| Message ID | 20231130224408.3591288-8-Frank.Li@nxp.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | i3c: master: some improvment for i3c master | expand |
Hi Frank, Frank.Li@nxp.com wrote on Thu, 30 Nov 2023 17:44:08 -0500: > In typical embedded Linux systems, UART consoles require at least two pins, > TX and RX. In scenarios where I2C/I3C devices like sensors or PMICs are > present, we can save these two pins by using this driver. Pins is crucial > resources, especially in small chip packages. > > This introduces support for using the I3C bus to transfer console tty data, > effectively replacing the need for dedicated UART pins. This not only > conserves valuable pin resources but also facilitates testing of I3C's > advanced features, including early termination, in-band interrupt (IBI) > support, and the creation of more complex data patterns. Additionally, > it aids in identifying and addressing issues within the I3C controller > driver. > > Signed-off-by: Frank Li <Frank.Li@nxp.com> > --- > > Notes: > Change from v4 to v5 > - send in i3c improvememtn patches. This is not what I said, I believe this patch and the previous patch should be sent separately. Thanks, Miquèl
On 30. 11. 23, 23:44, Frank Li wrote: > In typical embedded Linux systems, UART consoles require at least two pins, > TX and RX. In scenarios where I2C/I3C devices like sensors or PMICs are > present, we can save these two pins by using this driver. Pins is crucial > resources, especially in small chip packages. > > This introduces support for using the I3C bus to transfer console tty data, > effectively replacing the need for dedicated UART pins. This not only > conserves valuable pin resources but also facilitates testing of I3C's > advanced features, including early termination, in-band interrupt (IBI) > support, and the creation of more complex data patterns. Additionally, > it aids in identifying and addressing issues within the I3C controller > driver. > > Signed-off-by: Frank Li <Frank.Li@nxp.com> ... > --- a/drivers/tty/Kconfig > +++ b/drivers/tty/Kconfig > @@ -412,6 +412,19 @@ config RPMSG_TTY > To compile this driver as a module, choose M here: the module will be > called rpmsg_tty. > > +config I3C_TTY > + tristate "TTY over I3C" > + depends on I3C > + help > + Select this options if you'd like use TTY over I3C master controller this option to use add a period to the end. > + > + This makes it possible for user-space programs to send and receive > + data as a standard tty protocol. I3C provide relatively higher data > + transfer rate and less pin numbers, SDA/SCL are shared with other > + devices. > + > + If unsure, say N > + > endif # TTY > > source "drivers/tty/serdev/Kconfig" ... > --- /dev/null > +++ b/drivers/tty/i3c_tty.c > @@ -0,0 +1,443 @@ ... > +struct ttyi3c_port { > + struct tty_port port; > + int minor; > + spinlock_t xlock; /* protect xmit */ > + char tx_buff[I3C_TTY_TRANS_SIZE]; > + char rx_buff[I3C_TTY_TRANS_SIZE]; These should be u8 as per the other changes throughout the tty layer. > + struct i3c_device *i3cdev; > + struct work_struct txwork; > + struct work_struct rxwork; > + struct completion txcomplete; > + unsigned long status; > + int buf_overrun; Can this be ever negative? > +}; > + > +struct workqueue_struct *workqueue; Is this related: Still below items not be fixed (according to Jiri Slaby's comments) - rxwork thread: need trigger from two position. - common thread queue: need some suggestion ? As I don't remember, could you elaborate again why you need your own workqueue? You need to do it in the commit log anyway. ... > +static ssize_t i3c_write(struct tty_struct *tty, const unsigned char *buf, size_t count) > +{ > + struct ttyi3c_port *sport = tty->driver_data; > + unsigned long flags; > + bool is_empty; > + int ret; > + > + spin_lock_irqsave(&sport->xlock, flags); > + ret = kfifo_in(&sport->port.xmit_fifo, buf, count); > + is_empty = kfifo_is_empty(&sport->port.xmit_fifo); > + spin_unlock_irqrestore(&sport->xlock, flags); > + > + if (!is_empty) > + queue_work(workqueue, &sport->txwork); > + > + return