[U-Boot-Users] Patch: Nios gdb/jtag support

26 Apr 2004

Add Nios GDB/JTAG Console support:
   - Add stubs to support gdb via JTAG.
   - Add support for console over JTAG.
   - Minor cleanup.
diff -Naurb u-boot-2004APR25/CHANGELOG nios-jtag-gdb/CHANGELOG

--- u-boot-2004APR25/CHANGELOG	2004-04-25 14:48:28.000000000 -0400
+++ nios-jtag-gdb/CHANGELOG	2004-04-25 17:48:56.000000000 -0400
@@ -2,6 +2,11 @@
 Changes for U-Boot 1.1.1:
 ======================================================================
+* Add Nios GDB/JTAG Console support, Scott McNutt, 25 Apr 2004:
+  - Add stubs to support gdb via JTAG.
+  - Add support for console over JTAG.
+  - Minor cleanup.
+
 * Clean up the TQM8xx_YYMHz configurations; allow to use the same
   binary image for all clok frequencies. Implement run-time
   optimization of flash access timing based on the actual bus
diff -Naurb u-boot-2004APR25/board/altera/dk1c20/vectors.S nios-jtag-gdb/board/altera/dk1c20/vectors.S
--- u-boot-2004APR25/board/altera/dk1c20/vectors.S	2004-01-03 14:43:48.000000000 -0500
+++ nios-jtag-gdb/board/altera/dk1c20/vectors.S	2004-04-25 16:27:21.000000000 -0400
@@ -38,6 +38,8 @@
  *	_cwp_lolimit	-Handles register window underflows.
  *	_cwp_hilimit	-Handles register window overflows.
  *	_timebase_int	-Increments the timebase.
+ *	_brkpt_hw_int	-Hardware breakpoint handler.
+ *	_brkpt_sw_int	-Software breakpoint handler.
  *	_def_xhandler	-Default exception handler.
  *
  * _timebase_int handles a Nios Timer interrupt and increments the
@@ -58,9 +60,8 @@
    .long	_def_xhandler@h		/* Vector 0  - NMI */
    .long	_cwp_lolimit@h		/* Vector 1  -  underflow */
    .long	_cwp_hilimit@h		/* Vector 2  - overflow	*/
-
-	.long	_def_xhandler@h		/* Vector 3 - GNUPro debug */
-	.long	_def_xhandler@h		/* Vector 4 - GNUPro debug */
+	.long	_brkpt_hw_int@h		/* Vector 3 - Breakpoint */
+	.long	_brkpt_sw_int@h		/* Vector 4 - Single step*/
    .long	_def_xhandler@h		/* Vector 5 - GNUPro debug */
    .long	_def_xhandler@h		/* Vector 6 - future reserved */
    .long	_def_xhandler@h		/* Vector 7 - future reserved */
diff -Naurb u-boot-2004APR25/config.mk nios-jtag-gdb/config.mk
--- u-boot-2004APR25/config.mk	2004-03-13 18:29:44.000000000 -0500
+++ nios-jtag-gdb/config.mk	2004-04-25 19:23:54.000000000 -0400
@@ -126,7 +126,7 @@
 # this option have to be placed behind -Wall -- that's why it is here
 ifeq ($(ARCH),nios)
 ifeq ($(findstring 2.9,$(shell $(CC) --version)),2.9)
-CFLAGS := $(CPPFLAGS) -Wno-trigraphs
+CFLAGS := $(CPPFLAGS) -Wall -Wno-trigraphs
 endif
 endif
diff -Naurb u-boot-2004APR25/cpu/nios/interrupts.c nios-jtag-gdb/cpu/nios/interrupts.c
--- u-boot-2004APR25/cpu/nios/interrupts.c	2004-02-23 18:54:50.000000000 -0500
+++ nios-jtag-gdb/cpu/nios/interrupts.c	2004-04-25 15:44:11.000000000 -0400
@@ -179,7 +179,7 @@
    int vec;
printf ("\nInterrupt-Information:\n");
-	printf ("Nr  Routine   Arg       CouIt's ok to cnt\n");
+	printf ("Nr  Routine   Arg       Count\n");
for (vec=0; vec<64; vec++) {
    	if (irq_vecs[vec].handler != NULL) {
diff -Naurb u-boot-2004APR25/cpu/nios/serial.c nios-jtag-gdb/cpu/nios/serial.c
