@@ -239,6 +239,7 @@ static ssize_t reset_store(struct device *dev,
 	for (i = 0; i < drvdata->nr_resource; i++)
 		config->res_ctrl[i] = 0x0;
 
+	config->ss_idx = 0x0;
 	for (i = 0; i < drvdata->nr_ss_cmp; i++) {
 		config->ss_ctrl[i] = 0x0;
 		config->ss_pe_cmp[i] = 0x0;

@@ -1717,6 +1718,123 @@ static ssize_t res_ctrl_store(struct device *dev,
 }
 static DEVICE_ATTR_RW(res_ctrl);
 
+static ssize_t sshot_idx_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	unsigned long val;
+	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	struct etmv4_config *config = &drvdata->config;
+
+	val = config->ss_idx;
+	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t sshot_idx_store(struct device *dev,
+			       struct device_attribute *attr,
+			       const char *buf, size_t size)
+{
+	unsigned long val;
+	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	struct etmv4_config *config = &drvdata->config;
+
+	if (kstrtoul(buf, 16, &val))
+		return -EINVAL;
+	if (val >= drvdata->nr_ss_cmp)
+		return -EINVAL;
+
+	spin_lock(&drvdata->spinlock);
+	config->ss_idx = val;
+	spin_unlock(&drvdata->spinlock);
+	return size;
+}
+static DEVICE_ATTR_RW(sshot_idx);
+
+static ssize_t sshot_ctrl_show(struct device *dev,
+			       struct device_attribute *attr,
+			       char *buf)
+{
+	unsigned long val;
+	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	struct etmv4_config *config = &drvdata->config;
+
+	spin_lock(&drvdata->spinlock);
+	val = config->ss_ctrl[config->ss_idx];
+	spin_unlock(&drvdata->spinlock);
+	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t sshot_ctrl_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t size)
+{
+	u8 idx;
+	unsigned long val;
+	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	struct etmv4_config *config = &drvdata->config;
+
+	if (kstrtoul(buf, 16, &val))
+		return -EINVAL;
+
+	spin_lock(&drvdata->spinlock);
+	idx = config->ss_idx;
+	config->ss_ctrl[idx] = val & GENMASK(24, 0);
+	/* must clear bit 31 in related status register on programming */
+	config->ss_status[idx] &= ~BIT(31);
+	spin_unlock(&drvdata->spinlock);
+	return size;
+}
+static DEVICE_ATTR_RW(sshot_ctrl);
+
+static ssize_t sshot_status_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	unsigned long val;
+	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	struct etmv4_config *config = &drvdata->config;
+
+	spin_lock(&drvdata->spinlock);
+	val = config->ss_status[config->ss_idx];
+	spin_unlock(&drvdata->spinlock);
+	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+static DEVICE_ATTR_RO(sshot_status);
+
+static ssize_t sshot_pe_ctrl_show(struct device *dev,
+				  struct device_attribute *attr,
+				  char *buf)
+{
+	unsigned long val;
+	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	struct etmv4_config *config = &drvdata->config;
+
+	spin_lock(&drvdata->spinlock);
+	val = config->ss_pe_cmp[config->ss_idx];
+	spin_unlock(&drvdata->spinlock);
+	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t sshot_pe_ctrl_store(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf, size_t size)
+{
+	u8 idx;
+	unsigned long val;
+	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	struct etmv4_config *config = &drvdata->config;
+
+	if (kstrtoul(buf, 16, &val))
+		return -EINVAL;
+
+	spin_lock(&drvdata->spinlock);
+	idx = config->ss_idx;
+	config->ss_pe_cmp[idx] = val & GENMASK(7, 0);
+	/* must clear bit 31 in related status register on programming */
+	config->ss_status[idx] &= ~BIT(31);
+	spin_unlock(&drvdata->spinlock);
+	return size;
+}
+static DEVICE_ATTR_RW(sshot_pe_ctrl);
+
 static ssize_t ctxid_idx_show(struct device *dev,
 			      struct device_attribute *attr,
 			      char *buf)

@@ -2173,6 +2291,10 @@ static struct attribute *coresight_etmv4_attrs[] = {
 	&dev_attr_addr_exlevel_s_ns.attr,
 	&dev_attr_addr_cmp_view.attr,
 	&dev_attr_vinst_pe_cmp_start_stop.attr,
+	&dev_attr_sshot_idx.attr,
+	&dev_attr_sshot_ctrl.attr,
+	&dev_attr_sshot_pe_ctrl.attr,
+	&dev_attr_sshot_status.attr,
 	&dev_attr_seq_idx.attr,
 	&dev_attr_seq_state.attr,
 	&dev_attr_seq_event.attr,

