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Subject[PATCH v2 7/7] mhi_bus: dev: uci: add user space interface driver
Date
This module allows user space clients to transfer data
between external modem and host using standard file
operations.

Signed-off-by: Sujeev Dias <sdias@codeaurora.org>
Reviewed-by: Tony Truong <truong@codeaurora.org>
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
---
arch/arm64/configs/defconfig | 1 +
drivers/bus/Kconfig | 1 +
drivers/bus/mhi/Makefile | 3 +-
drivers/bus/mhi/devices/Kconfig | 13 +
drivers/bus/mhi/devices/Makefile | 1 +
drivers/bus/mhi/devices/mhi_uci.c | 590 ++++++++++++++++++++++++++++++++++++++
6 files changed, 608 insertions(+), 1 deletion(-)
create mode 100644 drivers/bus/mhi/devices/Kconfig
create mode 100644 drivers/bus/mhi/devices/Makefile
create mode 100644 drivers/bus/mhi/devices/mhi_uci.c

diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index fd36426..7f68d706 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -169,6 +169,7 @@ CONFIG_DEVTMPFS_MOUNT=y
CONFIG_DMA_CMA=y
CONFIG_MHI_BUS=y
CONFIG_MHI_QCOM=y
+CONFIG_MHI_UCI=y
CONFIG_MTD=y
CONFIG_MTD_BLOCK=y
CONFIG_MTD_M25P80=y
diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 8c6827a..cb10366 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -181,5 +181,6 @@ config MHI_BUS

source "drivers/bus/fsl-mc/Kconfig"
source drivers/bus/mhi/controllers/Kconfig
+source drivers/bus/mhi/devices/Kconfig

endmenu
diff --git a/drivers/bus/mhi/Makefile b/drivers/bus/mhi/Makefile
index 3458ba3..2382e04 100644
--- a/drivers/bus/mhi/Makefile
+++ b/drivers/bus/mhi/Makefile
@@ -4,4 +4,5 @@

# core layer
obj-y += core/
-obj-y += controllers/
\ No newline at end of file
+obj-y += controllers/
+obj-y += devices/
diff --git a/drivers/bus/mhi/devices/Kconfig b/drivers/bus/mhi/devices/Kconfig
new file mode 100644
index 0000000..45cd742
--- /dev/null
+++ b/drivers/bus/mhi/devices/Kconfig
@@ -0,0 +1,13 @@
+menu "MHI device support"
+
+config MHI_UCI
+ tristate "MHI UCI"
+ depends on MHI_BUS
+ help
+ MHI based uci driver is for transferring data between host and
+ modem using standard file operations from user space. Open, read,
+ write, ioctl, and close operations are supported by this driver.
+ Please check mhi_uci_match_table for all supported channels that
+ are exposed to userspace.
+
+endmenu
diff --git a/drivers/bus/mhi/devices/Makefile b/drivers/bus/mhi/devices/Makefile
new file mode 100644
index 0000000..ddc0613
--- /dev/null
+++ b/drivers/bus/mhi/devices/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_MHI_UCI) +=mhi_uci.o
diff --git a/drivers/bus/mhi/devices/mhi_uci.c b/drivers/bus/mhi/devices/mhi_uci.c
new file mode 100644
index 0000000..ad60a15
--- /dev/null
+++ b/drivers/bus/mhi/devices/mhi_uci.c
@@ -0,0 +1,590 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018, The Linux Foundation. All rights reserved.
