Enable interrupt for GPIO 82 in DM365 running Linux

Hello,

You need to configure the pinmux as input and also configure the gpio pin as input.

Cheers,
--Prabhakar Lad

Yes, but I'm already doing that -- I can read the input correctly with function gpio_get_value(82), as I did in my tests. I just can't make it raise an interrupt when its state changes (which allow me to avoid polling the input every few milliseconds).

Excuse me if my post didn't make this clear.

Hello,

Just try the below code.

Cheers,
--Prabhakar Lad

#include <linux/module.h>
#include <linux/version.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/completion.h>
#include <mach/hardware.h>
#include <asm/gpio.h>


static int gpio_num;

DECLARE_COMPLETION(work);

static irqreturn_t handler (int irq, void * dev)
{
complete_all(&work);
return IRQ_HANDLED;
}

int init_module()
{
int status;
int irq;

init_completion(&work);

gpio_num = 82;

status = gpio_request(gpio_num, "gpio_test\n");
if (status < 0) {
printk("ERROR can not open GPIO %d\n", gpio_num);
return status;
}

gpio_export(gpio_num, true);

if(gpio_get_value(gpio_num) == 0)
printk("OFF. \n\tWaiting for the pin to be on..\n");
else
printk("ON. \n\tWaiting for the pin to be off..\n");

irq = gpio_to_irq(gpio_num);
status = request_irq(irq, handler, 0, "gpio_test", NULL);
if(status < 0) {
printk(KERN_ERR "error %d requesting GPIO IRQ %d\n", status, gpio_num);
return status;
}

set_irq_type(irq, IRQ_TYPE_EDGE_RISING);

wait_for_completion_interruptible(&work);

printk(".. done\n");

return 0;
}

void cleanup_module(void) {
free_irq(gpio_to_irq(gpio_num), NULL);
gpio_free(gpio_num);
}

MODULE_LICENSE("GPL");

Hello,

I just tried the test code (with changes, see bellow), but it failed with error -22 (invalid argument), exactly as happened before with my previous tests. It seems kernel refuses to register the IRQ.

The exact test sequence was:

root@camera /tmp# insmod testmod82.ko
insmod: can't insert 'testmod82.ko': Invalid argument
root@camera /tmp# insmod ./testmod82.ko
insmod: can't insert './testmod82.ko': Device or resource busy
root@camera /tmp# dmesg | tail
UBIFS: default compressor: lzo
UBIFS: reserved for root:  0 bytes (0 KiB)
vpfe-capture vpfe-capture: IPIPE Chained
vpfe-capture vpfe-capture: Resizer present
vpfe-capture vpfe-capture: input information not found for the subdev
ipipe_set_resizer, resizer - A enabled
OFF.
        Waiting for the pin to be on..
error -22 requesting GPIO IRQ 82
ERROR can not open GPIO 82

Also notice I made some changes to the original code: a typo in function irq_set_irq_type(), renamed init/cleanup_module, and changed the register "pinmux1" to connect GIO82 to the BGA pin C19 (where the GPIO is multiplexes with LCD_OE).  Follows the full code for reference:

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/types.h>
#include <linux/cdev.h>
#include <linux/delay.h>
#include <mach/hardware.h>
#include <linux/completion.h>
#include <asm/uaccess.h>
#include <asm/io.h>

static int gpio_num;

DECLARE_COMPLETION(work);


static void gpio_test_pinmux_config(void)
{
    static DEFINE_SPINLOCK(mux_spin_lock);
    unsigned long flags = 0;
    struct davinci_soc_info *soc_info = &davinci_soc_info;
    void __iomem *pinmux_base;
    void __iomem *pinmux1_addr;

    /* get pinmux address from soc_info */
    pinmux_base = ioremap(soc_info->pinmux_base, SZ_4K);
    pinmux1_addr = pinmux_base + 1 * sizeof(pinmux_base);

    spin_lock_irqsave(&mux_spin_lock, flags);
    /* GIO82: PINMUX1(BIT17) = 1 */
    __raw_writel((__raw_readl(pinmux1_addr) | (BIT(17))), pinmux1_addr);
    spin_unlock_irqrestore(&mux_spin_lock, flags);
}


static irqreturn_t handler (int irq, void * dev)
{
    complete_all(&work);
    return IRQ_HANDLED;
}

static int my_init_module(void)
{
    int status;
    int irq;

    init_completion(&work);

    gpio_num = 82;

    gpio_test_pinmux_config();
    status = gpio_request(gpio_num, "gpio_test\n");
    if (status < 0) {
        printk("ERROR can not open GPIO %d\n", gpio_num);
        return status;
    }

    gpio_export(gpio_num, true);

    if (gpio_get_value(gpio_num) == 0)
        printk("OFF. \n\tWaiting for the pin to be on..\n");
    else
        printk("ON. \n\tWaiting for the pin to be off..\n");

    irq = gpio_to_irq(gpio_num);
    status = request_irq(irq, handler, 0, "gpio_test", NULL);
    if(status < 0) {
        printk(KERN_ERR "error %d requesting GPIO IRQ %d\n", status, gpio_num);
        return status;
    }

