coresight: tmc: Add shutdown callback for TMC ETR

Implement a shutdown callback to ensure ETR hardware is
properly shutdown in reboot/shutdown path. This is required
for ETR which has SMMU address translation enabled like on
SC7180 SoC and few others. If the hardware is still accessing
memory after SMMU translation is disabled as part of SMMU
shutdown callback in system reboot or shutdown path, then
IOVAs(I/O virtual address) which it was using will go on the
bus as the physical addresses which might result in unknown
crashes (NoC/interconnect errors). So we make sure from this
shutdown callback that the ETR is shutdown before SMMU translation
is disabled and device_link in SMMU driver will take care of
ordering of shutdown callbacks such that SMMU shutdown callback
is not called before any of its consumer shutdown callbacks.
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200716175746.3338735-13-mathieu.poirier@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/coresight/coresight-tmc-etr.c

@@ -1110,7 +1110,7 @@ static void __tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
 
 }
 
-static void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
+void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
 {
 	__tmc_etr_disable_hw(drvdata);
 	/* Disable CATU device if this ETR is connected to one */

drivers/hwtracing/coresight/coresight-tmc.c

@@ -538,6 +538,28 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
 	return ret;
 }
 
+static void tmc_shutdown(struct amba_device *adev)
+{
+	unsigned long flags;
+	struct tmc_drvdata *drvdata = amba_get_drvdata(adev);
+
+	spin_lock_irqsave(&drvdata->spinlock, flags);
+
+	if (drvdata->mode == CS_MODE_DISABLED)
+		goto out;
+
+	if (drvdata->config_type == TMC_CONFIG_TYPE_ETR)
+		tmc_etr_disable_hw(drvdata);
+
+	/*
+	 * We do not care about coresight unregister here unlike remove
+	 * callback which is required for making coresight modular since
+	 * the system is going down after this.
+	 */
+out:
+	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+}
+
 static const struct amba_id tmc_ids[] = {
 	CS_AMBA_ID(0x000bb961),
 	/* Coresight SoC 600 TMC-ETR/ETS */
@@ -556,6 +578,7 @@ static struct amba_driver tmc_driver = {
 		.suppress_bind_attrs = true,
 	},
 	.probe		= tmc_probe,
+	.shutdown	= tmc_shutdown,
 	.id_table	= tmc_ids,
 };
 builtin_amba_driver(tmc_driver);

drivers/hwtracing/coresight/coresight-tmc.h

@@ -268,6 +268,7 @@ ssize_t tmc_etb_get_sysfs_trace(struct tmc_drvdata *drvdata,
 /* ETR functions */
 int tmc_read_prepare_etr(struct tmc_drvdata *drvdata);
 int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata);
+void tmc_etr_disable_hw(struct tmc_drvdata *drvdata);
 extern const struct coresight_ops tmc_etr_cs_ops;
 ssize_t tmc_etr_get_sysfs_trace(struct tmc_drvdata *drvdata,
 				loff_t pos, size_t len, char **bufpp);