linux-kernel - Re: [PATCH 4/5] PCI: aardvark: Implement driver 'remove' function and allow to build it as module

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Message-ID: <20200729184809.GA569408@bogus>
Date:   Wed, 29 Jul 2020 12:48:09 -0600
From:   Rob Herring <robh@...nel.org>
To:     Marek Behún <marek.behun@....cz>
Cc:     linux-pci@...r.kernel.org, Tomasz Maciej Nowak <tmn505@...il.com>,
        Gregory Clement <gregory.clement@...tlin.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        linux-kernel@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
        Xogium <contact@...ium.me>,
        Pali Rohár <pali@...nel.org>
Subject: Re: [PATCH 4/5] PCI: aardvark: Implement driver 'remove' function
 and allow to build it as module

On Wed, Jul 15, 2020 at 04:25:56PM +0200, Marek Behún wrote:
> From: Pali Rohár <pali@...nel.org>
> 
> Providing driver's 'remove' function allows kernel to bind and unbind devices
> from aardvark driver. It also allows to build aardvark driver as a module.
> 
> Compiling aardvark as a module simplifies development and debugging of
> this driver as it can be reloaded at runtime without the need to reboot
> to new kernel.
> 
> Signed-off-by: Pali Rohár <pali@...nel.org>
> Reviewed-by: Marek Behún <marek.behun@....cz>
> ---
>  drivers/pci/controller/Kconfig        |  2 +-
>  drivers/pci/controller/pci-aardvark.c | 25 ++++++++++++++++++++++---
>  2 files changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
> index adddf21fa381..f9da5ff2c517 100644
> --- a/drivers/pci/controller/Kconfig
> +++ b/drivers/pci/controller/Kconfig
> @@ -12,7 +12,7 @@ config PCI_MVEBU
>  	select PCI_BRIDGE_EMUL
>  
>  config PCI_AARDVARK
> -	bool "Aardvark PCIe controller"
> +	tristate "Aardvark PCIe controller"
>  	depends on (ARCH_MVEBU && ARM64) || COMPILE_TEST
>  	depends on OF
>  	depends on PCI_MSI_IRQ_DOMAIN
> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index d5f58684d962..0a5aa6d77f5d 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -14,6 +14,7 @@
>  #include <linux/irq.h>
>  #include <linux/irqdomain.h>
>  #include <linux/kernel.h>
> +#include <linux/module.h>
>  #include <linux/pci.h>
>  #include <linux/init.h>
>  #include <linux/phy/phy.h>
> @@ -1114,6 +1115,7 @@ static int advk_pcie_probe(struct platform_device *pdev)
>  
>  	pcie = pci_host_bridge_priv(bridge);
>  	pcie->pdev = pdev;
> +	platform_set_drvdata(pdev, pcie);
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	pcie->base = devm_ioremap_resource(dev, res);
> @@ -1204,18 +1206,35 @@ static int advk_pcie_probe(struct platform_device *pdev)
>  	return 0;
>  }
>  
> +static int advk_pcie_remove(struct platform_device *pdev)
> +{
> +	struct advk_pcie *pcie = platform_get_drvdata(pdev);
> +	struct pci_host_bridge *bridge = pci_host_bridge_from_priv(pcie);
> +
> +	pci_stop_root_bus(bridge->bus);
> +	pci_remove_root_bus(bridge->bus);

Based on pci_host_common_remove() implementation, doesn't this need a 
lock around it (pci_lock_rescan_remove)?

We should probably have a common function (say pci_bridge_remove) to 
implement this. You could use pci_host_common_remove(), but you'd have 
to adjust drvdata.

> +
> +	advk_pcie_remove_msi_irq_domain(pcie);
> +	advk_pcie_remove_irq_domain(pcie);
> +
> +	return 0;
> +}
> +
>  static const struct of_device_id advk_pcie_of_match_table[] = {
>  	{ .compatible = "marvell,armada-3700-pcie", },
>  	{},
>  };
> +MODULE_DEVICE_TABLE(of, advk_pcie_of_match_table);
>  
>  static struct platform_driver advk_pcie_driver = {
>  	.driver = {
>  		.name = "advk-pcie",
>  		.of_match_table = advk_pcie_of_match_table,
> -		/* Driver unloading/unbinding currently not supported */
> -		.suppress_bind_attrs = true,
>  	},
>  	.probe = advk_pcie_probe,
> +	.remove = advk_pcie_remove,
>  };
> -builtin_platform_driver(advk_pcie_driver);
> +module_platform_driver(advk_pcie_driver);
> +
> +MODULE_DESCRIPTION("Aardvark PCIe controller");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.26.2
>