intel_pstate: Knights Landing support

 1. Add Knights Landing (KNL) CPUID to the list of CPUIDs supported by
    the intel_pstate driver.

 2. Add a new cpu_default structure for KNL since KNL has a slightly
    different mechanism to get turbo pstates from MSRs.

Signed-off-by: Dasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
[ rjw: Subject and changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 8006d86..c5b81be 100644 (file)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -614,6 +614,19 @@ static void core_set_pstate(struct cpudata *cpudata, int pstate)
        wrmsrl_on_cpu(cpudata->cpu, MSR_IA32_PERF_CTL, val);
 }
 
+static int knl_get_turbo_pstate(void)
+{
+       u64 value;
+       int nont, ret;
+
+       rdmsrl(MSR_NHM_TURBO_RATIO_LIMIT, value);
+       nont = core_get_max_pstate();
+       ret = (((value) >> 8) & 0xFF);
+       if (ret <= nont)
+               ret = nont;
+       return ret;
+}
+
 static struct cpu_defaults core_params = {
        .pid_policy = {
                .sample_rate_ms = 10,
@@ -651,6 +664,23 @@ static struct cpu_defaults byt_params = {
        },
 };
 
+static struct cpu_defaults knl_params = {
+       .pid_policy = {
+               .sample_rate_ms = 10,
+               .deadband = 0,
+               .setpoint = 97,
+               .p_gain_pct = 20,
+               .d_gain_pct = 0,
+               .i_gain_pct = 0,
+       },
+       .funcs = {
+               .get_max = core_get_max_pstate,
+               .get_min = core_get_min_pstate,
+               .get_turbo = knl_get_turbo_pstate,
+               .set = core_set_pstate,
+       },
+};
+
 static void intel_pstate_get_min_max(struct cpudata *cpu, int *min, int *max)
 {
        int max_perf = cpu->pstate.turbo_pstate;
@@ -865,6 +895,7 @@ static const struct x86_cpu_id intel_pstate_cpu_ids[] = {
        ICPU(0x4e, core_params),
        ICPU(0x4f, core_params),
        ICPU(0x56, core_params),
+       ICPU(0x57, knl_params),
        {}
 };
 MODULE_DEVICE_TABLE(x86cpu, intel_pstate_cpu_ids);