MIPS平台suspend/resume时GPIO状态控制

这两天在调一款触摸屏的驱动，在调试过程中发现，在休眠的时候，所用到的几个GPIO引脚的状态会自动变为低电平，在唤醒后又会回到高电平。但是在代码里并没有显式地去拉低/拉高。很明显这不是我们想要的，如果这样的话，GPIO的状态都无法自己控制，还怎么调呢？

         问了下板子的FAE，GPIO的状态在休眠时，是预定义的。代码在

arch/mips/jz4770/boards/gps1/gps1-pm.c

其中gps1是板子类型

29 int gpio_sleep_state_table[][2] = {
30     /* GPIO Group - A */
31     {32 * 0 +  0,   GSS_INPUT_NOPULL}, /* NC */
32     {32 * 0 +  1,   GSS_INPUT_PULL  }, /* ACC_INT2 input pull*/
33     {32 * 0 +  2,   GSS_IGNORE      }, /* FVDD_EN */
34     {32 * 0 +  3,   GSS_INPUT_NOPULL}, /* SCLK */
35     {32 * 0 +  4,   GSS_INPUT_NOPULL}, /* NC */
36     {32 * 0 +  5,   GSS_INPUT_NOPULL}, /* NC */
37     {32 * 0 +  6,   GSS_INPUT_NOPULL}, /* PA6/SDATA */
38     {32 * 0 +  7,   GSS_INPUT_NOPULL}, /* NC */
39     {32 * 0 +  8,   GSS_INPUT_NOPULL}, /* NC */
40     {32 * 0 +  9,   GSS_INPUT_PULL  }, /* ACC_INT1 input pull*/
41     {32 * 0 + 10,   GSS_INPUT_NOPULL}, /* NC */
42     {32 * 0 + 11,   GSS_INPUT_NOPULL}, /* NC */
43     {32 * 0 + 12,   GSS_INPUT_NOPULL}, /* NC */
44     {32 * 0 + 13,   GSS_INPUT_NOPULL}, /* NC */
45     {32 * 0 + 14,   GSS_INPUT_NOPULL}, /* NC */
46     {32 * 0 + 15,   GSS_INPUT_NOPULL}, /* NC */
47     {32 * 0 + 16,   GSS_INPUT_NOPULL}, /* NC */

....

这里进行了所有GPIO在休眠时的状态的预定义。

在arch/mips/jz4770/common/pm.c中

509 int __init gpio_sleep_state_check(void)
510 {
511     unsigned int i,state,group,index;
512     unsigned int panic_flags[6] = {0,};
513
514     for(i = 0; i < GPIO_PORT_NUM; i++)
515         gpio_intput_pull[i] = 0xffffffff;
516
517     for(i = 0; gpio_sleep_state_table[i][1] != GSS_TABLET_END;i++) {
518         group = gpio_sleep_state_table[i][0] / 32;
519         index = gpio_sleep_state_table[i][0] % 32;
520         state = gpio_sleep_state_table[i][1];
521
522         gpio_intput_pull[group] = gpio_intput_pull[group] & ~(1 << index);
523         if(panic_flags[group] & (1 << index)) {
524             printk("\nwarning : (%d line) same gpio already set before this line!\n",i);
525             printk("\nwarning : (%d line) same gpio already set before this line!\n",i);
526             printk("\nwarning : (%d line) same gpio already set before this line!\n",i);
527             printk("\nwarning : (%d line) same gpio already set before this line!\n",i);
528             printk("\nwarning : (%d line) same gpio already set before this line!\n",i);
529             printk("\nwarning : (%d line) same gpio already set before this line!\n",i);
530             printk("\nwarning : (%d line) same gpio already set before this line!\n",i);
531             panic("gpio_sleep_state_table has iterant gpio set , system halt\n");
532             while(1);
533         } else {
534             panic_flags[group] |= 1 << index;
535         }
536

           <span style="color:#ff0000;"> //这里对预设的各种状态进行处理</span>
537         switch(state) {
538             case GSS_OUTPUT_HIGH:gpio_output_high[group] |= 1 << index;break;
539             case GSS_OUTPUT_LOW:gpio_output_low[group] |= 1 << index;break;
540             case GSS_INPUT_PULL:gpio_intput_pull[group] |= 1 << index;break;
541             case GSS_INPUT_NOPULL:gpio_intput_nopull[group] |= 1 << index;break;
542         }
543     }
544
545     for(i = 0; i < GPIO_PORT_NUM; i++) {
546         printk("%8x\t\t", gpio_output_low[i]);
547         printk("%8x\t\t", gpio_output_high[i]);
548         printk("%8x\t\t", gpio_intput_pull[i]);
549         printk("%8x\n", gpio_intput_nopull[i]);
550     }
551
552     return 0;
553 }

在进行suspend的时候，跑到这里对预设的GPIO进行设置

 98 void jzsoc_do_sleep(unsigned long *ptr)
 99 {
100     unsigned char i;
101
102     /* Print messages of GPIO registers for debug */
103     print_gpio();
104     /* Save GPIO registers */
105
106     for(i = 0; i < GPIO_PORT_NUM; i++) {
107         *ptr++ = REG_GPIO_PXINT(i);
108         *ptr++ = REG_GPIO_PXMSK(i);
109         *ptr++ = REG_GPIO_PXPAT1(i);
110         *ptr++ = REG_GPIO_PXPAT0(i);
111         *ptr++ = REG_GPIO_PXPEN(i);
112     }
113
114     for(i = 0; i < GPIO_PORT_NUM; i++) {
115         __gpio_group_as_output_low(i, gpio_output_low[i]);
116         __gpio_group_as_output_high(i, gpio_output_high[i]);
117         __gpio_group_as_input_pull(i, gpio_intput_pull[i]);
118         __gpio_group_as_input_nopull(i, gpio_intput_nopull[i]);
119     }

如果我们想需要手动进行管理需要的GPIO口，只需要将预设的状态改为GSS_IGNORE即可。

原文链接http://blog.csdn.net/laojing123/article/details/8131801