| /* SPDX-License-Identifier: GPL-2.0-only */ |
| |
| #include <console/console.h> |
| #include <device/device.h> |
| #include <memrange.h> |
| #include <post.h> |
| |
| /** |
| * 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 resources |
| * 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 in space above |
| * the 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, at the bridge level, the resource allocator 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, the 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 the 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 a memrange for entire address space. |
| * So, this function punches holes in the address space for all fixed |
| * resources that are already defined. Both I/O 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 the 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 the resource allocator. |
| * |
| * Once the requirements for all the devices under the domain are |
| * gathered, the 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). At the domain level we don't 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 independent of the prefetch type. Once the |
| * resource allocation for all immediate downstream devices is complete |
| * at the domain level, the 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 the 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. |
| * - 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)); |
| } |
| } |