Re: [PATCH v9 14/16] iommu/exynos: add support for power management subsystems.

[Tomasz Figa <tomasz.figa-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hi KyongHo,

nit: Please drop the trailing dot at the end of patch subject.

On Thursday 08 of August 2013 18:41:17 Cho KyongHo wrote:
> This adds support for Advance Power Management and Runtime Power
> Management.

This patch adds support for system-wide and runtime power management.

> Since System MMU is located in the same local power domain of its
> master H/W, System MMU must be initialized before it is working if
> its power domain was ever turned off. TLB invalidation according to
> unmapping on page tables must also be performed while power domain is
> turned on.
> 
> This patch ensures that resume and runtime_resume(restore_state)
> functions in this driver is called before the calls to resume and
> runtime_resume callback functions in the drivers of master H/Ws.
> Likewise, suspend and runtime_suspend(save_state) functions in this
> driver is called after the calls to suspend and runtime_suspend in the
> drivers of master H/Ws.
> 
> In order to get benefit of this support, the master H/W and its System
> MMU must resides in the same power domain in terms of Linux kernel. If
> a master H/W does not use generic I/O power domain, its driver must
> call iommu_attach_device() after its local power domain is turned on,
> iommu_detach_device before turned off.

I don't get the point of this last paragraph. What a power domain can be 
in other terms? Is there any other way to support power domains on Exynos 
than generic power domains?

> Signed-off-by: Cho KyongHo <pullip.cho-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> ---
>  drivers/iommu/exynos-iommu.c |  235
> +++++++++++++++++++++++++++++++++++++++++- 1 files changed, 231
> insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index 9e64483..56aead9 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -28,6 +28,7 @@
>  #include <linux/export.h>
>  #include <linux/of.h>
>  #include <linux/of_platform.h>
> +#include <linux/pm_domain.h>
>  #include <linux/notifier.h>
> 
>  #include <asm/cacheflush.h>
> @@ -186,6 +187,7 @@ struct sysmmu_drvdata {
>  	int activations;
>  	rwlock_t lock;
>  	struct iommu_domain *domain;
> +	bool runtime_active;
>  	unsigned long pgtable;
>  	void __iomem *sfrbases[0];
>  };
> @@ -438,7 +440,8 @@ static bool __sysmmu_disable(struct sysmmu_drvdata
> *data) data->pgtable = 0;
>  		data->domain = NULL;
> 
> -		__sysmmu_disable_nocount(data);
> +		if (data->runtime_active)
> +			__sysmmu_disable_nocount(data);
> 
>  		dev_dbg(data->sysmmu, "Disabled\n");
>  	} else  {
> @@ -505,7 +508,8 @@ static int __sysmmu_enable(struct sysmmu_drvdata
> *data, data->pgtable = pgtable;
>  		data->domain = domain;
> 
> -		__sysmmu_enable_nocount(data);
> +		if (data->runtime_active)
> +			__sysmmu_enable_nocount(data);
> 
>  		dev_dbg(data->sysmmu, "Enabled\n");
>  	} else {
> @@ -609,7 +613,7 @@ static void sysmmu_tlb_invalidate_entry(struct
> device *dev, unsigned long iova) data =
> dev_get_drvdata(client->sysmmu[i]);
> 
>  		read_lock_irqsave(&data->lock, flags);
> -		if (is_sysmmu_active(data)) {
> +		if (is_sysmmu_active(data) && data->runtime_active) {
>  			int i;
>  			clk_enable(data->clk_master);
>  			for (i = 0; i < data->nsfrs; i++)
> @@ -637,7 +641,8 @@ void exynos_sysmmu_tlb_invalidate(struct device
> *dev) data = dev_get_drvdata(client->sysmmu[i]);
> 
>  		read_lock_irqsave(&data->lock, flags);
> -		if (is_sysmmu_active(data)) {
> +		if (is_sysmmu_active(data) &&
> +				data->runtime_active) {

nit: The whole if condition fits into single line.

