Implement pmap_change_attr() for PowerPC (Book-E only for now)

Summary:
Some drivers need special memory requirements.  X86 solves this with a
pmap_change_attr() API, which DRM uses for changing the mapping of the GART and
other memory regions.  Implement the same function for PowerPC.  AIM currently
does not need this, but will in the future for DRM, so a default is added for
that, for business as usual.  Book-E has some drivers coming down that do
require non-default memory coherency.  In this case, the Datapath Acceleration
Architecture (DPAA) based ethernet controller has 2 regions for the buffer
portals: cache-inhibited, and cache-enabled.  By default, device memory is
cache-inhibited.  If the cache-enabled memory regions are mapped
cache-inhibited, an alignment exception is thrown on access.

Test Plan:
Tested with a new driver to be added after this (DPAA dTSEC ethernet driver).
No alignment exceptions thrown, driver works as expected with this.

Reviewed By:	nwhitehorn
Sponsored by:	Alex Perez/Inertial Computing
Differential Revision: https://reviews.freebsd.org/D5471

2 files changed, 30 insertions, 0 deletions

diff --git a/sys/powerpc/powerpc/mmu_if.m b/sys/powerpc/powerpc/mmu_if.m
index 6c41c74..ce05bd4 100644
--- a/sys/powerpc/powerpc/mmu_if.m
+++ b/sys/powerpc/powerpc/mmu_if.m
@@ -124,6 +124,12 @@ CODE {
 	{
 		return;
 	}
+
+	static int mmu_null_change_attr(mmu_t mmu, vm_offset_t va,
+	    vm_size_t sz, vm_memattr_t mode)
+	{
+		return (0);
+	}
 };
 
 
@@ -956,3 +962,20 @@ METHOD void quick_remove_page {
 	vm_offset_t	_va;
 };
 
+/**
+ * @brief Change the specified virtual address range's memory type.
+ *
+ * @param _va		The virtual base address to change
+ *
+ * @param _sz		Size of the region to change
+ *
+ * @param _mode		New mode to set on the VA range
+ *
+ * @retval error	0 on success, EINVAL or ENOMEM on error.
+ */
+METHOD int change_attr {
+	mmu_t		_mmu;
+	vm_offset_t	_va;
+	vm_size_t	_sz;
+	vm_memattr_t	_mode;
+} DEFAULT mmu_null_change_attr;
diff --git a/sys/powerpc/powerpc/pmap_dispatch.c b/sys/powerpc/powerpc/pmap_dispatch.c
index 2082ba0..e7b6d76 100644
--- a/sys/powerpc/powerpc/pmap_dispatch.c
+++ b/sys/powerpc/powerpc/pmap_dispatch.c
@@ -564,6 +564,13 @@ pmap_quick_remove_page(vm_offset_t addr)
 	MMU_QUICK_REMOVE_PAGE(mmu_obj, addr);
 }
 
+int
+pmap_change_attr(vm_offset_t addr, vm_size_t size, vm_memattr_t mode)
+{
+	CTR4(KTR_PMAP, "%s(%#x, %#zx, %d)", __func__, addr, size, mode);
+	return (MMU_CHANGE_ATTR(mmu_obj, addr, size, mode));
+}
+
 /*
  * MMU install routines. Highest priority wins, equal priority also
  * overrides allowing last-set to win.