coresight: etm4x: Allow etm4x to be built as a module

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>
Tested-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Kim Phillips <kim.phillips@arm.com>
Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200928163513.70169-11-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
index 8fd9fd139cf3f0cbd7f1b61a7e5e361de90d044d..d6e107bbd30b0ddf48843526c486d2d64be4249f 100644 (file)
--- 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 86b4648844b4fdceb65cb6349cbb5b46e891ef73..3f2b057443fb409d72d59fdc447b08ec42144cc2 100644 (file)
--- 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 f5ab13aaeceab7ae6bfae3cca5c8b8500debcd17..de76d57850bc5e24f8740d4a43caadda4012e26a 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -1447,7 +1447,7 @@ unregister_notifier:
        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);
@@ -1504,25 +1504,20 @@ 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;
@@ -1532,17 +1527,17 @@ 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);
@@ -1553,10 +1548,6 @@ 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[] = {
@@ -1568,6 +1559,40 @@ 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 */
@@ -1587,12 +1612,16 @@ 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,
 };
 
@@ -1614,4 +1643,17 @@ 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");