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Subject[RFC v2 4/4] i3c: add i3cdev module to expose i3c dev in /dev
Date
This patch adds user mode support to I3C SDR transfers.

The module is based on i2c-dev.c with the follow features:
- expose on /dev the i3c devices dynamically based on if they have
a device driver bound.
- Dynamically allocate the char device Major number.

Signed-off-by: Vitor Soares <vitor.soares@synopsys.com>
---
drivers/i3c/Kconfig | 15 ++
drivers/i3c/Makefile | 1 +
drivers/i3c/i3cdev.c | 429 ++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/i3c/i3cdev.h | 38 ++++
4 files changed, 483 insertions(+)
create mode 100644 drivers/i3c/i3cdev.c
create mode 100644 include/uapi/linux/i3c/i3cdev.h

diff --git a/drivers/i3c/Kconfig b/drivers/i3c/Kconfig
index 30a4415..0164276 100644
--- a/drivers/i3c/Kconfig
+++ b/drivers/i3c/Kconfig
@@ -20,5 +20,20 @@ menuconfig I3C
will be called i3c.

if I3C
+
+config I3CDEV
+ tristate "I3C device interface"
+ depends on I3C
+ help
+ Say Y here to use i3c-* device files, usually found in the /dev
+ directory on your system. They make it possible to have user-space
+ programs use the I3C devices.
+
+ This support is also available as a module. If so, the module
+ will be called i3cdev.
+
+ Note that this application programming interface is EXPERIMENTAL
+ and hence SUBJECT TO CHANGE WITHOUT NOTICE while it stabilizes.
+
source "drivers/i3c/master/Kconfig"
endif # I3C
diff --git a/drivers/i3c/Makefile b/drivers/i3c/Makefile
index 11982ef..606d422 100644
--- a/drivers/i3c/Makefile
+++ b/drivers/i3c/Makefile
@@ -1,4 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
i3c-y := device.o master.o
obj-$(CONFIG_I3C) += i3c.o
+obj-$(CONFIG_I3CDEV) += i3cdev.o
obj-$(CONFIG_I3C) += master/
diff --git a/drivers/i3c/i3cdev.c b/drivers/i3c/i3cdev.c
new file mode 100644
index 0000000..f1140dc
--- /dev/null
+++ b/drivers/i3c/i3cdev.c
@@ -0,0 +1,429 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 Synopsys, Inc. and/or its affiliates.
+ *
+ * Author: Vitor Soares <soares@synopsys.com>
+ */
+
+#include <linux/cdev.h>
+#include <linux/compat.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+
+#include <linux/i3c/i3cdev.h>
+
+#include "internals.h"
+
+struct i3cdev_data {
+ struct list_head list;
+ struct i3c_device *i3c;
+ struct cdev cdev;
+ struct device *dev;
+ int id;
+};
+
+static DEFINE_IDA(i3cdev_ida);
+static dev_t i3cdev_number;
+#define I3C_MINORS 16 /* 16 I3C devices supported for now */
+
+static LIST_HEAD(i3cdev_list);
+static DEFINE_SPINLOCK(i3cdev_list_lock);
+
+static struct i3cdev_data *i3cdev_get_by_i3c(struct i3c_device *i3c)
+{
+ struct i3cdev_data *i3cdev;
+
+ spin_lock(&i3cdev_list_lock);
+ list_for_each_entry(i3cdev, &i3cdev_list, list) {
+ if (i3cdev->i3c == i3c)
+ goto found;
+ }
+
+ i3cdev = NULL;
+
+found:
+ spin_unlock(&i3cdev_list_lock);
+ return i3cdev;
+}
+
+static struct i3cdev_data *get_free_i3cdev(struct i3c_device *i3c)
+{
+ struct i3cdev_data *i3cdev;
+ int id;
+
+ id = ida_simple_get(&i3cdev_ida, 0, I3C_MINORS, GFP_KERNEL);
+ if (id < 0) {
+ pr_err("i3cdev: no minor number available!\n");
