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SubjectRe: [PATCH 2/2] tty: add rpmsg driver
On Fri, Apr 5, 2019 at 12:14 AM Arnaud Pouliquen
<arnaud.pouliquen@st.com> wrote:
>
> Hello Xiang,
>
>
> On 4/3/19 2:47 PM, xiang xiao wrote:
> > On Thu, Mar 21, 2019 at 11:48 PM Fabien Dessenne <fabien.dessenne@st.com> wrote:
> >>
> >> This driver exposes a standard tty interface on top of the rpmsg
> >> framework through the "rpmsg-tty-channel" rpmsg service.
> >>
> >> This driver supports multi-instances, offering a /dev/ttyRPMSGx entry
> >> per rpmsg endpoint.
> >>
> >
> > How to support multi-instances from the same remoteproc instance? I
> > saw that the channel name is fixed to "rpmsg-tty-channel" which mean
> > only one channel can be created for each remote side.
> The driver is multi-instance based on muti-endpoints on top of the
> "rpmsg-tty-channel" service.
> On remote side you just have to call rpmsg_create_ept with destination
> address set to ANY. The result is a NS service announcement that trigs a
> probe with a new endpoint.
> You can find code example for the remote side here:
> https://github.com/STMicroelectronics/STM32CubeMP1/blob/master/Projects/STM32MP157C-DK2/Applications/OpenAMP/OpenAMP_TTY_echo/Src/main.c

Demo code create two uarts(huart0 and huart1), and both use the same
channel name( "rpmsg-tty-channel").
But rpmsg_create_channel in kernel will complain the duplication:
/* make sure a similar channel doesn't already exist */
tmp = rpmsg_find_device(dev, chinfo);
if (tmp) {
/* decrement the matched device's refcount back */
put_device(tmp);
dev_err(dev, "channel %s:%x:%x already exist\n",
chinfo->name, chinfo->src, chinfo->dst);
return NULL;
}
Do you have some local change not upstream yet?

> using some wrapper functions available here:
> https://github.com/STMicroelectronics/STM32CubeMP1/tree/master/Middlewares/Third_Party/OpenAMP
>
>
> Best Regards
> Arnaud
>
> >
> >> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
> >> Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
> >> ---
> >> drivers/tty/Kconfig | 9 ++
> >> drivers/tty/Makefile | 1 +
> >> drivers/tty/rpmsg_tty.c | 309 ++++++++++++++++++++++++++++++++++++++++++++++++
> >> 3 files changed, 319 insertions(+)
> >> create mode 100644 drivers/tty/rpmsg_tty.c
> >>
> >> diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
> >> index 0840d27..42696e6 100644
> >> --- a/drivers/tty/Kconfig
> >> +++ b/drivers/tty/Kconfig
> >> @@ -441,4 +441,13 @@ config VCC
> >> depends on SUN_LDOMS
> >> help
> >> Support for Sun logical domain consoles.
> >> +
> >> +config RPMSG_TTY
> >> + tristate "RPMSG tty driver"
> >> + depends on RPMSG
> >> + help
> >> + Say y here to export rpmsg endpoints as tty devices, usually found
> >> + in /dev/ttyRPMSGx.
> >> + This makes it possible for user-space programs to send and receive
> >> + rpmsg messages as a standard tty protocol.
> >> endif # TTY
> >> diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
> >> index c72cafd..90a98a2 100644
> >> --- a/drivers/tty/Makefile
> >> +++ b/drivers/tty/Makefile
> >> @@ -33,5 +33,6 @@ obj-$(CONFIG_PPC_EPAPR_HV_BYTECHAN) += ehv_bytechan.o
> >> obj-$(CONFIG_GOLDFISH_TTY) += goldfish.o
> >> obj-$(CONFIG_MIPS_EJTAG_FDC_TTY) += mips_ejtag_fdc.o
> >> obj-$(CONFIG_VCC) += vcc.o
> >> +obj-$(CONFIG_RPMSG_TTY) += rpmsg_tty.o
> >>
> >> obj-y += ipwireless/
> >> diff --git a/drivers/tty/rpmsg_tty.c b/drivers/tty/rpmsg_tty.c
> >> new file mode 100644
> >> index 0000000..9c2a629
> >> --- /dev/null
> >> +++ b/drivers/tty/rpmsg_tty.c
> >> @@ -0,0 +1,309 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * Copyright (C) STMicroelectronics 2019 - All Rights Reserved
> >> + * Authors: Arnaud Pouliquen <arnaud.pouliquen@st.com> for STMicroelectronics.
