Message-id: <6639650.hgn0t6JFZ2@amdc1032>
Date:	Fri, 02 Aug 2013 19:32:18 +0200
From:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:	Cho KyongHo <pullip.cho@...sung.com>
Cc:	'Linux ARM Kernel' <linux-arm-kernel@...ts.infradead.org>,
	'Linux IOMMU' <iommu@...ts.linux-foundation.org>,
	'Linux Kernel' <linux-kernel@...r.kernel.org>,
	'Linux Samsung SOC' <linux-samsung-soc@...r.kernel.org>,
	'Hyunwoong Kim' <khw0178.kim@...sung.com>,
	'Joerg Roedel' <joro@...tes.org>,
	'Kukjin Kim' <kgene.kim@...sung.com>,
	'Prathyush' <prathyush.k@...sung.com>,
	'Rahul Sharma' <rahul.sharma@...sung.com>,
	'Subash Patel' <supash.ramaswamy@...aro.org>,
	'Keyyoung Park' <keyyoung.park@...sung.com>,
	'Grant Grundler' <grundler@...omium.org>,
	'Antonios Motakis' <a.motakis@...tualopensystems.com>,
	kvmarm@...ts.cs.columbia.edu,
	'Sachin Kamat' <sachin.kamat@...aro.org>
Subject: Re: [PATCH v8 10/12] iommu/exynos: add bus notifier for registering
 System MMU


Hi,

On Friday, July 26, 2013 08:30:17 PM Cho KyongHo wrote:
> When a device driver is registered, all constructs to handle System MMU
> is prepared by bus notifier call.

Patch description could be improved greatly by documenting what the patch
is doing and it does a lot more than simply adding bus notifier.

The patch can be also split further (at least code adding support for
muplitple System MMUs per struct exynos_iommu_client instance could be
separate which would make review a lot easier as the code wouldn't be
moved around so much).

Could you also tell me how (on which SoC/board and with what drivers) are
you testing these changes? I've tried to test v7 with FIMC and MFC devices
(on EXYNOS4210 based Universal C210 board) but as soon as I added actual
IOMMU mappings (none of your patches in this series does it BTW) I've
encountered problems (namely lockup related to clocks usage, probably
related to "master" clock, I haven't had time to debug it further yet).

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

> Signed-off-by: Cho KyongHo <pullip.cho@...sung.com>
> ---
>  drivers/iommu/exynos-iommu.c |  708 ++++++++++++++++++++++++++++++++---------
>  1 files changed, 552 insertions(+), 156 deletions(-)
> 
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index f9853fe..c62c244 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -27,6 +27,9 @@
>  #include <linux/memblock.h>
>  #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>
>  #include <asm/pgtable.h>
> @@ -80,7 +83,13 @@
>  #define CTRL_BLOCK	0x7
>  #define CTRL_DISABLE	0x0
>  
> +#define CFG_LRU		0x1
> +#define CFG_QOS(n)	((n & 0xF) << 7)
> +#define CFG_MASK	0x0150FFFF /* Selecting bit 0-15, 20, 22 and 24 */
> +#define CFG_ACGEN	(1 << 24) /* System MMU 3.3 only */
> +#define CFG_SYSSEL	(1 << 22) /* System MMU 3.2 only */
>  #define CFG_FLPDCACHE	(1 << 20) /* System MMU 3.2+ only */
> +#define CFG_SHAREABLE	(1 << 12) /* System MMU 3.x only */
>  
>  #define REG_MMU_CTRL		0x000
>  #define REG_MMU_CFG		0x004
> @@ -154,6 +163,14 @@ static char *sysmmu_fault_name[SYSMMU_FAULTS_NUM] = {
>  	"UNKNOWN FAULT"
>  };
>  
> +struct exynos_iommu_client {
> +	struct list_head node;	/* entry of exynos_iommu_domain.clients */
> +	struct device *dev;
> +	spinlock_t lock;
> +	int num_sysmmu;
> +	struct device *sysmmu[0];
> +};
> +
>  struct exynos_iommu_domain {
>  	struct list_head clients; /* list of sysmmu_drvdata.node */
>  	unsigned long *pgtable; /* lv1 page table, 16KB */
> @@ -165,12 +182,14 @@ struct exynos_iommu_domain {
>  struct sysmmu_drvdata {
>  	struct list_head node; /* entry of exynos_iommu_domain.clients */
>  	struct device *sysmmu;	/* System MMU's device descriptor */
> -	struct device *dev;	/* Owner of system MMU */
> +	struct device *master;	/* Owner of system MMU */
>  	int nsfrs;
>  	struct clk *clk;
> +	struct clk *clk_master;
>  	int activations;
>  	rwlock_t lock;
>  	struct iommu_domain *domain;
> +	bool runtime_active;
>  	unsigned long pgtable;
