** System MMU optional properties:
+- dma-coherent : Present if page table walks made by the SMMU are
+ cache coherent with the CPU.
+
+ NOTE: this only applies to the SMMU itself, not
+ masters connected upstream of the SMMU.
+
- calxeda,smmu-secure-config-access : Enable proper handling of buggy
implementations that always use secure access to
SMMU configuration registers. In this case non-secure
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/of.h>
+#include <linux/of_address.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
unsigned long size;
void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
u32 id;
+ bool cttw_dt, cttw_reg;
dev_notice(smmu->dev, "probing hardware configuration...\n");
dev_notice(smmu->dev, "SMMUv%d with:\n", smmu->version);
dev_notice(smmu->dev, "\taddress translation ops\n");
}
- if (id & ID0_CTTW) {
+ /*
+ * In order for DMA API calls to work properly, we must defer to what
+ * the DT says about coherency, regardless of what the hardware claims.
+ * Fortunately, this also opens up a workaround for systems where the
+ * ID register value has ended up configured incorrectly.
+ */
+ cttw_dt = of_dma_is_coherent(smmu->dev->of_node);
+ cttw_reg = !!(id & ID0_CTTW);
+ if (cttw_dt)
smmu->features |= ARM_SMMU_FEAT_COHERENT_WALK;
- dev_notice(smmu->dev, "\tcoherent table walk\n");
- }
+ if (cttw_dt || cttw_reg)
+ dev_notice(smmu->dev, "\t%scoherent table walk\n",
+ cttw_dt ? "" : "non-");
+ if (cttw_dt != cttw_reg)
+ dev_notice(smmu->dev,
+ "\t(IDR0.CTTW overridden by dma-coherent property)\n");
if (id & ID0_SMS) {
u32 smr, sid, mask;