/* SPDX-License-Identifier: GPL-2.0-only */ #include #include #include #include /** * Round a number up to an alignment. * * @param val The starting value. * @param pow Alignment as a power of two. * @return Rounded up number. */ static resource_t round(resource_t val, unsigned long pow) { return ALIGN_UP(val, POWER_OF_2(pow)); } static const char *resource2str(const struct resource *res) { if (res->flags & IORESOURCE_IO) return "io"; if (res->flags & IORESOURCE_PREFETCH) return "prefmem"; if (res->flags & IORESOURCE_MEM) return "mem"; return "undefined"; } static bool dev_has_children(const struct device *dev) { const struct bus *bus = dev->link_list; return bus && bus->children; } #define res_printk(depth, str, ...) printk(BIOS_DEBUG, "%*c"str, depth, ' ', __VA_ARGS__) /* * During pass 1, once all the requirements for downstream devices of a bridge are gathered, * this function calculates the overall resource requirement for the bridge. It starts by * picking the largest resource requirement downstream for the given resource type and works by * adding requirements in descending order. * * Additionally, it takes alignment and limits of the downstream devices into consideration and * ensures that they get propagated to the bridge resource. This is required to guarantee that * the upstream bridge/domain honors the limit and alignment requirements for this bridge based * on the tightest constraints downstream. */ static void update_bridge_resource(const struct device *bridge, struct resource *bridge_res, unsigned long type_match, int print_depth) { const struct device *child; struct resource *child_res; resource_t base; bool first_child_res = true; const unsigned long type_mask = IORESOURCE_TYPE_MASK | IORESOURCE_PREFETCH; struct bus *bus = bridge->link_list; child_res = NULL; /* * `base` keeps track of where the next allocation for child resource can take place * from within the bridge resource window. Since the bridge resource window allocation * is not performed yet, it can start at 0. Base gets updated every time a resource * requirement is accounted for in the loop below. After scanning all these resources, * base will indicate the total size requirement for the current bridge resource * window. */ base = 0; res_printk(print_depth, "%s %s: size: %llx align: %d gran: %d limit: %llx\n", dev_path(bridge), resource2str(bridge_res), bridge_res->size, bridge_res->align, bridge_res->gran, bridge_res->limit); while ((child = largest_resource(bus, &child_res, type_mask, type_match))) { /* Size 0 resources can be skipped. */ if (!child_res->size) continue; /* * Propagate the resource alignment to the bridge resource if this is the first * child resource with non-zero size being considered. For all other children * resources, alignment is taken care of by updating the base to round up as per * the child resource alignment. It is guaranteed that pass 2 follows the exact * same method of picking the resource for allocation using * largest_resource(). Thus, as long as the alignment for first child resource * is propagated up to the bridge resource, it can be guaranteed that the * alignment for all resources is appropriately met. */ if (first_child_res && (child_res->align > bridge_res->align)) bridge_res->align = child_res->align; first_child_res = false; /* * Propagate the resource limit to the bridge resource only if child resource * limit is non-zero. If a downstream device has stricter requirements * w.r.t. limits for any resource, that constraint needs to be propagated back * up to the downstream bridges of the domain. This guarantees that the resource * allocation which starts at the domain level takes into account all these * constraints thus working on a global view. */ if (child_res->limit && (child_res->limit < bridge_res->limit)) bridge_res->limit = child_res->limit; /* * Propagate the downstream resource request to allocate above 4G boundary to * upstream bridge resource. This ensures that during pass 2, the resource * allocator at domain level has a global view of all the downstream device * requirements and thus address space is allocated as per updated flags in the * bridge resource. * * Since the bridge resource is a single window, all the downstream resources of * this bridge resource will be allocated space above 4G boundary. */ if (child_res->flags & IORESOURCE_ABOVE_4G) bridge_res->flags |= IORESOURCE_ABOVE_4G; /* * Alignment value of 0 means that the child resource has no alignment * requirements and so the base value remains unchanged here. */ base = round(base, child_res->align); res_printk(print_depth + 1, "%s %02lx * [0x%llx - 0x%llx] %s\n", dev_path(child), child_res->index, base, base + child_res->size - 1, resource2str(child_res)); base += child_res->size; } /* * After all downstream device resources are scanned, `base` represents the total size * requirement for the current bridge resource window. This size needs to be rounded up * to the granularity requirement of the bridge to ensure that the upstream * bridge/domain allocates big enough window. */ bridge_res->size = round(base, bridge_res->gran); res_printk(print_depth, "%s %s: size: %llx align: %d gran: %d limit: %llx done\n", dev_path(bridge), resource2str(bridge_res), bridge_res->size, bridge_res->align, bridge_res->gran, bridge_res->limit); } /* * During pass 1, resource allocator at bridge level gathers requirements from downstream * devices and updates its own resource windows for the provided resource type. */ static void compute_bridge_resources(const struct device *bridge, unsigned long type_match, int print_depth) { const struct device *child; struct resource *res; struct bus *bus = bridge->link_list; const unsigned long type_mask = IORESOURCE_TYPE_MASK | IORESOURCE_PREFETCH; for (res = bridge->resource_list; res; res = res->next) { if (!(res->flags & IORESOURCE_BRIDGE)) continue; if ((res->flags & type_mask) != type_match) continue; /* * Ensure that the resource requirements for all downstream bridges are * gathered before updating the window for current bridge resource. */ for (child = bus->children; child; child = child->sibling) { if (!dev_has_children(child)) continue; compute_bridge_resources(child, type_match, print_depth + 1); } /* * Update the window for current bridge resource now that all downstream * requirements are gathered. */ update_bridge_resource(bridge, res, type_match, print_depth); } } /* * During pass 1, resource allocator walks down the entire sub-tree of a domain. It gathers * resource requirements for every downstream bridge by looking at the resource requests of its * children. Thus, the requirement gathering begins at the leaf devices and is propagated back * up to the downstream bridges of the domain. * * At domain level, it identifies every downstream bridge and walks down that bridge to gather * requirements for each resource type i.e. i/o, mem and prefmem. Since bridges have separate * windows for mem and prefmem, requirements for each need to be collected separately. * * Domain resource windows are fixed ranges and hence requirement gathering does not result in * any changes to these fixed ranges. */ static void compute_domain_resources(const struct device *domain) { const struct device *child; const int print_depth = 1; if (domain->link_list == NULL) return; for (child = domain->link_list->children; child; child = child->sibling) { /* Skip if this is not a bridge or has no children under it. */ if (!dev_has_children(child)) continue; compute_bridge_resources(child, IORESOURCE_IO, print_depth); compute_bridge_resources(child, IORESOURCE_MEM, print_depth); compute_bridge_resources(child, IORESOURCE_MEM | IORESOURCE_PREFETCH, print_depth); } } static unsigned char get_alignment_by_resource_type(const struct resource *res) { if (res->flags & IORESOURCE_MEM) return 12; /* Page-aligned --> log2(4KiB) */ else if (res->flags & IORESOURCE_IO) return 0; /* No special alignment required --> log2(1) */ die("Unexpected resource type: flags(%d)!\n", res->flags); } /* * If the resource is NULL or if the resource is not assigned, then it cannot be used for * allocation for downstream devices. */ static bool is_resource_invalid(const struct resource *res) { return (res == NULL) || !(res->flags & IORESOURCE_ASSIGNED); } static void initialize_domain_io_resource_memranges(struct memranges *ranges, const struct resource *res, unsigned long memrange_type) { memranges_insert(ranges, res->base, res->limit - res->base + 1, memrange_type); } static void initialize_domain_mem_resource_memranges(struct memranges *ranges, const struct resource *res, unsigned long memrange_type) { resource_t res_base; resource_t res_limit; const resource_t limit_4g = 0xffffffff; res_base = res->base; res_limit = res->limit; /* * Split the resource into two separate ranges if it crosses the 4G boundary. Memrange * type is set differently to ensure that memrange does not merge these two ranges. For * the range above 4G boundary, given memrange type is ORed with IORESOURCE_ABOVE_4G. */ if (res_base <= limit_4g) { resource_t range_limit; /* Clip the resource limit at 4G boundary if necessary. */ range_limit = MIN(res_limit, limit_4g); memranges_insert(ranges, res_base, range_limit - res_base + 1, memrange_type); /* * If the resource lies completely below the 4G boundary, nothing more needs to * be done. */ if (res_limit <= limit_4g) return; /* * If the resource window crosses the 4G boundary, then update res_base to add * another entry for the range above the boundary. */ res_base = limit_4g + 1; } if (res_base > res_limit) return; /* * If resource lies completely above the 4G boundary or if the resource was clipped to * add two separate ranges, the range above 4G boundary has the resource flag * IORESOURCE_ABOVE_4G set. This allows domain to handle any downstream requests for * resource allocation above 4G differently. */ memranges_insert(ranges, res_base, res_limit - res_base + 1, memrange_type | IORESOURCE_ABOVE_4G); } /* * This function initializes memranges for