OK335xS U-boot GPIO control hacking

/****************************************************************************************
 *                           OK335xS U-boot GPIO control hacking
 * 声明：
 *     本文主要是跟踪U-boot中如何设置GPIO口电平。
 *
 *                                                  2015-9-26 晴 深圳 南山平山村 曾剑锋
 ***************************************************************************************/

cat board/forlinx/ok335x/evm.c
int board_init(void)
{
    int c = ;
    /* Configure the i2c0 pin mux */
    enable_i2c0_pin_mux();                                                                          

    i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);                                           

    board_id = GP_BOARD;
    profile = ;    /* profile 0 is internally considered as 1 */
    daughter_board_connected = ;                                                                   

    configure_evm_pin_mux(board_id, header.version, profile, daughter_board_connected); --+
                                                                                          |
    /**                                                                                   |
      * 1. 参考资料：                                                                     |
      *   AM335x ARM Cortex-A8 Microprocessors (MPUs) Technical Reference Manual (Rev. H) |
      *                                                                                   |
      * 2. ARM Cortex-A8 Memory Map                                                       |
      *             Table 2-2. L4_WKUP Peripheral Memory Map (continued)                  |
      * +-------------+---------------------+-------------------+------+----------------+ |
      * | Region Name | Start Address (hex) | End Address (hex) | Size | Description    | |
      * +-------------+---------------------+-------------------+------+----------------+ |
      * | GPIO0       | 0x44E0_7000         | 0x44E0_7FFF       | 4KB  | GPIO Registers | |
      * +-------------+---------------------+-------------------+------+----------------+ |
      *                                                                                   |
      * 3. GPIO Registers（4068 页）                                                      |
      *                 Table 25-5. GPIO REGISTERS                                        |
      * +--------+-------------------+---------------+-------------------+                |
      * | Offset | Acronym           | Register Name | Section           |                |
      * +--------+-------------------+---------------+-------------------+                |
      * | 134h   | GPIO_OE           |               | Section 25.4.1.16 |<-+             |
      * +--------+-------------------+---------------+-------------------+  |             |
      * | 190h   | GPIO_CLEARDATAOUT |               | Section 25.4.1.25 |  |<-+          |
      * +--------+-------------------+---------------+-------------------+  |  |          |
      * | 194h   | GPIO_SETDATAOUT   |               | Section 25.4.1.26 |  |  |<-+       |
      * +--------+-------------------+---------------+-------------------+  |  |  |       |
      */                                                                    |  |  |       |
    /* set gpio0_7 gpio0_12 gpio0_22 gpio0_23 output mode */                |  |  |       |
    __raw_writel(~((<<) | (<<) | (<<) |(<<)), 0x44E07134);-------+  |  |       |
    /* set gpio0_7 12 19 23 low */                                             |  |       |
    __raw_writel((<<) | (<<) | (<<), 0x44E07190);            ----------+  |       |
    /* set gpio0_22 high to height */                                             |       |
    __raw_writel( (<<) | (<<), 0x44E07194);                    -------------+       |
                                                                                          |
                                                                                          |
#ifndef CONFIG_SPL_BUILD                                                                  |
    board_evm_init();                                                                     |
#endif                                                                                    |
    gpmc_init();                                                                          |
                                                                                          |
    return ;                                                                             |
}               +-------------------------------------------------------------------------+
                V
void configure_evm_pin_mux(unsigned char dghtr_brd_id, char version[], unsigned short
        profile, unsigned int daughter_board_flag)
{
    if (dghtr_brd_id > BASE_BOARD)
        return;                                                                                     

    set_evm_pin_mux(am335x_evm_pin_mux[], profile,daughter_board_flag);
}                                 |
                                  V
static struct evm_pin_mux *am335x_evm_pin_mux[] = {
    general_purpose_evm_pin_mux,                      ----------------------+
};                                                                          |
                                                                            |
/*                                                                          |
 * Update the structure with the modules present in the general purpose     |
 * board and the profiles in which the modules are present.                 |
 * If the module is physically present but if it is not available           |
 * in any of the profile, then do not update it.                            |
 * For eg, nand is avialable only in the profiles 0 and 1, whereas          |
 * UART0  is available in all the profiles.                                 |
 */                                                                         |
static struct evm_pin_mux general_purpose_evm_pin_mux[] = {      <----------+
    {i2c1_pin_mux, PROFILE_ALL & ~PROFILE_2 & ~PROFILE_4, DEV_ON_BASEBOARD},                        

#ifdef CONFIG_NAND
    {nand_pin_mux, PROFILE_ALL & ~PROFILE_2 & ~PROFILE_3, DEV_ON_DGHTR_BRD},
#endif                                                                                              

#ifndef CONFIG_NO_ETH
    {mii1_pin_mux, PROFILE_ALL, DEV_ON_BASEBOARD},
#endif                                                                                              

#ifdef CONFIG_MMC
    {mmc0_pin_mux, PROFILE_ALL, DEV_ON_BASEBOARD},
#endif
    {backlight_pin_mux, PROFILE_ALL, DEV_ON_BASEBOARD},           -----+
    {maxttl_model_pin_mux, PROFILE_ALL, DEV_ON_BASEBOARD},             |
    {lcd_pin_mux, PROFILE_ALL, DEV_ON_BASEBOARD},                      |
    {uart0_pin_mux, PROFILE_ALL, DEV_ON_BASEBOARD},                    |
    {},                                                               |
};                                                                     |
                                                                       |
static struct module_pin_mux backlight_pin_mux[] = {              <----+
    {OFFSET(ecap0_in_pwm0_out), MODE() | PULLUP_EN | RXACTIVE}, /* GPIO0_7 */
    {OFFSET(uart1_ctsn), MODE() | PULLUDDIS | RXACTIVE},        /* GPIO0_ 12 */
    {-},
};