xref: /openbmc/qemu/hw/misc/unimp.c (revision 6fdc5bc1)
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/sysbus.h"
16 #include "hw/misc/unimp.h"
17 #include "qemu/log.h"
18 #include "qemu/module.h"
19 #include "qapi/error.h"
20 
21 static uint64_t unimp_read(void *opaque, hwaddr offset, unsigned size)
22 {
23     UnimplementedDeviceState *s = UNIMPLEMENTED_DEVICE(opaque);
24 
25     qemu_log_mask(LOG_UNIMP, "%s: unimplemented device read  "
26                   "(size %d, offset 0x%0*" HWADDR_PRIx ")\n",
27                   s->name, size, s->offset_fmt_width, offset);
28     return 0;
29 }
30 
31 static void unimp_write(void *opaque, hwaddr offset,
32                         uint64_t value, unsigned size)
33 {
34     UnimplementedDeviceState *s = UNIMPLEMENTED_DEVICE(opaque);
35 
36     qemu_log_mask(LOG_UNIMP, "%s: unimplemented device write "
37                   "(size %d, offset 0x%0*" HWADDR_PRIx
38                   ", value 0x%0*" PRIx64 ")\n",
39                   s->name, size, s->offset_fmt_width, offset, size << 1, value);
40 }
41 
42 static const MemoryRegionOps unimp_ops = {
43     .read = unimp_read,
44     .write = unimp_write,
45     .impl.min_access_size = 1,
46     .impl.max_access_size = 8,
47     .valid.min_access_size = 1,
48     .valid.max_access_size = 8,
49     .endianness = DEVICE_NATIVE_ENDIAN,
50 };
51 
52 static void unimp_realize(DeviceState *dev, Error **errp)
53 {
54     UnimplementedDeviceState *s = UNIMPLEMENTED_DEVICE(dev);
55 
56     if (s->size == 0) {
57         error_setg(errp, "property 'size' not specified or zero");
58         return;
59     }
60 
61     if (s->name == NULL) {
62         error_setg(errp, "property 'name' not specified");
63         return;
64     }
65 
66     s->offset_fmt_width = DIV_ROUND_UP(64 - clz64(s->size - 1), 4);
67 
68     memory_region_init_io(&s->iomem, OBJECT(s), &unimp_ops, s,
69                           s->name, s->size);
70     sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->iomem);
71 }
72 
73 static Property unimp_properties[] = {
74     DEFINE_PROP_UINT64("size", UnimplementedDeviceState, size, 0),
75     DEFINE_PROP_STRING("name", UnimplementedDeviceState, name),
76     DEFINE_PROP_END_OF_LIST(),
77 };
78 
79 static void unimp_class_init(ObjectClass *klass, void *data)
80 {
81     DeviceClass *dc = DEVICE_CLASS(klass);
82 
83     dc->realize = unimp_realize;
84     device_class_set_props(dc, unimp_properties);
85 }
86 
87 static const TypeInfo unimp_info = {
88     .name = TYPE_UNIMPLEMENTED_DEVICE,
89     .parent = TYPE_SYS_BUS_DEVICE,
90     .instance_size = sizeof(UnimplementedDeviceState),
91     .class_init = unimp_class_init,
92 };
93 
94 static void unimp_register_types(void)
95 {
96     type_register_static(&unimp_info);
97 }
98 
99 type_init(unimp_register_types)
100