// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2008 Christian Pellegrin <[email protected]>
*
* Notes: the MAX3100 doesn't provide an interrupt on CTS so we have
* to use polling for flow control. TX empty IRQ is unusable, since
* writing conf clears FIFO buffer and we cannot have this interrupt
* always asking us for attention.
*
* The initial minor number is 209 in the low-density serial port:
* mknod /dev/ttyMAX0 c 204 209
*/
#define MAX3100_MAJOR 204
#define MAX3100_MINOR 209
/* 4 MAX3100s should be enough for everyone */
#define MAX_MAX3100 4
#include <linux/container_of.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/freezer.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/pm.h>
#include <linux/property.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/tty_flip.h>
#include <linux/tty.h>
#include <linux/types.h>
#include <linux/unaligned.h>
#define MAX3100_C (1<<14)
#define MAX3100_D (0<<14)
#define MAX3100_W (1<<15)
#define MAX3100_RX (0<<15)
#define MAX3100_WC (MAX3100_W | MAX3100_C)
#define MAX3100_RC (MAX3100_RX | MAX3100_C)
#define MAX3100_WD (MAX3100_W | MAX3100_D)
#define MAX3100_RD (MAX3100_RX | MAX3100_D)
#define MAX3100_CMD (3 << 14)
#define MAX3100_T (1<<14)
#define MAX3100_R (1<<15)
#define MAX3100_FEN (1<<13)
#define MAX3100_SHDN (1<<12)
#define MAX3100_TM (1<<11)
#define MAX3100_RM (1<<10)
#define MAX3100_PM (1<<9)
#define MAX3100_RAM (1<<8)
#define MAX3100_IR (1<<7)
#define MAX3100_ST (1<<6)
#define MAX3100_PE (1<<5)
#define MAX3100_L (1<<4)
#define MAX3100_BAUD (0xf)
#define MAX3100_TE (1<<10)
#define MAX3100_RAFE (1<<10)
#define MAX3100_RTS (1<<9)
#define MAX3100_CTS (1<<9)
#define MAX3100_PT (1<<8)
#define MAX3100_DATA (0xff)
#define MAX3100_RT (MAX3100_R | MAX3100_T)
#define MAX3100_RTC (MAX3100_RT | MAX3100_CTS | MAX3100_RAFE)
/* the following simulate a status reg for ignore_status_mask */
#define MAX3100_STATUS_PE 1
#define MAX3100_STATUS_FE 2
#define MAX3100_STATUS_OE 4
struct max3100_port {
struct uart_port port;
struct spi_device *spi;
int cts; /* last CTS received for flow ctrl */
int tx_empty; /* last TX empty bit */
spinlock_t conf_lock; /* shared data */
int conf_commit; /* need to make changes */
int conf; /* configuration for the MAX31000
* (bits 0-7, bits 8-11 are irqs) */
int rts_commit; /* need to change rts */
int rts; /* rts status */
int baud; /* current baud rate */
int parity; /* keeps track if we should send parity */
#define MAX3100_PARITY_ON 1
#define MAX3100_PARITY_ODD 2
#define MAX3100_7BIT 4
int rx_enabled; /* if we should rx chars */
int minor; /* minor number */
int loopback_commit; /* need to change loopback */
int loopback; /* 1 if we are in loopback mode */
/* for handling irqs: need workqueue since we do spi_sync */
struct workqueue_struct *workqueue;
struct work_struct work;
/* set to 1 to make the workhandler exit as soon as possible */
int force_end_work;
/* need to know we are suspending to avoid deadlock on workqueue */
int suspending;
struct timer_list timer;
};
static inline struct max3100_port *to_max3100_port(struct uart_port *port)
{
return container_of(port, struct max3100_port, port);