--- u-boot-2004APR25/cpu/nios/serial.c	2004-02-23 18:54:50.000000000 -0500
+++ nios-jtag-gdb/cpu/nios/serial.c	2004-04-25 16:10:06.000000000 -0400
@@ -26,6 +26,48 @@
 #include <watchdog.h>
 #include <nios-io.h>
+/*------------------------------------------------------------------
+ * JTAG acts as the serial port
+ *-----------------------------------------------------------------*/
+#if defined(CONFIG_CONSOLE_JTAG)
+
+static nios_jtag_t *jtag = (nios_jtag_t *)CFG_NIOS_CONSOLE;
+
+void serial_setbrg( void ){ return; }
+int serial_init( void ) { return(0);}
+
+void serial_putc (char c)
+{
+	while ((jtag->txcntl & NIOS_JTAG_TRDY) != 0)
+		WATCHDOG_RESET ();
+	jtag->txcntl = NIOS_JTAG_TRDY | (unsigned char)c;
+}
+
+void serial_puts (const char *s)
+{
+	while (*s != 0)
+		serial_putc (*s++);
+}
+
+int serial_tstc (void)
+{
+	return (jtag->rxcntl & NIOS_JTAG_RRDY);
+}
+
+int serial_getc (void)
+{
+	int c;
+	while (serial_tstc() == 0)
+		WATCHDOG_RESET ();
+	c = jtag->rxcntl & 0x0ff;
+	jtag->rxcntl = 0;
+	return (c);
+}
+
+/*------------------------------------------------------------------
+ * UART the serial port
+ *-----------------------------------------------------------------*/
+#else
static nios_uart_t *uart = (nios_uart_t *)CFG_NIOS_CONSOLE;
@@ -34,12 +76,12 @@
 /* Everything's already setup for fixed-baud PTF
  * assignment
  */
-void serial_setbrg( void ){ return; }
-int serial_init( void ) { return(0);}
+void serial_setbrg (void){ return; }
+int serial_init (void) { return (0);}
#else
-void serial_setbrg( void )
+void serial_setbrg (void)
 {
    DECLARE_GLOBAL_DATA_PTR;
    unsigned div;
@@ -49,39 +91,44 @@
    return;
 }
-int serial_init( void )
+int serial_init (void)
 {
-	serial_setbrg();
-	return(0);
+	serial_setbrg ();
+	return (0);
 }
#endif /* CFG_NIOS_FIXEDBAUD */
-void serial_putc( char c )
+/*-----------------------------------------------------------------------
+ * UART CONSOLE
+ *---------------------------------------------------------------------*/
+void serial_putc (char c)
 {
    if (c == '\n')
-		serial_putc('\r');
-	while( (uart->status & NIOS_UART_TRDY) == 0 )
+		serial_putc ('\r');
+	while ((uart->status & NIOS_UART_TRDY) == 0)
    	WATCHDOG_RESET ();
    uart->txdata = (unsigned char)c;
 }
-void serial_puts( const char *s )
+void serial_puts (const char *s)
 {
-	while( *s != 0 ) {
-		serial_putc( *s++ );
+	while (*s != 0) {
+		serial_putc (*s++);
    }
 }
-int serial_tstc( void )
+int serial_tstc (void)
 {
-	return( uart->status & NIOS_UART_RRDY);
+	return (uart->status & NIOS_UART_RRDY);
 }
-int serial_getc( void )
+int serial_getc (void)
 {
-	while( serial_tstc() == 0 )
+	while (serial_tstc () == 0)
    	WATCHDOG_RESET ();
    return( uart->rxdata & 0x00ff );
 }
+
+#endif /* CONFIG_JTAG_CONSOLE */
diff -Naurb u-boot-2004APR25/cpu/nios/start.S nios-jtag-gdb/cpu/nios/start.S
--- u-boot-2004APR25/cpu/nios/start.S	2003-10-08 19:26:14.000000000 -0400
+++ nios-jtag-gdb/cpu/nios/start.S	2004-04-25 15:44:11.000000000 -0400
@@ -93,6 +93,14 @@
    subi	%g6, 4			/* %g6 <- src addr */
    ld	%g7, [%g7]		/* %g7 <- dst addr */
+	/* No need to move text sections if we're already located
+	 * at the proper address.
