drivers/i2c/i2c-slave-testunit.c

   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_NUM_CMDS
  23 };
  24
  25 enum testunit_regs {
  26         TU_REG_CMD,
  27         TU_REG_DATAL,
  28         TU_REG_DATAH,
  29         TU_REG_DELAY,
  30         TU_NUM_REGS
  31 };
  32
  33 enum testunit_flags {
  34         TU_FLAG_IN_PROCESS,
  35 };
  36
  37 struct testunit_data {
  38         unsigned long flags;
  39         u8 regs[TU_NUM_REGS];
  40         u8 reg_idx;
  41         struct i2c_client *client;
  42         struct delayed_work worker;
  43 };
  44
  45 static void i2c_slave_testunit_work(struct work_struct *work)
  46 {
  47         struct testunit_data *tu = container_of(work, struct testunit_data, worker.work);
  48         struct i2c_msg msg;
  49         u8 msgbuf[256];
  50         int ret = 0;
  51
  52         msg.addr = I2C_CLIENT_END;
  53         msg.buf = msgbuf;
  54
  55         switch (tu->regs[TU_REG_CMD]) {
  56         case TU_CMD_READ_BYTES:
  57                 msg.addr = tu->regs[TU_REG_DATAL];
  58                 msg.flags = I2C_M_RD;
  59                 msg.len = tu->regs[TU_REG_DATAH];
  60                 break;
  61
  62         case TU_CMD_HOST_NOTIFY:
  63                 msg.addr = 0x08;
  64                 msg.flags = 0;
  65                 msg.len = 3;
  66                 msgbuf[0] = tu->client->addr;
  67                 msgbuf[1] = tu->regs[TU_REG_DATAL];
  68                 msgbuf[2] = tu->regs[TU_REG_DATAH];
  69                 break;
  70
  71         default:
  72                 break;
  73         }
  74
  75         if (msg.addr != I2C_CLIENT_END) {
  76                 ret = i2c_transfer(tu->client->adapter, &msg, 1);
  77                 /* convert '0 msgs transferred' to errno */
  78                 ret = (ret == 0) ? -EIO : ret;
  79         }
  80
  81         if (ret < 0)
  82                 dev_err(&tu->client->dev, "CMD%02X failed (%d)\n", tu->regs[TU_REG_CMD], ret);
  83
  84         clear_bit(TU_FLAG_IN_PROCESS, &tu->flags);
  85 }
  86
  87 static int i2c_slave_testunit_slave_cb(struct i2c_client *client,
  88                                      enum i2c_slave_event event, u8 *val)
  89 {
  90         struct testunit_data *tu = i2c_get_clientdata(client);
  91         int ret = 0;
  92
  93         switch (event) {
  94         case I2C_SLAVE_WRITE_RECEIVED:
  95                 if (test_bit(TU_FLAG_IN_PROCESS, &tu->flags))
  96                         return -EBUSY;
  97
  98                 if (tu->reg_idx < TU_NUM_REGS)
  99                         tu->regs[tu->reg_idx] = *val;
 100                 else
 101                         ret = -EMSGSIZE;
 102
 103                 if (tu->reg_idx <= TU_NUM_REGS)
 104                         tu->reg_idx++;
 105
 106                 /* TU_REG_CMD always written at this point */
 107                 if (tu->regs[TU_REG_CMD] >= TU_NUM_CMDS)
 108                         ret = -EINVAL;
 109
 110                 break;
 111
 112         case I2C_SLAVE_STOP:
 113                 if (tu->reg_idx == TU_NUM_REGS) {
 114                         set_bit(TU_FLAG_IN_PROCESS, &tu->flags);
 115                         queue_delayed_work(system_long_wq, &tu->worker,
 116                                            msecs_to_jiffies(10 * tu->regs[TU_REG_DELAY]));
 117                 }
 118                 fallthrough;
 119
 120         case I2C_SLAVE_WRITE_REQUESTED:
 121                 tu->reg_idx = 0;
 122                 break;
 123
 124         case I2C_SLAVE_READ_REQUESTED:
 125         case I2C_SLAVE_READ_PROCESSED:
 126                 *val = TU_CUR_VERSION;
 127                 break;
 128         }
 129
 130         return ret;
 131 }
 132
 133 static int i2c_slave_testunit_probe(struct i2c_client *client)
 134 {
 135         struct testunit_data *tu;
 136
 137         tu = devm_kzalloc(&client->dev, sizeof(struct testunit_data), GFP_KERNEL);
 138         if (!tu)
 139                 return -ENOMEM;
 140
 141         tu->client = client;
 142         i2c_set_clientdata(client, tu);
 143         INIT_DELAYED_WORK(&tu->worker, i2c_slave_testunit_work);
 144
 145         return i2c_slave_register(client, i2c_slave_testunit_slave_cb);
 146 };
 147
 148 static int i2c_slave_testunit_remove(struct i2c_client *client)
 149 {
 150         struct testunit_data *tu = i2c_get_clientdata(client);
 151
 152         cancel_delayed_work_sync(&tu->worker);
 153         i2c_slave_unregister(client);
 154         return 0;
 155 }
 156
 157 static const struct i2c_device_id i2c_slave_testunit_id[] = {
 158         { "slave-testunit", 0 },
 159         { }
 160 };
 161 MODULE_DEVICE_TABLE(i2c, i2c_slave_testunit_id);
 162
 163 static struct i2c_driver i2c_slave_testunit_driver = {
 164         .driver = {
 165                 .name = "i2c-slave-testunit",
 166         },
 167         .probe_new = i2c_slave_testunit_probe,
 168         .remove = i2c_slave_testunit_remove,
 169         .id_table = i2c_slave_testunit_id,
 170 };
 171 module_i2c_driver(i2c_slave_testunit_driver);
 172
 173 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
 174 MODULE_DESCRIPTION("I2C slave mode test unit");
 175 MODULE_LICENSE("GPL v2");