> >> + * Fabien Dessenne <fabien.dessenne@st.com> for STMicroelectronics.
> >> + * Derived from the imx-rpmsg and omap-rpmsg implementations.
> >> + */
> >> +
> >> +#include <linux/module.h>
> >> +#include <linux/rpmsg.h>
> >> +#include <linux/slab.h>
> >> +#include <linux/tty.h>
> >> +#include <linux/tty_flip.h>
> >> +
> >> +#define MAX_TTY_RPMSG 32
> >> +
> >> +static DEFINE_IDR(tty_idr); /* tty instance id */
> >> +static DEFINE_MUTEX(idr_lock); /* protects tty_idr */
> >> +
> >> +static struct tty_driver *rpmsg_tty_driver;
> >> +
> >> +struct rpmsg_tty_port {
> >> + struct tty_port port; /* TTY port data */
> >> + unsigned int id; /* TTY rpmsg index */
> >> + spinlock_t rx_lock; /* message reception lock */
> >> + struct rpmsg_device *rpdev; /* rpmsg device */
> >> +};
> >> +
> >> +static int rpmsg_tty_cb(struct rpmsg_device *rpdev, void *data, int len,
> >> + void *priv, u32 src)
> >> +{
> >> + int space;
> >> + unsigned char *cbuf;
> >> + struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev);
> >> +
> >> + dev_dbg(&rpdev->dev, "msg(<- src 0x%x) len %d\n", src, len);
> >> +
> >> + print_hex_dump_debug(__func__, DUMP_PREFIX_NONE, 16, 1, data, len,
> >> + true);
> >> +
> >> + /* Flush the recv-ed none-zero data to tty node */
> >> + if (!len)
> >> + return -EINVAL;
> >> +
> >> + spin_lock(&cport->rx_lock);
> >> + space = tty_prepare_flip_string(&cport->port, &cbuf, len);
> >> + if (space <= 0) {
> >> + dev_err(&rpdev->dev, "No memory for tty_prepare_flip_string\n");
> >> + spin_unlock(&cport->rx_lock);
> >> + return -ENOMEM;
> >> + }
> >> +
> >> + if (space != len)
> >> + dev_warn(&rpdev->dev, "Trunc buffer from %d to %d\n",
> >> + len, space);
> >> +
> >> + memcpy(cbuf, data, space);
> >> + tty_flip_buffer_push(&cport->port);
> >> + spin_unlock(&cport->rx_lock);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +static int rpmsg_tty_install(struct tty_driver *driver, struct tty_struct *tty)
> >> +{
> >> + struct rpmsg_tty_port *cport = idr_find(&tty_idr, tty->index);
> >> +
> >> + if (!cport) {
> >> + dev_err(tty->dev, "cannot get cport\n");
> >> + return -ENODEV;
> >> + }
> >> +
> >> + return tty_port_install(&cport->port, driver, tty);
> >> +}
> >> +
> >> +static int rpmsg_tty_open(struct tty_struct *tty, struct file *filp)
> >> +{
> >> + return tty_port_open(tty->port, tty, filp);
> >> +}
> >> +
> >> +static void rpmsg_tty_close(struct tty_struct *tty, struct file *filp)
> >> +{
> >> + return tty_port_close(tty->port, tty, filp);
> >> +}
> >> +
> >> +static int rpmsg_tty_write(struct tty_struct *tty, const unsigned char *buf,
> >> + int total)
> >> +{
> >> + int count, ret = 0;
> >> + const unsigned char *tbuf;
> >> + struct rpmsg_tty_port *cport = idr_find(&tty_idr, tty->index);
> >> + struct rpmsg_device *rpdev;
> >> + int msg_size;
> >> +
> >> + if (!cport) {
> >> + dev_err(tty->dev, "cannot get cport\n");
> >> + return -ENODEV;
> >> + }
> >> +
> >> + rpdev = cport->rpdev;
> >> +
> >> + dev_dbg(&rpdev->dev, "%s: send message from tty->index = %d\n",
> >> + __func__, tty->index);
> >> +
> >> + if (!buf) {
> >> + dev_err(&rpdev->dev, "buf shouldn't be null.\n");
> >> + return -ENOMEM;
> >> + }
> >> +
> >> + msg_size = rpmsg_get_buf_payload_size(rpdev->ept);
> >> + if (msg_size < 0)
> >> + return msg_size;
> >> +
> >> + count = total;
> >> + tbuf = buf;
> >> + do {
> >> + /* send a message to our remote processor */
> >> + ret = rpmsg_send(rpdev->ept, (void *)tbuf,
> >> + min(count, msg_size));
> >> + if (ret) {
> >> + dev_err(&rpdev->dev, "rpmsg_send failed: %d\n", ret);
> >> + return ret;
> >> + }
> >> +
> >> + if (count > msg_size) {
> >> + count -= msg_size;
> >> + tbuf += msg_size;
> >> + } else {
> >> + count = 0;
> >> + }
> >> + } while (count > 0);
> >> +
> > We need the flow control(or handshake) here, otherwise it's very easy
> > to lose the data if kernel keep send the data as fast as possible.