+ *
+ */
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/dma-direction.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+#include <linux/uaccess.h>
+#include <linux/mhi.h>
+
+#define DEVICE_NAME "mhi"
+#define MHI_UCI_DRIVER_NAME "mhi_uci"
+
+struct uci_chan {
+ wait_queue_head_t wq;
+ spinlock_t lock;
+ struct list_head pending; /* user space waiting to read */
+ struct uci_buf *cur_buf; /* current buffer user space reading */
+ size_t rx_size;
+};
+
+struct uci_buf {
+ void *data;
+ size_t len;
+ struct list_head node;
+};
+
+struct uci_dev {
+ struct list_head node;
+ dev_t devt;
+ struct device *dev;
+ struct mhi_device *mhi_dev;
+ const char *chan;
+ struct mutex mutex; /* sync open and close */
+ struct uci_chan ul_chan;
+ struct uci_chan dl_chan;
+ size_t mtu;
+ int ref_count;
+ bool enabled;
+};
+
+struct mhi_uci_drv {
+ struct list_head head;
+ struct mutex lock;
+ struct class *class;
+ int major;
+ dev_t dev_t;
+};
+
+#define MAX_UCI_DEVICES (64)
+
+static DECLARE_BITMAP(uci_minors, MAX_UCI_DEVICES);
+static struct mhi_uci_drv mhi_uci_drv;
+
+static int mhi_queue_inbound(struct uci_dev *uci_dev)
+{
+ struct mhi_device *mhi_dev = uci_dev->mhi_dev;
+ int nr_trbs = mhi_get_no_free_descriptors(mhi_dev, DMA_FROM_DEVICE);
+ size_t mtu = uci_dev->mtu;
+ void *buf;
+ struct uci_buf *uci_buf;
+ int ret = -EIO, i;
+
+ for (i = 0; i < nr_trbs; i++) {
+ buf = kmalloc(mtu + sizeof(*uci_buf), GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ uci_buf = buf + mtu;
+ uci_buf->data = buf;
+
+ ret = mhi_queue_transfer(mhi_dev, DMA_FROM_DEVICE, buf, mtu,
+ MHI_EOT);
+ if (ret) {
+ kfree(buf);
+ return ret;
+ }
+ }
+
+ return ret;
+}
+
+static long mhi_uci_ioctl(struct file *file,
+ unsigned int cmd,
+ unsigned long arg)
+{
+ struct uci_dev *uci_dev = file->private_data;
+ struct mhi_device *mhi_dev = uci_dev->mhi_dev;
+ long ret = -ERESTARTSYS;
+
+ mutex_lock(&uci_dev->mutex);
+ if (uci_dev->enabled)
+ ret = mhi_ioctl(mhi_dev, cmd, arg);
+ mutex_unlock(&uci_dev->mutex);
+
+ return ret;
+}
+
+static int mhi_uci_release(struct inode *inode, struct file *file)
+{
+ struct uci_dev *uci_dev = file->private_data;
+
+ mutex_lock(&uci_dev->mutex);
+ uci_dev->ref_count--;
+ if (!uci_dev->ref_count) {
+ struct uci_buf *itr, *tmp;
+ struct uci_chan *uci_chan;
+
+ if (uci_dev->enabled)
+ mhi_unprepare_from_transfer(uci_dev->mhi_dev);
+
+ /* clean inbound channel */
+ uci_chan = &uci_dev->dl_chan;
+ list_for_each_entry_safe(itr, tmp, &uci_chan->pending, node) {
+ list_del(&itr->node);
+ kfree(itr->data);
+ }
+ if (uci_chan->cur_buf)
+ kfree(uci_chan->cur_buf->data);
+
+ uci_chan->cur_buf = NULL;
+
+ if (!uci_dev->enabled) {
