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linux/drivers/tty/serial/dz.c
Xin Zhao eb3b0d92c9 tty: tty_port: add workqueue to flip TTY buffer 
On the embedded platform, certain critical data, such as IMU data, is
transmitted through UART. The tty_flip_buffer_push() interface in the TTY
layer uses system_dfl_wq to handle the flipping of the TTY buffer.
Although the unbound workqueue can create new threads on demand and wake
up the kworker thread on an idle CPU, it may be preempted by real-time
tasks or other high-prio tasks.

flush_to_ldisc() needs to wake up the relevant data handle thread. When
executing __wake_up_common_lock(), it calls spin_lock_irqsave(), which
does not disable preemption but disables migration in RT-Linux. This
prevents the kworker thread from being migrated to other cores by CPU's
balancing logic, resulting in long delays. The call trace is as follows:
    __wake_up_common_lock
    __wake_up
    ep_poll_callback
    __wake_up_common
    __wake_up_common_lock
    __wake_up
    n_tty_receive_buf_common
    n_tty_receive_buf2
    tty_ldisc_receive_buf
    tty_port_default_receive_buf
    flush_to_ldisc

In our system, the processing interval for each frame of IMU data
transmitted via UART can experience significant jitter due to this issue.
Instead of the expected 10 to 15 ms frame processing interval, we see
spikes up to 30 to 35 ms. Moreover, in just one or two hours, there can
be 2 to 3 occurrences of such high jitter, which is quite frequent. This
jitter exceeds the software's tolerable limit of 20 ms.

Introduce flip_wq in tty_port which can be set by tty_port_link_wq() or as
default linked to default workqueue allocated when tty_register_driver().
The default workqueue is allocated with flag WQ_SYSFS, so that cpumask and
nice can be set dynamically. The execution timing of tty_port_link_wq() is
not clearly restricted. The newly added function tty_port_link_driver_wq()
checks whether the flip_wq of the tty_port has already been assigned when
linking the default tty_driver's workqueue to the port. After the user has
set a custom workqueue for a certain tty_port using tty_port_link_wq(), the
system will only use this custom workqueue, even if tty_driver does not
have %TTY_DRIVER_NO_WORKQUEUE flag. When tty_port register device, flip_wq
link operation is done by tty_port_link_driver_wq(), but for in-memory
devices the link operation cannot cover all the cases. Although
tty_port_install() is dedicated for in-memory devices lik PTY to link port
allocated on demand, the logic of tty_port_install() is so simple that
people may not call it, vc_cons[0].d->port is one such case. We check the
buf.flip_wq when flip TTY buffer, if buf.flip_wq of TTY port is NULL, use
system_dfl_wq as a backup.

To avoid naming conflict of the default tty_driver's workqueue, using
'"%s-%s", driver->name, driver->driver_name' as the workqueue name. In
cases where driver_name is not specified and therefore is NULL, the
workqueue is not created. Drivers that do not define driver_name are
potentially in-memory devices like vty, which generally do not require
special workqueue settings. Even with the combination of name and
driver_name, the workqueue names can still be duplicated, as many tty
serial drivers use "ttyS" as dev_name and "serial" as driver_name. I
modified the conflicting driver_name of these drivers by appending a
suffix of _xx based on the corresponding .c file. If this modification is
not made, it could not only lead to duplicate workqueue names but also
result in duplicate entries for the /proc/tty/driver/<driver_name> nodes.

Introduce %TTY_DRIVER_NO_WORKQUEUE flag meaning not to create the
default single tty_driver workqueue. Two reasons why need to introduce the
%TTY_DRIVER_NO_WORKQUEUE flag:
1. If the WQ_SYSFS parameter is enabled, workqueue_sysfs_register() will
fail when trying to create a workqueue with the same name. The pty is an
example of this; if both CONFIG_LEGACY_PTYS and CONFIG_UNIX98_PTYS are
enabled, the call to tty_register_driver() in unix98_pty_init() will fail.
