From: Sjur Brændeland <sjur.brandeland@xxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxx>
cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
cc: Amit Shah <amit.shah@xxxxxxxxxx>
cc: Ohad Ben-Cohen <ohad@xxxxxxxxxx>
cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
cc: Arnd Bergmann <arnd@xxxxxxxx>
---
Changes since v3 are mostly related to freeing of dma-buffers:
- Change port_fops_write() to use struct port_buffer when allocating
memory. This is done in order to store the dma-address of the
allocated buffers, so the correct dma-address can be passed to
dma_free_coherent().
- Added pending_free_list for port_buf. dma_free_coherent() requires
the irqs to be enabled, so if irqs are disabled we queue the buffer
on the pending_free_list and free it later when irqs are enabled.
- Remove #if around is_rproc_serial
Thanks,
Sjur
drivers/char/virtio_console.c | 222 ++++++++++++++++++++++++++++++++++++-----
include/linux/virtio_ids.h | 1 +
2 files changed, 199 insertions(+), 24 deletions(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index cdf2f54..3af9a5d 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -35,8 +35,12 @@
#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 rproc_enabled IS_ENABLED(CONFIG_REMOTEPROC)
+
/*
* This is a global struct for storing common data for all the devices
* this driver handles.
@@ -109,6 +113,15 @@ struct port_buffer {
size_t len;
/* 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;
};
/*
@@ -323,6 +336,11 @@ static bool is_console_port(struct port *port)
return false;
}
+static bool is_rproc_serial(const struct virtio_device *vdev)
+{
+ return rproc_enabled && vdev->id.device == VIRTIO_ID_RPROC_SERIAL;
+}
+
static inline bool use_multiport(struct ports_device *portdev)
{
/*
@@ -334,20 +352,99 @@ static inline bool use_multiport(struct ports_device *portdev)
return portdev->vdev->features[0] & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
}
+static DEFINE_SPINLOCK(list_lock);
+static LIST_HEAD(pending_free_list);
+
static void free_buf(struct port_buffer *buf)
{
- kfree(buf->buf);
+ unsigned long flags;
+
+ if (!buf->dev) {
+ kfree(buf->buf);
+ goto freebuf;
+ }
+
+ BUG_ON(!rproc_enabled);
+
+ /* dma_free_coherent requires interrupts to be enabled */
+ if (rproc_enabled && !irqs_disabled()) {
+ dma_free_coherent(buf->dev, buf->size, buf->buf, buf->dma);
+
+ /* Release device refcnt and allow it to be freed */
+ might_sleep();
+ put_device(buf->dev);
+ goto freebuf;
+ }
+
+ /* queue up dma-buffers to be freed later */
+ spin_lock_irqsave(&list_lock, flags);
+ list_add_tail(&buf->list, &pending_free_list);
+ spin_unlock_irqrestore(&list_lock, flags);
+ return;
+
+freebuf:
kfree(buf);
}
-static struct port_buffer *alloc_buf(size_t buf_size)
+static void reclaim_dma_bufs(void)
+{
+ unsigned long flags;
+ struct port_buffer *buf, *tmp;
+ LIST_HEAD(tmp_list);
+
+ WARN_ON(irqs_disabled());
+ if (list_empty(&pending_free_list))
+ return;
+
+ BUG_ON(!rproc_enabled);
+
+ /* Create a copy of the pending_free_list while holding the lock*/
+ spin_lock_irqsave(&list_lock, flags);
+ list_cut_position(&tmp_list, &pending_free_list,
+ pending_free_list.prev);
+ spin_unlock_irqrestore(&list_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);
+ }
+}
+
+static struct port_buffer *alloc_buf(struct virtqueue *vq, size_t buf_size)
{
struct port_buffer *buf;
+ if (is_rproc_serial(vq->vdev) && !irqs_disabled())
+ reclaim_dma_bufs();
+
buf = kmalloc(sizeof(*buf), GFP_KERNEL);
if (!buf)
goto fail;
- buf->buf = kzalloc(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->buf = kmalloc(buf_size, GFP_KERNEL);
+ buf->dev = NULL;
+ }
+
if (!buf->buf)
goto free_buf;
buf->len = 0;
@@ -485,7 +582,10 @@ static void reclaim_consumed_buffers(struct port *port)
return;
}
while ((buf = virtqueue_get_buf(port->out_vq, &len))) {
- kfree(buf);
+ if (is_console_port(port))
+ kfree(buf);
+ else
