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" |
22 | #include "qemu/module.h" |
23 | #include "hw/i2c/microbit_i2c.h" |
24 | #include "migration/vmstate.h" |
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) |
130 | |