+	 */
+	cmp	%g7, %g6
+	ifs	cc_z
+	br	reloc
+	nop				/* delay slot */
+	
 1:	cmp	%g7, %g5
    skps	cc_nz
    br	2f
@@ -114,6 +122,7 @@
     pfx	%xhi(reloc@h)
     movhi	%g0, %xlo(reloc@h)
     jmp	%g0
+	 nop				/* delay slot */
 reloc:
/*
@@ -141,6 +150,48 @@
 4:
/*
+	 * INIT VECTOR TABLE
+	 */
+	pfx	%hi(CFG_VECT_BASE)
+	movi	%g0, %lo(CFG_VECT_BASE)	
+	pfx	%xhi(CFG_VECT_BASE)
+	movhi	%g0, %xlo(CFG_VECT_BASE)	/* dst */
+	mov	%l0, %g0
+
+	pfx	%hi(_vectors)
+	movi	%g1, %lo(_vectors)	
+	pfx	%xhi(_vectors)
+	movhi	%g1, %xlo(_vectors)	/* src */
+	bgen	%g2, 6			/* cnt = 64 */
+
+	ldp	%g3, [%l0, 3]		/* bkpt vector */
+	ldp	%g4, [%l0, 4]		/* single step vector */
+	
+5:	ld	%g7, [%g1]
+	addi	%g1, 4			/* src++ */
+	st	[%g0], %g7
+	addi	%g0, 4			/* dst++ */
+
+	subi	%g2, 1			/* cnt-- */
+	ifrnz	%g2
+	br	5b
+	nop				/* delay slot */
+
+#if defined(CONFIG_ROM_STUBS)
+	/* Restore the breakpoint and single step exception
+	 * vectors to their original values.
+	 */
+	stp	[%l0,3], %g3		/* breakpoint */
+	stp	[%l0,4], %g4		/* single step */
+#endif
+
+	/* For debug startup convenience ... software breakpoints
+	 * set prior to this point may not succeed ;-)
+	 */
+	.global __start
+__start:
+
+	/*
     * Call board_init -- never returns
     */
    pfx	%hi(board_init@h)
diff -Naurb u-boot-2004APR25/cpu/nios/traps.S nios-jtag-gdb/cpu/nios/traps.S
--- u-boot-2004APR25/cpu/nios/traps.S	2003-10-08 19:26:14.000000000 -0400
+++ nios-jtag-gdb/cpu/nios/traps.S	2004-04-25 15:44:11.000000000 -0400
@@ -557,3 +557,26 @@
    mov	%fp, %sp
tret	%o7			/* Done */
+
+/*************************************************************************
+ * GDB stubs
+ ************************************************************************/
+	.text
+	.global _brkpt_hw_int, _brkpt_sw_int
+	.align	4
+	
+_brkpt_hw_int:
+	movi	%l1, 9
+	pfx	3
+	wrctl	%l1
+	pfx	4
+	wrctl	%l1
+	
+_brkpt_sw_int:
+	movi	%l1, 9
+	pfx	3
+	wrctl	%l1
+	pfx	4
+	wrctl	%l1
+
+	tret	%o7
diff -Naurb u-boot-2004APR25/doc/README.nios nios-jtag-gdb/doc/README.nios
--- u-boot-2004APR25/doc/README.nios	2004-02-23 17:22:32.000000000 -0500
+++ nios-jtag-gdb/doc/README.nios	2004-04-25 17:36:18.000000000 -0400
@@ -55,6 +55,12 @@
 a problem as little, if any, of the Altera source contains
 features that are not already available in U-Boot.
