From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@roeck-us.net (Guenter Roeck) Date: Fri, 9 Sep 2016 14:56:53 -0700 Subject: [PATCH v2] hwmon: xgene: access mailbox as RAM In-Reply-To: <3475893.910N1IvcYZ@wuerfel> References: <1469134557-26869-1-git-send-email-hotran@apm.com> <2852054.37zytD0HIa@wuerfel> <3475893.910N1IvcYZ@wuerfel> Message-ID: <20160909215653.GA2362@roeck-us.net> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Sep 09, 2016 at 10:10:45PM +0200, Arnd Bergmann wrote: > The newly added hwmon driver fails to build in an allmodconfig > kernel: > > ERROR: "memblock_is_memory" [drivers/hwmon/xgene-hwmon.ko] undefined! > > According to comments in the code, the mailbox is a shared memory region, > not a set of MMIO registers, so we should use memremap() for mapping it > instead of ioremap or acpi_os_ioremap, and pointer dereferences instead > of readl/writel. > > The driver already uses plain kernel pointers, so it's a bit unusual > to work with functions that operate on __iomem pointers, and this > fixes that part too. > > I'm using READ_ONCE/WRITE_ONCE here to keep the existing behavior > regarding the ordering of the accesses from the CPU, but note that > there are no barriers (also unchanged from before). > > I'm also keeping the endianess behavior, though I'm unsure whether > the message data was supposed to be in LE32 format in the first > place, it's possible this was meant to be interpreted as a byte > stream instead. > > Signed-off-by: Arnd Bergmann Applied after 's/endianess/endianness/' to make checkpatch happy. Thanks, Guenter