>  	void __iomem *sfrbases[0];
>  };
> @@ -245,7 +264,6 @@ static void __sysmmu_tlb_invalidate_entry(void __iomem *sfrbase,
>  static void __sysmmu_set_ptbase(void __iomem *sfrbase,
>  				       unsigned long pgd)
>  {
> -	__raw_writel(0x1, sfrbase + REG_MMU_CFG); /* 16KB LV1, LRU */
>  	__raw_writel(pgd, sfrbase + REG_PT_BASE_ADDR);
>  
>  	__sysmmu_tlb_invalidate(sfrbase);
> @@ -273,6 +291,7 @@ void exynos_sysmmu_set_prefbuf(struct device *dev,
>  	if (!is_sysmmu_active(data))
>  		goto finish;
>  
> +	clk_enable(data->clk_master);
>  	for (i = 0; i < data->nsfrs; i++) {
>  		if ((readl(data->sfrbases[i] + REG_MMU_VERSION) >> 28) == 3) {
>  			if (!sysmmu_block(data->sfrbases[i]))
> @@ -298,6 +317,7 @@ void exynos_sysmmu_set_prefbuf(struct device *dev,
>  			sysmmu_unblock(data->sfrbases[i]);
>  		}
>  	}
> +	clk_disable(data->clk_master);
>  finish:
>  	read_unlock_irqrestore(&data->lock, flags);
>  }
> @@ -331,12 +351,13 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
>  {
>  	/* SYSMMU is in blocked when interrupt occurred. */
>  	struct sysmmu_drvdata *data = dev_id;
> +	struct exynos_iommu_client *client = NULL;
>  	enum exynos_sysmmu_inttype itype;
>  	unsigned long addr = -1;
> -
>  	int i, ret = -ENOSYS;
>  
> -	read_lock(&data->lock);
> +	if (data->master)
> +		client = data->master->archdata.iommu;
>  
>  	WARN_ON(!is_sysmmu_active(data));
>  
> @@ -348,6 +369,10 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
>  			break;
>  	}
>  
> +	if (client)
> +		spin_lock(&client->lock);
> +	read_lock(&data->lock);
> +
>  	if (i == data->nsfrs) {
>  		itype = SYSMMU_FAULT_UNKNOWN;
>  	} else {
> @@ -361,7 +386,7 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
>  	}
>  
>  	if (data->domain)
> -		ret = report_iommu_fault(data->domain, data->dev,
> +		ret = report_iommu_fault(data->domain, data->master,
>  				addr, itype);
>  
>  	if (!ret && (itype != SYSMMU_FAULT_UNKNOWN))
> @@ -378,177 +403,251 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
>  		sysmmu_unblock(data->sfrbases[i]);
>  
>  	read_unlock(&data->lock);
> +	if (client)
> +		spin_unlock(&client->lock);
>  
>  	return IRQ_HANDLED;
>  }
>  
> -static bool __exynos_sysmmu_disable(struct sysmmu_drvdata *data)
> +static void __sysmmu_disable_nocount(struct sysmmu_drvdata *data)
>  {
> -	unsigned long flags;
> -	bool disabled = false;
>  	int i;
>  
> -	write_lock_irqsave(&data->lock, flags);
> +	clk_enable(data->clk_master);
> +	for (i = 0; i < data->nsfrs; i++) {
> +		__raw_writel(CTRL_DISABLE,
> +				data->sfrbases[i] + REG_MMU_CTRL);
> +		__raw_writel(0, data->sfrbases[i] + REG_MMU_CFG);
> +	}
>  
> -	if (!set_sysmmu_inactive(data))
> -		goto finish;
> +	clk_disable(data->clk);
> +	clk_disable(data->clk_master);
> +}
>  
> -	for (i = 0; i < data->nsfrs; i++)
> -		__raw_writel(CTRL_DISABLE, data->sfrbases[i] + REG_MMU_CTRL);
> +static bool __sysmmu_disable(struct sysmmu_drvdata *data)
> +{
> +	bool disabled;
> +	unsigned long flags;
>  
> -	if (data->clk)
> -		clk_disable(data->clk);
> +	write_lock_irqsave(&data->lock, flags);
>  
> -	disabled = true;
> -	data->pgtable = 0;
> -	data->domain = NULL;
> -finish:
> -	write_unlock_irqrestore(&data->lock, flags);
> +	disabled = set_sysmmu_inactive(data);
> +
> +	if (disabled) {
> +		data->pgtable = 0;
> +		data->domain = NULL;
> +
> +		if (data->runtime_active)
> +			__sysmmu_disable_nocount(data);
>  
> -	if (disabled)
>  		dev_dbg(data->sysmmu, "Disabled\n");
> -	else
> -		dev_dbg(data->sysmmu, "%d times left to be disabled\n",
> +	} else  {
> +		dev_dbg(data->sysmmu, "%d times left to disable\n",
>  					data->activations);
> +	}
> +
> +	write_unlock_irqrestore(&data->lock, flags);
>  
>  	return disabled;
>  }
>  
> -/* __exynos_sysmmu_enable: Enables System MMU
> - *
> - * returns -error if an error occurred and System MMU is not enabled,
> - * 0 if the System MMU has been just enabled and 1 if System MMU was already
> - * enabled before.
