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12 .\" Copyright 2016 Joyent, Inc.
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14 .Dd November 15, 2016
15 .Dt MC_GETPROP 9E
16 .Os
17 .Sh NAME
18 .Nm mc_getprop
19 .Nd get device properties
20 .Sh SYNOPSIS
21 .In sys/mac_provider.h
22 .Ft int
23 .Fo prefix_m_getprop
24 .Fa "void *driver"
25 .Fa "const char *pr_name"
26 .Fa "mac_prop_id_t pr_num"
27 .Fa "uint_t pr_valsize"
28 .Fa "void *pr_val"
29 .Fc
30 .Sh INTERFACE LEVEL
31 illumos DDI specific
32 .Sh PARAMETERS
33 .Bl -tag -width Fa
34 .It Fa driver
35 A pointer to the driver's private data that was passed in via the
36 .Sy m_pdata
37 member of the
38 .Xr mac_register 9S
39 structure to the
40 .Xr mac_register 9F
41 function.
42 .It Fa pr_name
43 A null-terminated string that contains the name of the property.
44 .It Fa pr_num
45 A constant that is used to identify the property.
46 .It Fa pr_valsize
47 A value that indicates the size in bytes of
48 .Fa pr_val .
49 .It Fa pr_val
50 A pointer to a
51 .Fa pr_valsize
52 byte buffer that can store the property.
53 .El
54 .Sh DESCRIPTION
55 The
56 .Fn mc_getprop
57 entry point is used to obtain the value of a given device's property and
58 place it into
59 .Fa pr_val .
60 .Pp
61 When the
62 .Fn mc_getprop
63 entry point is called, the driver needs to first identify the property.
64 The set of possible properties and their meaning is listed in the
65 .Sx PROPERTIES
66 section of
67 .Xr mac 9E .
68 It should identify the property based on the value of
69 .Fa pr_num .
70 Most drivers will use a
71 .Sy switch
72 statement and for any property that it supports it should then check if
73 the value in
74 .Fa pr_valsize
75 is sufficient for the property, comparing it to the minimum size
76 listed for the property in
77 .Xr mac 9E .
78 If it is not, then it should return an error.
79 Otherwise, it should copy the property's value into
80 .Fa pr_val .
81 When an unknown or unsupported
82 property is encountered, generally the
83 .Sy default
84 case of the switch statement, the device driver should return an error.
85 .Pp
86 The special property
87 .Sy MAC_PROP_PRIVATE
88 indicates that this is a device driver specific private property.
89 The device driver must then look at the value of the
90 .Fa pr_name
91 argument and use
92 .Xr strcmp 9F
93 on it, comparing it to each of its private (bounded-size) properties to
94 identify which one it is.
95 .Pp
96 At this time, private properties are limited to being string based properties.
97 If other types of property values are used, they will not be rendered
98 correctly by
99 .Xr dladm 1M .
100 .Pp
101 The device
102 driver can access its device soft state by casting the
103 .Fa device
104 pointer to the appropriate structure.
105 As this may be called while other operations are ongoing, the device driver
106 should employ the appropriate locking while reading the properties.
107 .Sh CONTEXT
108 The
109 .Fn mc_getprop
110 function is generally called from
111 .Sy kernel
112 context.
113 .Sh RETURN VALUES
114 Upon successful completion, the device driver should have copied the
115 value of the property into
116 .Fa pr_val
117 and return
118 .Sy 0 .
119 Otherwise, a positive error should be returned to indicate failure.
120 .Sh EXAMPLES
121 The following example shows how a device driver might structure its
122 .Fn mc_getprop
123 entry point.
124 .Bd -literal
125 #include <sys/mac_provider.h>
126
127 /*
128 * Note, this example merely shows the structure of this function.
129 * Different devices will manage their state in different ways. Like other
130 * examples, this assumes that the device has state in a structure called
131 * example_t and that there is a lock which keeps track of that state.
132 */
133 static char *example_priv_props[] = {
134 "_rx_intr_throttle",
135 "_tx_intr_throttle",
136 NULL
137 };
138
139 static int
140 example_m_getprop_private(example_t *ep, const char *pr_name, uint_t pr_valsize,
141 void *pr_val)
142 {
143 uint32_t val;
144
145 ASSERT(MUTEX_HELD(&ep->ep_lock));
146 if (strcmp(pr_name, example_priv_props[0] == 0) {
147 val = ep->ep_rx_itr;
148 } else if (strcmp(pr_name, exampe_priv_props[1] == 0) {
149 val = ep->ep_tx_itr;
150 } else {
151 return (ENOTSUP);
152 }
153
154 /*
155 * Due to issues in the GLDv3, these must be returned as string
156 * properties.
157 */
158 if (snprintf(pr_val, pr_valsize, "%d", val) >= pr_valsize)
159 return (EOVERFLOW);
160
161 return (0);
162 }
163
164 static int
165 example_m_getprop(void *arg, const char *pr_name, mac_prop_id_t pr_num,
166 uint_t pr_valsize, void *pr_val)
167 {
168 int ret = 0;
169 uint64_t speed;
170 example_t *ep = arg;
171
172 mutex_enter(&ep->ep_lock);
173
174 /*
175 * This only handles a subset of the properties that exist on the
176 * system. A proper driver will need to handle more. See mac(9E) for a
177 * full property list.
178 */
179 switch (pr_num) {
180 case MAC_PROP_DUPLEX:
181 if (pr_valsize < sizeof (link_duplex_t)) {
182 ret = EOVERFLOW;
183 break;
184 }
185 bcopy(ep->ep_link_duplex, pr_val, sizeof (link_duplex_t));
186 case MAC_PROP_SPEED:
187 if (pr_valsize < sizeof (uint64_t)) {
188 ret = EOVERFLOW;
189 break;
190 }
191 /*
192 * The link speed is stored in Mbits/s in this driver and is
193 * expected in bits/s.
194 */
195 speed = ep->ep_link_speed * 1000000ULL;
196 bcopy(&speed, pr_val, sizeof (speed));
197 break;
198 case MAC_PROP_MTU:
199 if (pr_valsize < sizeof (uint32_t)) {
200 ret = EOVERFLOW;
201 break;
202 }
203 bcopy(&ep->ep_mtu, pr_val, sizeof (speed));
204 break;
205 case MAC_PROP_PRIVATE:
206 ret = example_m_getprop_private(ep, pr_name, pr_valsize,
207 pr_val);
208 break;
209 default:
210 ret = ENOTSUP;
211 break;
212 }
213
214 mutex_exit(&ep->ep_lock);
215
216 return (ret);
217 }
218 .Ed
219 .Sh ERRORS
220 The device driver may return one of the following errors.
221 While this list is not intended to be exhaustive, it is recommended to use one
222 of these if possible.
223 .Bl -tag -width Er
224 .It Er ENOTSUP
225 This error should be used whenever an unknown or unsupported property is
226 encountered.
227 .It Er EOVERFLOW
228 This error should be used when
229 .Fa pr_valsize
230 is smaller than the required size for a given value.
231 .El
232 .Sh SEE ALSO
233 .Xr mac 9E ,
234 .Xr mac_register 9F ,
235 .Xr strcmp 9F ,
236 .Xr mac_register 9S