[PATCH 7/7] drm/i915: expose energy counter on SNB and IVB

[Ben Widawsky <ben@bwidawsk.net>]

From: Jesse Barnes <jbarnes@virtuousgeek.org>

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@virtuousgeek.org>

v3: by Ben
Tied it into existing rc6  sysfs entries and named that a more generic
"power attrs." Fixed rebase conflicts.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_reg.h   |  2 ++
 drivers/gpu/drm/i915/i915_sysfs.c | 25 +++++++++++++++++++++++--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index d0b60f2..0e34f5f 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1242,6 +1242,8 @@
 #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 e3a31ae..6bbc9af 100644
--- a/drivers/gpu/drm/i915/i915_sysfs.c
+++ b/drivers/gpu/drm/i915/i915_sysfs.c
@@ -76,22 +76,43 @@ show_rc6pp_ms(struct device *kdev, struct device_attribute *attr, char *buf)
 	return snprintf(buf, PAGE_SIZE, "%u", rc6pp_residency);
 }
 
+#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(rc6_enable, S_IRUGO, show_rc6_mask, NULL);
 static DEVICE_ATTR(rc6_residency_ms, S_IRUGO, show_rc6_ms, NULL);
 static DEVICE_ATTR(rc6p_residency_ms, S_IRUGO, show_rc6p_ms, NULL);
 static DEVICE_ATTR(rc6pp_residency_ms, S_IRUGO, show_rc6pp_ms, NULL);
+static DEVICE_ATTR(gt_energy_uJ, S_IRUGO, show_gt_energy_uJ, NULL);
 
-static struct attribute *rc6_attrs[] = {
+static struct attribute *power_attrs[] = {
 	&dev_attr_rc6_enable.attr,
 	&dev_attr_rc6_residency_ms.attr,
 	&dev_attr_rc6p_residency_ms.attr,
 	&dev_attr_rc6pp_residency_ms.attr,
+	&dev_attr_gt_energy_uJ.attr,
 	NULL
 };
 
 static struct attribute_group rc6_attr_group = {
 	.name = power_group_name,
-	.attrs =  rc6_attrs
+	.attrs =  power_attrs
 };
 #endif
 
-- 
1.7.12