lkml.org 
[lkml]   [2019]   [Apr]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 2/2] tty: add rpmsg driver
From
Date
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
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
>>

\
 
 \ /
  Last update: 2019-04-04 18:16    [W:0.162 / U:6.348 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site