1 /*
2 * Copyright 2024 Google LLC
3 * SPDX-License-Identifier: Apache-2.0
4 */
5
6 #define DT_DRV_COMPAT microchip_mcp7940n
7
8 #include <zephyr/device.h>
9 #include <zephyr/drivers/emul.h>
10 #include <zephyr/drivers/emul_bbram.h>
11 #include <zephyr/drivers/i2c.h>
12 #include <zephyr/drivers/i2c_emul.h>
13 #include <zephyr/logging/log.h>
14
15 LOG_MODULE_DECLARE(bbram_microchip_mcp7940n, CONFIG_BBRAM_LOG_LEVEL);
16
17 #define MICROCHIP_MCP7940N_SRAM_OFFSET 0x20
18 #define MICROCHIP_MCP7940N_SRAM_SIZE 64
19 #define MICROCHIP_MCP7940N_RTCWKDAY_REGISTER_ADDRESS 0x03
20 #define MICROCHIP_MCP7940N_RTCWKDAY_VBATEN_BIT BIT(3)
21 #define MICROCHIP_MCP7940N_RTCWKDAY_PWRFAIL_BIT BIT(4)
22
23 struct mcp7940n_emul_cfg {
24 };
25
26 struct mcp7940n_emul_data {
27 uint8_t rtcwkday;
28 uint8_t data[MICROCHIP_MCP7940N_SRAM_SIZE];
29 };
30
mcp7940n_emul_init(const struct emul * target,const struct device * parent)31 static int mcp7940n_emul_init(const struct emul *target, const struct device *parent)
32 {
33 ARG_UNUSED(target);
34 ARG_UNUSED(parent);
35 return 0;
36 }
37
mcp7940n_emul_transfer_i2c(const struct emul * target,struct i2c_msg * msgs,int num_msgs,int addr)38 static int mcp7940n_emul_transfer_i2c(const struct emul *target, struct i2c_msg *msgs, int num_msgs,
39 int addr)
40 {
41 struct mcp7940n_emul_data *data = target->data;
42
43 i2c_dump_msgs_rw(target->dev, msgs, num_msgs, addr, false);
44
45 if (num_msgs < 1) {
46 LOG_ERR("Invalid number of messages: %d", num_msgs);
47 return -EIO;
48 }
49 if (FIELD_GET(I2C_MSG_READ, msgs->flags)) {
50 LOG_ERR("Unexpected read");
51 return -EIO;
52 }
53 if (msgs->len < 1) {
54 LOG_ERR("Unexpected msg0 length %d", msgs->len);
55 return -EIO;
56 }
57
58 uint8_t regn = msgs->buf[0];
59 bool is_read = FIELD_GET(I2C_MSG_READ, msgs->flags) == 1;
60 bool is_stop = FIELD_GET(I2C_MSG_STOP, msgs->flags) == 1;
61
62 if (!is_stop && !is_read) {
63 /* First message was a write with the register number, check next message */
64 msgs++;
65 is_read = FIELD_GET(I2C_MSG_READ, msgs->flags) == 1;
66 is_stop = FIELD_GET(I2C_MSG_STOP, msgs->flags) == 1;
67 }
68
69 if (is_read) {
70 /* Read data */
71 if (regn == MICROCHIP_MCP7940N_RTCWKDAY_REGISTER_ADDRESS) {
72 msgs->buf[0] = data->rtcwkday;
73 return 0;
74 }
75 if (regn >= MICROCHIP_MCP7940N_SRAM_OFFSET &&
76 regn + msgs->len <=
77 MICROCHIP_MCP7940N_SRAM_OFFSET + MICROCHIP_MCP7940N_SRAM_SIZE) {
78 for (int i = 0; i < msgs->len; ++i) {
79 msgs->buf[i] =
80 data->data[regn + i - MICROCHIP_MCP7940N_SRAM_OFFSET];
81 }
82 return 0;
83 }
84 } else {
85 /* Write data */
86 if (regn == MICROCHIP_MCP7940N_RTCWKDAY_REGISTER_ADDRESS) {
87 data->rtcwkday = msgs->buf[1];
88 return 0;
89 }
90 if (regn >= MICROCHIP_MCP7940N_SRAM_OFFSET &&
91 regn + msgs->len - 1 <=
92 MICROCHIP_MCP7940N_SRAM_OFFSET + MICROCHIP_MCP7940N_SRAM_SIZE) {
93 for (int i = 0; i < msgs->len; ++i) {
94 data->data[regn + i - MICROCHIP_MCP7940N_SRAM_OFFSET] =
95 msgs->buf[1 + i];
96 }
97 return 0;
98 }
99 }
100
101 return -EIO;
102 }
103
104 static const struct i2c_emul_api mcp7940n_emul_api_i2c = {
105 .transfer = mcp7940n_emul_transfer_i2c,
106 };
107
mcp7940n_emul_backend_set_data(const struct emul * target,size_t offset,size_t count,const uint8_t * buffer)108 static int mcp7940n_emul_backend_set_data(const struct emul *target, size_t offset, size_t count,
109 const uint8_t *buffer)
110 {
111 struct mcp7940n_emul_data *data = target->data;
112
113 if (offset + count > MICROCHIP_MCP7940N_SRAM_SIZE) {
114 return -ERANGE;
115 }
116
117 for (size_t i = 0; i < count; ++i) {
118 data->data[offset + i] = buffer[i];
119 }
120 return 0;
121 }
122
mcp7940n_emul_backend_get_data(const struct emul * target,size_t offset,size_t count,uint8_t * buffer)123 static int mcp7940n_emul_backend_get_data(const struct emul *target, size_t offset, size_t count,
124 uint8_t *buffer)
125 {
126 struct mcp7940n_emul_data *data = target->data;
127
128 if (offset + count > MICROCHIP_MCP7940N_SRAM_SIZE) {
129 return -ERANGE;
130 }
131
132 for (size_t i = 0; i < count; ++i) {
133 buffer[i] = data->data[offset + i];
134 }
135 return 0;
136 }
137
138 static const struct emul_bbram_driver_api mcp7940n_emul_backend_api = {
139 .set_data = mcp7940n_emul_backend_set_data,
140 .get_data = mcp7940n_emul_backend_get_data,
141 };
142
143 #define MCP7940N_EMUL(inst) \
144 static const struct mcp7940n_emul_cfg mcp7940n_emul_cfg_##inst; \
145 static struct mcp7940n_emul_data mcp7940n_emul_data_##inst; \
146 EMUL_DT_INST_DEFINE(inst, mcp7940n_emul_init, &mcp7940n_emul_data_##inst, \
147 &mcp7940n_emul_cfg_##inst, &mcp7940n_emul_api_i2c, \
148 &mcp7940n_emul_backend_api)
149
150 DT_INST_FOREACH_STATUS_OKAY(MCP7940N_EMUL)
151
