diff options
| -rw-r--r-- | drivers/tty/Kconfig | 12 | ||||
| -rw-r--r-- | drivers/tty/Makefile | 1 | ||||
| -rw-r--r-- | drivers/tty/rpmsg_tty.c | 274 |
3 files changed, 287 insertions, 0 deletions
diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig index 23cc988c68a4..cc30ff93e2e4 100644 --- a/drivers/tty/Kconfig +++ b/drivers/tty/Kconfig @@ -368,6 +368,18 @@ config VCC source "drivers/tty/hvc/Kconfig" +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. + + To compile this driver as a module, choose M here: the module will be + called rpmsg_tty. + endif # TTY source "drivers/tty/serdev/Kconfig" diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile index a2bd75fbaaa4..07aca5184a55 100644 --- a/drivers/tty/Makefile +++ b/drivers/tty/Makefile @@ -26,5 +26,6 @@ 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..813076341ffd --- /dev/null +++ b/drivers/tty/rpmsg_tty.c @@ -0,0 +1,274 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2021 STMicroelectronics - All Rights Reserved + * + * 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" RPMsg service. + * The "rpmsg-tty" service is directly used for data exchange. No flow control is implemented yet. + */ + +#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 */ + int id; /* TTY rpmsg index */ + struct rpmsg_device *rpdev; /* rpmsg device */ +}; + +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 (!len) + return -EINVAL; + copied = tty_insert_flip_string(&cport->port, data, len); + if (copied != len) + dev_err_ratelimited(&rpdev->dev, "Trunc buffer: available space is %d\n", copied); + tty_flip_buffer_push(&cport->port); + + 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); + + 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; + + rpdev = cport->rpdev; + + msg_max_size = rpmsg_get_mtu(rpdev->ept); + if (msg_max_size < 0) + return msg_max_size; + + msg_size = min(len, msg_max_size); + + /* + * Use rpmsg_trysend instead of rpmsg_send to send the message so the caller is not + * hung until a rpmsg buffer is available. In such case rpmsg_trysend returns -ENOMEM. + */ + ret = rpmsg_trysend(rpdev->ept, (void *)buf, msg_size); + if (ret) { + dev_dbg_ratelimited(&rpdev->dev, "rpmsg_send failed: %d\n", ret); + return ret; + } + + return msg_size; +} + +static unsigned int rpmsg_tty_write_room(struct tty_struct *tty) +{ + struct rpmsg_tty_port *cport = tty->driver_data; + int size; + + size = rpmsg_get_mtu(cport->rpdev->ept); + if (size < 0) + return 0; + + return size; +} + +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, +}; + +static struct rpmsg_tty_port *rpmsg_tty_alloc_cport(void) +{ + struct rpmsg_tty_port *cport; + int err; + + 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) { + err = cport->id; + kfree(cport); + return ERR_PTR(err); + } + + 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 const struct tty_port_operations rpmsg_tty_port_ops = { }; + +static int rpmsg_tty_probe(struct rpmsg_device *rpdev) +{ + struct rpmsg_tty_port *cport; + struct device *dev = &rpdev->dev; + 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); + } + + 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); + 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); + rpmsg_tty_release_cport(cport); +} + +static struct rpmsg_device_id rpmsg_driver_tty_id_table[] = { + { .name = "rpmsg-tty" }, + { }, +}; +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: + tty_driver_kref_put(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); + tty_driver_kref_put(rpmsg_tty_driver); + idr_destroy(&tty_idr); +} + +module_init(rpmsg_tty_init); +module_exit(rpmsg_tty_exit); + +MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>"); +MODULE_DESCRIPTION("remote processor messaging tty driver"); +MODULE_LICENSE("GPL v2"); |