[PATCH 2/4] pci: add BAR bytes->size helper & expose size->bytes helper v2

[Christian König]

From: Darren Salt <devspam at moreofthesa.me.uk>

This is to assist driver modules which do BAR resizing.

v2 (chk): Use ilog2 and make the new funtion extra defensive.
	  Also use the new function on the two existing ocassions.

Signed-off-by: Darren Salt <devspam at moreofthesa.me.uk>
Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c |  3 +--
 drivers/pci/pci.c                          |  2 +-
 drivers/pci/pci.h                          |  4 ----
 include/linux/pci.h                        | 12 ++++++++++++
 4 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index dce0e66b2364..70acd673e3f2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -1089,8 +1089,7 @@ void amdgpu_device_wb_free(struct amdgpu_device *adev, u32 wb)
  */
 int amdgpu_device_resize_fb_bar(struct amdgpu_device *adev)
 {
-	u64 space_needed = roundup_pow_of_two(adev->gmc.real_vram_size);
-	u32 rbar_size = order_base_2(((space_needed >> 20) | 1)) - 1;
+	u32 rbar_size = pci_rebar_bytes_to_size(adev->gmc.real_vram_size);
 	struct pci_bus *root;
 	struct resource *res;
 	unsigned i;
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index ef80ed451415..16216186b51c 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1648,7 +1648,7 @@ static void pci_restore_rebar_state(struct pci_dev *pdev)
 		pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
 		bar_idx = ctrl & PCI_REBAR_CTRL_BAR_IDX;
 		res = pdev->resource + bar_idx;
-		size = ilog2(resource_size(res)) - 20;
+		size = pci_rebar_bytes_to_size(resource_size(res));
 		ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
 		ctrl |= size << PCI_REBAR_CTRL_BAR_SHIFT;
 		pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 640ae7d74fc3..0fa31ff3d4e4 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -610,10 +610,6 @@ int acpi_get_rc_resources(struct device *dev, const char *hid, u16 segment,
 
 int pci_rebar_get_current_size(struct pci_dev *pdev, int bar);
 int pci_rebar_set_size(struct pci_dev *pdev, int bar, int size);
-static inline u64 pci_rebar_size_to_bytes(int size)
-{
-	return 1ULL << (size + 20);
-}
 
 struct device_node;
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 9999040cfad9..673606f871b7 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1226,6 +1226,18 @@ void pci_update_resource(struct pci_dev *dev, int resno);
 int __must_check pci_assign_resource(struct pci_dev *dev, int i);
 int __must_check pci_reassign_resource(struct pci_dev *dev, int i, resource_size_t add_size, resource_size_t align);
 void pci_release_resource(struct pci_dev *dev, int resno);
+
+static __always_inline int pci_rebar_bytes_to_size(u64 bytes)
+{
+	bytes = roundup_pow_of_two(bytes);
+	return max(ilog2(bytes), 20) - 20;
+}
+
+static __always_inline u64 pci_rebar_size_to_bytes(int size)
+{
+	return 1ULL << (size + 20);
+}
+
 u32 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar);
 int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size);
 int pci_select_bars(struct pci_dev *dev, unsigned long flags);
-- 
2.25.1