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| -rw-r--r-- | Documentation/networking/dm9000.txt | 167 |
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diff --git a/Documentation/networking/dm9000.txt b/Documentation/networking/dm9000.txt new file mode 100644 index 00000000000..65df3dea556 --- /dev/null +++ b/Documentation/networking/dm9000.txt @@ -0,0 +1,167 @@ +DM9000 Network driver +===================== + +Copyright 2008 Simtec Electronics, + Ben Dooks <ben@simtec.co.uk> <ben-linux@fluff.org> + + +Introduction +------------ + +This file describes how to use the DM9000 platform-device based network driver +that is contained in the files drivers/net/dm9000.c and drivers/net/dm9000.h. + +The driver supports three DM9000 variants, the DM9000E which is the first chip +supported as well as the newer DM9000A and DM9000B devices. It is currently +maintained and tested by Ben Dooks, who should be CC: to any patches for this +driver. + + +Defining the platform device +---------------------------- + +The minimum set of resources attached to the platform device are as follows: + + 1) The physical address of the address register + 2) The physical address of the data register + 3) The IRQ line the device's interrupt pin is connected to. + +These resources should be specified in that order, as the ordering of the +two address regions is important (the driver expects these to be address +and then data). + +An example from arch/arm/mach-s3c2410/mach-bast.c is: + +static struct resource bast_dm9k_resource[] = { + [0] = { + .start = S3C2410_CS5 + BAST_PA_DM9000, + .end = S3C2410_CS5 + BAST_PA_DM9000 + 3, + .flags = IORESOURCE_MEM, + }, + [1] = { + .start = S3C2410_CS5 + BAST_PA_DM9000 + 0x40, + .end = S3C2410_CS5 + BAST_PA_DM9000 + 0x40 + 0x3f, + .flags = IORESOURCE_MEM, + }, + [2] = { + .start = IRQ_DM9000, + .end = IRQ_DM9000, + .flags = IORESOURCE_IRQ | IORESOURCE_IRQ_HIGHLEVEL, + } +}; + +static struct platform_device bast_device_dm9k = { + .name = "dm9000", + .id = 0, + .num_resources = ARRAY_SIZE(bast_dm9k_resource), + .resource = bast_dm9k_resource, +}; + +Note the setting of the IRQ trigger flag in bast_dm9k_resource[2].flags, +as this will generate a warning if it is not present. The trigger from +the flags field will be passed to request_irq() when registering the IRQ +handler to ensure that the IRQ is setup correctly. + +This shows a typical platform device, without the optional configuration +platform data supplied. The next example uses the same resources, but adds +the optional platform data to pass extra configuration data: + +static struct dm9000_plat_data bast_dm9k_platdata = { + .flags = DM9000_PLATF_16BITONLY, +}; + +static struct platform_device bast_device_dm9k = { + .name = "dm9000", + .id = 0, + .num_resources = ARRAY_SIZE(bast_dm9k_resource), + .resource = bast_dm9k_resource, + .dev = { + .platform_data = &bast_dm9k_platdata, + } +}; + +The platform data is defined in include/linux/dm9000.h and described below. + + +Platform data +------------- + +Extra platform data for the DM9000 can describe the IO bus width to the +device, whether or not an external PHY is attached to the device and +the availability of an external configuration EEPROM. + +The flags for the platform data .flags field are as follows: + +DM9000_PLATF_8BITONLY + + The IO should be done with 8bit operations. + +DM9000_PLATF_16BITONLY + + The IO should be done with 16bit operations. + +DM9000_PLATF_32BITONLY + + The IO should be done with 32bit operations. + +DM9000_PLATF_EXT_PHY + + The chip is connected to an external PHY. + +DM9000_PLATF_NO_EEPROM + + This can be used to signify that the board does not have an + EEPROM, or that the EEPROM should be hidden from the user. + +DM9000_PLATF_SIMPLE_PHY + + Switch to using the simpler PHY polling method which does not + try and read the MII PHY state regularly. This is only available + when using the internal PHY. See the section on link state polling + for more information. + + The config symbol DM9000_FORCE_SIMPLE_PHY_POLL, Kconfig entry + "Force simple NSR based PHY polling" allows this flag to be + forced on at build time. + + +PHY Link state polling +---------------------- + +The driver keeps track of the link state and informs the network core +about link (carrier) availablilty. This is managed by several methods +depending on the version of the chip and on which PHY is being used. + +For the internal PHY, the original (and currently default) method is +to read the MII state, either when the status changes if we have the +necessary interrupt support in the chip or every two seconds via a +periodic timer. + +To reduce the overhead for the internal PHY, there is now the option +of using the DM9000_FORCE_SIMPLE_PHY_POLL config, or DM9000_PLATF_SIMPLE_PHY +platform data option to read the summary information without the +expensive MII accesses. This method is faster, but does not print +as much information. + +When using an external PHY, the driver currently has to poll the MII +link status as there is no method for getting an interrupt on link change. + + +DM9000A / DM9000B +----------------- + +These chips are functionally similar to the DM9000E and are supported easily +by the same driver. The features are: + + 1) Interrupt on internal PHY state change. This means that the periodic + polling of the PHY status may be disabled on these devices when using + the internal PHY. + + 2) TCP/UDP checksum offloading, which the driver does not currently support. + + +ethtool +------- + +The driver supports the ethtool interface for access to the driver +state information, the PHY state and the EEPROM. |