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// SPDX-License-Identifier: GPL-2.0-only
/*
* I2C slave mode testunit
*
* Copyright (C) 2020 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
* Copyright (C) 2020 by Renesas Electronics Corporation
*/
#include <generated/utsrelease.h>
#include <linux/bitops.h>
#include <linux/completion.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/workqueue.h> /* FIXME: is system_long_wq the best choice? */
#define TU_VERSION_MAX_LENGTH 128
enum testunit_cmds {
TU_CMD_READ_BYTES = 1, /* save 0 for ABORT, RESET or similar */
TU_CMD_SMBUS_HOST_NOTIFY,
TU_CMD_SMBUS_BLOCK_PROC_CALL,
TU_CMD_GET_VERSION_WITH_REP_START,
TU_CMD_SMBUS_ALERT_REQUEST,
TU_NUM_CMDS
};
enum testunit_regs {
TU_REG_CMD,
TU_REG_DATAL,
TU_REG_DATAH,
TU_REG_DELAY,
TU_NUM_REGS
};
enum testunit_flags {
TU_FLAG_IN_PROCESS,
};
struct testunit_data {
unsigned long flags;
u8 regs[TU_NUM_REGS];
u8 reg_idx;
u8 read_idx;
struct i2c_client *client;
struct delayed_work worker;
struct gpio_desc *gpio;
struct completion alert_done;
};
static char tu_version_info[] = "v" UTS_RELEASE "\n\0";
static int i2c_slave_testunit_smbalert_cb(struct i2c_client *client,
enum i2c_slave_event event, u8 *val)
{
struct testunit_data *tu = i2c_get_clientdata(client);
switch (event) {
case I2C_SLAVE_READ_PROCESSED:
gpiod_set_value(tu->gpio, 0);
fallthrough;
case I2C_SLAVE_READ_REQUESTED:
*val = tu->regs[TU_REG_DATAL];
break;
case I2C_SLAVE_STOP:
complete(&tu->alert_done);
break;
case I2C_SLAVE_WRITE_REQUESTED:
case I2C_SLAVE_WRITE_RECEIVED:
return -EOPNOTSUPP;
}
return 0;
}
static int i2c_slave_testunit_slave_cb(struct i2c_client *client,
enum i2c_slave_event event, u8 *val)
{
struct testunit_data *tu = i2c_get_clientdata(client);
bool is_proc_call = tu->reg_idx == 3 && tu->regs[TU_REG_DATAL] == 1 &&
tu->regs[TU_REG_CMD] == TU_CMD_SMBUS_BLOCK_PROC_CALL;
bool is_get_version = tu->reg_idx == 3 &&
tu->regs[TU_REG_CMD] == TU_CMD_GET_VERSION_WITH_REP_START;
int ret = 0;
switch (event) {
case I2C_SLAVE_WRITE_REQUESTED:
if (test_bit(TU_FLAG_IN_PROCESS, &tu->flags))
return -EBUSY;
memset(tu->regs, 0, TU_NUM_REGS);
tu->reg_idx = 0;
tu->read_idx = 0;
break;
case I2C_SLAVE_WRITE_RECEIVED:
if (test_bit(TU_FLAG_IN_PROCESS, &tu->flags))
return -EBUSY;
if (tu->reg_idx < TU_NUM_REGS)
tu->regs[tu->reg_idx] = *val;
else
ret = -EMSGSIZE;
if (tu->reg_idx <= TU_NUM_REGS)
tu->reg_idx++;
/* TU_REG_CMD always written at this point */
if (tu->regs[TU_REG_CMD] >= TU_NUM_CMDS)
ret = -EINVAL;
break;
case I2C_SLAVE_STOP:
if (tu->reg_idx == TU_NUM_REGS) {
set_bit(TU_FLAG_IN_PROCESS, &tu->flags);
queue_delayed_work(system_long_wq, &tu->worker,
msecs_to_jiffies(10 * tu->regs[TU_REG_DELAY]));
}
/*
* Reset reg_idx to avoid that work gets queued again in case of
* STOP after a following read message. But do not clear TU regs
* here because we still need them in the workqueue!
