main_edit2.c

ARM-LINUX,基于S3c2410处理器的开发板实验源代码

                /*call arm920_setup in arch/s3c2410/mmu.c:
                    1. invalidate I,D caches
                    2. drain write buffer
                    3. invalidate I,D TLBs
                    4. load page table pointer(has been initialized at mmm_mapping_linear upside)
                    5. set MMU control registers:
                        a. base location of exception = 0 (exception vectors' start address is 0x00000000)
                        b. RS=0b00 (RS is not used as AP=0b11 which means all access types permitted 
                           in both supervisor and user mode)
                        c. set little-endian
                        d. mmu enable
                    */
    putstr("Succeed memory mapping.\r\n");

    /* initialize the heap area*/
    ret = heap_init();  /*lib/heap.c*/
i                        /*heap is a memory from which the function mmalloc require a memory block
                          it calls mmalloc_init in lib/heap.c to initialize the heap
                        */

    if (ret) {
        putstr("Failed initailizing heap region\r\n");
        error();
    }

    ret = mtd_dev_init();   /*drivers/mtd/mtdcore.c*/
                            /*it calls the functions mtd_init at drivers/mtd/maps/s3c2410_flash.c:
                                calls smc_init at the same file:
                                    a. mmalloc memory for strcut mymtd
                                    b. initialize (struct nand_chip *)(&mymtd[1]) for NAND FLASH
                                    c. call smc_insert at the same file:
                                        call the functions smc_scan at drivers/mtd/nand/smc_core.c:
                                            read the ID of NAND FLASH, compare it with the pre-defined                                    
                                            infomation of some usual types of NAND FLASH, and then
                                              set the NAND FLASH's data struct (struct nand_chip *)(&mymtd[1]).
                            */
    init_priv_data();   /*lib/priv_data/rw.c*/
                        /*there are two sets of vivi's parameters, one are the default parameters and the other are the saved parameters.
                          init_priv_data load the default parameters on the memory, and then load the saved parameters and overwrite                  the corespointing part of the default parameters if the saved parameters is validate. The saved parameters were
                          stored at the param partion of nand flash.
                        1. get_default_data(lib/priv_data/rw.c):
                            a. get_default_param_tlb, defined at struct default_vivi_parameters at arch/s3c2410/smdk.c
                            b. get_default_linux_cmd, copy linux command "char linux_cmd[] = "noinitrd root=/dev/mtdblock/0 
                               init=/linuxrc console=ttyS0" "(arch/s3c2410/smdk.c)
                            c. get_default_mtd_partition, defined at struct default_mtd_partitions at arch/s3c2410/smdk.c
                        2. load_saved_priv_data(lib/priv_data/rw.c):
                            a. read_saved_priv_data_blk(at the same file), read the saved vivi parameters from the param part of 
                              nand flash to DRAM_BASE
                            b. copy the saved tlb parameters from DRAM_BASE to overwrite what 1.a stores
                            c. copy the saved linux command from DRAM_BASE to overwrite what 1.b stores
                            d. copy the saved part parameters from DRAM_BASE to overwrite what 1.c stores
                        */
    
    misc(); /*arch/s3c2410/smdk.c*/
            /*call the function add_command(&cpu_cmd) defined at lib/command.c, to add the cpu command to the command chain
              this command is used to change the cpu's clock
            */  

    init_builtin_cmds();    /*lib/command.c*/
                            /*1. add_command(&bon_cmd)
                              2. add_command(&reset_cmd)
                              3. add_command(&param_cmd)
                              4. add_command(&part_cmd)
                              5. add_command(&mem_cmd)
                              6. add_command(&load_cmd)
                              7. add_command(&go_cmd)
                              8. add_command(&dump_cmd)
                              9. add_command(&call_cmd)
                              10.add_command(&boot_cmd)
                              11.add_command(&help_cmd)
                            */