>  			int i;
>  			for (i = 0; i < data->nsfrs; i++) {
>  				clk_enable(data->clk_master);
> @@ -711,6 +716,8 @@ static int __init exynos_sysmmu_probe(struct
> platform_device *pdev) }
>  	}
> 
> +	pm_runtime_enable(dev);
> +
>  	data->sysmmu = dev;
> 
>  	data->clk = devm_clk_get(dev, "sysmmu");
> @@ -736,6 +743,8 @@ static int __init exynos_sysmmu_probe(struct
> platform_device *pdev) return ret;
>  	}
> 
> +	data->runtime_active = !pm_runtime_enabled(dev);
> +
>  	rwlock_init(&data->lock);
> 
>  	platform_set_drvdata(pdev, data);
> @@ -744,6 +753,34 @@ static int __init exynos_sysmmu_probe(struct
> platform_device *pdev) return ret;
>  }
> 
> +#ifdef CONFIG_PM_SLEEP
> +static int sysmmu_suspend(struct device *dev)
> +{
> +	struct sysmmu_drvdata *data = dev_get_drvdata(dev);
> +	unsigned long flags;
> +	read_lock_irqsave(&data->lock, flags);
> +	if (is_sysmmu_active(data) &&
> +		(!pm_runtime_enabled(dev) || data->runtime_active))
> +		__sysmmu_disable_nocount(data);
> +	read_unlock_irqrestore(&data->lock, flags);
> +	return 0;
> +}
> +
> +static int sysmmu_resume(struct device *dev)
> +{
> +	struct sysmmu_drvdata *data = dev_get_drvdata(dev);
> +	unsigned long flags;
> +	read_lock_irqsave(&data->lock, flags);
> +	if (is_sysmmu_active(data) &&
> +		(!pm_runtime_enabled(dev) || data->runtime_active))
> +		__sysmmu_enable_nocount(data);
> +	read_unlock_irqrestore(&data->lock, flags);
> +	return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(sysmmu_pm_ops, sysmmu_suspend, sysmmu_resume);
> +
>  #ifdef CONFIG_OF
>  static struct of_device_id sysmmu_of_match[] __initconst = {
>  	{ .compatible	= "samsung,exynos4210-sysmmu", },
> @@ -756,6 +793,7 @@ static struct platform_driver exynos_sysmmu_driver
> __refdata = { .driver	= {
>  		.owner		= THIS_MODULE,
>  		.name		= "exynos-sysmmu",
> +		.pm		= &sysmmu_pm_ops,
>  		.of_match_table	= of_match_ptr(sysmmu_of_match),
>  	}
>  };
> @@ -1141,6 +1179,163 @@ static int __init exynos_iommu_init(void)
>  }
>  subsys_initcall(exynos_iommu_init);
> 
> +#ifdef CONFIG_PM_SLEEP
> +static int sysmmu_pm_genpd_suspend(struct device *dev)
> +{
> +	struct exynos_iommu_client *client = dev->archdata.iommu;
> +	int ret = 0;
> +	int i;
> +
> +	for (i = 0; i < client->num_sysmmu; i++) {
> +		ret = pm_generic_suspend(client->sysmmu[i]);
> +		if (ret)
> +			break;
> +	}
> +
> +	if (!ret)
> +		ret = pm_generic_suspend(dev);
> +
> +	if (ret) {
> +		int j;
> +
> +		for (j = 0; j < i; j++)
> +			pm_generic_resume(client->sysmmu[j]);
> +	}
> +
> +	return ret;
> +}
> +
> +static int sysmmu_pm_genpd_resume(struct device *dev)
> +{
> +	struct exynos_iommu_client *client = dev->archdata.iommu;
> +	int ret = 0;
> +	int i;
> +
> +	for (i = 0; i < client->num_sysmmu; i++) {
> +		ret = pm_generic_resume(client->sysmmu[i]);
> +		if (ret)
> +			break;

Error handling here can be cleaned up a lot.

s/break/goto err_suspend/

> +	}
> +
> +	if (!ret)

Now you can drop this check.

> +		ret = pm_generic_resume(dev);

	ret = pm_generic_resume(dev);
	if (ret)
		goto err_suspend;

	return 0;

> +

err_suspend:
> +	if (ret) {

This check can be dropped here as well now.

> +		int j;
> +
> +		for (j = 0; j < i; j++)
> +			pm_generic_suspend(client->sysmmu[j]);
> +	}
> +
> +	return ret;
> +}
> +#endif

Best regards,
Tomasz