1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * I2C slave mode testunit
4 *
5 * Copyright (C) 2020 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
6 * Copyright (C) 2020 by Renesas Electronics Corporation
7 */
8
9 #include <linux/bitops.h>
10 #include <linux/i2c.h>
11 #include <linux/init.h>
12 #include <linux/module.h>
13 #include <linux/of.h>
14 #include <linux/slab.h>
15 #include <linux/workqueue.h> /* FIXME: is system_long_wq the best choice? */
16
17 #define TU_CUR_VERSION 0x01
18
19 enum testunit_cmds {
20 TU_CMD_READ_BYTES = 1, /* save 0 for ABORT, RESET or similar */
21 TU_CMD_HOST_NOTIFY,
22 TU_CMD_SMBUS_BLOCK_PROC_CALL,
23 TU_NUM_CMDS
24 };
25
26 enum testunit_regs {
27 TU_REG_CMD,
28 TU_REG_DATAL,
29 TU_REG_DATAH,
30 TU_REG_DELAY,
31 TU_NUM_REGS
32 };
33
34 enum testunit_flags {
35 TU_FLAG_IN_PROCESS,
36 };
37
38 struct testunit_data {
39 unsigned long flags;
40 u8 regs[TU_NUM_REGS];
41 u8 reg_idx;
42 struct i2c_client *client;
43 struct delayed_work worker;
44 };
45
i2c_slave_testunit_work(struct work_struct * work)46 static void i2c_slave_testunit_work(struct work_struct *work)
47 {
48 struct testunit_data *tu = container_of(work, struct testunit_data, worker.work);
49 struct i2c_msg msg;
50 u8 msgbuf[256];
51 int ret = 0;
52
53 msg.addr = I2C_CLIENT_END;
54 msg.buf = msgbuf;
55
56 switch (tu->regs[TU_REG_CMD]) {
57 case TU_CMD_READ_BYTES:
58 msg.addr = tu->regs[TU_REG_DATAL];
59 msg.flags = I2C_M_RD;
60 msg.len = tu->regs[TU_REG_DATAH];
61 break;
62
63 case TU_CMD_HOST_NOTIFY:
64 msg.addr = 0x08;
65 msg.flags = 0;
66 msg.len = 3;
67 msgbuf[0] = tu->client->addr;
68 msgbuf[1] = tu->regs[TU_REG_DATAL];
69 msgbuf[2] = tu->regs[TU_REG_DATAH];
70 break;
71
72 default:
73 break;
74 }
75
76 if (msg.addr != I2C_CLIENT_END) {
77 ret = i2c_transfer(tu->client->adapter, &msg, 1);
78 /* convert '0 msgs transferred' to errno */
79 ret = (ret == 0) ? -EIO : ret;
80 }
81
82 if (ret < 0)
83 dev_err(&tu->client->dev, "CMD%02X failed (%d)\n", tu->regs[TU_REG_CMD], ret);
84
85 clear_bit(TU_FLAG_IN_PROCESS, &tu->flags);
86 }
87
i2c_slave_testunit_slave_cb(struct i2c_client * client,enum i2c_slave_event event,u8 * val)88 static int i2c_slave_testunit_slave_cb(struct i2c_client *client,
89 enum i2c_slave_event event, u8 *val)
90 {
91 struct testunit_data *tu = i2c_get_clientdata(client);
92 bool is_proc_call = tu->reg_idx == 3 && tu->regs[TU_REG_DATAL] == 1 &&
93 tu->regs[TU_REG_CMD] == TU_CMD_SMBUS_BLOCK_PROC_CALL;
94 int ret = 0;
95
96 switch (event) {
97 case I2C_SLAVE_WRITE_RECEIVED:
98 if (test_bit(TU_FLAG_IN_PROCESS, &tu->flags))
99 return -EBUSY;
100
101 if (tu->reg_idx < TU_NUM_REGS)
102 tu->regs[tu->reg_idx] = *val;
103 else
104 ret = -EMSGSIZE;
105
106 if (tu->reg_idx <= TU_NUM_REGS)
107 tu->reg_idx++;
108
109 /* TU_REG_CMD always written at this point */
110 if (tu->regs[TU_REG_CMD] >= TU_NUM_CMDS)
111 ret = -EINVAL;
112
113 break;
114
115 case I2C_SLAVE_STOP:
116 if (tu->reg_idx == TU_NUM_REGS) {
117 set_bit(TU_FLAG_IN_PROCESS, &tu->flags);
118 queue_delayed_work(system_long_wq, &tu->worker,
119 msecs_to_jiffies(10 * tu->regs[TU_REG_DELAY]));
120 }
121
122 /*
123 * Reset reg_idx to avoid that work gets queued again in case of
124 * STOP after a following read message. But do not clear TU regs
125 * here because we still need them in the workqueue!
126 */
127 tu->reg_idx = 0;
128 break;
129
130 case I2C_SLAVE_WRITE_REQUESTED:
131 if (test_bit(TU_FLAG_IN_PROCESS, &tu->flags))
132 return -EBUSY;
133
134 memset(tu->regs, 0, TU_NUM_REGS);
135 tu->reg_idx = 0;
136 break;
137
138 case I2C_SLAVE_READ_PROCESSED:
139 if (is_proc_call && tu->regs[TU_REG_DATAH])
140 tu->regs[TU_REG_DATAH]--;
141 fallthrough;
142
143 case I2C_SLAVE_READ_REQUESTED:
144 *val = is_proc_call ? tu->regs[TU_REG_DATAH] : TU_CUR_VERSION;
145 break;
146 }
147
148 return ret;
149 }
150
i2c_slave_testunit_probe(struct i2c_client * client)151 static int i2c_slave_testunit_probe(struct i2c_client *client)
152 {
153 struct testunit_data *tu;
154
155 tu = devm_kzalloc(&client->dev, sizeof(struct testunit_data), GFP_KERNEL);
156 if (!tu)
157 return -ENOMEM;
158
159 tu->client = client;
160 i2c_set_clientdata(client, tu);
161 INIT_DELAYED_WORK(&tu->worker, i2c_slave_testunit_work);
162
163 return i2c_slave_register(client, i2c_slave_testunit_slave_cb);
164 };
165
i2c_slave_testunit_remove(struct i2c_client * client)166 static void i2c_slave_testunit_remove(struct i2c_client *client)
167 {
168 struct testunit_data *tu = i2c_get_clientdata(client);
169
170 cancel_delayed_work_sync(&tu->worker);
171 i2c_slave_unregister(client);
172 }
173
174 static const struct i2c_device_id i2c_slave_testunit_id[] = {
175 { "slave-testunit", 0 },
176 { }
177 };
178 MODULE_DEVICE_TABLE(i2c, i2c_slave_testunit_id);
179
180 static struct i2c_driver i2c_slave_testunit_driver = {
181 .driver = {
182 .name = "i2c-slave-testunit",
183 },
184 .probe = i2c_slave_testunit_probe,
185 .remove = i2c_slave_testunit_remove,
186 .id_table = i2c_slave_testunit_id,
187 };
188 module_i2c_driver(i2c_slave_testunit_driver);
189
190 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
191 MODULE_DESCRIPTION("I2C slave mode test unit");
192 MODULE_LICENSE("GPL v2");
193