coresight-tpdm: Add support to configure CMB

TPDM CMB subunits support two forms of CMB data set element creation:
continuous and trace-on-change collection mode. Continuous change
creates CMB data set elements on every CMBCLK edge. Trace-on-change
creates CMB data set elements only when a new data set element differs
in value from the previous element in a CMB data set. Set CMB_CR.MODE
to 0 for continuous CMB collection mode. Set CMB_CR.MODE to 1 for
trace-on-change CMB collection mode.
Reviewed-by: James Clark <james.clark@arm.com>
Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
Signed-off-by: Jinlong Mao <quic_jinlmao@quicinc.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/1707024641-22460-7-git-send-email-quic_taozha@quicinc.com

Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm

@@ -170,3 +170,17 @@ Contact:	Jinlong Mao (QUIC) <quic_jinlmao@quicinc.com>, Tao Zhang (QUIC) <quic_t
 Description:
 		(RW) Set/Get the MSR(mux select register) for the DSB subunit
 		TPDM.
+
+What:		/sys/bus/coresight/devices/<tpdm-name>/cmb_mode
+Date:		January 2024
+KernelVersion	6.9
+Contact:	Jinlong Mao (QUIC) <quic_jinlmao@quicinc.com>, Tao Zhang (QUIC) <quic_taozha@quicinc.com>
+Description:	(Write) Set the data collection mode of CMB tpdm. Continuous
+		change creates CMB data set elements on every CMBCLK edge.
+		Trace-on-change creates CMB data set elements only when a new
+		data set element differs in value from the previous element
+		in a CMB data set.
+
+		Accepts only one of the 2 values -  0 or 1.
+		0 : Continuous CMB collection mode.
+		1 : Trace-on-change CMB collection mode.

drivers/hwtracing/coresight/coresight-tpdm.c

@@ -137,6 +137,18 @@ static umode_t tpdm_dsb_is_visible(struct kobject *kobj,
 	return 0;
 }
 
+static umode_t tpdm_cmb_is_visible(struct kobject *kobj,
+				   struct attribute *attr, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+	if (drvdata && tpdm_has_cmb_dataset(drvdata))
+		return attr->mode;
+
+	return 0;
+}
+
 static umode_t tpdm_dsb_msr_is_visible(struct kobject *kobj,
 				       struct attribute *attr, int n)
 {
@@ -161,6 +173,9 @@ static void tpdm_reset_datasets(struct tpdm_drvdata *drvdata)
 		drvdata->dsb->trig_ts = true;
 		drvdata->dsb->trig_type = false;
 	}
+
+	if (drvdata->cmb)
+		memset(drvdata->cmb, 0, sizeof(struct cmb_dataset));
 }
 
 static void set_dsb_mode(struct tpdm_drvdata *drvdata, u32 *val)
@@ -391,6 +406,12 @@ static int tpdm_datasets_setup(struct tpdm_drvdata *drvdata)
 		if (!drvdata->dsb)
 			return -ENOMEM;
 	}
+	if (tpdm_has_cmb_dataset(drvdata) && (!drvdata->cmb)) {
+		drvdata->cmb = devm_kzalloc(drvdata->dev,
+						sizeof(*drvdata->cmb), GFP_KERNEL);
+		if (!drvdata->cmb)
+			return -ENOMEM;
+	}
 	tpdm_reset_datasets(drvdata);
 
 	return 0;
@@ -729,6 +750,34 @@ static ssize_t dsb_trig_ts_store(struct device *dev,
 }
 static DEVICE_ATTR_RW(dsb_trig_ts);
 
+static ssize_t cmb_mode_show(struct device *dev,
+			     struct device_attribute *attr,
+			     char *buf)
+{
+	struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+	return sysfs_emit(buf, "%x\n", drvdata->cmb->trace_mode);
+
+}
+
+static ssize_t cmb_mode_store(struct device *dev,
+			      struct device_attribute *attr,
+			      const char *buf,
+			      size_t size)
+{
+	struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	unsigned long trace_mode;
+
+	if (kstrtoul(buf, 0, &trace_mode) || (trace_mode & ~1UL))
+		return -EINVAL;
+
+	spin_lock(&drvdata->spinlock);
+	drvdata->cmb->trace_mode = trace_mode;
+	spin_unlock(&drvdata->spinlock);
+	return size;
+}
+static DEVICE_ATTR_RW(cmb_mode);
+
 static struct attribute *tpdm_dsb_edge_attrs[] = {
 	&dev_attr_ctrl_idx.attr,
 	&dev_attr_ctrl_val.attr,
@@ -845,6 +894,11 @@ static struct attribute *tpdm_dsb_attrs[] = {
 	NULL,
 };
 
+static struct attribute *tpdm_cmb_attrs[] = {
+	&dev_attr_cmb_mode.attr,
+	NULL,
+};
+
 static struct attribute_group tpdm_dsb_attr_grp = {
 	.attrs = tpdm_dsb_attrs,
 	.is_visible = tpdm_dsb_is_visible,
@@ -874,6 +928,11 @@ static struct attribute_group tpdm_dsb_msr_grp = {
 	.name = "dsb_msr",
 };
 
+static struct attribute_group tpdm_cmb_attr_grp = {
+	.attrs = tpdm_cmb_attrs,
+	.is_visible = tpdm_cmb_is_visible,
+};
+
 static const struct attribute_group *tpdm_attr_grps[] = {
 	&tpdm_attr_grp,
 	&tpdm_dsb_attr_grp,
@@ -881,6 +940,7 @@ static const struct attribute_group *tpdm_attr_grps[] = {
 	&tpdm_dsb_trig_patt_grp,
 	&tpdm_dsb_patt_grp,
 	&tpdm_dsb_msr_grp,
+	&tpdm_cmb_attr_grp,
 	NULL,
 };
 

drivers/hwtracing/coresight/coresight-tpdm.h

@@ -14,6 +14,8 @@
 
 /* Enable bit for CMB subunit */
 #define TPDM_CMB_CR_ENA		BIT(0)
+/* Trace collection mode for CMB subunit */
+#define TPDM_CMB_CR_MODE	BIT(1)
 
 /* DSB Subunit Registers */
 #define TPDM_DSB_CR		(0x780)
@@ -181,6 +183,14 @@ struct dsb_dataset {
 	bool			trig_type;
 };
 
+/**
+ * struct cmb_dataset
+ * @trace_mode:       Dataset collection mode
+ */
+struct cmb_dataset {
+	u32			trace_mode;
+};
+
 /**
  * struct tpdm_drvdata - specifics associated to an TPDM component
  * @base:       memory mapped base address for this component.
@@ -190,6 +200,7 @@ struct dsb_dataset {
  * @enable:     enable status of the component.
  * @datasets:   The datasets types present of the TPDM.
  * @dsb         Specifics associated to TPDM DSB.
+ * @cmb         Specifics associated to TPDM CMB.
  * @dsb_msr_num Number of MSR supported by DSB TPDM
  */
 
@@ -201,6 +212,7 @@ struct tpdm_drvdata {
 	bool			enable;
 	unsigned long		datasets;
 	struct dsb_dataset	*dsb;
+	struct cmb_dataset	*cmb;
 	u32			dsb_msr_num;
 };