OSK5912 GPIO

Hi,

I AM WORKING ON OMAP5912 OSK.

I am writing a keyboard based gpio program to write a value '1' to the free gpio pin when a key was pressed.

For that I modified the gpio-switch.c program. I am using the up arrow key which is mapped to gpio7. By pressing this key I am able to write a value '1' to the gpio pin 23.

At the shell prompt I am able to see a logic '1' value at gpio pin 23 with the following message

value of pin # 23 = 1
up (GPIO 7) is now disconnected

But through the Cathode Ray Oscilloscope I am unable to observe the GPIO pin 23 value as ‘1’. There is no change in the Oscilloscope.

Here is my gpio-switch code

#define OMAP_GPIO_SW_POLL_DELAY 10

#define LED_GPIO 23

const struct omap_gpio_switch_config omap_left_switch = {
.name = "left",
.type = OMAP_GPIO_SWITCH_TYPE_CONNECTION, .gpio = 6,
.flags = OMAP_GPIO_SWITCH_FLAG_INVERTED, .key_code = KEY_LEFT
};

const struct omap_gpio_switch_config omap_enter_switch = {
.name = "enter",
.type = OMAP_GPIO_SWITCH_TYPE_CONNECTION, .gpio = 12,
.flags = OMAP_GPIO_SWITCH_FLAG_INVERTED, .key_code = KEY_ENTER
};

const struct omap_gpio_switch_config omap_up_switch = {
.name = "up",
.type = OMAP_GPIO_SWITCH_TYPE_CONNECTION, .gpio = 7,
.flags = OMAP_GPIO_SWITCH_FLAG_INVERTED, .key_code = KEY_UP
};

const struct omap_gpio_switch_config omap_down_switch = {
.name = "down",
.type = OMAP_GPIO_SWITCH_TYPE_CONNECTION, .gpio = 15,
.flags = OMAP_GPIO_SWITCH_FLAG_INVERTED, .key_code = KEY_DOWN
};

const struct omap_gpio_switch_config *omap_switches[] = {
&omap_left_switch,
&omap_enter_switch,
&omap_up_switch,
&omap_down_switch,
NULL /* Guard */
};

static void gpio_sw_handler(void *data)

{
    struct gpio_switch *sw = data;
    int state = gpio_sw_get_state(sw);

    if (sw->state == state)
          return;

    if (sw->type == OMAP_GPIO_SWITCH_TYPE_CONNECTION)
          kobject_uevent(&sw->pdev.dev.kobj, KOBJ_CHANGE,
                    &dev_attr_connection_switch.attr);
    else
          kobject_uevent(&sw->pdev.dev.kobj, KOBJ_CHANGE,
                    &dev_attr_cover_switch.attr);
    sw->state = state;
    input_report_key(&omap_sw_kp_dev, sw->key_code, state);
    
    /*** [START]: code for writing some value to GPIO 17 ***/

    if(sw->key_code==KEY_UP)
    {
          if(led_glow(sw))
              printk(KERN_ERR "led_glow:failed ");
    }    
    
    /*** [END]: code for writing some value to GPIO 17 ***/          

static int led_glow(struct gpio_switch *ctrlsw)

{
    /* requesting for LED_GPIO */
    if(omap_request_gpio(LED_GPIO)<0)
          return -1;
    
    /* setting LED_GPIO as output pin */
    omap_set_gpio_direction(LED_GPIO,0);

    /* writing to LED_GPIO the state of KEY_UP */
    omap_set_gpio_dataout(LED_GPIO,ctrlsw->state);

    /* printing the value of led_gpio pin */
    printk("value of pin # %d = %d\n",LED_GPIO,omap_get_gpio_datain(LED_GPIO));

    return 0;

}

please suggest where I had gone wrong.

With Regards
Azharuddin, India

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Generally it looks okay, but:

- omap_request_gpio() and omap_set_gpio_direction() should only be
used once, in the initialisation, not on every key event.

- omap_get_gpio_datain() should not be used with an output pin, only
for input pins. Otherwise the returned value may be false.

- I don't know why the pin 23 stays low on your oscilloscope, but it
may be a multiplexing not set up on the pin. You may need to call omap_cfg_reg() with some parameter, see if there is anything concerning this pin in include/asm-arm/arch-omap/mux.h and in the reference manual.

Regards