lkml.org 
[lkml]   [2019]   [Sep]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v6 2/2] tty: add rpmsg driver
From
Date
Hi Richard,

On 9/5/19 12:50 PM, Richard Genoud wrote:
> Hi Arnaud,
>
> Le 04/09/2019 à 15:09, Arnaud Pouliquen a écrit :
>> This driver exposes a standard tty interface on top of the rpmsg
>> framework through a rpmsg service.
>>
>> This driver supports multi-instances, offering a /dev/ttyRPMSGx entry
>> per rpmsg endpoint.
>>
>> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
>> Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
>> ---
>> Documentation/serial/tty_rpmsg.rst | 45 ++++
>> drivers/tty/Kconfig | 9 +
>> drivers/tty/Makefile | 1 +
>> drivers/tty/rpmsg_tty.c | 418 +++++++++++++++++++++++++++++++++++++
>> 4 files changed, 473 insertions(+)
>> create mode 100644 Documentation/serial/tty_rpmsg.rst
>> create mode 100644 drivers/tty/rpmsg_tty.c
>>
>> diff --git a/Documentation/serial/tty_rpmsg.rst b/Documentation/serial/tty_rpmsg.rst
>> new file mode 100644
>> index 000000000000..fc1d3fba73c5
>> --- /dev/null
>> +++ b/Documentation/serial/tty_rpmsg.rst
>> @@ -0,0 +1,45 @@
>> +.. SPDX-License-Identifier: GPL-2.0
>> +
>> +=============
>> +The rpmsg TTY
>> +=============
>> +
>> +The rpmsg tty driver implements serial communication on the RPMsg bus to makes possible for user-space programs to send and receive rpmsg messages as a standard tty protocol.
>> +
>> +The remote processor can instantiate a new tty by requesting:
>> +- a "rpmsg-tty-raw" RPMsg service, for TTY raw data support without flow control
>> +- a "rpmsg-tty-ctrl" RPMSg service, for TTY support with flow control.
>> +
>> +Information related to the RPMsg and associated tty device is available in
>> +/sys/bus/rpmsg/devices/.
>> +
>> +RPMsg TTY without control
>> +---------------------
>> +
>> +The default end point associated with the "rpmsg-tty-raw" service is directly
>> +used for data exchange. No flow control is available.
>> +
>> +To be compliant with this driver, the remote firmware must create its data end point associated with the "rpmsg-tty-raw" service.
>> +
>> +RPMsg TTY with control
>> +---------------------
>> +
>> +The default end point associated with the "rpmsg-tty-ctrl" service is reserved for
>> +the control. A second endpoint must be created for data exchange.
>> +
>> +The control channel is used to transmit to the remote processor the CTS status,
>> +as well as the end point address for data transfer.
>> +
>> +To be compatible with this driver, the remote firmware must create or use its end point associated with "rpmsg-tty-ctrl" service, plus a second endpoint for the data flow.
>> +On Linux rpmsg_tty probes, the data endpoint address and the CTS (set to disable)
>> +is sent to the remote processor.
>> +The remote processor has to respect following rules:
>> +- It only transmits data when Linux remote cts is enable, otherwise message
>> + could be lost.
>> +- It can pause/resume reception by sending a control message (rely on CTS state).
>> +
>> +Control message structure:
>> +struct rpmsg_tty_ctrl {
>> + u8 cts; /* remote reception status */
>> + u16 d_ept_addr; /* data endpoint address */
>> +};
> Correct me if I'm wrong, but I think this structure should be packed,
> shouldn't it ?
> It's working ok on the STM32MP127, between M4 and A7, but the alignment
> may be not the same on another architecture ?
you are right, i have to fix this.