> - */
> -static int __exynos_sysmmu_enable(struct sysmmu_drvdata *data,
> +
> +static void __sysmmu_init_config(struct sysmmu_drvdata *data, int idx)
> +{
> +	unsigned long cfg = CFG_LRU | CFG_QOS(15);
> +	int maj, min = 0;
> +
> +	maj = __sysmmu_version(data, idx, &min);
> +	if (maj == 3) {
> +		if (min > 1) {
> +			cfg |= CFG_FLPDCACHE;
> +			cfg |= (min == 2) ? CFG_SYSSEL : CFG_ACGEN;
> +		}
> +	}
> +
> +	__raw_writel(cfg, data->sfrbases[idx] + REG_MMU_CFG);
> +}
> +
> +static void __sysmmu_enable_nocount(struct sysmmu_drvdata *data)
> +{
> +	int i;
> +
> +	clk_enable(data->clk_master);
> +	clk_enable(data->clk);
> +
> +	for (i = 0; i < data->nsfrs; i++) {
> +		__raw_writel(CTRL_BLOCK, data->sfrbases[i] + REG_MMU_CTRL);
> +
> +		__sysmmu_init_config(data, i);
> +
> +		__sysmmu_set_ptbase(data->sfrbases[i], data->pgtable);
> +
> +		__raw_writel(CTRL_ENABLE, data->sfrbases[i] + REG_MMU_CTRL);
> +	}
> +	clk_disable(data->clk_master);
> +}
> +
> +static int __sysmmu_enable(struct sysmmu_drvdata *data,
>  			unsigned long pgtable, struct iommu_domain *domain)
>  {
> -	int i, ret = 0;
> +	int ret = 0;
>  	unsigned long flags;
>  
>  	write_lock_irqsave(&data->lock, flags);
> +	if (set_sysmmu_active(data)) {
> +		data->pgtable = pgtable;
> +		data->domain = domain;
>  
> -	if (!set_sysmmu_active(data)) {
> -		if (WARN_ON(pgtable != data->pgtable)) {
> -			ret = -EBUSY;
> -			set_sysmmu_inactive(data);
> -		} else {
> -			ret = 1;
> -		}
> +		if (data->runtime_active)
> +			__sysmmu_enable_nocount(data);
>  
> -		dev_dbg(data->sysmmu, "Already enabled\n");
> -		goto finish;
> +		dev_dbg(data->sysmmu, "Enabled\n");
> +	} else {
> +		ret = (pgtable == data->pgtable) ? 1 : -EBUSY;
> +
> +		dev_dbg(data->sysmmu, "already enabled\n");
>  	}
>  
> -	if (data->clk)
> -		clk_enable(data->clk);
> +	if (WARN_ON(ret < 0))
> +		set_sysmmu_inactive(data); /* decrement count */
>  
> -	data->pgtable = pgtable;
> +	write_unlock_irqrestore(&data->lock, flags);
>  
> -	for (i = 0; i < data->nsfrs; i++) {
> -		unsigned int min;
> +	return ret;
> +}
>  
> -		__sysmmu_set_ptbase(data->sfrbases[i], pgtable);
> +/* __exynos_sysmmu_enable: Enables System MMU
> + *
> + * returns -error if an error occurred and System MMU is not enabled,
> + * 0 if the System MMU has been just enabled and 1 if System MMU was already
> + * enabled before.
