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9d68bf56 SG |
1 | /* |
2 | * Microbit stub for Nordic Semiconductor nRF51 SoC Two-Wire Interface | |
3 | * http://infocenter.nordicsemi.com/pdf/nRF51_RM_v3.0.1.pdf | |
4 | * | |
5 | * This is a microbit-specific stub for the TWI controller on the nRF51 SoC. | |
6 | * We don't emulate I2C devices but the firmware probes the | |
7 | * accelerometer/magnetometer on startup and panics if they are not found. | |
8 | * Therefore we stub out the probing. | |
9 | * | |
10 | * In the future this file could evolve into a full nRF51 TWI controller | |
11 | * device. | |
12 | * | |
13 | * Copyright 2018 Steffen Görtz <contrib@steffen-goertz.de> | |
14 | * Copyright 2019 Red Hat, Inc. | |
15 | * | |
16 | * This code is licensed under the GPL version 2 or later. See | |
17 | * the COPYING file in the top-level directory. | |
18 | */ | |
19 | ||
20 | #include "qemu/osdep.h" | |
21 | #include "qemu/log.h" | |
0b8fa32f | 22 | #include "qemu/module.h" |
9d68bf56 | 23 | #include "hw/i2c/microbit_i2c.h" |
d6454270 | 24 | #include "migration/vmstate.h" |
9d68bf56 SG |
25 | |
26 | static const uint32_t twi_read_sequence[] = {0x5A, 0x5A, 0x40}; | |
27 | ||
28 | static uint64_t microbit_i2c_read(void *opaque, hwaddr addr, unsigned int size) | |
29 | { | |
30 | MicrobitI2CState *s = opaque; | |
31 | uint64_t data = 0x00; | |
32 | ||
33 | switch (addr) { | |
34 | case NRF51_TWI_EVENT_STOPPED: | |
35 | data = 0x01; | |
36 | break; | |
37 | case NRF51_TWI_EVENT_RXDREADY: | |
38 | data = 0x01; | |
39 | break; | |
40 | case NRF51_TWI_EVENT_TXDSENT: | |
41 | data = 0x01; | |
42 | break; | |
43 | case NRF51_TWI_REG_RXD: | |
44 | data = twi_read_sequence[s->read_idx]; | |
45 | if (s->read_idx < G_N_ELEMENTS(twi_read_sequence)) { | |
46 | s->read_idx++; | |
47 | } | |
48 | break; | |
49 | default: | |
50 | data = s->regs[addr / sizeof(s->regs[0])]; | |
51 | break; | |
52 | } | |
53 | ||
54 | qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " [%u] = %" PRIx32 "\n", | |
55 | __func__, addr, size, (uint32_t)data); | |
56 | ||
57 | ||
58 | return data; | |
59 | } | |
60 | ||
61 | static void microbit_i2c_write(void *opaque, hwaddr addr, uint64_t data, | |
62 | unsigned int size) | |
63 | { | |
64 | MicrobitI2CState *s = opaque; | |
65 | ||
66 | qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " <- 0x%" PRIx64 " [%u]\n", | |
67 | __func__, addr, data, size); | |
68 | s->regs[addr / sizeof(s->regs[0])] = data; | |
69 | } | |
70 | ||
71 | static const MemoryRegionOps microbit_i2c_ops = { | |
72 | .read = microbit_i2c_read, | |
73 | .write = microbit_i2c_write, | |
74 | .endianness = DEVICE_LITTLE_ENDIAN, | |
75 | .impl.min_access_size = 4, | |
76 | .impl.max_access_size = 4, | |
77 | }; | |
78 | ||
79 | static const VMStateDescription microbit_i2c_vmstate = { | |
80 | .name = TYPE_MICROBIT_I2C, | |
81 | .version_id = 1, | |
82 | .minimum_version_id = 1, | |
83 | .fields = (VMStateField[]) { | |
84 | VMSTATE_UINT32_ARRAY(regs, MicrobitI2CState, MICROBIT_I2C_NREGS), | |
85 | VMSTATE_UINT32(read_idx, MicrobitI2CState), | |
86 | }, | |
87 | }; | |
88 | ||
89 | static void microbit_i2c_reset(DeviceState *dev) | |
90 | { | |
91 | MicrobitI2CState *s = MICROBIT_I2C(dev); | |
92 | ||
93 | memset(s->regs, 0, sizeof(s->regs)); | |
94 | s->read_idx = 0; | |
95 | } | |
96 | ||
97 | static void microbit_i2c_realize(DeviceState *dev, Error **errp) | |
98 | { | |
99 | SysBusDevice *sbd = SYS_BUS_DEVICE(dev); | |
100 | MicrobitI2CState *s = MICROBIT_I2C(dev); | |
101 | ||
102 | memory_region_init_io(&s->iomem, OBJECT(s), µbit_i2c_ops, s, | |
103 | "microbit.twi", NRF51_TWI_SIZE); | |
104 | sysbus_init_mmio(sbd, &s->iomem); | |
105 | } | |
106 | ||
107 | static void microbit_i2c_class_init(ObjectClass *klass, void *data) | |
108 | { | |
109 | DeviceClass *dc = DEVICE_CLASS(klass); | |
110 | ||
111 | dc->vmsd = µbit_i2c_vmstate; | |
112 | dc->reset = microbit_i2c_reset; | |
113 | dc->realize = microbit_i2c_realize; | |
114 | dc->desc = "Microbit I2C controller"; | |
115 | } | |
116 | ||
117 | static const TypeInfo microbit_i2c_info = { | |
118 | .name = TYPE_MICROBIT_I2C, | |
119 | .parent = TYPE_SYS_BUS_DEVICE, | |
120 | .instance_size = sizeof(MicrobitI2CState), | |
121 | .class_init = microbit_i2c_class_init, | |
122 | }; | |
123 | ||
124 | static void microbit_i2c_register_types(void) | |
125 | { | |
126 | type_register_static(µbit_i2c_info); | |
127 | } | |
128 | ||
129 | type_init(microbit_i2c_register_types) |