linux-kernel - Re: [PATCH -next 0/2] allow gpio simulator be used as interrupt controller

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Date:   Mon, 26 Sep 2022 14:57:53 +0800
From:   Wei Yongjun <weiyongjun1@...wei.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next 0/2] allow gpio simulator be used as interrupt
 controller



On 2022/9/1 0:08, Bartosz Golaszewski wrote:
> On Fri, Aug 26, 2022 at 9:44 AM Wei Yongjun <weiyongjun1@...wei.com> wrote:
>>
>> This series allow gpio simulator be used as interrupt controller, the use
>> case is mockup some device which using GPIO as interrupt controller, such
>> as mcp2515 CAN device. With the dts [1], we can mockup a mcp2515 device,
>> and trigger irq by following commands:
>>
>>  $ echo pull-down > /sys/bus/gpio/devices/gpiochip0/sim_gpio0/pull
>>  $ echo pull-up > /sys/bus/gpio/devices/gpiochip0/sim_gpio0/pull
>>
>>
>> --[1]---------------------------------------------------------
>> /dts-v1/;
>>
>> #include <dt-bindings/interrupt-controller/irq.h>
>>
>> / {
>>         clk24m: clk24m {
>>                 compatible = "fixed-clock";
>>                 clock-output-names = "clk24m";
>>                 clock-frequency = <24000000>;
>>                 #clock-cells = <0>;
>>         };
>>
>>         gpio-sim {
>>                 compatible = "gpio-simulator";
>>
>>                 bank0: bank0 {
>>                         gpio-controller;
>>                         #gpio-cells = <2>;
>>                         ngpios = <16>;
>>
>>                         interrupt-controller;
>>                         #interrupt-cells = <2>;
>>
>>                         line_b-hog {
>>                                 gpio-hog;
>>                                 gpios = <0 1>;
>>                                 input;
>>                                 line-name = "irq-sim";
>>                         };
> 
> Why do you need this hog? The GPIO will be marked as requested once
> the interrupt is taken by the driver.

Sorry for reply later.

It seems that only if driver request gpio with fwnode_gpiod_get_index()
marks GPIO as request one.

If driver using request_threaded_irq() request one irq, the requested
status will not be marked. We need to use hog or request by userspace
to mark as requested.

> 
>>                 };
>>         };
>>
>>         spi: spi {
>>                 compatible = "spi-mockup";
>>
>>                 #address-cells = <1>;
>>                 #size-cells = <0>;
>>
>>                 can0: can@1 {
>>                         compatible = "microchip,mcp2515";
>>                         reg = <1>;
>>                         clocks = <&clk24m>;
>>                         interrupt-parent = <&bank0>;
>>                         interrupts = <0 IRQ_TYPE_EDGE_BOTH>;
>>                 };
>>
>>         };
>> };
>> ------------------------------><-----------------------------
>>
>> Wei Yongjun (2):
>>   genirq/irq_sim: Allow both one and two cell bindings
>>   gpio: sim: make gpio simulator can be used as interrupt controller
>>
>>  drivers/gpio/gpio-sim.c | 2 +-
>>  kernel/irq/irq_sim.c    | 1 +
>>  2 files changed, 2 insertions(+), 1 deletion(-)
>>
>> --
>> 2.34.1
>>
> 
> Can you add some info about this to the documentation?

Will do that

Thanks,
Wei Yongjun