> + */
> +static int __exynos_sysmmu_enable(struct device *dev, unsigned long pgtable,
> +				  struct iommu_domain *domain)
> +{
> +	int ret = 0;
> +	unsigned long flags;
> +	struct exynos_iommu_client *client = dev->archdata.iommu;
> +	int i;
>  
> -		if ((__sysmmu_version(data, i, &min) == 3) && (min > 1)) {
> -			unsigned long cfg;
> -			cfg = __raw_readl(data->sfrbases[i] + REG_MMU_CFG);
> -			__raw_writel(cfg | CFG_FLPDCACHE,
> -					data->sfrbases[i] + REG_MMU_CFG);
> -		}
> +	if (WARN_ON(!client))
> +		return -ENODEV;
>  
> -		__raw_writel(CTRL_ENABLE, data->sfrbases[i] + REG_MMU_CTRL);
> -	}
> +	spin_lock_irqsave(&client->lock, flags);
>  
> -	data->domain = domain;
> +	for (i = 0; i < client->num_sysmmu; i++) {
> +		struct sysmmu_drvdata *data =
> +				dev_get_drvdata(client->sysmmu[i]);
> +		ret = __sysmmu_enable(data, pgtable, domain);
> +		if (ret < 0) {
> +			int j;
> +			for (j = 0; j < i; j++)
> +				__sysmmu_disable(data);
> +			break;
> +		} else {
> +			data->master = dev;
> +		}
> +	}
>  
> -	dev_dbg(data->sysmmu, "Enabled\n");
> -finish:
> -	write_unlock_irqrestore(&data->lock, flags);
> +	spin_unlock_irqrestore(&client->lock, flags);
>  
>  	return ret;
>  }
>  
>  int exynos_sysmmu_enable(struct device *dev, unsigned long pgtable)
>  {
> -	struct sysmmu_drvdata *data = dev_get_drvdata(dev->archdata.iommu);
>  	int ret;
>  
>  	BUG_ON(!memblock_is_memory(pgtable));
>  
> -	ret = pm_runtime_get_sync(data->sysmmu);
> -	if (ret < 0) {
> -		dev_dbg(data->sysmmu, "Failed to enable\n");
> -		return ret;
> -	}
> -
> -	ret = __exynos_sysmmu_enable(data, pgtable, NULL);
> -	if (WARN_ON(ret < 0)) {
> -		pm_runtime_put(data->sysmmu);
> -		dev_err(data->sysmmu,
> -			"Already enabled with page table %#lx\n",
> -			data->pgtable);
> -	} else {
> -		data->dev = dev;
> -	}
> +	ret = __exynos_sysmmu_enable(dev, pgtable, NULL);
>  
>  	return ret;
>  }
>  
>  static bool exynos_sysmmu_disable(struct device *dev)
>  {
> -	struct sysmmu_drvdata *data = dev_get_drvdata(dev->archdata.iommu);
> -	bool disabled;
> +	unsigned long flags;
> +	bool disabled = true;
> +	struct exynos_iommu_client *client = dev->archdata.iommu;
> +	int i;
>  
> -	disabled = __exynos_sysmmu_disable(data);
> -	pm_runtime_put(data->sysmmu);
> +	if (WARN_ON(!client))
> +		return true;
> +
> +	spin_lock_irqsave(&client->lock, flags);
> +
> +	/* Every call to __sysmmu_disable() must return same result */
> +	for (i = 0; i < client->num_sysmmu; i++) {
> +		struct sysmmu_drvdata *data =
> +				dev_get_drvdata(client->sysmmu[i]);
> +		disabled = __sysmmu_disable(data);
> +		if (disabled)
> +			data->master = NULL;
> +	}
> +
> +	spin_unlock_irqrestore(&client->lock, flags);
>  
>  	return disabled;
>  }
>  
>  static void sysmmu_tlb_invalidate_entry(struct device *dev, unsigned long iova)
>  {
> -	unsigned long flags;
> -	struct sysmmu_drvdata *data = dev_get_drvdata(dev->archdata.iommu);
> +	struct exynos_iommu_client *client = dev->archdata.iommu;
> +	int i;
>  
> -	read_lock_irqsave(&data->lock, flags);
> +	for (i = 0; i < client->num_sysmmu; i++) {
> +		unsigned long flags;
> +		struct sysmmu_drvdata *data;
>  
> -	if (is_sysmmu_active(data)) {
> -		int i;
> -		for (i = 0; i < data->nsfrs; i++) {
> -			if (sysmmu_block(data->sfrbases[i])) {
> +		data = dev_get_drvdata(client->sysmmu[i]);
> +
> +		read_lock_irqsave(&data->lock, flags);
> +		if (is_sysmmu_active(data) && data->runtime_active) {
> +			int i;
