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linux/drivers/tty/serial/21285.c
Greg Kroah-Hartman 293f899594 tty: serial: 21285: stop using the unused[] variable from struct uart_port 
Much like the samsung_tty driver (now I know where they copied the idea
from), the 21285 uart driver uses 2 bytes from the "unused" array of
struct uart_port to keep tx/rx enabled/disabled state.  Those fields are
going away (they were never really needed in the first place), so fix up
the 21285 driver by another horrible hack.

Instead of creating a whole structure for just 2 bytes, just use two
bits from the private_data pointer instead, as that pointer is never
used.  The two bits reflect if tx/rx is now enabled/disabled.

Astute readers will note that once rx is disabled, nothing ever seems to
turn it back on, making one wonder if anyone has ever done this.

Reported-by: kbuild test robot <lkp@intel.com>
Cc: Dmitry Safonov <dima@arista.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/r/20191219145109.GA1962496@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-12-19 20:10:28 +01:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Driver for the serial port on the 21285 StrongArm-110 core logic chip.
*
* Based on drivers/char/serial.c
*/
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/device.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/io.h>
#include <asm/irq.h>
#include <asm/mach-types.h>
#include <asm/system_info.h>
#include <asm/hardware/dec21285.h>
#include <mach/hardware.h>
#define BAUD_BASE (mem_fclk_21285/64)
#define SERIAL_21285_NAME "ttyFB"
#define SERIAL_21285_MAJOR 204
#define SERIAL_21285_MINOR 4
#define RXSTAT_DUMMY_READ 0x80000000
#define RXSTAT_FRAME (1 << 0)
#define RXSTAT_PARITY (1 << 1)
#define RXSTAT_OVERRUN (1 << 2)
#define RXSTAT_ANYERR (RXSTAT_FRAME|RXSTAT_PARITY|RXSTAT_OVERRUN)
#define H_UBRLCR_BREAK (1 << 0)
#define H_UBRLCR_PARENB (1 << 1)
#define H_UBRLCR_PAREVN (1 << 2)
#define H_UBRLCR_STOPB (1 << 3)
#define H_UBRLCR_FIFO (1 << 4)
static const char serial21285_name[] = "Footbridge UART";
/*
* We only need 2 bits of data, so instead of creating a whole structure for
* this, use bits of the private_data pointer of the uart port structure.
*/
#define tx_enabled_bit 0
#define rx_enabled_bit 1
static bool is_enabled(struct uart_port *port, int bit)
{
unsigned long private_data = (unsigned long)port->private_data;
if (test_bit(bit, &private_data))
return true;
return false;
}
static void enable(struct uart_port *port, int bit)
{
unsigned long private_data = (unsigned long)port->private_data;
set_bit(bit, &private_data);
}
static void disable(struct uart_port *port, int bit)
{
unsigned long private_data = (unsigned long)port->private_data;
clear_bit(bit, &private_data);
}
#define is_tx_enabled(port) is_enabled(port, tx_enabled_bit)
#define tx_enable(port) enable(port, tx_enabled_bit)
#define tx_disable(port) disable(port, tx_enabled_bit)
#define is_rx_enabled(port) is_enabled(port, rx_enabled_bit)
#define rx_enable(port) enable(port, rx_enabled_bit)
#define rx_disable(port) disable(port, rx_enabled_bit)
/*
* The documented expression for selecting the divisor is:
* BAUD_BASE / baud - 1
* However, typically BAUD_BASE is not divisible by baud, so
* we want to select the divisor that gives us the minimum