@@ -149,6 +149,9 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
 			       drvdata->base + TRCRSCTLRn(i));
 
 	for (i = 0; i < drvdata->nr_ss_cmp; i++) {
+		/* always clear status bit on restart if using single-shot */
+		if (config->ss_ctrl[i] || config->ss_pe_cmp[i])
+			config->ss_status[i] &= ~BIT(31);
 		writel_relaxed(config->ss_ctrl[i],
 			       drvdata->base + TRCSSCCRn(i));
 		writel_relaxed(config->ss_status[i],

@@ -448,6 +451,9 @@ static void etm4_disable_hw(void *info)
 {
 	u32 control;
 	struct etmv4_drvdata *drvdata = info;
+	struct etmv4_config *config = &drvdata->config;
+	struct device *etm_dev = &drvdata->csdev->dev;
+	int i;
 
 	CS_UNLOCK(drvdata->base);
 

@@ -470,6 +476,18 @@ static void etm4_disable_hw(void *info)
 	isb();
 	writel_relaxed(control, drvdata->base + TRCPRGCTLR);
 
+	/* wait for TRCSTATR.PMSTABLE to go to '1' */
+	if (coresight_timeout(drvdata->base, TRCSTATR,
+			      TRCSTATR_PMSTABLE_BIT, 1))
+		dev_err(etm_dev,
+			"timeout while waiting for PM stable Trace Status\n");
+
+	/* read the status of the single shot comparators */
+	for (i = 0; i < drvdata->nr_ss_cmp; i++) {
+		config->ss_status[i] =
+			readl_relaxed(drvdata->base + TRCSSCSRn(i));
+	}
+
 	coresight_disclaim_device_unlocked(drvdata->base);
 
 	CS_LOCK(drvdata->base);

@@ -576,6 +594,7 @@ static void etm4_init_arch_data(void *info)
 	u32 etmidr4;
 	u32 etmidr5;
 	struct etmv4_drvdata *drvdata = info;
+	int i;
 
 	/* Make sure all registers are accessible */
 	etm4_os_unlock(drvdata);

@@ -699,9 +718,14 @@ static void etm4_init_arch_data(void *info)
 	drvdata->nr_resource = BMVAL(etmidr4, 16, 19) + 1;
 	/*
 	 * NUMSSCC, bits[23:20] the number of single-shot
-	 * comparator control for tracing
+	 * comparator control for tracing. Read any status regs as these
+	 * also contain RO capability data.
 	 */
 	drvdata->nr_ss_cmp = BMVAL(etmidr4, 20, 23);
+	for (i = 0; i < drvdata->nr_ss_cmp; i++) {
+		drvdata->config.ss_status[i] =
+			readl_relaxed(drvdata->base + TRCSSCSRn(i));
+	}
 	/* NUMCIDC, bits[27:24] number of Context ID comparators for tracing */
 	drvdata->numcidc = BMVAL(etmidr4, 24, 27);
 	/* NUMVMIDC, bits[31:28] number of VMID comparators for tracing */

@@ -175,6 +175,7 @@
 					 ETM_MODE_EXCL_USER)
 
 #define TRCSTATR_IDLE_BIT		0
+#define TRCSTATR_PMSTABLE_BIT		1
 #define ETM_DEFAULT_ADDR_COMP		0
 
 /* PowerDown Control Register bits */

@@ -226,6 +227,7 @@
  * @cntr_val:	Sets or returns the value for a counter.
  * @res_idx:	Resource index selector.
  * @res_ctrl:	Controls the selection of the resources in the trace unit.
+ * @ss_idx:	Single-shot index selector.
  * @ss_ctrl:	Controls the corresponding single-shot comparator resource.
  * @ss_status:	The status of the corresponding single-shot comparator.
  * @ss_pe_cmp:	Selects the PE comparator inputs for Single-shot control.

@@ -269,6 +271,7 @@ struct etmv4_config {
 	u32				cntr_val[ETMv4_MAX_CNTR];
 	u8				res_idx;
 	u32				res_ctrl[ETM_MAX_RES_SEL];
+	u8				ss_idx;
 	u32				ss_ctrl[ETM_MAX_SS_CMP];
 	u32				ss_status[ETM_MAX_SS_CMP];
 	u32				ss_pe_cmp[ETM_MAX_SS_CMP];