Thanks,
Arnaud

>
>
>
>> diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
>> index c7623f99ac0f..1046bf4aa709 100644
>> --- a/drivers/tty/Kconfig
>> +++ b/drivers/tty/Kconfig
>> @@ -454,6 +454,15 @@ config VCC
>> 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.
>> +
>> config LDISC_AUTOLOAD
>> bool "Automatically load TTY Line Disciplines"
>> default y
>> diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
>> index 020b1cd9294f..c2465e7ebc2a 100644
>> --- a/drivers/tty/Makefile
>> +++ b/drivers/tty/Makefile
>> @@ -34,5 +34,6 @@ 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 000000000000..3e4d0e1a6663
>> --- /dev/null
>> +++ b/drivers/tty/rpmsg_tty.c
>> @@ -0,0 +1,418 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) STMicroelectronics 2019 - All Rights Reserved
>> + * Authors: Arnaud Pouliquen <arnaud.pouliquen@st.com> for STMicroelectronics.
>> + */
>> +
>> +#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
>> +
>> +#define TTY_CH_NAME_RAW "rpmsg-tty-raw"
>> +#define TTY_CH_NAME_WITH_CTS "rpmsg-tty-ctrl"
>> +
>> +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_ctrl {
>> + u8 cts; /* remote reception status */
>> + u16 d_ept_addr; /* data endpoint address */
>> +};
>> +
>> +struct rpmsg_tty_port {
>> + struct tty_port port; /* TTY port data */
>> + int id; /* TTY rpmsg index */
>> + bool cts; /* remote reception status */
>> + struct rpmsg_device *rpdev; /* rpmsg device */
>> + struct rpmsg_endpoint *cs_ept; /* channel control endpoint */
>> + struct rpmsg_endpoint *d_ept; /* data endpoint */
>> + u32 data_dst; /* data destination endpoint address */
>> +};
>> +
>> +typedef void (*rpmsg_tty_rx_cb_t)(struct rpmsg_device *, void *, int, void *,
>> + u32);
>> +
>> +static int rpmsg_tty_cb(struct rpmsg_device *rpdev, void *data, int len,
>> + void *priv, u32 src)
>> +{
>> + struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev);
>> + int copied;
>> +
>> + if (src == cport->data_dst) {
>> + /* data message */
>> + if (!len)
>> + return -EINVAL;
>> + /* data message */
>> + copied = tty_insert_flip_string_fixed_flag(&cport->port, data,
>> + TTY_NORMAL, len);
>> + if (copied != len)
>> + dev_dbg(&rpdev->dev, "trunc buffer: available space is %d\n",
>> + copied);
>> + tty_flip_buffer_push(&cport->port);
>> + } else {
>> + /* control message */
>> + struct rpmsg_tty_ctrl *msg = data;
>> +
>> + if (len != sizeof(*msg))
>> + return -EINVAL;
>> +
>> + cport->data_dst = msg->d_ept_addr;
>> +
>> + /* Update remote cts state */
>> + cport->cts = msg->cts ? 1 : 0;
>> +
>> + if (cport->cts)
>> + tty_port_tty_wakeup(&cport->port);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static void rpmsg_tty_send_term_ready(struct tty_struct *tty, u8 state)
>> +{
>> + struct rpmsg_tty_port *cport = tty->driver_data;
>> + struct rpmsg_tty_ctrl m_ctrl;
>> + int ret;
>> +
>> + m_ctrl.cts = state;
>> + m_ctrl.d_ept_addr = cport->d_ept->addr;
>> +
>> + ret = rpmsg_trysend(cport->cs_ept, &m_ctrl, sizeof(m_ctrl));
>> + if (ret < 0)
>> + dev_dbg(tty->dev, "cannot send control (%d)\n", ret);
>> +};
>> +
>> +static void rpmsg_tty_throttle(struct tty_struct *tty)
>> +{
>> + struct rpmsg_tty_port *cport = tty->driver_data;
>> +
>> + /* Disable remote transmission */
>> + if (cport->cs_ept)
>> + rpmsg_tty_send_term_ready(tty, 0);
>> +};
>> +
>> +static void rpmsg_tty_unthrottle(struct tty_struct *tty)
>> +{
>> + struct rpmsg_tty_port *cport = tty->driver_data;
>> +
>> + /* Enable remote transmission */
>> + if (cport->cs_ept)
>> + rpmsg_tty_send_term_ready(tty, 1);
>> +};
>> +
>> +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;
>> + }
>> +
>> + tty->driver_data = cport;
>> +
>> + 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 u8 *buf, int len)
>> +{
>> + struct rpmsg_tty_port *cport = tty->driver_data;
>> + struct rpmsg_device *rpdev;
>> + int msg_max_size, msg_size;
>> + int ret;
>> + u8 *tmpbuf;
>> +
>> + /* If cts not set, the message is not sent*/
>> + if (!cport->cts)
>> + return 0;
>> +
>> + rpdev = cport->rpdev;
>> +
>> + dev_dbg(&rpdev->dev, "%s: send msg from tty->index = %d, len = %d\n",
>> + __func__, tty->index, len);
>> +
>> + msg_max_size = rpmsg_get_mtu(rpdev->ept);
>> +
>> + msg_size = min(len, msg_max_size);
>> + tmpbuf = kzalloc(msg_size, GFP_KERNEL);
>> + if (!tmpbuf)
>> + return -ENOMEM;
>> +
>> + memcpy(tmpbuf, buf, msg_size);
>> +
>> + /*
>> + * Try to send the message to remote processor, if failed return 0 as
>> + * no data sent
>> + */
