1 MC_SETPROP(9E) Driver Entry Points MC_SETPROP(9E)
2
3 NAME
4 mc_setprop - set device properties
5
6 SYNOPSIS
7 #include <sys/mac_provider.h>
8
9 int
10 prefix_m_setprop(void *driver, const char *pr_name, mac_prop_id_t pr_num,
11 uint_t pr_valsize, const void *pr_val);
12
13 INTERFACE LEVEL
14 illumos DDI specific
15
16 PARAMETERS
17 driver A pointer to the driver's private data that was passed in
18 via the m_pdata member of the mac_register(9S) structure to
19 the mac_register(9F) function.
20
21 pr_name A null-terminated string that contains the name of the
22 property.
23
24 pr_num A constant that is used to identify the property.
25
26 pr_valsize A value that indicates the size in bytes of pr_val.
27
28 pr_val A pointer to a pr_valsize byte buffer that contains the new
29 value of the property.
30
31 DESCRIPTION
32 The mc_setprop() entry point is used to set the value of a given device's
33 property from the copy stored in pr_val.
34
35 When the mc_setprop() entry point is called, the driver needs to first
36 identify the property. The set of possible properties and their meaning
37 is listed in the PROPERTIES section of mac(9E). It should identify the
38 property based on the value of pr_num. Most drivers will use a switch
39 statement and for any property that it supports it should then check if
40 the value in pr_valsize is sufficient for the property, comparing it to
41 the minimum size listed for the property in mac(9E). If it is not, then
42 it should return an error. Otherwise, it should update the property
43 based on the value in pr_val. When an unknown or unsupported property is
44 encountered, generally the default case of the switch statement, the
45 device driver should return an error.
46
47 The special property MAC_PROP_PRIVATE indicates that this is a device
48 driver specific private property. The device driver must then look at
49 the value of the pr_name argument and use strcmp(9F) on it, comparing it
50 to each of its private properties to identify which one it is.
51
52 Not all properties are supposed to be writable. Some devices may opt to
53 not allow a property that is designated as read/write to be set. When
54 such a property is encountered, the driver should return the appropriate
55 error.
56
57 The device driver can access its device soft state by casting the device
58 pointer to the appropriate structure. As this may be called while other
59 operations are ongoing, the device driver should employ the appropriate
60 locking while writing the properties.
61
62 RETURN VALUES
63 Upon successful completion, the device driver should have copied the
64 value of the property into pr_val and return 0. Otherwise, a positive
65 error should be returned to indicate failure.
66
67 EXAMPLES
68 The following examples shows how a device driver might structure its
69 mc_setprop() entry point.
70
71 #include <sys/mac_provider.h>
72
73 /*
74 * Note, this example merely shows the structure of this function.
75 * Different devices will manage their state in different ways. Like other
76 * examples, this assumes that the device has state in a structure called
77 * example_t and that there is a lock which keeps track of that state.
78 *
79 * For the purpose of this example, we assume that this device supports 100 Mb,
80 * 1 GB, and 10 Gb full duplex speeds.
81 */
82
83 static int
84 example_m_setprop(void *arg, const char *pr_name, mac_prop_id_t pr_num,
85 uint_t pr_valsize, const void *pr_val)
86 {
87 uint32_t new_mtu;
88 int ret = 0;
89 example_t *ep = arg;
90
91 mutex_enter(&ep->ep_lock);
92 switch (pr_num) {
93 /*
94 * These represent properties that can never be changed, regardless of
95 * the type of PHY on the device (copper, fiber, etc.)
96 */
97 case MAC_PROP_DUPLEX:
98 case MAC_PROP_SPEED:
99 case MAC_PROP_STATUS:
100 case MAC_PROP_ADV_100FDX_CAP:
101 case MAC_PROP_ADV_1000FDX_CAP:
102 case MAC_PROP_ADV_10GFDX_CAP:
103 ret = ENOTSUP;
104 break;
105
106 /*
107 * These EN properties are used to control the advertised speeds of the
108 * device. For this example, we assume that this device does not have a
109 * copper phy, at which point auto-negotiation and the speeds in
110 * question cannot be changed. These are called out separately as they
111 * should be controllable for copper based devices or it may need to be
112 * conditional depending on the type of phy present.
113 */
114 case MAC_PROP_EN_100FDX_CAP:
115 case MAC_PROP_EN_1000FDX_CAP:
116 case MAC_PROP_EN_10GFDX_CAP:
117 case MAC_PROP_AUTONEG:
118 ret = ENOTSUP;
119 break;
120
121 case MAC_PROP_MTU:
122 if (pr_valsize < sizeof (uint32_t)) {
123 ret = EOVERFLOW;
124 break;
125 }
126 bcopy(&new_mtu, pr_val, sizeof (uint32_t));
127
128 if (new_mtu < ep->ep_min_mtu ||
129 new_mtu > ep->ep_max_mtu) {
130 ret = EINVAL;
131 break;
132 }
133
134 /*
135 * We first ask MAC to update the MTU before we do anything.
136 * This may fail. It returns zero on success. The
137 * example_update_mtu function does device specific updates to
138 * ensure that the MTU on the device is updated and any internal
139 * data structures are up to date.
140 */
141 ret = mac_maxdsu_update(&ep->ep_mac_hdl, new_mtu);
142 if (ret == 0) {
143 example_update_mtu(ep, new_mtu);
144 }
145 break;
146
147 /*
148 * Devices may have their own private properties. If they do, they
149 * should not return ENOTSUP, but instead see if it's a property they
150 * recognize and handle it similar to those above. If it doesn't
151 * recognize the name, then it should return ENOTSUP.
152 */
153 case MAC_PROP_PRIVATE:
154 ret = ENOTSUP;
155 break;
156
157 default:
158 ret = ENOTSUP;
159 break;
160 }
161 mutex_exit(&ep->ep_lock);
162
163 return (ret);
164 }
165
166 ERRORS
167 The device driver may return one of the following errors. While this
168 list is not intended to be exhaustive, it is recommended to use one of
169 these if possible.
170
171 EINVAL The contents of pr_val are outside the valid range for
172 the property.
173
174 ENOTSUP This error should be used whenever an unknown or
175 unsupported property is encountered. It should also
176 be used when the property is not writable.
177
178 EOVERFLOW This error should be used when pr_valsize is smaller
179 than the required size for a given value.
180
181 EBUSY This error should be used when a property can't be set
182 because the device has started. Note that device
183 driver writers are encouraged to design device drivers
184 such that this error is not possible.
185
186 ECANCELLED The device is in a state that does not allow it to
187 handle data; for example, it's suspended.
188
189 SEE ALSO
190 mac(9E), mac_register(9F), strcmp(9F), mac_register(9S)
191
192 illumos February 15, 2020 illumos