(_trace_buff_offset)
- .long 0;
+ .long 0;
ALIGN
ENTRY(_software_trace_buff)
.rept ((1 << CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN)*256);
.long 0
.endr
+#endif /* CONFIG_DEBUG_BFIN_HWTRACE_EXPAND */
+
+#ifdef CONFIG_EARLY_PRINTK
+#ifdef CONFIG_EXCPT_IRQ_SYSC_L1
+.section .l1.text
+#else
+.text
#endif

+ENTRY(_early_trap)
+ SAVE_ALL_SYS
+ trace_buffer_stop(p0, r0);
+
+ /* Turn caches off, to ensure we don't get double exceptions */
+
+ P4.L = LO(IMEM_CONTROL);
+ P4.H = HI(IMEM_CONTROL);
+
+ R5 = [P4]; /* Control Register*/
+ BITCLR(R5,ENICPLB_P);
+ CLI R1;
+ SSYNC; /* SSYNC required before writing to IMEM_CONTROL. */
+ .align 8;
+ [P4] = R5;
+ SSYNC;
+
+ P4.L = LO(DMEM_CONTROL);
+ P4.H = HI(DMEM_CONTROL);
+ R5 = [P4];
+ BITCLR(R5,ENDCPLB_P);
+ SSYNC; /* SSYNC required before writing to DMEM_CONTROL. */
+ .align 8;
+ [P4] = R5;
+ SSYNC;
+ STI R1;
+
+ r0 = sp; /* stack frame pt_regs pointer argument ==> r0 */
+ r1 = RETX;
+
+ SP += -12;
+ call _early_trap_c;
+ SP += 12;
+ENDPROC(_early_trap)
+#endif /* CONFIG_EARLY_PRINTK */
+
/*
* Put these in the kernel data section - that should always be covered by
* a CPLB. This is needed to ensure we don't get double fault conditions

> -> adds early_printk





Index: linux-2.6.x/include/asm-blackfin/early_printk.h
===================================================================
--- linux-2.6.x/include/asm-blackfin/early_printk.h (revision 0)
+++ linux-2.6.x/include/asm-blackfin/early_printk.h (revision 0)
@@ -0,0 +1,28 @@
+/*
+ * File: include/asm-blackfin/early_printk.h
+ * Author: Robin Getz <rgetz@blackfin.uclinux.org
+ *
+ * Created: 14Aug2007
+ * Description: function prototpyes for early printk
+ *
+ * Modified:
+ * Copyright 2004-2007 Analog Devices Inc.
+ *
+ * Bugs: Enter bugs at http://blackfin.uclinux.org/
+ *
+ * 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.
+ */
+
+#ifdef CONFIG_EARLY_PRINTK
+extern int setup_early_printk(char *);
+#else
+#define setup_early_printk(fmt) do { } while (0)
+#endif /* CONFIG_EARLY_PRINTK */
Index: linux-2.6.x/Documentation/kernel-parameters.txt
===================================================================
--- linux-2.6.x/Documentation/kernel-parameters.txt (revision 3568)
+++ linux-2.6.x/Documentation/kernel-parameters.txt (working copy)
@@ -34,6 +34,7 @@
APIC APIC support is enabled.
APM Advanced Power Management support is enabled.
AX25 Appropriate AX.25 support is enabled.
+ BLACKFIN Blackfin architecture is enabled.
CD Appropriate CD support is enabled.
DRM Direct Rendering Management support is enabled.
EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
@@ -558,7 +559,7 @@

dtc3181e= [HW,SCSI]

- earlyprintk= [IA-32,X86-64,SH]
+ earlyprintk= [IA-32,X86-64,SH,BLACKFIN]
earlyprintk=vga
earlyprintk=serial[,ttySn[,baudrate]]

