Re: [PATCH 9/9] iommu: arm-smmu-v3: make it explicitly non-modular

Robin Murphy
2018-11-28T12:44:24Z

On 26/11/2018 22:31, Paul Gortmaker wrote:
> The Kconfig currently controlling compilation of this code is:
>
> drivers/iommu/Kconfig:config ARM_SMMU_V3
> drivers/iommu/Kconfig: bool "ARM Ltd. System MMU Version 3 (SMMUv3) Support"
>
> ...meaning that it currently is not being built as a module by anyone.
>
> Lets remove the modular code that is essentially orphaned, so that
> when reading the driver there is no doubt it is builtin-only.
>
> Since module_platform_driver() uses the same init level priority as
> builtin_platform_driver() the init ordering remains unchanged with
> this commit.
>
> We explicitly disallow a driver unbind, since that doesn't have a
> sensible use case anyway, but unlike most drivers, we can't delete the
> function tied to the ".remove" field. This is because as of commit
> 7aa8619a66ae ("iommu/arm-smmu-v3: Implement shutdown method") the
> .remove function was given a one line wrapper and re-used to provide a
> .shutdown service. So we delete the wrapper and re-name the function
> from remove to shutdown.
>
> We add a moduleparam.h include since the file does actually declare
> some module parameters, and leaving them as such is the easiest way
> currently to remain backwards compatible with existing use cases.
>
> Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.
>
> We also delete the MODULE_LICENSE tag etc. since all that information
> is already contained at the top of the file in the comments.

With the title fixed up,

Acked-by: Robin Murphy <robin.murphy@arm.com>

> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Cc: Nate Watterson <nwatters@codeaurora.org>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: iommu@lists.linux-foundation.org
> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
> ---
> drivers/iommu/arm-smmu-v3.c | 25 +++++++++----------------
> 1 file changed, 9 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index 6947ccf26512..1189c06079d4 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -20,7 +20,8 @@
> #include <linux/interrupt.h>
> #include <linux/iommu.h>
> #include <linux/iopoll.h>
> -#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/moduleparam.h>
> #include <linux/msi.h>
> #include <linux/of.h>
> #include <linux/of_address.h>
> @@ -356,6 +357,10 @@
> #define MSI_IOVA_BASE 0x8000000
> #define MSI_IOVA_LENGTH 0x100000
>
> +/*
> + * not really modular, but the easiest way to keep compat with existing
> + * bootargs behaviour is to continue using module_param_named here.
> + */
> static bool disable_bypass = 1;
> module_param_named(disable_bypass, disable_bypass, bool, S_IRUGO);
> MODULE_PARM_DESC(disable_bypass,
> @@ -2928,37 +2933,25 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
> return 0;
> }
>
> -static int arm_smmu_device_remove(struct platform_device *pdev)
> +static void arm_smmu_device_shutdown(struct platform_device *pdev)
> {
> struct arm_smmu_device *smmu = platform_get_drvdata(pdev);
>
> arm_smmu_device_disable(smmu);
> -
> - return 0;
> -}
> -
> -static void arm_smmu_device_shutdown(struct platform_device *pdev)
> -{
> - arm_smmu_device_remove(pdev);
> }
>
> static const struct of_device_id arm_smmu_of_match[] = {
> { .compatible = "arm,smmu-v3", },
> { },
> };
> -MODULE_DEVICE_TABLE(of, arm_smmu_of_match);
>
> static struct platform_driver arm_smmu_driver = {
> .driver = {
> .name = "arm-smmu-v3",
> .of_match_table = of_match_ptr(arm_smmu_of_match),
> + .suppress_bind_attrs = true,
> },
> .probe = arm_smmu_device_probe,
> - .remove = arm_smmu_device_remove,
> .shutdown = arm_smmu_device_shutdown,
> };
> -module_platform_driver(arm_smmu_driver);
> -
> -MODULE_DESCRIPTION("IOMMU API for ARM architected SMMUv3 implementations");
> -MODULE_AUTHOR("Will Deacon <will.deacon@arm.com>");
> -MODULE_LICENSE("GPL v2");
> +builtin_platform_driver(arm_smmu_driver);
>