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diff --git a/doc/README.nios b/doc/README.nios deleted file mode 100644 index 5628144..0000000 --- a/doc/README.nios +++ /dev/null @@ -1,366 +0,0 @@ - - U-Boot for Nios-32 - - Last Update: February 1, 2004 -==================================================================== - -This file contains information regarding U-Boot and the Altera -Nios CPU. For information regarding U-Boot and the Nios Development -Kits see: - - * Cyclone Edition (DK-1C20), see doc/README.dk1c20 - * Stratix Edition (DK-1S10), see doc/README.dk1s10 (TODO) - * Stratix Edition (DK-1S40), see doc/README.dk1s40 (TODO) - * Stratix Edition (DK-20K200), see doc/README.dk20k200 (TODO) - -For informations regarding Nios Development Kit hardware overview -and the NIOS CPU standard configuration of all known boards made by -Altera see: - - * Development Kit (DK) hardware overview, see doc/README.nios_DK - * NIOS CPU standard_32 at DK-1C20, see doc/README.dk1c20_std32 - * NIOS CPU standard_32 at DK-1S10, see doc/README.dk1s10_std32 - * NIOS CPU standard_32 at DK-1S40, see doc/README.dk1s40_std32 - * NIOS CPU standard_32 at DK-20K200, see doc/README.dk20k200_std32 - -For those interested in contributing ... see HELP WANTED below. - - -1. OVERVIEW ------------- - -U-Boot has been successfully tested on the Nios Cyclone development -board using both the 'safe' and 'standard 32' configurations with -Nios CPU revision 3.1 (CPU_ID = 0x3018). U-Boot can be used with -or without the GERMS monitor. The initial version of U-Boot for the -Cyclone development kit is about 60 Kbyte and will fit in a single -sector of on-board FLASH. Only the Nios 32-bit CPU is supported. - -1.1 GERMS Monitor ------------------- -If GERMS is just not enough, then U-Boot is a great antibiotic. -You will be very pleased with its high degree of configurability -and its rich feature set. - -A few of the most obvious limitations of GERMS are overcome by -using U-Boot (See 'Brain Damage'). Most notably, you can use -minicom or Hyperterminal (duh). - -1.2 Altera Source Code ------------------------ -The Nios port does NOT include ANY sources that Altera has the -copyright. This was a conscious decision ... not an accident. -The Altera license is not clear in terms of distributing Altera -sources (when altera silicon is not involved). This isn't really -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 ----------------------------------- - -2.1 Nios-specific Options/Settings ------------------------------------ -All configuration options/settings that are specific to Nios begin -with "CONFIG_NIOS_", "CONFIG_SYS_NIOS_", or "CONFIG_SYS_NIOS_CPU_". - -The configuration follows a two-stage process. In the first stage -the NIOS CPU core will defined like defined in Alteras SOPC Builder. -At this point we use the "CONFIG_SYS_NIOS_CPU_" defines exclusively. For -more informations about all the definitions you have to setup see -into current board configurations and doc/README.nios_CFG_NIOS_CPU. - -In second stage we bring the NIOS CPU configuration in relation to -U-Boot configuration options/settings. The following is a list of -currently defined Nios-specific options/parameters used inside of -U-Boot. If any options are related to Standard-32 Nios SDK -excalibur.h definitions, the related definition follows the -description). - -CONFIG_NIOS -- defined for all Nios-32 boards. - -CONFIG_SYS_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). - -CONFIG_SYS_NIOS_FIXEDBAUD -- defined if the console UART PTF fixed_baud - parameter is set to '1'. - -CONFIG_SYS_NIOS_MULT_HW -- use full hardware multiply (not yet implemented). - -CONFIG_SYS_NIOS_MULT_MSTEP -- use hardware assisted multiply using the - MSTEP instruction (not yet implemented). - -CONFIG_SYS_NIOS_TMRBASE -- the base address of the timer used to support - xxx_timer routines (e.g. set_timer(), get_timer(), etc.). - (standard-32: nasys_timer_1 resp. na_lo_priority_timer2_base). - -CONFIG_SYS_NIOS_TMRIRQ -- the interrupt request (vector number) assigned to - the timer. (standard-32: nasys_timer_1_irq resp. - na_low_priority_timer2_irq). - -CONFIG_SYS_NIOS_TMRMS -- the period of the timer in milliseconds. - -CONFIG_SYS_NIOS_TMRCNT -- the preloadable counter value for the timer if it has - no fixed period. - -CONFIG_SYS_NIOS_ASMIBASE -- the base address of the ASMI peripheral. - (standard-32: na_asmi_base). - -CONFIG_SYS_NIOS_SPIBASE -- the base address of the SPI master (!) peripheral. - (nasys_spi_0) - -CONFIG_SYS_NIOS_SPIBITS -- the amount of configured SPI data bits in PTF. - This value can be 8 or 16 only! (PTF: databits) - - -2.2 Differences in U-Boot Options/Settings -------------------------------------------- -Some 'standard' U-Boot options/settings are treated differently in -the Nios port. These are described