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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* tsi-core.c - file defining SB-TSI protocols compliant
* AMD SoC device.
*
* Copyright (C) 2026 Advanced Micro Devices, Inc.
*/
#include <linux/fs.h>
#include <linux/ioctl.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <uapi/misc/amd-apml.h>
#include "tsi-core.h"
static inline struct sbtsi_i3c_priv *to_sbtsi_i3c_priv(struct sbtsi_data *data)
{
return container_of(data, struct sbtsi_i3c_priv, data);
}
void sbtsi_data_release(struct kref *kref)
{
struct sbtsi_data *data = container_of(kref, struct sbtsi_data, kref);
mutex_destroy(&data->lock);
if (data->is_i3c)
kfree(to_sbtsi_i3c_priv(data));
else
kfree(data);
}
/* I2C transfer function */
static int sbtsi_i2c_xfer(struct sbtsi_data *data, u8 reg, u8 *val, bool is_read)
{
if (is_read) {
int ret = i2c_smbus_read_byte_data(data->client, reg);
if (ret < 0)
return ret;
*val = ret;
return 0;
}
return i2c_smbus_write_byte_data(data->client, reg, *val);
}
/* I3C read transfer function */
static int sbtsi_i3c_read(struct sbtsi_data *data, u8 reg, u8 *val)
{
struct sbtsi_i3c_priv *priv = to_sbtsi_i3c_priv(data);
struct i3c_xfer xfers[2] = { };
int ret;
priv->tx[0] = reg;
/* Write the register address (DMA_TO_DEVICE). */
xfers[0].rnw = false;
xfers[0].len = 1;
xfers[0].data.out = priv->tx;
/* Read the data byte into a separate buffer (DMA_FROM_DEVICE). */
xfers[1].rnw = true;
xfers[1].len = 1;
xfers[1].data.in = &priv->rx;
ret = i3c_device_do_xfers(data->i3cdev, xfers, 2, I3C_SDR);
if (ret)
return ret;
*val = priv->rx;
return ret;
}
/* I3C write transfer function */
static int sbtsi_i3c_write(struct sbtsi_data *data, u8 reg, u8 val)
{
struct sbtsi_i3c_priv *priv = to_sbtsi_i3c_priv(data);
struct i3c_xfer xfers = {
.rnw = false,
.len = 2,
.data.out = priv->tx,
};
priv->tx[0] = reg;
priv->tx[1] = val;
return i3c_device_do_xfers(data->i3cdev, &xfers, 1, I3C_SDR);
}
/* Unified transfer function for I2C and I3C access */
int sbtsi_xfer(struct sbtsi_data *data, u8 reg, u8 *val, bool is_read)
{
if (data->is_i3c)
return is_read ? sbtsi_i3c_read(data, reg, val)
: sbtsi_i3c_write(data, reg, *val);
return sbtsi_i2c_xfer(data, reg, val, is_read);
}
EXPORT_SYMBOL_GPL(sbtsi_xfer);
/*
* The mutex protects against concurrent register transfers to the device
* over the shared bus.
*/
static int sbtsi_xfer_ioctl(struct sbtsi_data *data, u8 reg, u8 *val, bool is_read)
{
guard(sbtsi)(data);
if (data->detached)
return -ENODEV;
return sbtsi_xfer(data, reg, val, is_read);
}
static int apml_tsi_reg_xfer(struct sbtsi_data *data,
struct apml_tsi_xfer_msg __user *arg)
{
struct apml_tsi_xfer_msg msg = { 0 };
int ret;
if (copy_from_user(&msg, arg, sizeof(struct apml_tsi_xfer_msg)))
return -EFAULT;
/*
* rflag is a boolean direction flag (0 = write, 1 = read). Reject
* any other value so the upper values stay reserved for future
* extensions instead of being silently treated as a read.
*/
if (msg.pad || msg.rflag > 1)
return -EINVAL;
ret = sbtsi_xfer_ioctl(data, msg.reg_addr, &msg.data_in_out, msg.rflag);
if (msg.rflag && !ret) {
if (copy_to_user(arg, &msg, sizeof(struct apml_tsi_xfer_msg)))
return -EFAULT;
}
return ret;
}
static int sbtsi_open(struct inode *inode, struct file *fp)
{
struct sbtsi_data *data;
data = container_of(fp->private_data, struct sbtsi_data, sbtsi_misc_dev);
scoped_guard(sbtsi, data) {
if (data->detached)
return -ENODEV;
}
kref_get(&data->kref);
return 0;
}
static int sbtsi_release(struct inode *inode, struct file *fp)
{
struct sbtsi_data *data;
data = container_of(fp->private_data, struct sbtsi_data, sbtsi_misc_dev);
kref_put(&data->kref, sbtsi_data_release);
return 0;
}
static long sbtsi_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
{
void __user *argp = (void __user *)arg;
struct sbtsi_data *data;
data = container_of(fp->private_data, struct sbtsi_data, sbtsi_misc_dev);
switch (cmd) {
case SBTSI_IOCTL_REG_XFER_CMD:
return apml_tsi_reg_xfer(data, argp);
default:
return -ENOTTY;
}
}
static const struct file_operations sbtsi_fops = {
.owner = THIS_MODULE,
.open = sbtsi_open,
.release = sbtsi_release,
.unlocked_ioctl = sbtsi_ioctl,
.compat_ioctl = compat_ptr_ioctl,
};
int create_misc_tsi_device(struct sbtsi_data *data, struct device *dev)
{
int ret;
data->sbtsi_misc_dev.name = devm_kasprintf(dev, GFP_KERNEL,
"sbtsi-%x", data->dev_addr);
if (!data->sbtsi_misc_dev.name)
return -ENOMEM;
data->sbtsi_misc_dev.minor = MISC_DYNAMIC_MINOR;
data->sbtsi_misc_dev.fops = &sbtsi_fops;
data->sbtsi_misc_dev.parent = dev;
data->sbtsi_misc_dev.nodename = devm_kasprintf(dev, GFP_KERNEL,
"sbtsi-%x", data->dev_addr);
if (!data->sbtsi_misc_dev.nodename)
return -ENOMEM;
data->sbtsi_misc_dev.mode = 0600;
ret = misc_register(&data->sbtsi_misc_dev);
if (ret)
return ret;
return 0;
}
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