drm/i915: Extract PCU communication

There is a special mechanism for communicating with the PCU already
being used for the ring frequency stuff. As we'll be needing this for
other commands, extract it now to make future code less error prone and
the current code more reusable.

I'm not entirely sure if this code matches 1:1 with the previous code
behaviorally. Functionally however, it should be the same.

CC: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
[danvet: Fixup compile fail reported by Wu Fengguang.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -1283,15 +1283,10 @@ static int i915_ring_freq_table(struct seq_file *m, void *unused)
 	for (gpu_freq = dev_priv->rps.min_delay;
 	     gpu_freq <= dev_priv->rps.max_delay;
 	     gpu_freq++) {
-		I915_WRITE(GEN6_PCODE_DATA, gpu_freq);
-		I915_WRITE(GEN6_PCODE_MAILBOX, GEN6_PCODE_READY |
-			   GEN6_PCODE_READ_MIN_FREQ_TABLE);
-		if (wait_for((I915_READ(GEN6_PCODE_MAILBOX) &
-			      GEN6_PCODE_READY) == 0, 10)) {
-			DRM_ERROR("pcode read of freq table timed out\n");
-			continue;
-		}
-		ia_freq = I915_READ(GEN6_PCODE_DATA);
+		ia_freq = gpu_freq;
+		sandybridge_pcode_read(dev_priv,
+				       GEN6_PCODE_READ_MIN_FREQ_TABLE,
+				       &ia_freq);
 		seq_printf(m, "%d\t\t%d\n", gpu_freq * GT_FREQUENCY_MULTIPLIER, ia_freq * 100);
 	}
 

drivers/gpu/drm/i915/i915_drv.h

@@ -1630,6 +1630,9 @@ void gen6_gt_force_wake_get(struct drm_i915_private *dev_priv);
 void gen6_gt_force_wake_put(struct drm_i915_private *dev_priv);
 int __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv);
 
+int sandybridge_pcode_read(struct drm_i915_private *dev_priv, u8 mbox, u32 *val);
+int sandybridge_pcode_write(struct drm_i915_private *dev_priv, u8 mbox, u32 val);
+
 #define __i915_read(x, y) \
 	u##x i915_read##x(struct drm_i915_private *dev_priv, u32 reg);
 

drivers/gpu/drm/i915/intel_pm.c

@@ -2407,7 +2407,7 @@ static void gen6_enable_rps(struct drm_device *dev)
 	u32 pcu_mbox, rc6_mask = 0;
 	u32 gtfifodbg;
 	int rc6_mode;
-	int i;
+	int i, ret;
 
 	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 
@@ -2503,30 +2503,16 @@ static void gen6_enable_rps(struct drm_device *dev)
 		   GEN6_RP_UP_BUSY_AVG |
 		   (IS_HASWELL(dev) ? GEN7_RP_DOWN_IDLE_AVG : GEN6_RP_DOWN_IDLE_CONT));
 
-	if (wait_for((I915_READ(GEN6_PCODE_MAILBOX) & GEN6_PCODE_READY) == 0,
-		     500))
-		DRM_ERROR("timeout waiting for pcode mailbox to become idle\n");
-
-	I915_WRITE(GEN6_PCODE_DATA, 0);
-	I915_WRITE(GEN6_PCODE_MAILBOX,
-		   GEN6_PCODE_READY |
-		   GEN6_PCODE_WRITE_MIN_FREQ_TABLE);
-	if (wait_for((I915_READ(GEN6_PCODE_MAILBOX) & GEN6_PCODE_READY) == 0,
-		     500))
-		DRM_ERROR("timeout waiting for pcode mailbox to finish\n");
-
-	/* Check for overclock support */
-	if (wait_for((I915_READ(GEN6_PCODE_MAILBOX) & GEN6_PCODE_READY) == 0,
-		     500))
-		DRM_ERROR("timeout waiting for pcode mailbox to become idle\n");
-	I915_WRITE(GEN6_PCODE_MAILBOX, GEN6_READ_OC_PARAMS);
-	pcu_mbox = I915_READ(GEN6_PCODE_DATA);
-	if (wait_for((I915_READ(GEN6_PCODE_MAILBOX) & GEN6_PCODE_READY) == 0,
-		     500))
-		DRM_ERROR("timeout waiting for pcode mailbox to finish\n");
-	if (pcu_mbox & (1<<31)) { /* OC supported */
-		dev_priv->rps.max_delay = pcu_mbox & 0xff;
-		DRM_DEBUG_DRIVER("overclocking supported, adjusting frequency max to %dMHz\n", pcu_mbox * 50);
+	ret = sandybridge_pcode_write(dev_priv, GEN6_PCODE_WRITE_MIN_FREQ_TABLE, 0);
+	if (!ret) {
+		pcu_mbox = 0;
+		ret = sandybridge_pcode_read(dev_priv, GEN6_READ_OC_PARAMS, &pcu_mbox);
+		if (ret && pcu_mbox & (1<<31)) { /* OC supported */
+			dev_priv->rps.max_delay = pcu_mbox & 0xff;
+			DRM_DEBUG_DRIVER("overclocking supported, adjusting frequency max to %dMHz\n", pcu_mbox * 50);
+		}
+	} else {
+		DRM_DEBUG_DRIVER("Failed to set the min frequency\n");
 	}
 
