Messages in this thread Patch in this message | | | From | Vitor Soares <> | Subject | [PATCH v3 4/5] i3c: add i3cdev module to expose i3c dev in /dev | Date | Wed, 19 Feb 2020 01:20:42 +0100 |
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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> --- Changes in v3: Use the xfer_lock to prevent device detach during ioctl call Expose i3cdev under /dev/bus/i3c/ folder like usb does Change NOTIFY_BOUND to NOTIFY_BIND, this allows the device detach occur before driver->probe Avoid use of IS_ERR_OR_NULL Use u64_to_user_ptr instead of (void __user *)(uintptr_t) cast Allocate k_xfer and data_ptrs at once to eliminate duble allocation check Pass i3cdev to dev->driver_data Make all minors available
Changes in v2: Use IDR api for minor numbering Modify ioctl struct Fix SPDX license
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..1a6bd35 --- /dev/null +++ b/drivers/i3c/i3cdev.c @@ -0,0 +1,429 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2020 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/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 i3c_device *i3c; + struct device *dev; + struct mutex xfer_lock; /* prevent detach while transferring */ + struct cdev cdev; + int id; +}; + +static DEFINE_IDA(i3cdev_ida); +static dev_t i3cdev_number; +#define I3C_MINORS (MINORMASK + 1) + +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; + i3cdev_set_drvdata(i3c, i3cdev); + + return i3cdev; +} + +static void put_i3cdev(struct i3cdev_data *i3cdev) +{ + i3cdev_set_drvdata(i3cdev->i3c, NULL); + kfree(i3cdev); +} + +static ssize_t +i3cdev_read(struct file *file, char __user *buf, size_t count, loff_t *f_pos) +{ + struct i3cdev_data *i3cdev = file->private_data; + struct i3c_device *i3c = i3cdev->i3c; + struct i3c_priv_xfer xfers = { + .rnw = true, + .len = count, + }; + int ret = -EACCES; + char *tmp; + + mutex_lock(&i3cdev->xfer_lock); + if (i3c->dev.driver) + goto err_out; + + 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, xfers.len) ? -EFAULT : xfers.len; + + kfree(tmp); + +err_out: + mutex_unlock(&i3cdev->xfer_lock); + return ret; +} + +static ssize_t +i3cdev_write(struct file *file, const char __user *buf, size_t count, + loff_t *f_pos) +{ + struct i3cdev_data *i3cdev = file->private_data; + struct i3c_device *i3c = i3cdev->i3c; + struct i3c_priv_xfer xfers = { + .rnw = false, + .len = count, + }; + int ret = -EACCES; + char *tmp; + + mutex_lock(&i3cdev->xfer_lock); + if (i3c->dev.driver) + goto err_out; + + 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); + +err_out: + mutex_unlock(&i3cdev->xfer_lock); + 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; + + /* Since we have nxfers we may allocate k_xfer + *data_ptrs together */ + k_xfers = kcalloc(nxfers, sizeof(*k_xfers) + sizeof(*data_ptrs), + GFP_KERNEL); + if (!k_xfers) + return -ENOMEM; + + /* set data_ptrs to be after nxfers * i3c_priv_xfer */ + data_ptrs = (void *)k_xfers + (nxfers * sizeof(*k_xfers)); + + 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(u64_to_user_ptr(xfers[i].data), + data_ptrs[i], xfers[i].len)) + ret = -EFAULT; + } + } + +err_free_mem: + for (; i >= 0; i--) + kfree(data_ptrs[i]); + 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 ERR_PTR(-EINVAL); + + 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(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 i3cdev_data *i3cdev = file->private_data; + struct i3c_device *i3c = i3cdev->i3c; + int ret = -EACCES; + + dev_dbg(&i3c->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n", cmd, arg); + + if (_IOC_TYPE(cmd) != I3C_DEV_IOC_MAGIC) + return -ENOTTY; + + /* Use the xfer_lock to prevent device detach during ioctl call */ + mutex_lock(&i3cdev->xfer_lock); + if (i3c->dev.driver) + goto err_no_dev; + + /* Check command number and direction */ + if (_IOC_NR(cmd) == _IOC_NR(I3C_IOC_PRIV_XFER(0)) && + _IOC_DIR(cmd) == (_IOC_READ | _IOC_WRITE)) + ret = i3cdev_ioc_priv_xfer(i3c, cmd, + (struct i3c_ioc_priv_xfer __user *)arg); + +err_no_dev: + mutex_unlock(&i3cdev->xfer_lock); + return ret; +} + +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; + + 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); + + mutex_init(&i3cdev->xfer_lock); + 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, "bus!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_drvdata(i3c); + if (!i3cdev) + return 0; + + /* Prevent transfers while cdev removal */ + mutex_lock(&i3cdev->xfer_lock); + cdev_del(&i3cdev->cdev); + device_destroy(i3cdev_class, MKDEV(MAJOR(i3cdev_number), i3cdev->id)); + mutex_unlock(&i3cdev->xfer_lock); + + 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_BIND_DRIVER: + return i3cdev_detach(dev, NULL); + } + + return 0; +} + +static struct notifier_block i3cdev_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, &i3cdev_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, &i3cdev_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..656a686 --- /dev/null +++ b/include/uapi/linux/i3c/i3cdev.h @@ -0,0 +1,37 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* + * Copyright (c) 2020 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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