[PATCHv3] virtio_console: Add support for remoteproc serial

From: sjur . brandeland
Date: Thu Sep 20 2012 - 12:34:47 EST

From: Sjur BrÃndeland <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.

This enables use of the exising virtio_console code in
the remoteproc framework.

Signed-off-by: Sjur BrÃndeland <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: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
---
Hi Amit,

Changes since v2: Fixes for Rustys review comments. The only
"unresolved" issue (unless I missed something) is the quirky
handling of finding device grandparent when doing dma_alloc.

[Rusty wrote:]
>OK, I'll let Amit comment on the console changes, but some minor style
>comments below.

Amit, any chance that you might find time to review this?

Note: This patch is based on v3.6 so this patch is will conflict
with "virtio: console: fix error handling in init() function".
Get back to me if you want me to rebase to another baseline.

Thanks,
Sjur

drivers/char/virtio_console.c | 185 ++++++++++++++++++++++++++++++++++------
include/linux/virtio_ids.h | 1 +
2 files changed, 158 insertions(+), 28 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index cdf2f54..4f2f74e 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -35,6 +35,8 @@
#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"

/*
@@ -323,6 +325,55 @@ static bool is_console_port(struct port *port)
return false;
}

+#if IS_ENABLED(CONFIG_REMOTEPROC)
+static bool is_rproc_serial(const struct virtio_device *vdev)
+{
+ return vdev->id.device == VIRTIO_ID_RPROC_SERIAL;
+}
+#else
+static bool is_rproc_serial(const struct virtio_device *vdev)
+{
+ return false;
+}
+#endif
+
+/* Allocate data buffer from DMA memory if requested */
+static void *alloc_databuf(struct virtio_device *vdev, size_t size, gfp_t flag)
+{
+ if (is_rproc_serial(vdev)) {
+ dma_addr_t dma_addr;
+ struct device *dev = &vdev->dev;
+ /*
+ * 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
+ */
+ dev = dev->parent ? dev->parent : dev;
+ dev = dev->parent ? dev->parent : dev;
+ return dma_alloc_coherent(dev, size, &dma_addr, flag);
+ }
+ return kmalloc(size, flag);
+}
+
+static void free_databuf(struct virtio_device *vdev, size_t size, void *vaddr)
+{
+ if (is_rproc_serial(vdev)) {
+ struct device *dev = &vdev->dev;
+ dma_addr_t dma_addr;
+
+ dev = dev->parent ? dev->parent : dev;
+ dev = dev->parent ? dev->parent : dev;
+ dma_addr = virt_to_bus(vaddr);
+ dma_free_coherent(dev, size, vaddr, dma_addr);
+ return;
+ }
+ kfree(vaddr);
+}
+
static inline bool use_multiport(struct ports_device *portdev)
{
/*
@@ -334,22 +385,24 @@ 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 void free_buf(struct virtqueue *vq, struct port_buffer *buf,
+ size_t buf_size)
{
- kfree(buf->buf);
+ free_databuf(vq->vdev, buf_size, buf->buf);
kfree(buf);
}

-static struct port_buffer *alloc_buf(size_t buf_size)
+static struct port_buffer *alloc_buf(struct virtqueue *vq, size_t buf_size)
{
struct port_buffer *buf;

buf = kmalloc(sizeof(*buf), GFP_KERNEL);
if (!buf)
goto fail;
- buf->buf = kzalloc(buf_size, GFP_KERNEL);
+ buf->buf = alloc_databuf(vq->vdev, buf_size, GFP_KERNEL);
if (!buf->buf)
goto free_buf;
+ memset(buf->buf, 0, buf_size);
buf->len = 0;
buf->offset = 0;
buf->size = buf_size;
@@ -414,7 +467,7 @@ 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(port->in_vq, buf, PAGE_SIZE);
}
port->inbuf = NULL;
buf = get_inbuf(port);
@@ -485,7 +538,7 @@ static void reclaim_consumed_buffers(struct port *port)
return;
}
while ((buf = virtqueue_get_buf(port->out_vq, &len))) {
- kfree(buf);
+ free_databuf(port->portdev->vdev, PAGE_SIZE, buf);
port->outvq_full = false;
}
}
@@ -672,6 +725,8 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
char *buf;
ssize_t ret;
bool nonblock;
+ struct virtio_device *vdev;
+ size_t buf_size;

/* Userspace could be out to fool us */
if (!count)
@@ -694,9 +749,17 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
if (!port->guest_connected)
return -ENODEV;

- count = min((size_t)(32 * 1024), count);
+ vdev = port->portdev->vdev;
+
+ if (is_rproc_serial(vdev)) {
+ count = min_t(size_t, PAGE_SIZE, count);
+ buf_size = PAGE_SIZE;
+ } else {
+ count = min_t(size_t, (32 * 1024), count);
+ buf_size = count;
+ }

- buf = kmalloc(count, GFP_KERNEL);
+ buf = alloc_databuf(vdev, buf_size, GFP_KERNEL);
if (!buf)
return -ENOMEM;

@@ -720,7 +783,7 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
goto out;

free_buf:
- kfree(buf);
+ free_databuf(vdev, buf_size, buf);
out:
return ret;
}
@@ -918,7 +981,8 @@ 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);
}

@@ -1102,7 +1166,7 @@ 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;

@@ -1110,7 +1174,7 @@ 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(vq, buf, PAGE_SIZE);
break;
}
nr_added_bufs++;
@@ -1198,10 +1262,18 @@ 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;
@@ -1234,7 +1306,7 @@ 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(port->in_vq, buf, PAGE_SIZE);
free_device:
device_destroy(pdrvdata.class, port->dev->devt);
free_cdev:
@@ -1276,7 +1348,17 @@ 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(port->in_vq, buf, PAGE_SIZE);
+
+ /*
+ * 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_databuf(port->portdev->vdev, PAGE_SIZE, buf);
+ }
}

/*
@@ -1478,7 +1560,7 @@ 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(portdev->c_ivq, buf, PAGE_SIZE);
}
}
spin_unlock(&portdev->cvq_lock);
@@ -1674,10 +1756,10 @@ static void remove_controlq_data(struct ports_device *portdev)
return;

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

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

/*
@@ -1722,13 +1804,17 @@ 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 +1924,16 @@ 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 +2018,20 @@ 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 +2051,31 @@ 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)
{
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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