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. Signed-off-by: Arnaud Pouliquen <[email protected]> Signed-off-by: Fabien Dessenne <[email protected]> --- 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 <[email protected]> for STMicroelectronics. + * Fabien Dessenne <[email protected]> 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); + + 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 <[email protected]>"); +MODULE_AUTHOR("Fabien Dessenne <[email protected]>"); +MODULE_DESCRIPTION("virtio remote processor messaging tty driver"); +MODULE_LICENSE("GPL v2"); -- 2.7.4
