openbmc.lists.ozlabs.org archive mirror
 help / color / mirror / Atom feed
From: "Winiarska, Iwona" <iwona.winiarska@intel.com>
To: "Williams, Dan J" <dan.j.williams@intel.com>
Cc: "linux-aspeed@lists.ozlabs.org" <linux-aspeed@lists.ozlabs.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"zweiss@equinix.com" <zweiss@equinix.com>,
	"jae.hyun.yoo@linux.intel.com" <jae.hyun.yoo@linux.intel.com>,
	"andriy.shevchenko@linux.intel.com"
	<andriy.shevchenko@linux.intel.com>,
	"corbet@lwn.net" <corbet@lwn.net>,
	"openbmc@lists.ozlabs.org" <openbmc@lists.ozlabs.org>,
	"x86@kernel.org" <x86@kernel.org>,
	"pierre-louis.bossart@linux.intel.com"
	<pierre-louis.bossart@linux.intel.com>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"linux@roeck-us.net" <linux@roeck-us.net>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"jdelvare@suse.com" <jdelvare@suse.com>,
	"arnd@arndb.de" <arnd@arndb.de>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	"bp@alien8.de" <bp@alien8.de>,
	"Lutomirski, Andy" <luto@kernel.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"mchehab@kernel.org" <mchehab@kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-hwmon@vger.kernel.org" <linux-hwmon@vger.kernel.org>,
	"Luck, Tony" <tony.luck@intel.com>,
	"andrew@aj.id.au" <andrew@aj.id.au>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"rdunlap@infradead.org" <rdunlap@infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"yazen.ghannam@amd.com" <yazen.ghannam@amd.com>,
	"olof@lixom.net" <olof@lixom.net>
Subject: Re: [PATCH v2 08/15] peci: Add device detection
Date: Mon, 15 Nov 2021 22:18:06 +0000	[thread overview]
Message-ID: <b664e784f2b14ac75693af0982fdcb1af89ef583.camel@intel.com> (raw)
In-Reply-To: <CAPcyv4hPLReB6wGTDBM_tnqRUXxNASFCtgCw0=aDW+PPfSJ57A@mail.gmail.com>