2. Different TTY ports may be used for different tasks, which may require
separate core binding control via workqueues. In this case, the workqueue
created by default in the TTY driver is unnecessary. Enabling this flag
prevents the creation of this redundant workqueue.

After applying this patch, we can set the related UART TTY flip buffer
workqueue by sysfs. We set the cpumask to CPU cores associated with the
IMU tasks, and set the nice to -20. Testing has shown significant
improvement in the previously described issue, with almost no stuttering
occurring anymore.

Tested-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Xin Zhao <jackzxcui1989@163.com>
Link: https://patch.msgid.link/20260213085039.3274704-1-jackzxcui1989@163.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-12 15:26:29 +01:00

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// SPDX-License-Identifier: GPL-2.0
/*
* dz.c: Serial port driver for DECstations equipped
* with the DZ chipset.
*
* Copyright (C) 1998 Olivier A. D. Lebaillif
*
* Email: olivier.lebaillif@ifrsys.com
*
* Copyright (C) 2004, 2006, 2007 Maciej W. Rozycki
*
* [31-AUG-98] triemer
* Changed IRQ to use Harald's dec internals interrupts.h
* removed base_addr code - moving address assignment to setup.c
* Changed name of dz_init to rs_init to be consistent with tc code
* [13-NOV-98] triemer fixed code to receive characters
* after patches by harald to irq code.
* [09-JAN-99] triemer minor fix for schedule - due to removal of timeout
* field from "current" - somewhere between 2.1.121 and 2.1.131
Qua Jun 27 15:02:26 BRT 2001
* [27-JUN-2001] Arnaldo Carvalho de Melo <acme@conectiva.com.br> - cleanups
*
* Parts (C) 1999 David Airlie, airlied@linux.ie
* [07-SEP-99] Bugfixes
*
* [06-Jan-2002] Russell King <rmk@arm.linux.org.uk>
* Converted to new serial core
*/
#undef DEBUG_DZ
#include <linux/bitops.h>
#include <linux/compiler.h>
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/module.h>
#include <linux/serial.h>
#include <linux/serial_core.h>
#include <linux/sysrq.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/atomic.h>
#include <linux/io.h>
#include <asm/bootinfo.h>
#include <asm/dec/interrupts.h>
#include <asm/dec/kn01.h>
#include <asm/dec/kn02.h>
#include <asm/dec/machtype.h>
#include <asm/dec/prom.h>
#include <asm/dec/system.h>
#include "dz.h"
MODULE_DESCRIPTION("DECstation DZ serial driver");
MODULE_LICENSE("GPL");
static char dz_name[] __initdata = "DECstation DZ serial driver version ";
static char dz_version[] __initdata = "1.04";
struct dz_port {
struct dz_mux *mux;
struct uart_port port;
unsigned int cflag;
};
struct dz_mux {
struct dz_port dport[DZ_NB_PORT];
atomic_t map_guard;
atomic_t irq_guard;
int initialised;
};
static struct dz_mux dz_mux;
static inline struct dz_port *to_dport(struct uart_port *uport)
{
return container_of(uport, struct dz_port, port);
}
/*
* ------------------------------------------------------------
* dz_in () and dz_out ()
*
* These routines are used to access the registers of the DZ
* chip, hiding relocation differences between implementation.
* ------------------------------------------------------------
*/
static u16 dz_in(struct dz_port *dport, unsigned offset)
{
void __iomem *addr = dport->port.membase + offset;
return readw(addr);
}
static void dz_out(struct dz_port *dport, unsigned offset, u16 value)
{
void __iomem *addr = dport->port.membase + offset;
writew(value, addr);
}
/*
* ------------------------------------------------------------
* rs_stop () and rs_start ()
*
* These routines are called before setting or resetting
* tty->flow.stopped. They enable or disable transmitter interrupts,
* as necessary.