+ mutex_unlock(&uci_dev->mutex);
+ mutex_destroy(&uci_dev->mutex);
+ clear_bit(MINOR(uci_dev->devt), uci_minors);
+ kfree(uci_dev);
+ return 0;
+ }
+ }
+
+ mutex_unlock(&uci_dev->mutex);
+
+ return 0;
+}
+
+static unsigned int mhi_uci_poll(struct file *file, poll_table *wait)
+{
+ struct uci_dev *uci_dev = file->private_data;
+ struct mhi_device *mhi_dev = uci_dev->mhi_dev;
+ struct uci_chan *uci_chan;
+ unsigned int mask = 0;
+
+ poll_wait(file, &uci_dev->dl_chan.wq, wait);
+ poll_wait(file, &uci_dev->ul_chan.wq, wait);
+
+ uci_chan = &uci_dev->dl_chan;
+ spin_lock_bh(&uci_chan->lock);
+ if (!uci_dev->enabled)
+ mask = POLLERR;
+ else if (!list_empty(&uci_chan->pending) || uci_chan->cur_buf)
+ mask |= POLLIN | POLLRDNORM;
+
+ spin_unlock_bh(&uci_chan->lock);
+
+ uci_chan = &uci_dev->ul_chan;
+ spin_lock_bh(&uci_chan->lock);
+ if (!uci_dev->enabled)
+ mask |= POLLERR;
+ else if (mhi_get_no_free_descriptors(mhi_dev, DMA_TO_DEVICE) > 0)
+ mask |= POLLOUT | POLLWRNORM;
+
+ spin_unlock_bh(&uci_chan->lock);
+
+ return mask;
+}
+
+static ssize_t mhi_uci_write(struct file *file,
+ const char __user *buf,
+ size_t count,
+ loff_t *offp)
+{
+ struct uci_dev *uci_dev = file->private_data;
+ struct mhi_device *mhi_dev = uci_dev->mhi_dev;
+ struct uci_chan *uci_chan = &uci_dev->ul_chan;
+ size_t bytes_xfered = 0;
+ int ret, nr_avail;
+
+ if (!buf || !count)
+ return -EINVAL;
+
+ /* confirm channel is active */
+ spin_lock_bh(&uci_chan->lock);
+ if (!uci_dev->enabled) {
+ spin_unlock_bh(&uci_chan->lock);
+ return -ERESTARTSYS;
+ }
+
+ while (count) {
+ size_t xfer_size;
+ void *kbuf;
+ enum MHI_FLAGS flags;
+
+ spin_unlock_bh(&uci_chan->lock);
+
+ /* wait for free descriptors */
+ ret = wait_event_interruptible(uci_chan->wq,
+ (!uci_dev->enabled) ||
+ (nr_avail = mhi_get_no_free_descriptors(mhi_dev,
+ DMA_TO_DEVICE)) > 0);
+
+ if (ret == -ERESTARTSYS || !uci_dev->enabled)
+ return -ERESTARTSYS;
+
+ xfer_size = min_t(size_t, count, uci_dev->mtu);
+ kbuf = kmalloc(xfer_size, GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+
+ ret = copy_from_user(kbuf, buf, xfer_size);
+ if (unlikely(ret)) {
+ kfree(kbuf);
+ return ret;
+ }
+
+ spin_lock_bh(&uci_chan->lock);
+
+ /* if ring is full after this force EOT */
+ if (nr_avail > 1 && (count - xfer_size))
+ flags = MHI_CHAIN;
+ else
+ flags = MHI_EOT;
+
+ if (uci_dev->enabled)
+ ret = mhi_queue_transfer(mhi_dev, DMA_TO_DEVICE, kbuf,
+ xfer_size, flags);
+ else
+ ret = -ERESTARTSYS;
+
+ if (ret) {
+ kfree(kbuf);
+ goto sys_interrupt;
+ }
+
+ bytes_xfered += xfer_size;
+ count -= xfer_size;
+ buf += xfer_size;
+ }
+
+ spin_unlock_bh(&uci_chan->lock);
+
+ return bytes_xfered;
+
+sys_interrupt:
