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Message-ID: <CANLsYkwMmNFHUnJ-Qo9cGxbVG=1zT=26G9Jq+modve5s3shueg@mail.gmail.com>
Date: Thu, 7 Jun 2018 15:46:53 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Kim Phillips <kim.phillips@....com>
Cc: Leo Yan <leo.yan@...aro.org>,
Suzuki K Poulose <Suzuki.Poulose@....com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Alex Williamson <alex.williamson@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
David Howells <dhowells@...hat.com>,
Eric Auger <eric.auger@...hat.com>,
Eric Biederman <ebiederm@...ssion.com>,
Gargi Sharma <gs051095@...il.com>,
Geert Uytterhoeven <geert+renesas@...der.be>,
Kefeng Wang <wangkefeng.wang@...wei.com>,
Kirill Tkhai <ktkhai@...tuozzo.com>,
Mike Rapoport <rppt@...ux.vnet.ibm.com>,
Oleg Nesterov <oleg@...hat.com>,
Pavel Tatashin <pasha.tatashin@...cle.com>,
Rik van Riel <riel@...hat.com>,
Robin Murphy <robin.murphy@....com>,
Russell King <linux@...linux.org.uk>,
Thierry Reding <treding@...dia.com>,
Todd Kjos <tkjos@...gle.com>,
Randy Dunlap <rdunlap@...radead.org>,
linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 14/14] coresight: allow the coresight core driver to be
built as a module
On 5 June 2018 at 15:07, Kim Phillips <kim.phillips@....com> wrote:
> Allow to build coresight as a module. This enhances
> coresight developer efficiency by allowing the development to
> take place exclusively on the target, and without needing to
> reboot in between changes.
>
> - Kconfig becomes a tristate, to allow =m
> - append -core to source file name to allow module to
> be called coresight by the Makefile
> - modules can have only one init/exit, so we add the core bus
> register/unregister function calls to the etm_perf init/exit
> functions, since coresight.c does not have etm_pmu defined.
> - add a MODULE_DEVICE_TABLE for autoloading on boot
>
> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> Cc: Leo Yan <leo.yan@...aro.org>
> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Cc: Randy Dunlap <rdunlap@...radead.org>
> Cc: Suzuki K Poulose <Suzuki.Poulose@....com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Russell King <linux@...linux.org.uk>
> Signed-off-by: Kim Phillips <kim.phillips@....com>
> ---
> drivers/hwtracing/coresight/Kconfig | 5 ++++-
> drivers/hwtracing/coresight/Makefile | 7 +++++--
> .../coresight/{coresight.c => coresight-core.c} | 6 ------
> .../hwtracing/coresight/coresight-etm-perf.c | 17 ++++++++++++++++-
> 4 files changed, 25 insertions(+), 10 deletions(-)
> rename drivers/hwtracing/coresight/{coresight.c => coresight-core.c} (99%)
>
> diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
> index 181a44ea2d61..c05b265f7731 100644
> --- a/drivers/hwtracing/coresight/Kconfig
> +++ b/drivers/hwtracing/coresight/Kconfig
> @@ -2,7 +2,7 @@
> # Coresight configuration
> #
> menuconfig CORESIGHT
> - bool "CoreSight Tracing Support"
> + tristate "CoreSight Tracing Support"
> select ARM_AMBA
> select PERF_EVENTS
> help
> @@ -12,6 +12,9 @@ menuconfig CORESIGHT
> specification and configure the right series of components when a
> trace source gets enabled.
>
> + To compile this driver as a module, choose M here: the
> + module will be called coresight.
> +
> if CORESIGHT
> config CORESIGHT_LINKS_AND_SINKS
> tristate "CoreSight Link and Sink drivers"
> diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
> index 45d7a0f34170..ed2d4bcb017b 100644
> --- a/drivers/hwtracing/coresight/Makefile
> +++ b/drivers/hwtracing/coresight/Makefile
> @@ -2,8 +2,11 @@
> #
> # Makefile for CoreSight drivers.
> #
> -obj-$(CONFIG_CORESIGHT) += coresight.o coresight-etm-perf.o
> -obj-$(CONFIG_OF) += of_coresight.o
> +obj-$(CONFIG_CORESIGHT) += coresight.o
> +coresight-objs := coresight-core.o coresight-etm-perf.o
> +ifeq ($(CONFIG_OF), y)
> +coresight-objs += of_coresight.o
> +endif
> obj-$(CONFIG_CORESIGHT_LINK_AND_SINK_TMC) += coresight-tmc.o
> coresight-tmc-objs := coresight-tmc-core.o coresight-tmc-etf.o \
> coresight-tmc-etr.o
> diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight-core.c
> similarity index 99%
> rename from drivers/hwtracing/coresight/coresight.c
> rename to drivers/hwtracing/coresight/coresight-core.c
> index 1c941351f1d1..f96258de1e9b 100644
> --- a/drivers/hwtracing/coresight/coresight.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -948,12 +948,6 @@ struct bus_type coresight_bustype = {
> .name = "coresight",
> };
>
> -static int __init coresight_init(void)
> -{
> - return bus_register(&coresight_bustype);
> -}
> -postcore_initcall(coresight_init);
> -
> struct coresight_device *coresight_register(struct coresight_desc *desc)
> {
> int i;
> diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
> index 0fe7e43ea1c4..ceac9aee4a82 100644
> --- a/drivers/hwtracing/coresight/coresight-etm-perf.c
> +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
> @@ -472,6 +472,10 @@ static int __init etm_perf_init(void)
> {
> int ret;
>
> + ret = bus_register(&coresight_bustype);
> + if (ret)
> + return ret;
> +
> etm_pmu.capabilities = PERF_PMU_CAP_EXCLUSIVE;
>
> etm_pmu.attr_groups = etm_pmu_attr_groups;
> @@ -494,4 +498,15 @@ static int __init etm_perf_init(void)
>
> return ret;
> }
> -device_initcall(etm_perf_init);
> +postcore_initcall(etm_perf_init);
> +
> +static void __exit etm_perf_exit(void)
> +{
> + perf_pmu_unregister(&etm_pmu);
> + bus_unregister(&coresight_bustype);
> +}
> +module_exit(etm_perf_exit);
I see the perf functionality as an accessory to the core rather than
the other way around. Initialisation in the core code should be
driving the PMU registration.
> +
> +MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@...aro.org>");
> +MODULE_DESCRIPTION("Arm CoreSight tracer driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.17.0
>
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