+ free_buf(buf);
port->outvq_full = false;
}
}
@@ -498,6 +598,7 @@ static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count,
ssize_t ret;
unsigned long flags;
unsigned int len;
+ struct port_buffer *buf = in_buf;
out_vq = port->out_vq;
@@ -505,8 +606,11 @@ static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count,
reclaim_consumed_buffers(port);
- sg_init_one(sg, in_buf, in_count);
- ret = virtqueue_add_buf(out_vq, sg, 1, 0, in_buf, GFP_ATOMIC);
+ if (is_console_port(port))
+ sg_init_one(sg, in_buf, in_count);
+ else
+ sg_init_one(sg, buf->buf, in_count);
+ ret = virtqueue_add_buf(out_vq, sg, 1, 0, buf, GFP_ATOMIC);
/* Tell Host to go! */
virtqueue_kick(out_vq);
@@ -669,7 +773,7 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
size_t count, loff_t *offp)
{
struct port *port;
- char *buf;
+ struct port_buffer *buf;
ssize_t ret;
bool nonblock;
@@ -696,11 +800,11 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
count = min((size_t)(32 * 1024), count);
- buf = kmalloc(count, GFP_KERNEL);
+ buf = alloc_buf(port->out_vq, count);
if (!buf)
return -ENOMEM;
- ret = copy_from_user(buf, ubuf, count);
+ ret = copy_from_user(buf->buf, ubuf, count);
if (ret) {
ret = -EFAULT;
goto free_buf;
@@ -720,7 +824,7 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
goto out;
free_buf:
- kfree(buf);
+ free_buf(buf);
out:
return ret;
}
@@ -770,6 +874,8 @@ static int port_fops_release(struct inode *inode, struct file *filp)
reclaim_consumed_buffers(port);
spin_unlock_irq(&port->outvq_lock);
+ if (is_rproc_serial(port->portdev->vdev) && !irqs_disabled())
+ 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
@@ -918,7 +1024,8 @@ static void resize_console(struct port *port)
return;
vdev = port->portdev->vdev;
- if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_SIZE))
+ if (!is_rproc_serial(vdev) &&
+ virtio_has_feature(vdev, VIRTIO_CONSOLE_F_SIZE))
hvc_resize(port->cons.hvc, port->cons.ws);
}
@@ -1102,10 +1209,10 @@ static unsigned int fill_queue(struct virtqueue *vq, spinlock_t *lock)
nr_added_bufs = 0;
do {
- buf = alloc_buf(PAGE_SIZE);
+ buf = alloc_buf(vq, PAGE_SIZE);
if (!buf)
break;
-
+ memset(buf->buf, 0, PAGE_SIZE);
spin_lock_irq(lock);
ret = add_inbuf(vq, buf);
if (ret < 0) {
@@ -1198,10 +1305,18 @@ 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, but
+ * 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;
@@ -1277,6 +1392,16 @@ 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);
+
+ /*
+ * Remove buffers from out queue for rproc-serial. We cannot afford
+ * to leak any DMA mem, so reclaim this memory even if this might be
+ * racy for the remote processor.
+ */
+ if (is_rproc_serial(port->portdev->vdev)) {
+ while ((buf = virtqueue_detach_unused_buf(port->out_vq)))
+ free_buf(buf);
+ }
}
/*
@@ -1722,13 +1847,17 @@ static int __devinit virtcons_probe(struct virtio_device *vdev)
goto free;
}
- 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;
+ } else {
+ multiport = false;
+ portdev->config.max_nr_ports = 1;
+ }
err = init_vqs(portdev);
if (err < 0) {
@@ -1838,6 +1967,16 @@ 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)
{
@@ -1922,6 +2061,20 @@ 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;
@@ -1941,12 +2094,33 @@ static int __init init(void)
INIT_LIST_HEAD(&pdrvdata.consoles);
INIT_LIST_HEAD(&pdrvdata.portdevs);
- return register_virtio_driver(&virtio_console);
+ err = register_virtio_driver(&virtio_console);
+ if (err < 0) {
+ 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);
+ class_destroy(pdrvdata.class);
+ return err;
}
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)
diff --git a/include/linux/virtio_ids.h b/include/linux/virtio_ids.h
index 270fb22..cb28b52 100644
--- a/include/linux/virtio_ids.h
+++ b/include/linux/virtio_ids.h
@@ -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 */
--
1.7.5.4
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