linux-kernel - [PATCH 02/11] PCI: Cleanup pci_rebar_bytes_to

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Message-Id: <20250911075605.5277-3-ilpo.jarvinen@linux.intel.com>
Date: Thu, 11 Sep 2025 10:55:56 +0300
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: linux-pci@...r.kernel.org,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Christian König <christian.koenig@....com>,
	Michał Winiarski <michal.winiarski@...el.com>,
	Alex Deucher <alexander.deucher@....com>,
	amd-gfx@...ts.freedesktop.org,
	David Airlie <airlied@...il.com>,
	dri-devel@...ts.freedesktop.org,
	intel-gfx@...ts.freedesktop.org,
	intel-xe@...ts.freedesktop.org,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	Lucas De Marchi <lucas.demarchi@...el.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Simona Vetter <simona@...ll.ch>,
	Tvrtko Ursulin <tursulin@...ulin.net>,
	?UTF-8?q?Thomas=20Hellstr=C3=B6m?= <thomas.hellstrom@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Cc: linux-doc@...r.kernel.org,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH 02/11] PCI: Cleanup pci_rebar_bytes_to_size() and move into rebar.c

Move pci_rebar_bytes_to_size() from include/linux/pci.h into rebar.c as
it does not look very trivial and is not expected to be performance
critical.

Convert literals to use a newly added PCI_REBAR_MIN_SIZE define.

Also add kernel doc for the function as the function is exported.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---
 drivers/pci/rebar.c | 23 +++++++++++++++++++++++
 include/linux/pci.h | 10 +++-------
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/rebar.c b/drivers/pci/rebar.c
index b87cfa6fb3ef..961bd43be02b 100644
--- a/drivers/pci/rebar.c
+++ b/drivers/pci/rebar.c
@@ -7,11 +7,34 @@
 #include <linux/errno.h>
 #include <linux/export.h>
 #include <linux/ioport.h>
+#include <linux/log2.h>
 #include <linux/pci.h>
+#include <linux/sizes.h>
 #include <linux/types.h>
 
 #include "pci.h"
 
+#define PCI_REBAR_MIN_SIZE	((resource_size_t)SZ_1M)
+
+/**
+ * pci_rebar_bytes_to_size - Convert size in bytes to PCI BAR Size
+ * @bytes: size in bytes
+ *
+ * Convert bytes to BAR Size in Resizable BAR Capability (PCIe r6.2,
+ * sec. 7.8.6.3).
+ *
+ * Return: BAR Size as defined in the PCIe spec (0=1MB, bit 31=128TB).
+ */
+int pci_rebar_bytes_to_size(u64 bytes)
+{
+	int rebar_minsize = ilog2(PCI_REBAR_MIN_SIZE);
+
+	bytes = roundup_pow_of_two(bytes);
+
+	return max(ilog2(bytes), rebar_minsize) - rebar_minsize;
+}
+EXPORT_SYMBOL_GPL(pci_rebar_bytes_to_size);
+
 void pci_rebar_init(struct pci_dev *pdev)
 {
 	pdev->rebar_cap = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_REBAR);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 59876de13860..894e9020b07d 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1418,16 +1418,12 @@ void pcibios_reset_secondary_bus(struct pci_dev *dev);
 void pci_update_resource(struct pci_dev *dev, int resno);
 int __must_check pci_assign_resource(struct pci_dev *dev, int i);
 void pci_release_resource(struct pci_dev *dev, int resno);
-static inline int pci_rebar_bytes_to_size(u64 bytes)
-{
-	bytes = roundup_pow_of_two(bytes);
-
-	/* Return BAR size as defined in the resizable BAR specification */
-	return max(ilog2(bytes), 20) - 20;
-}
 
+/* Resizable BAR related routines */
+int pci_rebar_bytes_to_size(u64 bytes);
 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);
 bool pci_device_is_present(struct pci_dev *pdev);
 void pci_ignore_hotplug(struct pci_dev *dev);
-- 
2.39.5