[PATCH RESEND v2 2/3] arm64: split counter validation function

[Ionela Voinescu]

In order for the counter validation function to be reused, split
validate_cpu_freq_invariance_counters() into:
 - freq_counters_valid(cpu) - check cpu for valid cycle counters
 - freq_inv_set_max_ratio(int cpu, u64 max_rate, u64 ref_rate) -
   generic function that sets the normalization ratio used by
   topology_scale_freq_tick()

Signed-off-by: Ionela Voinescu <ionela.voine...@arm.com>
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <w...@kernel.org>
---
 arch/arm64/kernel/topology.c | 44 +++++++++++++++++++++---------------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index db03c440e157..764fdb0f947b 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -152,45 +152,49 @@ void update_freq_counters_refs(void)
        this_cpu_write(arch_const_cycles_prev, read_constcnt());
 }
 
-static int validate_cpu_freq_invariance_counters(int cpu)
+static inline bool freq_counters_valid(int cpu)
 {
-       u64 max_freq_hz, ratio;
-
        if (!cpu_has_amu_feat(cpu)) {
                pr_debug("CPU%d: counters are not supported.\n", cpu);
-               return -EINVAL;
+               return false;
        }
 
        if (unlikely(!per_cpu(arch_const_cycles_prev, cpu) ||
                     !per_cpu(arch_core_cycles_prev, cpu))) {
                pr_debug("CPU%d: cycle counters are not enabled.\n", cpu);
-               return -EINVAL;
+               return false;
        }
 
-       /* Convert maximum frequency from KHz to Hz and validate */
-       max_freq_hz = cpufreq_get_hw_max_freq(cpu) * 1000;
-       if (unlikely(!max_freq_hz)) {
-               pr_debug("CPU%d: invalid maximum frequency.\n", cpu);
+       return true;
+}
+
+static int freq_inv_set_max_ratio(int cpu, u64 max_rate, u64 ref_rate)
+{
+       u64 ratio;
+
+       if (unlikely(!max_rate || !ref_rate)) {
+               pr_debug("CPU%d: invalid maximum or reference frequency.\n",
+                        cpu);
                return -EINVAL;
        }
 
        /*
         * Pre-compute the fixed ratio between the frequency of the constant
-        * counter and the maximum frequency of the CPU.
+        * reference counter and the maximum frequency of the CPU.
         *
-        *                            const_freq
-        * arch_max_freq_scale =   ---------------- * SCHED_CAPACITY_SCALE²
-        *                         cpuinfo_max_freq
+        *                          ref_rate
+        * arch_max_freq_scale =   ---------- * SCHED_CAPACITY_SCALE²
+        *                          max_rate
         *
         * We use a factor of 2 * SCHED_CAPACITY_SHIFT -> SCHED_CAPACITY_SCALE²
         * in order to ensure a good resolution for arch_max_freq_scale for
-        * very low arch timer frequencies (down to the KHz range which should
+        * very low reference frequencies (down to the KHz range which should
         * be unlikely).
         */
-       ratio = (u64)arch_timer_get_rate() << (2 * SCHED_CAPACITY_SHIFT);
-       ratio = div64_u64(ratio, max_freq_hz);
+       ratio = ref_rate << (2 * SCHED_CAPACITY_SHIFT);
+       ratio = div64_u64(ratio, max_rate);
        if (!ratio) {
-               WARN_ONCE(1, "System timer frequency too low.\n");
+               WARN_ONCE(1, "Reference frequency too low.\n");
                return -EINVAL;
        }
 
@@ -237,8 +241,12 @@ static int __init init_amu_fie(void)
        }
 
        for_each_present_cpu(cpu) {
-               if (validate_cpu_freq_invariance_counters(cpu))
+               if (!freq_counters_valid(cpu) ||
+                   freq_inv_set_max_ratio(cpu,
+                                          cpufreq_get_hw_max_freq(cpu) * 1000,
+                                          arch_timer_get_rate()))
                        continue;
+
                cpumask_set_cpu(cpu, valid_cpus);
                have_policy |= enable_policy_freq_counters(cpu, valid_cpus);
        }
-- 
2.17.1