[PATCH v2 10/25] asm-generic/io.h: Add a non-posted variant of ioremap()

Hector Martin
2021-02-15T12:20:51Z

ARM64 currently defaults to posted MMIO (nGnRnE), but some devices
require the use of non-posted MMIO (nGnRE). Introduce a new ioremap()
variant to handle this case. ioremap_np() is aliased to ioremap() by
default on arches that do not implement this variant.

This adds the IORESOURCE_MEM_NONPOSTED flag, which maps to this
variant and marks a given resource as requiring non-posted mappings.
This is implemented in the resource system because it is a SoC-level
requirement, so existing drivers do not need special-case code to pick
this ioremap variant.

Then this is implemented in devres by introducing devm_ioremap_np(),
and making devm_ioremap_resource() automatically select this variant
when the resource has the IORESOURCE_MEM_NONPOSTED flag set.

Signed-off-by: Hector Martin <marcan@marcan.st>
---
include/asm-generic/io.h | 8 +++++++-
include/linux/io.h | 2 ++
include/linux/ioport.h | 1 +
lib/devres.c | 22 ++++++++++++++++++++++
4 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index c6af40ce03be..43e4bb8d633c 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -942,7 +942,9 @@ static inline void *phys_to_virt(unsigned long address)
*
* ioremap_wc() and ioremap_wt() can provide more relaxed caching attributes
* for specific drivers if the architecture choses to implement them. If they
- * are not implemented we fall back to plain ioremap.
+ * are not implemented we fall back to plain ioremap. Conversely, ioremap_np()
+ * can provide stricter non-posted write semantics if the architecture
+ * implements them.
*/
#ifndef CONFIG_MMU
#ifndef ioremap
@@ -980,6 +982,10 @@ static inline void __iomem *ioremap(phys_addr_t addr, size_t size)
#define ioremap_wt ioremap
#endif

+#ifndef ioremap_np
+#define ioremap_np ioremap
+#endif
+
/*
* ioremap_uc is special in that we do require an explicit architecture
* implementation. In general you do not want to use this function in a
diff --git a/include/linux/io.h b/include/linux/io.h
index 8394c56babc2..d718354ed3e1 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -68,6 +68,8 @@ void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
resource_size_t size);
void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
resource_size_t size);
+void __iomem *devm_ioremap_np(struct device *dev, resource_size_t offset,
+ resource_size_t size);
void devm_iounmap(struct device *dev, void __iomem *addr);
int check_signature(const volatile void __iomem *io_addr,
const unsigned char *signature, int length);
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index fe48b7840665..5929a67570ae 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -108,6 +108,7 @@ struct resource {
#define IORESOURCE_MEM_32BIT (3<<3)
#define IORESOURCE_MEM_SHADOWABLE (1<<5) /* dup: IORESOURCE_SHADOWABLE */
#define IORESOURCE_MEM_EXPANSIONROM (1<<6)
+#define IORESOURCE_MEM_NONPOSTED (1<<7)

/* PnP I/O specific bits (IORESOURCE_BITS) */
#define IORESOURCE_IO_16BIT_ADDR (1<<0)
diff --git a/lib/devres.c b/lib/devres.c
index 2a4ff5d64288..4679dbb1bf5f 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -10,6 +10,7 @@ enum devm_ioremap_type {
DEVM_IOREMAP = 0,
DEVM_IOREMAP_UC,
DEVM_IOREMAP_WC,
+ DEVM_IOREMAP_NP,
};

void devm_ioremap_release(struct device *dev, void *res)
@@ -42,6 +43,9 @@ static void __iomem *__devm_ioremap(struct device *dev, resource_size_t offset,
case DEVM_IOREMAP_WC:
addr = ioremap_wc(offset, size);
break;
+ case DEVM_IOREMAP_NP:
+ addr = ioremap_np(offset, size);
+ break;
}

if (addr) {
@@ -98,6 +102,21 @@ void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
}
EXPORT_SYMBOL(devm_ioremap_wc);

+/**
+ * devm_ioremap_np - Managed ioremap_np()
+ * @dev: Generic device to remap IO address for
+ * @offset: Resource address to map
+ * @size: Size of map
+ *
+ * Managed ioremap_np(). Map is automatically unmapped on driver detach.
+ */
+void __iomem *devm_ioremap_np(struct device *dev, resource_size_t offset,
+ resource_size_t size)
+{
+ return __devm_ioremap(dev, offset, size, DEVM_IOREMAP_NP);
+}
+EXPORT_SYMBOL(devm_ioremap_np);
+
/**
* devm_iounmap - Managed iounmap()
* @dev: Generic device to unmap for
@@ -128,6 +147,9 @@ __devm_ioremap_resource(struct device *dev, const struct resource *res,
return IOMEM_ERR_PTR(-EINVAL);
}

+ if (type == DEVM_IOREMAP && res->flags & IORESOURCE_MEM_NONPOSTED)
+ type = DEVM_IOREMAP_NP;
+
size = resource_size(res);

if (res->name)
--
2.30.0