linux-kernel - [PATCH v7 02/13] PCI: Add devres helpers for iomap table

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Message-ID: <20240605081605.18769-4-pstanner@redhat.com>
Date: Wed,  5 Jun 2024 10:15:54 +0200
From: Philipp Stanner <pstanner@...hat.com>
To: Hans de Goede <hdegoede@...hat.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Sam Ravnborg <sam@...nborg.org>,
	dakr@...hat.com
Cc: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org,
	Philipp Stanner <pstanner@...hat.com>
Subject: [PATCH v7 02/13] PCI: Add devres helpers for iomap table

The iomap-table administrated by pcim_iomap_table() has its entries set
and unset at several places throughout devres.c using manual iterations
which are effectively code duplications.

This can be done in a centralized, reusable manner.

Providing these new functions here and using them where (already)
possible will allow for using them in subsequent cleanup steps to
simplify the PCI devres API.

Implement helper functions to add mappings to the table and to remove
them again. Use them where applicable.

Signed-off-by: Philipp Stanner <pstanner@...hat.com>
---
 drivers/pci/devres.c | 77 +++++++++++++++++++++++++++++++++-----------
 1 file changed, 58 insertions(+), 19 deletions(-)

diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
index f13edd4a3873..5fc35a947b58 100644
--- a/drivers/pci/devres.c
+++ b/drivers/pci/devres.c
@@ -297,6 +297,52 @@ void __iomem * const *pcim_iomap_table(struct pci_dev *pdev)
 }
 EXPORT_SYMBOL(pcim_iomap_table);
 
+/*
+ * Fill the legacy mapping-table, so that drivers using the old API
+ * can still get a BAR's mapping address through pcim_iomap_table().
+ */
+static int pcim_add_mapping_to_legacy_table(struct pci_dev *pdev,
+		 void __iomem *mapping, short bar)
+{
+	void __iomem **legacy_iomap_table;
+
+	if (bar >= PCI_STD_NUM_BARS)
+		return -EINVAL;
+
+	legacy_iomap_table = (void __iomem **)pcim_iomap_table(pdev);
+	if (!legacy_iomap_table)
+		return -ENOMEM;
+
+	/* The legacy mechanism doesn't allow for duplicate mappings. */
+	WARN_ON(legacy_iomap_table[bar]);
+
+	legacy_iomap_table[bar] = mapping;
+
+	return 0;
+}
+
+/*
+ * Removes a mapping. The table only contains whole-bar-mappings, so this will
+ * never interfere with ranged mappings.
+ */
+static void pcim_remove_mapping_from_legacy_table(struct pci_dev *pdev,
+		void __iomem *addr)
+{
+	short bar;
+	void __iomem **legacy_iomap_table;
+
+	legacy_iomap_table = (void __iomem **)pcim_iomap_table(pdev);
+	if (!legacy_iomap_table)
+		return;
+
+	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
+		if (legacy_iomap_table[bar] == addr) {
+			legacy_iomap_table[bar] = NULL;
+			return;
+		}
+	}
+}
+
 /**
  * pcim_iomap - Managed pcim_iomap()
  * @pdev: PCI device to iomap for
@@ -308,16 +354,20 @@ EXPORT_SYMBOL(pcim_iomap_table);
  */
 void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen)
 {
-	void __iomem **tbl;
+	void __iomem *mapping;
 
-	BUG_ON(bar >= PCIM_IOMAP_MAX);
-
-	tbl = (void __iomem **)pcim_iomap_table(pdev);
-	if (!tbl || tbl[bar])	/* duplicate mappings not allowed */
+	mapping = pci_iomap(pdev, bar, maxlen);
+	if (!mapping)
 		return NULL;
 
-	tbl[bar] = pci_iomap(pdev, bar, maxlen);
-	return tbl[bar];
+	if (pcim_add_mapping_to_legacy_table(pdev, mapping, bar) != 0)
+		goto err_table;
+
+	return mapping;
+
+err_table:
+	pci_iounmap(pdev, mapping);
+	return NULL;
 }
 EXPORT_SYMBOL(pcim_iomap);
 
@@ -330,20 +380,9 @@ EXPORT_SYMBOL(pcim_iomap);
  */
 void pcim_iounmap(struct pci_dev *pdev, void __iomem *addr)
 {
-	void __iomem **tbl;
-	int i;
-
 	pci_iounmap(pdev, addr);
 
-	tbl = (void __iomem **)pcim_iomap_table(pdev);
-	BUG_ON(!tbl);
-
-	for (i = 0; i < PCIM_IOMAP_MAX; i++)
-		if (tbl[i] == addr) {
-			tbl[i] = NULL;
-			return;
-		}
-	WARN_ON(1);
+	pcim_remove_mapping_from_legacy_table(pdev, addr);
 }
 EXPORT_SYMBOL(pcim_iounmap);
 
-- 
2.45.0