Commit 89897f73 authored by Hector Martin's avatar Hector Martin
Browse files

of/address: Add infrastructure to declare MMIO as non-posted 



This implements the 'nonposted-mmio' boolean property. Placing this
property in a bus marks all direct child devices as requiring
non-posted MMIO mappings. If no such property is found, the default
is posted MMIO.

of_mmio_is_nonposted() performs this check to determine if a given
device has requested non-posted MMIO.

of_address_to_resource() uses this to set the IORESOURCE_MEM_NONPOSTED
flag on resources that require non-posted MMIO.

of_iomap() and of_io_request_and_map() then use this flag to pick the
correct ioremap() variant.

This mechanism is currently restricted to builds that support Apple ARM
platforms, as an optimization.

Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Reviewed-by: default avatarRob Herring <robh@kernel.org>
Signed-off-by: default avatarHector Martin <marcan@marcan.st>
parent b10eb2d5

drivers/of/address.c

+41 −2
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ static struct of_bus *of_match_bus(struct device_node *np); 
static int __of_address_to_resource(struct device_node *dev,

		const __be32 *addrp, u64 size, unsigned int flags,

		const char *name, struct resource *r);

static bool of_mmio_is_nonposted(struct device_node *np);



/* Debug utility */

#ifdef DEBUG
@@ -847,6 +848,9 @@ static int __of_address_to_resource(struct device_node *dev, 
		return -EINVAL;

	memset(r, 0, sizeof(struct resource));



	if (of_mmio_is_nonposted(dev))

		flags |= IORESOURCE_MEM_NONPOSTED;



	r->start = taddr;

	r->end = taddr + size - 1;

	r->flags = flags;
@@ -896,6 +900,9 @@ void __iomem *of_iomap(struct device_node *np, int index) 
	if (of_address_to_resource(np, index, &res))

		return NULL;



	if (res.flags & IORESOURCE_MEM_NONPOSTED)

		return ioremap_np(res.start, resource_size(&res));

	else

		return ioremap(res.start, resource_size(&res));

}

EXPORT_SYMBOL(of_iomap);
@@ -928,7 +935,11 @@ void __iomem *of_io_request_and_map(struct device_node *np, int index, 
	if (!request_mem_region(res.start, resource_size(&res), name))

		return IOMEM_ERR_PTR(-EBUSY);



	if (res.flags & IORESOURCE_MEM_NONPOSTED)

		mem = ioremap_np(res.start, resource_size(&res));

	else

		mem = ioremap(res.start, resource_size(&res));



	if (!mem) {

		release_mem_region(res.start, resource_size(&res));

		return IOMEM_ERR_PTR(-ENOMEM);
@@ -1094,3 +1105,31 @@ bool of_dma_is_coherent(struct device_node *np) 
	return false;

}

EXPORT_SYMBOL_GPL(of_dma_is_coherent);



/**

 * of_mmio_is_nonposted - Check if device uses non-posted MMIO

 * @np:	device node

 *

 * Returns true if the "nonposted-mmio" property was found for

 * the device's bus.

 *

 * This is currently only enabled on builds that support Apple ARM devices, as

 * an optimization.

 */

static bool of_mmio_is_nonposted(struct device_node *np)

{

	struct device_node *parent;

	bool nonposted;



	if (!IS_ENABLED(CONFIG_ARCH_APPLE))

		return false;



	parent = of_get_parent(np);

	if (!parent)

		return false;



	nonposted = of_property_read_bool(parent, "nonposted-mmio");



	of_node_put(parent);

	return nonposted;

}