ret; > +} > + > +static int i3c_put_char(struct tty_struct *tty, unsigned char ch) > +{ > + struct ttyi3c_port *sport = tty->driver_data; > + unsigned long flags; > + int ret = 0; Unneeded initialization. > + > + spin_lock_irqsave(&sport->xlock, flags); > + ret = kfifo_put(&sport->port.xmit_fifo, ch); > + spin_unlock_irqrestore(&sport->xlock, flags); > + > + return ret; > +} ... > +static void tty_i3c_rxwork(struct work_struct *work) > +{ > + struct ttyi3c_port *sport = container_of(work, struct ttyi3c_port, rxwork); > + struct i3c_priv_xfer xfers; > + int retry = I3C_TTY_RETRY; Likely, should be unsigned. > + u16 status = BIT(0); > + int ret; > + > + memset(&xfers, 0, sizeof(xfers)); > + xfers.data.in = sport->rx_buff; > + xfers.len = I3C_TTY_TRANS_SIZE; > + xfers.rnw = 1; > + > + do { > + if (test_bit(I3C_TTY_RX_STOP, &sport->status)) > + break; > + > + i3c_device_do_priv_xfers(sport->i3cdev, &xfers, 1); > + > + if (xfers.actual_len) { > + ret = tty_insert_flip_string(&sport->port, sport->rx_buff, > + xfers.actual_len); > + if (ret < xfers.actual_len) > + sport->buf_overrun++; > + > + retry = I3C_TTY_RETRY; > + continue; > + } > + > + status = BIT(0); > + i3c_device_getstatus_format1(sport->i3cdev, &status); > + /* > + * Target side needs some time to fill data into fifo. Target side may not > + * have hardware update status in real time. Software update status always > + * needs some delays. > + * > + * Generally, target side have circular buffer in memory, it will be moved > + * into FIFO by CPU or DMA. 'status' just show if circular buffer empty. But > + * there are gap, especially CPU have not response irq to fill FIFO in time. > + * So xfers.actual will be zero, wait for little time to avoid flood > + * transfer in i3c bus. > + */ > + usleep_range(I3C_TTY_YIELD_US, 10 * I3C_TTY_YIELD_US); > + retry--; > + > + } while (retry && (status & BIT(0))); > + > + tty_flip_buffer_push(&sport->port); > +} > + > +static void tty_i3c_txwork(struct work_struct *work) > +{ > + struct ttyi3c_port *sport = container_of(work, struct ttyi3c_port, txwork); > + struct i3c_priv_xfer xfers; > + int retry = I3C_TTY_RETRY; Detto. > + unsigned long flags; > + int ret; > + > + xfers.rnw = 0; > + xfers.data.out = sport->tx_buff; > + > + while (!kfifo_is_empty(&sport->port.xmit_fifo) && retry) { > + xfers.len = kfifo_len(&sport->port.xmit_fifo); > + xfers.len = min_t(u16, I3C_TTY_TRANS_SIZE, xfers.len); > + > + xfers.len = kfifo_out_peek(&sport->port.xmit_fifo, sport->tx_buff, xfers.len); Can this simply be: xfers.len = kfifo_out_peek(&sport->port.xmit_fifo, sport->tx_buff, I3C_TTY_TRANS_SIZE); ? > + > + ret = i3c_device_do_priv_xfers(sport->i3cdev, &xfers, 1); > + if (ret) { > + /* > + * Target side may not move data out of FIFO. delay can't resolve problem, > + * just reduce some possiblity. Target can't end I3C SDR mode write > + * transfer, discard data is reasonable when FIFO overrun. > + */ > + usleep_range(I3C_TTY_YIELD_US, 10 * I3C_TTY_YIELD_US); > + retry--; > + } else { > + retry = I3C_TTY_RETRY; > + ret = kfifo_out(&sport->port.xmit_fifo, sport->tx_buff, xfers.len); Just to make sure: xfers.len is nor overwritten by i3c_device_do_priv_xfers(), right? > + } > + } > + > + spin_lock_irqsave(&sport->xlock, flags); Why do you take the lock here, but not during the kfifo operations above? > + if (kfifo_is_empty(&sport->port.xmit_fifo)) > + complete(&sport->txcomplete); > + spin_unlock_irqrestore(&sport->xlock, flags); > +} > +static int __init i3c_tty_init(void) > +{ > + int ret; > + > + i3c_tty_driver = tty_alloc_driver(I3C_TTY_MINORS, > + TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV); > + > + if (IS_ERR(i3c_tty_driver)) > + return PTR_ERR(i3c_tty_driver); > + > + i3c_tty_driver->driver_name = "ttyI3C"; > + i3c_tty_driver->name = "ttyI3C"; > + i3c_tty_driver->minor_start = 0, > + i3c_tty_driver->type = TTY_DRIVER_TYPE_SERIAL, > + i3c_tty_driver->subtype = SERIAL_TYPE_NORMAL, > + i3c_tty_driver->init_termios = tty_std_termios; > + i3c_tty_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | > + CLOCAL; > + i3c_tty_driver->init_termios.c_lflag = 0; > + > + tty_set_operations(i3c_tty_driver, &i3c_tty_ops); > + > + ret = tty_register_driver(i3c_tty_driver); > + if (ret) > + goto err_tty_register_driver; > + > + ret = i3c_driver_register(&i3c_driver); > + if (ret) > + goto err_i3c_driver_register; > + > + workqueue = alloc_workqueue("ttyI3C", 0, 0); Can it happen that you already queue something on this wq, while not allocated yet? I mean: should this be done first in i3c_tty_init()? > + if (!workqueue) { > + ret = PTR_ERR(workqueue); > + goto err_alloc_workqueue; > + } > + > + return 0; > + > +err_alloc_workqueue: > + i3c_driver_unregister(&i3c_driver); > + > +err_i3c_driver_register: > + tty_unregister_driver(i3c_tty_driver); > + > +err_tty_register_driver: > + tty_driver_kref_put(i3c_tty_driver); > + > + return ret; > +} > + > +static void __exit i3c_tty_exit(void) > +{ > + i3c_driver_unregister(&i3c_driver); > + tty_unregister_driver(i3c_tty_driver); > + tty_driver_kref_put(i3c_tty_driver); > + idr_destroy(&i3c_tty_minors); What about the wq? > +} regards,
On Tue, Dec 05, 2023 at 10:56:09AM +0100, Jiri Slaby wrote: > On 30. 11. 23, 23:44, Frank Li wrote: > > In typical embedded Linux systems, UART consoles require at least two pins, > > TX and RX. In scenarios where I2C/I3C devices like sensors or PMICs are > > present, we can save these two pins by using this driver. Pins is crucial > > resources, especially in small chip packages. > > > > This introduces support for using the I3C bus to transfer console tty data, > > effectively replacing the need for dedicated UART pins. This not only > > conserves valuable pin resources but also facilitates testing of I3C's > > advanced features, including early termination, in-band interrupt (IBI) > > support, and the creation of more complex data patterns. Additionally, > > it aids in identifying and addressing issues within the I3C controller > > driver. > > > > Signed-off-by: Frank Li <Frank.Li@nxp.com> > ... > > --- a/drivers/tty/Kconfig > > +++ b/drivers/tty/Kconfig > > @@ -412,6 +412,19 @@ config RPMSG_TTY > > To compile this driver as a module, choose M here: the module will be > > called rpmsg_tty. > > +config I3C_TTY > > + tristate "TTY over I3C" > > + depends on I3C > > + help > > + Select this options if you'd like use TTY over I3C master controller > > this option > to use > add a period to the end. > > > + > > + This makes it possible for user-space programs to send and receive > > + data as a standard tty protocol. I3C provide relatively higher data > > + transfer rate and less pin numbers, SDA/SCL are shared with other > > + devices. > > + > > + If unsure, say N > > + > > endif # TTY > > source "drivers/tty/serdev/Kconfig" > ... > > --- /dev/null > > +++ b/drivers/tty/i3c_tty.c > > @@ -0,0 +1,443 @@ > ... > > +struct ttyi3c_port { > > + struct tty_port port; > > + int minor; > > + spinlock_t xlock; /* protect xmit */ > > + char tx_buff[I3C_TTY_TRANS_SIZE]; > > + char rx_buff[I3C_TTY_TRANS_SIZE]; > > These should be u8 as per the other changes throughout the tty layer. > > > + struct i3c_device *i3cdev; > > + struct work_struct txwork; > > + struct work_struct rxwork; > > + struct completion txcomplete; > > + unsigned long status; > > + int buf_overrun; > > Can this be ever negative? > > > +}; > > + > > +struct workqueue_struct *workqueue; > > Is this related: > Still below items not be fixed (according to Jiri Slaby's comments) > - rxwork thread: need trigger from two position. > - common thread queue: need some suggestion > ? > > As I don't remember, could you elaborate again why you need your own > workqueue? You need to do it in the commit log anyway. I just learn from other drivers, such as USB ACM, usb gadget ACM driver. If use common workqueue, which one prefered. I will send fixed version after i3c part accepted. Frank > > ... > > +static ssize_t i3c_write(struct tty_struct *tty, const unsigned char *buf, size_t count) > > +{ > > + struct ttyi3c_port *sport = tty->driver_data; > > + unsigned long