domain device. If the resource crosses 4G boundary, * then this function splits it into two ranges -- one for the window below 4G and the other for * the window above 4G. The latter range has IORESOURCE_ABOVE_4G flag set to satisfy resource * requests from downstream devices for allocations above 4G. */ static void initialize_domain_memranges(struct memranges *ranges, const struct resource *res, unsigned long memrange_type) { unsigned char align = get_alignment_by_resource_type(res); memranges_init_empty_with_alignment(ranges, NULL, 0, align); if (is_resource_invalid(res)) return; if (res->flags & IORESOURCE_IO) initialize_domain_io_resource_memranges(ranges, res, memrange_type); else initialize_domain_mem_resource_memranges(ranges, res, memrange_type); } /* * This function initializes memranges for bridge device. Unlike domain, bridge does not need to * care about resource window crossing 4G boundary. This is handled by the resource allocator at * domain level to ensure that all downstream bridges are allocated space either above or below * 4G boundary as per the state of IORESOURCE_ABOVE_4G for the respective bridge resource. * * So, this function creates a single range of the entire resource window available for the * bridge resource. Thus all downstream resources of the bridge for the given resource type get * allocated space from the same window. If there is any downstream resource of the bridge which * requests allocation above 4G, then all other downstream resources of the same type under the * bridge get allocated above 4G. */ static void initialize_bridge_memranges(struct memranges *ranges, const struct resource *res, unsigned long memrange_type) { unsigned char align = get_alignment_by_resource_type(res); memranges_init_empty_with_alignment(ranges, NULL, 0, align); if (is_resource_invalid(res)) return; memranges_insert(ranges, res->base, res->limit - res->base + 1, memrange_type); } static void print_resource_ranges(const struct device *dev, const struct memranges *ranges) { const struct range_entry *r; printk(BIOS_INFO, " %s: Resource ranges:\n", dev_path(dev)); if (memranges_is_empty(ranges)) printk(BIOS_INFO, " * EMPTY!!\n"); memranges_each_entry(r, ranges) { printk(BIOS_INFO, " * Base: %llx, Size: %llx, Tag: %lx\n", range_entry_base(r), range_entry_size(r), range_entry_tag(r)); } } /* * This is where the actual allocation of resources happens during pass 2. Given the list of * memory ranges corresponding to the resource of given type, it finds the biggest unallocated * resource using the type mask on the downstream bus. This continues in a descending * order until all resources of given type are allocated address space within the current * resource window. */ static void allocate_child_resources(struct bus *bus, struct memranges *ranges, unsigned long type_mask, unsigned long type_match) { struct resource *resource = NULL; const struct device *dev; while ((dev = largest_resource(bus, &resource, type_mask, type_match))) { if (!resource->size) continue; if (memranges_steal(ranges, resource->limit, resource->size, resource->align, type_match, &resource->base) == false) { printk(BIOS_ERR, " ERROR: Resource didn't fit!!! "); printk(BIOS_DEBUG, " %s %02lx * size: 0x%llx limit: %llx %s\n", dev_path(dev), resource->index, resource->size, resource->limit, resource2str(resource)); continue; } resource->limit = resource->base + resource->size - 1; resource->flags |= IORESOURCE_ASSIGNED; printk(BIOS_DEBUG, " %s %02lx * [0x%llx - 0x%llx] limit: %llx %s\n", dev_path(dev), resource->index, resource->base, resource->size ? resource->base + resource->size - 1 : resource->base, resource->limit, resource2str(resource)); } } static void update_constraints(struct memranges *ranges, const struct device *dev, const struct resource *res) { if (!res->size) return; printk(BIOS_DEBUG, " %s: %s %02lx base %08llx limit %08llx %s (fixed)\n", __func__, dev_path(dev), res->index, res->base, res->base + res->size - 1, resource2str(res)); memranges_create_hole(ranges, res->base, res->size); } /* * Scan the entire tree to identify any fixed resources allocated by any device to * ensure that the address map for domain resources are appropriately updated. * * Domains can typically provide memrange for entire address space. So, this function * punches holes in the address space for all fixed resources that are already * defined. Both IO and normal memory resources are added as fixed. Both need to be * removed from address space where dynamic resource allocations are sourced. */ static void avoid_fixed_resources(struct memranges *ranges, const struct device *dev, unsigned long mask_match) { const struct resource *res; const struct device *child; const struct bus *bus; for (res = dev->resource_list; res != NULL; res = res->next) { if ((res->flags & mask_match) != mask_match) continue; update_constraints(ranges, dev, res); } bus = dev->link_list; if (bus == NULL) return; for (child = bus->children; child != NULL; child = child->sibling) avoid_fixed_resources(ranges, child, mask_match); } static void constrain_domain_resources(const struct device *domain, struct memranges *ranges, unsigned long type) { unsigned long mask_match = type | IORESOURCE_FIXED; if (type == IORESOURCE_IO) { /* * Don't allow allocations in the VGA I/O range. PCI has special cases for * that. */ memranges_create_hole(ranges, 0x3b0, 0x3df - 0x3b0 + 1); /* * Resource allocator no longer supports the legacy behavior where I/O resource * allocation is guaranteed to avoid aliases over legacy PCI expansion card * addresses. */ } avoid_fixed_resources(ranges, domain, mask_match); } /* * This function creates a list of memranges of given type using the resource that is * provided. If the given resource is NULL or if the resource window size is 0, then it creates * an empty list. This results in resource allocation for that resource type failing for all * downstream devices since there is nothing to allocate from. * * In case of domain, it applies additional constraints to ensure that the memranges do not * overlap any of the fixed resources under that domain. Domain typically seems to provide * memrange for entire address space. Thus, it is up to the chipset to add DRAM and all other * windows which cannot be used for resource allocation as fixed resources. */ static void setup_resource_ranges(const struct device *dev, const struct resource *res, unsigned long type, struct memranges *ranges) { printk(BIOS_DEBUG, "%s %s: base: %llx size: %llx align: %d gran: %d limit: %llx\n", dev_path(dev), resource2str(res), res->base, res->size, res->align, res->gran, res->limit); if (dev->path.type == DEVICE_PATH_DOMAIN) { initialize_domain_memranges(ranges, res, type); constrain_domain_resources(dev, ranges, type); } else { initialize_bridge_memranges(ranges, res, type); } print_resource_ranges(dev, ranges); } static void cleanup_resource_ranges(const struct device *dev, struct memranges *ranges, const struct resource *res) { memranges_teardown(ranges); printk(BIOS_DEBUG, "%s %s: base: %llx size: %llx align: %d gran: %d limit: %llx done\n", dev_path(dev), resource2str(res), res->base, res->size, res->align, res->gran, res->limit); } /* * Pass 2 of resource allocator at the bridge level loops through all the resources for the * bridge and generates a list of memory ranges similar to that at the domain level. However, * there is no need to apply any additional constraints since the window allocated to the bridge * is guaranteed to be non-overlapping by the allocator at domain level. * * Allocation at the bridge level works the same as at domain level (starts with the biggest * resource requirement from downstream devices and continues in descending order). One major * difference at the bridge level is that it considers prefmem resources separately from mem * resources. * * Once allocation at the current bridge is complete, resource allocator continues walking down * the downstream bridges until it hits the leaf devices. */ static void allocate_bridge_resources(const struct device *bridge) { struct memranges ranges; const struct resource *res; struct bus *bus = bridge->link_list; unsigned long type_match; struct device *child; const unsigned long type_mask = IORESOURCE_TYPE_MASK | IORESOURCE_PREFETCH; for (res = bridge->resource_list; res; res = res->next) { if (!res->size) continue; if (!(res->flags & IORESOURCE_BRIDGE)) continue; type_match = res->flags & type_mask; setup_resource_ranges(bridge, res, type_match, &ranges); allocate_child_resources(bus, &ranges, type_mask, type_match); cleanup_resource_ranges(bridge, &ranges, res); } for (child = bus->children; child; child = child->sibling) { if (!dev_has_children(child)) continue; allocate_bridge_resources(child); } } static const struct resource *find_domain_resource(const struct device *domain, unsigned long type) { const struct resource *res; for (res = domain->resource_list; res; res = res->next) { if (res->flags & IORESOURCE_FIXED) continue; if ((res->flags & IORESOURCE_TYPE_MASK) == type) return res; } return NULL; } /* * Pass 2 of resource allocator begins at the domain level. Every domain has two types of * resources - io and mem. For each of these resources, this function creates a list of memory * ranges that can be used for downstream resource allocation. This list is constrained to * remove any fixed resources in the domain sub-tree of the given resource type. It then uses * the memory ranges to apply best fit on the resource requirements of the downstream devices. * * Once resources are allocated to all downstream devices of the domain, it walks down each * downstream bridge to continue the same process until resources are allocated to all devices * under the domain. */ static void allocate_domain_resources(const struct device *domain) { struct memranges ranges; struct device *child; const struct resource *res; /* Resource type I/O */ res = find_domain_resource(domain, IORESOURCE_IO); if (res) { setup_resource_ranges(domain, res, IORESOURCE_IO, &ranges); allocate_child_resources(domain->link_list, &ranges, IORESOURCE_TYPE_MASK, IORESOURCE_IO); cleanup_resource_ranges(domain, &ranges, res); } /* * Resource type Mem: * Domain does not distinguish between mem and prefmem resources. Thus, the resource * allocation at domain level considers mem and prefmem together when finding the best * fit based on the biggest resource requirement. * * However, resource requests for allocation above 4G boundary need to be handled * separately if the domain resource window crosses this boundary. There is a single * window for resource of type IORESOURCE_MEM. When creating memranges, this resource * is split into two separate ranges -- one for the window below 4G boundary and other * for the window above 4G boundary (with IORESOURCE_ABOVE_4G flag set). Thus, when * allocating child resources, requests for below and above the 4G boundary are handled * separately by setting the type_mask and type_match to allocate_child_resources() * accordingly. */ res = find_domain_resource(domain, IORESOURCE_MEM); if (res) { setup_resource_ranges(domain, res, IORESOURCE_MEM, &ranges); allocate_child_resources(domain->link_list, &ranges, IORESOURCE_TYPE_MASK | IORESOURCE_ABOVE_4G, IORESOURCE_MEM); allocate_child_resources(domain->link_list, &ranges, IORESOURCE_TYPE_MASK | IORESOURCE_ABOVE_4G, IORESOURCE_MEM | IORESOURCE_ABOVE_4G); cleanup_resource_ranges(domain, &ranges, res); } for (child = domain->link_list->children; child; child = child->sibling) { if (!dev_has_children(child)) continue; /* Continue allocation for all downstream bridges. */ allocate_bridge_resources(child); } } /* * This function forms the guts of the resource allocator. It walks through the entire device * tree for each domain two times. * * Every domain has a fixed set of ranges. These ranges cannot be relaxed based on the * requirements of the downstream devices. They represent the available windows from which * resources can be allocated to the different devices under the domain. * * In order to identify the requirements of downstream devices, resource allocator walks in a * DFS fashion. It gathers the requirements from leaf devices and propagates those back up * to their upstream bridges until the requirements for all the downstream devices of the domain * are gathered. This is referred to as pass 1 of resource allocator. * * Once the requirements for all the devices under the domain are gathered, resource allocator * walks a second time to allocate resources to downstream devices as per the * requirements. It always picks the biggest resource request as per the type (i/o and mem) to * allocate space from its fixed window to the immediate downstream device of the domain. In * order to accomplish best fit for the resources, a list of ranges is maintained by each * resource type (i/o and mem). Domain does not differentiate between mem and prefmem. Since * they are allocated space from the same window, the resource allocator at the domain level * ensures that the biggest requirement is selected indepedent of the prefetch type. Once the * resource allocation for all immediate downstream devices is complete at the domain level, * resource allocator walks down the subtree for each downstream bridge to continue the * allocation process at the bridge level. Since bridges have separate windows for i/o, mem and * prefmem, best fit algorithm at bridge level looks for the biggest requirement considering * prefmem resources separately from non-prefmem resources. This continues until resource * allocation is performed for all downstream bridges in the domain sub-tree. This is referred * to as pass 2 of resource allocator. * * Some rules that are followed by the resource allocator: * - Allocate resource locations for every device as long as the requirements can be satisfied. * - If a resource cannot be allocated any address space, then that resource needs to be * properly updated to ensure that it does not incorrectly overlap some address space reserved * for a different purpose. * - Don't overlap with resources in fixed locations. * - Don't overlap and follow the rules of bridges -- downstream devices of bridges should use * parts of the address space allocated to the bridge. */ void allocate_resources(const struct device *root) { const struct device *child; if ((root == NULL) || (root->link_list == NULL)) return; for (child = root->link_list->children; child; child = child->sibling) { if (child->path.type != DEVICE_PATH_DOMAIN) continue; post_log_path(child); /* Pass 1 - Gather requirements. */ printk(BIOS_INFO, "==== Resource allocator: %s - Pass 1 (gathering requirements) ===\n", dev_path(child)); compute_domain_resources(child); /* Pass 2 - Allocate resources as per gathered requirements. */ printk(BIOS_INFO, "=== Resource allocator: %s - Pass 2 (allocating resources) ===\n", dev_path(child)); allocate_domain_resources(child); printk(BIOS_INFO, "=== Resource allocator: %s - resource allocation complete ===\n", dev_path(child)); } }