[PATCH 6/7] iommu/arm-smmu: Add module parameter arm-smmu=off|force_isolation

[Will Deacon]

On Tue, Sep 24, 2013 at 04:07:00PM +0100, Andreas Herrmann wrote:
>   arm-smmu=	arm-smmu driver option
> 
> 	off	Disable arm-smmu driver (ie. ignore available SMMUs)
> 
> 	force_isolation
> 		Try to attach each master device on every SMMU to a
> 		separate iommu_domain.
> 
> Default is that driver detects SMMUs but no translation is configured
> (transactions just bypass translation process).
> 
> Signed-off-by: Andreas Herrmann <andreas.herrmann at calxeda.com>
> ---
>  drivers/iommu/arm-smmu.c |   26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 3eb2259..251564e 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -399,6 +399,9 @@ struct arm_smmu_domain {
>  static DEFINE_SPINLOCK(arm_smmu_devices_lock);
>  static LIST_HEAD(arm_smmu_devices);
>  
> +static bool arm_smmu_disabled;
> +static bool arm_smmu_force_isolation;
> +
>  static struct arm_smmu_master *find_smmu_master(struct arm_smmu_device *smmu,
>  						struct device_node *dev_node)
>  {
> @@ -1837,6 +1840,9 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev)
>  	struct of_phandle_args masterspec;
>  	int num_irqs, i, err;
>  
> +	if (arm_smmu_disabled)
> +		return -ENODEV;
> +
>  	smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL);
>  	if (!smmu) {
>  		dev_err(dev, "failed to allocate arm_smmu_device\n");
> @@ -2022,6 +2028,23 @@ static struct platform_driver arm_smmu_driver = {
>  	.remove	= arm_smmu_device_remove,
>  };
>  
> +static int __init arm_smmu_parse_options(char *str)
> +{
> +	if (*str) {
> +		str++;
> +		if (!strncmp(str, "off", 3))
> +			arm_smmu_disabled = true;
> +		else if(!strncmp(str, "force_isolation", 15))
> +			arm_smmu_force_isolation = true;
> +		else {
> +			pr_warn("arm_smmu: invalid parameter (\"%s\")\n", str);
> +			return 0;
> +		}
> +	}
> +	return 1;
> +}
> +__setup("arm-smmu", arm_smmu_parse_options);

If this is going to be a common function for IOMMUs, let's instead move the
command-line parsing out into the generic IOMMU layer, then have an optional
callback into the low-level IOMMU driver for enabling/disabling it.

Will