1 .. SPDX-License-Identifier: GPL-2.0
2
3 =====================
4 DM9000 Network driver
5 =====================
6
7 Copyright 2008 Simtec Electronics,
8
9 Ben Dooks <ben@simtec.co.uk> <ben-linux@fluff.org>
10
11
12 Introduction
13 ------------
14
15 This file describes how to use the DM9000 platform-device based network driver
16 that is contained in the files drivers/net/dm9000.c and drivers/net/dm9000.h.
17
18 The driver supports three DM9000 variants, the DM9000E which is the first chip
19 supported as well as the newer DM9000A and DM9000B devices. It is currently
20 maintained and tested by Ben Dooks, who should be CC: to any patches for this
21 driver.
22
23
24 Defining the platform device
25 ----------------------------
26
27 The minimum set of resources attached to the platform device are as follows:
28
29 1) The physical address of the address register
30 2) The physical address of the data register
31 3) The IRQ line the device's interrupt pin is connected to.
32
33 These resources should be specified in that order, as the ordering of the
34 two address regions is important (the driver expects these to be address
35 and then data).
36
37 An example from arch/arm/mach-s3c/mach-bast.c is::
38
39 static struct resource bast_dm9k_resource[] = {
40 [0] = {
41 .start = S3C2410_CS5 + BAST_PA_DM9000,
42 .end = S3C2410_CS5 + BAST_PA_DM9000 + 3,
43 .flags = IORESOURCE_MEM,
44 },
45 [1] = {
46 .start = S3C2410_CS5 + BAST_PA_DM9000 + 0x40,
47 .end = S3C2410_CS5 + BAST_PA_DM9000 + 0x40 + 0x3f,
48 .flags = IORESOURCE_MEM,
49 },
50 [2] = {
51 .start = IRQ_DM9000,
52 .end = IRQ_DM9000,
53 .flags = IORESOURCE_IRQ | IORESOURCE_IRQ_HIGHLEVEL,
54 }
55 };
56
57 static struct platform_device bast_device_dm9k = {
58 .name = "dm9000",
59 .id = 0,
60 .num_resources = ARRAY_SIZE(bast_dm9k_resource),
61 .resource = bast_dm9k_resource,
62 };
63
64 Note the setting of the IRQ trigger flag in bast_dm9k_resource[2].flags,
65 as this will generate a warning if it is not present. The trigger from
66 the flags field will be passed to request_irq() when registering the IRQ
67 handler to ensure that the IRQ is setup correctly.
68
69 This shows a typical platform device, without the optional configuration
70 platform data supplied. The next example uses the same resources, but adds
71 the optional platform data to pass extra configuration data::
72
73 static struct dm9000_plat_data bast_dm9k_platdata = {
74 .flags = DM9000_PLATF_16BITONLY,
75 };
76
77 static struct platform_device bast_device_dm9k = {
78 .name = "dm9000",
79 .id = 0,
80 .num_resources = ARRAY_SIZE(bast_dm9k_resource),
81 .resource = bast_dm9k_resource,
82 .dev = {
83 .platform_data = &bast_dm9k_platdata,
84 }
85 };
86
87 The platform data is defined in include/linux/dm9000.h and described below.
88
89
90 Platform data
91 -------------
92
93 Extra platform data for the DM9000 can describe the IO bus width to the
94 device, whether or not an external PHY is attached to the device and
95 the availability of an external configuration EEPROM.
96
97 The flags for the platform data .flags field are as follows:
98
99 DM9000_PLATF_8BITONLY
100
101 The IO should be done with 8bit operations.
102
103 DM9000_PLATF_16BITONLY
104
105 The IO should be done with 16bit operations.
106
107 DM9000_PLATF_32BITONLY
108
109 The IO should be done with 32bit operations.
110
111 DM9000_PLATF_EXT_PHY
112
113 The chip is connected to an external PHY.
114
115 DM9000_PLATF_NO_EEPROM
116
117 This can be used to signify that the board does not have an
118 EEPROM, or that the EEPROM should be hidden from the user.
119
120 DM9000_PLATF_SIMPLE_PHY
121
122 Switch to using the simpler PHY polling method which does not
123 try and read the MII PHY state regularly. This is only available
124 when using the internal PHY. See the section on link state polling
125 for more information.
126
127 The config symbol DM9000_FORCE_SIMPLE_PHY_POLL, Kconfig entry
128 "Force simple NSR based PHY polling" allows this flag to be
129 forced on at build time.
130
131
132 PHY Link state polling
133 ----------------------
134
135 The driver keeps track of the link state and informs the network core
136 about link (carrier) availability. This is managed by several methods
137 depending on the version of the chip and on which PHY is being used.
138
139 For the internal PHY, the original (and currently default) method is
140 to read the MII state, either when the status changes if we have the
141 necessary interrupt support in the chip or every two seconds via a
142 periodic timer.
143
144 To reduce the overhead for the internal PHY, there is now the option
145 of using the DM9000_FORCE_SIMPLE_PHY_POLL config, or DM9000_PLATF_SIMPLE_PHY
146 platform data option to read the summary information without the
147 expensive MII accesses. This method is faster, but does not print
148 as much information.
149
150 When using an external PHY, the driver currently has to poll the MII
151 link status as there is no method for getting an interrupt on link change.
152
153
154 DM9000A / DM9000B
155 -----------------
156
157 These chips are functionally similar to the DM9000E and are supported easily
158 by the same driver. The features are:
159
160 1) Interrupt on internal PHY state change. This means that the periodic
161 polling of the PHY status may be disabled on these devices when using
162 the internal PHY.
163
164 2) TCP/UDP checksum offloading, which the driver does not currently support.
165
166
167 ethtool
168 -------
169
170 The driver supports the ethtool interface for access to the driver
171 state information, the PHY state and the EEPROM.
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