* ------------------------------------------------------------
*/
static void dz_stop_tx(struct uart_port *uport)
{
struct dz_port *dport = to_dport(uport);
u16 tmp, mask = 1 << dport->port.line;
tmp = dz_in(dport, DZ_TCR); /* read the TX flag */
tmp &= ~mask; /* clear the TX flag */
dz_out(dport, DZ_TCR, tmp);
}
static void dz_start_tx(struct uart_port *uport)
{
struct dz_port *dport = to_dport(uport);
u16 tmp, mask = 1 << dport->port.line;
tmp = dz_in(dport, DZ_TCR); /* read the TX flag */
tmp |= mask; /* set the TX flag */
dz_out(dport, DZ_TCR, tmp);
}
static void dz_stop_rx(struct uart_port *uport)
{
struct dz_port *dport = to_dport(uport);
dport->cflag &= ~DZ_RXENAB;
dz_out(dport, DZ_LPR, dport->cflag);
}
/*
* ------------------------------------------------------------
*
* Here start the interrupt handling routines. All of the following
* subroutines are declared as inline and are folded into
* dz_interrupt. They were separated out for readability's sake.
*
* Note: dz_interrupt() is a "fast" interrupt, which means that it
* runs with interrupts turned off. People who may want to modify
* dz_interrupt() should try to keep the interrupt handler as fast as
* possible. After you are done making modifications, it is not a bad
* idea to do:
*
* make drivers/serial/dz.s
*
* and look at the resulting assemble code in dz.s.
*
* ------------------------------------------------------------
*/
/*
* ------------------------------------------------------------
* receive_char ()
*
* This routine deals with inputs from any lines.
* ------------------------------------------------------------
*/
static inline void dz_receive_chars(struct dz_mux *mux)
{
struct uart_port *uport;
struct dz_port *dport = &mux->dport[0];
struct uart_icount *icount;
int lines_rx[DZ_NB_PORT] = { [0 ... DZ_NB_PORT - 1] = 0 };
u16 status;
u8 ch, flag;
int i;
while ((status = dz_in(dport, DZ_RBUF)) & DZ_DVAL) {
dport = &mux->dport[LINE(status)];
uport = &dport->port;
ch = UCHAR(status); /* grab the char */
flag = TTY_NORMAL;
icount = &uport->icount;
icount->rx++;
if (unlikely(status & (DZ_OERR | DZ_FERR | DZ_PERR))) {
/*
* There is no separate BREAK status bit, so treat
* null characters with framing errors as BREAKs;
* normally, otherwise. For this move the Framing
* Error bit to a simulated BREAK bit.
*/
if (!ch) {
status |= (status & DZ_FERR) >>
(ffs(DZ_FERR) - ffs(DZ_BREAK));
status &= ~DZ_FERR;
}
/* Handle SysRq/SAK & keep track of the statistics. */
if (status & DZ_BREAK) {
icount->brk++;
if (uart_handle_break(uport))
continue;
} else if (status & DZ_FERR)
icount->frame++;
else if (status & DZ_PERR)
icount->parity++;
if (status & DZ_OERR)
icount->overrun++;
status &= uport->read_status_mask;
if (status & DZ_BREAK)
flag = TTY_BREAK;
else if (status & DZ_FERR)
flag = TTY_FRAME;
else if (status & DZ_PERR)
flag = TTY_PARITY;
}
if (uart_handle_sysrq_char(uport, ch))
continue;
uart_insert_char(uport, status, DZ_OERR, ch, flag);
lines_rx[LINE(status)] = 1;
}
for (i = 0; i < DZ_NB_PORT; i++)
if (lines_rx[i])
tty_flip_buffer_push(&mux->dport[i].port.state->port);
}
/*
* ------------------------------------------------------------
* transmit_char ()
*
* This routine deals with outputs to any lines.
