Re: [PATCH v16 2/7] qcom-tgu: Add TGU driver
From: Songwei.Chai
Date: Thu Nov 05 2026 - 21:59:59 EST
On 11/5/2026 8:32 PM, Suzuki K Poulose wrote:
On 30/07/2026 09:06, Songwei Chai wrote:
Add driver to support device TGU (Trigger Generation Unit).
TGU is a Data Engine which can be utilized to sense a plurality of
signals and create a trigger into the CTI or generate interrupts to
processors. Add probe/enable/disable functions for tgu.
Signed-off-by: Songwei Chai <songwei.chai@xxxxxxxxxxxxxxxx>
Acked-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>
Reviewed-by: Jie Gan <jie.gan@xxxxxxxxxxxxxxxx>
---
.../ABI/testing/sysfs-bus-amba-devices-tgu | 9 +
MAINTAINERS | 11 +
drivers/Makefile | 1 +
drivers/hwtracing/Kconfig | 2 +
drivers/hwtracing/qcom/Kconfig | 20 ++
drivers/hwtracing/qcom/Makefile | 3 +
drivers/hwtracing/qcom/tgu.c | 192 ++++++++++++++++++
drivers/hwtracing/qcom/tgu.h | 51 +++++
8 files changed, 289 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-bus-amba-devices-tgu
create mode 100644 drivers/hwtracing/qcom/Kconfig
create mode 100644 drivers/hwtracing/qcom/Makefile
create mode 100644 drivers/hwtracing/qcom/tgu.c
create mode 100644 drivers/hwtracing/qcom/tgu.h
diff --git a/Documentation/ABI/testing/sysfs-bus-amba-devices-tgu b/Documentation/ABI/testing/sysfs-bus-amba-devices-tgu
new file mode 100644
index 000000000000..36ab64f1e301
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-amba-devices-tgu
@@ -0,0 +1,9 @@
+What: /sys/bus/amba/devices/<tgu-name>/enable_tgu
+Date: August 2026
+KernelVersion: 7.2
+Contact: Jinlong Mao <jinlong.mao@xxxxxxxxxxxxxxxx>, Songwei Chai <songwei.chai@xxxxxxxxxxxxxxxx>
+Description:
+ (RW) Set/Get the enable/disable status of TGU
+ Accepts only one of the 2 values - 0 or 1.
+ 0 : disable TGU.
+ 1 : enable TGU.
diff --git a/MAINTAINERS b/MAINTAINERS
index ce5c5185c773..4789321cca6d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22360,6 +22360,17 @@ S: Maintained
F: Documentation/tee/qtee.rst
F: drivers/tee/qcomtee/
+QUALCOMM HARDWARETRACING DRIVER
+M: Songwei Chai <songwei.chai@xxxxxxxxxxxxxxxx>
+M: Jie Gan <jie.gan@xxxxxxxxxxxxxxxx>
+M: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
+L: linux-arm-msm@xxxxxxxxxxxxxxx
+S: Maintained
+T: git git://git.kernel.org/pub/scm/linux/kernel/git/coresight/linux.git
+F: Documentation/ABI/testing/sysfs-bus-amba-devices-tgu
+F: Documentation/devicetree/bindings/arm/qcom,tgu.yaml
+F: drivers/hwtracing/qcom/
+
QUALCOMM TRUST ZONE MEMORY ALLOCATOR
M: Bartosz Golaszewski <brgl@xxxxxxxxxx>
L: linux-arm-msm@xxxxxxxxxxxxxxx
diff --git a/drivers/Makefile b/drivers/Makefile
index 0841ea851847..6a2cbe5b340f 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -176,6 +176,7 @@ obj-$(CONFIG_RAS) += ras/
obj-$(CONFIG_USB4) += thunderbolt/
obj-$(CONFIG_CORESIGHT) += hwtracing/coresight/
obj-y += hwtracing/intel_th/
+obj-y += hwtracing/qcom/
obj-$(CONFIG_STM) += hwtracing/stm/
obj-$(CONFIG_HISI_PTT) += hwtracing/ptt/
obj-y += android/
diff --git a/drivers/hwtracing/Kconfig b/drivers/hwtracing/Kconfig
index 911ee977103c..8a640218eed8 100644
--- a/drivers/hwtracing/Kconfig
+++ b/drivers/hwtracing/Kconfig
@@ -7,4 +7,6 @@ source "drivers/hwtracing/intel_th/Kconfig"
source "drivers/hwtracing/ptt/Kconfig"
+source "drivers/hwtracing/qcom/Kconfig"
+
endmenu
diff --git a/drivers/hwtracing/qcom/Kconfig b/drivers/hwtracing/qcom/Kconfig
new file mode 100644
index 000000000000..5c94c75ffa39
--- /dev/null
+++ b/drivers/hwtracing/qcom/Kconfig
@@ -0,0 +1,20 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# QCOM specific hwtracing drivers
+#
+menu "Qualcomm specific hwtracing drivers"
+
+config QCOM_TGU
+ tristate "QCOM Trigger Generation Unit driver"
+ depends on ARCH_QCOM || COMPILE_TEST
+ depends on ARM_AMBA
+ help
+ This driver provides support for Trigger Generation Unit that is
+ used to detect patterns or sequences on a given set of signals.
