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

Mathieu Poirier
2020-09-15T18:35:48Z

On Tue, Sep 15, 2020 at 06:41:01PM +0800, Tingwei Zhang wrote:
> 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);

Indentation problem.

> +
> + 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();

Locking is no longer needed.

> - 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 */

Copy/paste error --> s/etm_pm_setup/etm_hp_setup

> + 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");
> --
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