* error. Therefore, we want:
* int(BAUD_BASE / baud - 0.5) ->
* int(BAUD_BASE / baud - (baud >> 1) / baud) ->
* int((BAUD_BASE - (baud >> 1)) / baud)
*/
static void serial21285_stop_tx(struct uart_port *port)
{
if (is_tx_enabled(port)) {
disable_irq_nosync(IRQ_CONTX);
tx_disable(port);
}
}
static void serial21285_start_tx(struct uart_port *port)
{
if (!is_tx_enabled(port)) {
enable_irq(IRQ_CONTX);
tx_enable(port);
}
}
static void serial21285_stop_rx(struct uart_port *port)
{
if (is_rx_enabled(port)) {
disable_irq_nosync(IRQ_CONRX);
rx_disable(port);
}
}
static irqreturn_t serial21285_rx_chars(int irq, void *dev_id)
{
struct uart_port *port = dev_id;
unsigned int status, ch, flag, rxs, max_count = 256;
status = *CSR_UARTFLG;
while (!(status & 0x10) && max_count--) {
ch = *CSR_UARTDR;
flag = TTY_NORMAL;
port->icount.rx++;
rxs = *CSR_RXSTAT | RXSTAT_DUMMY_READ;
if (unlikely(rxs & RXSTAT_ANYERR)) {
if (rxs & RXSTAT_PARITY)
port->icount.parity++;
else if (rxs & RXSTAT_FRAME)
port->icount.frame++;
if (rxs & RXSTAT_OVERRUN)
port->icount.overrun++;
rxs &= port->read_status_mask;
if (rxs & RXSTAT_PARITY)
flag = TTY_PARITY;
else if (rxs & RXSTAT_FRAME)
flag = TTY_FRAME;
}
uart_insert_char(port, rxs, RXSTAT_OVERRUN, ch, flag);
status = *CSR_UARTFLG;
}
tty_flip_buffer_push(&port->state->port);
return IRQ_HANDLED;
}
static irqreturn_t serial21285_tx_chars(int irq, void *dev_id)
{
struct uart_port *port = dev_id;
struct circ_buf *xmit = &port->state->xmit;
int count = 256;
if (port->x_char) {
*CSR_UARTDR = port->x_char;
port->icount.tx++;
port->x_char = 0;
goto out;
}
if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
serial21285_stop_tx(port);
goto out;
}
do {
*CSR_UARTDR = xmit->buf[xmit->tail];
xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
port->icount.tx++;
if (uart_circ_empty(xmit))
break;
} while (--count > 0 && !(*CSR_UARTFLG & 0x20));
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(port);
if (uart_circ_empty(xmit))
serial21285_stop_tx(port);
out:
return IRQ_HANDLED;
}
static unsigned int serial21285_tx_empty(struct uart_port *port)
{
return (*CSR_UARTFLG & 8) ? 0 : TIOCSER_TEMT;
}
/* no modem control lines */
static unsigned int serial21285_get_mctrl(struct uart_port *port)
{
return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
}
static void serial21285_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
}
static void serial21285_break_ctl(struct uart_port *port, int break_state)
{
unsigned long flags;
unsigned int h_lcr;
spin_lock_irqsave(&port->lock, flags);
h_lcr = *CSR_H_UBRLCR;
if (break_state)
h_lcr |= H_UBRLCR_BREAK;
else
h_lcr &= ~H_UBRLCR_BREAK;
*CSR_H_UBRLCR = h_lcr;
spin_unlock_irqrestore(&port->lock, flags);
}
static int serial21285_startup(struct uart_port *port)
{
int ret;
tx_enable(port);
rx_enable(port);
ret = request_irq(IRQ_CONRX, serial21285_rx_chars, 0,
serial21285_name, port);
if (ret == 0) {
ret = request_irq(IRQ_CONTX, serial21285_tx_chars, 0,
serial21285_name, port);
if (ret)
free_irq(IRQ_CONRX, port);
}
return ret;
}
static void serial21285_shutdown(struct uart_port *port)
{
free_irq(IRQ_CONTX, port);
free_irq(IRQ_CONRX, port);
}
static void
serial21285_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
{
unsigned long flags;
unsigned int baud, quot, h_lcr, b;
/*
* We don't support modem control lines.
