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Date: Fri, 5 Apr 2019 14:33:08 +0200
From: Arnaud Pouliquen <arnaud.pouliquen@...com>
To: xiang xiao <xiaoxiang781216@...il.com>
CC: Fabien Dessenne <fabien.dessenne@...com>,
Ohad Ben-Cohen <ohad@...ery.com>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jslaby@...e.com>, <linux-kernel@...r.kernel.org>,
<linux-remoteproc@...r.kernel.org>,
Benjamin Gaignard <benjamin.gaignard@...com>
Subject: Re: [PATCH 2/2] tty: add rpmsg driver
On 4/5/19 12:12 PM, xiang xiao wrote:
> On Fri, Apr 5, 2019 at 12:14 AM Arnaud Pouliquen
> <arnaud.pouliquen@...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@...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?
Nothing is missing. There is no complain as the function
rpmsg_device_match returns 0, because the chinfo->dst (that corresponds
to the remote ept address) is different.
If i well remember you have also a similar implementation of the service
on your side. Do you see any incompatibility with your implementation?
>
>> 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@...com>
>>>> Signed-off-by: Fabien Dessenne <fabien.dessenne@...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@...com> for STMicroelectronics.
>>>> + * Fabien Dessenne <fabien.dessenne@...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@...com>");
>>>> +MODULE_AUTHOR("Fabien Dessenne <fabien.dessenne@...com>");
>>>> +MODULE_DESCRIPTION("virtio remote processor messaging tty driver");
>>>> +MODULE_LICENSE("GPL v2");
>>>> --
>>>> 2.7.4
>>>>
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