linux-kernel - Re: [RFC][PATCH 3/5] irqchip: Allow QCOM_PDC to be loadable as a perment module

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Date:   Tue, 16 Jun 2020 16:59:58 +0530
From:   Maulik Shah <mkshah@...eaurora.org>
To:     John Stultz <john.stultz@...aro.org>,
        lkml <linux-kernel@...r.kernel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <maz@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Lina Iyer <ilina@...eaurora.org>,
        Saravana Kannan <saravanak@...gle.com>,
        Todd Kjos <tkjos@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-gpio@...r.kernel.org
Subject: Re: [RFC][PATCH 3/5] irqchip: Allow QCOM_PDC to be loadable as a
 perment module

Hi,

On 6/16/2020 11:43 AM, John Stultz wrote:
> Allows qcom-pdc driver to be loaded as a permenent module

typo: permanent

> Also, due to the fact that IRQCHIP_DECLARE becomes a no-op when
> building as a module, we have to add the platform driver hooks
> explicitly.
>
> Thanks to Saravana for his help on pointing out the
> IRQCHIP_DECLARE issue and guidance on a solution.
>
> Cc: Andy Gross <agross@...nel.org>
> Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
> Cc: Joerg Roedel <joro@...tes.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Jason Cooper <jason@...edaemon.net>
> Cc: Marc Zyngier <maz@...nel.org>
> Cc: Linus Walleij <linus.walleij@...aro.org>
> Cc: Lina Iyer <ilina@...eaurora.org>
> Cc: Saravana Kannan <saravanak@...gle.com>
> Cc: Todd Kjos <tkjos@...gle.com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: linux-arm-msm@...r.kernel.org
> Cc: iommu@...ts.linux-foundation.org
> Cc: linux-gpio@...r.kernel.org
> Signed-off-by: John Stultz <john.stultz@...aro.org>
> ---
>   drivers/irqchip/Kconfig    |  2 +-
>   drivers/irqchip/qcom-pdc.c | 30 ++++++++++++++++++++++++++++++
>   2 files changed, 31 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 29fead208cad..12765bed08f9 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -425,7 +425,7 @@ config GOLDFISH_PIC
>            for Goldfish based virtual platforms.
>   
>   config QCOM_PDC
> -	bool "QCOM PDC"
> +	tristate "QCOM PDC"
>   	depends on ARCH_QCOM
>   	select IRQ_DOMAIN_HIERARCHY
>   	help
> diff --git a/drivers/irqchip/qcom-pdc.c b/drivers/irqchip/qcom-pdc.c
> index 6ae9e1f0819d..98d74160afcd 100644
> --- a/drivers/irqchip/qcom-pdc.c
> +++ b/drivers/irqchip/qcom-pdc.c
> @@ -11,7 +11,9 @@
>   #include <linux/irqdomain.h>
>   #include <linux/io.h>
>   #include <linux/kernel.h>
> +#include <linux/module.h>
>   #include <linux/of.h>
> +#include <linux/of_irq.h>
please move this include in order after of_device.h
>   #include <linux/of_address.h>
>   #include <linux/of_device.h>
>   #include <linux/soc/qcom/irq.h>
> @@ -430,4 +432,32 @@ static int qcom_pdc_init(struct device_node *node, struct device_node *parent)
>   	return ret;
>   }
>   
> +#ifdef MODULE
> +static int qcom_pdc_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct device_node *parent = of_irq_find_parent(np);
> +
> +	return qcom_pdc_init(np, parent);
> +}
> +
> +static const struct of_device_id qcom_pdc_match_table[] = {
> +	{ .compatible = "qcom,pdc" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, qcom_pdc_match_table);
> +
> +static struct platform_driver qcom_pdc_driver = {
> +	.probe = qcom_pdc_probe,
> +	.driver = {
> +		.name = "qcom-pdc",
> +		.of_match_table = qcom_pdc_match_table,

can you please set .suppress_bind_attrs = true,

This is to prevent bind/unbind using sysfs. Once irqchip driver module 
is loaded, it shouldn't get unbind at runtime.

Thanks,
Maulik
> +	},
> +};
> +module_platform_driver(qcom_pdc_driver);
> +#else
>   IRQCHIP_DECLARE(qcom_pdc, "qcom,pdc", qcom_pdc_init);
> +#endif
> +
> +MODULE_DESCRIPTION("Qualcomm Technologies, Inc. Power Domain Controller");
> +MODULE_LICENSE("GPL v2");

-- 
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