[PATCH v11 10/24] coresight: etm4x: allow etm4x to be built as a module

Tingwei Zhang
2020-09-15T10:51:48Z

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

Allow to build coresight-etm4x 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-etm4x by the Makefile
- add an etm4_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>
Tested-by: Mike Leach <mike.leach@linaro.org>
Suggested-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
drivers/hwtracing/coresight/Kconfig | 5 +-
drivers/hwtracing/coresight/Makefile | 4 +-
...resight-etm4x.c => coresight-etm4x-core.c} | 84 ++++++++++++++-----
3 files changed, 69 insertions(+), 24 deletions(-)
rename drivers/hwtracing/coresight/{coresight-etm4x.c => coresight-etm4x-core.c} (96%)

diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
index 8fd9fd139cf3..d6e107bbd30b 100644
--- a/drivers/hwtracing/coresight/Kconfig
+++ b/drivers/hwtracing/coresight/Kconfig
@@ -78,7 +78,7 @@ config CORESIGHT_SOURCE_ETM3X
module will be called coresight-etm3x.

config CORESIGHT_SOURCE_ETM4X
- bool "CoreSight Embedded Trace Macrocell 4.x driver"
+ tristate "CoreSight Embedded Trace Macrocell 4.x driver"
depends on ARM64
select CORESIGHT_LINKS_AND_SINKS
select PID_IN_CONTEXTIDR
@@ -88,6 +88,9 @@ config CORESIGHT_SOURCE_ETM4X
for instruction level tracing. Depending on the implemented version
data tracing may also be available.

+ To compile this driver as a module, choose M here: the
+ module will be called coresight-etm4x.
+
config CORESIGHT_STM
tristate "CoreSight System Trace Macrocell driver"
depends on (ARM && !(CPU_32v3 || CPU_32v4 || CPU_32v4T)) || ARM64
diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
index 86b4648844b4..3f2b057443fb 100644
--- a/drivers/hwtracing/coresight/Makefile
+++ b/drivers/hwtracing/coresight/Makefile
@@ -14,8 +14,8 @@ obj-$(CONFIG_CORESIGHT_LINKS_AND_SINKS) += coresight-funnel.o \
obj-$(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_SOURCE_ETM4X) += coresight-etm4x.o
+coresight-etm4x-y := coresight-etm4x-core.o coresight-etm4x-sysfs.o
obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
obj-$(CONFIG_CORESIGHT_CPU_DEBUG) += coresight-cpu-debug.o
obj-$(CONFIG_CORESIGHT_CATU) += coresight-catu.o
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
similarity index 96%
rename from drivers/hwtracing/coresight/coresight-etm4x.c
rename to drivers/hwtracing/coresight/coresight-etm4x-core.c
index b29ad4f7fac2..33eb2b1508c6 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -1441,7 +1441,7 @@ static int __init etm4_pm_setup(void)
return ret;
}

-static void __init etm4_pm_clear(void)
+static void etm4_pm_clear(void)
{
cpu_pm_unregister_notifier(&etm4_cpu_pm_nb);
cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
@@ -1498,25 +1498,20 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
if (!desc.name)
return -ENOMEM;

- etmdrvdata[drvdata->cpu] = drvdata;
-
if (smp_call_function_single(drvdata->cpu,
etm4_init_arch_data, drvdata, 1))
dev_err(dev, "ETM arch init failed\n");

- if (etm4_arch_supported(drvdata->arch) == false) {
- ret = -EINVAL;
- goto err_arch_supported;
- }
+ if (etm4_arch_supported(drvdata->arch) == false)
+ return -EINVAL;

etm4_init_trace_id(drvdata);
etm4_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;
@@ -1526,17 +1521,17 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
desc.dev = dev;
desc.groups = coresight_etmv4_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, "CPU%d: ETM v%d.%d initialized\n",
drvdata->cpu, drvdata->arch >> 4, drvdata->arch & 0xf);
@@ -1547,10 +1542,6 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
}

return 0;
-
-err_arch_supported:
- etmdrvdata[drvdata->cpu] = NULL;
- return ret;
}

static struct amba_cs_uci_id uci_id_etm4[] = {
@@ -1562,6 +1553,40 @@ static struct amba_cs_uci_id uci_id_etm4[] = {
}
};

+static void __exit clear_etmdrvdata(void *info)
+{
+ int cpu = *(int *)info;
+
+ etmdrvdata[cpu] = NULL;
+}
+
+static int __exit etm4_remove(struct amba_device *adev)
+{
+ struct etmv4_drvdata *drvdata = dev_get_drvdata(&adev->dev);
+
+ etm_perf_symlink(drvdata->csdev, false);
+
+ /*
+ * Taking hotplug lock here to avoid racing between etm4_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;
+}
+
static const struct amba_id etm4_ids[] = {
CS_AMBA_ID(0x000bb95d), /* Cortex-A53 */
CS_AMBA_ID(0x000bb95e), /* Cortex-A57 */
@@ -1581,12 +1606,16 @@ static const struct amba_id etm4_ids[] = {
{},
};

+MODULE_DEVICE_TABLE(amba, etm4_ids);
+
static struct amba_driver etm4x_driver = {
.drv = {
.name = "coresight-etm4x",
+ .owner = THIS_MODULE,
.suppress_bind_attrs = true,
},
.probe = etm4_probe,
+ .remove = etm4_remove,
.id_table = etm4_ids,
};

@@ -1608,4 +1637,17 @@ static int __init etm4x_init(void)

return ret;
}
-device_initcall(etm4x_init);
+
+static void __exit etm4x_exit(void)
+{
+ amba_driver_unregister(&etm4x_driver);
+ etm4_pm_clear();
+}
+
+module_init(etm4x_init);
+module_exit(etm4x_exit);
+
+MODULE_AUTHOR("Pratik Patel <pratikp@codeaurora.org>");
+MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");
+MODULE_DESCRIPTION("Arm CoreSight Program Flow Trace v4.x driver");
+MODULE_LICENSE("GPL v2");