On Fri, 2021-08-27 at 12:01 -0700, Dan Williams wrote:
> On Tue, Aug 3, 2021 at 4:35 AM Iwona Winiarska
> <iwona.winiarska@intel.com> wrote:
> > 
> > Since PECI devices are discoverable, we can dynamically detect devices
> > that are actually available in the system.
> > 
> > This change complements the earlier implementation by rescanning PECI
> > bus to detect available devices. For this purpose, it also introduces the
> > minimal API for PECI requests.
> > 
> > Signed-off-by: Iwona Winiarska <iwona.winiarska@intel.com>
> > Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
> > ---
> >  drivers/peci/Makefile   |   2 +-
> >  drivers/peci/core.c     |  33 ++++++++++++
> >  drivers/peci/device.c   | 114 ++++++++++++++++++++++++++++++++++++++++
> >  drivers/peci/internal.h |  14 +++++
> >  drivers/peci/request.c  |  50 ++++++++++++++++++
> >  5 files changed, 212 insertions(+), 1 deletion(-)
> >  create mode 100644 drivers/peci/device.c
> >  create mode 100644 drivers/peci/request.c
> > 
> > diff --git a/drivers/peci/Makefile b/drivers/peci/Makefile
> > index 926d8df15cbd..c5f9d3fe21bb 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
> > +peci-y := core.o request.o device.o
> >  obj-$(CONFIG_PECI) += peci.o
> > 
> >  # Hardware specific bus drivers
> > diff --git a/drivers/peci/core.c b/drivers/peci/core.c
> > index 7b3938af0396..d143f1a7fe98 100644
> > --- a/drivers/peci/core.c
> > +++ b/drivers/peci/core.c
> > @@ -34,6 +34,20 @@ struct device_type peci_controller_type = {
> >         .release        = peci_controller_dev_release,
> >  };
> > 
> > +static int peci_controller_scan_devices(struct peci_controller *controller)
> > +{
> > +       int ret;
> > +       u8 addr;
> > +
> > +       for (addr = PECI_BASE_ADDR; addr < PECI_BASE_ADDR +
> > PECI_DEVICE_NUM_MAX; addr++) {
> > +               ret = peci_device_create(controller, addr);
> > +               if (ret)
> > +                       return ret;
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> >  static struct peci_controller *peci_controller_alloc(struct device *dev,
> >                                                      struct
> > peci_controller_ops *ops)
> >  {
> > @@ -76,10 +90,23 @@ static struct peci_controller
> > *peci_controller_alloc(struct device *dev,
> >         return ERR_PTR(ret);
> >  }
> > 
> > +static int unregister_child(struct device *dev, void *dummy)
> > +{
> > +       peci_device_destroy(to_peci_device(dev));
> > +
> > +       return 0;
> > +}
> > +
> >  static void unregister_controller(void *_controller)
> >  {
> >         struct peci_controller *controller = _controller;
> > 
> > +       /*
> > +        * Detach any active PECI devices. This can't fail, thus we do not
> > +        * check the returned value.
> > +        */
> > +       device_for_each_child_reverse(&controller->dev, NULL,
> > unregister_child);
> > +
> >         device_unregister(&controller->dev);
> >  }
> > 
> > @@ -115,6 +142,12 @@ struct peci_controller *devm_peci_controller_add(struct
> > device *dev,
> >         if (ret)
> >                 return ERR_PTR(ret);
> > 
> > +       /*
> > +        * Ignoring retval since failures during scan are non-critical for
> > +        * controller itself.
> > +        */
> > +       peci_controller_scan_devices(controller);
> > +
> >         return controller;
> > 
> >  err:
> > diff --git a/drivers/peci/device.c b/drivers/peci/device.c
> > new file mode 100644
> > index 000000000000..32811248997b
> > --- /dev/null
> > +++ b/drivers/peci/device.c
> > @@ -0,0 +1,114 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +// Copyright (c) 2018-2021 Intel Corporation
> > +
> > +#include <linux/peci.h>
> > +#include <linux/slab.h>
> > +
> > +#include "internal.h"
> > +
> > +static int peci_detect(struct peci_controller *controller, u8 addr)
> > +{
> > +       struct peci_request *req;
> > +       int ret;
> > +
> > +       /*
> > +        * PECI Ping is a command encoded by tx_len = 0, rx_len = 0.
> > +        * We expect correct Write FCS if the device at the target address
> > +        * is able to respond.
> > +        */
> > +       req = peci_request_alloc(NULL, 0, 0);
> > +       if (!req)
> > +               return -ENOMEM;
> 
> Seems a waste to do a heap allocation for this routine. Why not:
> 
>        /*
>         * PECI Ping is a command encoded by tx_len = 0, rx_len = 0.
>         * We expect correct Write FCS if the device at the target address
>         * is able to respond.
>         */
>        struct peci_request req = { 0 };

Done.

> 
> > +
> > +       mutex_lock(&controller->bus_lock);
> > +       ret = controller->ops->xfer(controller, addr, req);
> > +       mutex_unlock(&controller->bus_lock);
> > +
> > +       peci_request_free(req);
> > +
> > +       return ret;
> > +}
> > +
> > +static bool peci_addr_valid(u8 addr)
> > +{
> > +       return addr >= PECI_BASE_ADDR && addr < PECI_BASE_ADDR +
> > PECI_DEVICE_NUM_MAX;
> > +}
> > +
> > +static int peci_dev_exists(struct device *dev, void *data)
> > +{
> > +       struct peci_device *device = to_peci_device(dev);
> > +       u8 *addr = data;
> > +
> > +       if (device->addr == *addr)
> > +               return -EBUSY;
> > +
> > +       return 0;
> > +}
> > +
> > +int peci_device_create(struct peci_controller *controller, u8 addr)
> > +{
> > +       struct peci_device *device;
> > +       int ret;
> > +
> > +       if (WARN_ON(!peci_addr_valid(addr)))
> 
> The WARN_ON is overkill, especially as there is only one caller of
> this and it loops through valid addresses.

Done.

