[PATCH v11 09/24] coresight: etm3x: allow etm3x to be built as a module

Tingwei Zhang
2020-09-15T10:44:40Z

From: Kim Phillips <kim.phillips@arm.com>

Allow to build coresight-etm3x as a module, for ease of development.

- Kconfig becomes a tristate, to allow =m
- append -core to source file name to allow module to
be called coresight-etm3x by the Makefile
- add an etm_remove function, for module unload
- add a MODULE_DEVICE_TABLE for autoloading on boot
- delay advertising the per-cpu etmdrvdata
- protect etmdrvdata[] by modifying it on relevant CPU

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Suzuki K Poulose <Suzuki.Poulose@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Kim Phillips <kim.phillips@arm.com>
Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
---
drivers/hwtracing/coresight/Kconfig | 5 +-
drivers/hwtracing/coresight/Makefile | 5 +-
...resight-etm3x.c => coresight-etm3x-core.c} | 148 ++++++++++++++----
3 files changed, 122 insertions(+), 36 deletions(-)
rename drivers/hwtracing/coresight/{coresight-etm3x.c => coresight-etm3x-core.c} (90%)

diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
index 6433f835fc97..8fd9fd139cf3 100644
--- a/drivers/hwtracing/coresight/Kconfig
+++ b/drivers/hwtracing/coresight/Kconfig
@@ -65,7 +65,7 @@ config CORESIGHT_SINK_ETBV10
special enhancement or added features.

config CORESIGHT_SOURCE_ETM3X
- bool "CoreSight Embedded Trace Macrocell 3.x driver"
+ tristate "CoreSight Embedded Trace Macrocell 3.x driver"
depends on !ARM64
select CORESIGHT_LINKS_AND_SINKS
help
@@ -74,6 +74,9 @@ config CORESIGHT_SOURCE_ETM3X
This is primarily useful for instruction level tracing. Depending
the ETM version data tracing may also be available.

+ To compile this driver as a module, choose M here: the
+ module will be called coresight-etm3x.
+
config CORESIGHT_SOURCE_ETM4X
bool "CoreSight Embedded Trace Macrocell 4.x driver"
depends on ARM64
diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
index 19497d1d92bf..86b4648844b4 100644
--- a/drivers/hwtracing/coresight/Makefile
+++ b/drivers/hwtracing/coresight/Makefile
@@ -11,8 +11,9 @@ obj-$(CONFIG_CORESIGHT_SINK_TPIU) += coresight-tpiu.o
obj-$(CONFIG_CORESIGHT_SINK_ETBV10) += coresight-etb10.o
obj-$(CONFIG_CORESIGHT_LINKS_AND_SINKS) += coresight-funnel.o \
coresight-replicator.o
-obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o coresight-etm-cp14.o \
- coresight-etm3x-sysfs.o
+obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o
+coresight-etm3x-y := coresight-etm3x-core.o coresight-etm-cp14.o \
+ coresight-etm3x-sysfs.o
obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o \
coresight-etm4x-sysfs.o
obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c
similarity index 90%
rename from drivers/hwtracing/coresight/coresight-etm3x.c
rename to drivers/hwtracing/coresight/coresight-etm3x-core.c
index bf22dcfd3327..56eba0b5c71f 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c
@@ -782,6 +782,42 @@ static void etm_init_trace_id(struct etm_drvdata *drvdata)
drvdata->traceid = coresight_get_trace_id(drvdata->cpu);
}

+static int __init etm_hp_setup(void)
+{
+ int ret;
+
+ ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING,
+ "arm/coresight:starting",
+ etm_starting_cpu, etm_dying_cpu);
+
+ if (ret)
+ return ret;
+
+ ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN,
+ "arm/coresight:online",
+ etm_online_cpu, NULL);
+
+ /* HP dyn state ID returned in ret on success */
+ if (ret > 0) {
+ hp_online = ret;
+ return 0;
+ }
+
+ /* failed dyn state - remove others */
+ cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
+
+ return ret;
+}
+
+static void etm_hp_clear(void)
+{
+ cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
+ if (hp_online) {
+ cpuhp_remove_state_nocalls(hp_online);
+ hp_online = 0;
+ }
+}
+
static int etm_probe(struct amba_device *adev, const struct amba_id *id)
{
int ret;
@@ -824,38 +860,23 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
return -ENOMEM;

cpus_read_lock();
- etmdrvdata[drvdata->cpu] = drvdata;

if (smp_call_function_single(drvdata->cpu,
etm_init_arch_data, drvdata, 1))
dev_err(dev, "ETM arch init failed\n");