+ return ERR_PTR(id);
+ }
+
+ i3cdev = kzalloc(sizeof(*i3cdev), GFP_KERNEL);
+ if (!i3cdev) {
+ ida_simple_remove(&i3cdev_ida, id);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ i3cdev->i3c = i3c;
+ i3cdev->id = id;
+
+ spin_lock(&i3cdev_list_lock);
+ list_add_tail(&i3cdev->list, &i3cdev_list);
+ spin_unlock(&i3cdev_list_lock);
+
+ return i3cdev;
+}
+
+static void put_i3cdev(struct i3cdev_data *i3cdev)
+{
+ spin_lock(&i3cdev_list_lock);
+ list_del(&i3cdev->list);
+ spin_unlock(&i3cdev_list_lock);
+ kfree(i3cdev);
+}
+
+static ssize_t
+i3cdev_read(struct file *file, char __user *buf, size_t count, loff_t *f_pos)
+{
+ struct i3c_device *i3c = file->private_data;
+ struct i3c_priv_xfer xfers = {
+ .rnw = true,
+ .len = count,
+ };
+ char *tmp;
+ int ret;
+
+ tmp = kzalloc(count, GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;
+
+ xfers.data.in = tmp;
+
+ dev_dbg(&i3c->dev, "Reading %zu bytes.\n", count);
+
+ ret = i3c_device_do_priv_xfers(i3c, &xfers, 1);
+ if (!ret)
+ ret = copy_to_user(buf, tmp, count) ? -EFAULT : ret;
+
+ kfree(tmp);
+ return ret;
+}
+
+static ssize_t
+i3cdev_write(struct file *file, const char __user *buf, size_t count,
+ loff_t *f_pos)
+{
+ struct i3c_device *i3c = file->private_data;
+ struct i3c_priv_xfer xfers = {
+ .rnw = false,
+ .len = count,
+ };
+ char *tmp;
+ int ret;
+
+ tmp = memdup_user(buf, count);
+ if (IS_ERR(tmp))
+ return PTR_ERR(tmp);
+
+ xfers.data.out = tmp;
+
+ dev_dbg(&i3c->dev, "Writing %zu bytes.\n", count);
+
+ ret = i3c_device_do_priv_xfers(i3c, &xfers, 1);
+ kfree(tmp);
+ return (!ret) ? count : ret;
+}
+
+static int
+i3cdev_do_priv_xfer(struct i3c_device *dev, struct i3c_ioc_priv_xfer *xfers,
+ unsigned int nxfers)
+{
+ struct i3c_priv_xfer *k_xfers;
+ u8 **data_ptrs;
+ int i, ret = 0;
+
+ k_xfers = kcalloc(nxfers, sizeof(*k_xfers), GFP_KERNEL);
+ if (!k_xfers)
+ return -ENOMEM;
+
+ data_ptrs = kcalloc(nxfers, sizeof(*data_ptrs), GFP_KERNEL);
+ if (!data_ptrs) {
+ ret = -ENOMEM;
+ goto err_free_k_xfer;
+ }
+
+ for (i = 0; i < nxfers; i++) {
+ data_ptrs[i] = memdup_user((const u8 __user *)
+ (uintptr_t)xfers[i].data,
+ xfers[i].len);
+ if (IS_ERR(data_ptrs[i])) {
+ ret = PTR_ERR(data_ptrs[i]);
+ break;
+ }
+
+ k_xfers[i].len = xfers[i].len;
+ if (xfers[i].rnw) {
+ k_xfers[i].rnw = true;
+ k_xfers[i].data.in = data_ptrs[i];
+ } else {
+ k_xfers[i].rnw = false;
+ k_xfers[i].data.out = data_ptrs[i];
+ }
+ }
+
+ if (ret < 0) {
+ i--;
+ goto err_free_mem;
+ }
+
+ ret = i3c_device_do_priv_xfers(dev, k_xfers, nxfers);
+ if (ret)
+ goto err_free_mem;
+
+ for (i = 0; i < nxfers; i++) {
+ if (xfers[i].rnw) {
+ if (copy_to_user((void __user *)(uintptr_t)xfers[i].data,
+ data_ptrs[i], xfers[i].len))
+ ret = -EFAULT;
+ }
+ }
+
+err_free_mem:
+ for (; i >= 0; i--)
+ kfree(data_ptrs[i]);
+ kfree(data_ptrs);
+err_free_k_xfer:
+ kfree(k_xfers);
+ return ret;
+}
+
+static struct i3c_ioc_priv_xfer *
+i3cdev_get_ioc_priv_xfer(unsigned int cmd, struct i3c_ioc_priv_xfer *u_xfers,
+ unsigned int *nxfers)
+{
+ u32 tmp = _IOC_SIZE(cmd);
+
+ if ((tmp % sizeof(struct i3c_ioc_priv_xfer)) != 0)
+ return ERR_PTR(-EINVAL);