Index: linux-2.6.x/arch/blackfin/kernel/early_printk.c
===================================================================
--- linux-2.6.x/arch/blackfin/kernel/early_printk.c (revision 0)
+++ linux-2.6.x/arch/blackfin/kernel/early_printk.c (revision 0)
@@ -0,0 +1,210 @@
+/*
+ * File: arch/blackfin/kernel/early_printk.c
+ * Based on: arch/x86_64/kernel/early_printk.c
+ * Author: Robin Getz <rgetz@blackfin.uclinux.org
+ *
+ * Created: 14Aug2007
+ * Description: allow a console to be used for early printk
+ *
+ * Modified:
+ * Copyright 2004-2007 Analog Devices Inc.
+ *
+ * Bugs: Enter bugs at http://blackfin.uclinux.org/
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/serial_core.h>
+#include <linux/console.h>
+#include <linux/string.h>
+#include <asm/blackfin.h>
+#include <asm/irq_handler.h>
+#include <asm/early_printk.h>
+
+extern struct console *bfin_earlyserial_init(unsigned int port,
+ unsigned int cflag);
+extern int bfin_earlyserial_disable(void);
+
+static struct console *early_console_initialized;
+
+/* Default console
+ * Port n == ttyBFn
+ * cflags == UART output modes
+ */
+#define DEFAULT_PORT 0
+#define DEFAULT_CFLAG CS8|B57600
+
+int __init setup_early_printk(char *buf)
+{
+ int baud, bit;
+ char parity;
+ unsigned int serial_port = DEFAULT_PORT;
+ unsigned int cflag = DEFAULT_CFLAG;
+
+ /* Crashing in here would be really bad, so check both the var
+ and the pointer before we start using it
+ */
+ if (!buf)
+ return 0;
+
+ if (!*buf)
+ return 0;
+
+ if (early_console_initialized)
+ return 0;
+
+ if (!strncmp(buf, "serial", 6)) {
+ buf += 7;
+ if (!strncmp(buf, "ttyBF", 5)) {
+ buf += 5;
+ serial_port = simple_strtoul(buf, &buf, 10);
+ buf++;
+ }
+
+ cflag = 0;
+ baud = simple_strtoul(buf, &buf, 10);
+ switch (baud) {
+ case 1200:
+ cflag |= B1200;
+ break;
+ case 2400:
+ cflag |= B2400;
+ break;
+ case 4800:
+ cflag |= B4800;
+ break;
+ case 9600:
+ cflag |= B9600;
+ break;
+ case 19200:
+ cflag |= B19200;
+ break;
+ case 38400:
+ cflag |= B38400;
+ break;
+ case 115200:
+ cflag |= B115200;
+ break;
+ default:
+ cflag |= B57600;
+ }
+
+ parity = buf[0];
+ buf++;
+ switch (parity) {
+ case 'e':
+ cflag |= PARENB;
+ break;
+ case 'o':
+ cflag |= PARODD;
+ break;
+ }
+
+ bit = simple_strtoul(buf, &buf, 10);
+ switch (bit) {
+ case 5:
+ cflag |= CS5;
+ break;
+ case 6:
+ cflag |= CS5;
+ break;
+ case 7:
+ cflag |= CS5;
+ break;
+ default:
+ cflag |= CS8;
+ }
+
+ early_console_initialized = bfin_earlyserial_init(serial_port,
+ cflag);
+ } else if (!strncmp(buf, "vga", 3)) {
+ /* TODO: add framebuffer console support? */
+ }
+
+ if (early_console_initialized)
+ printk(KERN_INFO "Early Printk Support Enabled on %s%d\n",
+ early_console_initialized->name,
+ early_console_initialized->index);
+
+ return 0;
+}
+
+int __init disable_early_printk(void)
+{
+ if (!early_console_initialized)
+ return 0;
+
+ printk(KERN_INFO "Unregister %s%d\n", early_console_initialized->name,
+ early_console_initialized->index);
+ unregister_console(early_console_initialized);
+ early_console_initialized = NULL;
+ return 0;
+}
+
+late_initcall(disable_early_printk);
Based on Mike's and Gerd's earlier comments I missed (until Mike poked me),
I will move the disable_early_printk into printk.c as a common function (and
a separate patch)

Index: linux-2.6.x/arch/blackfin/kernel/Makefile
===================================================================
--- linux-2.6.x/arch/blackfin/kernel/Makefile (revision 3568)
+++ linux-2.6.x/arch/blackfin/kernel/Makefile (working copy)
@@ -15,3 +15,4 @@
obj-$(CONFIG_BFIN_DMA_5XX) += bfin_dma_5xx.o
obj-$(CONFIG_DUAL_CORE_TEST_MODULE) += dualcore_test.o
obj-$(CONFIG_KGDB) += kgdb.o
+obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
Index: linux-2.6.x/arch/blackfin/Kconfig
===================================================================
--- linux-2.6.x/arch/blackfin/Kconfig (revision 3568)
+++ linux-2.6.x/arch/blackfin/Kconfig (working copy)
@@ -1165,6 +1147,20 @@
Say Y here to disable hardware tracing in some known "jumpy" pieces
of code so that the trace buffer will extend further back.