*/
termios->c_cflag &= ~(HUPCL | CRTSCTS | CMSPAR);
termios->c_cflag |= CLOCAL;
/*
* We don't support BREAK character recognition.
*/
termios->c_iflag &= ~(IGNBRK | BRKINT);
/*
* Ask the core to calculate the divisor for us.
*/
baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
quot = uart_get_divisor(port, baud);
b = port->uartclk / (16 * quot);
tty_termios_encode_baud_rate(termios, b, b);
switch (termios->c_cflag & CSIZE) {
case CS5:
h_lcr = 0x00;
break;
case CS6:
h_lcr = 0x20;
break;
case CS7:
h_lcr = 0x40;
break;
default: /* CS8 */
h_lcr = 0x60;
break;
}
if (termios->c_cflag & CSTOPB)
h_lcr |= H_UBRLCR_STOPB;
if (termios->c_cflag & PARENB) {
h_lcr |= H_UBRLCR_PARENB;
if (!(termios->c_cflag & PARODD))
h_lcr |= H_UBRLCR_PAREVN;
}
if (port->fifosize)
h_lcr |= H_UBRLCR_FIFO;
spin_lock_irqsave(&port->lock, flags);
/*
* Update the per-port timeout.
*/
uart_update_timeout(port, termios->c_cflag, baud);
/*
* Which character status flags are we interested in?
*/
port->read_status_mask = RXSTAT_OVERRUN;
if (termios->c_iflag & INPCK)
port->read_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
/*
* Which character status flags should we ignore?
*/
port->ignore_status_mask = 0;
if (termios->c_iflag & IGNPAR)
port->ignore_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
if (termios->c_iflag & IGNBRK && termios->c_iflag & IGNPAR)
port->ignore_status_mask |= RXSTAT_OVERRUN;
/*
* Ignore all characters if CREAD is not set.
*/
if ((termios->c_cflag & CREAD) == 0)
port->ignore_status_mask |= RXSTAT_DUMMY_READ;
quot -= 1;
*CSR_UARTCON = 0;
*CSR_L_UBRLCR = quot & 0xff;
*CSR_M_UBRLCR = (quot >> 8) & 0x0f;
*CSR_H_UBRLCR = h_lcr;
*CSR_UARTCON = 1;
spin_unlock_irqrestore(&port->lock, flags);
}
static const char *serial21285_type(struct uart_port *port)
{
return port->type == PORT_21285 ? "DC21285" : NULL;
}
static void serial21285_release_port(struct uart_port *port)
{
release_mem_region(port->mapbase, 32);
}
static int serial21285_request_port(struct uart_port *port)
{
return request_mem_region(port->mapbase, 32, serial21285_name)
!= NULL ? 0 : -EBUSY;
}
static void serial21285_config_port(struct uart_port *port, int flags)
{
if (flags & UART_CONFIG_TYPE && serial21285_request_port(port) == 0)
port->type = PORT_21285;
}
/*
* verify the new serial_struct (for TIOCSSERIAL).
