From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 References: <1553183239-13253-1-git-send-email-fabien.dessenne@st.com> <1553183239-13253-3-git-send-email-fabien.dessenne@st.com> In-Reply-To: <1553183239-13253-3-git-send-email-fabien.dessenne@st.com> From: xiang xiao Date: Wed, 3 Apr 2019 20:47:08 +0800 Message-ID: Subject: Re: [PATCH 2/2] tty: add rpmsg driver Content-Type: text/plain; charset="UTF-8" To: Fabien Dessenne Cc: Ohad Ben-Cohen , Bjorn Andersson , Greg Kroah-Hartman , Jiri Slaby , linux-kernel@vger.kernel.org, linux-remoteproc@vger.kernel.org, Benjamin Gaignard , Arnaud Pouliquen List-ID: On Thu, Mar 21, 2019 at 11:48 PM Fabien Dessenne 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. > Signed-off-by: Arnaud Pouliquen > Signed-off-by: Fabien Dessenne > --- > 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 for STMicroelectronics. > + * Fabien Dessenne for STMicroelectronics. > + * Derived from the imx-rpmsg and omap-rpmsg implementations. > + */ > + > +#include > +#include > +#include > +#include > +#include > + > +#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 "); > +MODULE_AUTHOR("Fabien Dessenne "); > +MODULE_DESCRIPTION("virtio remote processor messaging tty driver"); > +MODULE_LICENSE("GPL v2"); > -- > 2.7.4 >