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virtio_console: Add support for remoteproc serial
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Add a simple serial connection driver called
VIRTIO_ID_RPROC_SERIAL (11) for communicating with a
remote processor in an asymmetric multi-processing
configuration.

This implementation reuses the existing virtio_console
implementation, and adds support for DMA allocation
of data buffers and disables use of tty console and
the virtio control queue.

Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Sjur Brændeland authored and Rusty Russell committed Dec 18, 2012
1 parent 276a3e9 commit 1b63704
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Showing 2 changed files with 170 additions and 23 deletions.
192 changes: 169 additions & 23 deletions drivers/char/virtio_console.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,8 +37,12 @@
#include <linux/wait.h>
#include <linux/workqueue.h>
#include <linux/module.h>
#include <linux/dma-mapping.h>
#include <linux/kconfig.h>
#include "../tty/hvc/hvc_console.h"

#define is_rproc_enabled IS_ENABLED(CONFIG_REMOTEPROC)

/*
* This is a global struct for storing common data for all the devices
* this driver handles.
Expand Down Expand Up @@ -112,6 +116,15 @@ struct port_buffer {
/* offset in the buf from which to consume data */
size_t offset;

/* DMA address of buffer */
dma_addr_t dma;

/* Device we got DMA memory from */
struct device *dev;

/* List of pending dma buffers to free */
struct list_head list;

/* If sgpages == 0 then buf is used */
unsigned int sgpages;

Expand Down Expand Up @@ -331,6 +344,11 @@ static bool is_console_port(struct port *port)
return false;
}

static bool is_rproc_serial(const struct virtio_device *vdev)
{
return is_rproc_enabled && vdev->id.device == VIRTIO_ID_RPROC_SERIAL;
}

static inline bool use_multiport(struct ports_device *portdev)
{
/*
Expand All @@ -342,26 +360,71 @@ static inline bool use_multiport(struct ports_device *portdev)
return portdev->vdev->features[0] & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
}

static void free_buf(struct port_buffer *buf)
static DEFINE_SPINLOCK(dma_bufs_lock);
static LIST_HEAD(pending_free_dma_bufs);

static void free_buf(struct port_buffer *buf, bool can_sleep)
{
unsigned int i;

kfree(buf->buf);
for (i = 0; i < buf->sgpages; i++) {
struct page *page = sg_page(&buf->sg[i]);
if (!page)
break;
put_page(page);
}

if (!buf->dev) {
kfree(buf->buf);
} else if (is_rproc_enabled) {
unsigned long flags;

/* dma_free_coherent requires interrupts to be enabled. */
if (!can_sleep) {
/* queue up dma-buffers to be freed later */
spin_lock_irqsave(&dma_bufs_lock, flags);
list_add_tail(&buf->list, &pending_free_dma_bufs);
spin_unlock_irqrestore(&dma_bufs_lock, flags);
return;
}
dma_free_coherent(buf->dev, buf->size, buf->buf, buf->dma);

/* Release device refcnt and allow it to be freed */
put_device(buf->dev);
}

kfree(buf);
}

static void reclaim_dma_bufs(void)
{
unsigned long flags;
struct port_buffer *buf, *tmp;
LIST_HEAD(tmp_list);

if (list_empty(&pending_free_dma_bufs))
return;

/* Create a copy of the pending_free_dma_bufs while holding the lock */
spin_lock_irqsave(&dma_bufs_lock, flags);
list_cut_position(&tmp_list, &pending_free_dma_bufs,
pending_free_dma_bufs.prev);
spin_unlock_irqrestore(&dma_bufs_lock, flags);

/* Release the dma buffers, without irqs enabled */
list_for_each_entry_safe(buf, tmp, &tmp_list, list) {
list_del(&buf->list);
free_buf(buf, true);
}
}

static struct port_buffer *alloc_buf(struct virtqueue *vq, size_t buf_size,
int pages)
{
struct port_buffer *buf;

reclaim_dma_bufs();

/*
* Allocate buffer and the sg list. The sg list array is allocated
* directly after the port_buffer struct.
Expand All @@ -373,11 +436,34 @@ static struct port_buffer *alloc_buf(struct virtqueue *vq, size_t buf_size,

buf->sgpages = pages;
if (pages > 0) {
buf->dev = NULL;
buf->buf = NULL;
return buf;
}

buf->buf = kmalloc(buf_size, GFP_KERNEL);
if (is_rproc_serial(vq->vdev)) {
/*
* Allocate DMA memory from ancestor. When a virtio
* device is created by remoteproc, the DMA memory is
* associated with the grandparent device:
* vdev => rproc => platform-dev.
* The code here would have been less quirky if
* DMA_MEMORY_INCLUDES_CHILDREN had been supported
* in dma-coherent.c
*/
if (!vq->vdev->dev.parent || !vq->vdev->dev.parent->parent)
goto free_buf;
buf->dev = vq->vdev->dev.parent->parent;

