Hi Pratyush, On Thursday 26 June 2014 12:03 PM, Pratyush Anand wrote: > Hi Kishon, > > On Thu, Jun 26, 2014 at 02:10:02PM +0800, Kishon Vijay Abraham I wrote: >> Hi Pratyush, >> >> On Thursday 26 June 2014 11:07 AM, Pratyush Anand wrote: >>> Hi Kishon, >>> >>> Few things, if you can help me to understand: >>> >>> On Wed, Jun 25, 2014 at 11:26 PM, Kishon Vijay Abraham I <kishon@xxxxxx> wrote: >>>> In DRA7, the cpu sees 32bit address, but the pcie controller can see only 28bit >>>> address. So whenever the cpu issues a read/write request, the 4 most >>>> significant bits are used by L3 to determine the target controller. >>>> For example, the cpu reserves 0x2000_0000 - 0x2FFF_FFFF for PCIe controller but >>>> the PCIe controller will see only (0x000_0000 - 0xFFF_FFF). So for programming >>>> the outbound translation window the *base* should be programmed as 0x000_0000. >>>> Whenever we try to write to say 0x2000_0000, it will be translated to whatever >>>> we have programmed in the translation window with base as 0x000_0000. >>>> >>>> This is needed when the dt node is modelled something like below >>>> axi { >>>> compatible = "simple-bus"; >>>> #size-cells = <1>; >>>> #address-cells = <1>; >>>> ranges = <0x0 0x20000000 0x10000000 // 28-bit bus >>>> 0x51000000 0x51000000 0x3000>; >>>> pcie@51000000 { >>>> reg = <0x1000 0x2000>, <0x51002000 0x14c>, <0x51000000 0x2000>; >>>> reg-names = "config", "ti_conf", "rc_dbics"; >>> >>> So for DRA7, config base which will be coming from reg property should >>> be 0x1000 and size 0x2000, no? >> >> right. The first element in 'reg' and 'reg-names' specify exactly that. >>> >>>> #address-cells = <3>; >>>> #size-cells = <2>; >>>> ranges = <0x81000000 0 0 0x03000 0 0x00010000 >>> >>> range type 0x81000000 tells that it is IO >>> >>>> 0x82000000 0 0x20013000 0x13000 0 0xffed000>; >>> >>> range type 0x81000000 tells that it is mem >>> >>> >>>> }; >>>> }; >>>> >>>> Here the CPU address for configuration space is 0x20013000 and the controller >>>> address for configuration space is 0x13000. The controller address should >>> be >>> >>> If above understanding is correct then: >>> >>> Aren't these addresses(0x20013000 and 0x13000) from mem space >>> instead of configuration space. >> >> Sorry. I didn't get you. Configuration space is different from mem space and IO >> space. We specify only the configuration space in "reg", the IO space and >> memory space should be specified in ranges. >> >> In my case >> configuration space range: 0x20001000 - 0x20002fff >> IO space range: 0x20003000 - 0x20012fff >> Mem space range: 0x20013000 - 0x2fffffff >> >> Here only the configuration space is obtained from 'reg' and 'IO' and 'MEM' >> space is obtained from ranges. >>> >>> If yes, then how can you get two addresses (CPU and Controller address) >>> from reg property for configuration space? >> >> I used platform_get_resource_byname() to get CPU address and of_get_address() >> to get the untranslated controller address. > > This is what I am not able to understand that how does > platform_get_resource_byname gives correct CPU address from reg = > <0x1000 0x2000>? > > cfg_res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "config"); > > how cfg_res->start is now 0x20001000? Shouldn't cfg_res->start be > 0x1000? > > What am I missing? IIUC, converting to the cpu address happens long back when the platform device is created from dt node. See if the following makes sense to you. starting from drivers/of/platform.c of_device_alloc() -> of_address_to_resource() -> __of_address_to_resource() -> of_translate_address() -> __of_translate_address() -> of_translate_one() -> of_bus_default_translate() So the 'resource' in 'struct platform_device' already holds the translated address. platform_get_resource_byname() just returns the resource from this platform device. Cheers Kishon -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html