[PATCH] drm/i915: expose energy counter on SNB and IVB

[jbarnes at virtuousgeek.org (Jesse Barnes)]

On SNB and IVB, there's an MSR (also exposed through MCHBAR) we can use
to read out the amount of energy used over time.  Expose this in sysfs
to make it easy to do power comparisons with different configurations.

If the platform supports it, the file will show up under the
drm/card0/power subdirectory of the PCI device in sysfs as gt_energy_uJ.
The value in the file is a running total of energy (in microjoules)
consumed by the graphics device.

v2: move to sysfs (Ben, Daniel)
    expose a simple value (Chris)
    drop unrelated hunk (Ben)

Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
---
 drivers/gpu/drm/i915/i915_reg.h   |    2 +
 drivers/gpu/drm/i915/i915_sysfs.c |   39 +++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 0a61481..ca6a620 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1224,6 +1224,8 @@
 #define CLKCFG_MEM_800					(3 << 4)
 #define CLKCFG_MEM_MASK					(7 << 4)
 
+#define SECP_NRG_STTS			(MCHBAR_MIRROR_BASE_SNB + 0x592c)
+
 #define TSC1			0x11001
 #define   TSE			(1<<0)
 #define TR1			0x11006
diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
index 2f5388a..c7fe7bd 100644
--- a/drivers/gpu/drm/i915/i915_sysfs.c
+++ b/drivers/gpu/drm/i915/i915_sysfs.c
@@ -93,6 +93,37 @@ static struct attribute_group rc6_attr_group = {
 	.attrs =  rc6_attrs
 };
 
+#define MSR_IA32_PACKAGE_POWER_SKU_UNIT		0x00000606
+
+static ssize_t
+show_gt_energy_uJ(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct drm_minor *dminor = container_of(dev, struct drm_minor, kdev);
+	struct drm_i915_private *dev_priv = dminor->dev->dev_private;
+	u64 ppsu;
+	u32 val, units;
+
+	rdmsrl(MSR_IA32_PACKAGE_POWER_SKU_UNIT, ppsu);
+
+	ppsu = (ppsu & 0x1f00) >> 8;
+	units = 1000000 / (1 << ppsu); /* convert to uJ */
+	val = I915_READ(SECP_NRG_STTS);
+
+	return snprintf(buf, PAGE_SIZE, "%u", val * units);
+}
+
+static DEVICE_ATTR(gt_energy_uJ, S_IRUGO, show_gt_energy_uJ, NULL);
+
+static struct attribute *gt_attrs[] = {
+	&dev_attr_gt_energy_uJ.attr,
+	NULL,
+};
+
+static struct attribute_group gt_attr_group = {
+	.name = power_group_name,
+	.attrs = gt_attrs,
+};
+
 static int l3_access_valid(struct drm_device *dev, loff_t offset)
 {
 	if (!IS_IVYBRIDGE(dev))
@@ -217,10 +248,18 @@ void i915_setup_sysfs(struct drm_device *dev)
 		if (ret)
 			DRM_ERROR("l3 parity sysfs setup failed\n");
 	}
+
+	if (IS_GEN6(dev) || IS_IVYBRIDGE(dev)) {
+		ret = sysfs_merge_group(&dev->primary->kdev.kobj,
+					&gt_attr_group);
+		if (ret)
+			DRM_ERROR("GT energy sysfs setup failed\n");
+	}
 }
 
 void i915_teardown_sysfs(struct drm_device *dev)
 {
 	device_remove_bin_file(&dev->primary->kdev,  &dpf_attrs);
 	sysfs_unmerge_group(&dev->primary->kdev.kobj, &rc6_attr_group);
+	sysfs_unmerge_group(&dev->primary->kdev.kobj, &gt_attr_group);
 }
-- 
1.7.4.1