+1.3 Debugging via OCI
+---------------------
+The Nios port supports debugging with gdb and/or nios-console
+via the JTAG port. Stubs for debugging with gdb via the serial
+port are not currently implemented.
+
2. CONFIGURATION OPTIONS/SETTINGS
 ----------------------------------
@@ -79,7 +85,11 @@
CONFIG_NIOS -- defined for all Nios-32 boards.
-CFG_NIOS_CONSOLE -- the base address of the console UART.
+CFG_NIOS_CONSOLE -- the base address of the console UART or the JTAG
+	stdio port. To enable a console via JTAG, define
+	CONFIG_CONSOLE_JTAG and set CGF_NIOS_CONSOLE to the base address
+	of the JTAG stdio port (normally OCI base + 0x00fa). Then
+	run nios-console with the -w option.
    (standard-32: nasys_uart_0 resp. na_uart1_base).
CFG_NIOS_FIXEDBAUD -- defined if the console UART PTF fixed_baud
@@ -176,20 +186,109 @@
     3. Release CFG_NIOS_CPU_BUTTON_PIO, button number 0.
-5. BRAIN DAMAGE
+5. DEBUGGING WITH GDB
+---------------------
+
+Debug sessions using gdb are currently supported only via JTAG. The
+stubs for debugging via a serial port are not implemented. To enable
+the gdb JTAG stubs, simply reference _brkpt_hw_int and _brkpt_sw_int
+at vector table offsets 3 and 4, respectively. For an example, see
+board/altera/dk1c20/vectors.S.
+
+5.1 Vector Table Initialization and ROM Stubs
+---------------------------------------------
+If CONFIG_ROM_STUBS is defined, the debug breakpoint and single step
+entries in the vector table are restored to their initial values
+immediately _after_ initializing the vector table. Defining this macro
+is useful when ROM-based stubs are implemented.
+
+NOTE: The default GERMS monitor does NOT implement gdb stubs, nor does
+it initialize the vector table. Therefore, when debugging U-Boot, you
+should NOT set a software breakpoint prior to vector table initialization.
+
+5.2 Starting a Debug Session
+----------------------------
+If you're not familiar with gdb, you follow these step-by-step instructions.
+These instructions are NOT the only way to start a debug session, but they
+cover most of the individual functions to get you started.
+
+	1.  Start the JTAG gdb server. Open a Nios shell window and start
+	the server. When the server is started you must provide the base
+	address of the OCI core. For example, when using the Cyclone
+	development kit (DK1C20):
+	
+		$ nios-gdb-server --ocibase=0x00920800 --tcpport=2342
+	
+	2.  Start gdb. Open a Nios shell window, change to the top-level
+	U-Boot directory and start gdb, specifying the u-boot elf file:
+
+		$ nios-elf-gdb u-boot
+	
+	3.  Update target settings. From the file menu, select
+	"Target Settings ..." and select the following, then click 'Ok':
+
+		Target:	Remote/TCP
+		Port :	2342   (same as in step 1)
+		Display download dialog: checked
+		All other check boxes: unchecked
+		
+	4.  Connect to the target. Select menu: 'Run->Connect to target'.
+	You should see a dialog box indicating the you successfully connected
+	to the target.
+
+	5.  Download U-Boot. Select menu: 'Run->Download'.
