linux-kernel - [RFC PATCH v3 6/6] of: Add plumbing for restricted DMA pool

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Date:   Wed,  6 Jan 2021 11:41:24 +0800
From:   Claire Chang <tientzu@...omium.org>
To:     robh+dt@...nel.org, mpe@...erman.id.au, benh@...nel.crashing.org,
        paulus@...ba.org, joro@...tes.org, will@...nel.org,
        frowand.list@...il.com, konrad.wilk@...cle.com,
        boris.ostrovsky@...cle.com, jgross@...e.com,
        sstabellini@...nel.org, hch@....de, m.szyprowski@...sung.com,
        robin.murphy@....com
Cc:     grant.likely@....com, xypron.glpk@....de, treding@...dia.com,
        mingo@...nel.org, bauerman@...ux.ibm.com, peterz@...radead.org,
        gregkh@...uxfoundation.org, saravanak@...gle.com,
        rafael.j.wysocki@...el.com, heikki.krogerus@...ux.intel.com,
        andriy.shevchenko@...ux.intel.com, rdunlap@...radead.org,
        dan.j.williams@...el.com, bgolaszewski@...libre.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, iommu@...ts.linux-foundation.org,
        xen-devel@...ts.xenproject.org, tfiga@...omium.org,
        drinkcat@...omium.org, Claire Chang <tientzu@...omium.org>
Subject: [RFC PATCH v3 6/6] of: Add plumbing for restricted DMA pool

If a device is not behind an IOMMU, we look up the device node and set
up the restricted DMA when the restricted-dma-pool is presented.

Signed-off-by: Claire Chang <tientzu@...omium.org>
---
 drivers/of/address.c    | 21 +++++++++++++++++++++
 drivers/of/device.c     |  4 ++++
 drivers/of/of_private.h |  5 +++++
 3 files changed, 30 insertions(+)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 73ddf2540f3f..94eca8249854 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -8,6 +8,7 @@
 #include <linux/logic_pio.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
+#include <linux/of_reserved_mem.h>
 #include <linux/pci.h>
 #include <linux/pci_regs.h>
 #include <linux/sizes.h>
@@ -1094,3 +1095,23 @@ bool of_dma_is_coherent(struct device_node *np)
 	return false;
 }
 EXPORT_SYMBOL_GPL(of_dma_is_coherent);
+
+int of_dma_set_restricted_buffer(struct device *dev)
+{
+	struct device_node *node;
+	int count, i;
+
+	if (!dev->of_node)
+		return 0;
+
+	count = of_property_count_elems_of_size(dev->of_node, "memory-region",
+						sizeof(phandle));
+	for (i = 0; i < count; i++) {
+		node = of_parse_phandle(dev->of_node, "memory-region", i);
+		if (of_device_is_compatible(node, "restricted-dma-pool"))
+			return of_reserved_mem_device_init_by_idx(
+				dev, dev->of_node, i);
+	}
+
+	return 0;
+}
diff --git a/drivers/of/device.c b/drivers/of/device.c
index aedfaaafd3e7..e2c7409956ab 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -182,6 +182,10 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
 	arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);
 
 	dev->dma_range_map = map;
+
+	if (!iommu)
+		return of_dma_set_restricted_buffer(dev);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(of_dma_configure_id);
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index d9e6a324de0a..28a2dfa197ba 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -161,12 +161,17 @@ struct bus_dma_region;
 #if defined(CONFIG_OF_ADDRESS) && defined(CONFIG_HAS_DMA)
 int of_dma_get_range(struct device_node *np,
 		const struct bus_dma_region **map);
+int of_dma_set_restricted_buffer(struct device *dev);
 #else
 static inline int of_dma_get_range(struct device_node *np,
 		const struct bus_dma_region **map)
 {
 	return -ENODEV;
 }
+static inline int of_dma_get_restricted_buffer(struct device *dev)
+{
+	return -ENODEV;
+}
 #endif
 
 #endif /* _LINUX_OF_PRIVATE_H */
-- 
2.29.2.729.g45daf8777d-goog