+config EARLY_PRINTK
+ bool "Early printk"
+ default n
+ help
+ This option enables special console drivers which allow the kernel
+ to print messages very early in the bootup process.
+
+ This is useful for kernel debugging when your machine crashes very
+ early before the console code is initialized. After enabling this
+ feature, you must add "earlyprintk=serial,ttyBF0,57600" to the
+ command line (bootargs). It is safe to say Y here in all cases, as
+ all of this lives in the init section and is thrown away after the
+ kernel boots completely.
+
config DUAL_CORE_TEST_MODULE
tristate "Dual Core Test Module"
depends on (BF561)
Index: linux-2.6.x/drivers/serial/bfin_5xx.c
===================================================================
--- linux-2.6.x/drivers/serial/bfin_5xx.c (revision 3568)
+++ linux-2.6.x/drivers/serial/bfin_5xx.c (working copy)
@@ -961,31 +961,7 @@
}

#ifdef CONFIG_SERIAL_BFIN_CONSOLE
-static void bfin_serial_console_putchar(struct uart_port *port, int ch)
-{
- struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
- while (!(UART_GET_LSR(uart) & THRE))
- barrier();
- UART_PUT_CHAR(uart, ch);
- SSYNC();
-}
-
/*
- * Interrupts are disabled on entering
- */
-static void
-bfin_serial_console_write(struct console *co, const char *s, unsigned int count)
-{
- struct bfin_serial_port *uart = &bfin_serial_ports[co->index];
- int flags = 0;
-
- spin_lock_irqsave(&uart->port.lock, flags);
- uart_console_write(&uart->port, s, count, bfin_serial_console_putchar);
- spin_unlock_irqrestore(&uart->port.lock, flags);
-
-}
-
-/*
* If the port was already initialised (eg, by a boot loader),
* try to determine the current setup.
*/
@@ -1037,19 +1013,25 @@
}
pr_debug("%s:baud = %d, parity = %c, bits= %d\n", __FUNCTION__, *baud, *parity, *bits);
}
+#endif

+#if defined (CONFIG_SERIAL_BFIN_CONSOLE) || defined (CONFIG_EARLY_PRINTK)
+static struct uart_driver bfin_serial_reg;
+
static int __init
bfin_serial_console_setup(struct console *co, char *options)
{
struct bfin_serial_port *uart;
+# ifdef CONFIG_SERIAL_BFIN_CONSOLE
int baud = 57600;
int bits = 8;
int parity = 'n';
-#ifdef CONFIG_SERIAL_BFIN_CTSRTS
+# ifdef CONFIG_SERIAL_BFIN_CTSRTS
int flow = 'r';
-#else
+# else
int flow = 'n';
-#endif
+# endif
+# endif

/*
* Check whether an invalid uart number has been specified, and
@@ -1060,15 +1042,45 @@
co->index = 0;
uart = &bfin_serial_ports[co->index];

+# ifdef CONFIG_SERIAL_BFIN_CONSOLE
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
else
bfin_serial_console_get_options(uart, &baud, &parity, &bits);

return uart_set_options(&uart->port, co, baud, parity, bits, flow);
+# else
+ return 0;
+# endif
}
+#endif /* defined (CONFIG_SERIAL_BFIN_CONSOLE) ||
+ defined (CONFIG_EARLY_PRINTK) */

