Current ACPI DMA configuration set-up device DMA capabilities through
kernel defaults that do not take into account platform specific DMA
configurations reported by firmware.

By leveraging the ACPI acpi_dev_get_dma_resources() API, add code
in acpi_dma_configure() to retrieve the DMA regions to correctly
set-up PCI devices DMA parameters.

Rework the ACPI IORT kernel API to make sure they can accommodate
the DMA set-up required by firmware. By making PCI devices DMA set-up
ACPI IORT specific, the kernel is shielded from unwanted regressions
that could be triggered by parsing DMA resources on arches that were
previously ignoring them (ie x86/ia64), leaving kernel behaviour
unchanged on those arches.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieral...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Hanjun Guo <hanjun....@linaro.org>
Cc: Robin Murphy <robin.mur...@arm.com>
Cc: "Rafael J. Wysocki" <r...@rjwysocki.net>
---
 drivers/acpi/arm64/iort.c | 37 +++++++++++++++++++++++++++++++++++--
 drivers/acpi/scan.c       | 12 ++++--------
 include/linux/acpi_iort.h |  5 +++--
 3 files changed, 42 insertions(+), 12 deletions(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index a3215ee..606af87 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -681,12 +681,17 @@ static const struct iommu_ops *iort_iommu_xlate(struct 
device *dev,
 }
 
 /**
- * iort_set_dma_mask - Set-up dma mask for a device.
+ * iort_dma_setup() - Set-up device DMA parameters.
  *
  * @dev: device to configure
+ * @dma_addr: device DMA address result pointer
+ * @size: DMA range size result pointer
  */
-void iort_set_dma_mask(struct device *dev)
+void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
 {
+       u64 mask, dmaaddr = 0, size = 0, offset = 0;
+       int ret, msb;
+
        /*
         * Set default coherent_dma_mask to 32 bit.  Drivers are expected to
         * setup the correct supported mask.
@@ -700,6 +705,34 @@ void iort_set_dma_mask(struct device *dev)
         */
        if (!dev->dma_mask)
                dev->dma_mask = &dev->coherent_dma_mask;
+
+       size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
+
+       if (dev_is_pci(dev)) {
+               ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
+               if (!ret) {
+                       msb = fls64(dmaaddr + size - 1);
+                       /*
+                        * Round-up to the power-of-two mask or set
+                        * the mask to the whole 64-bit address space
+                        * in case the DMA region covers the full
+                        * memory window.
+                        */
+                       mask = msb == 64 ? U64_MAX : (1ULL << msb) - 1;
+                       /*
+                        * Limit coherent and dma mask based on size
+                        * retrieved from firmware.
+                        */
+                       dev->coherent_dma_mask = mask;
+                       *dev->dma_mask = mask;
+               }
+       }
+
+       *dma_addr = dmaaddr;
+       *dma_size = size;
+
+       dev->dma_pfn_offset = PFN_DOWN(offset);
+       dev_dbg(dev, "dma_pfn_offset(%#08llx)\n", offset);
 }
 
 /**
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 842658c..f024996 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1446,20 +1446,16 @@ int acpi_dma_get_range(struct device *dev, u64 
*dma_addr, u64 *offset,
 int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr)
 {
        const struct iommu_ops *iommu;
-       u64 size;
+       u64 dma_addr = 0, size = 0;
 
-       iort_set_dma_mask(dev);
+       iort_dma_setup(dev, &dma_addr, &size);
 
        iommu = iort_iommu_configure(dev);
        if (IS_ERR(iommu) && PTR_ERR(iommu) == -EPROBE_DEFER)
                return -EPROBE_DEFER;
 
-       size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
-       /*
-        * Assume dma valid range starts at 0 and covers the whole
-        * coherent_dma_mask.
-        */
-       arch_setup_dma_ops(dev, 0, size, iommu, attr == DEV_DMA_COHERENT);
+       arch_setup_dma_ops(dev, dma_addr, size,
+                               iommu, attr == DEV_DMA_COHERENT);
 
        return 0;
 }
diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h
index 8379d40..8d3f0bf 100644
--- a/include/linux/acpi_iort.h
+++ b/include/linux/acpi_iort.h
@@ -36,7 +36,7 @@
 void acpi_configure_pmsi_domain(struct device *dev);
 int iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id);
 /* IOMMU interface */
-void iort_set_dma_mask(struct device *dev);
+void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *size);
 const struct iommu_ops *iort_iommu_configure(struct device *dev);
 #else
 static inline void acpi_iort_init(void) { }
@@ -47,7 +47,8 @@ static inline struct irq_domain 
*iort_get_device_domain(struct device *dev,
 { return NULL; }
 static inline void acpi_configure_pmsi_domain(struct device *dev) { }
 /* IOMMU interface */
-static inline void iort_set_dma_mask(struct device *dev) { }
+static inline void iort_dma_setup(struct device *dev, u64 *dma_addr,
+                                 u64 *size) { }
 static inline
 const struct iommu_ops *iort_iommu_configure(struct device *dev)
 { return NULL; }
-- 
1.9.1

Reply via email to