From mboxrd@z Thu Jan 1 00:00:00 1970 From: Samuel Ortiz Subject: Re: [PATCH 07/19] timberdale: mfd_cell is now implicitly available to drivers Date: Mon, 4 Apr 2011 12:03:15 +0200 Message-ID: <20110404100314.GC2751@sortiz-mobl> References: <20110202195417.228e2656@queued.net> <20110202200812.3d8d6cba@queued.net> <20110331230522.GI437@ponder.secretlab.ca> <20110401112030.GA3447@sortiz-mobl> <20110401104756.2f5c6f7a@debxo> <20110401235239.GE29397@sortiz-mobl> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Andres Salomon , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Mark Brown , khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org, ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org, Peter Korsgaard , Mauro Carvalho Chehab , David Brownell , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Mocean Laboratories , Greg Kroah-Hartman To: Grant Likely Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-spi.vger.kernel.org On Fri, Apr 01, 2011 at 05:58:44PM -0600, Grant Likely wrote: > On Fri, Apr 1, 2011 at 5:52 PM, Samuel Ortiz = wrote: > > On Fri, Apr 01, 2011 at 11:56:35AM -0600, Grant Likely wrote: > >> On Fri, Apr 1, 2011 at 11:47 AM, Andres Salomon wrote: > >> > On Fri, 1 Apr 2011 13:20:31 +0200 > >> > Samuel Ortiz wrote: > >> > > >> >> Hi Grant, > >> >> > >> >> On Thu, Mar 31, 2011 at 05:05:22PM -0600, Grant Likely wrote: > >> > [...] > >> >> > Gah. =A0Not all devices instantiated via mfd will be an mfd d= evice, > >> >> > which means that the driver may very well expect an *entirely > >> >> > different* platform_device pointer; which further means a ver= y high > >> >> > potential of incorrectly dereferenced structures (as evidence= d by a > >> >> > patch series that is not bisectable). =A0For instance, the xi= linx ip > >> >> > cores are used by more than just mfd. > >> >> I agree. Since the vast majority of the MFD subdevices are MFD > >> >> specific IPs, I overlooked that part. The impacted drivers are = the > >> >> timberdale and the DaVinci voice codec ones. > >> > >> Another option is you could do this for MFD devices: > >> > >> struct mfd_device { > >> =A0 =A0 =A0 =A0 struct platform_devce pdev; > >> =A0 =A0 =A0 =A0 struct mfd_cell *cell; > >> }; > >> > >> However, that requires that drivers using the mfd_cell will *never= * > >> get instantiated outside of the mfd infrastructure, and there is n= o > >> way to protect against this so it is probably a bad idea. > >> > >> Or, mfd_cell could be added to platform_device directly which woul= d > >> *by far* be the safest option at the cost of every platform_device > >> having a mostly unused mfd_cell pointer. =A0Not a significant cost= in my > >> opinion. > > I thought about this one, but I had the impression people would wan= t to kill > > me for adding an MFD specific pointer to platform_device. I guess i= t's worth > > giving it a try since it would be a simple and safe solution. > > I'll look at it later this weekend. > > > > Thanks for the input. >=20 > [cc'ing gregkh because we're talking about modifying struct platform_= device] >=20 > I'll back you up on this one. It is a far better solution than the > alternatives. At least with mfd, it covers a large set of devices. = I > think there is a strong argument for doing this. Or alternatively, > the particular interesting fields from mfd_cell could be added to > platform_device. What information do child devices need access to? In some cases, they need the whole cell to clone it. So I'm up for addi= ng an mfd_cell pointer to the platform_device structure. Below is a tentative patch. This is a first step and would fix all regressions. I tried to keep the MFD dependencies as small as