> 
> > +               return -EINVAL;
> > +
> > +       /* Check if we have already detected this device before. */
> > +       ret = device_for_each_child(&controller->dev, &addr,
> > peci_dev_exists);
> > +       if (ret)
> > +               return 0;
> > +
> > +       ret = peci_detect(controller, addr);
> > +       if (ret) {
> > +               /*
> > +                * Device not present or host state doesn't allow successful
> > +                * detection at this time.
> > +                */
> > +               if (ret == -EIO || ret == -ETIMEDOUT)
> > +                       return 0;
> > +
> > +               return ret;
> > +       }
> > +
> > +       device = kzalloc(sizeof(*device), GFP_KERNEL);
> > +       if (!device)
> > +               return -ENOMEM;
> > +
> > +       device->addr = addr;
> > +       device->dev.parent = &controller->dev;
> > +       device->dev.bus = &peci_bus_type;
> > +       device->dev.type = &peci_device_type;
> > +
> > +       ret = dev_set_name(&device->dev, "%d-%02x", controller->id, device-
> > >addr);
> > +       if (ret)
> > +               goto err_free;
> 
> It's cleaner to just have one unified error exit using put_device().
> Use the device_initialize() + device_add() pattern, not
> device_register().

Done.

> 
> 
> > +
> > +       ret = device_register(&device->dev);
> > +       if (ret)
> > +               goto err_put;
> > +
> > +       return 0;
> > +
> > +err_put:
> > +       put_device(&device->dev);
> > +err_free:
> > +       kfree(device);
> > +
> > +       return ret;
> > +}
> > +
> > +void peci_device_destroy(struct peci_device *device)
> > +{
> > +       device_unregister(&device->dev);
> 
> No clear value for this wrapper, in fact in one caller it causes it to
> do a to_peci_device() just this helper can undo that up-cast.

It gains value after extending it with kill_device().

> 
> > +}
> > +
> > +static void peci_device_release(struct device *dev)
> > +{
> > +       struct peci_device *device = to_peci_device(dev);
> > +
> > +       kfree(device);
> > +}
> > +
> > +struct device_type peci_device_type = {
> > +       .release        = peci_device_release,
> > +};
> > diff --git a/drivers/peci/internal.h b/drivers/peci/internal.h
> > index 918dea745a86..57d11a902c5d 100644
> > --- a/drivers/peci/internal.h
> > +++ b/drivers/peci/internal.h
> > @@ -8,6 +8,20 @@
> >  #include <linux/types.h>
> > 
> >  struct peci_controller;
> > +struct peci_device;
> > +struct peci_request;
> > +
> > +/* PECI CPU address range 0x30-0x37 */
> > +#define PECI_BASE_ADDR         0x30
> > +#define PECI_DEVICE_NUM_MAX    8
> > +
> > +struct peci_request *peci_request_alloc(struct peci_device *device, u8
> > tx_len, u8 rx_len);
> > +void peci_request_free(struct peci_request *req);
> > +
> > +extern struct device_type peci_device_type;
> > +
> > +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;
> > 
> > diff --git a/drivers/peci/request.c b/drivers/peci/request.c
> > new file mode 100644
> > index 000000000000..81b567bc7b87
> > --- /dev/null
> > +++ b/drivers/peci/request.c
> > @@ -0,0 +1,50 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +// Copyright (c) 2021 Intel Corporation
> > +
> > +#include <linux/export.h>
> > +#include <linux/peci.h>
> > +#include <linux/slab.h>
> > +#include <linux/types.h>
> > +
> > +#include "internal.h"
> > +
> > +/**
> > + * peci_request_alloc() - allocate &struct peci_requests
> > + * @device: PECI device to which request is going to be sent
> > + * @tx_len: TX length
> > + * @rx_len: RX length
> > + *
> > + * Return: A pointer to a newly allocated &struct peci_request on success
> > or NULL otherwise.
> > + */
> > +struct peci_request *peci_request_alloc(struct peci_device *device, u8
> > tx_len, u8 rx_len)
> > +{
> > +       struct peci_request *req;
> > +
> > +       if (WARN_ON_ONCE(tx_len > PECI_REQUEST_MAX_BUF_SIZE || rx_len >
> > PECI_REQUEST_MAX_BUF_SIZE))
> 
> WARN_ON_ONCE() should only be here to help other kernel developers not
> make this mistake However, another way to enforce this is to stop
> exporting peci_request_alloc() and instead export helpers for specific
> command types, and keep this detail internal to the core. If you keep
> this, it needs a comment that it is only here to warn other
> peci-client developers of their bug before it goes upstream.

Added comment.