* ------------------------------------------------------------
*/
static inline void dz_transmit_chars(struct dz_mux *mux)
{
struct dz_port *dport = &mux->dport[0];
struct tty_port *tport;
unsigned char tmp;
u16 status;
status = dz_in(dport, DZ_CSR);
dport = &mux->dport[LINE(status)];
tport = &dport->port.state->port;
if (dport->port.x_char) { /* XON/XOFF chars */
dz_out(dport, DZ_TDR, dport->port.x_char);
dport->port.icount.tx++;
dport->port.x_char = 0;
return;
}
/* If nothing to do or stopped or hardware stopped. */
if (uart_tx_stopped(&dport->port) ||
!uart_fifo_get(&dport->port, &tmp)) {
uart_port_lock(&dport->port);
dz_stop_tx(&dport->port);
uart_port_unlock(&dport->port);
return;
}
/*
* If something to do... (remember the dz has no output fifo,
* so we go one char at a time) :-<
*/
dz_out(dport, DZ_TDR, tmp);
if (kfifo_len(&tport->xmit_fifo) < DZ_WAKEUP_CHARS)
uart_write_wakeup(&dport->port);
/* Are we are done. */
if (kfifo_is_empty(&tport->xmit_fifo)) {
uart_port_lock(&dport->port);
dz_stop_tx(&dport->port);
uart_port_unlock(&dport->port);
}
}
/*
* ------------------------------------------------------------
* check_modem_status()
*
* DS 3100 & 5100: Only valid for the MODEM line, duh!
* DS 5000/200: Valid for the MODEM and PRINTER line.
* ------------------------------------------------------------
*/
static inline void check_modem_status(struct dz_port *dport)
{
/*
* FIXME:
* 1. No status change interrupt; use a timer.
* 2. Handle the 3100/5000 as appropriate. --macro
*/
u16 status;
/* If not the modem line just return. */
if (dport->port.line != DZ_MODEM)
return;
status = dz_in(dport, DZ_MSR);
/* it's easy, since DSR2 is the only bit in the register */
if (status)
dport->port.icount.dsr++;
}
/*
* ------------------------------------------------------------
* dz_interrupt ()
*
* this is the main interrupt routine for the DZ chip.
* It deals with the multiple ports.
* ------------------------------------------------------------
*/
static irqreturn_t dz_interrupt(int irq, void *dev_id)
{
struct dz_mux *mux = dev_id;
struct dz_port *dport = &mux->dport[0];
u16 status;
/* get the reason why we just got an irq */
status = dz_in(dport, DZ_CSR);
if ((status & (DZ_RDONE | DZ_RIE)) == (DZ_RDONE | DZ_RIE))
dz_receive_chars(mux);
if ((status & (DZ_TRDY | DZ_TIE)) == (DZ_TRDY | DZ_TIE))
dz_transmit_chars(mux);
return IRQ_HANDLED;
}
/*
* -------------------------------------------------------------------
* Here ends the DZ interrupt routines.
