From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752684AbcAGDiO (ORCPT ); Wed, 6 Jan 2016 22:38:14 -0500 Received: from szxga01-in.huawei.com ([58.251.152.64]:3916 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751450AbcAGDiL (ORCPT ); Wed, 6 Jan 2016 22:38:11 -0500 Subject: Re: [PATCH v1 3/3] ARM64 LPC: update binding doc To: Arnd Bergmann References: <1451396032-23708-1-git-send-email-zourongrong@gmail.com> <6384244.Uhpjfgly6O@wuerfel> <568BB035.1050801@huawei.com> <2550495.K9prJVsVEi@wuerfel> <568D1861.1070201@huawei.com> CC: , , Corey Minyard , , Will Deacon , , , Catalin Marinas , Rongrong Zou , , From: Rongrong Zou Message-ID: <568DDD7F.5040909@huawei.com> Date: Thu, 7 Jan 2016 11:37:35 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <568D1861.1070201@huawei.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.177.30.66] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A0B0206.568DDD8F.0068,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: ac15b06e153a41e4c30614159d31b5bd Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2016/1/6 21:36, Rongrong Zou 写道: > 在 2016/1/5 20:19, Arnd Bergmann 写道: >> On Tuesday 05 January 2016 19:59:49 Rongrong Zou wrote: >>> 在 2016/1/5 0:34, Arnd Bergmann 写道: >>>> On Tuesday 05 January 2016 00:04:19 Rongrong Zou wrote: >>>>> 在 2016/1/4 19:13, Arnd Bergmann 写道: >>>>>> On Sunday 03 January 2016 20:24:14 Rongrong Zou wrote: >>>>>>> 在 2015/12/31 23:00, Rongrong Zou 写道: >>>>> 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 legacy >>>>> 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 ports, 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 firmware on >> x86 these days, and it may be broken), and the pci_address_to_pio() call >> 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 them >> just like your platform. >> The big problem is: The return value of_translate_address can be only an cpu addr, there is no map from cpuaddr to I/O port in x86 as you said, we still can't get io resource. static int __of_address_to_resource(struct device_node *dev, const __be32 *addrp, u64 size, unsigned int flags, const char *name, struct resource *r) { ... taddr = of_translate_address(dev, addrp); ... } >>> /** >>> * of_address_to_resource - Translate device tree address and return 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 token with >>> * pci_address_to_pio(), that is because it's either called to early 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 to 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 translated 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_pio*/ > 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 = isa_pio_to_bus_addr(port)) > { > bus = (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 dts. >>>> >>>> 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 described >> in DT, all its children should be there as well. Otherwise you get into 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 DMI >> and other methods have no idea of the mapping. As long as there is only >> one instance, using the first 0x1000 addresses with a 1:1 mapping saves >> us a bit of trouble, but I'd be worried about relying on that assumption >> too much. >> >> Arnd >> >> >> . -- Thanks, Rongrong