+ TGU is used to monitor a particular bus within a given region to
+ detect illegal transaction sequences or slave responses. It is also
+ used to monitor a data stream to detect protocol violations and to
+ provide a trigger point for centering data around a specific event
+ within the trace data buffer.
+
+endmenu
diff --git a/drivers/hwtracing/qcom/Makefile b/drivers/hwtracing/qcom/Makefile
new file mode 100644
index 000000000000..5a0a868c1ea0
--- /dev/null
+++ b/drivers/hwtracing/qcom/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_QCOM_TGU) += tgu.o
diff --git a/drivers/hwtracing/qcom/tgu.c b/drivers/hwtracing/qcom/tgu.c
new file mode 100644
index 000000000000..9c7dd4a09f02
--- /dev/null
+++ b/drivers/hwtracing/qcom/tgu.c
@@ -0,0 +1,192 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#include <linux/amba/bus.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/pm_runtime.h>
+
+#include "tgu.h"
+
+static void tgu_write_all_hw_regs(struct tgu_drvdata *drvdata)
+{
+ TGU_UNLOCK(drvdata->base);
+ /* Enable TGU to program the triggers */
+ writel(1, drvdata->base + TGU_CONTROL);
+ TGU_LOCK(drvdata->base);
+}
+
+static void tgu_enable(struct tgu_drvdata *drvdata)
+{
+ tgu_write_all_hw_regs(drvdata);
+ drvdata->enabled = true;
+}
+
+static void tgu_disable(struct tgu_drvdata *drvdata)
+{
+ TGU_UNLOCK(drvdata->base);
+ writel(0, drvdata->base + TGU_CONTROL);
+ TGU_LOCK(drvdata->base);
+
+ drvdata->enabled = false;
+}
+
+static ssize_t enable_tgu_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct tgu_drvdata *drvdata = dev_get_drvdata(dev);
+ bool enabled;
+
+ scoped_guard(mutex, &drvdata->lock)
+ enabled = drvdata->enabled;
+
+ return sysfs_emit(buf, "%d\n", enabled);
+}
+
+/* enable_tgu_store - Enable or disable the Trigger Generation Unit (TGU). */
+static ssize_t enable_tgu_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf,
+ size_t size)
+{
+ struct tgu_drvdata *drvdata = dev_get_drvdata(dev);
+ unsigned long val;
+ int ret;
+
+ ret = kstrtoul(buf, 0, &val);
+ if (ret || val > 1)
+ return -EINVAL;
+
+ /*
+ * Hold the mutex across the whole check-and-act sequence: the check of
+ * drvdata->enabled, the PM runtime reference counting and the state
+ * update must be atomic, otherwise concurrent writers could each
+ * imbalance the PM runtime usage counter.
