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@xxxxxx> Signed-off-by: Fabien Dessenne <fabien.dessenne@xxxxxx> --- 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 */ +}; 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@xxxxxx> 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@xxxxxx>"); +MODULE_DESCRIPTION("remote processor messaging tty driver"); +MODULE_LICENSE("GPL v2"); -- 2.7.4