* -------------------------------------------------------------------
*/
static unsigned int dz_get_mctrl(struct uart_port *uport)
{
/*
* FIXME: Handle the 3100/5000 as appropriate. --macro
*/
struct dz_port *dport = to_dport(uport);
unsigned int mctrl = TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
if (dport->port.line == DZ_MODEM) {
if (dz_in(dport, DZ_MSR) & DZ_MODEM_DSR)
mctrl &= ~TIOCM_DSR;
}
return mctrl;
}
static void dz_set_mctrl(struct uart_port *uport, unsigned int mctrl)
{
/*
* FIXME: Handle the 3100/5000 as appropriate. --macro
*/
struct dz_port *dport = to_dport(uport);
u16 tmp;
if (dport->port.line == DZ_MODEM) {
tmp = dz_in(dport, DZ_TCR);
if (mctrl & TIOCM_DTR)
tmp &= ~DZ_MODEM_DTR;
else
tmp |= DZ_MODEM_DTR;
dz_out(dport, DZ_TCR, tmp);
}
}
/*
* -------------------------------------------------------------------
* startup ()
*
* various initialization tasks
* -------------------------------------------------------------------
*/
static int dz_startup(struct uart_port *uport)
{
struct dz_port *dport = to_dport(uport);
struct dz_mux *mux = dport->mux;
unsigned long flags;
int irq_guard;
int ret;
u16 tmp;
irq_guard = atomic_add_return(1, &mux->irq_guard);
if (irq_guard != 1)
return 0;
ret = request_irq(dport->port.irq, dz_interrupt,
IRQF_SHARED, "dz", mux);
if (ret) {
atomic_add(-1, &mux->irq_guard);
printk(KERN_ERR "dz: Cannot get IRQ %d!\n", dport->port.irq);
return ret;
}
uart_port_lock_irqsave(&dport->port, &flags);
/* Enable interrupts. */
tmp = dz_in(dport, DZ_CSR);
tmp |= DZ_RIE | DZ_TIE;
dz_out(dport, DZ_CSR, tmp);
uart_port_unlock_irqrestore(&dport->port, flags);
return 0;
}
/*
* -------------------------------------------------------------------
* shutdown ()
*
* This routine will shutdown a serial port; interrupts are disabled, and
* DTR is dropped if the hangup on close termio flag is on.
* -------------------------------------------------------------------
*/
static void dz_shutdown(struct uart_port *uport)
{
struct dz_port *dport = to_dport(uport);
struct dz_mux *mux = dport->mux;
unsigned long flags;
int irq_guard;
u16 tmp;
uart_port_lock_irqsave(&dport->port, &flags);
dz_stop_tx(&dport->port);
uart_port_unlock_irqrestore(&dport->port, flags);
irq_guard = atomic_add_return(-1, &mux->irq_guard);
if (!irq_guard) {
/* Disable interrupts. */
tmp = dz_in(dport, DZ_CSR);
tmp &= ~(DZ_RIE | DZ_TIE);
dz_out(dport, DZ_CSR, tmp);
free_irq(dport->port.irq, mux);
}
}
/*
* -------------------------------------------------------------------
* dz_tx_empty() -- get the transmitter empty status
*
* Purpose: Let user call ioctl() to get info when the UART physically
* is emptied. On bus types like RS485, the transmitter must
* release the bus after transmitting. This must be done when
* the transmit shift register is empty, not be done when the
* transmit holding register is empty. This functionality
* allows an RS485 driver to be written in user space.
* -------------------------------------------------------------------
*/
static unsigned int dz_tx_empty(struct uart_port *uport)
{
struct dz_port *dport = to_dport(uport);
unsigned short tmp, mask = 1 << dport->port.line;
tmp = dz_in(dport, DZ_TCR);