/* Increase device refcnt to avoid freeing it */
get_device(buf->dev);
buf->buf = dma_alloc_coherent(buf->dev, buf_size, &buf->dma,
GFP_KERNEL);
} else {
buf->dev = NULL;
buf->buf = kmalloc(buf_size, GFP_KERNEL);
}

if (!buf->buf)
goto free_buf;
buf->len = 0;
Expand Down Expand Up @@ -446,7 +532,7 @@ static void discard_port_data(struct port *port)
port->stats.bytes_discarded += buf->len - buf->offset;
if (add_inbuf(port->in_vq, buf) < 0) {
err++;
free_buf(buf);
free_buf(buf, false);
}
port->inbuf = NULL;
buf = get_inbuf(port);
Expand Down Expand Up @@ -518,7 +604,7 @@ static void reclaim_consumed_buffers(struct port *port)
return;
}
while ((buf = virtqueue_get_buf(port->out_vq, &len))) {
free_buf(buf);
free_buf(buf, false);
port->outvq_full = false;
}
}
Expand Down Expand Up @@ -765,7 +851,7 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
goto out;

free_buf:
free_buf(buf);
free_buf(buf, true);
out:
return ret;
}
Expand Down Expand Up @@ -839,6 +925,15 @@ static ssize_t port_fops_splice_write(struct pipe_inode_info *pipe,
.u.data = &sgl,
};

/*
* Rproc_serial does not yet support splice. To support splice
* pipe_to_sg() must allocate dma-buffers and copy content from
* regular pages to dma pages. And alloc_buf and free_buf must
* support allocating and freeing such a list of dma-buffers.
*/
if (is_rproc_serial(port->out_vq->vdev))
return -EINVAL;

ret = wait_port_writable(port, filp->f_flags & O_NONBLOCK);
if (ret < 0)
return ret;
Expand All @@ -857,7 +952,7 @@ static ssize_t port_fops_splice_write(struct pipe_inode_info *pipe,
ret = __send_to_port(port, buf->sg, sgl.n, sgl.len, buf, true);

if (unlikely(ret <= 0))
kfree(sgl.sg);
free_buf(buf, true);
return ret;
}

Expand Down Expand Up @@ -906,6 +1001,7 @@ static int port_fops_release(struct inode *inode, struct file *filp)
reclaim_consumed_buffers(port);
spin_unlock_irq(&port->outvq_lock);

reclaim_dma_bufs();
/*
* Locks aren't necessary here as a port can't be opened after
* unplug, and if a port isn't unplugged, a kref would already
Expand Down Expand Up @@ -1057,7 +1153,10 @@ static void resize_console(struct port *port)
return;

vdev = port->portdev->vdev;
if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_SIZE))

/* Don't test F_SIZE at all if we're rproc: not a valid feature! */
if (!is_rproc_serial(vdev) &&
virtio_has_feature(vdev, VIRTIO_CONSOLE_F_SIZE))
hvc_resize(port->cons.hvc, port->cons.ws);
}

Expand Down Expand Up @@ -1249,7 +1348,7 @@ static unsigned int fill_queue(struct virtqueue *vq, spinlock_t *lock)
ret = add_inbuf(vq, buf);
if (ret < 0) {
spin_unlock_irq(lock);
free_buf(buf);
free_buf(buf, true);
break;
}
nr_added_bufs++;
Expand Down Expand Up @@ -1337,10 +1436,18 @@ static int add_port(struct ports_device *portdev, u32 id)
goto free_device;
}

/*
* If we're not using multiport support, this has to be a console port
*/
if (!use_multiport(port->portdev)) {
if (is_rproc_serial(port->portdev->vdev))
/*
* For rproc_serial assume remote processor is connected.
* rproc_serial does not want the console port, only
* the generic port implementation.
*/
port->host_connected = true;
else if (!use_multiport(port->portdev)) {
/*
* If we're not using multiport support,
* this has to be a console port.
*/
err = init_port_console(port);
if (err)
goto free_inbufs;
Expand Down Expand Up @@ -1373,7 +1480,7 @@ static int add_port(struct ports_device *portdev, u32 id)

free_inbufs:
while ((buf = virtqueue_detach_unused_buf(port->in_vq)))
free_buf(buf);
free_buf(buf, true);
free_device:
device_destroy(pdrvdata.class, port->dev->devt);
free_cdev:
Expand Down Expand Up @@ -1415,11 +1522,11 @@ static void remove_port_data(struct port *port)

