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// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2017 - 2018, Intel Corporation.
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/sysfs.h>
#define MQ_MSGBUF_SIZE CONFIG_I2C_SLAVE_MQUEUE_MESSAGE_SIZE
#define MQ_QUEUE_SIZE CONFIG_I2C_SLAVE_MQUEUE_QUEUE_SIZE
#define MQ_QUEUE_NEXT(x) (((x) + 1) & (MQ_QUEUE_SIZE - 1))
struct mq_msg {
int len;
u8 *buf;
};
struct mq_queue {
struct bin_attribute bin;
struct kernfs_node *kn;
struct i2c_client *client;
spinlock_t lock; /* spinlock for queue index handling */
int in;
int out;
struct mq_msg *curr;
int truncated; /* drop current if truncated */
struct mq_msg *queue;
};
static bool dump_debug __read_mostly;
static int dump_debug_bus_id __read_mostly;
#define I2C_HEX_DUMP(client, buf, len) \
do { \
if (dump_debug && \
(client)->adapter->nr == dump_debug_bus_id) { \
char dump_info[100] = {0,}; \
snprintf(dump_info, sizeof(dump_info), \
"bus_id:%d: ", (client)->adapter->nr); \
print_hex_dump(KERN_ERR, dump_info, DUMP_PREFIX_NONE, \
16, 1, buf, len, true); \
} \
} while (0)
static int i2c_slave_mqueue_callback(struct i2c_client *client,
enum i2c_slave_event event, u8 *val)
{
struct mq_queue *mq = i2c_get_clientdata(client);
struct mq_msg *msg = mq->curr;
int ret = 0;
switch (event) {
case I2C_SLAVE_WRITE_REQUESTED:
case I2C_SLAVE_GCALL_REQUESTED:
mq->truncated = 0;
msg->len = 1;
msg->buf[0] = event == I2C_SLAVE_GCALL_REQUESTED ?
0 : client->addr << 1;
break;
case I2C_SLAVE_WRITE_RECEIVED:
if (msg->len < MQ_MSGBUF_SIZE) {
msg->buf[msg->len++] = *val;
} else {
dev_err(&client->dev, "message is truncated!\n");
mq->truncated = 1;
ret = -EINVAL;
}
break;
case I2C_SLAVE_STOP:
if (unlikely(mq->truncated || msg->len < 2))
break;
spin_lock(&mq->lock);
mq->in = MQ_QUEUE_NEXT(mq->in);
mq->curr = &mq->queue[mq->in];
mq->curr->len = 0;
/* Flush the oldest message */
if (mq->out == mq->in)
mq->out = MQ_QUEUE_NEXT(mq->out);
spin_unlock(&mq->lock);
kernfs_notify(mq->kn);
break;
default:
*val = 0xFF;
break;
}
return ret;
}
static ssize_t i2c_slave_mqueue_bin_read(struct file *filp,
struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t pos, size_t count)
{
struct mq_queue *mq;
struct mq_msg *msg;
unsigned long flags;
bool more = false;
ssize_t ret = 0;
mq = dev_get_drvdata(container_of(kobj, struct device, kobj));
spin_lock_irqsave(&mq->lock, flags);
if (mq->out != mq->in) {
msg = &mq->queue[mq->out];
if (msg->len <= count) {
ret = msg->len;
memcpy(buf, msg->buf, ret);
I2C_HEX_DUMP(mq->client, buf, ret);
} else {
ret = -EOVERFLOW; /* Drop this HUGE one. */
}
mq->out = MQ_QUEUE_NEXT(mq->out);
if (mq->out != mq->in)
more = true;
}
spin_unlock_irqrestore(&mq->lock, flags);
if (more)
kernfs_notify(mq->kn);
return ret;
}
static int i2c_slave_mqueue_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct device *dev = &client->dev;
struct mq_queue *mq;
int ret, i;
void *buf;
mq = devm_kzalloc(dev, sizeof(*mq), GFP_KERNEL);
if (!mq)
return -ENOMEM;
BUILD_BUG_ON(!is_power_of_2(MQ_QUEUE_SIZE));
mq->client = client;
buf = devm_kmalloc_array(dev, MQ_QUEUE_SIZE, MQ_MSGBUF_SIZE,
GFP_KERNEL);
if (!buf)
return -ENOMEM;
mq->queue = devm_kzalloc(dev, sizeof(*mq->queue) * MQ_QUEUE_SIZE,
GFP_KERNEL);
if (!buf)
return -ENOMEM;
for (i = 0; i < MQ_QUEUE_SIZE; i++)
mq->queue[i].buf = buf + i * MQ_MSGBUF_SIZE;
i2c_set_clientdata(client, mq);
spin_lock_init(&mq->lock);
mq->curr = &mq->queue[0];
sysfs_bin_attr_init(&mq->bin);
mq->bin.attr.name = "slave-mqueue";
mq->bin.attr.mode = 0400;
mq->bin.read = i2c_slave_mqueue_bin_read;
mq->bin.size = MQ_MSGBUF_SIZE * MQ_QUEUE_SIZE;
ret = sysfs_create_bin_file(&dev->kobj, &mq->bin);
if (ret)
return ret;
mq->kn = kernfs_find_and_get(dev->kobj.sd, mq->bin.attr.name);
if (!mq->kn) {
sysfs_remove_bin_file(&dev->kobj, &mq->bin);
return -EFAULT;
}
ret = i2c_slave_register(client, i2c_slave_mqueue_callback);
if (ret) {
kernfs_put(mq->kn);
sysfs_remove_bin_file(&dev->kobj, &mq->bin);
return ret;
}
return 0;
}
static int i2c_slave_mqueue_remove(struct i2c_client *client)
{
struct mq_queue *mq = i2c_get_clientdata(client);
i2c_slave_unregister(client);
kernfs_put(mq->kn);
sysfs_remove_bin_file(&client->dev.kobj, &mq->bin);
return 0;
}
static const struct i2c_device_id i2c_slave_mqueue_id[] = {
{ "slave-mqueue", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, i2c_slave_mqueue_id);
#if IS_ENABLED(CONFIG_OF)
static const struct of_device_id i2c_slave_mqueue_of_match[] = {
{ .compatible = "slave-mqueue", .data = (void *)0 },
{ },
};
MODULE_DEVICE_TABLE(of, i2c_slave_mqueue_of_match);
#endif
static struct i2c_driver i2c_slave_mqueue_driver = {
.driver = {
.name = "i2c-slave-mqueue",
.of_match_table = of_match_ptr(i2c_slave_mqueue_of_match),
},
.probe = i2c_slave_mqueue_probe,
.remove = i2c_slave_mqueue_remove,
.id_table = i2c_slave_mqueue_id,
};
module_i2c_driver(i2c_slave_mqueue_driver);
module_param_named(dump_debug, dump_debug, bool, 0644);
MODULE_PARM_DESC(dump_debug, "debug flag for dump printing");
module_param_named(dump_debug_bus_id, dump_debug_bus_id, int, 0644);
MODULE_PARM_DESC(dump_debug_bus_id, "bus id for dump debug printing");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Haiyue Wang <haiyue.wang@linux.intel.com>");
MODULE_DESCRIPTION("I2C slave mode for receiving and queuing messages");
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