linux-kernel - Re: [PATCH 6/7] Revert "iommu/arm-smmu: Make arm-smmu explicitly non-modular"

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Date:   Wed, 30 Oct 2019 17:09:41 -0600
From:   Jordan Crouse <jcrouse@...eaurora.org>
To:     Will Deacon <will@...nel.org>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Robin Murphy <robin.murphy@....com>
Subject: Re: [PATCH 6/7] Revert "iommu/arm-smmu: Make arm-smmu explicitly
 non-modular"

On Wed, Oct 30, 2019 at 02:51:11PM +0000, Will Deacon wrote:
> This reverts commit addb672f200f4e99368270da205320b83efe01a0.
> 
> Let's get the SMMU driver building as a module, which means putting
> back some dead code that we used to carry.
> 
> Signed-off-by: Will Deacon <will@...nel.org>
> ---
>  drivers/iommu/arm-smmu.c | 32 +++++++++++++++++++-------------
>  1 file changed, 19 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 7c503a6bc585..53bbe0663b9e 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -27,8 +27,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/iopoll.h>
> -#include <linux/init.h>
> -#include <linux/moduleparam.h>
> +#include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_address.h>
>  #include <linux/of_device.h>
> @@ -59,10 +58,6 @@
>  #define MSI_IOVA_LENGTH			0x100000
>  
>  static int force_stage;
> -/*
> - * not really modular, but the easiest way to keep compat with existing
> - * bootargs behaviour is to continue using module_param() here.
> - */
>  module_param(force_stage, int, S_IRUGO);
>  MODULE_PARM_DESC(force_stage,
>  	"Force SMMU mappings to be installed at a particular stage of translation. A value of '1' or '2' forces the corresponding stage. All other values are ignored (i.e. no stage is forced). Note that selecting a specific stage will disable support for nested translation.");
> @@ -1878,6 +1873,7 @@ static const struct of_device_id arm_smmu_of_match[] = {
>  	{ .compatible = "qcom,smmu-v2", .data = &qcom_smmuv2 },
>  	{ },
>  };
> +MODULE_DEVICE_TABLE(of, arm_smmu_of_match);
>  
>  #ifdef CONFIG_ACPI
>  static int acpi_smmu_get_data(u32 model, struct arm_smmu_device *smmu)
> @@ -2165,12 +2161,12 @@ static int arm_smmu_legacy_bus_init(void)
>  }
>  device_initcall_sync(arm_smmu_legacy_bus_init);
>  
> -static void arm_smmu_device_shutdown(struct platform_device *pdev)
> +static int arm_smmu_device_remove(struct platform_device *pdev)
>  {
>  	struct arm_smmu_device *smmu = platform_get_drvdata(pdev);
>  
>  	if (!smmu)
> -		return;
> +		return -ENODEV;
>  
>  	if (!bitmap_empty(smmu->context_map, ARM_SMMU_MAX_CBS))
>  		dev_err(&pdev->dev, "removing device with active domains!\n");
> @@ -2186,6 +2182,12 @@ static void arm_smmu_device_shutdown(struct platform_device *pdev)
>  		clk_bulk_disable(smmu->num_clks, smmu->clks);
>  
>  	clk_bulk_unprepare(smmu->num_clks, smmu->clks);
> +	return 0;
> +}
> +
> +static void arm_smmu_device_shutdown(struct platform_device *pdev)
> +{
> +	arm_smmu_device_remove(pdev);
>  }
>  
>  static int __maybe_unused arm_smmu_runtime_resume(struct device *dev)
> @@ -2235,12 +2237,16 @@ static const struct dev_pm_ops arm_smmu_pm_ops = {
>  
>  static struct platform_driver arm_smmu_driver = {
>  	.driver	= {
> -		.name			= "arm-smmu",
> -		.of_match_table		= of_match_ptr(arm_smmu_of_match),
> -		.pm			= &arm_smmu_pm_ops,
> -		.suppress_bind_attrs	= true,
> +		.name		= "arm-smmu",
> +		.of_match_table	= of_match_ptr(arm_smmu_of_match),
> +		.pm		= &arm_smmu_pm_ops,
>  	},
>  	.probe	= arm_smmu_device_probe,
> +	.remove	= arm_smmu_device_remove,
>  	.shutdown = arm_smmu_device_shutdown,
>  };
> -builtin_platform_driver(arm_smmu_driver);
> +module_platform_driver(arm_smmu_driver);

I know this is a revert, but wouldn't you still want to be at device_init()
level for built in drivers? It always preferable to not defer if given the
choice to do so and device_init() is the right level for this driver IMO.

Jordan

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