+
+	6.  Open a gdb console window and set the source directory paths.
+	Select menu: 'View->Console'. In the console window, enter the
+	following commands, then close the console window:
+
+		(gdb) directory common
+		(gdb) directory cpu/nios
+		(gdb) directory lib_nios
+		(gdb) directory board/altera/dk1c20
+	
+	Note that the last command is for the DK1C20 board only. If you
+	are using another board, specify that board's directory.
+
+	7.  Open the file board.c (using the file menu in the lower
+	left hand corner). Scroll to the board_init() routine and set
+	a breakpoint.
+
+	8. Run U-Boot. Just click on the run icon, or select menu:
+	'Run->Run'. U-Boot should start running, then break at your
+	breakpoint.
+
+	9.  Have fun & start learning more about gdb.
+	
+
+5.3 For advanced Users
+----------------------
+A few notes for those more familiar with gdb.
+
+	-Serial port stubs are not implemented. Sorry, but it's just not
+	worth _my_ effort. The JTAG stubs work great and are ridiculously
+	simple to implement.
+
+	-If you need to debug the early startup code (prior to the vector
+	table initialization), use the nios-console debugger.
+
+	- Connect, download & run -- there are some problems here. Connect
+	download and run seperately to avoid trouble.
+	
+6. BRAIN DAMAGE
 ----------------
This section describes some of the unfortunate and avoidable aspects
 of working with the Nios CPU ... and some things you can do to
 reduce your pain.
-5.1 GERMS doesn't work with Hyperterminal
+6.1 GERMS doesn't work with Hyperterminal
 ------------------------------------------
 GERMS doesn't do CR/LF mapping that is compatible with Hyperterminal
 (or minicom) -- geez. Regardless of you opion of Hyperterminal, this
 sad design decision is remedied by using U-Boot.
-5.2 cygwin Incompatibility
+6.2 cygwin Incompatibility
 ---------------------------
 The version of cygwin distributed with the nios GNUPro toolchain is
 out-of-date and incompatible with the latest cygwin distributions.
@@ -202,7 +301,7 @@
 The solution ... well, you can wait for Altera ... or build as
 set of tools for linux.
-5.3 No native gcc
+6.3 No native gcc
 ------------------
 I'm not sure how this one slipped through the cracks ... but it is
 a real pain. Basically, if you want to build anything for the native
@@ -215,7 +314,7 @@
 toolchain can it found in the CDK4NIOS project hosted by Source
 Forge at http://cdk4nios.sourceforge.net.
-5.4 Can't build default U-Boot
+6.4 Can't build default U-Boot
 -------------------------------
 By default, when you build U-Boot you will be building some native
 tools along with the target elf, bin, and srec files. Without a
@@ -232,15 +331,16 @@
    	-c -o $@ environment.c
With:
-environment.o: environment.c ../tools/envcrc
+environment.o: environment.c
    $(CC) $(AFLAGS) -Wa,--no-warn \
    	-DENV_CRC=0 \
    	-c -o $@ environment.c
-BTW, thats a 'zero' ... not the letter 'O'.
+BTW, thats a 'zero' ... not the letter 'O'. And not that the
+"../tools/envcrc" dependency is removed.
