diff options
Diffstat (limited to 'arch/arm/kernel/devtree.c')
| -rw-r--r-- | arch/arm/kernel/devtree.c | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c index bee7f9d47f0..aaf9add497f 100644 --- a/arch/arm/kernel/devtree.c +++ b/arch/arm/kernel/devtree.c @@ -19,8 +19,10 @@ #include <linux/of_irq.h> #include <linux/of_platform.h> +#include <asm/cputype.h> #include <asm/setup.h> #include <asm/page.h> +#include <asm/smp_plat.h> #include <asm/mach/arch.h> #include <asm/mach-types.h> @@ -61,6 +63,104 @@ void __init arm_dt_memblock_reserve(void) } } +/* + * arm_dt_init_cpu_maps - Function retrieves cpu nodes from the device tree + * and builds the cpu logical map array containing MPIDR values related to + * logical cpus + * + * Updates the cpu possible mask with the number of parsed cpu nodes + */ +void __init arm_dt_init_cpu_maps(void) +{ + /* + * Temp logical map is initialized with UINT_MAX values that are + * considered invalid logical map entries since the logical map must + * contain a list of MPIDR[23:0] values where MPIDR[31:24] must + * read as 0. + */ + struct device_node *cpu, *cpus; + u32 i, j, cpuidx = 1; + u32 mpidr = is_smp() ? read_cpuid_mpidr() & MPIDR_HWID_BITMASK : 0; + + u32 tmp_map[NR_CPUS] = { [0 ... NR_CPUS-1] = UINT_MAX }; + bool bootcpu_valid = false; + cpus = of_find_node_by_path("/cpus"); + + if (!cpus) + return; + + for_each_child_of_node(cpus, cpu) { + u32 hwid; + + pr_debug(" * %s...\n", cpu->full_name); + /* + * A device tree containing CPU nodes with missing "reg" + * properties is considered invalid to build the + * cpu_logical_map. + */ + if (of_property_read_u32(cpu, "reg", &hwid)) { + pr_debug(" * %s missing reg property\n", + cpu->full_name); + return; + } + + /* + * 8 MSBs must be set to 0 in the DT since the reg property + * defines the MPIDR[23:0]. + */ + if (hwid & ~MPIDR_HWID_BITMASK) + return; + + /* + * Duplicate MPIDRs are a recipe for disaster. + * Scan all initialized entries and check for + * duplicates. If any is found just bail out. + * temp values were initialized to UINT_MAX + * to avoid matching valid MPIDR[23:0] values. + */ + for (j = 0; j < cpuidx; j++) + if (WARN(tmp_map[j] == hwid, "Duplicate /cpu reg " + "properties in the DT\n")) + return; + + /* + * Build a stashed array of MPIDR values. Numbering scheme + * requires that if detected the boot CPU must be assigned + * logical id 0. Other CPUs get sequential indexes starting + * from 1. If a CPU node with a reg property matching the + * boot CPU MPIDR is detected, this is recorded so that the + * logical map built from DT is validated and can be used + * to override the map created in smp_setup_processor_id(). + */ + if (hwid == mpidr) { + i = 0; + bootcpu_valid = true; + } else { + i = cpuidx++; + } + + tmp_map[i] = hwid; + + if (cpuidx > nr_cpu_ids) + break; + } + + if (WARN(!bootcpu_valid, "DT missing boot CPU MPIDR[23:0], " + "fall back to default cpu_logical_map\n")) + return; + + /* + * Since the boot CPU node contains proper data, and all nodes have + * a reg property, the DT CPU list can be considered valid and the + * logical map created in smp_setup_processor_id() can be overridden + */ + for (i = 0; i < cpuidx; i++) { + set_cpu_possible(i, true); + cpu_logical_map(i) = tmp_map[i]; + pr_debug("cpu logical map 0x%x\n", cpu_logical_map(i)); + } +} + /** * setup_machine_fdt - Machine setup when an dtb was passed to the kernel * @dt_phys: physical address of dt blob |