below. - -CONFIG_SYS_GBL_DATA_OFFSET -- in the Nios port, this is the offset of the - global data structure in the Nios memory space. More simply, - the address of global data. - - -3. ASSEMBLY CODING -------------------- - -In browsing the assembly source files, you may notice the absence -of the 'magic macros' (e.g. MOVIA, MOVIP, ADDIP etc.). This is -deliberate. The documentation for the magic macros is scant and -it is hard to find ... it does not appear in the Nios programmer's -manual, nor does it appear in the assembler manual. Regardless, -the macros actually do very little to improve readability anyway. - -With this in mind, all assembler modules use only instructions that -appear in the Nios programmer's manual OR are directly supported -by the nios-elf toolchain. For example, the 'dec %rB' instruction -is an alias for 'subi %rB,1' that is supported by the assembler -but does not appear in the programmer's manual. - - -4. BOOT PROCESS ---------------- - -4.1 Boot process over GERMS ---------------------------- -When the NIOS CPU catch a reset signal it will begin to be running -code from CONFIG_SYS_NIOS_CPU_RST_VECT. Normally at this place it will -find the GERMS monitor. That's the case for the generic NIOS CPU -configuration "standard_32". When the GERMS monitor starts running, -it performs important system initializations and then looks for -executable code in flash, using the following steps: - - 1. Examining the two bytes at CONFIG_SYS_NIOS_CPU_FLASH_BASE + 0x04000C. - 2. Examining the button 0 on the PIO CONFIG_SYS_NIOS_CPU_BUTTON_PIO. - 3. If the button is not pressed and the two bytes contain 'N' - and 'i', the monitor executes a CALL to location - CONFIG_SYS_NIOS_CPU_FLASH_BASE + 0x040000. - 4. If the code is not executed in step 3 or the code returns, - then prints an 8-digit version number to STDOUT and waits for - user commands from STDIN. - -In normal case, for "standard_32", STDIN and STDOUT are the first -serial port. - -4.2 Return to GERMS command line --------------------------------- -During the boot process, the GERMS monitor checks for the existence -of application software in flash memory. If found, the processor -immediately executes the code. To return program execution to the -GERMS monitor (that is, avoid running code stored in flash memory): - - 1. Hold down CONFIG_SYS_NIOS_CPU_BUTTON_PIO, button number 0. - 2. Press then release the CPU reset button. - 3. Release CONFIG_SYS_NIOS_CPU_BUTTON_PIO, button number 0. - - -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 arch/nios/cpu - (gdb) directory arch/nios/lib - (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. - -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. - -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. -In addition, many of the standard utilities are very dated as well. -If you try to download and build the lastest version of grep for -example, you'll quickly realize that a native gcc is not available -(the next topic) which leads to U-Boot build problems (following -topic). - -The solution ... well, you can wait for Altera ... or build as -set of tools for linux. - -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 -environment -- forget it! A native (cygwin) gcc is not distributed, -and the old version of cygwin makes locating one challenging. - -The solution ... same as above. Just download the gcc source from -Altera and build up a set of cross tools for your favorite linux -distro. Anybody who wants to use an already precompiled NIOS cross -toolchain can it found in the CDK4NIOS project hosted by Source -Forge at http://cdk4nios.sourceforge.net. - -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 -native gcc, this (obviously) causes problems. - -For developers using the Altera cygwin tools you can remove the -'tools' directory from SUBDIRS in the top-level Makefile. You will -also have to edit common/Makefile: - -Replace: -env_embedded.o: env_embedded.c ../tools/envcrc - $(CC) $(AFLAGS) -Wa,--no-warn \ - -DENV_CRC=$(shell ../tools/envcrc) \ - -c -o $@ env_embedded.c - -With: -env_embedded.o: env_embedded.c - $(CC) $(AFLAGS) -Wa,--no-warn \ - -DENV_CRC=0 \ - -c -o $@ env_embedded.c - -BTW, thats a 'zero' ... not the letter 'O'. And not that the -"../tools/envcrc" dependency is removed. - - -7. HELP WANTED ---------------- - -There are plenty of areas where help is needed. Here's are some ideas -for those interested in contributing: - --CompactFlash. Port & test CF/FAT. - --Bedbug. Develop bedbug for Nios ... or at least provide a disassemble - command. - --Add boot support for ucLinux (niosnommu). - --Implement (don't copy Altera code) the __mulxx routines using the - MSTEP and MUL instructions (e.g. CONFIG_SYS_NIOS_MULT_HW and CONFIG_SYS_NIOS_MULT_MSTEP). - - -Regards, - ---Scott -<smcnutt@psyent.com> - ---Stephan -<linz@li-pro.net> |