intel_th: Update scratchpad bits according to enabled output activity

Intel TH implements a scratchpad register to indicate to the firmware
and external debuggers what trace configuration is enabled so that
everybody plays nicely together. The register is a bit field and the
bit assignment convention is described in the developer's manual.

This patch enables the driver to automatically set scratchpad register
bits according to the output configuration that's enabled.

Based on work by Yann Fouassier.
Signed-off-by: Yann Fouassier <yann.fouassier@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/intel_th/core.c

@@ -319,6 +319,7 @@ static struct intel_th_subdevice {
 	unsigned		nres;
 	unsigned		type;
 	unsigned		otype;
+	unsigned		scrpd;
 	int			id;
 } intel_th_subdevices[TH_SUBDEVICE_MAX] = {
 	{
@@ -352,6 +353,7 @@ static struct intel_th_subdevice {
 		.id	= 0,
 		.type	= INTEL_TH_OUTPUT,
 		.otype	= GTH_MSU,
+		.scrpd	= SCRPD_MEM_IS_PRIM_DEST | SCRPD_MSC0_IS_ENABLED,
 	},
 	{
 		.nres	= 2,
@@ -371,6 +373,7 @@ static struct intel_th_subdevice {
 		.id	= 1,
 		.type	= INTEL_TH_OUTPUT,
 		.otype	= GTH_MSU,
+		.scrpd	= SCRPD_MEM_IS_PRIM_DEST | SCRPD_MSC1_IS_ENABLED,
 	},
 	{
 		.nres	= 2,
@@ -403,6 +406,7 @@ static struct intel_th_subdevice {
 		.name	= "pti",
 		.type	= INTEL_TH_OUTPUT,
 		.otype	= GTH_PTI,
+		.scrpd	= SCRPD_PTI_IS_PRIM_DEST,
 	},
 	{
 		.nres	= 1,
@@ -477,6 +481,7 @@ static int intel_th_populate(struct intel_th *th, struct resource *devres,
 			thdev->dev.devt = MKDEV(th->major, i);
 			thdev->output.type = subdev->otype;
 			thdev->output.port = -1;
+			thdev->output.scratchpad = subdev->scrpd;
 		}
 
 		err = device_add(&thdev->dev);

drivers/hwtracing/intel_th/gth.c

@@ -286,6 +286,10 @@ static int intel_th_gth_reset(struct gth_device *gth)
 	if (scratchpad & SCRPD_DEBUGGER_IN_USE)
 		return -EBUSY;
 
+	/* Always save/restore STH and TU registers in S0ix entry/exit */
+	scratchpad |= SCRPD_STH_IS_ENABLED | SCRPD_TRIGGER_IS_ENABLED;
+	iowrite32(scratchpad, gth->base + REG_GTH_SCRPD0);
+
 	/* output ports */
 	for (port = 0; port < 8; port++) {
 		if (gth_output_parm_get(gth, port, TH_OUTPUT_PARM(port)) ==
@@ -488,6 +492,10 @@ static void intel_th_gth_disable(struct intel_th_device *thdev,
 	if (!count)
 		dev_dbg(&thdev->dev, "timeout waiting for GTH[%d] PLE\n",
 			output->port);
+
+	reg = ioread32(gth->base + REG_GTH_SCRPD0);
+	reg &= ~output->scratchpad;
+	iowrite32(reg, gth->base + REG_GTH_SCRPD0);
 }
 
 /**
@@ -502,7 +510,7 @@ static void intel_th_gth_enable(struct intel_th_device *thdev,
 				struct intel_th_output *output)
 {
 	struct gth_device *gth = dev_get_drvdata(&thdev->dev);
-	u32 scr = 0xfc0000;
+	u32 scr = 0xfc0000, scrpd;
 	int master;
 
 	spin_lock(&gth->gth_lock);
@@ -517,6 +525,10 @@ static void intel_th_gth_enable(struct intel_th_device *thdev,
 	output->active = true;
 	spin_unlock(&gth->gth_lock);
 
+	scrpd = ioread32(gth->base + REG_GTH_SCRPD0);
+	scrpd |= output->scratchpad;
+	iowrite32(scrpd, gth->base + REG_GTH_SCRPD0);
+
 	iowrite32(scr, gth->base + REG_GTH_SCR);
 	iowrite32(0, gth->base + REG_GTH_SCR2);
 }

drivers/hwtracing/intel_th/gth.h

@@ -57,9 +57,6 @@ enum {
 	REG_GTH_SCRPD3		= 0xec, /* ScratchPad[3] */
 };
 
-/* Externall debugger is using Intel TH */
-#define SCRPD_DEBUGGER_IN_USE	BIT(24)
-
 /* waiting for Pipeline Empty bit(s) to assert for GTH */
 #define GTH_PLE_WAITLOOP_DEPTH	10000
 

drivers/hwtracing/intel_th/intel_th.h

@@ -30,6 +30,7 @@ enum {
  * struct intel_th_output - descriptor INTEL_TH_OUTPUT type devices
  * @port:	output port number, assigned by the switch
  * @type:	GTH_{MSU,CTP,PTI}
+ * @scratchpad:	scratchpad bits to flag when this output is enabled
  * @multiblock:	true for multiblock output configuration
  * @active:	true when this output is enabled
  *
@@ -41,6 +42,7 @@ enum {
 struct intel_th_output {
 	int		port;
 	unsigned int	type;
+	unsigned int	scratchpad;
 	bool		multiblock;
 	bool		active;
 };
@@ -241,4 +243,43 @@ enum {
 	GTH_PTI = 4,	/* MIPI-PTI */
 };
 
+/*
+ * Scratchpad bits: tell firmware and external debuggers
+ * what we are up to.
+ */
+enum {
+	/* Memory is the primary destination */
+	SCRPD_MEM_IS_PRIM_DEST		= BIT(0),
+	/* XHCI DbC is the primary destination */
+	SCRPD_DBC_IS_PRIM_DEST		= BIT(1),
+	/* PTI is the primary destination */
+	SCRPD_PTI_IS_PRIM_DEST		= BIT(2),
+	/* BSSB is the primary destination */
+	SCRPD_BSSB_IS_PRIM_DEST		= BIT(3),
+	/* PTI is the alternate destination */
+	SCRPD_PTI_IS_ALT_DEST		= BIT(4),
+	/* BSSB is the alternate destination */
+	SCRPD_BSSB_IS_ALT_DEST		= BIT(5),
+	/* DeepSx exit occurred */
+	SCRPD_DEEPSX_EXIT		= BIT(6),
+	/* S4 exit occurred */
+	SCRPD_S4_EXIT			= BIT(7),
+	/* S5 exit occurred */
+	SCRPD_S5_EXIT			= BIT(8),
+	/* MSU controller 0/1 is enabled */
+	SCRPD_MSC0_IS_ENABLED		= BIT(9),
+	SCRPD_MSC1_IS_ENABLED		= BIT(10),
+	/* Sx exit occurred */
+	SCRPD_SX_EXIT			= BIT(11),
+	/* Trigger Unit is enabled */
+	SCRPD_TRIGGER_IS_ENABLED	= BIT(12),
+	SCRPD_ODLA_IS_ENABLED		= BIT(13),
+	SCRPD_SOCHAP_IS_ENABLED		= BIT(14),
+	SCRPD_STH_IS_ENABLED		= BIT(15),
+	SCRPD_DCIH_IS_ENABLED		= BIT(16),
+	SCRPD_VER_IS_ENABLED		= BIT(17),
+	/* External debugger is using Intel TH */
+	SCRPD_DEBUGGER_IN_USE		= BIT(24),
+};
+
 #endif