From: Zi Shen Lim zlim@broadcom.com
Create cpu topology based on MPIDR. When hardware sets MPIDR to sane values, this method will always work. Therefore it should also work well as the fallback method. [1]
When we have multiple processing elements in the system, we create the cpu topology by mapping each affinity level (from lowest to highest) to threads (if they exist), cores, and clusters.
We combine data from all higher affinity levels into cluster_id so we don't lose any information from MPIDR. [2]
[1] http://www.spinics.net/lists/arm-kernel/msg317445.html [2] https://lkml.org/lkml/2014/4/23/703
Signed-off-by: Zi Shen Lim zlim@broadcom.com Signed-off-by: Mark Brown broonie@linaro.org --- arch/arm64/include/asm/cputype.h | 2 ++ arch/arm64/kernel/topology.c | 51 +++++++++++++++++++++++++++++----------- 2 files changed, 39 insertions(+), 14 deletions(-)
diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h index 27f54a7cc81b..ed48a3a7836a 100644 --- a/arch/arm64/include/asm/cputype.h +++ b/arch/arm64/include/asm/cputype.h @@ -18,6 +18,8 @@
#define INVALID_HWID ULONG_MAX
+#define MPIDR_UP_BITMASK (0x1 << 30) +#define MPIDR_MT_BITMASK (0x1 << 24) #define MPIDR_HWID_BITMASK 0xff00ffffff
#define MPIDR_LEVEL_BITS_SHIFT 3 diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 43514f905916..9a0160068503 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -20,6 +20,7 @@ #include <linux/of.h> #include <linux/sched.h>
+#include <asm/cputype.h> #include <asm/topology.h>
static int __init get_cpu_for_node(struct device_node *node) @@ -188,13 +189,9 @@ static int __init parse_dt_topology(void) * Check that all cores are in the topology; the SMP code will * only mark cores described in the DT as possible. */ - for_each_possible_cpu(cpu) { - if (cpu_topology[cpu].cluster_id == -1) { - pr_err("CPU%d: No topology information specified\n", - cpu); + for_each_possible_cpu(cpu) + if (cpu_topology[cpu].cluster_id == -1) ret = -EINVAL; - } - }
out_map: of_node_put(map); @@ -219,14 +216,6 @@ static void update_siblings_masks(unsigned int cpuid) struct cpu_topology *cpu_topo, *cpuid_topo = &cpu_topology[cpuid]; int cpu;
- if (cpuid_topo->cluster_id == -1) { - /* - * DT does not contain topology information for this cpu. - */ - pr_debug("CPU%u: No topology information configured\n", cpuid); - return; - } - /* update core and thread sibling masks */ for_each_possible_cpu(cpu) { cpu_topo = &cpu_topology[cpu]; @@ -249,6 +238,40 @@ static void update_siblings_masks(unsigned int cpuid)
void store_cpu_topology(unsigned int cpuid) { + struct cpu_topology *cpuid_topo = &cpu_topology[cpuid]; + u64 mpidr; + + if (cpuid_topo->cluster_id != -1) + goto topology_populated; + + mpidr = read_cpuid_mpidr(); + + /* Create cpu topology mapping based on MPIDR. */ + if (mpidr & MPIDR_UP_BITMASK) { + /* Uniprocessor system */ + cpuid_topo->thread_id = -1; + cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0); + cpuid_topo->cluster_id = 0; + } else if (mpidr & MPIDR_MT_BITMASK) { + /* Multiprocessor system : Multi-threads per core */ + cpuid_topo->thread_id = MPIDR_AFFINITY_LEVEL(mpidr, 0); + cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 1); + cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL(mpidr, 2) | + MPIDR_AFFINITY_LEVEL(mpidr, 3) << 8; + } else { + /* Multiprocessor system : Single-thread per core */ + cpuid_topo->thread_id = -1; + cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0); + cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL(mpidr, 1) | + MPIDR_AFFINITY_LEVEL(mpidr, 2) << 8 | + MPIDR_AFFINITY_LEVEL(mpidr, 3) << 16; + } + + pr_debug("CPU%u: cluster %d core %d thread %d mpidr %llx\n", + cpuid, cpuid_topo->cluster_id, cpuid_topo->core_id, + cpuid_topo->thread_id, mpidr); + +topology_populated: update_siblings_masks(cpuid); }