/* Remove buffers we queued up for the Host to send us data in. */
while ((buf = virtqueue_detach_unused_buf(port->in_vq)))
free_buf(buf);
free_buf(buf, true);

/* Free pending buffers from the out-queue. */
while ((buf = virtqueue_detach_unused_buf(port->out_vq)))
free_buf(buf);
free_buf(buf, true);
}

/*
Expand Down Expand Up @@ -1621,7 +1728,7 @@ static void control_work_handler(struct work_struct *work)
if (add_inbuf(portdev->c_ivq, buf) < 0) {
dev_warn(&portdev->vdev->dev,
"Error adding buffer to queue\n");
free_buf(buf);
free_buf(buf, false);
}
}
spin_unlock(&portdev->cvq_lock);
Expand Down Expand Up @@ -1817,10 +1924,10 @@ static void remove_controlq_data(struct ports_device *portdev)
return;

while ((buf = virtqueue_get_buf(portdev->c_ivq, &len)))
free_buf(buf);
free_buf(buf, true);

while ((buf = virtqueue_detach_unused_buf(portdev->c_ivq)))
free_buf(buf);
free_buf(buf, true);
}

/*
Expand Down Expand Up @@ -1867,11 +1974,15 @@ static int __devinit virtcons_probe(struct virtio_device *vdev)

multiport = false;
portdev->config.max_nr_ports = 1;
if (virtio_config_val(vdev, VIRTIO_CONSOLE_F_MULTIPORT,
offsetof(struct virtio_console_config,
max_nr_ports),
&portdev->config.max_nr_ports) == 0)

/* Don't test MULTIPORT at all if we're rproc: not a valid feature! */
if (!is_rproc_serial(vdev) &&
virtio_config_val(vdev, VIRTIO_CONSOLE_F_MULTIPORT,
offsetof(struct virtio_console_config,
max_nr_ports),
&portdev->config.max_nr_ports) == 0) {
multiport = true;
}

err = init_vqs(portdev);
if (err < 0) {
Expand Down Expand Up @@ -1981,6 +2092,16 @@ static unsigned int features[] = {
VIRTIO_CONSOLE_F_MULTIPORT,
};

static struct virtio_device_id rproc_serial_id_table[] = {
#if IS_ENABLED(CONFIG_REMOTEPROC)
{ VIRTIO_ID_RPROC_SERIAL, VIRTIO_DEV_ANY_ID },
#endif
{ 0 },
};

static unsigned int rproc_serial_features[] = {
};

#ifdef CONFIG_PM
static int virtcons_freeze(struct virtio_device *vdev)
{
Expand Down Expand Up @@ -2065,6 +2186,20 @@ static struct virtio_driver virtio_console = {
#endif
};

/*
* virtio_rproc_serial refers to __devinit function which causes
* section mismatch warnings. So use __refdata to silence warnings.
*/
static struct virtio_driver __refdata virtio_rproc_serial = {
.feature_table = rproc_serial_features,
.feature_table_size = ARRAY_SIZE(rproc_serial_features),
.driver.name = "virtio_rproc_serial",
.driver.owner = THIS_MODULE,
.id_table = rproc_serial_id_table,
.probe = virtcons_probe,
.remove = virtcons_remove,
};

static int __init init(void)
{
int err;
Expand All @@ -2089,7 +2224,15 @@ static int __init init(void)
pr_err("Error %d registering virtio driver\n", err);
goto free;
}
err = register_virtio_driver(&virtio_rproc_serial);
if (err < 0) {
pr_err("Error %d registering virtio rproc serial driver\n",
err);
goto unregister;
}
return 0;
unregister:
unregister_virtio_driver(&virtio_console);
free:
if (pdrvdata.debugfs_dir)
debugfs_remove_recursive(pdrvdata.debugfs_dir);
Expand All @@ -2099,7 +2242,10 @@ static int __init init(void)

static void __exit fini(void)
{
reclaim_dma_bufs();

unregister_virtio_driver(&virtio_console);
unregister_virtio_driver(&virtio_rproc_serial);

class_destroy(pdrvdata.class);
if (pdrvdata.debugfs_dir)
Expand Down
1 change: 1 addition & 0 deletions include/uapi/linux/virtio_ids.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,5 +37,6 @@
#define VIRTIO_ID_RPMSG 7 /* virtio remote processor messaging */
#define VIRTIO_ID_SCSI 8 /* virtio scsi */
#define VIRTIO_ID_9P 9 /* 9p virtio console */
#define VIRTIO_ID_RPROC_SERIAL 11 /* virtio remoteproc serial link */

#endif /* _LINUX_VIRTIO_IDS_H */

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