possible,= which is why I placed the pdev->mfd_cell building code in mfd-core.c The second step would be to get rid of mfd_get_data() and have all subd= rivers going back to the regular platform_data way. They would no longer be de= pendant on the MFD code except for those who really need it. In that case they = could just call mfd_get_cell() and get full access to their MFD cell. ---=20 drivers/mfd/mfd-core.c | 27 ++++++++++++++++++++++----- include/linux/mfd/core.h | 7 +++++-- include/linux/platform_device.h | 5 +++++ 3 files changed, 32 insertions(+), 7 deletions(-) diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c index d01574d..c0fc1c0 100644 --- a/drivers/mfd/mfd-core.c +++ b/drivers/mfd/mfd-core.c @@ -18,6 +18,21 @@ #include #include =20 +static int mfd_platform_add_cell(struct platform_device *pdev, const s= truct mfd_cell *cell) +{ + struct mfd_cell *c; + + if (cell =3D=3D NULL) + return 0; + + c =3D kmemdup(cell, sizeof(struct mfd_cell), GFP_KERNEL); + if (c =3D=3D NULL) + return -ENOMEM; + + pdev->mfd_cell =3D c; + return 0; +} + int mfd_cell_enable(struct platform_device *pdev) { const struct mfd_cell *cell =3D mfd_get_cell(pdev); @@ -75,7 +90,7 @@ static int mfd_add_device(struct device *parent, int = id, =20 pdev->dev.parent =3D parent; =20 - ret =3D platform_device_add_data(pdev, cell, sizeof(*cell)); + ret =3D mfd_platform_add_cell(pdev, cell); if (ret) goto fail_res; =20 @@ -104,17 +119,17 @@ static int mfd_add_device(struct device *parent, = int id, if (!cell->ignore_resource_conflicts) { ret =3D acpi_check_resource_conflict(res); if (ret) - goto fail_res; + goto fail_cell; } } =20 ret =3D platform_device_add_resources(pdev, res, cell->num_resources)= ; if (ret) - goto fail_res; + goto fail_cell; =20 ret =3D platform_device_add(pdev); if (ret) - goto fail_res; + goto fail_cell; =20 if (cell->pm_runtime_no_callbacks) pm_runtime_no_callbacks(&pdev->dev); @@ -123,7 +138,8 @@ static int mfd_add_device(struct device *parent, in= t id, =20 return 0; =20 -/* platform_device_del(pdev); */ +fail_cell: + kfree(pdev->mfd_cell); fail_res: kfree(res); fail_device: @@ -171,6 +187,7 @@ static int mfd_remove_devices_fn(struct device *dev= , void *c) if (!*usage_count || (cell->usage_count < *usage_count)) *usage_count =3D cell->usage_count; =20 + kfree(pdev->mfd_cell); platform_device_unregister(pdev); return 0; } diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h index ad1b19a..0e4d3a6 100644 --- a/include/linux/mfd/core.h +++ b/include/linux/mfd/core.h @@ -86,7 +86,7 @@ extern int mfd_clone_cell(const char *cell, const cha= r **clones, */ static inline const struct mfd_cell *mfd_get_cell(struct platform_devi= ce *pdev) { - return pdev->dev.platform_data; + return pdev->mfd_cell; } =20 /* @@ -95,7 +95,10 @@ static inline const struct mfd_cell *mfd_get_cell(st= ruct platform_device *pdev) */ static inline void *mfd_get_data(struct platform_device *pdev) { - return mfd_get_cell(pdev)->mfd_data; + if (pdev->mfd_cell !=3D NULL) + return mfd_get_cell(pdev)->mfd_data; + else + return pdev->dev.platform_data; } =20 extern int mfd_add_devices(struct device *parent, int id, diff --git a/include/linux/platform_device.h b/include/linux/platform_d= evice.h index d96db98..734d254 100644 --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -14,6 +14,8 @@ #include #include =20 +struct mfd_cell; + struct platform_device { const char * name; int id; @@ -23,6 +25,9 @@ struct platform_device { =20 const struct platform_device_id *id_entry; =20 + /* MFD cell pointer */ + struct mfd_cell *mfd_cell; + /* arch specific additions */ struct pdev_archdata archdata; }; --=20 Intel Open Source Technology Centre http://oss.intel.com/