tmp &= mask;
return tmp ? 0 : TIOCSER_TEMT;
}
static void dz_break_ctl(struct uart_port *uport, int break_state)
{
/*
* FIXME: Can't access BREAK bits in TDR easily;
* reuse the code for polled TX. --macro
*/
struct dz_port *dport = to_dport(uport);
unsigned long flags;
unsigned short tmp, mask = 1 << dport->port.line;
uart_port_lock_irqsave(uport, &flags);
tmp = dz_in(dport, DZ_TCR);
if (break_state)
tmp |= mask;
else
tmp &= ~mask;
dz_out(dport, DZ_TCR, tmp);
uart_port_unlock_irqrestore(uport, flags);
}
static int dz_encode_baud_rate(unsigned int baud)
{
switch (baud) {
case 50:
return DZ_B50;
case 75:
return DZ_B75;
case 110:
return DZ_B110;
case 134:
return DZ_B134;
case 150:
return DZ_B150;
case 300:
return DZ_B300;
case 600:
return DZ_B600;
case 1200:
return DZ_B1200;
case 1800:
return DZ_B1800;
case 2000:
return DZ_B2000;
case 2400:
return DZ_B2400;
case 3600:
return DZ_B3600;
case 4800:
return DZ_B4800;
case 7200:
return DZ_B7200;
case 9600:
return DZ_B9600;
default:
return -1;
}
}
static void dz_reset(struct dz_port *dport)
{
struct dz_mux *mux = dport->mux;
if (mux->initialised)
return;
dz_out(dport, DZ_CSR, DZ_CLR);
while (dz_in(dport, DZ_CSR) & DZ_CLR);
iob();
/* Enable scanning. */
dz_out(dport, DZ_CSR, DZ_MSE);
mux->initialised = 1;
}
static void dz_set_termios(struct uart_port *uport, struct ktermios *termios,
const struct ktermios *old_termios)
{
struct dz_port *dport = to_dport(uport);
unsigned long flags;
unsigned int cflag, baud;
int bflag;
cflag = dport->port.line;
switch (termios->c_cflag & CSIZE) {
case CS5:
cflag |= DZ_CS5;
break;
case CS6:
cflag |= DZ_CS6;
break;
case CS7:
cflag |= DZ_CS7;
break;
case CS8:
default:
cflag |= DZ_CS8;
}
if (termios->c_cflag & CSTOPB)
cflag |= DZ_CSTOPB;
if (termios->c_cflag & PARENB)
cflag |= DZ_PARENB;
if (termios->c_cflag & PARODD)
cflag |= DZ_PARODD;
baud = uart_get_baud_rate(uport, termios, old_termios, 50, 9600);
bflag = dz_encode_baud_rate(baud);
if (bflag < 0) {
if (old_termios) {
/* Keep unchanged. */
baud = tty_termios_baud_rate(old_termios);
bflag = dz_encode_baud_rate(baud);
}
if (bflag < 0) { /* Resort to 9600. */
baud = 9600;
bflag = DZ_B9600;
}
tty_termios_encode_baud_rate(termios, baud, baud);
}
cflag |= bflag;
if (termios->c_cflag & CREAD)
cflag |= DZ_RXENAB;
uart_port_lock_irqsave(&dport->port, &flags);
uart_update_timeout(uport, termios->c_cflag, baud);
dz_out(dport, DZ_LPR, cflag);
dport->cflag = cflag;
/* setup accept flag */
dport->port.read_status_mask = DZ_OERR;
if (termios->c_iflag & INPCK)
dport->port.read_status_mask |= DZ_FERR | DZ_PERR;
if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
dport->port.read_status_mask |= DZ_BREAK;
/* characters to ignore */
uport->ignore_status_mask = 0;
if ((termios->c_iflag & (IGNPAR | IGNBRK)) == (IGNPAR | IGNBRK))
dport->port.ignore_status_mask |= DZ_OERR;
if (termios->c_iflag & IGNPAR)
dport->port.ignore_status_mask |= DZ_FERR | DZ_PERR;
if (termios->c_iflag & IGNBRK)
dport->port.ignore_status_mask |= DZ_BREAK;
uart_port_unlock_irqrestore(&dport->port, flags);
}
/*
* Hack alert!
* Required solely so that the initial PROM-based console
* works undisturbed in parallel with this one.