*/
static int serial21285_verify_port(struct uart_port *port, struct serial_struct *ser)
{
int ret = 0;
if (ser->type != PORT_UNKNOWN && ser->type != PORT_21285)
ret = -EINVAL;
if (ser->irq <= 0)
ret = -EINVAL;
if (ser->baud_base != port->uartclk / 16)
ret = -EINVAL;
return ret;
}
static const struct uart_ops serial21285_ops = {
.tx_empty = serial21285_tx_empty,
.get_mctrl = serial21285_get_mctrl,
.set_mctrl = serial21285_set_mctrl,
.stop_tx = serial21285_stop_tx,
.start_tx = serial21285_start_tx,
.stop_rx = serial21285_stop_rx,
.break_ctl = serial21285_break_ctl,
.startup = serial21285_startup,
.shutdown = serial21285_shutdown,
.set_termios = serial21285_set_termios,
.type = serial21285_type,
.release_port = serial21285_release_port,
.request_port = serial21285_request_port,
.config_port = serial21285_config_port,
.verify_port = serial21285_verify_port,
};
static struct uart_port serial21285_port = {
.mapbase = 0x42000160,
.iotype = UPIO_MEM,
.irq = 0,
.fifosize = 16,
.ops = &serial21285_ops,
.flags = UPF_BOOT_AUTOCONF,
};
static void serial21285_setup_ports(void)
{
serial21285_port.uartclk = mem_fclk_21285 / 4;
}
#ifdef CONFIG_SERIAL_21285_CONSOLE
static void serial21285_console_putchar(struct uart_port *port, int ch)
{
while (*CSR_UARTFLG & 0x20)
barrier();
*CSR_UARTDR = ch;
}
static void
serial21285_console_write(struct console *co, const char *s,
unsigned int count)
{
uart_console_write(&serial21285_port, s, count, serial21285_console_putchar);
}
static void __init
serial21285_get_options(struct uart_port *port, int *baud,
int *parity, int *bits)
{
if (*CSR_UARTCON == 1) {
unsigned int tmp;
tmp = *CSR_H_UBRLCR;
switch (tmp & 0x60) {
case 0x00:
*bits = 5;
break;
case 0x20:
*bits = 6;
break;
case 0x40:
*bits = 7;
break;
default:
case 0x60:
*bits = 8;
break;
}
if (tmp & H_UBRLCR_PARENB) {
*parity = 'o';
if (tmp & H_UBRLCR_PAREVN)
*parity = 'e';
}
tmp = *CSR_L_UBRLCR | (*CSR_M_UBRLCR << 8);
*baud = port->uartclk / (16 * (tmp + 1));
}
}
static int __init serial21285_console_setup(struct console *co, char *options)
{
struct uart_port *port = &serial21285_port;
int baud = 9600;
int bits = 8;
int parity = 'n';
int flow = 'n';
if (machine_is_personal_server())
baud = 57600;
/*
* Check whether an invalid uart number has been specified, and
* if so, search for the first available port that does have
* console support.
*/
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
else
serial21285_get_options(port, &baud, &parity, &bits);
return uart_set_options(port, co, baud, parity, bits, flow);
}
static struct uart_driver serial21285_reg;
static struct console serial21285_console =
{
.name = SERIAL_21285_NAME,
.write = serial21285_console_write,
.device = uart_console_device,
.setup = serial21285_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &serial21285_reg,
};
static int __init rs285_console_init(void)
{
serial21285_setup_ports();
register_console(&serial21285_console);
return 0;
}
console_initcall(rs285_console_init);
#define SERIAL_21285_CONSOLE &serial21285_console
#else
#define SERIAL_21285_CONSOLE NULL
#endif
static struct uart_driver serial21285_reg = {
.owner = THIS_MODULE,
.driver_name = "ttyFB",
.dev_name = "ttyFB",
.major = SERIAL_21285_MAJOR,
.minor = SERIAL_21285_MINOR,
.nr = 1,
.cons = SERIAL_21285_CONSOLE,
};
static int __init serial21285_init(void)
{
int ret;
printk(KERN_INFO "Serial: 21285 driver\n");
serial21285_setup_ports();
ret = uart_register_driver(&serial21285_reg);
if (ret == 0)
uart_add_one_port(&serial21285_reg, &serial21285_port);
return ret;
}
static void __exit serial21285_exit(void)
{
uart_remove_one_port(&serial21285_reg, &serial21285_port);
uart_unregister_driver(&serial21285_reg);
}
module_init(serial21285_init);
module_exit(serial21285_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Intel Footbridge (21285) serial driver");
MODULE_ALIAS_CHARDEV(SERIAL_21285_MAJOR, SERIAL_21285_MINOR);
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