> +			clk_enable(data->clk_master);
> +			for (i = 0; i < data->nsfrs; i++)
>  				__sysmmu_tlb_invalidate_entry(
>  						data->sfrbases[i], iova);
> -				sysmmu_unblock(data->sfrbases[i]);
> -			}
> +			clk_disable(data->clk_master);
> +		} else {
> +			dev_dbg(dev,
> +				"disabled. Skipping TLB invalidation @ %#lx\n",
> +				iova);
>  		}
> -	} else {
> -		dev_dbg(data->sysmmu, "Disabled. Skipping invalidating TLB.\n");
> +		read_unlock_irqrestore(&data->lock, flags);
>  	}
> -
> -	read_unlock_irqrestore(&data->lock, flags);
>  }
>  
>  void exynos_sysmmu_tlb_invalidate(struct device *dev)
>  {
> -	unsigned long flags;
> -	struct sysmmu_drvdata *data = dev_get_drvdata(dev->archdata.iommu);
> -
> -	read_lock_irqsave(&data->lock, flags);
> +	struct exynos_iommu_client *client = dev->archdata.iommu;
> +	int i;
>  
> -	if (is_sysmmu_active(data)) {
> -		int i;
> -		for (i = 0; i < data->nsfrs; i++) {
> -			if (sysmmu_block(data->sfrbases[i])) {
> -				__sysmmu_tlb_invalidate(data->sfrbases[i]);
> -				sysmmu_unblock(data->sfrbases[i]);
> +	for (i = 0; i < client->num_sysmmu; i++) {
> +		unsigned long flags;
> +		struct sysmmu_drvdata *data;
> +
> +		data = dev_get_drvdata(client->sysmmu[i]);
> +
> +		read_lock_irqsave(&data->lock, flags);
> +		if (is_sysmmu_active(data) &&
> +				data->runtime_active) {
> +			int i;
> +			for (i = 0; i < data->nsfrs; i++) {
> +				clk_enable(data->clk_master);
> +				if (sysmmu_block(data->sfrbases[i])) {
> +					__sysmmu_tlb_invalidate(
> +							data->sfrbases[i]);
> +					sysmmu_unblock(data->sfrbases[i]);
> +				}
> +				clk_disable(data->clk_master);
>  			}
> +		} else {
> +			dev_dbg(dev, "disabled. Skipping TLB invalidation\n");
>  		}
> -	} else {
> -		dev_dbg(data->sysmmu, "Disabled. Skipping invalidating TLB.\n");
> +		read_unlock_irqrestore(&data->lock, flags);
>  	}
> -
> -	read_unlock_irqrestore(&data->lock, flags);
>  }
>  
>  static int __init exynos_sysmmu_probe(struct platform_device *pdev)
> @@ -610,12 +709,32 @@ static int __init exynos_sysmmu_probe(struct platform_device *pdev)
>  	pm_runtime_enable(dev);
>  
>  	data->sysmmu = dev;
> +
>  	data->clk = devm_clk_get(dev, "sysmmu");
>  	if (IS_ERR(data->clk)) {
>  		dev_info(dev, "No gate clock found!\n");
>  		data->clk = NULL;
>  	}
>  
> +	ret = clk_prepare(data->clk);
> +	if (ret) {
> +		dev_err(dev, "Failed to prepare clk\n");
> +		return ret;
> +	}
> +
> +	data->clk_master = devm_clk_get(dev, "master");
> +	if (IS_ERR(data->clk_master))
> +		data->clk_master = NULL;
> +
> +	ret = clk_prepare(data->clk_master);
> +	if (ret) {
> +		clk_unprepare(data->clk);
> +		dev_err(dev, "Failed to prepare master's clk\n");
> +		return ret;
> +	}
> +
> +	data->runtime_active = !pm_runtime_enabled(dev);
> +
>  	rwlock_init(&data->lock);
>  	INIT_LIST_HEAD(&data->node);
>  
> @@ -625,6 +744,34 @@ 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", },
> @@ -637,6 +784,7 @@ 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),
>  	}
>  };
> @@ -689,7 +837,7 @@ err_pgtable:
>  static void exynos_iommu_domain_destroy(struct iommu_domain *domain)
>  {
>  	struct exynos_iommu_domain *priv = domain->priv;
> -	struct sysmmu_drvdata *data;
> +	struct exynos_iommu_client *client;
>  	unsigned long flags;
>  	int i;
>  
> @@ -697,11 +845,14 @@ static void exynos_iommu_domain_destroy(struct iommu_domain *domain)
>  
>  	spin_lock_irqsave(&priv->lock, flags);
>  
> -	list_for_each_entry(data, &priv->clients, node) {