    /* Was set_irq_type */
    irq_set_irq_type(irq, IRQ_TYPE_EDGE_RISING);
    wait_for_completion_interruptible(&work);

    printk(".. done\n");

    return 0;
}


static void my_cleanup_module(void) {
    free_irq(gpio_to_irq(gpio_num), NULL);
    gpio_free(gpio_num);
}

MODULE_LICENSE("GPL");
module_init(my_init_module);
module_exit(my_cleanup_module);

Hello,

can you post the output of the command 'cat /proc/interrupts'

can you try with request_irq(irq, handler, IRQF_SHARED, "gpio_test", NULL);

Cheers,
--Prabhakar Lad

Hello,

I haven't tried the shared interrupts before and was very hopeful when you brought this possibility up ... but it didn't worked too :(

root@camera /tmp# dmesg | tail
UBIFS: mounted UBI device 0, volume 0, name "ubifs"
UBIFS: file system size:   29966336 bytes (29264 KiB, 28 MiB, 236 LEBs)
UBIFS: journal size:       6348800 bytes (6200 KiB, 6 MiB, 50 LEBs)
UBIFS: media format:       w4/r0 (latest is w4/r0)
UBIFS: default compressor: lzo
UBIFS: reserved for root:  0 bytes (0 KiB)
vpfe-capture vpfe-capture: IPIPE Chained
vpfe-capture vpfe-capture: Resizer present
vpfe-capture vpfe-capture: input information not found for the subdev
ipipe_set_resizer, resizer - A enabled
root@camera /tmp# insmod ./testmod82shared.ko
insmod: can't insert './testmod82shared.ko': Invalid argument
root@camera /tmp# dmesg | tail
UBIFS: media format:       w4/r0 (latest is w4/r0)
UBIFS: default compressor: lzo
UBIFS: reserved for root:  0 bytes (0 KiB)
vpfe-capture vpfe-capture: IPIPE Chained
vpfe-capture vpfe-capture: Resizer present
vpfe-capture vpfe-capture: input information not found for the subdev
ipipe_set_resizer, resizer - A enabled
OFF.
        Waiting for the pin to be on..
error -22 requesting GPIO IRQ 82
root@camera /tmp# cat /proc/interrupts
           CPU0       
  0:      14022     AINTC  vpfe_capture0
  3:      14004     AINTC  dm365_h3a_af
  5:       7011     AINTC  Imp_Sdram_Irq
 16:          0     AINTC  edma
 17:          0     AINTC  edma_error
 32:      22827     AINTC  clockevent
 33:          1     AINTC  free-run counter
 39:       6985     AINTC  i2c_davinci
 41:         84     AINTC  serial
 52:          0     AINTC  eth0
 53:        709     AINTC  eth0
 54:        155     AINTC  eth0
 55:          0     AINTC  eth0
Err:          0
r

The /proc/interrupts with the non-shared version was

 root@camera /tmp# cat /proc/interrupts
           CPU0       
  0:     860131     AINTC  vpfe_capture0
  3:     860113     AINTC  dm365_h3a_af
  5:     430065     AINTC  Imp_Sdram_Irq
 16:          0     AINTC  edma
 17:          0     AINTC  edma_error
 32:    1330728     AINTC  clockevent
 33:         74     AINTC  free-run counter
 39:     303551     AINTC  i2c_davinci
 41:         84     AINTC  serial
 52:          0     AINTC  eth0
 53:      34138     AINTC  eth0
 54:        295     AINTC  eth0
 55:          0     AINTC  eth0
Err:          0

Hi,

Can you check the return value of gpio_to_irq() ? If it fails it returns negative number, try and print it.

Cheers,
--Prabhakar Lad

Interesting! I always though gpio_to_irq() as a static table kept somewhere in the BSP, but running this test I just got "gpio_to_irq(82) == -19". errno 19 is "No such device", which makes sense here.

Maybe the interrupt for this GPIO is disabled? I'm searching for registers which can enable it, but no success yet.

So, it seems my HW design is utterly broken and the alternative is polling the GPIO.

Anyway, thanks for the help!