From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rongrong Zou Subject: Re: [PATCH v1 3/3] ARM64 LPC: update binding doc Date: Wed, 6 Jan 2016 21:36:33 +0800 Message-ID: <568D1861.1070201@huawei.com> References: <1451396032-23708-1-git-send-email-zourongrong@gmail.com> <6384244.Uhpjfgly6O@wuerfel> <568BB035.1050801@huawei.com> <2550495.K9prJVsVEi@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <2550495.K9prJVsVEi@wuerfel> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Arnd Bergmann Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Rongrong Zou , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Catalin Marinas , Corey Minyard , gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, Will Deacon , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linuxarm-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org, liviu.dudau-5wv7dgnIgG8@public.gmane.org List-Id: devicetree@vger.kernel.org =E5=9C=A8 2016/1/5 20:19, Arnd Bergmann =E5=86=99=E9=81=93: > On Tuesday 05 January 2016 19:59:49 Rongrong Zou wrote: >> =E5=9C=A8 2016/1/5 0:34, Arnd Bergmann =E5=86=99=E9=81=93: >>> On Tuesday 05 January 2016 00:04:19 Rongrong Zou wrote: >>>> =E5=9C=A8 2016/1/4 19:13, Arnd Bergmann =E5=86=99=E9=81=93: >>>>> On Sunday 03 January 2016 20:24:14 Rongrong Zou wrote: >>>>>> =E5=9C=A8 2015/12/31 23:00, Rongrong Zou =E5=86=99=E9=81=93: >>>> Ranges property can set empty, but this means 1:1 translation. the= I/O >>>> port range is translated to MMIO address 0x00000001 00000000 to >>>> 0x00000001 00000004, it looks wrong else. I wonder if anyone get l= egacy >>>> I/O port resource from dts. >>> >>> As I said, nothing should really require the ranges property here, = unless >>> you have a valid IORESOURCE_MEM translation. The code that requires >>> the ranges to be present is wrong. >>> >> >> I think the openfirmware(DT) do not support for those unmapped I/O p= orts, because I >> must get resource by calling of_address_to_resource(), which have to= call >> pci_address_to_pio() when resource type is IORESOURCE_IO. I'm sorry = I have no >> better idea for this now. Maybe liviu can give me some opinions. > > I think on x86 it works (or used to work, few people use open firmwar= e on > x86 these days, and it may be broken), and the pci_address_to_pio() c= all > behaves differently when PCI_IOBASE is set. x86 never maps I/O ports = into > memory mapped I/O addresses, they have their own way of accessing the= m > just like your platform. > >> /** >> * of_address_to_resource - Translate device tree address and retu= rn as resource >> * >> * Note that if your address is a PIO address, the conversion will= fail if >> * the physical address can't be internally converted to an IO tok= en with >> * pci_address_to_pio(), that is because it's either called to ear= ly or it >> * can't be matched to any host bridge IO space >> */ >> int of_address_to_resource(struct device_node *dev, int index, >> struct resource *r) > > The problem here seems to be that the code assumes that either the I/= O ports > are always mapped or they are never mapped (no PCI_IOBASE). We need t= o extend > it because now we can have the combination of the two. I am considering the following solution: Adding unmapped isa io functions in drivers/of/address.c, static LIST_HEAD(legacy_io_range_list); int isa_register_io_range(phys_addr_t addr, resource_size_t size); /* before I call isa(LPC) bus driver, the input I/O port must be transl= ated to phys_addr_t (the least 16bit means port addr on bus, the second 16bit means bus id)= */ phys_addr_t isa_pio_to_bus_addr(unsigned long pio); /* the returned PIO do not conflict with PIO get from pci_address_to_pi= o*/ unsigned long isa_bus_addr_to_pio(phys_addr_t address); drivers/bus/lpc.c lpc_bus_probe() { isa_register_io_range(phys_addr_t addr, resource_size_t size); } inb(unsigned long port) { unsigned short bus; phys_addr_t addr; /*hit isa port range*/ if(addr =3D isa_pio_to_bus_addr(port)) { bus =3D (addr >> 16) & 0xffff; call lpc driver with addr; return lpc_read_byte(bus, addr); } else /*not hit*/ { return readb(PCI_IOBASE + port); } } > >>>> For ipmi driver, I can get I/O port resource by DMI rather than dt= s. >>> >>> No, the ipmi driver uses the resource that belongs to the platform >>> device already, you can't rely on DMI data to be present there. >> >> Ipmi has a lot of way to be discovered(ACPI, DMI, hardcoded, hot-add= , >> openfirmware and a few other), I think we just use one of them, not = all of them. >> It depend on vendor's hardware solution actually. > > I don't think we should mix multiple methods here: if the bus is desc= ribed > in DT, all its children should be there as well. Otherwise you get in= to problems > e.g. if you have multiple instances of the LPC bus and the Linux I/O = addresses > for one or more of them have an offset to the bus specific addresses. > > The bus probe code decides what the Linux I/O port numbers are, but D= MI > and other methods have no idea of the mapping. As long as there is on= ly > one instance, using the first 0x1000 addresses with a 1:1 mapping sav= es > us a bit of trouble, but I'd be worried about relying on that assumpt= ion > too much. > > Arnd > > > . > Thanks, Rongrong -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html