> >
> >> + return total;
> >> +}
> >> +
> >> +static int rpmsg_tty_write_room(struct tty_struct *tty)
> >> +{
> >> + struct rpmsg_tty_port *cport = idr_find(&tty_idr, tty->index);
> >> +
> >> + if (!cport) {
> >> + dev_err(tty->dev, "cannot get cport\n");
> >> + return -ENODEV;
> >> + }
> >> +
> >> + /* report the space in the rpmsg buffer */
> >> + return rpmsg_get_buf_payload_size(cport->rpdev->ept);
> >> +}
> >> +
> >> +static const struct tty_operations rpmsg_tty_ops = {
> >> + .install = rpmsg_tty_install,
> >> + .open = rpmsg_tty_open,
> >> + .close = rpmsg_tty_close,
> >> + .write = rpmsg_tty_write,
> >> + .write_room = rpmsg_tty_write_room,
> >> +};
> >> +
> >> +struct rpmsg_tty_port *rpmsg_tty_alloc_cport(void)
> >> +{
> >> + struct rpmsg_tty_port *cport;
> >> +
> >> + cport = kzalloc(sizeof(*cport), GFP_KERNEL);
> >> + if (!cport)
> >> + return ERR_PTR(-ENOMEM);
> >> +
> >> + mutex_lock(&idr_lock);
> >> + cport->id = idr_alloc(&tty_idr, cport, 0, MAX_TTY_RPMSG, GFP_KERNEL);
> >> + mutex_unlock(&idr_lock);
> >> +
> >> + if (cport->id < 0) {
> >> + kfree(cport);
> >> + return ERR_PTR(-ENOSPC);
> >> + }
> >> +
> >> + return cport;
> >> +}
> >> +
> >> +static void rpmsg_tty_release_cport(struct rpmsg_tty_port *cport)
> >> +{
> >> + mutex_lock(&idr_lock);
> >> + idr_remove(&tty_idr, cport->id);
> >> + mutex_unlock(&idr_lock);
> >> +
> >> + kfree(cport);
> >> +}
> >> +
> >> +static int rpmsg_tty_probe(struct rpmsg_device *rpdev)
> >> +{
> >> + struct rpmsg_tty_port *cport;
> >> + struct device *tty_dev;
> >> + int ret;
> >> +
> >> + cport = rpmsg_tty_alloc_cport();
> >> + if (IS_ERR(cport)) {
> >> + dev_err(&rpdev->dev, "failed to alloc tty port\n");
> >> + return PTR_ERR(cport);
> >> + }
> >> +
> >> + tty_port_init(&cport->port);
> >> + cport->port.low_latency = cport->port.flags | ASYNC_LOW_LATENCY;
> >> +
> >> + tty_dev = tty_port_register_device(&cport->port, rpmsg_tty_driver,
> >> + cport->id, &rpdev->dev);
> >> + if (IS_ERR(tty_dev)) {
> >> + dev_err(&rpdev->dev, "failed to register tty port\n");
> >> + ret = PTR_ERR(tty_dev);
> >> + goto err_destroy;
> >> + }
> >> +
> >> + spin_lock_init(&cport->rx_lock);
> >> + cport->rpdev = rpdev;
> >> +
> >> + dev_set_drvdata(&rpdev->dev, cport);
> >> +
> >> + dev_info(&rpdev->dev, "new channel: 0x%x -> 0x%x : ttyRPMSG%d\n",
> >> + rpdev->src, rpdev->dst, cport->id);
> >> +
> >> + return 0;
> >> +
> >> +err_destroy:
> >> + tty_port_destroy(&cport->port);
> >> + rpmsg_tty_release_cport(cport);
> >> + return ret;
> >> +}
> >> +
> >> +static void rpmsg_tty_remove(struct rpmsg_device *rpdev)
> >> +{
> >> + struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev);
> >> +