flags; > > + bool is_empty; > > + int ret; > > + > > + spin_lock_irqsave(&sport->xlock, flags); > > + ret = kfifo_in(&sport->port.xmit_fifo, buf, count); > > + is_empty = kfifo_is_empty(&sport->port.xmit_fifo); > > + spin_unlock_irqrestore(&sport->xlock, flags); > > + > > + if (!is_empty) > > + queue_work(workqueue, &sport->txwork); > > + > > + return ret; > > +} > > + > > +static int i3c_put_char(struct tty_struct *tty, unsigned char ch) > > +{ > > + struct ttyi3c_port *sport = tty->driver_data; > > + unsigned long flags; > > + int ret = 0; > > Unneeded initialization. > > > + > > + spin_lock_irqsave(&sport->xlock, flags); > > + ret = kfifo_put(&sport->port.xmit_fifo, ch); > > + spin_unlock_irqrestore(&sport->xlock, flags); > > + > > + return ret; > > +} > ... > > +static void tty_i3c_rxwork(struct work_struct *work) > > +{ > > + struct ttyi3c_port *sport = container_of(work, struct ttyi3c_port, rxwork); > > + struct i3c_priv_xfer xfers; > > + int retry = I3C_TTY_RETRY; > > Likely, should be unsigned. > > > + u16 status = BIT(0); > > + int ret; > > + > > + memset(&xfers, 0, sizeof(xfers)); > > + xfers.data.in = sport->rx_buff; > > + xfers.len = I3C_TTY_TRANS_SIZE; > > + xfers.rnw = 1; > > + > > + do { > > + if (test_bit(I3C_TTY_RX_STOP, &sport->status)) > > + break; > > + > > + i3c_device_do_priv_xfers(sport->i3cdev, &xfers, 1); > > + > > + if (xfers.actual_len) { > > + ret = tty_insert_flip_string(&sport->port, sport->rx_buff, > > + xfers.actual_len); > > + if (ret < xfers.actual_len) > > + sport->buf_overrun++; > > + > > + retry = I3C_TTY_RETRY; > > + continue; > > + } > > + > > + status = BIT(0); > > + i3c_device_getstatus_format1(sport->i3cdev, &status); > > + /* > > + * Target side needs some time to fill data into fifo. Target side may not > > + * have hardware update status in real time. Software update status always > > + * needs some delays. > > + * > > + * Generally, target side have circular buffer in memory, it will be moved > > + * into FIFO by CPU or DMA. 'status' just show if circular buffer empty. But > > + * there are gap, especially CPU have not response irq to fill FIFO in time. > > + * So xfers.actual will be zero, wait for little time to avoid flood > > + * transfer in i3c bus. > > + */ > > + usleep_range(I3C_TTY_YIELD_US, 10 * I3C_TTY_YIELD_US); > > + retry--; > > + > > + } while (retry && (status & BIT(0))); > > + > > + tty_flip_buffer_push(&sport->port); > > +} > > + > > +static void tty_i3c_txwork(struct work_struct *work) > > +{ > > + struct ttyi3c_port *sport = container_of(work, struct ttyi3c_port, txwork); > > + struct i3c_priv_xfer xfers; > > + int retry = I3C_TTY_RETRY; > > Detto. > > > + unsigned long flags; > > + int ret; > > + > > + xfers.rnw = 0; > > + xfers.data.out = sport->tx_buff; > > + > > + while (!kfifo_is_empty(&sport->port.xmit_fifo) && retry) { > > + xfers.len = kfifo_len(&sport->port.xmit_fifo); > > + xfers.len = min_t(u16, I3C_TTY_TRANS_SIZE, xfers.len); > > + > > + xfers.len = kfifo_out_peek(&sport->port.xmit_fifo, sport->tx_buff, xfers.len); > > Can this simply be: > xfers.len = kfifo_out_peek(&sport->port.xmit_fifo, sport->tx_buff, > I3C_TTY_TRANS_SIZE); > ? > > > + > > + ret = i3c_device_do_priv_xfers(sport->i3cdev, &xfers, 1); > > + if (ret) { > > + /* > > + * Target side may not move data out of FIFO. delay can't resolve problem, > > + * just reduce some possiblity. Target can't end I3C SDR mode write > > + * transfer, discard data is reasonable when FIFO overrun. > > + */ > > + usleep_range(I3C_TTY_YIELD_US, 10 * I3C_TTY_YIELD_US); > > + retry--; > > + } else { > > + retry = I3C_TTY_RETRY; > > + ret = kfifo_out(&sport->port.xmit_fifo, sport->tx_buff, xfers.len); > > Just to make sure: xfers.len is nor overwritten by > i3c_device_do_priv_xfers(), right? > > > + } > > + } > > + > > + spin_lock_irqsave(&sport->xlock, flags); > > Why do you take the lock here, but not during the kfifo operations above? > > > + if (kfifo_is_empty(&sport->port.xmit_fifo)) > > + complete(&sport->txcomplete); > > + spin_unlock_irqrestore(&sport->xlock, flags); > > +} > > > +static