*/
static void dz_pm(struct uart_port *uport, unsigned int state,
unsigned int oldstate)
{
struct dz_port *dport = to_dport(uport);
unsigned long flags;
uart_port_lock_irqsave(&dport->port, &flags);
if (state < 3)
dz_start_tx(&dport->port);
else
dz_stop_tx(&dport->port);
uart_port_unlock_irqrestore(&dport->port, flags);
}
static const char *dz_type(struct uart_port *uport)
{
return "DZ";
}
static void dz_release_port(struct uart_port *uport)
{
struct dz_mux *mux = to_dport(uport)->mux;
int map_guard;
iounmap(uport->membase);
uport->membase = NULL;
map_guard = atomic_add_return(-1, &mux->map_guard);
if (!map_guard)
release_mem_region(uport->mapbase, dec_kn_slot_size);
}
static int dz_map_port(struct uart_port *uport)
{
if (!uport->membase)
uport->membase = ioremap(uport->mapbase,
dec_kn_slot_size);
if (!uport->membase) {
printk(KERN_ERR "dz: Cannot map MMIO\n");
return -ENOMEM;
}
return 0;
}
static int dz_request_port(struct uart_port *uport)
{
struct dz_mux *mux = to_dport(uport)->mux;
int map_guard;
int ret;
map_guard = atomic_add_return(1, &mux->map_guard);
if (map_guard == 1) {
if (!request_mem_region(uport->mapbase, dec_kn_slot_size,
"dz")) {
atomic_add(-1, &mux->map_guard);
printk(KERN_ERR
"dz: Unable to reserve MMIO resource\n");
return -EBUSY;
}
}
ret = dz_map_port(uport);
if (ret) {
map_guard = atomic_add_return(-1, &mux->map_guard);
if (!map_guard)
release_mem_region(uport->mapbase, dec_kn_slot_size);
return ret;
}
return 0;
}
static void dz_config_port(struct uart_port *uport, int flags)
{
struct dz_port *dport = to_dport(uport);
if (flags & UART_CONFIG_TYPE) {
if (dz_request_port(uport))
return;
uport->type = PORT_DZ;
dz_reset(dport);
}
}
/*
* Verify the new serial_struct (for TIOCSSERIAL).
*/
static int dz_verify_port(struct uart_port *uport, struct serial_struct *ser)
{
int ret = 0;
if (ser->type != PORT_UNKNOWN && ser->type != PORT_DZ)
ret = -EINVAL;
if (ser->irq != uport->irq)
ret = -EINVAL;
return ret;
}
static const struct uart_ops dz_ops = {
.tx_empty = dz_tx_empty,
.get_mctrl = dz_get_mctrl,
.set_mctrl = dz_set_mctrl,
.stop_tx = dz_stop_tx,
.start_tx = dz_start_tx,
.stop_rx = dz_stop_rx,
.break_ctl = dz_break_ctl,
.startup = dz_startup,
.shutdown = dz_shutdown,
.set_termios = dz_set_termios,
.pm = dz_pm,
.type = dz_type,
.release_port = dz_release_port,
.request_port = dz_request_port,
.config_port = dz_config_port,
.verify_port = dz_verify_port,
};
static void __init dz_init_ports(void)
{
static int first = 1;
unsigned long base;
int line;
if (!first)
return;
first = 0;
if (mips_machtype == MACH_DS23100 || mips_machtype == MACH_DS5100)
base = dec_kn_slot_base + KN01_DZ11;
else
base = dec_kn_slot_base + KN02_DZ11;
for (line = 0; line < DZ_NB_PORT; line++) {
struct dz_port *dport = &dz_mux.dport[line];
struct uart_port *uport = &dport->port;
dport->mux = &dz_mux;
uport->irq = dec_interrupt[DEC_IRQ_DZ11];
uport->fifosize = 1;
uport->iotype = UPIO_MEM;
uport->flags = UPF_BOOT_AUTOCONF;
uport->ops = &dz_ops;
uport->line = line;
uport->mapbase = base;
uport->has_sysrq = IS_ENABLED(CONFIG_SERIAL_DZ_CONSOLE);
}
}
#ifdef CONFIG_SERIAL_DZ_CONSOLE
/*
* -------------------------------------------------------------------
* dz_console_putchar() -- transmit a character
*
* Polled transmission. This is tricky. We need to mask transmit
* interrupts so that they do not interfere, enable the transmitter
* for the line requested and then wait till the transmit scanner
* requests data for this line. But it may request data for another
* line first, in which case we have to disable its transmitter and
* repeat waiting till our line pops up. Only then the character may
* be transmitted. Finally, the state of the transmitter mask is
* restored. Welcome to the world of PDP-11!