    boot_or_vivi(); /*call vivi_shell() or run_autoboot.
                      1. run_autoboot:
                        exec_string("boot") (lib/command.c):
                            parse the sting "boot", and then call the function execcmd:
                                use the execcmd's parameter to find the boot_cmd's function and executive it:
                                    the boot_cmd was defined at lib/boot_kernel.c(see follow):
                                    user_command_t boot_cmd = {
                                        "boot",
                                        command_boot,
                                        NULL,
                                        "boot [{cmds}] \t\t\t-- Booting linux kernel"
                                        };
                                    so, we call the function command_boot(lib/boot_kernel.c):       
                                        a. media_type = get_param_value("media_type", &ret) 
                                          (lib/priv_data/param.c), media_type=3
                                        b. kernel_part = get_mtd_partition("kernel")
                                          (lib/priv_data/mtdpart.c), see also arch/s3c2410/smdk.c
                                            name:       "kernel",
                                            offset:     0x00030000,
                                            size:       0x00100000,
                                            flag:       0
                                        c. boot_kernel(from, size, media_type) (lib/boot_kernel.c):
                                            i. copy the kernel image from the kernel partion on nand
                                              flash to ram(boot_mem_base + LINUX_KERNEL_OFFSET,
                                              0x30008000)using the copy_kernel_img.
                                            ii.setup_linux_param, set the linux parameters at
                                              boot_mem_base + LINUX_PARAM_OFFSET(0x30000100), 
                                              these parameters were stored as a struct param_struct,
                                              which contains the command line parameter.
                                            iii.call_linux(0, mach_type, to) 
                                              (boot_mem_base + LINUX_KERNEL_OFFSET=0x30008000)
                                                (1). cache_clean_invalidate
                                                (2). tlb_invalidate
                                                (3). use the inline asm to jump to linux kernel:
                                                    define the p15 corprocessor:
                                                    zero PID
                                                    invalidate I,D caches
                                                    drain write buffer
                                                    invalidate I,D TLBs
                                                    get control register
                                                    disable MMU
                                                    write control register
                                                    set the PC register as the kernel address:
                                                    mov pc, r2
                    2. vivi_shell:
                        call the function serial_term at drivers/serial/term.c:
                            a. printk("%s> ", prompt), display the string "vivi>"
                            b. getcmd(cmd_buf, MAX_CMDBUF_SIZE) at drivers/serial/getcmd.c, wait for the command send
                               from serial port by user
                            c. exec_string(cmd_buf) at lib/command.c:
                                parseargs
                                execcmd
                    */
/*******************************************************************************************
Now, the DRAM is seperated to these parts;
+-----------------------------------------------    + 0x33ff_ffff = 0x3000_0000+64M-1
+                       +
+                       +
+       1M  VIVI        +
+                       +
+                       +
+-----------------------------------------------+ 0x33f0_0000 = VIVI_RAM_BASE
+                       +
+                       +
+       1M  HEAP        +
+                       +
+                       +
+-----------------------------------------------+ 0x33e0_0000 = HEAP_BASE
+       16k MMU_TABLE   +
+-----------------------------------------------+ 0x33df_c000 = MMU_TABLE_BASE (used at the stage2 of bootloader)
+       16k LINUX_CMD   +
+                       + LINUX_CMD_OFFSET = 16 k
+       16k PARAMETER_TLB       +
+                       + PARAMETER_TLB_OFFSET = 16k
+       16k PARAMETER_PART  +
+-----------------------------------------------+ 0x33df_0000 = VIVI_PRIV_RAM_BASE (PARAMETER_PART_OFFSET = 0)
+                       +
+       32k STACK       + 
+                       +
+-----------------------------------------------+ 0x33de_8000 = STACK_BASE
+           .           +
+           .           +
+           .           +
+           .           +
+           .           +
+           .           +
+-----------------------------------------------+
+                       +
+                       +
+       1M  LINUX KERNEL        +
+                       +
+                       +
+-----------------------------------------------+ 0x3000_8000 = the kernel image is placed begin this address
+                       +
+           LINUX PAREMETER + 
+-----------------------------------------------+ LINUX_PARAM_OFFSET = 0x100
+-----------------------------------------------+ 0x3000_0000 = RAM_BASE

*******************************************************************************************/

    return 0;
}