int __init i3c_tty_init(void) > > +{ > > + int ret; > > + > > + i3c_tty_driver = tty_alloc_driver(I3C_TTY_MINORS, > > + TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV); > > + > > + if (IS_ERR(i3c_tty_driver)) > > + return PTR_ERR(i3c_tty_driver); > > + > > + i3c_tty_driver->driver_name = "ttyI3C"; > > + i3c_tty_driver->name = "ttyI3C"; > > + i3c_tty_driver->minor_start = 0, > > + i3c_tty_driver->type = TTY_DRIVER_TYPE_SERIAL, > > + i3c_tty_driver->subtype = SERIAL_TYPE_NORMAL, > > + i3c_tty_driver->init_termios = tty_std_termios; > > + i3c_tty_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | > > + CLOCAL; > > + i3c_tty_driver->init_termios.c_lflag = 0; > > + > > + tty_set_operations(i3c_tty_driver, &i3c_tty_ops); > > + > > + ret = tty_register_driver(i3c_tty_driver); > > + if (ret) > > + goto err_tty_register_driver; > > + > > + ret = i3c_driver_register(&i3c_driver); > > + if (ret) > > + goto err_i3c_driver_register; > > + > > + workqueue = alloc_workqueue("ttyI3C", 0, 0); > > Can it happen that you already queue something on this wq, while not > allocated yet? I mean: should this be done first in i3c_tty_init()? > > > + if (!workqueue) { > > + ret = PTR_ERR(workqueue); > > + goto err_alloc_workqueue; > > + } > > + > > + return 0; > > + > > +err_alloc_workqueue: > > + i3c_driver_unregister(&i3c_driver); > > + > > +err_i3c_driver_register: > > + tty_unregister_driver(i3c_tty_driver); > > + > > +err_tty_register_driver: > > + tty_driver_kref_put(i3c_tty_driver); > > + > > + return ret; > > +} > > + > > +static void __exit i3c_tty_exit(void) > > +{ > > + i3c_driver_unregister(&i3c_driver); > > + tty_unregister_driver(i3c_tty_driver); > > + tty_driver_kref_put(i3c_tty_driver); > > + idr_destroy(&i3c_tty_minors); > > What about the wq? > > > +} > > regards, > -- > js > suse labs >
diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig index 5646dc6242cd9..b13645f2d72bc 100644 --- a/drivers/tty/Kconfig +++ b/drivers/tty/Kconfig @@ -412,6 +412,19 @@ config RPMSG_TTY To compile this driver as a module, choose M here: the module will be called rpmsg_tty. +config I3C_TTY + tristate "TTY over I3C" + depends on I3C + help + Select this options if you'd like use TTY over I3C master controller + + This makes it possible for user-space programs to send and receive + data as a standard tty protocol. I3C provide relatively higher data + transfer rate and less pin numbers, SDA/SCL are shared with other + devices. + + If unsure, say N + endif # TTY source "drivers/tty/serdev/Kconfig" diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile index 07aca5184a55d..f329f9c7d308a 100644 --- a/drivers/tty/Makefile +++ b/drivers/tty/Makefile @@ -27,5 +27,6 @@ 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-$(CONFIG_I3C_TTY) += i3c_tty.o obj-y += ipwireless/ diff --git a/drivers/tty/i3c_tty.c b/drivers/tty/i3c_tty.c new file mode 100644 index 0000000000000..1497759cddb76 --- /dev/null +++ b/drivers/tty/i3c_tty.c @@ -0,0 +1,443 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2023 NXP. + * + * Author: Frank Li <Frank.Li@nxp.com> + */ + +#include <linux/delay.h> +#include <linux/kernel.h> +#include <linux/mod_devicetable.h> +#include <linux/module.h> +#include <linux/i3c/device.h> +#include <linux/i3c/master.h> +#include <linux/slab.h> +#include <linux/console.h> +#include <linux/serial_core.h> +#include <linux/interrupt.h> +#include <linux/workqueue.h> +#include <linux/tty_flip.h> + +static DEFINE_IDR(i3c_tty_minors); +static DEFINE_MUTEX(i3c_tty_minors_lock); + +static struct tty_driver *i3c_tty_driver; + +#define I3C_TTY_MINORS 256 +#define I3C_TTY_TRANS_SIZE 16 +#define I3C_TTY_RX_STOP 0 +#define I3C_TTY_RETRY 20 +#define I3C_TTY_YIELD_US 100 + +struct ttyi3c_port { + struct tty_port port; + int minor; + spinlock_t xlock; /* protect xmit */ + char tx_buff[I3C_TTY_TRANS_SIZE]; + char rx_buff[I3C_TTY_TRANS_SIZE]; + struct i3c_device *i3cdev; + struct work_struct txwork; + struct work_struct rxwork; + struct completion txcomplete; + unsigned long status; + int