-static struct uart_driver bfin_serial_reg;
+#ifdef CONFIG_SERIAL_BFIN_CONSOLE
+static void bfin_serial_console_putchar(struct uart_port *port, int ch)
+{
+ struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
+ while (!(UART_GET_LSR(uart) & THRE))
+ barrier();
+ UART_PUT_CHAR(uart, ch);
+ SSYNC();
+}
+
+/*
+ * Interrupts are disabled on entering
+ */
+static void
+bfin_serial_console_write(struct console *co, const char *s, unsigned int count)
+{
+ struct bfin_serial_port *uart = &bfin_serial_ports[co->index];
+ int flags = 0;
+
+ spin_lock_irqsave(&uart->port.lock, flags);
+ uart_console_write(&uart->port, s, count, bfin_serial_console_putchar);
+ spin_unlock_irqrestore(&uart->port.lock, flags);
+
+}
+
static struct console bfin_serial_console = {
.name = BFIN_SERIAL_NAME,
.write = bfin_serial_console_write,
@@ -1094,8 +1106,70 @@
#define BFIN_SERIAL_CONSOLE &bfin_serial_console
#else
#define BFIN_SERIAL_CONSOLE NULL
+#endif /* CONFIG_SERIAL_BFIN_CONSOLE */
+
+
+#ifdef CONFIG_EARLY_PRINTK
+static __init void early_serial_putc(struct uart_port *port, int ch)
+{
+ unsigned timeout = 0xffff;
+ struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
+
+ while ((!(UART_GET_LSR(uart) & THRE)) && --timeout)
+ cpu_relax();
+ UART_PUT_CHAR(uart, ch);
+}
+
+static __init void early_serial_write(struct console *con, const char *s,
+ unsigned int n)
+{
+ struct bfin_serial_port *uart = &bfin_serial_ports[con->index];
+ unsigned int i;
+
+ for (i = 0; i < n; i++, s++) {
+ if (*s == '\n')
+ early_serial_putc(&uart->port, '\r');
+ early_serial_putc(&uart->port, *s);
+ }
+}
+
+static struct __init console bfin_early_serial_console = {
+ .name = "early_ttyBF",
+ .write = early_serial_write,
+ .device = uart_console_device,
+ .flags = CON_PRINTBUFFER | CON_BOOT,
+ .setup = bfin_serial_console_setup,
+ .index = -1,
+ .data = &bfin_serial_reg,
+};
+
+struct console __init *bfin_earlyserial_init(unsigned int port,
+ unsigned int cflag)
+{
+ struct bfin_serial_port *uart;
+ struct ktermios t;
+
+ if (port == -1 || port >= nr_ports)
+ port = 0;
+ bfin_serial_init_ports();
+ bfin_early_serial_console.index = port;
+ register_console(&bfin_early_serial_console);
+#ifdef CONFIG_KGDB_UART
+ kgdb_entry_state = 0;
+ init_kgdb_uart();
#endif
+ uart = &bfin_serial_ports[port];
+ t.c_cflag = cflag;
+ t.c_iflag = 0;
+ t.c_oflag = 0;
+ t.c_lflag = ICANON;
+ t.c_line = port;
+ bfin_serial_set_termios(&uart->port, &t, &t);
+ return &bfin_early_serial_console;
+}

+#endif /* CONFIG_SERIAL_BFIN_CONSOLE */
+
static struct uart_driver bfin_serial_reg = {
.owner = THIS_MODULE,
.driver_name = "bfin-uart",

This is a helper to the above - make sure that earlyprintk is parsed as early
as possible. Otherwise there is some time between when kernel exception table
is filled in, and early_parm is evaluated - if a crash happens between this
time, nothing will be printed out.

Index: linux-2.6.x/arch/blackfin/kernel/setup.c
===================================================================
--- linux-2.6.x/arch/blackfin/kernel/setup.c (revision 3568)
+++ linux-2.6.x/arch/blackfin/kernel/setup.c (working copy)
@@ -44,6 +44,7 @@
#include <asm/blackfin.h>
#include <asm/cplbinit.h>
#include <asm/fixed_code.h>
+#include <asm/early_printk.h>

u16 _bfin_swrst;

@@ -134,7 +135,6 @@
unsigned int memsize;
for (;;) {
if (c == ' ') {
-
if (!memcmp(to, "mem=", 4)) {
to += 4;
memsize = memparse(to, &to);
@@ -157,8 +157,10 @@
1;
}
}
+ } else if (!memcmp(to, "earlyprintk=", 12)) {
+ to += 12;
+ setup_early_printk(to);
}
-
}
c = *(to++);
if (!c)
@@ -177,14 +179,7 @@
#ifdef CONFIG_DUMMY_CONSOLE
conswitchp = &dummy_con;
#endif
- cclk = get_cclk();
- sclk = get_sclk();