+
+ *nxfers = tmp / sizeof(struct i3c_ioc_priv_xfer);
+ if (*nxfers == 0)
+ return NULL;
+
+ return memdup_user(u_xfers, tmp);
+}
+
+static int
+i3cdev_ioc_priv_xfer(struct i3c_device *i3c, unsigned int cmd,
+ struct i3c_ioc_priv_xfer *u_xfers)
+{
+ struct i3c_ioc_priv_xfer *k_xfers;
+ unsigned int nxfers;
+ int ret;
+
+ k_xfers = i3cdev_get_ioc_priv_xfer(cmd, u_xfers, &nxfers);
+ if (IS_ERR_OR_NULL(k_xfers))
+ return PTR_ERR(k_xfers);
+
+ ret = i3cdev_do_priv_xfer(i3c, k_xfers, nxfers);
+
+ kfree(k_xfers);
+
+ return ret;
+}
+
+static long
+i3cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ struct i3c_device *i3c = file->private_data;
+
+ dev_dbg(&i3c->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n", cmd, arg);
+
+ if (_IOC_TYPE(cmd) != I3C_DEV_IOC_MAGIC)
+ return -ENOTTY;
+
+ /* Check command number and direction */
+ if (_IOC_NR(cmd) == _IOC_NR(I3C_IOC_PRIV_XFER(0)) &&
+ _IOC_DIR(cmd) == (_IOC_READ | _IOC_WRITE))
+ return i3cdev_ioc_priv_xfer(i3c, cmd,
+ (struct i3c_ioc_priv_xfer __user *)arg);
+
+ return 0;
+}
+
+static int i3cdev_open(struct inode *inode, struct file *file)
+{
+ struct i3cdev_data *i3cdev = container_of(inode->i_cdev,
+ struct i3cdev_data,
+ cdev);
+
+ file->private_data = i3cdev->i3c;
+
+ return 0;
+}
+
+static int i3cdev_release(struct inode *inode, struct file *file)
+{
+ file->private_data = NULL;
+
+ return 0;
+}
+
+static const struct file_operations i3cdev_fops = {
+ .owner = THIS_MODULE,
+ .read = i3cdev_read,
+ .write = i3cdev_write,
+ .unlocked_ioctl = i3cdev_ioctl,
+ .compat_ioctl = compat_ptr_ioctl,
+ .open = i3cdev_open,
+ .release = i3cdev_release,
+};
+
+/* ------------------------------------------------------------------------- */
+
+static struct class *i3cdev_class;
+
+static int i3cdev_attach(struct device *dev, void *dummy)
+{
+ struct i3cdev_data *i3cdev;
+ struct i3c_device *i3c;
+ int res;
+
+ if (dev->type == &i3c_masterdev_type || dev->driver)
+ return 0;
+
+ i3c = dev_to_i3cdev(dev);
+
+ /* Get a device */
+ i3cdev = get_free_i3cdev(i3c);
+ if (IS_ERR(i3cdev))
+ return PTR_ERR(i3cdev);
+
+ cdev_init(&i3cdev->cdev, &i3cdev_fops);
+ i3cdev->cdev.owner = THIS_MODULE;
+ res = cdev_add(&i3cdev->cdev,
+ MKDEV(MAJOR(i3cdev_number), i3cdev->id), 1);
+ if (res)
+ goto error_cdev;
+
+ /* register this i3c device with the driver core */
+ i3cdev->dev = device_create(i3cdev_class, &i3c->dev,
+ MKDEV(MAJOR(i3cdev_number), i3cdev->id),
+ NULL, "i3c-%s", dev_name(&i3c->dev));
+ if (IS_ERR(i3cdev->dev)) {
+ res = PTR_ERR(i3cdev->dev);
+ goto error;
+ }
+ pr_debug("i3cdev: I3C device [%s] registered as minor %d\n",
+ dev_name(&i3c->dev), i3cdev->id);
+ return 0;
+
+error:
+ cdev_del(&i3cdev->cdev);
+error_cdev:
+ put_i3cdev(i3cdev);
+ return res;
+}
+
+static int i3cdev_detach(struct device *dev, void *dummy)
+{
+ struct i3cdev_data *i3cdev;
+ struct i3c_device *i3c;
+
+ if (dev->type == &i3c_masterdev_type)
+ return 0;
+
+ i3c = dev_to_i3cdev(dev);
+
+ i3cdev = i3cdev_get_by_i3c(i3c);
+ if (!i3cdev)
+ return 0;
+
+ cdev_del(&i3cdev->cdev);
+ device_destroy(i3cdev_class, MKDEV(MAJOR(i3cdev_number), i3cdev->id));