*/
tu->reg_idx = 0;
break;
case I2C_SLAVE_READ_PROCESSED:
/* Advance until we reach the NUL character */
if (is_get_version && tu_version_info[tu->read_idx] != 0)
tu->read_idx++;
else if (is_proc_call && tu->regs[TU_REG_DATAH])
tu->regs[TU_REG_DATAH]--;
fallthrough;
case I2C_SLAVE_READ_REQUESTED:
if (is_get_version)
*val = tu_version_info[tu->read_idx];
else if (is_proc_call)
*val = tu->regs[TU_REG_DATAH];
else
*val = test_bit(TU_FLAG_IN_PROCESS, &tu->flags) ?
tu->regs[TU_REG_CMD] : 0;
break;
}
return ret;
}
static void i2c_slave_testunit_work(struct work_struct *work)
{
struct testunit_data *tu = container_of(work, struct testunit_data, worker.work);
unsigned long time_left;
struct i2c_msg msg;
u8 msgbuf[256];
u16 orig_addr;
int ret = 0;
msg.addr = I2C_CLIENT_END;
msg.buf = msgbuf;
switch (tu->regs[TU_REG_CMD]) {
case TU_CMD_READ_BYTES:
msg.addr = tu->regs[TU_REG_DATAL];
msg.flags = I2C_M_RD;
msg.len = tu->regs[TU_REG_DATAH];
break;
case TU_CMD_SMBUS_HOST_NOTIFY:
msg.addr = 0x08;
msg.flags = 0;
msg.len = 3;
msgbuf[0] = tu->client->addr;
msgbuf[1] = tu->regs[TU_REG_DATAL];
msgbuf[2] = tu->regs[TU_REG_DATAH];
break;
case TU_CMD_SMBUS_ALERT_REQUEST:
if (!tu->gpio) {
ret = -ENOENT;
break;
}
i2c_slave_unregister(tu->client);
orig_addr = tu->client->addr;
tu->client->addr = 0x0c;
ret = i2c_slave_register(tu->client, i2c_slave_testunit_smbalert_cb);
if (ret)
goto out_smbalert;
reinit_completion(&tu->alert_done);
gpiod_set_value(tu->gpio, 1);
time_left = wait_for_completion_timeout(&tu->alert_done, HZ);
if (!time_left)
ret = -ETIMEDOUT;
i2c_slave_unregister(tu->client);
out_smbalert:
tu->client->addr = orig_addr;
i2c_slave_register(tu->client, i2c_slave_testunit_slave_cb);
break;
default:
break;
}
if (msg.addr != I2C_CLIENT_END) {
ret = i2c_transfer(tu->client->adapter, &msg, 1);
/* convert '0 msgs transferred' to errno */
ret = (ret == 0) ? -EIO : ret;
}
if (ret < 0)
dev_err(&tu->client->dev, "CMD%02X failed (%d)\n", tu->regs[TU_REG_CMD], ret);
clear_bit(TU_FLAG_IN_PROCESS, &tu->flags);
}
static int i2c_slave_testunit_probe(struct i2c_client *client)
{
struct testunit_data *tu;
tu = devm_kzalloc(&client->dev, sizeof(struct testunit_data), GFP_KERNEL);
if (!tu)
return -ENOMEM;
tu->client = client;
i2c_set_clientdata(client, tu);
init_completion(&tu->alert_done);
INIT_DELAYED_WORK(&tu->worker, i2c_slave_testunit_work);
tu->gpio = devm_gpiod_get_index_optional(&client->dev, NULL, 0, GPIOD_OUT_LOW);
if (IS_ERR(tu->gpio))
return PTR_ERR(tu->gpio);
if (gpiod_cansleep(tu->gpio)) {
dev_err(&client->dev, "GPIO access which may sleep is not allowed\n");
return -EDEADLK;
}
if (sizeof(tu_version_info) > TU_VERSION_MAX_LENGTH)
tu_version_info[TU_VERSION_MAX_LENGTH - 1] = 0;
return i2c_slave_register(client, i2c_slave_testunit_slave_cb);
};
static void i2c_slave_testunit_remove(struct i2c_client *client)
{
struct testunit_data *tu = i2c_get_clientdata(client);
cancel_delayed_work_sync(&tu->worker);
i2c_slave_unregister(client);
}
static const struct i2c_device_id i2c_slave_testunit_id[] = {
{ "slave-testunit" },
{ }
};
MODULE_DEVICE_TABLE(i2c, i2c_slave_testunit_id);
static struct i2c_driver i2c_slave_testunit_driver = {
.driver = {
.name = "i2c-slave-testunit",
},
.probe = i2c_slave_testunit_probe,
.remove = i2c_slave_testunit_remove,
.id_table = i2c_slave_testunit_id,
};
module_i2c_driver(i2c_slave_testunit_driver);
MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
MODULE_DESCRIPTION("I2C slave mode test unit");
MODULE_LICENSE("GPL v2");
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