x86/amd-iommu: Add reset function for command buffers
This patch factors parts of the command buffer
initialization code into a seperate function which can be
used to reset the command buffer later.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index c1b17e9..1752afe 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -435,6 +435,20 @@
}
/*
+ * This function resets the command buffer if the IOMMU stopped fetching
+ * commands from it.
+ */
+void amd_iommu_reset_cmd_buffer(struct amd_iommu *iommu)
+{
+ iommu_feature_disable(iommu, CONTROL_CMDBUF_EN);
+
+ writel(0x00, iommu->mmio_base + MMIO_CMD_HEAD_OFFSET);
+ writel(0x00, iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);
+
+ iommu_feature_enable(iommu, CONTROL_CMDBUF_EN);
+}
+
+/*
* This function writes the command buffer address to the hardware and
* enables it.
*/
@@ -450,11 +464,7 @@
memcpy_toio(iommu->mmio_base + MMIO_CMD_BUF_OFFSET,
&entry, sizeof(entry));
- /* set head and tail to zero manually */
- writel(0x00, iommu->mmio_base + MMIO_CMD_HEAD_OFFSET);
- writel(0x00, iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);
-
- iommu_feature_enable(iommu, CONTROL_CMDBUF_EN);
+ amd_iommu_reset_cmd_buffer(iommu);
}
static void __init free_command_buffer(struct amd_iommu *iommu)