From mboxrd@z Thu Jan 1 00:00:00 1970 From: Winiarska, Iwona Date: Mon, 15 Nov 2021 22:19:04 +0000 Subject: [PATCH v2 09/15] peci: Add sysfs interface for PECI bus In-Reply-To: References: <20210803113134.2262882-1-iwona.winiarska@intel.com> <20210803113134.2262882-10-iwona.winiarska@intel.com> Message-ID: <0fb36e270cd497ade90eb0a4e9882819af3472dd.camel@intel.com> List-Id: To: linux-aspeed@lists.ozlabs.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Fri, 2021-08-27 at 12:11 -0700, Dan Williams wrote: > On Tue, Aug 3, 2021 at 4:35 AM Iwona Winiarska > wrote: > > > > PECI devices may not be discoverable at the time when PECI controller is > > being added (e.g. BMC can boot up when the Host system is still in S5). > > Since we currently don't have the capabilities to figure out the Host > > system state inside the PECI subsystem itself, we have to rely on > > userspace to do it for us. > > > > In the future, PECI subsystem may be expanded with mechanisms that allow > > us to avoid depending on userspace interaction (e.g. CPU presence could > > be detected using GPIO, and the information on whether it's discoverable > > could be obtained over IPMI). > > Thanks for this detail. > > > Unfortunately, those methods may ultimately not be available (support > > will vary from platform to platform), which means that we still need > > platform independent method triggered by userspace. > > > > Signed-off-by: Iwona Winiarska > > --- > > ?Documentation/ABI/testing/sysfs-bus-peci | 16 +++++ > > ?drivers/peci/Makefile??????????????????? |? 2 +- > > ?drivers/peci/core.c????????????????????? |? 3 +- > > ?drivers/peci/device.c??????????????????? |? 1 + > > ?drivers/peci/internal.h????????????????? |? 5 ++ > > ?drivers/peci/sysfs.c???????????????????? | 82 ++++++++++++++++++++++++ > > ?6 files changed, 107 insertions(+), 2 deletions(-) > > ?create mode 100644 Documentation/ABI/testing/sysfs-bus-peci > > ?create mode 100644 drivers/peci/sysfs.c > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-peci > > b/Documentation/ABI/testing/sysfs-bus-peci > > new file mode 100644 > > index 000000000000..56c2b2216bbd > > --- /dev/null > > +++ b/Documentation/ABI/testing/sysfs-bus-peci > > @@ -0,0 +1,16 @@ > > +What:????????? /sys/bus/peci/rescan > > +Date:????????? July 2021 > > +KernelVersion: 5.15 > > +Contact:?????? Iwona Winiarska > > +Description: > > +?????????????? Writing a non-zero value to this attribute will > > +?????????????? initiate scan for PECI devices on all PECI controllers > > +?????????????? in the system. > > + > > +What:????????? /sys/bus/peci/devices/-/remove > > +Date:????????? July 2021 > > +KernelVersion: 5.15 > > +Contact:?????? Iwona Winiarska > > +Description: > > +?????????????? Writing a non-zero value to this attribute will > > +?????????????? remove the PECI device and any of its children. > > diff --git a/drivers/peci/Makefile b/drivers/peci/Makefile > > index c5f9d3fe21bb..917f689e147a 100644 > > --- a/drivers/peci/Makefile > > +++ b/drivers/peci/Makefile > > @@ -1,7 +1,7 @@ > > ?# SPDX-License-Identifier: GPL-2.0-only > > > > ?# Core functionality > > -peci-y := core.o request.o device.o > > +peci-y := core.o request.o device.o sysfs.o > > ?obj-$(CONFIG_PECI) += peci.o > > > > ?# Hardware specific bus drivers > > diff --git a/drivers/peci/core.c b/drivers/peci/core.c > > index d143f1a7fe98..c473acb3c2a0 100644 > > --- a/drivers/peci/core.c > > +++ b/drivers/peci/core.c > > @@ -34,7 +34,7 @@ struct device_type peci_controller_type = { > > ??????? .release??????? = peci_controller_dev_release, > > ?}; > > > > -static int peci_controller_scan_devices(struct peci_controller *controller) > > +int peci_controller_scan_devices(struct peci_controller *controller) > > ?{ > > ??????? int ret; > > ??????? u8 addr; > > @@ -159,6 +159,7 @@ EXPORT_SYMBOL_NS_GPL(devm_peci_controller_add, PECI); > > > > ?struct bus_type peci_bus_type = { > > ??????? .name?????????? = "peci", > > +?????? .bus_groups???? = peci_bus_groups, > > ?}; > > > > ?static int __init peci_init(void) > > diff --git a/drivers/peci/device.c b/drivers/peci/device.c > > index 32811248997b..d77d9dabd51e 100644 > > --- a/drivers/peci/device.c > > +++ b/drivers/peci/device.c > > @@ -110,5 +110,6 @@ static void peci_device_release(struct device *dev) > > ?