[PATCH v4 08/11] PCI: Add pci_rebar_get_max_size()

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

Add pci_rebar_get_max_size() to allow simplifying code that wants to know
the maximum possible size for a Resizable BAR.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
---
 drivers/pci/rebar.c | 23 +++++++++++++++++++++++
 include/linux/pci.h |  1 +
 2 files changed, 24 insertions(+)

diff --git a/drivers/pci/rebar.c b/drivers/pci/rebar.c
index 0e7bf2d380cf..d85d458c7007 100644
--- a/drivers/pci/rebar.c
+++ b/drivers/pci/rebar.c
@@ -5,6 +5,7 @@
 
 #include <linux/bits.h>
 #include <linux/bitfield.h>
+#include <linux/bitops.h>
 #include <linux/errno.h>
 #include <linux/export.h>
 #include <linux/ioport.h>
@@ -142,6 +143,28 @@ bool pci_rebar_size_supported(struct pci_dev *pdev, int bar, int size)
 }
 EXPORT_SYMBOL_GPL(pci_rebar_size_supported);
 
+/**
+ * pci_rebar_get_max_size - get the maximum supported size of a BAR
+ * @pdev: PCI device
+ * @bar: BAR to query
+ *
+ * Get the largest supported size of a resizable BAR as a size.
+ *
+ * Returns: the maximum BAR size as defined in the PCIe spec (0=1MB, 31=128TB),
+ *	     or %-NOENT on error.
+ */
+int pci_rebar_get_max_size(struct pci_dev *pdev, int bar)
+{
+	u32 sizes;
+
+	sizes = pci_rebar_get_possible_sizes(pdev, bar);
+	if (!sizes)
+		return -ENOENT;
+
+	return __fls(sizes);
+}
+EXPORT_SYMBOL_GPL(pci_rebar_get_max_size);
+
 /**
  * pci_rebar_get_current_size - get the current size of a Resizable BAR
  * @pdev: PCI device
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 0ef827cfaf0c..898bc3a4e8e7 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1425,6 +1425,7 @@ int pci_rebar_bytes_to_size(u64 bytes);
 resource_size_t pci_rebar_size_to_bytes(int size);
 u32 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar);
 bool pci_rebar_size_supported(struct pci_dev *pdev, int bar, int size);
+int pci_rebar_get_max_size(struct pci_dev *pdev, int bar);
 int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size,
 				     int exclude_bars);
 
-- 
2.39.5