intel_th: Add switch triggering support

Add support for asserting window switch trigger when tracing to MSU output
ports. This allows for software controlled switching between windows of
the MSU buffer, which can be used for double buffering while exporting the
trace data further from the MSU.

Signed-off-by: Alexander Shishkin <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/hwtracing/intel_th/core.c

···
 		.nres	= 1,
 		.res	= {
 			{
-				/* Handle TSCU from GTH driver */
+				/* Handle TSCU and CTS from GTH driver */
 				.start	= REG_GTH_OFFSET,
-				.end	= REG_TSCU_OFFSET + REG_TSCU_LENGTH - 1,
+				.end	= REG_CTS_OFFSET + REG_CTS_LENGTH - 1,
 				.flags	= IORESOURCE_MEM,
 			},
 		},
···
 	return 0;
 }
 EXPORT_SYMBOL_GPL(intel_th_trace_enable);
+
+/**
+ * intel_th_trace_switch() - execute a switch sequence
+ * @thdev:	output device that requests tracing switch
+ */
+int intel_th_trace_switch(struct intel_th_device *thdev)
+{
+	struct intel_th_device *hub = to_intel_th_device(thdev->dev.parent);
+	struct intel_th_driver *hubdrv = to_intel_th_driver(hub->dev.driver);
+
+	if (WARN_ON_ONCE(hub->type != INTEL_TH_SWITCH))
+		return -EINVAL;
+
+	if (WARN_ON_ONCE(thdev->type != INTEL_TH_OUTPUT))
+		return -EINVAL;
+
+	hubdrv->trig_switch(hub, &thdev->output);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(intel_th_trace_switch);
 
 /**
  * intel_th_trace_disable() - disable tracing for an output device

drivers/hwtracing/intel_th/gth.c

···
 	iowrite32(0, gth->base + REG_GTH_SCR);
 	iowrite32(0xfc, gth->base + REG_GTH_SCR2);
 
+	/* setup CTS for single trigger */
+	iowrite32(CTS_EVENT_ENABLE_IF_ANYTHING, gth->base + REG_CTS_C0S0_EN);
+	iowrite32(CTS_ACTION_CONTROL_SET_STATE(CTS_STATE_IDLE) |
+		  CTS_ACTION_CONTROL_TRIGGER, gth->base + REG_CTS_C0S0_ACT);
+
 	return 0;
 }
 
···
 }
 
 /**
+ * intel_th_gth_switch() - execute a switch sequence
+ * @thdev:	GTH device
+ * @output:	output device's descriptor
+ *
+ * This will execute a switch sequence that will trigger a switch window
+ * when tracing to MSC in multi-block mode.
+ */
+static void intel_th_gth_switch(struct intel_th_device *thdev,
+				struct intel_th_output *output)
+{
+	struct gth_device *gth = dev_get_drvdata(&thdev->dev);
+	unsigned long count;
+	u32 reg;
+
+	/* trigger */
+	iowrite32(0, gth->base + REG_CTS_CTL);
+	iowrite32(CTS_CTL_SEQUENCER_ENABLE, gth->base + REG_CTS_CTL);
+	/* wait on trigger status */
+	for (reg = 0, count = CTS_TRIG_WAITLOOP_DEPTH;
+	     count && !(reg & BIT(4)); count--) {
+		reg = ioread32(gth->base + REG_CTS_STAT);
+		cpu_relax();
+	}
+	if (!count)
+		dev_dbg(&thdev->dev, "timeout waiting for CTS Trigger\n");
+
+	intel_th_gth_stop(gth, output, false);
+	intel_th_gth_start(gth, output);
+}
+
+/**
  * intel_th_gth_assign() - assign output device to a GTH output port
  * @thdev:	GTH device
  * @othdev:	output device
···
 	.unassign	= intel_th_gth_unassign,
 	.set_output	= intel_th_gth_set_output,
 	.enable		= intel_th_gth_enable,
+	.trig_switch	= intel_th_gth_switch,
 	.disable	= intel_th_gth_disable,
 	.driver	= {
 		.name	= "gth",

drivers/hwtracing/intel_th/gth.h

···
 	REG_GTH_SCRPD3		= 0xec, /* ScratchPad[3] */
 	REG_TSCU_TSUCTRL	= 0x2000, /* TSCU control register */
 	REG_TSCU_TSCUSTAT	= 0x2004, /* TSCU status register */
+
+	/* Common Capture Sequencer (CTS) registers */
+	REG_CTS_C0S0_EN		= 0x30c0, /* clause_event_enable_c0s0 */
+	REG_CTS_C0S0_ACT	= 0x3180, /* clause_action_control_c0s0 */
+	REG_CTS_STAT		= 0x32a0, /* cts_status */
+	REG_CTS_CTL		= 0x32a4, /* cts_control */
 };
 
 /* waiting for Pipeline Empty bit(s) to assert for GTH */
···
 
 #define TSUCTRL_CTCRESYNC	BIT(0)
 #define TSCUSTAT_CTCSYNCING	BIT(1)
+
+/* waiting for Trigger status to assert for CTS */
+#define CTS_TRIG_WAITLOOP_DEPTH	10000
+
+#define CTS_EVENT_ENABLE_IF_ANYTHING	BIT(31)
+#define CTS_ACTION_CONTROL_STATE_OFF	27
+#define CTS_ACTION_CONTROL_SET_STATE(x)	\
+	(((x) & 0x1f) << CTS_ACTION_CONTROL_STATE_OFF)
+#define CTS_ACTION_CONTROL_TRIGGER	BIT(4)
+
+#define CTS_STATE_IDLE			0x10u
+
+#define CTS_CTL_SEQUENCER_ENABLE	BIT(0)
 
 #endif /* __INTEL_TH_GTH_H__ */

drivers/hwtracing/intel_th/intel_th.h

···
 					    struct intel_th_device *othdev);
 	void			(*enable)(struct intel_th_device *thdev,
 					  struct intel_th_output *output);
+	void			(*trig_switch)(struct intel_th_device *thdev,
+					       struct intel_th_output *output);
 	void			(*disable)(struct intel_th_device *thdev,
 					   struct intel_th_output *output);
 	/* output ops */
···
 void intel_th_driver_unregister(struct intel_th_driver *thdrv);
 
 int intel_th_trace_enable(struct intel_th_device *thdev);
+int intel_th_trace_switch(struct intel_th_device *thdev);
 int intel_th_trace_disable(struct intel_th_device *thdev);
 int intel_th_set_output(struct intel_th_device *thdev,
 			unsigned int master);
···
 	/* Timestamp counter unit (TSCU) */
 	REG_TSCU_OFFSET		= 0x2000,
 	REG_TSCU_LENGTH		= 0x1000,
+
+	REG_CTS_OFFSET		= 0x3000,
+	REG_CTS_LENGTH		= 0x1000,
 
 	/* Software Trace Hub (STH) [0x4000..0x4fff] */
 	REG_STH_OFFSET		= 0x4000,