} > > > > ?struct device_type peci_device_type = { > > +?????? .groups???????? = peci_device_groups, > > ??????? .release??????? = peci_device_release, > > ?}; > > diff --git a/drivers/peci/internal.h b/drivers/peci/internal.h > > index 57d11a902c5d..978e12c8e1d3 100644 > > --- a/drivers/peci/internal.h > > +++ b/drivers/peci/internal.h > > @@ -8,6 +8,7 @@ > > ?#include > > > > ?struct peci_controller; > > +struct attribute_group; > > ?struct peci_device; > > ?struct peci_request; > > > > @@ -19,12 +20,16 @@ struct peci_request *peci_request_alloc(struct > > peci_device *device, u8 tx_len, u > > ?void peci_request_free(struct peci_request *req); > > > > ?extern struct device_type peci_device_type; > > +extern const struct attribute_group *peci_device_groups[]; > > > > ?int peci_device_create(struct peci_controller *controller, u8 addr); > > ?void peci_device_destroy(struct peci_device *device); > > > > ?extern struct bus_type peci_bus_type; > > +extern const struct attribute_group *peci_bus_groups[]; > > To me, sysfs.c is small enough to just fold into core.c, then no need > to declare public attribute arrays like this, but up to you if you > prefer the sysfs.c split. Left the sysfs split for now. > > > > > ?extern struct device_type peci_controller_type; > > > > +int peci_controller_scan_devices(struct peci_controller *controller); > > + > > ?#endif /* __PECI_INTERNAL_H */ > > diff --git a/drivers/peci/sysfs.c b/drivers/peci/sysfs.c > > new file mode 100644 > > index 000000000000..db9ef05776e3 > > --- /dev/null > > +++ b/drivers/peci/sysfs.c > > @@ -0,0 +1,82 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > +// Copyright (c) 2021 Intel Corporation > > + > > +#include > > +#include > > +#include > > + > > +#include "internal.h" > > + > > +static int rescan_controller(struct device *dev, void *data) > > +{ > > +?????? if (dev->type != &peci_controller_type) > > +?????????????? return 0; > > + > > +?????? return peci_controller_scan_devices(to_peci_controller(dev)); > > +} > > + > > +static ssize_t rescan_store(struct bus_type *bus, const char *buf, size_t > > count) > > +{ > > +?????? bool res; > > +?????? int ret; > > + > > +?????? ret = kstrtobool(buf, &res); > > +?????? if (ret) > > +?????????????? return ret; > > + > > +?????? if (!res) > > +?????????????? return count; > > + > > +?????? ret = bus_for_each_dev(&peci_bus_type, NULL, NULL, > > rescan_controller); > > +?????? if (ret) > > +?????????????? return ret; > > + > > +?????? return count; > > +} > > +static BUS_ATTR_WO(rescan); > > + > > +static struct attribute *peci_bus_attrs[] = { > > +?????? &bus_attr_rescan.attr, > > +?????? NULL > > +}; > > + > > +static const struct attribute_group peci_bus_group = { > > +?????? .attrs = peci_bus_attrs, > > +}; > > + > > +const struct attribute_group *peci_bus_groups[] = { > > +?????? &peci_bus_group, > > +?????? NULL > > +}; > > + > > +static ssize_t remove_store(struct device *dev, struct device_attribute > > *attr, > > +?????????????????????????? const char *buf, size_t count) > > +{ > > +?????? struct peci_device *device = to_peci_device(dev); > > +?????? bool res; > > +?????? int ret; > > + > > +?????? ret = kstrtobool(buf, &res); > > +?????? if (ret) > > +?????????????? return ret; > > + > > +?????? if (res && device_remove_file_self(dev, attr)) > > +?????????????? peci_device_destroy(device); > > How do you solve races between sysfs device remove and controller > device remove? Looks like double-free at first glance. Have a look at > the? kill_device() helper as one way to resolve this double-delete > race.. Done. Thanks -Iwona > > > + > > +?????? return count; > > +} > > +static DEVICE_ATTR_IGNORE_LOCKDEP(remove, 0200, NULL, remove_store); > > + > > +static struct attribute *peci_device_attrs[] = { > > +?????? &dev_attr_remove.attr, > > +?????? NULL > > +}; > > + > > +static const struct attribute_group peci_device_group = { > > +?????? .attrs = peci_device_attrs, > > +}; > > + > > +const struct attribute_group *peci_device_groups[] = { > > +?????? &peci_device_group, > > +?????? NULL > > +}; > > -- > > 2.31.1 > >