topic libgpiod with Linux gpio-imx-rpmsg.c driver in i.MX Processors

libgpiod with Linux gpio-imx-rpmsg.c driver

kef2 — Fri, 08 Oct 2021 16:35:58 GMT

Is there anyone familiar with gpio-imx-rpmsg.c driver, { .compatible = "fsl,imx-rpmsg-gpio" }? Perhaps not, since it is demonstrated only with i.MX7ULP, forums search doesn't give a lot of hits.

Is that driver supposed to work with libgpiod? I'm using kernel 5.4.x. gpioget shell command works, gpioset command works as well , gpiomon doesn't work:

# gpiomon gpiochip8 16 gpiomon: error waiting for events: No such device

As well sysfs doesn't list "edge" file here

# echo 272 > /sys/class/gpio/export # ls /sys/class/gpio/gpio272 active_low device power suppliers value consumers direction subsystem uevent

"edge" is present with i.MX7D native GPIO driver:

# echo 176 > /sys/class/gpio/export root@rcserv:~# ls /sys/class/gpio/gpio176 active_low device edge subsystem uevent consumers direction power suppliers value

Thanks

Edward

Re: libgpiod with Linux gpio-imx-rpmsg.c driver

kef2 — Fri, 08 Oct 2021 21:40:06 GMT

to_irq is missing in the driver. With copy paste from other driver gpiomon seems waiting, proper RPMSG request seems being sent along with launch of gpiomon. Need to fix M4 part to make both parts working:

diff --git a/drivers/gpio/gpio-imx-rpmsg.c b/drivers/gpio/gpio-imx-rpmsg.c index 418455f..4abbabb 100644 --- a/drivers/gpio/gpio-imx-rpmsg.c +++ b/drivers/gpio/gpio-imx-rpmsg.c @@ -310,6 +310,13 @@ static void imx_rpmsg_mask_irq(struct irq_data *d) /* No need to implement the callback */ } +static int imx_rpmsg_gpio_to_irq(struct gpio_chip *gc, unsigned offset) +{ + struct imx_rpmsg_gpio_port *port = gpiochip_get_data(gc); + + return irq_find_mapping(port->domain, offset); +} + static struct irq_chip imx_rpmsg_irq_chip = { .irq_mask = imx_rpmsg_mask_irq, .irq_unmask = imx_rpmsg_unmask_irq, @@ -337,6 +344,7 @@ static int imx_rpmsg_gpio_probe(struct platform_device *pdev) gc = &port->gc; gc->of_node = np; gc->parent = dev; + gc->to_irq = imx_rpmsg_gpio_to_irq; gc->label = "imx-rpmsg-gpio"; gc->ngpio = IMX_RPMSG_GPIO_PER_PORT; gc->base = of_alias_get_id(np, "gpio") * IMX_RPMSG_GPIO_PER_PORT;

Edit: as well "edge" file is present using GPIO sysfs.

Edward

Re: libgpiod with Linux gpio-imx-rpmsg.c driver

igorpadykov — Sun, 10 Oct 2021 09:19:38 GMT

Hi Edward

thanks for sharing patch, you are right by default gpio-imx-rpmsg driver is not supposed to work with libgpiod.

Best regards
igor

Re: libgpiod with Linux gpio-imx-rpmsg.c driver

kef2 — Fri, 12 Nov 2021 16:55:45 GMT

Hi Igor,

Indeed it doesn't matter, libgpiod or sysfs+poll(). RPMSG GPIO interrupts are documented ... but not implemented.

gpio-imx-rpmsg.c\gpio\drivers - linux-imx - i.MX Linux kernel (codeaurora.org)

Here's RPMSG callback with TBD:

static int gpio_rpmsg_cb(struct rpmsg_device *rpdev, void *data, int len, void *priv, u32 src) { struct gpio_rpmsg_data *msg = (struct gpio_rpmsg_data *)data; if (msg->header.type == GPIO_RPMSG_REPLY) { gpio_rpmsg.reply_msg = msg; complete(&gpio_rpmsg.cmd_complete); } else if (msg->header.type == GPIO_RPMSG_NOTIFY) { gpio_rpmsg.notify_msg = msg; /* TBD for interrupt handler */ } else dev_err(&gpio_rpmsg.rpdev->dev, "wrong command type!\n"); return 0; }

Replacing TBD with generic_handle_irq() with right arguments make interrupts working. Both libgpiod and sysfs.

Perhaps complete version of driver is lost somewhere? It's of course good to write documentation first and then implement according to documentation. But, hm, I'd prefer both complete and working :-). As I understand iMX7ULP EVK doesn't use RPMSG GPIO interrupts, buttons are used by RPMSG keyboard driver.

Regards

Edward

Re: libgpiod with Linux gpio-imx-rpmsg.c driver

nxf77080 — Fri, 12 Nov 2021 16:18:03 GMT

"Replacing TBD with generic_handle_irq() with right arguments make interrupts working. Both libgpiod and sysfs." What are the right arguments if I may ask?

Re: libgpiod with Linux gpio-imx-rpmsg.c driver

nxf77080 — Fri, 12 Nov 2021 16:21:14 GMT

"Replacing TBD with generic_handle_irq() with right arguments make interrupts working. Both libgpiod and sysfs." What are the right arguments? Thanks in advance.

Re: libgpiod with Linux gpio-imx-rpmsg.c driver

nxf77080 — Fri, 12 Nov 2021 16:22:22 GMT

Oops...did not see the patch. Thanks so much!!!

Re: libgpiod with Linux gpio-imx-rpmsg.c driver

kef2 — Fri, 12 Nov 2021 17:06:43 GMT

Hi, @nxf77080

that patch above was only to fix missing interrupt `edge` file. See attached whole driver source file after additional mods. Interrupts and IO seem working well. Would be nice to get rid of static gpio_rpmsg struct, I've no time for it

Regards,

Edward

Re: libgpiod with Linux gpio-imx-rpmsg.c driver

nxf77080 — Sun, 21 Nov 2021 12:50:32 GMT

Hi kef2, Where is the corresponding M4 FreeRTOS application? Thanks in advance. Best Regards, Rob

Re: libgpiod with Linux gpio-imx-rpmsg.c driver

kef2 — Sun, 21 Nov 2021 19:18:55 GMT

As a NXP employee you should know much better than me where to get examples for corresponding Cortex-M code. It was quite hard to get answer: get MCUXpresso SDK for i.MX7ULP.

Regards

Edward

Re: libgpiod with Linux gpio-imx-rpmsg.c driver

nxf77080 — Sun, 21 Nov 2021 19:24:15 GMT

Yep, have the SDK. Thought maybe you had made mods to the M4 side.

Thanks

Re: libgpiod with Linux gpio-imx-rpmsg.c driver

kef2 — Mon, 22 Nov 2021 09:26:38 GMT

Of course I had to shave tons of codes unsuitable for i.MX7D code, I can't share it.

GPIO interrupts already are implemented in SDK. Cortex-M GPIO interrupt handler includes SRTM_IoService_NotifyInputEvent() call. This call is used to signal GPIO interrupt over RPMSG. This works well with edge sensitive interrupts. Level sensitive interrupts should limit reporting rate, else RPMSG queue may overflow. It should be implemented on Cortex-M.

Edward

Re: libgpiod with Linux gpio-imx-rpmsg.c driver

nxf77080 — Mon, 22 Nov 2021 13:27:22 GMT

Thanks. I figured some rate limiting would have to be employed on the M4 side for level sensitive interrupts.

Best Regards,

Rob