+ spin_unlock_bh(&uci_chan->lock);
+
+ return ret;
+}
+
+static ssize_t mhi_uci_read(struct file *file,
+ char __user *buf,
+ size_t count,
+ loff_t *ppos)
+{
+ struct uci_dev *uci_dev = file->private_data;
+ struct mhi_device *mhi_dev = uci_dev->mhi_dev;
+ struct uci_chan *uci_chan = &uci_dev->dl_chan;
+ struct uci_buf *uci_buf;
+ char *ptr;
+ size_t to_copy;
+ int ret = 0;
+
+ if (!buf)
+ return -EINVAL;
+
+ /* confirm channel is active */
+ spin_lock_bh(&uci_chan->lock);
+ if (!uci_dev->enabled) {
+ spin_unlock_bh(&uci_chan->lock);
+ return -ERESTARTSYS;
+ }
+
+ /* No data available to read, wait */
+ if (!uci_chan->cur_buf && list_empty(&uci_chan->pending)) {
+
+ spin_unlock_bh(&uci_chan->lock);
+ ret = wait_event_interruptible(uci_chan->wq,
+ (!uci_dev->enabled ||
+ !list_empty(&uci_chan->pending)));
+ if (ret == -ERESTARTSYS)
+ return -ERESTARTSYS;
+
+ spin_lock_bh(&uci_chan->lock);
+ if (!uci_dev->enabled) {
+ ret = -ERESTARTSYS;
+ goto read_error;
+ }
+ }
+
+ /* new read, get the next descriptor from the list */
+ if (!uci_chan->cur_buf) {
+ uci_buf = list_first_entry_or_null(&uci_chan->pending,
+ struct uci_buf, node);
+ if (unlikely(!uci_buf)) {
+ ret = -EIO;
+ goto read_error;
+ }
+
+ list_del(&uci_buf->node);
+ uci_chan->cur_buf = uci_buf;
+ uci_chan->rx_size = uci_buf->len;
+ }
+
+ uci_buf = uci_chan->cur_buf;
+ spin_unlock_bh(&uci_chan->lock);
+
+ /* Copy the buffer to user space */
+ to_copy = min_t(size_t, count, uci_chan->rx_size);
+ ptr = uci_buf->data + (uci_buf->len - uci_chan->rx_size);
+ ret = copy_to_user(buf, ptr, to_copy);
+ if (ret)
+ return ret;
+
+ uci_chan->rx_size -= to_copy;
+
+ /* we finished with this buffer, queue it back to hardware */
+ if (!uci_chan->rx_size) {
+ spin_lock_bh(&uci_chan->lock);
+ uci_chan->cur_buf = NULL;
+
+ if (uci_dev->enabled)
+ ret = mhi_queue_transfer(mhi_dev, DMA_FROM_DEVICE,
+ uci_buf->data, uci_dev->mtu,
+ MHI_EOT);
+ else
+ ret = -ERESTARTSYS;
+
+ if (ret) {
+ kfree(uci_buf->data);
+ goto read_error;
+ }
+
+ spin_unlock_bh(&uci_chan->lock);
+ }
+
+ return to_copy;
+
+read_error:
+ spin_unlock_bh(&uci_chan->lock);
+
+ return ret;
+}
+
+static int mhi_uci_open(struct inode *inode, struct file *filp)
+{
+ struct uci_dev *uci_dev;
+ int ret = -EIO;
+ struct uci_buf *buf_itr, *tmp;
+ struct uci_chan *dl_chan;
+
+ mutex_lock(&mhi_uci_drv.lock);
+ list_for_each_entry(uci_dev, &mhi_uci_drv.head, node) {
+ if (uci_dev->devt == inode->i_rdev) {
+ ret = 0;
+ break;
+ }
+ }
+ mutex_unlock(&mhi_uci_drv.lock);
+
+ /* could not find a minor node */
+ if (ret)
+ return ret;
+
+ mutex_lock(&uci_dev->mutex);
+ if (!uci_dev->enabled)
+ goto error_open_chan;
+
