xref: /openbmc/qemu/hw/misc/unimp.c (revision 500eb6db)
1 /* "Unimplemented" device
2  *
3  * This is a dummy device which accepts and logs all accesses.
4  * It's useful for stubbing out regions of an SoC or board
5  * map which correspond to devices that have not yet been
6  * implemented. This is often sufficient to placate initial
7  * guest device driver probing such that the system will
8  * come up.
9  *
10  * Copyright Linaro Limited, 2017
11  * Written by Peter Maydell
12  */
13 
14 #include "qemu/osdep.h"
15 #include "hw/hw.h"
16 #include "hw/sysbus.h"
17 #include "hw/misc/unimp.h"
18 #include "qemu/log.h"
19 #include "qemu/module.h"
20 #include "qapi/error.h"
21 
22 static uint64_t unimp_read(void *opaque, hwaddr offset, unsigned size)
23 {
24     UnimplementedDeviceState *s = UNIMPLEMENTED_DEVICE(opaque);
25 
26     qemu_log_mask(LOG_UNIMP, "%s: unimplemented device read "
27                   "(size %d, offset 0x%" HWADDR_PRIx ")\n",
28                   s->name, size, offset);
29     return 0;
30 }
31 
32 static void unimp_write(void *opaque, hwaddr offset,
33                         uint64_t value, unsigned size)
34 {
35     UnimplementedDeviceState *s = UNIMPLEMENTED_DEVICE(opaque);
36 
37     qemu_log_mask(LOG_UNIMP, "%s: unimplemented device write "
38                   "(size %d, value 0x%" PRIx64
39                   ", offset 0x%" HWADDR_PRIx ")\n",
40                   s->name, size, value, offset);
41 }
42 
43 static const MemoryRegionOps unimp_ops = {
44     .read = unimp_read,
45     .write = unimp_write,
46     .impl.min_access_size = 1,
47     .impl.max_access_size = 8,
48     .valid.min_access_size = 1,
49     .valid.max_access_size = 8,
50     .endianness = DEVICE_NATIVE_ENDIAN,
51 };
52 
53 static void unimp_realize(DeviceState *dev, Error **errp)
54 {
55     UnimplementedDeviceState *s = UNIMPLEMENTED_DEVICE(dev);
56 
57     if (s->size == 0) {
58         error_setg(errp, "property 'size' not specified or zero");
59         return;
60     }
61 
62     if (s->name == NULL) {
63         error_setg(errp, "property 'name' not specified");
64         return;
65     }
66 
67     memory_region_init_io(&s->iomem, OBJECT(s), &unimp_ops, s,
68                           s->name, s->size);
69     sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->iomem);
70 }
71 
72 static Property unimp_properties[] = {
73     DEFINE_PROP_UINT64("size", UnimplementedDeviceState, size, 0),
74     DEFINE_PROP_STRING("name", UnimplementedDeviceState, name),
75     DEFINE_PROP_END_OF_LIST(),
76 };
77 
78 static void unimp_class_init(ObjectClass *klass, void *data)
79 {
80     DeviceClass *dc = DEVICE_CLASS(klass);
81 
82     dc->realize = unimp_realize;
83     dc->props = unimp_properties;
84 }
85 
86 static const TypeInfo unimp_info = {
87     .name = TYPE_UNIMPLEMENTED_DEVICE,
88     .parent = TYPE_SYS_BUS_DEVICE,
89     .instance_size = sizeof(UnimplementedDeviceState),
90     .class_init = unimp_class_init,
91 };
92 
93 static void unimp_register_types(void)
94 {
95     type_register_static(&unimp_info);
96 }
97 
98 type_init(unimp_register_types)
99