> >> + dev_info(&rpdev->dev, "removing rpmsg tty device %d\n", cport->id);
> >> +
> >> + /* User hang up to release the tty */
> >> + if (tty_port_initialized(&cport->port))
> >> + tty_port_tty_hangup(&cport->port, false);
> >> +
> >> + tty_unregister_device(rpmsg_tty_driver, cport->id);
> >> + tty_port_destroy(&cport->port);
> >> +
> >> + rpmsg_tty_release_cport(cport);
> >> +}
> >> +
> >> +static struct rpmsg_device_id rpmsg_driver_tty_id_table[] = {
> >> + { .name = "rpmsg-tty-channel" },
> >> + { },
> >> +};
> >> +MODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_tty_id_table);
> >> +
> >> +static struct rpmsg_driver rpmsg_tty_rpmsg_drv = {
> >> + .drv.name = KBUILD_MODNAME,
> >> + .id_table = rpmsg_driver_tty_id_table,
> >> + .probe = rpmsg_tty_probe,
> >> + .callback = rpmsg_tty_cb,
> >> + .remove = rpmsg_tty_remove,
> >> +};
> >> +
> >> +static int __init rpmsg_tty_init(void)
> >> +{
> >> + int err;
> >> +
> >> + rpmsg_tty_driver = tty_alloc_driver(MAX_TTY_RPMSG, TTY_DRIVER_REAL_RAW |
> >> + TTY_DRIVER_DYNAMIC_DEV);
> >> + if (IS_ERR(rpmsg_tty_driver))
> >> + return PTR_ERR(rpmsg_tty_driver);
> >> +
> >> + rpmsg_tty_driver->driver_name = "rpmsg_tty";
> >> + rpmsg_tty_driver->name = "ttyRPMSG";
> >> + rpmsg_tty_driver->major = 0;
> >> + rpmsg_tty_driver->type = TTY_DRIVER_TYPE_CONSOLE;
> >> + rpmsg_tty_driver->init_termios = tty_std_termios;
> >> +
> >> + tty_set_operations(rpmsg_tty_driver, &rpmsg_tty_ops);
> >> +
> >> + err = tty_register_driver(rpmsg_tty_driver);
> >> + if (err < 0) {
> >> + pr_err("Couldn't install rpmsg tty driver: err %d\n", err);
> >> + goto error_put;
> >> + }
> >> +
> >> + err = register_rpmsg_driver(&rpmsg_tty_rpmsg_drv);
> >> + if (err < 0) {
> >> + pr_err("Couldn't register rpmsg tty driver: err %d\n", err);
> >> + goto error_unregister;
> >> + }
> >> +
> >> + return 0;
> >> +
> >> +error_unregister:
> >> + tty_unregister_driver(rpmsg_tty_driver);
> >> +
> >> +error_put:
> >> + put_tty_driver(rpmsg_tty_driver);
> >> +
> >> + return err;
> >> +}
> >> +
> >> +static void __exit rpmsg_tty_exit(void)
> >> +{
> >> + unregister_rpmsg_driver(&rpmsg_tty_rpmsg_drv);
> >> + tty_unregister_driver(rpmsg_tty_driver);
> >> + put_tty_driver(rpmsg_tty_driver);
> >> + idr_destroy(&tty_idr);
> >> +}
> >> +
> >> +module_init(rpmsg_tty_init);
> >> +module_exit(rpmsg_tty_exit);
> >> +
> >> +MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@st.com>");
> >> +MODULE_AUTHOR("Fabien Dessenne <fabien.dessenne@st.com>");
> >> +MODULE_DESCRIPTION("virtio remote processor messaging tty driver");
> >> +MODULE_LICENSE("GPL v2");
> >> --
> >> 2.7.4
> >>

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