}
static struct max3100_port *max3100s[MAX_MAX3100]; /* the chips */
static DEFINE_MUTEX(max3100s_lock); /* race on probe */
static int max3100_do_parity(struct max3100_port *s, u16 c)
{
int parity;
if (s->parity & MAX3100_PARITY_ODD)
parity = 1;
else
parity = 0;
if (s->parity & MAX3100_7BIT)
c &= 0x7f;
else
c &= 0xff;
parity = parity ^ (hweight8(c) & 1);
return parity;
}
static int max3100_check_parity(struct max3100_port *s, u16 c)
{
return max3100_do_parity(s, c) == ((c >> 8) & 1);
}
static void max3100_calc_parity(struct max3100_port *s, u16 *c)
{
if (s->parity & MAX3100_7BIT)
*c &= 0x7f;
else
*c &= 0xff;
if (s->parity & MAX3100_PARITY_ON)
*c |= max3100_do_parity(s, *c) << 8;
}
static int max3100_sr(struct max3100_port *s, u16 tx, u16 *rx)
{
struct spi_message message;
__be16 etx, erx;
int status;
struct spi_transfer tran = {
.tx_buf = &etx,
.rx_buf = &erx,
.len = 2,
};
etx = cpu_to_be16(tx);
spi_message_init(&message);
spi_message_add_tail(&tran, &message);
status = spi_sync(s->spi, &message);
if (status) {
dev_warn(&s->spi->dev, "error while calling spi_sync\n");
return -EIO;
}
*rx = be16_to_cpu(erx);
s->tx_empty = (*rx & MAX3100_T) > 0;
dev_dbg(&s->spi->dev, "%04x - %04x\n", tx, *rx);
return 0;
}
static int max3100_handlerx_unlocked(struct max3100_port *s, u16 rx)
{
unsigned int status = 0;
int ret = 0, cts;
u8 ch, flg;
if (rx & MAX3100_R && s->rx_enabled) {
dev_dbg(&s->spi->dev, "%s\n", __func__);
ch = rx & (s->parity & MAX3100_7BIT ? 0x7f : 0xff);
if (rx & MAX3100_RAFE) {
s->port.icount.frame++;
flg = TTY_FRAME;
status |= MAX3100_STATUS_FE;
} else {
if (s->parity & MAX3100_PARITY_ON) {
if (max3100_check_parity(s, rx)) {
s->port.icount.rx++;
flg = TTY_NORMAL;
} else {
s->port.icount.parity++;
flg = TTY_PARITY;
status |= MAX3100_STATUS_PE;
}
} else {
s->port.icount.rx++;
flg = TTY_NORMAL;
}
}
uart_insert_char(&s->port, status, MAX3100_STATUS_OE, ch, flg);
ret = 1;
}
cts = (rx & MAX3100_CTS) > 0;
if (s->cts != cts) {
s->cts = cts;
uart_handle_cts_change(&s->port, cts);
}
return ret;
}
static int max3100_handlerx(struct max3100_port *s, u16 rx)
{
unsigned long flags;
int ret;
uart_port_lock_irqsave(&s->port, &flags);
ret = max3100_handlerx_unlocked(s, rx);
uart_port_unlock_irqrestore(&s->port, flags);
return ret;
}
static void max3100_work(struct work_struct *w)
{
struct max3100_port *s = container_of(w, struct max3100_port, work);
struct tty_port *tport = &s->port.state->port;
unsigned char ch;
int conf, cconf, cloopback, crts;
int rxchars;
u16 tx, rx;
dev_dbg(&s->spi->dev, "%s\n", __func__);
rxchars = 0;
do {
spin_lock(&s->conf_lock);
conf = s->conf;
cconf = s->conf_commit;
s->conf_commit = 0;
cloopback = s->loopback_commit;
s->loopback_commit = 0;
crts = s->rts_commit;
s->rts_commit = 0;
spin_unlock(&s->conf_lock);
if (cconf)
max3100_sr(s, MAX3100_WC | conf, &rx);
if (cloopback)
max3100_sr(s, 0x4001, &rx);
if (crts) {
max3100_sr(s, MAX3100_WD | MAX3100_TE |
(s->rts ? MAX3100_RTS : 0), &rx);
rxchars += max3100_handlerx(s, rx);
}
max3100_sr(s, MAX3100_RD, &rx);
rxchars += max3100_handlerx(s, rx);
if (rx & MAX3100_T) {