+ uci_dev->ref_count++;
+
+ if (uci_dev->ref_count == 1) {
+ ret = mhi_prepare_for_transfer(uci_dev->mhi_dev);
+ if (ret) {
+ uci_dev->ref_count--;
+ goto error_open_chan;
+ }
+
+ ret = mhi_queue_inbound(uci_dev);
+ if (ret)
+ goto error_rx_queue;
+ }
+
+ filp->private_data = uci_dev;
+ mutex_unlock(&uci_dev->mutex);
+
+ return 0;
+
+ error_rx_queue:
+ dl_chan = &uci_dev->dl_chan;
+ mhi_unprepare_from_transfer(uci_dev->mhi_dev);
+ list_for_each_entry_safe(buf_itr, tmp, &dl_chan->pending, node) {
+ list_del(&buf_itr->node);
+ kfree(buf_itr->data);
+ }
+
+ error_open_chan:
+ mutex_unlock(&uci_dev->mutex);
+
+ return ret;
+}
+
+static const struct file_operations mhidev_fops = {
+ .open = mhi_uci_open,
+ .release = mhi_uci_release,
+ .read = mhi_uci_read,
+ .write = mhi_uci_write,
+ .poll = mhi_uci_poll,
+ .unlocked_ioctl = mhi_uci_ioctl,
+};
+
+static void mhi_uci_remove(struct mhi_device *mhi_dev)
+{
+ struct uci_dev *uci_dev = mhi_device_get_devdata(mhi_dev);
+
+ /* disable the node */
+ mutex_lock(&uci_dev->mutex);
+ spin_lock_irq(&uci_dev->dl_chan.lock);
+ spin_lock_irq(&uci_dev->ul_chan.lock);
+ uci_dev->enabled = false;
+ spin_unlock_irq(&uci_dev->ul_chan.lock);
+ spin_unlock_irq(&uci_dev->dl_chan.lock);
+ wake_up(&uci_dev->dl_chan.wq);
+ wake_up(&uci_dev->ul_chan.wq);
+
+ /* delete the node to prevent new opens */
+ device_destroy(mhi_uci_drv.class, uci_dev->devt);
+ uci_dev->dev = NULL;
+ mutex_lock(&mhi_uci_drv.lock);
+ list_del(&uci_dev->node);
+ mutex_unlock(&mhi_uci_drv.lock);
+
+ /* safe to free memory only if all file nodes are closed */
+ if (!uci_dev->ref_count) {
+ mutex_unlock(&uci_dev->mutex);
+ mutex_destroy(&uci_dev->mutex);
+ clear_bit(MINOR(uci_dev->devt), uci_minors);
+ kfree(uci_dev);
+ return;
+ }
+
+ mutex_unlock(&uci_dev->mutex);
+}
+
+static int mhi_uci_probe(struct mhi_device *mhi_dev,
+ const struct mhi_device_id *id)
+{
+ struct uci_dev *uci_dev;
+ int minor;
+ int dir;
+
+ uci_dev = kzalloc(sizeof(*uci_dev), GFP_KERNEL);
+ if (!uci_dev)
+ return -ENOMEM;
+
+ mutex_init(&uci_dev->mutex);
+ uci_dev->mhi_dev = mhi_dev;
+
+ minor = find_first_zero_bit(uci_minors, MAX_UCI_DEVICES);
+ if (minor >= MAX_UCI_DEVICES) {
+ kfree(uci_dev);
+ return -ENOSPC;
+ }
+
+ mutex_lock(&uci_dev->mutex);
+ mutex_lock(&mhi_uci_drv.lock);
+
+ uci_dev->devt = MKDEV(mhi_uci_drv.major, minor);
+ uci_dev->dev = device_create(mhi_uci_drv.class, &mhi_dev->dev,
+ uci_dev->devt, uci_dev,
+ DEVICE_NAME "_%04x_%02u.%02u.%02u%s%d",
+ mhi_dev->dev_id, mhi_dev->domain,
+ mhi_dev->bus, mhi_dev->slot, "_pipe_",
+ mhi_dev->ul_chan_id);
+ set_bit(minor, uci_minors);
+
+ for (dir = 0; dir < 2; dir++) {
+ struct uci_chan *uci_chan = (dir) ?