> -		while (!exynos_sysmmu_disable(data->dev))
> +	list_for_each_entry(client, &priv->clients, node) {
> +		while (!exynos_sysmmu_disable(client->dev))
>  			; /* until System MMU is actually disabled */
>  	}
>  
> +	while (!list_empty(&priv->clients))
> +		list_del_init(priv->clients.next);
> +
>  	spin_unlock_irqrestore(&priv->lock, flags);
>  
>  	for (i = 0; i < NUM_LV1ENTRIES; i++)
> @@ -718,41 +869,26 @@ static void exynos_iommu_domain_destroy(struct iommu_domain *domain)
>  static int exynos_iommu_attach_device(struct iommu_domain *domain,
>  				   struct device *dev)
>  {
> -	struct sysmmu_drvdata *data = dev_get_drvdata(dev->archdata.iommu);
> +	struct exynos_iommu_client *client = dev->archdata.iommu;
>  	struct exynos_iommu_domain *priv = domain->priv;
>  	unsigned long flags;
>  	int ret;
>  
> -	ret = pm_runtime_get_sync(data->sysmmu);
> -	if (ret < 0)
> -		return ret;
> -
> -	ret = 0;
> -
>  	spin_lock_irqsave(&priv->lock, flags);
>  
> -	ret = __exynos_sysmmu_enable(data, __pa(priv->pgtable), domain);
> -
> -	if (ret == 0) {
> -		/* 'data->node' must not be appeared in priv->clients */
> -		BUG_ON(!list_empty(&data->node));
> -		data->dev = dev;
> -		list_add_tail(&data->node, &priv->clients);
> -	}
> +	ret = __exynos_sysmmu_enable(dev, __pa(priv->pgtable), domain);
> +	if (ret == 0)
> +		list_add_tail(&client->node, &priv->clients);
>  
>  	spin_unlock_irqrestore(&priv->lock, flags);
>  
> -	if (ret < 0) {
> +	if (ret < 0)
>  		dev_err(dev, "%s: Failed to attach IOMMU with pgtable %#lx\n",
>  				__func__, __pa(priv->pgtable));
> -		pm_runtime_put(data->sysmmu);
> -	} else if (ret > 0) {
> -		dev_dbg(dev, "%s: IOMMU with pgtable 0x%lx already attached\n",
> -					__func__, __pa(priv->pgtable));
> -	} else {
> -		dev_dbg(dev, "%s: Attached new IOMMU with pgtable 0x%lx\n",
> -					__func__, __pa(priv->pgtable));
> -	}
> +	else
> +		dev_dbg(dev, "%s: Attached IOMMU with pgtable 0x%lx%s\n",
> +					__func__, __pa(priv->pgtable),
> +					(ret == 0) ? "" : ", again");
>  
>  	return ret;
>  }
> @@ -760,39 +896,27 @@ static int exynos_iommu_attach_device(struct iommu_domain *domain,
>  static void exynos_iommu_detach_device(struct iommu_domain *domain,
>  				    struct device *dev)
>  {
> -	struct sysmmu_drvdata *data = dev_get_drvdata(dev->archdata.iommu);
> +	struct exynos_iommu_client *client = NULL;
>  	struct exynos_iommu_domain *priv = domain->priv;
> -	struct list_head *pos;
>  	unsigned long flags;
> -	bool found = false;
>  
>  	spin_lock_irqsave(&priv->lock, flags);
>  
> -	list_for_each(pos, &priv->clients) {
> -		if (list_entry(pos, struct sysmmu_drvdata, node) == data) {
> -			found = true;
> +	list_for_each_entry(client, &priv->clients, node) {
> +		if (client == dev->archdata.iommu) {
> +			if (exynos_sysmmu_disable(dev))
> +				list_del_init(&client->node);
>  			break;
>  		}
>  	}
>  
> -	if (!found)
> -		goto finish;
> +	spin_unlock_irqrestore(&priv->lock, flags);
>  
> -	if (__exynos_sysmmu_disable(data)) {
> +	if (client == dev->archdata.iommu)
>  		dev_dbg(dev, "%s: Detached IOMMU with pgtable %#lx\n",
>  					__func__, __pa(priv->pgtable));
> -		list_del_init(&data->node);
> -
> -	} else {
> -		dev_dbg(dev, "%s: Detaching IOMMU with pgtable %#lx delayed",
> -					__func__, __pa(priv->pgtable));
> -	}
> -
> -finish:
> -	spin_unlock_irqrestore(&priv->lock, flags);
> -
> -	if (found)
> -		pm_runtime_put(data->sysmmu);
> +	else
> +		dev_dbg(dev, "%s: No IOMMU is attached\n", __func__);
