<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div></div><div><br></div><div><br>On Jan 23, 2017, at 10:56 PM, Rajasekhar Pulluru <<a href="mailto:pullururajasekhar@gmail.com">pullururajasekhar@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr">Hi Anish,<div><br></div><div>My intention is just to detect interrupt in the user space and read the device id without using udev.</div><div><br></div><div>I don't want to create a new driver in kernel (assume I can't modify linux kernel sources), which is the first reason to go for uio generic platform driver.</div><div><br></div><div>If I register a gpio interrupt (level triggered) using a kernel module, I can get the interrupt detected </div></div></div></blockquote><div><br></div>Which means you are able to do insmod, so you can very well write a kernel module and send some event to user space.<br><blockquote type="cite"><div><div dir="ltr"><div>when device is inserted/removed. But I would like to detect device presence completely from user space without modifying linux kernel.</div><div><br></div><div>Thanks & Regards,</div><div>Rajasekhar</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jan 24, 2017 at 11:56 AM, anish singh <span dir="ltr"><<a href="mailto:anish198519851985@gmail.com" target="_blank">anish198519851985@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="h5">On Mon, Jan 23, 2017 at 7:46 AM, Rajasekhar Pulluru <span dir="ltr"><<a href="mailto:pullururajasekhar@gmail.com" target="_blank">pullururajasekhar@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Hi,</div><div><br></div><div>I have a query on device tree pertaining to modelling a gpio pin as an interrupt source. </div><div>I have searched mailing list archives and kernel documentation before posting this and couldn't get any direct solution.</div><div>(My understanding is limited and hence posting the query below:)</div><div><br></div><div>My SOC has a gpio controller and uart both sharing same interrupt line as specified below. </div><div><br></div><div><span class="m_-656488108402783319m_-7514866219543690092gmail-Apple-tab-span" style="white-space:pre-wrap"> </span>interrupt-parent = <&gic>;</div><div><br></div><div> mygpio: gpio@0x19008000 {</div><div> compatible = "mysoc,mygpio-controller,gc";</div><div> #address-cells = <1>;</div><div> #size-cells = <1>;</div><div> #gpio-cells = <2>;</div><div> reg = gpio: <0x19008000 0x50>;</div><div> ngpios = <12>;</div><div> pin-offset = <4>;</div><div> pin-base = <4>;</div><div> irq-base = <256>; /* sw irq base for irq handlers */</div><div> gpio-controller;</div><div> interrupt-controller;</div><div> interrupts = <GIC_SPI 91 IRQ_TYPE_LEVEL_HIGH>;</div><div> };</div><div><br></div><div> uart0: serial@0x19000300 {</div><div> compatible = "snps,dw-apb-uart";</div><div> reg = <0x19000300 0x100>;</div><div> interrupts = <GIC_SPI 91 IRQ_TYPE_LEVEL_HIGH>;</div><div> clock-frequency = <62500000>;</div><div> };</div><div><br></div><div>gpio pin 0 of mygpio is used as an interrupt source for detecting the presence of external pluggable device (that is not driven by kernel). </div><div>And I intend to detect the presence of the pluggable device from user space by means of generic uio platform driver using below device</div></div></blockquote><div><br></div></div></div><div>What do you intend to achieve by detecting device in userspace?<br></div><div>You can directly get notification using udev notification.<br><br></div><div>However, you need to send udev notification from a kernel driver.<br> <br></div><span class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>tree configuration. (following <a href="https://yurovsky.github.io/2014/10/10/linux-uio-gpio-interrupt/" target="_blank">https://yurovsky.github.io/201<wbr>4/10/10/linux-uio-gpio-interru<wbr>pt/</a>)</div><div><br></div><div> user_io@0 {</div><div> compatible = "mydevice,generic-uio,ui_pdrv"<wbr>;</div><div> status = "okay";</div><div> interrupt-parent = <&mygpio>;</div><div> interrupts = <0 IRQ_TYPE_LEVEL_HIGH>;</div><div> };</div><div><br></div><div>Running modprobe uio_pdrv_genirq of_id="mydevice,generic-uio,ui<wbr>_pdrv" and creating /dev/uio0 using mknod (major number from cat /proc/devices | grep uio),</div><div>I couldn't see an irq entry bind to uio driver under /proc/interrupts.</div><div>Am I doing anything wrong here?</div><div><br></div><div>Other method I have tried to get notified of the gpio pin0 interrupt in user space is to poll on /sys/class/gpio/gpio0/value. But merely exporting gpio0 </div><div>wasn't sufficient as kernel should make a call to request_irq on the gpio0 interrupt line. Is there a generic driver framework (like pinctrl) that can export</div><div>a device node to register the gpio pin0 as an interrupt source that allows me to poll on its sysfs entry?</div></div></blockquote><div><br></div></span><div>All sysfs nodes can be polled as it is supported in kernel. <br></div><div>You can simply create a dummy driver and register the<br></div><div>irq and in your irq handler send udev notifications using<br></div><div>kobj.<br></div><div><br>Or<br></div><div>just update a sysfs node which can be polled from userspace.<br><br></div><div>If this answer is not sufficient then please explain in detail<br></div><div>what you are planning to achieve rather than what you are<br></div><div>doing to achieve that. <br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><br></div><div>Thanks,</div><div>Rajasekhar</div></div>
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