iommu/rockchip: Control clocks needed to access the IOMMU

Current code relies on master driver enabling necessary clocks before
IOMMU is accessed, however there are cases when the IOMMU should be
accessed while the master is not running yet, for example allocating
V4L2 videobuf2 buffers, which is done by the VB2 framework using DMA
mapping API and doesn't engage the master driver at all.

This patch fixes the problem by letting clocks needed for IOMMU
operation to be listed in Device Tree and making the driver enable them
for the time of accessing the hardware.

Signed-off-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/rockchip-iommu.c

@@ -4,6 +4,7 @@
  * published by the Free Software Foundation.
  */
 
+#include <linux/clk.h>
 #include <linux/compiler.h>
 #include <linux/delay.h>
 #include <linux/device.h>
@@ -87,10 +88,17 @@ struct rk_iommu_domain {
 	struct iommu_domain domain;
 };
 
+/* list of clocks required by IOMMU */
+static const char * const rk_iommu_clocks[] = {
+	"aclk", "iface",
+};
+
 struct rk_iommu {
 	struct device *dev;
 	void __iomem **bases;
 	int num_mmu;
+	struct clk_bulk_data *clocks;
+	int num_clocks;
 	bool reset_disabled;
 	struct iommu_device iommu;
 	struct list_head node; /* entry in rk_iommu_domain.iommus */
@@ -506,6 +514,8 @@ static irqreturn_t rk_iommu_irq(int irq, void *dev_id)
 	irqreturn_t ret = IRQ_NONE;
 	int i;
 
+	WARN_ON(clk_bulk_enable(iommu->num_clocks, iommu->clocks));
+
 	for (i = 0; i < iommu->num_mmu; i++) {
 		int_status = rk_iommu_read(iommu->bases[i], RK_MMU_INT_STATUS);
 		if (int_status == 0)
@@ -552,6 +562,8 @@ static irqreturn_t rk_iommu_irq(int irq, void *dev_id)
 		rk_iommu_write(iommu->bases[i], RK_MMU_INT_CLEAR, int_status);
 	}
 
+	clk_bulk_disable(iommu->num_clocks, iommu->clocks);
+
 	return ret;
 }
 
@@ -594,7 +606,9 @@ static void rk_iommu_zap_iova(struct rk_iommu_domain *rk_domain,
 	list_for_each(pos, &rk_domain->iommus) {
 		struct rk_iommu *iommu;
 		iommu = list_entry(pos, struct rk_iommu, node);
+		WARN_ON(clk_bulk_enable(iommu->num_clocks, iommu->clocks));
 		rk_iommu_zap_lines(iommu, iova, size);
+		clk_bulk_disable(iommu->num_clocks, iommu->clocks);
 	}
 	spin_unlock_irqrestore(&rk_domain->iommus_lock, flags);
 }
@@ -823,10 +837,14 @@ static int rk_iommu_attach_device(struct iommu_domain *domain,
 	if (!iommu)
 		return 0;
 
-	ret = rk_iommu_enable_stall(iommu);
+	ret = clk_bulk_enable(iommu->num_clocks, iommu->clocks);
 	if (ret)
 		return ret;
 
+	ret = rk_iommu_enable_stall(iommu);
+	if (ret)
+		goto out_disable_clocks;
+
 	ret = rk_iommu_force_reset(iommu);
 	if (ret)
 		goto out_disable_stall;
@@ -852,6 +870,8 @@ static int rk_iommu_attach_device(struct iommu_domain *domain,
 
 out_disable_stall:
 	rk_iommu_disable_stall(iommu);
+out_disable_clocks:
+	clk_bulk_disable(iommu->num_clocks, iommu->clocks);
 	return ret;
 }
 
@@ -873,6 +893,7 @@ static void rk_iommu_detach_device(struct iommu_domain *domain,
 	spin_unlock_irqrestore(&rk_domain->iommus_lock, flags);
 
 	/* Ignore error while disabling, just keep going */
+	WARN_ON(clk_bulk_enable(iommu->num_clocks, iommu->clocks));
 	rk_iommu_enable_stall(iommu);
 	rk_iommu_disable_paging(iommu);
 	for (i = 0; i < iommu->num_mmu; i++) {
@@ -880,6 +901,7 @@ static void rk_iommu_detach_device(struct iommu_domain *domain,
 		rk_iommu_write(iommu->bases[i], RK_MMU_DTE_ADDR, 0);
 	}
 	rk_iommu_disable_stall(iommu);
+	clk_bulk_disable(iommu->num_clocks, iommu->clocks);
 
 	iommu->domain = NULL;
 
@@ -1172,15 +1194,37 @@ static int rk_iommu_probe(struct platform_device *pdev)
 	iommu->reset_disabled = device_property_read_bool(dev,
 					"rockchip,disable-mmu-reset");
 
-	err = iommu_device_sysfs_add(&iommu->iommu, dev, NULL, dev_name(dev));
+	iommu->num_clocks = ARRAY_SIZE(rk_iommu_clocks);
+	iommu->clocks = devm_kcalloc(iommu->dev, iommu->num_clocks,
+				     sizeof(*iommu->clocks), GFP_KERNEL);
+	if (!iommu->clocks)
+		return -ENOMEM;
+
+	for (i = 0; i < iommu->num_clocks; ++i)
+		iommu->clocks[i].id = rk_iommu_clocks[i];
+
+	err = devm_clk_bulk_get(iommu->dev, iommu->num_clocks, iommu->clocks);
+	if (err)
+		return err;
+
+	err = clk_bulk_prepare(iommu->num_clocks, iommu->clocks);
 	if (err)
 		return err;
 
+	err = iommu_device_sysfs_add(&iommu->iommu, dev, NULL, dev_name(dev));
+	if (err)
+		goto err_unprepare_clocks;
+
 	iommu_device_set_ops(&iommu->iommu, &rk_iommu_ops);
 	err = iommu_device_register(&iommu->iommu);
 	if (err)
-		iommu_device_sysfs_remove(&iommu->iommu);
+		goto err_remove_sysfs;
 
+	return 0;
+err_remove_sysfs:
+	iommu_device_sysfs_remove(&iommu->iommu);
+err_unprepare_clocks:
+	clk_bulk_unprepare(iommu->num_clocks, iommu->clocks);
 	return err;
 }