1 /*
2 * Copyright 2020 Google LLC
3 * Copyright (c) 2020 Nordic Semiconductor ASA
4 *
5 * SPDX-License-Identifier: Apache-2.0
6 */
7
8 #define DT_DRV_COMPAT atmel_at24
9
10 #define LOG_LEVEL CONFIG_I2C_LOG_LEVEL
11 #include <logging/log.h>
12 LOG_MODULE_REGISTER(atmel_at24);
13
14 #include <device.h>
15 #include <drivers/emul.h>
16 #include <drivers/i2c.h>
17 #include <drivers/i2c_emul.h>
18
19 /** Run-time data used by the emulator */
20 struct at24_emul_data {
21 /** I2C emulator detail */
22 struct i2c_emul emul;
23 /** AT24 device being emulated */
24 const struct device *i2c;
25 /** Configuration information */
26 const struct at24_emul_cfg *cfg;
27 /** Current register to read (address) */
28 uint32_t cur_reg;
29 };
30
31 /** Static configuration for the emulator */
32 struct at24_emul_cfg {
33 /** Label of the I2C bus this emulator connects to */
34 const char *i2c_label;
35 /** Pointer to run-time data */
36 struct at24_emul_data *data;
37 /** EEPROM data contents */
38 uint8_t *buf;
39 /** Size of EEPROM in bytes */
40 uint32_t size;
41 /** Address of EEPROM on i2c bus */
42 uint16_t addr;
43 /** Address width for EEPROM in bits (only 8 is supported at present) */
44 uint8_t addr_width;
45 };
46
47 /**
48 * Emulator an I2C transfer to an AT24 chip
49 *
50 * This handles simple reads and writes
51 *
52 * @param emul I2C emulation information
53 * @param msgs List of messages to process. For 'read' messages, this function
54 * updates the 'buf' member with the data that was read
55 * @param num_msgs Number of messages to process
56 * @param addr Address of the I2C target device. This is assumed to be correct,
57 * due to the
58 * @retval 0 If successful
59 * @retval -EIO General input / output error
60 */
at24_emul_transfer(struct i2c_emul * emul,struct i2c_msg * msgs,int num_msgs,int addr)61 static int at24_emul_transfer(struct i2c_emul *emul, struct i2c_msg *msgs,
62 int num_msgs, int addr)
63 {
64 struct at24_emul_data *data;
65 const struct at24_emul_cfg *cfg;
66 unsigned int len;
67 bool too_fast;
68
69 data = CONTAINER_OF(emul, struct at24_emul_data, emul);
70 cfg = data->cfg;
71
72 if (cfg->addr != addr) {
73 LOG_ERR("Address mismatch, expected %02x, got %02x", cfg->addr,
74 addr);
75 return -EIO;
76 }
77
78 /* For testing purposes, fail if the bus speed is above standard */
79 too_fast = (I2C_SPEED_GET(i2c_emul_get_config(data->i2c)) >
80 I2C_SPEED_STANDARD);
81 if (too_fast) {
82 LOG_ERR("Speed too high");
83 return -EIO;
84 }
85
86 i2c_dump_msgs("emul", msgs, num_msgs, addr);
87 switch (num_msgs) {
88 case 1:
89 if (msgs->flags & I2C_MSG_READ) {
90 /* handle read */
91 break;
92 }
93 data->cur_reg = msgs->buf[0];
94 len = MIN(msgs->len - 1, cfg->size - data->cur_reg);
95 memcpy(&cfg->buf[data->cur_reg], &msgs->buf[1], len);
96 return 0;
97 case 2:
98 if (msgs->flags & I2C_MSG_READ) {
99 LOG_ERR("Unexpected read");
100 return -EIO;
101 }
102 data->cur_reg = msgs->buf[0];
103
104 /* Now process the 'read' part of the message */
105 msgs++;
106 if (!(msgs->flags & I2C_MSG_READ)) {
107 LOG_ERR("Unexpected write");
108 return -EIO;
109 }
110 break;
111 default:
112 LOG_ERR("Invalid number of messages");
113 return -EIO;
114 }
115
116 /* Read data from the EEPROM into the buffer */
117 len = MIN(msgs->len, cfg->size - data->cur_reg);
118 memcpy(msgs->buf, &cfg->buf[data->cur_reg], len);
119 data->cur_reg += len;
120
121 return 0;
122 }
123
124 /* Device instantiation */
125
126 static struct i2c_emul_api at24_emul_api = {
127 .transfer = at24_emul_transfer,
128 };
129
130 /**
131 * Set up a new AT24 emulator
132 *
133 * This should be called for each AT24 device that needs to be emulated. It
134 * registers it with the I2C emulation controller.
135 *
136 * @param emul Emulation information
137 * @param parent Device to emulate (must use AT24 driver)
138 * @return 0 indicating success (always)
139 */
emul_atmel_at24_init(const struct emul * emul,const struct device * parent)140 static int emul_atmel_at24_init(const struct emul *emul,
141 const struct device *parent)
142 {
143 const struct at24_emul_cfg *cfg = emul->cfg;
144 struct at24_emul_data *data = cfg->data;
145
146 data->emul.api = &at24_emul_api;
147 data->emul.addr = cfg->addr;
148 data->i2c = parent;
149 data->cfg = cfg;
150 data->cur_reg = 0;
151
152 /* Start with an erased EEPROM, assuming all 0xff */
153 memset(cfg->buf, 0xff, cfg->size);
154
155 int rc = i2c_emul_register(parent, emul->dev_label, &data->emul);
156
157 return rc;
158 }
159
160 #define EEPROM_AT24_EMUL(n) \
161 static uint8_t at24_emul_buf_##n[DT_INST_PROP(n, size)]; \
162 static struct at24_emul_data at24_emul_data_##n; \
163 static const struct at24_emul_cfg at24_emul_cfg_##n = { \
164 .i2c_label = DT_INST_BUS_LABEL(n), \
165 .data = &at24_emul_data_##n, \
166 .buf = at24_emul_buf_##n, \
167 .size = DT_INST_PROP(n, size), \
168 .addr = DT_INST_REG_ADDR(n), \
169 .addr_width = 8, \
170 }; \
171 EMUL_DEFINE(emul_atmel_at24_init, DT_DRV_INST(n), &at24_emul_cfg_##n)
172
173 DT_INST_FOREACH_STATUS_OKAY(EEPROM_AT24_EMUL)
174