-6. HELP WANTED
+7. HELP WANTED
 ---------------
There are plenty of areas where help is needed. Here's are some ideas
diff -Naurb u-boot-2004APR25/examples/Makefile nios-jtag-gdb/examples/Makefile
--- u-boot-2004APR25/examples/Makefile	2004-04-18 17:13:44.000000000 -0400
+++ nios-jtag-gdb/examples/Makefile	2004-04-25 15:44:11.000000000 -0400
@@ -38,7 +38,7 @@
 endif
ifeq ($(ARCH),nios)
-LOAD_ADDR = 0x01000000 -L $(gcclibdir)/m32 -T nios.lds
+LOAD_ADDR = 0x00800000 -L $(gcclibdir)/m32 -T nios.lds
 endif
ifeq ($(ARCH),m68k)
diff -Naurb u-boot-2004APR25/include/configs/DK1C20.h nios-jtag-gdb/include/configs/DK1C20.h
--- u-boot-2004APR25/include/configs/DK1C20.h	2004-04-20 19:11:20.000000000 -0400
+++ nios-jtag-gdb/include/configs/DK1C20.h	2004-04-25 16:13:08.000000000 -0400
@@ -471,6 +471,7 @@
    			 CFG_CMD_MII	| \
    			 CFG_CMD_PCI	| \
    			 CFG_CMD_PCMCIA | \
+				 CFG_CMD_REISER	| \
    			 CFG_CMD_SCSI	| \
    			 CFG_CMD_SPI	| \
    			 CFG_CMD_VFD	| \
diff -Naurb u-boot-2004APR25/include/nios-io.h nios-jtag-gdb/include/nios-io.h
--- u-boot-2004APR25/include/nios-io.h	2004-02-09 18:12:25.000000000 -0500
+++ nios-jtag-gdb/include/nios-io.h	2004-04-25 15:44:11.000000000 -0400
@@ -167,4 +167,17 @@
 #define NIOS_ASMI_IEOP		(1 << 9)	/* rx eop int ena */
 #define NIOS_ASMI_SSO		(1 << 10)	/* slave select enable */
+/*------------------------------------------------------------------------
+ * JTAG UART
+ *----------------------------------------------------------------------*/
+typedef volatile struct nios_jtag_t {
+	unsigned short	rxcntl;			/* Rx data/cntl reg */
+	unsigned short	txcntl;			/* Tx data/cntl reg */
+	unsigned short	errcntl;		/* Err dta/cntl reg */
+}nios_jtag_t;
+
+/* status register */
+#define NIOS_JTAG_TRDY		(1 << 8)	/* tx ready bit */
+#define NIOS_JTAG_RRDY		(1 << 8)	/* rx ready bit */
+
 #endif /* __NIOSIO_H__ */
diff -Naurb u-boot-2004APR25/lib_nios/board.c nios-jtag-gdb/lib_nios/board.c
--- u-boot-2004APR25/lib_nios/board.c	2004-02-23 18:54:52.000000000 -0500
+++ nios-jtag-gdb/lib_nios/board.c	2004-04-25 19:25:17.000000000 -0400
@@ -49,7 +49,6 @@
extern void malloc_bin_reloc (void);
 typedef int (init_fnc_t) (void);
-extern unsigned _vectors[];
/*
  * Begin and End of memory area for malloc(), and current "brk"
@@ -120,10 +119,6 @@
    gd = (gd_t *)CFG_GBL_DATA_OFFSET;
    memset( gd, 0, CFG_GBL_DATA_SIZE );
-	/* Copy exception vectors to the correct location.
-	 */
-	memcpy( (void *)CFG_VECT_BASE, _vectors, 256 );
-
    gd->bd = (bd_t *)(gd+1);	/* At end of global data */
    gd->baudrate = CONFIG_BAUDRATE;
    gd->cpu_clk = CONFIG_SYS_CLK_FREQ;
diff -Naurb u-boot-2004APR25/nios_config.mk nios-jtag-gdb/nios_config.mk
--- u-boot-2004APR25/nios_config.mk	2004-02-23 18:54:45.000000000 -0500
+++ nios-jtag-gdb/nios_config.mk	2004-04-25 19:24:02.000000000 -0400
@@ -22,4 +22,4 @@
 # MA 02111-1307 USA
 #
-PLATFORM_CPPFLAGS += -m32 -DCONFIG_NIOS -D__NIOS__ -ffixed-g7
+PLATFORM_CPPFLAGS += -m32 -DCONFIG_NIOS -D__NIOS__ -ffixed-g7 -gstabs

    