diff options
Diffstat (limited to 'drivers/acpi/resource.c')
| -rw-r--r-- | drivers/acpi/resource.c | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c index 8244f013f210..fcb7807ea8b7 100644 --- a/drivers/acpi/resource.c +++ b/drivers/acpi/resource.c @@ -26,6 +26,7 @@ #include <linux/device.h> #include <linux/export.h> #include <linux/ioport.h> +#include <linux/list.h> #include <linux/slab.h> #ifdef CONFIG_X86 @@ -621,3 +622,162 @@ int acpi_dev_filter_resource_type(struct acpi_resource *ares, return (type & types) ? 0 : 1; } EXPORT_SYMBOL_GPL(acpi_dev_filter_resource_type); + +struct reserved_region { + struct list_head node; + u64 start; + u64 end; +}; + +static LIST_HEAD(reserved_io_regions); +static LIST_HEAD(reserved_mem_regions); + +static int request_range(u64 start, u64 end, u8 space_id, unsigned long flags, + char *desc) +{ + unsigned int length = end - start + 1; + struct resource *res; + + res = space_id == ACPI_ADR_SPACE_SYSTEM_IO ? + request_region(start, length, desc) : + request_mem_region(start, length, desc); + if (!res) + return -EIO; + + res->flags &= ~flags; + return 0; +} + +static int add_region_before(u64 start, u64 end, u8 space_id, + unsigned long flags, char *desc, + struct list_head *head) +{ + struct reserved_region *reg; + int error; + + reg = kmalloc(sizeof(*reg), GFP_KERNEL); + if (!reg) + return -ENOMEM; + + error = request_range(start, end, space_id, flags, desc); + if (error) + return error; + + reg->start = start; + reg->end = end; + list_add_tail(®->node, head); + return 0; +} + +/** + * acpi_reserve_region - Reserve an I/O or memory region as a system resource. + * @start: Starting address of the region. + * @length: Length of the region. + * @space_id: Identifier of address space to reserve the region from. + * @flags: Resource flags to clear for the region after requesting it. + * @desc: Region description (for messages). + * + * Reserve an I/O or memory region as a system resource to prevent others from + * using it. If the new region overlaps with one of the regions (in the given + * address space) already reserved by this routine, only the non-overlapping + * parts of it will be reserved. + * + * Returned is either 0 (success) or a negative error code indicating a resource + * reservation problem. It is the code of the first encountered error, but the + * routine doesn't abort until it has attempted to request all of the parts of + * the new region that don't overlap with other regions reserved previously. + * + * The resources requested by this routine are never released. + */ +int acpi_reserve_region(u64 start, unsigned int length, u8 space_id, + unsigned long flags, char *desc) +{ + struct list_head *regions; + struct reserved_region *reg; + u64 end = start + length - 1; + int ret = 0, error = 0; + + if (space_id == ACPI_ADR_SPACE_SYSTEM_IO) + regions = &reserved_io_regions; + else if (space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) + regions = &reserved_mem_regions; + else + return -EINVAL; + + if (list_empty(regions)) + return add_region_before(start, end, space_id, flags, desc, regions); + + list_for_each_entry(reg, regions, node) + if (reg->start == end + 1) { + /* The new region can be prepended to this one. */ + ret = request_range(start, end, space_id, flags, desc); + if (!ret) + reg->start = start; + + return ret; + } else if (reg->start > end) { + /* No overlap. Add the new region here and get out. */ + return add_region_before(start, end, space_id, flags, + desc, ®->node); + } else if (reg->end == start - 1) { + goto combine; + } else if (reg->end >= start) { + goto overlap; + } + + /* The new region goes after the last existing one. */ + return add_region_before(start, end, space_id, flags, desc, regions); + + overlap: + /* + * The new region overlaps an existing one. + * + * The head part of the new region immediately preceding the existing + * overlapping one can be combined with it right away. + */ + if (reg->start > start) { + error = request_range(start, reg->start - 1, space_id, flags, desc); + if (error) + ret = error; + else + reg->start = start; + } + + combine: + /* + * The new region is adjacent to an existing one. If it extends beyond + * that region all the way to the next one, it is possible to combine + * all three of them. + */ + while (reg->end < end) { + struct reserved_region *next = NULL; + u64 a = reg->end + 1, b = end; + + if (!list_is_last(®->node, regions)) { + next = list_next_entry(reg, node); + if (next->start <= end) + b = next->start - 1; + } + error = request_range(a, b, space_id, flags, desc); + if (!error) { + if (next && next->start == b + 1) { + reg->end = next->end; + list_del(&next->node); + kfree(next); + } else { + reg->end = end; + break; + } + } else if (next) { + if (!ret) + ret = error; + + reg = next; + } else { + break; + } + } + + return ret ? ret : error; +} +EXPORT_SYMBOL_GPL(acpi_reserve_region); |