From 0a78ac84e9fe3e91d9b01b1e128ea493c6ebc3f4 Mon Sep 17 00:00:00 2001 From: Ahmad Fatoum Date: Mon, 31 May 2021 09:12:35 +0200 Subject: memory: fuse overlapping memory banks Some ARM subarchitectures read back RAM size from the SDRAM controller and use the info to register memory banks. If an overlapping memory region is already registered, e.g. via device tree /memory, this second registration will fail. This is especially annoying as it can regress after a device tree sync: - Kind soul updates upstream device tree to describe minimal available RAM across hardware variants - barebox PBL has enough info about the board to set up larger RAM size and relocates barebox to the end of the RAM - barebox proper starts with new device tree and is upset to find itself outside of registered memory Account for this by growing the existing bank if a bank to be added happens to overlap it. As a special case, if the existing bank completely contains the new memory bank, the function is a no-op. Signed-off-by: Ahmad Fatoum Link: https://lore.barebox.org/20210531071239.30653-3-a.fatoum@pengutronix.de Signed-off-by: Sascha Hauer --- common/memory.c | 49 +++++++++++++++++++++++++++++++++++++++++++++---- common/resource.c | 22 ++++++++++++++++++++++ 2 files changed, 67 insertions(+), 4 deletions(-) (limited to 'common') diff --git a/common/memory.c b/common/memory.c index 612ed87168..95995bb6e3 100644 --- a/common/memory.c +++ b/common/memory.c @@ -111,15 +111,56 @@ void *sbrk(ptrdiff_t increment) LIST_HEAD(memory_banks); +static int barebox_grow_memory_bank(struct memory_bank *bank, const char *name, + const struct resource *newres) +{ + struct resource *res; + resource_size_t bank_end = bank->res->end; + + if (newres->start < bank->start) { + res = request_iomem_region(name, newres->start, bank->start - 1); + if (IS_ERR(res)) + return PTR_ERR(res); + __merge_regions(name, bank->res, res); + } + + if (bank_end < newres->end) { + res = request_iomem_region(name, bank_end + 1, newres->end); + if (IS_ERR(res)) + return PTR_ERR(res); + __merge_regions(name, bank->res, res); + } + + bank->start = newres->start; + bank->size = resource_size(bank->res); + + return 0; +} + int barebox_add_memory_bank(const char *name, resource_size_t start, resource_size_t size) { - struct memory_bank *bank = xzalloc(sizeof(*bank)); + struct memory_bank *bank; + struct resource *res; + struct resource newres = { + .start = start, + .end = start + size - 1, + }; + + for_each_memory_bank(bank) { + if (resource_contains(bank->res, &newres)) + return 0; + if (resource_contains(&newres, bank->res)) + return barebox_grow_memory_bank(bank, name, &newres); + } + + res = request_iomem_region(name, start, start + size - 1); + if (IS_ERR(res)) + return PTR_ERR(res); - bank->res = request_iomem_region(name, start, start + size - 1); - if (IS_ERR(bank->res)) - return PTR_ERR(bank->res); + bank = xzalloc(sizeof(*bank)); + bank->res = res; bank->start = start; bank->size = size; diff --git a/common/resource.c b/common/resource.c index ff4318a0d7..f96cb94b50 100644 --- a/common/resource.c +++ b/common/resource.c @@ -102,6 +102,28 @@ int release_region(struct resource *res) return 0; } + +/* + * merge two adjacent sibling regions. + */ +int __merge_regions(const char *name, + struct resource *resa, struct resource *resb) +{ + if (!resource_adjacent(resa, resb)) + return -EINVAL; + + if (resa->start < resb->start) + resa->end = resb->end; + else + resa->start = resb->start; + + free((char *)resa->name); + resa->name = xstrdup(name); + release_region(resb); + + return 0; +} + /* The root resource for the whole memory-mapped io space */ struct resource iomem_resource = { .start = 0, -- cgit v1.2.3