- if (!etm_count++) {
- cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING,
- "arm/coresight:starting",
- etm_starting_cpu, etm_dying_cpu);
- ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN,
- "arm/coresight:online",
- etm_online_cpu, NULL);
- if (ret < 0)
- goto err_arch_supported;
- hp_online = ret;
- }
cpus_read_unlock();

- if (etm_arch_supported(drvdata->arch) == false) {
- ret = -EINVAL;
- goto err_arch_supported;
- }
+ if (etm_arch_supported(drvdata->arch) == false)
+ return -EINVAL;

etm_init_trace_id(drvdata);
etm_set_default(&drvdata->config);

pdata = coresight_get_platform_data(dev);
- if (IS_ERR(pdata)) {
- ret = PTR_ERR(pdata);
- goto err_arch_supported;
- }
+ if (IS_ERR(pdata))
+ return PTR_ERR(pdata);
+
adev->dev.platform_data = pdata;

desc.type = CORESIGHT_DEV_TYPE_SOURCE;
@@ -865,17 +886,17 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
desc.dev = dev;
desc.groups = coresight_etm_groups;
drvdata->csdev = coresight_register(&desc);
- if (IS_ERR(drvdata->csdev)) {
- ret = PTR_ERR(drvdata->csdev);
- goto err_arch_supported;
- }
+ if (IS_ERR(drvdata->csdev))
+ return PTR_ERR(drvdata->csdev);

ret = etm_perf_symlink(drvdata->csdev, true);
if (ret) {
coresight_unregister(drvdata->csdev);
- goto err_arch_supported;
+ return ret;
}

+ etmdrvdata[drvdata->cpu] = drvdata;
+
pm_runtime_put(&adev->dev);
dev_info(&drvdata->csdev->dev,
"%s initialized\n", (char *)coresight_get_uci_data(id));
@@ -885,14 +906,40 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
}

return 0;
+}

-err_arch_supported:
- if (--etm_count == 0) {
- cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
- if (hp_online)
- cpuhp_remove_state_nocalls(hp_online);
- }
- return ret;
+static void __exit clear_etmdrvdata(void *info)
+{
+ int cpu = *(int *)info;
+
+ etmdrvdata[cpu] = NULL;
+}
+
+static int __exit etm_remove(struct amba_device *adev)
+{
+ struct etm_drvdata *drvdata = dev_get_drvdata(&adev->dev);
+
+ etm_perf_symlink(drvdata->csdev, false);
+
+ /*
+ * Taking hotplug lock here to avoid racing between etm_remove and
+ * CPU hotplug call backs.
+ */
+ cpus_read_lock();
+ /*
+ * The readers for etmdrvdata[] are CPU hotplug call backs
+ * and PM notification call backs. Change etmdrvdata[i] on
+ * CPU i ensures these call backs has consistent view
+ * inside one call back function.
+ */
+ if (smp_call_function_single(drvdata->cpu, clear_etmdrvdata, &drvdata->cpu, 1))
+ etmdrvdata[drvdata->cpu] = NULL;
+
+ cpus_read_unlock();
+
+ coresight_unregister(drvdata->csdev);
+
+ return 0;
}

#ifdef CONFIG_PM
@@ -937,6 +984,8 @@ static const struct amba_id etm_ids[] = {
{ 0, 0},
};

+MODULE_DEVICE_TABLE(amba, etm_ids);
+
static struct amba_driver etm_driver = {
.drv = {
.name = "coresight-etm3x",
@@ -945,6 +994,39 @@ static struct amba_driver etm_driver = {
.suppress_bind_attrs = true,
},
.probe = etm_probe,
+ .remove = etm_remove,
.id_table = etm_ids,
};
-builtin_amba_driver(etm_driver);
+
+static int __init etm_init(void)
+{
+ int ret;
+
+ ret = etm_hp_setup();
+
+ /* etm_pm_setup() does its own cleanup - exit on error */
+ if (ret)
+ return ret;
+
+ ret = amba_driver_register(&etm_driver);
+ if (ret) {
+ pr_err("Error registering etm3x driver\n");
+ etm_hp_clear();
+ }
+
+ return ret;
+}
+
+static void __exit etm_exit(void)
+{
+ amba_driver_unregister(&etm_driver);
+ etm_hp_clear();
+}
+
+module_init(etm_init);
+module_exit(etm_exit);
+
+MODULE_AUTHOR("Pratik Patel <pratikp@codeaurora.org>");
+MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");
+MODULE_DESCRIPTION("Arm CoreSight Program Flow Trace driver");
+MODULE_LICENSE("GPL v2");