 	gen6_set_rps(dev_priv->dev, (gt_perf_status & 0xff00) >> 8);
@@ -2581,17 +2567,11 @@ static void gen6_update_ring_freq(struct drm_device *dev)
 		else
 			ia_freq = max_ia_freq - ((diff * scaling_factor) / 2);
 		ia_freq = DIV_ROUND_CLOSEST(ia_freq, 100);
+		ia_freq <<= GEN6_PCODE_FREQ_IA_RATIO_SHIFT;
 
-		I915_WRITE(GEN6_PCODE_DATA,
-			   (ia_freq << GEN6_PCODE_FREQ_IA_RATIO_SHIFT) |
-			   gpu_freq);
-		I915_WRITE(GEN6_PCODE_MAILBOX, GEN6_PCODE_READY |
-			   GEN6_PCODE_WRITE_MIN_FREQ_TABLE);
-		if (wait_for((I915_READ(GEN6_PCODE_MAILBOX) &
-			      GEN6_PCODE_READY) == 0, 10)) {
-			DRM_ERROR("pcode write of freq table timed out\n");
-			continue;
-		}
+		sandybridge_pcode_write(dev_priv,
+					GEN6_PCODE_WRITE_MIN_FREQ_TABLE,
+					ia_freq | gpu_freq);
 	}
 }
 
@@ -4152,3 +4132,49 @@ void intel_gt_init(struct drm_device *dev)
 	}
 }
 
+int sandybridge_pcode_read(struct drm_i915_private *dev_priv, u8 mbox, u32 *val)
+{
+	WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
+
+	if (I915_READ(GEN6_PCODE_MAILBOX) & GEN6_PCODE_READY) {
+		DRM_DEBUG_DRIVER("warning: pcode (read) mailbox access failed\n");
+		return -EAGAIN;
+	}
+
+	I915_WRITE(GEN6_PCODE_DATA, *val);
+	I915_WRITE(GEN6_PCODE_MAILBOX, GEN6_PCODE_READY | mbox);
+
+	if (wait_for((I915_READ(GEN6_PCODE_MAILBOX) & GEN6_PCODE_READY) == 0,
+		     500)) {
+		DRM_ERROR("timeout waiting for pcode read (%d) to finish\n", mbox);
+		return -ETIMEDOUT;
+	}
+
+	*val = I915_READ(GEN6_PCODE_DATA);
+	I915_WRITE(GEN6_PCODE_DATA, 0);
+
+	return 0;
+}
+
+int sandybridge_pcode_write(struct drm_i915_private *dev_priv, u8 mbox, u32 val)
+{
+	WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
+
+	if (I915_READ(GEN6_PCODE_MAILBOX) & GEN6_PCODE_READY) {
+		DRM_DEBUG_DRIVER("warning: pcode (write) mailbox access failed\n");
+		return -EAGAIN;
+	}
+
+	I915_WRITE(GEN6_PCODE_DATA, val);
+	I915_WRITE(GEN6_PCODE_MAILBOX, GEN6_PCODE_READY | mbox);
+
+	if (wait_for((I915_READ(GEN6_PCODE_MAILBOX) & GEN6_PCODE_READY) == 0,
+		     500)) {
+		DRM_ERROR("timeout waiting for pcode write (%d) to finish\n", mbox);
+		return -ETIMEDOUT;
+	}
+
+	I915_WRITE(GEN6_PCODE_DATA, 0);
+
+	return 0;
+}