| Message ID | 1567602594-2913-3-git-send-email-arnaud.pouliquen@st.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | TTY: add rpmsg tty driver | expand |
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 ? > 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
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 >
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@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");