* -------------------------------------------------------------------
*/
static void dz_console_putchar(struct uart_port *uport, unsigned char ch)
{
struct dz_port *dport = to_dport(uport);
unsigned long flags;
unsigned short csr, tcr, trdy, mask;
int loops = 10000;
uart_port_lock_irqsave(&dport->port, &flags);
csr = dz_in(dport, DZ_CSR);
dz_out(dport, DZ_CSR, csr & ~DZ_TIE);
tcr = dz_in(dport, DZ_TCR);
tcr |= 1 << dport->port.line;
mask = tcr;
dz_out(dport, DZ_TCR, mask);
iob();
uart_port_unlock_irqrestore(&dport->port, flags);
do {
trdy = dz_in(dport, DZ_CSR);
if (!(trdy & DZ_TRDY))
continue;
trdy = (trdy & DZ_TLINE) >> 8;
if (trdy == dport->port.line)
break;
mask &= ~(1 << trdy);
dz_out(dport, DZ_TCR, mask);
iob();
udelay(2);
} while (--loops);
if (loops) /* Cannot send otherwise. */
dz_out(dport, DZ_TDR, ch);
dz_out(dport, DZ_TCR, tcr);
dz_out(dport, DZ_CSR, csr);
}
/*
* -------------------------------------------------------------------
* dz_console_print ()
*
* dz_console_print is registered for printk.
* The console must be locked when we get here.
* -------------------------------------------------------------------
*/
static void dz_console_print(struct console *co,
const char *str,
unsigned int count)
{
struct dz_port *dport = &dz_mux.dport[co->index];
#ifdef DEBUG_DZ
prom_printf((char *) str);
#endif
uart_console_write(&dport->port, str, count, dz_console_putchar);
}
static int __init dz_console_setup(struct console *co, char *options)
{
struct dz_port *dport = &dz_mux.dport[co->index];
struct uart_port *uport = &dport->port;
int baud = 9600;
int bits = 8;
int parity = 'n';
int flow = 'n';
int ret;
ret = dz_map_port(uport);
if (ret)
return ret;
spin_lock_init(&dport->port.lock); /* For dz_pm(). */
dz_reset(dport);
dz_pm(uport, 0, -1);
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
return uart_set_options(&dport->port, co, baud, parity, bits, flow);
}
static struct uart_driver dz_reg;
static struct console dz_console = {
.name = "ttyS",
.write = dz_console_print,
.device = uart_console_device,
.setup = dz_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &dz_reg,
};
static int __init dz_serial_console_init(void)
{
if (!IOASIC) {
dz_init_ports();
register_console(&dz_console);
return 0;
} else
return -ENXIO;
}
console_initcall(dz_serial_console_init);
#define SERIAL_DZ_CONSOLE &dz_console
#else
#define SERIAL_DZ_CONSOLE NULL
#endif /* CONFIG_SERIAL_DZ_CONSOLE */
static struct uart_driver dz_reg = {
.owner = THIS_MODULE,
.driver_name = "serial_dz",
.dev_name = "ttyS",
.major = TTY_MAJOR,
.minor = 64,
.nr = DZ_NB_PORT,
.cons = SERIAL_DZ_CONSOLE,
};
static int __init dz_init(void)
{
int ret, i;
if (IOASIC)
return -ENXIO;
printk("%s%s\n", dz_name, dz_version);
dz_init_ports();
ret = uart_register_driver(&dz_reg);
if (ret)
return ret;
for (i = 0; i < DZ_NB_PORT; i++)
uart_add_one_port(&dz_reg, &dz_mux.dport[i].port);
return 0;
}
module_init(dz_init);
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