[05/14] lib: Add I/O map cache implementation

Message ID	1357764194-12677-6-git-send-email-thierry.reding@avionic-design.de (mailing list archive)
State	New, archived
Delegated to:	Bjorn Helgaas
Headers	show Return-Path: <linux-pci-owner@vger.kernel.org> From: Thierry Reding <thierry.reding@avionic-design.de> To: linux-tegra@vger.kernel.org Cc: Grant Likely <grant.likely@secretlab.ca>, Rob Herring <rob.herring@calxeda.com>, Russell King <linux@arm.linux.org.uk>, Stephen Warren <swarren@wwwdotorg.org>, Bjorn Helgaas <bhelgaas@google.com>, Andrew Murray <andrew.murray@arm.com>, Jason Gunthorpe <jgunthorpe@obsidianresearch.com>, Arnd Bergmann <arnd@arndb.de>, Thomas Petazzoni <thomas.petazzoni@free-electrons.com>, devicetree-discuss@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org Subject: [PATCH 05/14] lib: Add I/O map cache implementation Date: Wed, 9 Jan 2013 21:43:05 +0100 Message-Id: <1357764194-12677-6-git-send-email-thierry.reding@avionic-design.de> In-Reply-To: <1357764194-12677-1-git-send-email-thierry.reding@avionic-design.de> References: <1357764194-12677-1-git-send-email-thierry.reding@avionic-design.de> Sender: linux-pci-owner@vger.kernel.org Precedence: bulk