tx = 0xffff;
if (s->port.x_char) {
tx = s->port.x_char;
s->port.icount.tx++;
s->port.x_char = 0;
} else if (!uart_tx_stopped(&s->port) &&
uart_fifo_get(&s->port, &ch)) {
tx = ch;
}
if (tx != 0xffff) {
max3100_calc_parity(s, &tx);
tx |= MAX3100_WD | (s->rts ? MAX3100_RTS : 0);
max3100_sr(s, tx, &rx);
rxchars += max3100_handlerx(s, rx);
}
}
if (rxchars > 16) {
tty_flip_buffer_push(&s->port.state->port);
rxchars = 0;
}
if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
uart_write_wakeup(&s->port);
} while (!s->force_end_work &&
!freezing(current) &&
((rx & MAX3100_R) ||
(!kfifo_is_empty(&tport->xmit_fifo) &&
!uart_tx_stopped(&s->port))));
if (rxchars > 0)
tty_flip_buffer_push(&s->port.state->port);
}
static void max3100_dowork(struct max3100_port *s)
{
if (!s->force_end_work && !freezing(current) && !s->suspending)
queue_work(s->workqueue, &s->work);
}
static void max3100_timeout(struct timer_list *t)
{
struct max3100_port *s = from_timer(s, t, timer);
max3100_dowork(s);
mod_timer(&s->timer, jiffies + uart_poll_timeout(&s->port));
}
static irqreturn_t max3100_irq(int irqno, void *dev_id)
{
struct max3100_port *s = dev_id;
dev_dbg(&s->spi->dev, "%s\n", __func__);
max3100_dowork(s);
return IRQ_HANDLED;
}
static void max3100_enable_ms(struct uart_port *port)
{
struct max3100_port *s = to_max3100_port(port);
mod_timer(&s->timer, jiffies);
dev_dbg(&s->spi->dev, "%s\n", __func__);
}
static void max3100_start_tx(struct uart_port *port)
{
struct max3100_port *s = to_max3100_port(port);
dev_dbg(&s->spi->dev, "%s\n", __func__);
max3100_dowork(s);
}
static void max3100_stop_rx(struct uart_port *port)
{
struct max3100_port *s = to_max3100_port(port);
dev_dbg(&s->spi->dev, "%s\n", __func__);
s->rx_enabled = 0;
spin_lock(&s->conf_lock);
s->conf &= ~MAX3100_RM;
s->conf_commit = 1;
spin_unlock(&s->conf_lock);
max3100_dowork(s);
}
static unsigned int max3100_tx_empty(struct uart_port *port)
{
struct max3100_port *s = to_max3100_port(port);
dev_dbg(&s->spi->dev, "%s\n", __func__);
/* may not be truly up-to-date */
max3100_dowork(s);
return s->tx_empty;
}
static unsigned int max3100_get_mctrl(struct uart_port *port)
{
struct max3100_port *s = to_max3100_port(port);
dev_dbg(&s->spi->dev, "%s\n", __func__);
/* may not be truly up-to-date */
max3100_dowork(s);
/* always assert DCD and DSR since these lines are not wired */
return (s->cts ? TIOCM_CTS : 0) | TIOCM_DSR | TIOCM_CAR;
}
static void max3100_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
struct max3100_port *s = to_max3100_port(port);
int loopback, rts;
dev_dbg(&s->spi->dev, "%s\n", __func__);
loopback = (mctrl & TIOCM_LOOP) > 0;
rts = (mctrl & TIOCM_RTS) > 0;
spin_lock(&s->conf_lock);
if (s->loopback != loopback) {
s->loopback = loopback;
s->loopback_commit = 1;
}
if (s->rts != rts) {
s->rts = rts;
s->rts_commit = 1;
}
if (s->loopback_commit || s->rts_commit)
max3100_dowork(s);
spin_unlock(&s->conf_lock);
}
static void
max3100_set_termios(struct uart_port *port, struct ktermios *termios,
const struct ktermios *old)
{
struct max3100_port *s = to_max3100_port(port);
unsigned int baud = port->uartclk / 16;
