CODEWITHSUNDEEP
linux-kernellinux-device-driverdevice-tree
Raulp
Raulp

Reputation: 8136

correct way to get the gpio number from the device tree

Is this

of_get_named_gpio(child, "gpio-name", 0);

a correct way to get the GPIO number? Where the corresponding device tree is as below: 

gpio-name = <&gpio0 21 0>;

I get this error:

probe of failed with error -2

What does error code -2 represents? Is this a device tree parsing error?

Upvotes: 2

Views: 7620

Answers (1)

Prasanna Kulkarni
Prasanna Kulkarni

Reputation: 11

This snap-shot of the code shows how to get/set the particular GPIO. it is a tested code. 

     struct device_node *np = client->dev.of_node;
     int gpio;
     u8 buf[MAX_I2C_DATA_LEN];   
     int ret, tries = 0;

     if (!np)
             return -ENODEV;            

     gpio = of_get_named_gpio(np, "**gpio-name-used-in-dts-file**", 0); 
     if (!gpio_is_valid(gpio))
             return -ENODEV;            

     ret = gpio_request(gpio, "egalax_irq");  
     if (ret < 0) {            
          dev_err(&client->dev,
         "request gpio failed, cannot wake up controller: %d\n",ret);
             return ret;
     }   

     gpio_direction_output(gpio, 1); 
     ret = gpio_get_value(gpio);

     ""ret"" Will have gpio value.

Upvotes: 1

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