-#if !defined(CONFIG_BFIN_KERNEL_CLOCK)
- if (ANOMALY_05000273 && cclk == sclk)
- panic("ANOMALY 05000273, SCLK can not be same as CCLK");
-#endif
-
#ifdef BF561_FAMILY
if (ANOMALY_05000266) {
bfin_read_IMDMA_D0_IRQ_STATUS();
@@ -192,29 +187,6 @@
}
#endif

-#ifdef DEBUG_SERIAL_EARLY_INIT
- bfin_console_init(); /* early console registration */
- /* this give a chance to get printk() working before crash. */
-#endif
-
- printk(KERN_INFO "Hardware Trace ");
- if (bfin_read_TBUFCTL() & 0x1 )
- printk("Active ");
- else
- printk("Off ");
- if (bfin_read_TBUFCTL() & 0x2)
- printk("and Enabled\n");
- else
- printk("and Disabled\n");
-
-
-#if defined(CONFIG_CHR_DEV_FLASH) || defined(CONFIG_BLK_DEV_FLASH)
- /* we need to initialize the Flashrom device here since we might
- * do things with flash early on in the boot
- */
- flash_probe();
-#endif
-
#if defined(CONFIG_CMDLINE_BOOL)
strncpy(&command_line[0], CONFIG_CMDLINE, sizeof(command_line));
command_line[sizeof(command_line) - 1] = 0;
@@ -229,8 +201,36 @@
physical_mem_end = 0;
_ramend = CONFIG_MEM_SIZE * 1024 * 1024;

+ /* We parse command line early, to set memory limits and get
+ * early_printk earlier than normal
+ */
parse_cmdline_early(&command_line[0]);

+#if defined(CONFIG_CHR_DEV_FLASH) || defined(CONFIG_BLK_DEV_FLASH)
+ /* we need to initialize the Flashrom device here since we might
+ * do things with flash early on in the boot
+ */
+ flash_probe();
+#endif
+
+ cclk = get_cclk();
+ sclk = get_sclk();
+
+#if !defined(CONFIG_BFIN_KERNEL_CLOCK)
+ if (ANOMALY_05000273 && cclk < (sclk *2))
+ panic("ANOMALY 05000273: CCLK must be >= 2*SCLK ");
+#endif
+
+ printk(KERN_INFO "Hardware Trace ");
+ if (bfin_read_TBUFCTL() & 0x1 )
+ printk("Active ");
+ else
+ printk("Off ");
+ if (bfin_read_TBUFCTL() & 0x2)
+ printk("and Enabled\n");
+ else
+ printk("and Disabled\n");
+
if (physical_mem_end == 0)
physical_mem_end = _ramend;

@@ -298,13 +298,16 @@
* 05000263 - Hardware loop corrupted when taking an ICPLB exception
*/
#if (defined(CONFIG_DEBUG_HUNT_FOR_ZERO))
- if (memory_end >= 56 * 1024 * 1024)
+ if (memory_end >= 56 * 1024 * 1024) {
memory_end = 56 * 1024 * 1024;
+ printk(KERN_NOTICE "Warning: limiting memory to %liMB due to hardware anomaly 05000263\n", memory_end >> 20);
+ }
#else
- if (memory_end >= 60 * 1024 * 1024)
+ if (memory_end >= 60 * 1024 * 1024) {
memory_end = 60 * 1024 * 1024;
+ printk(KERN_NOTICE "Warning: limiting memory to %liMB due to hardware anomaly 05000263\n", memory_end >> 20);
+ }
#endif /* CONFIG_DEBUG_HUNT_FOR_ZERO */
- printk(KERN_NOTICE "Warning: limiting memory to %liMB due to hardware anomaly 05000263\n", memory_end >> 20);
#endif /* ANOMALY_05000263 */

#if !defined(CONFIG_MTD_UCLINUX)
@@ -340,9 +343,6 @@
printk(KERN_INFO "Processor Speed: %lu MHz core clock and %lu Mhz System Clock\n",
cclk / 1000000, sclk / 1000000);

- if (ANOMALY_05000273 && (cclk >> 1) <= sclk)
- printk("\n\n\nANOMALY_05000273: CCLK must be >= 2*SCLK !!!\n\n\n");
-
printk(KERN_INFO "Board Memory: %ldMB\n", physical_mem_end >> 20);
printk(KERN_INFO "Kernel Managed Memory: %ldMB\n", _ramend >> 20);

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-08-17 22:11    [from the cache]
©2003-2011 Jasper Spaans