intel_idle: add BXT support

Broxton has all the HSW C-states, except C3.
BXT C-state timing is slightly different.

Here we trust the IRTL MSRs as authority
on maximum C-state latency, and override the driver's tables
with the values found in the associated IRTL MSRs.
Further we set the target_residency to 1x maximum latency,
trusting the hardware demotion logic.

Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 145 insertions, 0 deletions

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index b05402ef3b84..73d66fa48638 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -162,6 +162,14 @@
 #define MSR_PKG_C9_RESIDENCY            0x00000631
 #define MSR_PKG_C10_RESIDENCY           0x00000632
 
+/* Interrupt Response Limit */
+#define MSR_PKGC3_IRTL                  0x0000060a
+#define MSR_PKGC6_IRTL                  0x0000060b
+#define MSR_PKGC7_IRTL                  0x0000060c
+#define MSR_PKGC8_IRTL                  0x00000633
+#define MSR_PKGC9_IRTL                  0x00000634
+#define MSR_PKGC10_IRTL                 0x00000635
+
 /* Run Time Average Power Limiting (RAPL) Interface */
 
 #define MSR_RAPL_POWER_UNIT             0x00000606
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index c6935de425fa..c96649292b55 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -766,6 +766,67 @@ static struct cpuidle_state knl_cstates[] = {
                 .enter = NULL }
 };
 
+static struct cpuidle_state bxt_cstates[] = {
+        {
+                .name = "C1-BXT",
+                .desc = "MWAIT 0x00",
+                .flags = MWAIT2flg(0x00),
+                .exit_latency = 2,
+                .target_residency = 2,
+                .enter = &intel_idle,
+                .enter_freeze = intel_idle_freeze, },
+        {
+                .name = "C1E-BXT",
+                .desc = "MWAIT 0x01",
+                .flags = MWAIT2flg(0x01),
+                .exit_latency = 10,
+                .target_residency = 20,
+                .enter = &intel_idle,
+                .enter_freeze = intel_idle_freeze, },
+        {
+                .name = "C6-BXT",
+                .desc = "MWAIT 0x20",
+                .flags = MWAIT2flg(0x20) | CPUIDLE_FLAG_TLB_FLUSHED,
+                .exit_latency = 133,
+                .target_residency = 133,
+                .enter = &intel_idle,
+                .enter_freeze = intel_idle_freeze, },
+        {
+                .name = "C7s-BXT",
+                .desc = "MWAIT 0x31",
+                .flags = MWAIT2flg(0x31) | CPUIDLE_FLAG_TLB_FLUSHED,
+                .exit_latency = 155,
+                .target_residency = 155,
+                .enter = &intel_idle,
+                .enter_freeze = intel_idle_freeze, },
+        {
+                .name = "C8-BXT",
+                .desc = "MWAIT 0x40",
+                .flags = MWAIT2flg(0x40) | CPUIDLE_FLAG_TLB_FLUSHED,
+                .exit_latency = 1000,
+                .target_residency = 1000,
+                .enter = &intel_idle,
+                .enter_freeze = intel_idle_freeze, },
+        {
+                .name = "C9-BXT",
+                .desc = "MWAIT 0x50",
+                .flags = MWAIT2flg(0x50) | CPUIDLE_FLAG_TLB_FLUSHED,
+                .exit_latency = 2000,
+                .target_residency = 2000,
+                .enter = &intel_idle,
+                .enter_freeze = intel_idle_freeze, },
+        {
+                .name = "C10-BXT",
+                .desc = "MWAIT 0x60",
+                .flags = MWAIT2flg(0x60) | CPUIDLE_FLAG_TLB_FLUSHED,
+                .exit_latency = 10000,
+                .target_residency = 10000,
+                .enter = &intel_idle,
+                .enter_freeze = intel_idle_freeze, },
+        {
+                .enter = NULL }
+};
+
 /**
  * intel_idle
  * @dev: cpuidle_device
@@ -950,6 +1011,11 @@ static const struct idle_cpu idle_cpu_knl = {
         .state_table = knl_cstates,
 };
 
+static const struct idle_cpu idle_cpu_bxt = {
+        .state_table = bxt_cstates,
+        .disable_promotion_to_c1e = true,
+};
+
 #define ICPU(model, cpu) \
         { X86_VENDOR_INTEL, 6, model, X86_FEATURE_MWAIT, (unsigned long)&cpu }
 
@@ -985,6 +1051,7 @@ static const struct x86_cpu_id intel_idle_ids[] __initconst = {
         ICPU(0x9e, idle_cpu_skl),
         ICPU(0x55, idle_cpu_skx),
         ICPU(0x57, idle_cpu_knl),
+        ICPU(0x5c, idle_cpu_bxt),
         {}
 };
 MODULE_DEVICE_TABLE(x86cpu, intel_idle_ids);
@@ -1075,6 +1142,73 @@ static void ivt_idle_state_table_update(void)
 
         /* else, 1 and 2 socket systems use default ivt_cstates */
 }
+
+/*
+ * Translate IRTL (Interrupt Response Time Limit) MSR to usec
+ */
+
+static unsigned int irtl_ns_units[] = {
+        1, 32, 1024, 32768, 1048576, 33554432, 0, 0 };
+
+static unsigned long long irtl_2_usec(unsigned long long irtl)
+{
+        unsigned long long ns;
+
+        ns = irtl_ns_units[(irtl >> 10) & 0x3];
+
+        return div64_u64((irtl & 0x3FF) * ns, 1000);
+}
+/*
+ * bxt_idle_state_table_update(void)
+ *
+ * On BXT, we trust the IRTL to show the definitive maximum latency
+ * We use the same value for target_residency.
+ */
+static void bxt_idle_state_table_update(void)
+{
+        unsigned long long msr;
+
+        rdmsrl(MSR_PKGC6_IRTL, msr);
+        if (msr) {
+                unsigned int usec = irtl_2_usec(msr);
+
+                bxt_cstates[2].exit_latency = usec;
+                bxt_cstates[2].target_residency = usec;
+        }
+
+        rdmsrl(MSR_PKGC7_IRTL, msr);
+        if (msr) {
+                unsigned int usec = irtl_2_usec(msr);
+
+                bxt_cstates[3].exit_latency = usec;
+                bxt_cstates[3].target_residency = usec;
+        }
+
+        rdmsrl(MSR_PKGC8_IRTL, msr);
+        if (msr) {
+                unsigned int usec = irtl_2_usec(msr);
+
+                bxt_cstates[4].exit_latency = usec;
+                bxt_cstates[4].target_residency = usec;
+        }
+
+        rdmsrl(MSR_PKGC9_IRTL, msr);
+        if (msr) {
+                unsigned int usec = irtl_2_usec(msr);
+
+                bxt_cstates[5].exit_latency = usec;
+                bxt_cstates[5].target_residency = usec;
+        }
+
+        rdmsrl(MSR_PKGC10_IRTL, msr);
+        if (msr) {
+                unsigned int usec = irtl_2_usec(msr);
+
+                bxt_cstates[6].exit_latency = usec;
+                bxt_cstates[6].target_residency = usec;
+        }
+
+}
 /*
  * sklh_idle_state_table_update(void)
  *
@@ -1130,6 +1264,9 @@ static void intel_idle_state_table_update(void)
         case 0x3e: /* IVT */
                 ivt_idle_state_table_update();
                 break;
+        case 0x5c: /* BXT */
+                bxt_idle_state_table_update();
+                break;
         case 0x5e: /* SKL-H */
                 sklh_idle_state_table_update();
                 break;