unsigned int baud230400 = (baud == 230400) ? 1 : 0;
unsigned cflag;
u32 param_new, param_mask, parity = 0;
dev_dbg(&s->spi->dev, "%s\n", __func__);
cflag = termios->c_cflag;
param_mask = 0;
baud = tty_termios_baud_rate(termios);
param_new = s->conf & MAX3100_BAUD;
switch (baud) {
case 300:
if (baud230400)
baud = s->baud;
else
param_new = 15;
break;
case 600:
param_new = 14 + baud230400;
break;
case 1200:
param_new = 13 + baud230400;
break;
case 2400:
param_new = 12 + baud230400;
break;
case 4800:
param_new = 11 + baud230400;
break;
case 9600:
param_new = 10 + baud230400;
break;
case 19200:
param_new = 9 + baud230400;
break;
case 38400:
param_new = 8 + baud230400;
break;
case 57600:
param_new = 1 + baud230400;
break;
case 115200:
param_new = 0 + baud230400;
break;
case 230400:
if (baud230400)
param_new = 0;
else
baud = s->baud;
break;
default:
baud = s->baud;
}
tty_termios_encode_baud_rate(termios, baud, baud);
s->baud = baud;
param_mask |= MAX3100_BAUD;
if ((cflag & CSIZE) == CS8) {
param_new &= ~MAX3100_L;
parity &= ~MAX3100_7BIT;
} else {
param_new |= MAX3100_L;
parity |= MAX3100_7BIT;
cflag = (cflag & ~CSIZE) | CS7;
}
param_mask |= MAX3100_L;
if (cflag & CSTOPB)
param_new |= MAX3100_ST;
else
param_new &= ~MAX3100_ST;
param_mask |= MAX3100_ST;
if (cflag & PARENB) {
param_new |= MAX3100_PE;
parity |= MAX3100_PARITY_ON;
} else {
param_new &= ~MAX3100_PE;
parity &= ~MAX3100_PARITY_ON;
}
param_mask |= MAX3100_PE;
if (cflag & PARODD)
parity |= MAX3100_PARITY_ODD;
else
parity &= ~MAX3100_PARITY_ODD;
/* mask termios capabilities we don't support */
cflag &= ~CMSPAR;
termios->c_cflag = cflag;
s->port.ignore_status_mask = 0;
if (termios->c_iflag & IGNPAR)
s->port.ignore_status_mask |=
MAX3100_STATUS_PE | MAX3100_STATUS_FE |
MAX3100_STATUS_OE;
del_timer_sync(&s->timer);
uart_update_timeout(port, termios->c_cflag, baud);
spin_lock(&s->conf_lock);
s->conf = (s->conf & ~param_mask) | (param_new & param_mask);
s->conf_commit = 1;
s->parity = parity;
spin_unlock(&s->conf_lock);
max3100_dowork(s);
if (UART_ENABLE_MS(&s->port, termios->c_cflag))
max3100_enable_ms(&s->port);
}
static void max3100_shutdown(struct uart_port *port)
{
struct max3100_port *s = to_max3100_port(port);
u16 rx;
dev_dbg(&s->spi->dev, "%s\n", __func__);
if (s->suspending)
return;
s->force_end_work = 1;
del_timer_sync(&s->timer);
if (s->workqueue) {
destroy_workqueue(s->workqueue);
s->workqueue = NULL;
}
if (port->irq)
free_irq(port->irq, s);
/* set shutdown mode to save power */
max3100_sr(s, MAX3100_WC | MAX3100_SHDN, &rx);
}
static int max3100_startup(struct uart_port *port)
{
struct max3100_port *s = to_max3100_port(port);
char b[12];
int ret;
dev_dbg(&s->spi->dev, "%s\n", __func__);
s->conf = MAX3100_RM;
s->baud = port->uartclk / 16;
s->rx_enabled = 1;
if (s->suspending)
return 0;
s->force_end_work = 0;
s->parity = 0;
s->rts = 0;
sprintf(b, "max3100-%d", s->minor);
s->workqueue = create_freezable_workqueue(b);
if (!s->workqueue) {
dev_warn(&s->spi->dev, "cannot create workqueue\n");
return -EBUSY;
}
INIT_WORK(&s->work, max3100_work);
ret = request_irq(port->irq, max3100_irq, IRQF_TRIGGER_FALLING, "max3100", s);