+ ida_simple_remove(&i3cdev_ida, i3cdev->id);
+ put_i3cdev(i3cdev);
+
+ pr_debug("i3cdev: device [%s] unregistered\n", dev_name(&i3c->dev));
+
+ return 0;
+}
+
+static int i3cdev_notifier_call(struct notifier_block *nb,
+ unsigned long action,
+ void *data)
+{
+ struct device *dev = data;
+
+ switch (action) {
+ case BUS_NOTIFY_ADD_DEVICE:
+ case BUS_NOTIFY_UNBOUND_DRIVER:
+ return i3cdev_attach(dev, NULL);
+ case BUS_NOTIFY_DEL_DEVICE:
+ case BUS_NOTIFY_BOUND_DRIVER:
+ return i3cdev_detach(dev, NULL);
+ }
+
+ return 0;
+}
+
+static struct notifier_block i3c_notifier = {
+ .notifier_call = i3cdev_notifier_call,
+};
+
+static int __init i3cdev_init(void)
+{
+ int res;
+
+ /* Dynamically request unused major number */
+ res = alloc_chrdev_region(&i3cdev_number, 0, I3C_MINORS, "i3c");
+ if (res)
+ goto out;
+
+ /* Create a classe to populate sysfs entries*/
+ i3cdev_class = class_create(THIS_MODULE, "i3cdev");
+ if (IS_ERR(i3cdev_class)) {
+ res = PTR_ERR(i3cdev_class);
+ goto out_unreg_chrdev;
+ }
+
+ /* Keep track of busses which have devices to add or remove later */
+ res = bus_register_notifier(&i3c_bus_type, &i3c_notifier);
+ if (res)
+ goto out_unreg_class;
+
+ /* Bind to already existing device without driver right away */
+ i3c_for_each_dev(NULL, i3cdev_attach);
+
+ return 0;
+
+out_unreg_class:
+ class_destroy(i3cdev_class);
+out_unreg_chrdev:
+ unregister_chrdev_region(i3cdev_number, I3C_MINORS);
+out:
+ pr_err("%s: Driver Initialisation failed\n", __FILE__);
+ return res;
+}
+
+static void __exit i3cdev_exit(void)
+{
+ bus_unregister_notifier(&i3c_bus_type, &i3c_notifier);
+ i3c_for_each_dev(NULL, i3cdev_detach);
+ class_destroy(i3cdev_class);
+ unregister_chrdev_region(i3cdev_number, I3C_MINORS);
+}
+
+MODULE_AUTHOR("Vitor Soares <soares@synopsys.com>");
+MODULE_DESCRIPTION("I3C /dev entries driver");
+MODULE_LICENSE("GPL");
+
+module_init(i3cdev_init);
+module_exit(i3cdev_exit);
diff --git a/include/uapi/linux/i3c/i3cdev.h b/include/uapi/linux/i3c/i3cdev.h
new file mode 100644
index 0000000..0897313
--- /dev/null
+++ b/include/uapi/linux/i3c/i3cdev.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (c) 2019 Synopsys, Inc. and/or its affiliates.
+ *
+ * Author: Vitor Soares <vitor.soares@synopsys.com>
+ */
+
+#ifndef _UAPI_I3C_DEV_H_
+#define _UAPI_I3C_DEV_H_
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+/* IOCTL commands */
+#define I3C_DEV_IOC_MAGIC 0x07
+
+/**
+ * struct i3c_ioc_priv_xfer - I3C SDR ioctl private transfer
+ * @data: Holds pointer to userspace buffer with transmit data.
+ * @len: Length of data buffer buffers, in bytes.
+ * @rnw: encodes the transfer direction. true for a read, false for a write
+ */
+struct i3c_ioc_priv_xfer {
+ __u64 data;
+ __u16 len;
+ __u8 rnw;
+ __u8 pad[5];
+};
+
+
+#define I3C_PRIV_XFER_SIZE(N) \
+ ((((sizeof(struct i3c_ioc_priv_xfer)) * (N)) < (1 << _IOC_SIZEBITS)) \
+ ? ((sizeof(struct i3c_ioc_priv_xfer)) * (N)) : 0)
+
+#define I3C_IOC_PRIV_XFER(N) \
+ _IOC(_IOC_READ|_IOC_WRITE, I3C_DEV_IOC_MAGIC, 30, I3C_PRIV_XFER_SIZE(N))
+
+#endif
--
2.7.4
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