linux-kernel - [PATCH 4/6] device: add cmdmem support for MMIO address

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Date:   Mon, 30 Mar 2020 14:27:12 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     vkoul@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, hpa@...or.com, bhelgaas@...gle.com,
        gregkh@...uxfoundation.org, arnd@...db.de
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        dmaengine@...r.kernel.org, dan.j.williams@...el.com,
        ashok.raj@...el.com, fenghua.yu@...el.com,
        linux-pci@...r.kernel.org, tony.luck@...el.com, jing.lin@...el.com,
        sanjay.k.kumar@...el.com
Subject: [PATCH 4/6] device: add cmdmem support for MMIO address

With the introduction of ENQCMDS CPU instruction on Intel CPU, a number of
accelerator devices that support accepting data via ENQCMDS will be
arriving. Add devm_cmdmem_remap/unmap() wrappers to remap BAR memory to
specifically denote that these regions are of cmdmem behavior type even
thought they are iomem.

Signed-off-by: Dave Jiang <dave.jiang@...el.com>
---
 include/linux/io.h |    4 ++++
 lib/devres.c       |   36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/linux/io.h b/include/linux/io.h
index b1c44bb4b2d7..2b3356244553 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -79,6 +79,10 @@ void devm_memunmap(struct device *dev, void *addr);
 
 void *__devm_memremap_pages(struct device *dev, struct resource *res);
 
+void __iomem *devm_cmdmem_remap(struct device *dev, resource_size_t offset,
+				 resource_size_t size);
+void devm_cmdmem_unmap(struct device *dev, void __iomem *addr);
+
 #ifdef CONFIG_PCI
 /*
  * The PCI specifications (Rev 3.0, 3.2.5 "Transaction Ordering and
diff --git a/lib/devres.c b/lib/devres.c
index 6ef51f159c54..a14a49087b37 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -218,6 +218,42 @@ void __iomem *devm_of_iomap(struct device *dev, struct device_node *node, int in
 }
 EXPORT_SYMBOL(devm_of_iomap);
 
+/**
+ * devm_cmdmem_remap - Managed wrapper for cmdmem ioremap()
+ * @dev: Generic device to remap IO address for
+ * @offset: Resource address to map
+ * @size: Size of map
+ *
+ * Managed cmdmem ioremap() wrapper.  Map is automatically unmapped on
+ * driver detach.
+ */
+void __iomem *devm_cmdmem_remap(struct device *dev, resource_size_t offset,
+				 resource_size_t size)
+{
+	if (!device_supports_cmdmem(dev))
+		return NULL;
+
+	return devm_ioremap(dev, offset, size);
+}
+EXPORT_SYMBOL(devm_cmdmem_remap);
+
+/**
+ * devm_cmdmem_unmap - Managed wrapper for cmdmem iounmap()
+ * @dev: Generic device to unmap for
+ * @addr: Address to unmap
+ *
+ * Managed cmdmem iounmap().  @addr must have been mapped using
+ * devm_cmdmem_remap*().
+ */
+void devm_cmdmem_unmap(struct device *dev, void __iomem *addr)
+{
+	if (!device_supports_cmdmem(dev))
+		return;
+
+	devm_iounmap(dev, addr);
+}
+EXPORT_SYMBOL(devm_cmdmem_unmap);
+
 #ifdef CONFIG_HAS_IOPORT_MAP
 /*
  * Generic iomap devres