if (ret < 0) {
dev_warn(&s->spi->dev, "cannot allocate irq %d\n", port->irq);
port->irq = 0;
destroy_workqueue(s->workqueue);
s->workqueue = NULL;
return -EBUSY;
}
s->conf_commit = 1;
max3100_dowork(s);
/* wait for clock to settle */
msleep(50);
max3100_enable_ms(&s->port);
return 0;
}
static const char *max3100_type(struct uart_port *port)
{
struct max3100_port *s = to_max3100_port(port);
dev_dbg(&s->spi->dev, "%s\n", __func__);
return s->port.type == PORT_MAX3100 ? "MAX3100" : NULL;
}
static void max3100_release_port(struct uart_port *port)
{
struct max3100_port *s = to_max3100_port(port);
dev_dbg(&s->spi->dev, "%s\n", __func__);
}
static void max3100_config_port(struct uart_port *port, int flags)
{
struct max3100_port *s = to_max3100_port(port);
dev_dbg(&s->spi->dev, "%s\n", __func__);
if (flags & UART_CONFIG_TYPE)
s->port.type = PORT_MAX3100;
}
static int max3100_verify_port(struct uart_port *port,
struct serial_struct *ser)
{
struct max3100_port *s = to_max3100_port(port);
int ret = -EINVAL;
dev_dbg(&s->spi->dev, "%s\n", __func__);
if (ser->type == PORT_UNKNOWN || ser->type == PORT_MAX3100)
ret = 0;
return ret;
}
static void max3100_stop_tx(struct uart_port *port)
{
struct max3100_port *s = to_max3100_port(port);
dev_dbg(&s->spi->dev, "%s\n", __func__);
}
static int max3100_request_port(struct uart_port *port)
{
struct max3100_port *s = to_max3100_port(port);
dev_dbg(&s->spi->dev, "%s\n", __func__);
return 0;
}
static void max3100_break_ctl(struct uart_port *port, int break_state)
{
struct max3100_port *s = to_max3100_port(port);
dev_dbg(&s->spi->dev, "%s\n", __func__);
}
static const struct uart_ops max3100_ops = {
.tx_empty = max3100_tx_empty,
.set_mctrl = max3100_set_mctrl,
.get_mctrl = max3100_get_mctrl,
.stop_tx = max3100_stop_tx,
.start_tx = max3100_start_tx,
.stop_rx = max3100_stop_rx,
.enable_ms = max3100_enable_ms,
.break_ctl = max3100_break_ctl,
.startup = max3100_startup,
.shutdown = max3100_shutdown,
.set_termios = max3100_set_termios,
.type = max3100_type,
.release_port = max3100_release_port,
.request_port = max3100_request_port,
.config_port = max3100_config_port,
.verify_port = max3100_verify_port,
};
static struct uart_driver max3100_uart_driver = {
.owner = THIS_MODULE,
.driver_name = "ttyMAX",
.dev_name = "ttyMAX",
.major = MAX3100_MAJOR,
.minor = MAX3100_MINOR,
.nr = MAX_MAX3100,
};
static int uart_driver_registered;
static int max3100_probe(struct spi_device *spi)
{
struct device *dev = &spi->dev;
int i, retval;
u16 rx;
mutex_lock(&max3100s_lock);
if (!uart_driver_registered) {
retval = uart_register_driver(&max3100_uart_driver);
if (retval) {
mutex_unlock(&max3100s_lock);
return dev_err_probe(dev, retval, "Couldn't register max3100 uart driver\n");
}
uart_driver_registered = 1;
}
for (i = 0; i < MAX_MAX3100; i++)
if (!max3100s[i])
break;
if (i == MAX_MAX3100) {
mutex_unlock(&max3100s_lock);
return dev_err_probe(dev, -ENOMEM, "too many MAX3100 chips\n");
}
max3100s[i] = kzalloc(sizeof(struct max3100_port), GFP_KERNEL);
if (!max3100s[i]) {
mutex_unlock(&max3100s_lock);
return -ENOMEM;
}
max3100s[i]->spi = spi;
