Documentation/networking/dm9000.txt

   1 DM9000 Network driver
   2 =====================
   3
   4 Copyright 2008 Simtec Electronics,
   5           Ben Dooks <ben@simtec.co.uk> <ben-linux@fluff.org>
   6
   7
   8 Introduction
   9 ------------
  10
  11 This file describes how to use the DM9000 platform-device based network driver
  12 that is contained in the files drivers/net/dm9000.c and drivers/net/dm9000.h.
  13
  14 The driver supports three DM9000 variants, the DM9000E which is the first chip
  15 supported as well as the newer DM9000A and DM9000B devices. It is currently
  16 maintained and tested by Ben Dooks, who should be CC: to any patches for this
  17 driver.
  18
  19
  20 Defining the platform device
  21 ----------------------------
  22
  23 The minimum set of resources attached to the platform device are as follows:
  24
  25     1) The physical address of the address register
  26     2) The physical address of the data register
  27     3) The IRQ line the device's interrupt pin is connected to.
  28
  29 These resources should be specified in that order, as the ordering of the
  30 two address regions is important (the driver expects these to be address
  31 and then data).
  32
  33 An example from arch/arm/mach-s3c2410/mach-bast.c is:
  34
  35 static struct resource bast_dm9k_resource[] = {
  36         [0] = {
  37                 .start = S3C2410_CS5 + BAST_PA_DM9000,
  38                 .end   = S3C2410_CS5 + BAST_PA_DM9000 + 3,
  39                 .flags = IORESOURCE_MEM,
  40         },
  41         [1] = {
  42                 .start = S3C2410_CS5 + BAST_PA_DM9000 + 0x40,
  43                 .end   = S3C2410_CS5 + BAST_PA_DM9000 + 0x40 + 0x3f,
  44                 .flags = IORESOURCE_MEM,
  45         },
  46         [2] = {
  47                 .start = IRQ_DM9000,
  48                 .end   = IRQ_DM9000,
  49                 .flags = IORESOURCE_IRQ | IORESOURCE_IRQ_HIGHLEVEL,
  50         }
  51 };
  52
  53 static struct platform_device bast_device_dm9k = {
  54         .name           = "dm9000",
  55         .id             = 0,
  56         .num_resources  = ARRAY_SIZE(bast_dm9k_resource),
  57         .resource       = bast_dm9k_resource,
  58 };
  59
  60 Note the setting of the IRQ trigger flag in bast_dm9k_resource[2].flags,
  61 as this will generate a warning if it is not present. The trigger from
  62 the flags field will be passed to request_irq() when registering the IRQ
  63 handler to ensure that the IRQ is setup correctly.
  64
  65 This shows a typical platform device, without the optional configuration
  66 platform data supplied. The next example uses the same resources, but adds
  67 the optional platform data to pass extra configuration data:
  68
  69 static struct dm9000_plat_data bast_dm9k_platdata = {
  70         .flags          = DM9000_PLATF_16BITONLY,
  71 };
  72
  73 static struct platform_device bast_device_dm9k = {
  74         .name           = "dm9000",
  75         .id             = 0,
  76         .num_resources  = ARRAY_SIZE(bast_dm9k_resource),
  77         .resource       = bast_dm9k_resource,
  78         .dev            = {
  79                 .platform_data = &bast_dm9k_platdata,
  80         }
  81 };
  82
  83 The platform data is defined in include/linux/dm9000.h and described below.
  84
  85
  86 Platform data
  87 -------------
  88
  89 Extra platform data for the DM9000 can describe the IO bus width to the
  90 device, whether or not an external PHY is attached to the device and
  91 the availability of an external configuration EEPROM.
  92
  93 The flags for the platform data .flags field are as follows:
  94
  95 DM9000_PLATF_8BITONLY
  96
  97         The IO should be done with 8bit operations.
  98
  99 DM9000_PLATF_16BITONLY
 100
 101         The IO should be done with 16bit operations.
 102
 103 DM9000_PLATF_32BITONLY
 104
 105         The IO should be done with 32bit operations.
 106
 107 DM9000_PLATF_EXT_PHY
 108
 109         The chip is connected to an external PHY.
 110
 111 DM9000_PLATF_NO_EEPROM
 112
 113         This can be used to signify that the board does not have an
 114         EEPROM, or that the EEPROM should be hidden from the user.
 115
 116 DM9000_PLATF_SIMPLE_PHY
 117
 118         Switch to using the simpler PHY polling method which does not
 119         try and read the MII PHY state regularly. This is only available
 120         when using the internal PHY. See the section on link state polling
 121         for more information.
 122
 123         The config symbol DM9000_FORCE_SIMPLE_PHY_POLL, Kconfig entry
 124         "Force simple NSR based PHY polling" allows this flag to be
 125         forced on at build time.
 126
 127
 128 PHY Link state polling
 129 ----------------------
 130
 131 The driver keeps track of the link state and informs the network core
 132 about link (carrier) availability. This is managed by several methods
 133 depending on the version of the chip and on which PHY is being used.
 134
 135 For the internal PHY, the original (and currently default) method is
 136 to read the MII state, either when the status changes if we have the
 137 necessary interrupt support in the chip or every two seconds via a
 138 periodic timer.
 139
 140 To reduce the overhead for the internal PHY, there is now the option
 141 of using the DM9000_FORCE_SIMPLE_PHY_POLL config, or DM9000_PLATF_SIMPLE_PHY
 142 platform data option to read the summary information without the
 143 expensive MII accesses. This method is faster, but does not print
 144 as much information.
 145
 146 When using an external PHY, the driver currently has to poll the MII
 147 link status as there is no method for getting an interrupt on link change.
 148
 149
 150 DM9000A / DM9000B
 151 -----------------
 152
 153 These chips are functionally similar to the DM9000E and are supported easily
 154 by the same driver. The features are:
 155
 156    1) Interrupt on internal PHY state change. This means that the periodic
 157       polling of the PHY status may be disabled on these devices when using
 158       the internal PHY.
 159
 160    2) TCP/UDP checksum offloading, which the driver does not currently support.
 161
 162
 163 ethtool
 164 -------
 165
 166 The driver supports the ethtool interface for access to the driver
 167 state information, the PHY state and the EEPROM.