>  }
>  
>  static unsigned long *alloc_lv2entry(unsigned long *sent, unsigned long iova,
> @@ -914,7 +1038,7 @@ static size_t exynos_iommu_unmap(struct iommu_domain *domain,
>  					       unsigned long iova, size_t size)
>  {
>  	struct exynos_iommu_domain *priv = domain->priv;
> -	struct sysmmu_drvdata *data;
> +	struct exynos_iommu_client *client;
>  	unsigned long flags;
>  	unsigned long *ent;
>  	size_t err_pgsize;
> @@ -975,8 +1099,8 @@ done:
>  	spin_unlock_irqrestore(&priv->pgtablelock, flags);
>  
>  	spin_lock_irqsave(&priv->lock, flags);
> -	list_for_each_entry(data, &priv->clients, node)
> -		sysmmu_tlb_invalidate_entry(data->dev, iova);
> +	list_for_each_entry(client, &priv->clients, node)
> +		sysmmu_tlb_invalidate_entry(client->dev, iova);
>  	spin_unlock_irqrestore(&priv->lock, flags);
>  
>  	return size;
> @@ -1055,3 +1179,275 @@ static int __init exynos_iommu_init(void)
>  	return ret;
>  }
>  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;
> +	}
> +
> +	if (!ret)
> +		ret = pm_generic_resume(dev);
> +
> +	if (ret) {
> +		int j;
> +
> +		for (j = 0; j < i; j++)
> +			pm_generic_suspend(client->sysmmu[j]);
> +	}
> +
> +	return ret;
> +}
> +#endif
> +
> +#ifdef CONFIG_PM_RUNTIME
> +static void sysmmu_restore_state(struct device *sysmmu)
> +{
> +	struct sysmmu_drvdata *data = dev_get_drvdata(sysmmu);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&data->lock, flags);
> +	data->runtime_active = true;
> +	if (is_sysmmu_active(data))
> +		__sysmmu_enable_nocount(data);
> +	spin_unlock_irqrestore(&data->lock, flags);
> +}
> +
> +static void sysmmu_save_state(struct device *sysmmu)
> +{
> +	struct sysmmu_drvdata *data = dev_get_drvdata(sysmmu);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&data->lock, flags);
> +	if (is_sysmmu_active(data))
> +		__sysmmu_disable_nocount(data);
> +	data->runtime_active = false;
> +	spin_unlock_irqrestore(&data->lock, flags);
> +}
> +
> +static int sysmmu_pm_genpd_save_state(struct device *dev)
> +{
> +	struct exynos_iommu_client *client = dev->archdata.iommu;
> +	int (*cb)(struct device *__dev);
> +	int i;
> +
> +	if (dev->type && dev->type->pm)
> +		cb = dev->type->pm->runtime_suspend;
> +	else if (dev->class && dev->class->pm)
> +		cb = dev->class->pm->runtime_suspend;
> +	else if (dev->bus && dev->bus->pm)
> +		cb = dev->bus->pm->runtime_suspend;
> +	else
> +		cb = NULL;
> +
> +	if (!cb && dev->driver && dev->driver->pm)
> +		cb = dev->driver->pm->runtime_suspend;
> +
> +	if (cb) {
> +		int ret;
> +
> +		ret = cb(dev);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	for (i = 0; i < client->num_sysmmu; i++)
> +		sysmmu_save_state(client->sysmmu[i]);
> +
> +	return 0;
> +}
> +
> +static int sysmmu_pm_genpd_restore_state(struct device *dev)
> +{
> +	struct exynos_iommu_client *client = dev->archdata.iommu;
> +	int (*cb)(struct device *__dev);
> +	int i;
> +
> +	if (dev->type && dev->type->pm)
> +		cb = dev->type->pm->runtime_resume;
> +	else if (dev->class && dev->class->pm)
> +		cb = dev->class->pm->runtime_resume;
> +	else if (dev->bus && dev->bus->pm)
> +		cb = dev->bus->pm->runtime_resume;
> +	else
> +		cb = NULL;
> +
> +	if (!cb && dev->driver && dev->driver->pm)
> +		cb = dev->driver->pm->runtime_resume;
> +
> +	for (i = 0; i < client->num_sysmmu; i++)
> +		sysmmu_restore_state(client->sysmmu[i]);
> +
> +	if (cb) {
> +		int ret;
> +		ret = cb(dev);
> +		if (ret) {
> +			for (i = 0; i < client->num_sysmmu; i++)