buf_overrun; +}; + +struct workqueue_struct *workqueue; + +static const struct i3c_device_id i3c_ids[] = { + I3C_DEVICE(0x011B, 0x1000, NULL), + { /* sentinel */ }, +}; + +static int i3c_port_activate(struct tty_port *port, struct tty_struct *tty) +{ + struct ttyi3c_port *sport = container_of(port, struct ttyi3c_port, port); + int ret; + + ret = tty_port_alloc_xmit_buf(port); + if (ret < 0) + return ret; + + sport->status = 0; + + ret = i3c_device_enable_ibi(sport->i3cdev); + if (ret) { + tty_port_free_xmit_buf(port); + return ret; + } + + return 0; +} + +static void i3c_port_shutdown(struct tty_port *port) +{ + struct ttyi3c_port *sport = + container_of(port, struct ttyi3c_port, port); + + i3c_device_disable_ibi(sport->i3cdev); + tty_port_free_xmit_buf(port); + kfree(sport->tx_buff); + kfree(sport->rx_buff); +} + +static void i3c_port_destruct(struct tty_port *port) +{ + struct ttyi3c_port *sport = + container_of(port, struct ttyi3c_port, port); + + mutex_lock(&i3c_tty_minors_lock); + idr_remove(&i3c_tty_minors, sport->minor); + mutex_unlock(&i3c_tty_minors_lock); +} + +static const struct tty_port_operations i3c_port_ops = { + .shutdown = i3c_port_shutdown, + .activate = i3c_port_activate, + .destruct = i3c_port_destruct, +}; + +static ssize_t i3c_write(struct tty_struct *tty, const unsigned char *buf, size_t count) +{ + struct ttyi3c_port *sport = tty->driver_data; + unsigned long flags; + bool is_empty; + int ret; + + spin_lock_irqsave(&sport->xlock, flags); + ret = kfifo_in(&sport->port.xmit_fifo, buf, count); + is_empty = kfifo_is_empty(&sport->port.xmit_fifo); + spin_unlock_irqrestore(&sport->xlock, flags); + + if (!is_empty) + queue_work(workqueue, &sport->txwork); + + return ret; +} + +static int i3c_put_char(struct tty_struct *tty, unsigned char ch) +{ + struct ttyi3c_port *sport = tty->driver_data; + unsigned long flags; + int ret = 0; + + spin_lock_irqsave(&sport->xlock, flags); + ret = kfifo_put(&sport->port.xmit_fifo, ch); + spin_unlock_irqrestore(&sport->xlock, flags); + + return ret; +} + +static void i3c_flush_chars(struct tty_struct *tty) +{ + struct ttyi3c_port *sport = tty->driver_data; + + queue_work(workqueue, &sport->txwork); +} + +static unsigned int i3c_write_room(struct tty_struct *tty) +{ + struct ttyi3c_port *sport = tty->driver_data; + + return kfifo_avail(&sport->port.xmit_fifo); +} + +static void i3c_throttle(struct tty_struct *tty) +{ + struct ttyi3c_port *sport = tty->driver_data; + + clear_bit(I3C_TTY_RX_STOP, &sport->status); +} + +static void i3c_unthrottle(struct tty_struct *tty) +{ + struct ttyi3c_port *sport = tty->driver_data; + + set_bit(I3C_TTY_RX_STOP, &sport->status); + + queue_work(workqueue, &sport->rxwork); +} + +static int i3c_open(struct tty_struct *tty, struct file *filp) +{ + struct ttyi3c_port *sport = container_of(tty->port, struct ttyi3c_port, port); + + tty->driver_data = sport; + + return tty_port_open(&sport->port, tty, filp); +} + +static void i3c_close(struct tty_struct *tty, struct file *filp) +{ + tty_port_close(tty->port, tty, filp); +} + +static void i3c_wait_until_sent(struct tty_struct *tty, int timeout) +{ + struct ttyi3c_port *sport = tty->driver_data; + + wait_for_completion_timeout(&sport->txcomplete, timeout); + reinit_completion(&sport->txcomplete); +} + +static const struct tty_operations i3c_tty_ops = { + .open = i3c_open, + .close = i3c_close, + .write = i3c_write, + .put_char = i3c_put_char, + .flush_chars = i3c_flush_chars, + .write_room = i3c_write_room, + .throttle = i3c_throttle, + .unthrottle = i3c_unthrottle, + .wait_until_sent = i3c_wait_until_sent, +}; + +static void i3c_controller_irq_handler(struct i3c_device *dev, + const struct i3c_ibi_payload *payload) +{ + struct ttyi3c_port *sport = dev_get_drvdata(&dev->dev); + + /* i3c_unthrottle also queue the work to fetch pending data in target side */ + queue_work(workqueue, &sport->rxwork); +} + +static void tty_i3c_rxwork(struct work_struct *work) +{ + struct ttyi3c_port *sport = container_of(work, struct ttyi3c_port, rxwork); + struct i3c_priv_xfer xfers; + int retry = I3C_TTY_RETRY; + u16 status = BIT(0); + int ret; + + memset(&xfers, 0, sizeof(xfers)); + xfers.data.in = sport->rx_buff; + xfers.len = I3C_TTY_TRANS_SIZE; + xfers.rnw = 1; + + do { + if (test_bit(I3C_TTY_RX_STOP, &sport->status)) + break; + + i3c_device_do_priv_xfers(sport->i3cdev, &xfers, 1); + + if (xfers.actual_len) { + ret = tty_insert_flip_string(&sport->port, sport->rx_buff, + xfers.actual_len); + if (ret < xfers.actual_len) + sport->buf_overrun++; + + retry = I3C_TTY_RETRY; + continue; + } + + status = BIT(0); + i3c_device_getstatus_format1(sport->i3cdev, &status); + /* + * Target side needs some time to fill data into fifo. Target side may not + * have hardware update status in real time. Software update status always + * needs some delays. + * + * Generally, target side have circular buffer in memory, it will be moved + * into FIFO by CPU or DMA. 'status' just show if circular buffer empty. But + * there are gap, especially CPU have not response irq to fill FIFO in time. + * So xfers.actual will be zero, wait for little time to avoid flood + * transfer in i3c bus. + */ + usleep_range(I3C_TTY_YIELD_US, 10 * I3C_TTY_YIELD_US); + retry--; + + } while (retry && (status & BIT(0))); + + tty_flip_buffer_push(&sport->port); +} + +static void tty_i3c_txwork(struct work_struct *work) +{ + struct ttyi3c_port *sport = container_of(work, struct ttyi3c_port, txwork); + struct i3c_priv_xfer xfers; + int retry = I3C_TTY_RETRY; + unsigned long flags; + int ret; + + xfers.rnw = 0; + xfers.data.out = sport->tx_buff; + + while (!kfifo_is_empty(&sport->port.xmit_fifo) && retry) { + xfers.len = kfifo_len(&sport->port.xmit_fifo); + xfers.len = min_t(u16, I3C_TTY_TRANS_SIZE, xfers.len); + + xfers.len = kfifo_out_peek(&sport->port.xmit_fifo, sport->tx_buff, xfers.len); + + ret = i3c_device_do_priv_xfers(sport->i3cdev, &xfers, 1); + if (ret) { + /* + * Target side may not move data out of FIFO. delay can't resolve problem, + * just reduce some possiblity. Target can't end I3C SDR mode write + * transfer, discard data is reasonable when FIFO overrun. + */ + usleep_range(I3C_TTY_YIELD_US, 10 * I3C_TTY_YIELD_US); + retry--; + } else { + retry = I3C_TTY_RETRY; + ret = kfifo_out(&sport->port.xmit_fifo, sport->tx_buff, xfers.len); + } + } + + spin_lock_irqsave(&sport->xlock, flags); + if (kfifo_is_empty(&sport->port.xmit_fifo)) + complete(&sport->txcomplete); + spin_unlock_irqrestore(&sport->xlock, flags); +} + +static int i3c_probe(struct i3c_device *i3cdev) +{ + struct ttyi3c_port *sport; + struct device *tty_dev; + struct i3c_ibi_setup req; + int minor; + int ret; + + sport = devm_kzalloc(&i3cdev->dev, sizeof(*sport), GFP_KERNEL); + if (!sport) + return -ENOMEM; + + sport->i3cdev = i3cdev; + + dev_set_drvdata(&i3cdev->dev, sport); + + req.max_payload_len = 8; + req.num_slots = 4; + req.handler = &i3c_controller_irq_handler; + + ret = i3c_device_request_ibi(i3cdev, &req); + if (ret) + return -EINVAL; + + mutex_lock(&i3c_tty_minors_lock); + minor = idr_alloc(&i3c_tty_minors, sport, 0, I3C_TTY_MINORS, GFP_KERNEL); + mutex_unlock(&i3c_tty_minors_lock); + + if (minor < 0) { + ret = -EINVAL; + goto err_idr_alloc; + } + + spin_lock_init(&sport->xlock); + INIT_WORK(&sport->txwork, tty_i3c_txwork); + INIT_WORK(&sport->rxwork, tty_i3c_rxwork); + init_completion(&sport->txcomplete); + + tty_port_init(&sport->port); + sport->port.ops = &i3c_port_ops; + + tty_dev = tty_port_register_device(&sport->port, i3c_tty_driver, minor, + &i3cdev->dev); + if (IS_ERR(tty_dev)) { + ret = PTR_ERR(tty_dev); + goto err_tty_port_register; + } + + sport->minor = minor; + + return 0; + +err_tty_port_register: + tty_port_put(&sport->port); + + mutex_lock(&i3c_tty_minors_lock); + idr_remove(&i3c_tty_minors, minor); + mutex_unlock(&i3c_tty_minors_lock); + +err_idr_alloc: + i3c_device_free_ibi(i3cdev); + + return ret; +} + +void i3c_remove(struct i3c_device *dev) +{ + struct ttyi3c_port *sport = dev_get_drvdata(&dev->dev); + + tty_port_unregister_device(&sport->port, i3c_tty_driver, sport->minor); + cancel_work_sync(&sport->txwork); + + tty_port_put(&sport->port); + + mutex_lock(&i3c_tty_minors_lock); + idr_remove(&i3c_tty_minors, sport->minor); + mutex_unlock(&i3c_tty_minors_lock); + + i3c_device_free_ibi(sport->i3cdev); +} + +static struct i3c_driver i3c_driver = { + .driver = { + .name = "ttyi3c", + }, + .probe = i3c_probe, + .remove = i3c_remove, + .id_table = i3c_ids, +}; + +static int __init i3c_tty_init(void) +{ + int ret; + + i3c_tty_driver = tty_alloc_driver(I3C_TTY_MINORS, + TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV); + + if (IS_ERR(i3c_tty_driver)) + return PTR_ERR(i3c_tty_driver); + + i3c_tty_driver->driver_name = "ttyI3C"; + i3c_tty_driver->name = "ttyI3C"; + i3c_tty_driver->minor_start = 0, + i3c_tty_driver->type = TTY_DRIVER_TYPE_SERIAL, + i3c_tty_driver->subtype = SERIAL_TYPE_NORMAL, + i3c_tty_driver->init_termios = tty_std_termios; + i3c_tty_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | + CLOCAL; + i3c_tty_driver->init_termios.c_lflag = 0; + + tty_set_operations(i3c_tty_driver, &i3c_tty_ops); + + ret = tty_register_driver(i3c_tty_driver); + if (ret) + goto err_tty_register_driver; + + ret = i3c_driver_register(&i3c_driver); + if (ret) + goto err_i3c_driver_register; + + workqueue = alloc_workqueue("ttyI3C", 0, 0); + if (!workqueue) { + ret = PTR_ERR(workqueue); + goto err_alloc_workqueue; + } + + return 0; + +err_alloc_workqueue: + i3c_driver_unregister(&i3c_driver); + +err_i3c_driver_register: + tty_unregister_driver(i3c_tty_driver); + +err_tty_register_driver: + tty_driver_kref_put(i3c_tty_driver); + + return ret; +} + +static void __exit i3c_tty_exit(void) +{ + i3c_driver_unregister(&i3c_driver); + tty_unregister_driver(i3c_tty_driver); + tty_driver_kref_put(i3c_tty_driver); + idr_destroy(&i3c_tty_minors); +} + +module_init(i3c_tty_init); +module_exit(i3c_tty_exit); + +MODULE_LICENSE("GPL");
In typical embedded Linux systems, UART consoles require at least two pins, TX and RX. In scenarios where I2C/I3C devices like sensors or PMICs are present, we can save these two pins by using this driver. Pins is crucial resources, especially in small chip packages. This introduces support for using the I3C bus to transfer console tty data, effectively replacing the need for dedicated UART pins. This not only conserves valuable pin resources but also facilitates testing of I3C's advanced features, including early termination, in-band interrupt (IBI) support, and the creation of more complex data patterns. Additionally, it aids in identifying and addressing issues within the I3C controller driver. Signed-off-by: Frank Li <Frank.Li@nxp.com> --- Notes: Change from v4 to v5 - send in i3c improvememtn patches. Change from v2 to v4 - none Change from v1 to v2 - update commit message. - using goto for err handle - using one working queue for all tty-i3c device - fixed typo found by js - update kconfig help - using kfifo Still below items not be fixed (according to Jiri Slaby's comments) - rxwork thread: need trigger from two position. - common thread queue: need some suggestion Some idea about i3c tty in future 1. early console support - early console is useful to debug boot problem. It requires as simple as possible. i3c SDR mode, 9th bit is parity. I3C target can't block master send out data. so never block kernel boot even without any expected target connected. i3c master may send out a boardcast message as early console to every target devices. Only a "i3c-usb-acm" can show it to host's minicom. And this "i3c-usb-acm" can plug in at any time. Write a boardcast message is quite simple at I3C controller. After kernel system boot to certain phase, switch to this driver. 2. multi port supports. create multi virtual uart ports, so firmware, such as arm trust firmware can dump message to difference virtual ports. 3. compatible with UART network adaptor, which defined at MIPI DEBUG for I3C spec. This driver is just first step. drivers/tty/Kconfig | 13 ++ drivers/tty/Makefile | 1 + drivers/tty/i3c_tty.c | 443 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 457 insertions(+) create mode 100644 drivers/tty/i3c_tty.c