+ */
+ guard(mutex)(&drvdata->lock);
+
+ if (val) {
+ if (drvdata->enabled)
+ return -EBUSY;
+
+ ret = pm_runtime_resume_and_get(dev);
+ if (ret)
+ return ret;
+
+ tgu_enable(drvdata);
+ } else {
+ if (!drvdata->enabled)
+ return -EINVAL;
+
+ tgu_disable(drvdata);
+ pm_runtime_put(dev);
+ }
+
+ return size;
+}
+static DEVICE_ATTR_RW(enable_tgu);
+
+static struct attribute *tgu_common_attrs[] = {
+ &dev_attr_enable_tgu.attr,
+ NULL,
+};
+
+static const struct attribute_group tgu_common_grp = {
+ .attrs = tgu_common_attrs,
+};
+
+static const struct attribute_group *tgu_attr_groups[] = {
+ &tgu_common_grp,
+ NULL,
+};
+
+static int tgu_probe(struct amba_device *adev, const struct amba_id *id)
+{
+ struct device *dev = &adev->dev;
+ struct tgu_drvdata *drvdata;
+ int ret;
+
+ drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
+ if (!drvdata)
+ return -ENOMEM;
+
+ drvdata->dev = &adev->dev;
+ dev_set_drvdata(dev, drvdata);
+
+ drvdata->base = devm_ioremap_resource(dev, &adev->res);
+ if (IS_ERR(drvdata->base))
+ return PTR_ERR(drvdata->base);
+
+ ret = devm_mutex_init(dev, &drvdata->lock);
+ if (ret)
+ return ret;
+
+ drvdata->enabled = false;
+
+ ret = sysfs_create_groups(&dev->kobj, tgu_attr_groups);
+ if (ret) {
+ dev_err(dev, "failed to create sysfs groups: %d\n", ret);
+ return ret;
+ }
+
+ pm_runtime_put(&adev->dev);
+
+ return 0;
+}
+
+static void tgu_remove(struct amba_device *adev)
+{
+ struct device *dev = &adev->dev;
+ struct tgu_drvdata *drvdata = dev_get_drvdata(dev);
+
+ sysfs_remove_groups(&dev->kobj, tgu_attr_groups);
+
+ /*
+ * If the device is still enabled through sysfs, disable the hardware
+ * and drop the PM runtime reference taken in enable_tgu_store() so the
+ * usage counter stays balanced. Use the synchronous put: the driver core
+ * disables runtime PM right after ->remove() returns, and the barrier in
+ * pm_runtime_disable() would cancel a still-queued async idle/suspend,
+ * leaving the runtime-PM state inconsistent.
+ */
+ scoped_guard(mutex, &drvdata->lock) {
+ if (drvdata->enabled) {
+ tgu_disable(drvdata);
+ pm_runtime_put_sync(dev);
+ }
+ }
+}
+
+static const struct amba_id tgu_ids[] = {
+ {
+ .id = 0x000f0e00,
+ .mask = 0x000fffff,
+ },
+ { 0, 0, NULL },
+};
+
+MODULE_DEVICE_TABLE(amba, tgu_ids);
+
+static struct amba_driver tgu_driver = {
+ .drv = {
+ .name = "qcom-tgu",
+ .suppress_bind_attrs = true,
+ },
+ .probe = tgu_probe,
+ .remove = tgu_remove,
+ .id_table = tgu_ids,
+};
+
+module_amba_driver(tgu_driver);
+
+MODULE_AUTHOR("Songwei Chai <songwei.chai@xxxxxxxxxxxxxxxx>");
+MODULE_AUTHOR("Jinlong Mao <jinlong.mao@xxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Qualcomm Trigger Generation Unit driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hwtracing/qcom/tgu.h b/drivers/hwtracing/qcom/tgu.h
new file mode 100644
index 000000000000..ebba49402a20
--- /dev/null
+++ b/drivers/hwtracing/qcom/tgu.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#ifndef _QCOM_TGU_H
+#define _QCOM_TGU_H
+
+/* Register addresses */
+#define TGU_CONTROL 0x0000
+#define TGU_LAR 0xfb0
+#define TGU_UNLOCK_OFFSET 0xc5acce55
+
+static inline void TGU_LOCK(void __iomem *addr)
+{
+ do {
+ /* Wait for things to settle */
+ mb();
+ writel_relaxed(0x0, addr + TGU_LAR);
+ } while (0);
+}
This is simply replicating the CS_LOCK/CS_UNLOCK.
I don't mind those (and relevant definitions) to be moved into include/linux/coresight.h and reused for your driver.
The rest looks fine by me.
Thanks Suzuki.
I will add a separate CoreSight API cleanuppatch to this series to move common definitions such as CS_LOCK/CS_UNLOCKfrom coresight-priv.hto include/linux/coresight.h, allowing them to be reused by the TGU driver.
Suzuki
+
+static inline void TGU_UNLOCK(void __iomem *addr)
+{
+ do {
+ writel_relaxed(TGU_UNLOCK_OFFSET, addr + TGU_LAR);
+ /* Make sure everyone has seen this */
+ mb();
+ } while (0);
+}
+
+/**
+ * struct tgu_drvdata - Data structure for a TGU (Trigger Generation Unit)
+ * @base: Memory-mapped base address of the TGU device
+ * @dev: Pointer to the associated device structure
+ * @lock: Mutex serialising enable/disable and the associated PM runtime
+ * reference counting against concurrent sysfs access
+ * @enabled: Flag indicating whether the TGU device is enabled
+ *
+ * This structure defines the data associated with a TGU device,
+ * including its base address, device pointer, the lock serialising
+ * enable/disable, and the enable status.
+ */
+struct tgu_drvdata {
+ void __iomem *base;
+ struct device *dev;
+ struct mutex lock;
+ bool enabled;
+};
+
+#endif