U-Boot porting (3) adds support for S3C2440

6. S3C2440 is an improved version of S3C2410. Their operations are basically similar, except for some minor differences in the settings of the system clock and the operation of the NAND Flash controller. . What I have to do next is to make a U-Boot binary code run on both S3C2410 and S3C2440.

        Although my board is also S3C2410, adding U-Boot exercises for S3C2440 can improve our abilities and lay the foundation for subsequent learning.

             The value of the GSTATUS1 register: 0x32410000 represents S3C2410, 0x32410002 represents S3C2440.

             S3C2410：FCLK＝200MHZ；S3C2440：FCLK＝400MHZ，UCLK＝48MHZ；

             After figuring it out, we can get started.

             First, define the following values ​​in front of board/100ask24x0/100ask24x0.c:

             The input clock of my development board is 12MHZ. If your development board clock is different from mine, you can calculate it according to the formula in the previous code, and then modify the system clock. This is in the macro CONFIG_SYS_CLK_FREQ in include/configs/100ask24x0.h definition.

          Next, use different macros to set the system clock, including S3C2410 and S3C2440.

7. When setting the serial port baud rate later, you need to obtain the system clock. This is in the second stage of U-Boot, that is, when the start_armboot function in lib_arm/board.c calls the serial_init function to initialize the serial port, it will call get_PCLK, get_HCLK, and get_PLLCLK. etc. function, which requires us to make corresponding modifications.

         First, you must add the following line to the switch of the board_init function to use the variable gd, because S3C2410 and S3C2440 are recognized and the machine type ID is set: gd->bd->bi_arch_number.                             

     Then add the following in the get_PLLCLK function:

        Since the frequency division coefficient setting methods are also different, get_HCLK and get_PCLK also need to be modified. Modify as follows:

  。。。。。。。。。。。

The above 3:6 should be changed to 6:3. I made a mistake here.

。。。。。。。。

3:6 changed to 6:3

8. The modification has been completed and can be compiled.

          (1)make    100ask24x0_config

          (2)make all

There were a lot of errors later, and I needed to be patient to search and correct them.