spin_lock_init(&max3100s[i]->conf_lock);
spi_set_drvdata(spi, max3100s[i]);
max3100s[i]->minor = i;
timer_setup(&max3100s[i]->timer, max3100_timeout, 0);
dev_dbg(&spi->dev, "%s: adding port %d\n", __func__, i);
max3100s[i]->port.irq = spi->irq;
max3100s[i]->port.fifosize = 16;
max3100s[i]->port.ops = &max3100_ops;
max3100s[i]->port.flags = UPF_SKIP_TEST | UPF_BOOT_AUTOCONF;
max3100s[i]->port.line = i;
max3100s[i]->port.type = PORT_MAX3100;
max3100s[i]->port.dev = &spi->dev;
/* Read clock frequency from a property, uart_add_one_port() will fail if it's not set */
device_property_read_u32(dev, "clock-frequency", &max3100s[i]->port.uartclk);
retval = uart_add_one_port(&max3100_uart_driver, &max3100s[i]->port);
if (retval < 0)
dev_err_probe(dev, retval, "uart_add_one_port failed for line %d\n", i);
/* set shutdown mode to save power. Will be woken-up on open */
max3100_sr(max3100s[i], MAX3100_WC | MAX3100_SHDN, &rx);
mutex_unlock(&max3100s_lock);
return 0;
}
static void max3100_remove(struct spi_device *spi)
{
struct max3100_port *s = spi_get_drvdata(spi);
int i;
mutex_lock(&max3100s_lock);
/* find out the index for the chip we are removing */
for (i = 0; i < MAX_MAX3100; i++)
if (max3100s[i] == s) {
dev_dbg(&spi->dev, "%s: removing port %d\n", __func__, i);
uart_remove_one_port(&max3100_uart_driver, &max3100s[i]->port);
kfree(max3100s[i]);
max3100s[i] = NULL;
break;
}
WARN_ON(i == MAX_MAX3100);
/* check if this is the last chip we have */
for (i = 0; i < MAX_MAX3100; i++)
if (max3100s[i]) {
mutex_unlock(&max3100s_lock);
return;
}
pr_debug("removing max3100 driver\n");
uart_unregister_driver(&max3100_uart_driver);
uart_driver_registered = 0;
mutex_unlock(&max3100s_lock);
}
static int max3100_suspend(struct device *dev)
{
struct max3100_port *s = dev_get_drvdata(dev);
u16 rx;
dev_dbg(&s->spi->dev, "%s\n", __func__);
disable_irq(s->port.irq);
s->suspending = 1;
uart_suspend_port(&max3100_uart_driver, &s->port);
/* no HW suspend, so do SW one */
max3100_sr(s, MAX3100_WC | MAX3100_SHDN, &rx);
return 0;
}
static int max3100_resume(struct device *dev)
{
struct max3100_port *s = dev_get_drvdata(dev);
dev_dbg(&s->spi->dev, "%s\n", __func__);
uart_resume_port(&max3100_uart_driver, &s->port);
s->suspending = 0;
enable_irq(s->port.irq);
s->conf_commit = 1;
if (s->workqueue)
max3100_dowork(s);
return 0;
}
static DEFINE_SIMPLE_DEV_PM_OPS(max3100_pm_ops, max3100_suspend, max3100_resume);
static const struct spi_device_id max3100_spi_id[] = {
{ "max3100" },
{ }
};
MODULE_DEVICE_TABLE(spi, max3100_spi_id);
static const struct of_device_id max3100_of_match[] = {
{ .compatible = "maxim,max3100" },
{ }
};
MODULE_DEVICE_TABLE(of, max3100_of_match);
static struct spi_driver max3100_driver = {
.driver = {
.name = "max3100",
.of_match_table = max3100_of_match,
.pm = pm_sleep_ptr(&max3100_pm_ops),
},
.probe = max3100_probe,
.remove = max3100_remove,
.id_table = max3100_spi_id,
};
module_spi_driver(max3100_driver);
MODULE_DESCRIPTION("MAX3100 driver");
MODULE_AUTHOR("Christian Pellegrin <[email protected]>");
MODULE_LICENSE("GPL");
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