drm/i915: add a dedicated mutex for VLV/CHV IOSF sideband

The VLV/CHV IOSF sideband is unrelated to pcode. It's just confusing to
piggyback on the same mutex. Add a dedicated lock with init and cleanup
functions.

Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/31ccbf33c6b6114d0bcb40a2e174f19162d4e177.1730193891.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_driver.c

@@ -105,6 +105,7 @@
 #include "intel_pcode.h"
 #include "intel_region_ttm.h"
 #include "intel_sbi.h"
+#include "vlv_sideband.h"
 #include "vlv_suspend.h"
 
 static const struct drm_driver i915_drm_driver;
@@ -233,6 +234,7 @@ static int i915_driver_early_probe(struct drm_i915_private *dev_priv)
 	spin_lock_init(&dev_priv->gpu_error.lock);
 
 	intel_sbi_init(dev_priv);
+	vlv_iosf_sb_init(dev_priv);
 	mutex_init(&dev_priv->sb_lock);
 	cpu_latency_qos_add_request(&dev_priv->sb_qos, PM_QOS_DEFAULT_VALUE);
 
@@ -294,6 +296,7 @@ static void i915_driver_late_release(struct drm_i915_private *dev_priv)
 
 	cpu_latency_qos_remove_request(&dev_priv->sb_qos);
 	mutex_destroy(&dev_priv->sb_lock);
+	vlv_iosf_sb_fini(dev_priv);
 	intel_sbi_fini(dev_priv);
 
 	i915_params_free(&dev_priv->params);

drivers/gpu/drm/i915/i915_drv.h

@@ -239,6 +239,11 @@ struct drm_i915_private {
 	/* LPT/WPT IOSF sideband protection */
 	struct mutex sbi_lock;
 
+	/* VLV/CHV IOSF sideband */
+	struct {
+		struct mutex lock; /* protect sideband access */
+	} vlv_iosf_sb;
+
 	/* Sideband mailbox protection */
 	struct mutex sb_lock;
 	struct pm_qos_request sb_qos;

drivers/gpu/drm/i915/vlv_sideband.c

@@ -62,12 +62,12 @@ void vlv_iosf_sb_get(struct drm_i915_private *i915, unsigned long ports)
 	if (ports & BIT(VLV_IOSF_SB_PUNIT))
 		__vlv_punit_get(i915);
 
-	mutex_lock(&i915->sb_lock);
+	mutex_lock(&i915->vlv_iosf_sb.lock);
 }
 
 void vlv_iosf_sb_put(struct drm_i915_private *i915, unsigned long ports)
 {
-	mutex_unlock(&i915->sb_lock);
+	mutex_unlock(&i915->vlv_iosf_sb.lock);
 
 	if (ports & BIT(VLV_IOSF_SB_PUNIT))
 		__vlv_punit_put(i915);
@@ -81,7 +81,7 @@ static int vlv_sideband_rw(struct drm_i915_private *i915,
 	const bool is_read = (opcode == SB_MRD_NP || opcode == SB_CRRDDA_NP);
 	int err;
 
-	lockdep_assert_held(&i915->sb_lock);
+	lockdep_assert_held(&i915->vlv_iosf_sb.lock);
 	if (port == IOSF_PORT_PUNIT)
 		iosf_mbi_assert_punit_acquired();
 
@@ -249,3 +249,15 @@ void vlv_flisdsi_write(struct drm_i915_private *i915, u32 reg, u32 val)
 	vlv_sideband_rw(i915, DPIO_DEVFN, IOSF_PORT_FLISDSI, SB_CRWRDA_NP,
 			reg, &val);
 }
+
+void vlv_iosf_sb_init(struct drm_i915_private *i915)
+{
+	if (IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915))
+		mutex_init(&i915->vlv_iosf_sb.lock);
+}
+
+void vlv_iosf_sb_fini(struct drm_i915_private *i915)
+{
+	if (IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915))
+		mutex_destroy(&i915->vlv_iosf_sb.lock);
+}

drivers/gpu/drm/i915/vlv_sideband.h

@@ -25,6 +25,9 @@ enum {
 	VLV_IOSF_SB_PUNIT,
 };
 
+void vlv_iosf_sb_init(struct drm_i915_private *i915);
+void vlv_iosf_sb_fini(struct drm_i915_private *i915);
+
 void vlv_iosf_sb_get(struct drm_i915_private *i915, unsigned long ports);
 void vlv_iosf_sb_put(struct drm_i915_private *i915, unsigned long ports);