diff --git a/include/linux/io.h b/include/linux/io.h index 069e407..c5d296c 100644 --- a/include/linux/io.h +++ b/include/linux/io.h @@ -76,4 +76,16 @@ void devm_ioremap_release(struct device *dev, void *res); #define arch_has_dev_port() (1) #endif +struct iomap_cache; +struct resource; + +struct iomap_cache *iomap_cache_create(const struct resource *region); +void iomap_cache_free(struct iomap_cache *cache); +void __iomem *iomap_cache_map(struct iomap_cache *cache, unsigned long offset); +void iomap_cache_unmap(struct iomap_cache *cache, void __iomem *addr); + +struct iomap_cache *devm_iomap_cache_create(struct device *dev, + const struct resource *region); +void devm_iomap_cache_free(struct device *dev, struct iomap_cache *cache); + #endif /* _LINUX_IO_H */ diff --git a/lib/ioremap.c b/lib/ioremap.c index 0c9216c..8a13d97 100644 --- a/lib/ioremap.c +++ b/lib/ioremap.c @@ -5,11 +5,16 @@ * * (C) Copyright 1995 1996 Linus Torvalds */ + +#include <linux/device.h> +#include <linux/err.h> #include <linux/vmalloc.h> #include <linux/mm.h> #include <linux/sched.h> #include <linux/io.h> +#include <linux/ioport.h> #include <linux/export.h> +#include <linux/slab.h> #include <asm/cacheflush.h> #include <asm/pgtable.h> @@ -92,3 +97,264 @@ int ioremap_page_range(unsigned long addr, return err; } EXPORT_SYMBOL_GPL(ioremap_page_range); + +/** + * struct iomap_cache_page - page in an I/O map cache + * @region: subregion mapped by the page + * @list: chain in cache list + * @virt: virtual address of mapped region + */ +struct iomap_cache_page { + struct resource *region; + struct list_head list; + void __iomem *virt; +}; + +static struct iomap_cache_page *iomap_cache_page_create(void) +{ + struct iomap_cache_page *page; + + page = kzalloc(sizeof(*page), GFP_KERNEL); + if (!page) + return NULL; + + INIT_LIST_HEAD(&page->list); + + return page; +} + +static void iomap_cache_page_unmap(struct iomap_cache_page *page) +{ + release_resource(page->region); + page->region = NULL; + + iounmap(page->virt); + page->virt = NULL; +} + +static void iomap_cache_page_free(struct iomap_cache_page *page) +{ + iomap_cache_page_unmap(page); + list_del(&page->list); + kfree(page); +} + +/** + * struct iomap_cache - cache of I/O mapped pages + * @region: region mapped by the cache + * @pages: list of pages in the cache + * @num_pages: number of pages in the cache + * @max_pages: maximum number of pages that the cache can map simultaneously + */ +struct iomap_cache { + struct resource region; + struct list_head pages; + unsigned int num_pages; + unsigned int max_pages; +}; + +/** + * iomap_cache_create() - create an I/O map cache + * @region: memory region to map + * + * Returns a new I/O map cache that can be used to map the given region on a + * page by page basis. On failure, a negative error code is returned. + */ +struct iomap_cache *iomap_cache_create(const struct resource *region) +{ + struct iomap_cache *cache; + + cache = kzalloc(sizeof(*cache), GFP_KERNEL); + if (!cache) + return ERR_PTR(-ENOMEM); + + memcpy(&cache->region, region, sizeof(*region)); + INIT_LIST_HEAD(&cache->pages); + cache->num_pages = 0; + cache->max_pages = 1; + + return cache; +} + +/** + * iomap_cache_free() - free an I/O map cache + * @cache: I/O map cache + */ +void iomap_cache_free(struct iomap_cache *cache) +{ + struct iomap_cache_page *page, *tmp; + + if (!cache) + return; + + list_for_each_entry_safe(page, tmp, &cache->pages, list) + iomap_cache_page_free(page); + + kfree(cache); +} + +/** + * iomap_cache_map() - map a given offset in the cache's region + * @cache: I/O map cache + * @offset: offset into the cache's region of the address to map + * + * Returns the virtual address of mapped offset into the cache's region or + * NULL if the offset is outside of the region or if not enough memory is + * available to map the page. + */ +void __iomem *iomap_cache_map(struct iomap_cache *cache, unsigned long offset) +{ + struct iomap_cache_page *page; + struct resource *region; + unsigned long phys; + + if (!cache || offset >= resource_size(&cache->region)) + return NULL; + + phys = cache->region.start + (offset & PAGE_MASK); + + list_for_each_entry(page, &cache->pages, list) { + resource_size_t start, end; + + if (!page->region || !page->virt) + continue; + + start = page->region->start - cache->region.start; + end = page->region->end - cache->region.start; + + /* address is within an already mapped page */ + if (offset >= start && offset <= end) { + /* move page to end of the LRU list */ + list_del_init(&page->list); + list_add_tail(&page->list, &cache->pages); + goto out; + } + } + + /* find an unmapped page */ + list_for_each_entry(page, &cache->pages, list) { + if (!page->region || !page->virt) { + list_del_init(&page->list); + break; + } + } + + /* no unmapped page found */ + if (&page->list == &cache->pages) { + /* add a new page if more space is available */ + if (cache->num_pages < cache->max_pages) { + page = iomap_cache_page_create(); + if (!page) + return NULL; + + cache->num_pages++; + } else { + /* + * If all pages are in use and there's no space left + * for a new one, evict the first page in the list. + */ + page = list_first_entry(&cache->pages, + struct iomap_cache_page, + list); + iomap_cache_page_unmap(page); + list_del_init(&page->list); + } + } + + /* insert page at the end of the LRU list */ + list_add_tail(&page->list, &cache->pages); + + region = __request_region(&cache->region, phys, PAGE_SIZE, NULL, + cache->region.flags); + if (!region) + return NULL; + + page->virt = ioremap(region->start, resource_size(region)); + if (!page->virt) { + release_resource(region); + return NULL; + } + + page->region = region; + +out: + return page->virt + (offset & ~PAGE_MASK); +} + +/** + * iomap_cache_unmap() - remove a mapping from the cache + * @cache: I/O map cache + * @addr: virtual address of the mapping to remove + */ +void iomap_cache_unmap(struct iomap_cache *cache, void __iomem *addr) +{ + struct iomap_cache_page *page; + + if (!cache) + return; + + list_for_each_entry(page, &cache->pages, list) { + if (page->virt == addr) { + iomap_cache_page_unmap(page); + break; + } + } +} + +static void devm_iomap_cache_release(struct device *dev, void *res) +{ + iomap_cache_free(*(struct iomap_cache **)res); +} + +static int devm_iomap_cache_match(struct device *dev, void *res, void *data) +{ + struct iomap_cache **p = res; + + if (WARN_ON(!p || !*p)) + return 0; + + return *p == data; +} + +/** + * devm_iomap_cache_create() - create an I/O map cache + * @dev: device to attach this I/O map cache to + * @region: memory region to map + * + * Returns a new I/O map cache that can be used to map the given region on a + * page by page basis. On failure, a negative error code is returned. + * + * This function is a device-managed version of iomap_cache_create() which + * will automatically be freed when the device disappears. + */ +struct iomap_cache *devm_iomap_cache_create(struct device *dev, + const struct resource *region) +{ + struct iomap_cache **ptr, *cache; + + ptr = devres_alloc(devm_iomap_cache_release, sizeof(**ptr), GFP_KERNEL); + if (!ptr) + return ERR_PTR(-ENOMEM); + + cache = iomap_cache_create(region); + if (IS_ERR(cache)) { + devres_free(ptr); + return cache; + } + + *ptr = cache; + devres_add(dev, ptr); + + return cache; +} + +/** + * devm_iomap_cache_free() - free an I/O map cache + * @dev: device that this I/O map cached was attached to + * @cache: I/O map cache + */ +void devm_iomap_cache_free(struct device *dev, struct iomap_cache *cache) +{ + WARN_ON(devres_release(dev, devm_iomap_cache_release, + devm_iomap_cache_match, cache)); +}

[05/14] lib: Add I/O map cache implementation

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