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_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
  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
  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                 fallthrough;
 122
 123         case I2C_SLAVE_WRITE_REQUESTED:
 124                 memset(tu->regs, 0, TU_NUM_REGS);
 125                 tu->reg_idx = 0;
 126                 break;
 127
 128         case I2C_SLAVE_READ_PROCESSED:
 129                 if (is_proc_call && tu->regs[TU_REG_DATAH])
 130                         tu->regs[TU_REG_DATAH]--;
 131                 fallthrough;
 132
 133         case I2C_SLAVE_READ_REQUESTED:
 134                 *val = is_proc_call ? tu->regs[TU_REG_DATAH] : TU_CUR_VERSION;
 135                 break;
 136         }
 137
 138         return ret;
 139 }
 140
 141 static int i2c_slave_testunit_probe(struct i2c_client *client)
 142 {
 143         struct testunit_data *tu;
 144
 145         tu = devm_kzalloc(&client->dev, sizeof(struct testunit_data), GFP_KERNEL);
 146         if (!tu)
 147                 return -ENOMEM;
 148
 149         tu->client = client;
 150         i2c_set_clientdata(client, tu);
 151         INIT_DELAYED_WORK(&tu->worker, i2c_slave_testunit_work);
 152
 153         return i2c_slave_register(client, i2c_slave_testunit_slave_cb);
 154 };
 155
 156 static int i2c_slave_testunit_remove(struct i2c_client *client)
 157 {
 158         struct testunit_data *tu = i2c_get_clientdata(client);
 159
 160         cancel_delayed_work_sync(&tu->worker);
 161         i2c_slave_unregister(client);
 162         return 0;
 163 }
 164
 165 static const struct i2c_device_id i2c_slave_testunit_id[] = {
 166         { "slave-testunit", 0 },
 167         { }
 168 };
 169 MODULE_DEVICE_TABLE(i2c, i2c_slave_testunit_id);
 170
 171 static struct i2c_driver i2c_slave_testunit_driver = {
 172         .driver = {
 173                 .name = "i2c-slave-testunit",
 174         },
 175         .probe_new = i2c_slave_testunit_probe,
 176         .remove = i2c_slave_testunit_remove,
 177         .id_table = i2c_slave_testunit_id,
 178 };
 179 module_i2c_driver(i2c_slave_testunit_driver);
 180
 181 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
 182 MODULE_DESCRIPTION("I2C slave mode test unit");
 183 MODULE_LICENSE("GPL v2");