>> + ret = rpmsg_trysendto(cport->d_ept, tmpbuf, msg_size, cport->data_dst);
>> + kfree(tmpbuf);
>> + if (ret) {
>> + dev_dbg(&rpdev->dev, "rpmsg_send failed: %d\n", ret);
>> + return 0;
>> + }
>> +
>> + return msg_size;
>> +}
>> +
>> +static int rpmsg_tty_write_room(struct tty_struct *tty)
>> +{
>> + struct rpmsg_tty_port *cport = tty->driver_data;
>> +
>> + return cport->cts ? rpmsg_get_mtu(cport->rpdev->ept) : 0;
>> +}
>> +
>> +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,
>> + .throttle = rpmsg_tty_throttle,
>> + .unthrottle = rpmsg_tty_unthrottle,
>> +};
>> +
>> +static 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_port_activate(struct tty_port *p, struct tty_struct *tty)
>> +{
>> + p->low_latency = (p->flags & ASYNC_LOW_LATENCY) ? 1 : 0;
>> +
>> + /* Allocate the buffer we use for writing data */
>> + return tty_port_alloc_xmit_buf(p);
>> +}
>> +
>> +static void rpmsg_tty_port_shutdown(struct tty_port *p)
>> +{
>> + /* Free the write buffer */
>> + tty_port_free_xmit_buf(p);
>> +}
>> +
>> +static void rpmsg_tty_dtr_rts(struct tty_port *port, int raise)
>> +{
>> + dev_dbg(port->tty->dev, "%s: dtr_rts state %d\n", __func__, raise);
>> +
>> + if (raise)
>> + rpmsg_tty_unthrottle(port->tty);
>> + else
>> + rpmsg_tty_throttle(port->tty);
>> +}
>> +
>> +static const struct tty_port_operations rpmsg_tty_port_ops = {
>> + .activate = rpmsg_tty_port_activate,
>> + .shutdown = rpmsg_tty_port_shutdown,
>> + .dtr_rts = rpmsg_tty_dtr_rts,
>> +};
>> +
>> +static int rpmsg_tty_probe(struct rpmsg_device *rpdev)
>> +{
>> + struct rpmsg_tty_port *cport;
>> + struct device *dev = &rpdev->dev;
>> + struct rpmsg_channel_info chinfo;
>> + struct device *tty_dev;
>> + int ret;
>> +
>> + cport = rpmsg_tty_alloc_cport();
>> + if (IS_ERR(cport)) {
>> + dev_err(dev, "failed to alloc tty port\n");
>> + return PTR_ERR(cport);
>> + }
>> +
>> + if (!strncmp(rpdev->id.name, TTY_CH_NAME_WITH_CTS,
>> + sizeof(TTY_CH_NAME_WITH_CTS))) {
>> + /*
>> + * the default endpoint is used for control. Create a second
>> + * endpoint for the data that would be exchanges trough control
>> + * endpoint. address of the data endpoint will be provided with
>> + * the cts state
>> + */
>> + cport->cs_ept = rpdev->ept;
>> + cport->data_dst = RPMSG_ADDR_ANY;
>> +
>> + strscpy(chinfo.name, TTY_CH_NAME_WITH_CTS, sizeof(chinfo.name));
>> + chinfo.src = RPMSG_ADDR_ANY;
>> + chinfo.dst = RPMSG_ADDR_ANY;
>> +
>> + cport->d_ept = rpmsg_create_ept(rpdev, rpmsg_tty_cb, cport,
>> + chinfo);
>> + if (!cport->d_ept) {
>> + dev_err(dev, "failed to create tty control channel\n");
>> + ret = -ENOMEM;
>> + goto err_r_cport;
>> + }
>> + dev_dbg(dev, "%s: creating data endpoint with address %#x\n",
>> + __func__, cport->d_ept->addr);
>> + } else {
>> + /*
>> + * TTY over rpmsg without CTS management the default endpoint
>> + * is use for raw data transmission.
>> + */
>> + cport->cs_ept = NULL;
>> + cport->cts = 1;
>> + cport->d_ept = rpdev->ept;
>> + cport->data_dst = rpdev->dst;
>> + }
>> +
>> + tty_port_init(&cport->port);
>> + cport->port.ops = &rpmsg_tty_port_ops;
>> +
>> + tty_dev = tty_port_register_device(&cport->port, rpmsg_tty_driver,
>> + cport->id, dev);
>> + if (IS_ERR(tty_dev)) {
>> + dev_err(dev, "failed to register tty port\n");
>> + ret = PTR_ERR(tty_dev);
>> + goto err_destroy;
>> + }
>> +
>> + cport->rpdev = rpdev;
>> +
>> + dev_set_drvdata(dev, cport);
>> +
>> + dev_dbg(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);
>> + if (cport->cs_ept)
>> + rpmsg_destroy_ept(cport->d_ept);
>> +err_r_cport:
>> + 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_dbg(&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);
>> + if (cport->cs_ept)
>> + rpmsg_destroy_ept(cport->d_ept);
>> + rpmsg_tty_release_cport(cport);
>> +}
>> +
>> +static struct rpmsg_device_id rpmsg_driver_tty_id_table[] = {
>> + { .name = TTY_CH_NAME_RAW },
>> + { .name = TTY_CH_NAME_WITH_CTS},
>> + { },
>> +};
>> +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;
>> +
>> + /* Disable unused mode by default */
>> + rpmsg_tty_driver->init_termios = tty_std_termios;
>> + rpmsg_tty_driver->init_termios.c_lflag &= ~(ECHO | ICANON);
>> + rpmsg_tty_driver->init_termios.c_oflag &= ~(OPOST | ONLCR);
>> +
>> + 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_DESCRIPTION("remote processor messaging tty driver");
>> +MODULE_LICENSE("GPL v2");
>>
>
> Best regards,
> Richard
>

\
 
 \ /
  Last update: 2019-09-05 14:27    [W:0.076 / U:0.652 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site