linux配置GPIO的方式

linux配置GPIO的方式

 

1.     Bootloader阶段的控制

\bootable\bootloader\lk\platform\msm8909\gpio.c

/* configure rx gpio */
       gpio_tlmm_config(21,3, GPIO_INPUT, GPIO_NO_PULL,
                            GPIO_8MA,GPIO_DISABLE);

这里的21是指GPIO_21，3表示function配置项，普通GPIO对应0，如下图：

图1

 

2.     Kernel阶段的控制

2.1  使用Pinctrl框架控制

 

(1)  设备树文件相关节点

sn7326_power_pin {
                qcom,pins = <&gp 3>;
                qcom,num-grp-pins = <1>;
                qcom,pin-func = <0>;
               
                label ="sn7326-power-pin";
                sn7326_power_active:sn7326_power_active {
                        drive-strength =<6>;
                        bias-pull-up;
                        output-high;
                       
                };
 
                sn7326_power_sleep:sn7326_power_sleep {
                        drive-strength =<2>;
                        bias-pull-down;
                        output-low;
                };
       };
 
sn@58 {
                     compatible= "sn,sn7326";
                     reg= <0x58>;                   
                       pinctrl-names ="active","sleep";
                       pinctrl-0 = <&sn7326_power_active>;
                       pinctrl-1 =<&sn7326_power_sleep>;
                     interrupt-parent= <&msm_gpio>;
                     interrupts= <98 0x02>;
                     …
          sn7326,pwr-en-gpio=<&msm_gpio 3 0x00>;//GPIO控制方式
              };

(2)  Pinctrl控制代码

static int sn7326_pinctrl_init(structsn7326_chip_data *data)
{
       struct i2c_client *client = data->client;
 
       data->pinctrl = devm_pinctrl_get(&client->dev);
       if (IS_ERR_OR_NULL(data->pinctrl)) {
                dev_err(&client->dev,"Failed to get pinctrl\n");
                returnPTR_ERR(data->pinctrl);
       }
 
       data->pin_active =
               pinctrl_lookup_state(data->pinctrl, "active");
       if (IS_ERR_OR_NULL(data->pin_active)) {
                dev_err(&client->dev,"Failed to look up default state\n");
                returnPTR_ERR(data->pin_active);
       }
 
       data->pin_sleep =
               pinctrl_lookup_state(data->pinctrl, "sleep");
       if (IS_ERR_OR_NULL(data->pin_sleep)) {
                dev_err(&client->dev,"Failed to look up sleep state\n");
                returnPTR_ERR(data->pin_sleep);
       }
 
       return 0;
}
 
 
ret =pinctrl_select_state(chip_data->pinctrl, chip_data->pin_active);
       if (ret) {
                dev_err(&client->dev,
                        "Can't selectpinctrl default state\n");
                goto free_pdata;
       }

这里的chip_data->pin_active指向sn7326_power_active。

(3)   

 

 

2.2  使用GPIO控制

(1)  设备树相关节点

sn@58 {
                     compatible= "sn,sn7326";
                     reg= <0x58>;                   
                     …
          sn7326,pwr-en-gpio=<&msm_gpio 3 0x00>;//GPIO控制方式
              };

(2)  代码控制

static int sn7326_kpd_parse_dt(structdevice *dev,struct sn7326_pdata *pdata)
{
       intret = 0;
      
       structdevice_node *np = dev->of_node;
       pdata->pwr_en_gpio= of_get_named_gpio_flags(np, "sn7326,pwr-en-gpio",0, NULL);
       if(gpio_is_valid(pdata->pwr_en_gpio)){
              ret= gpio_request(pdata->pwr_en_gpio, "sn7326_pwr_en");
              if(ret){
                     dev_err(dev,"%s: pwr-en gpio request failed.\n", __func__);
                     goto free_rst;
              }
              gpio_direction_output(pdata->pwr_en_gpio, 1);
       }
 
       pdata->irq_gpio= of_get_named_gpio_flags(np, "sn7326,interrupt-gpio",0, NULL);
       if(!gpio_is_valid(pdata->irq_gpio)) {
              gotofree_pwr_en;
       }
      
       returnret;
 
free_pwr_en:
       if(gpio_is_valid(pdata->pwr_en_gpio))
                     gpio_free(pdata->pwr_en_gpio);
       returnret;
}