From mboxrd@z Thu Jan 1 00:00:00 1970 From: ddaney@caviumnetworks.com (David Daney) Date: Tue, 22 Dec 2015 10:29:31 -0800 Subject: [PATCH 1/2] PCI: generic: Refactor code to enable reuse by other drivers. In-Reply-To: <20151222100732.GD32623@arm.com> References: <1450749222-15966-1-git-send-email-ddaney.cavm@gmail.com> <1450749222-15966-2-git-send-email-ddaney.cavm@gmail.com> <20151222100732.GD32623@arm.com> Message-ID: <5679968B.4090908@caviumnetworks.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 12/22/2015 02:07 AM, Will Deacon wrote: > On Mon, Dec 21, 2015 at 05:53:41PM -0800, David Daney wrote: >> From: David Daney >> >> No change in functionality. >> >> Move structure definitions into a separate header file. Split probe >> function in to two parts: >> >> - a small driver specific probe function (gen_pci_probe) >> >> - a common probe that can be used by other drivers >> (gen_pci_common_probe) >> >> Signed-off-by: David Daney >> --- >> drivers/pci/host/pci-host-generic.c | 53 ++++++++++++----------------------- >> drivers/pci/host/pci-host-generic.h | 56 +++++++++++++++++++++++++++++++++++++ >> 2 files changed, 74 insertions(+), 35 deletions(-) >> create mode 100644 drivers/pci/host/pci-host-generic.h >> >> diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c >> index 5434c90..e83cec7 100644 >> --- a/drivers/pci/host/pci-host-generic.c >> +++ b/drivers/pci/host/pci-host-generic.c [...] >> -static int gen_pci_probe(struct platform_device *pdev) >> +int gen_pci_common_probe(struct platform_device *pdev, >> + struct gen_pci *pci) > > Whilst I'm fine with this patch, I don't know how Bjorn will feel about > exposing this function outside of the generic host driver. We could avoid > it by turning things upside-down and having the generic driver probe > the other drivers by matching a compatible string with a probe function > pointer, but I'd be interested to see what others think. > Note: I know that pci-host-generic is not built as a loadable module, but... struct of_device_id, MODULE_DEVICE_TABLE, struct platform_driver and the registering of platform drivers is fairly well standardized in the kernel, and module loading userpace tools. The struct of_device_id, MODULE_DEVICE_TABLE must really reside in the same module as the driver for the device. We are creating a separate driver precisely because we don't want to mix all this ThunderX specific code into the pci-host-generic driver when it is used by arm-32bit and others. This means that, at a minimum, we would have to export the pci-host-generic probe function so that it could be referenced by struct platform_driver in other modules. This brings up the next problem. How to attach driver specific data to the generic driver structures? At first I tried augmenting struct gen_pci_cfg_bus_ops with a callback .init() function to be called by the generic driver, but this would also require adding an an element to struct gen_pci to point to a driver specific data object. It felt a little convoluted and complex. This led me to the current design where struct gen_pci is embedded in the driver specific structure, and the allocation of this is done in the driver specific probe function. No more callbacks, no additions to the pci-host-generic structures. I think it is a little cleaner this way. If there are suggestions as to how it can be made cleaner yet, I would be happy to implement and test them. David Daney > Will >