Thanks
-Iwona


  reply	other threads:[~2021-11-16  1:58 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-03 11:31 [PATCH v2 00/15] Introduce PECI subsystem Iwona Winiarska
2021-08-03 11:31 ` [PATCH v2 01/15] x86/cpu: Move intel-family to arch-independent headers Iwona Winiarska
2021-10-04 19:03   ` Borislav Petkov
2021-10-11 19:21     ` Winiarska, Iwona
2021-10-11 19:40       ` Dave Hansen
2021-10-11 20:53         ` Winiarska, Iwona
2021-10-11 23:12           ` Dave Hansen
2021-10-11 20:06       ` Borislav Petkov
2021-10-11 20:38         ` Winiarska, Iwona
2021-10-11 21:31           ` Borislav Petkov
2021-10-12 23:15             ` Winiarska, Iwona
2021-10-13  6:42               ` Borislav Petkov
2021-08-03 11:31 ` [PATCH v2 02/15] x86/cpu: Extract cpuid helpers to arch-independent Iwona Winiarska
2021-10-04 19:08   ` Borislav Petkov
2021-10-11 19:32     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 03/15] dt-bindings: Add generic bindings for PECI Iwona Winiarska
2021-08-11 18:11   ` Rob Herring
2021-08-03 11:31 ` [PATCH v2 04/15] dt-bindings: Add bindings for peci-aspeed Iwona Winiarska
2021-08-11 18:11   ` Rob Herring
2021-08-03 11:31 ` [PATCH v2 05/15] ARM: dts: aspeed: Add PECI controller nodes Iwona Winiarska
2021-08-03 11:31 ` [PATCH v2 06/15] peci: Add core infrastructure Iwona Winiarska
2021-08-25 22:58   ` Dan Williams
2021-08-26 22:40     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 07/15] peci: Add peci-aspeed controller driver Iwona Winiarska
2021-08-26  1:35   ` Dan Williams
2021-08-26 23:54     ` Winiarska, Iwona
2021-08-27 16:24       ` Dan Williams
2021-08-29 19:42         ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 08/15] peci: Add device detection Iwona Winiarska
2021-08-27 19:01   ` Dan Williams
2021-11-15 22:18     ` Winiarska, Iwona [this message]
2021-08-03 11:31 ` [PATCH v2 09/15] peci: Add sysfs interface for PECI bus Iwona Winiarska
2021-08-27 19:11   ` Dan Williams
2021-11-15 22:19     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 10/15] peci: Add support for PECI device drivers Iwona Winiarska
2021-08-27 21:19   ` Dan Williams
2021-11-15 22:20     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 11/15] peci: Add peci-cpu driver Iwona Winiarska
2021-08-03 11:31 ` [PATCH v2 12/15] hwmon: peci: Add cputemp driver Iwona Winiarska
2021-08-03 15:24   ` Guenter Roeck
2021-08-04 10:43     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 13/15] hwmon: peci: Add dimmtemp driver Iwona Winiarska
2021-08-03 15:39   ` Guenter Roeck
2021-08-04 10:46     ` Winiarska, Iwona
2021-08-04 17:33       ` Guenter Roeck
2021-08-05 21:48         ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 14/15] docs: hwmon: Document PECI drivers Iwona Winiarska
2021-08-03 11:31 ` [PATCH v2 15/15] docs: Add PECI documentation Iwona Winiarska
2021-08-05 12:17 ` [PATCH v2 00/15] Introduce PECI subsystem Greg Kroah-Hartman

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=b664e784f2b14ac75693af0982fdcb1af89ef583.camel@intel.com \
    --to=iwona.winiarska@intel.com \
    --cc=andrew@aj.id.au \
    --cc=andriy.shevchenko@linux.intel.com \
    --cc=arnd@arndb.de \
    --cc=bp@alien8.de \
    --cc=corbet@lwn.net \
    --cc=dan.j.williams@intel.com \
    --cc=devicetree@vger.kernel.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=jae.hyun.yoo@linux.intel.com \
    --cc=jdelvare@suse.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-aspeed@lists.ozlabs.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-hwmon@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@roeck-us.net \
    --cc=luto@kernel.org \
    --cc=mchehab@kernel.org \
    --cc=mingo@redhat.com \
    --cc=olof@lixom.net \
    --cc=openbmc@lists.ozlabs.org \
    --cc=pierre-louis.bossart@linux.intel.com \
    --cc=rdunlap@infradead.org \
    --cc=robh+dt@kernel.org \
    --cc=tglx@linutronix.de \
    --cc=tony.luck@intel.com \
    --cc=x86@kernel.org \
    --cc=yazen.ghannam@amd.com \
    --cc=zweiss@equinix.com \
    --subject='Re: [PATCH v2 08/15] peci: Add device detection' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).