+ &uci_dev->ul_chan : &uci_dev->dl_chan;
+ spin_lock_init(&uci_chan->lock);
+ init_waitqueue_head(&uci_chan->wq);
+ INIT_LIST_HEAD(&uci_chan->pending);
+ }
+
+ uci_dev->mtu = min_t(size_t, id->driver_data, mhi_dev->mtu);
+ mhi_device_set_devdata(mhi_dev, uci_dev);
+ uci_dev->enabled = true;
+
+ list_add(&uci_dev->node, &mhi_uci_drv.head);
+ mutex_unlock(&mhi_uci_drv.lock);
+ mutex_unlock(&uci_dev->mutex);
+
+ return 0;
+};
+
+static void mhi_ul_xfer_cb(struct mhi_device *mhi_dev,
+ struct mhi_result *mhi_result)
+{
+ struct uci_dev *uci_dev = mhi_device_get_devdata(mhi_dev);
+ struct uci_chan *uci_chan = &uci_dev->ul_chan;
+
+ kfree(mhi_result->buf_addr);
+ if (!mhi_result->transaction_status)
+ wake_up(&uci_chan->wq);
+}
+
+static void mhi_dl_xfer_cb(struct mhi_device *mhi_dev,
+ struct mhi_result *mhi_result)
+{
+ struct uci_dev *uci_dev = mhi_device_get_devdata(mhi_dev);
+ struct uci_chan *uci_chan = &uci_dev->dl_chan;
+ unsigned long flags;
+ struct uci_buf *buf;
+
+ if (mhi_result->transaction_status == -ENOTCONN) {
+ kfree(mhi_result->buf_addr);
+ return;
+ }
+
+ spin_lock_irqsave(&uci_chan->lock, flags);
+ buf = mhi_result->buf_addr + uci_dev->mtu;
+ buf->data = mhi_result->buf_addr;
+ buf->len = mhi_result->bytes_xferd;
+ list_add_tail(&buf->node, &uci_chan->pending);
+ spin_unlock_irqrestore(&uci_chan->lock, flags);
+
+ wake_up(&uci_chan->wq);
+}
+
+/* .driver_data stores max mtu */
+static const struct mhi_device_id mhi_uci_match_table[] = {
+ { .chan = "LOOPBACK", .driver_data = 0x1000 },
+ { .chan = "SAHARA", .driver_data = 0x8000 },
+ { .chan = "EFS", .driver_data = 0x1000 },
+ { .chan = "QMI0", .driver_data = 0x1000 },
+ { .chan = "QMI1", .driver_data = 0x1000 },
+ { .chan = "TF", .driver_data = 0x1000 },
+ { .chan = "BL", .driver_data = 0x1000 },
+ { .chan = "DUN", .driver_data = 0x1000 },
+ {},
+};
+
+static struct mhi_driver mhi_uci_driver = {
+ .id_table = mhi_uci_match_table,
+ .remove = mhi_uci_remove,
+ .probe = mhi_uci_probe,
+ .ul_xfer_cb = mhi_ul_xfer_cb,
+ .dl_xfer_cb = mhi_dl_xfer_cb,
+ .driver = {
+ .name = MHI_UCI_DRIVER_NAME,
+ .owner = THIS_MODULE,
+ },
+};
+
+static int mhi_uci_init(void)
+{
+ int ret;
+
+ ret = register_chrdev(0, MHI_UCI_DRIVER_NAME, &mhidev_fops);
+ if (ret < 0)
+ return ret;
+
+ mhi_uci_drv.major = ret;
+ mhi_uci_drv.class = class_create(THIS_MODULE, MHI_UCI_DRIVER_NAME);
+ if (IS_ERR(mhi_uci_drv.class))
+ return -ENODEV;
+
+ mutex_init(&mhi_uci_drv.lock);
+ INIT_LIST_HEAD(&mhi_uci_drv.head);
+
+ ret = mhi_driver_register(&mhi_uci_driver);
+ if (ret)
+ class_destroy(mhi_uci_drv.class);
+
+ return ret;
+}
+
+module_init(mhi_uci_init);
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("MHI_UCI");
+MODULE_DESCRIPTION("MHI UCI Driver");
--
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