> +				sysmmu_save_state(client->sysmmu[i]);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +#endif
> +
> +#ifdef CONFIG_PM_GENERIC_DOMAINS
> +struct gpd_dev_ops sysmmu_devpm_ops = {
> +#ifdef CONFIG_PM_RUNTIME
> +	.save_state = &sysmmu_pm_genpd_save_state,
> +	.restore_state = &sysmmu_pm_genpd_restore_state,
> +#endif
> +#ifdef CONFIG_PM_SLEEP
> +	.suspend = &sysmmu_pm_genpd_suspend,
> +	.resume = &sysmmu_pm_genpd_resume,
> +#endif
> +};
> +#endif /* CONFIG_PM_GENERIC_DOMAINS */
> +
> +static int sysmmu_hook_driver_register(struct notifier_block *nb,
> +					unsigned long val,
> +					void *p)
> +{
> +	struct device *dev = p;
> +
> +	switch (val) {
> +	case BUS_NOTIFY_BIND_DRIVER:
> +	{
> +		int i = 0;
> +		int size = 0;
> +		const __be32 *phandle;
> +		struct exynos_iommu_client *client;
> +
> +		phandle = of_get_property(dev->of_node, "iommu", &size);
> +		if (!phandle)
> +			break;
> +
> +		size = size / sizeof(*phandle); /* number of elements */
> +
> +		client = devm_kzalloc(dev, sizeof(*client) * size, GFP_KERNEL);
> +		if (!client) {
> +			dev_err(dev, "No Memory for exynos_iommu_client\n");
> +			return -ENOMEM;
> +		}
> +
> +		client->num_sysmmu = size;
> +		client->dev = dev;
> +		INIT_LIST_HEAD(&client->node);
> +		spin_lock_init(&client->lock);
> +
> +		for (i = 0; i < size; i++) {
> +			struct device_node *np;
> +			struct platform_device *sysmmu;
> +
> +			/* this always success: see above of_find_property() */
> +			np = of_parse_phandle(dev->of_node, "iommu", i);
> +
> +			sysmmu = of_find_device_by_node(np);
> +			if (!sysmmu) {
> +				dev_err(dev,
> +					"sysmmu node '%s' is not found\n",
> +					np->name);
> +				break;
> +			}
> +
> +			client->sysmmu[i] = &sysmmu->dev;
> +		}
> +
> +		if (i < size) {
> +			while (--i >= 0)
> +				of_node_put(client->sysmmu[i]->of_node);
> +			devm_kfree(dev, client);
> +			return -ENODEV;
> +		}
> +
> +		i = pm_genpd_add_callbacks(dev, &sysmmu_devpm_ops, NULL);
> +		if (i && (i != -ENOSYS)) {
> +			dev_err(dev,
> +				"Failed to register 'dev_pm_ops' for iommu\n");
> +			devm_kfree(dev, client);
> +			return i;
> +		}
> +
> +		dev->archdata.iommu = client;
> +		break;
> +	}
> +	case BUS_NOTIFY_BOUND_DRIVER:
> +	{
> +		struct exynos_iommu_client *client = dev->archdata.iommu;
> +		if (dev->archdata.iommu &&
> +				(!pm_runtime_enabled(dev) ||
> +					 IS_ERR(dev_to_genpd(dev)))) {
> +			int i;
> +			for (i = 0; i < client->num_sysmmu; i++) {
> +				struct sysmmu_drvdata *data;
> +				pm_runtime_disable(client->sysmmu[i]);
> +				data = dev_get_drvdata(client->sysmmu[i]);
> +				if (!data)
> +					continue;
> +				data->runtime_active =
> +					!pm_runtime_enabled(data->sysmmu);
> +				if (data->runtime_active &&
> +						is_sysmmu_active(data))
> +					__sysmmu_enable_nocount(data);
> +			}
> +		}
> +		break;
> +	}
> +	case BUS_NOTIFY_UNBOUND_DRIVER:
> +	{
> +		if (dev->archdata.iommu) {
> +			__pm_genpd_remove_callbacks(dev, false);
> +
> +			devm_kfree(dev, dev->archdata.iommu);
> +
> +			dev->archdata.iommu = NULL;
> +		}
> +		break;
> +	}
> +	} /* switch (val) */
> +
> +	return 0;
> +}
> +
> +static struct notifier_block sysmmu_notifier = {
> +	.notifier_call = &sysmmu_hook_driver_register,
> +};
> +
> +static int __init exynos_iommu_prepare(void)
> +{
> +	return bus_register_notifier(&platform_bus_type, &sysmmu_notifier);
> +}
> +arch_initcall(exynos_iommu_prepare);

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