2 * Driver for AMBA serial ports
4 * Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
6 * Copyright 1999 ARM Limited
7 * Copyright (C) 2000 Deep Blue Solutions Ltd.
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 * This is a generic driver for ARM AMBA-type serial ports. They
24 * have a lot of 16550-like features, but are not register compatible.
25 * Note that although they do have CTS, DCD and DSR inputs, they do
26 * not have an RI input, nor do they have DTR or RTS outputs. If
27 * required, these have to be supplied via some other means (eg, GPIO)
28 * and hooked into this driver.
31 #if defined(CONFIG_SERIAL_AMBA_PL010_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
35 #include <linux/module.h>
36 #include <linux/ioport.h>
37 #include <linux/init.h>
38 #include <linux/console.h>
39 #include <linux/sysrq.h>
40 #include <linux/device.h>
41 #include <linux/tty.h>
42 #include <linux/tty_flip.h>
43 #include <linux/serial_core.h>
44 #include <linux/serial.h>
45 #include <linux/amba/bus.h>
46 #include <linux/amba/serial.h>
47 #include <linux/clk.h>
48 #include <linux/slab.h>
54 #define SERIAL_AMBA_MAJOR 204
55 #define SERIAL_AMBA_MINOR 16
56 #define SERIAL_AMBA_NR UART_NR
58 #define AMBA_ISR_PASS_LIMIT 256
60 #define UART_RX_DATA(s) (((s) & UART01x_FR_RXFE) == 0)
61 #define UART_TX_READY(s) (((s) & UART01x_FR_TXFF) == 0)
63 #define UART_DUMMY_RSR_RX 256
64 #define UART_PORT_SIZE 64
67 * We wrap our port structure around the generic uart_port.
69 struct uart_amba_port
{
70 struct uart_port port
;
72 struct amba_device
*dev
;
73 struct amba_pl010_data
*data
;
74 unsigned int old_status
;
77 static void pl010_stop_tx(struct uart_port
*port
)
79 struct uart_amba_port
*uap
= (struct uart_amba_port
*)port
;
82 cr
= readb(uap
->port
.membase
+ UART010_CR
);
83 cr
&= ~UART010_CR_TIE
;
84 writel(cr
, uap
->port
.membase
+ UART010_CR
);
87 static void pl010_start_tx(struct uart_port
*port
)
89 struct uart_amba_port
*uap
= (struct uart_amba_port
*)port
;
92 cr
= readb(uap
->port
.membase
+ UART010_CR
);
94 writel(cr
, uap
->port
.membase
+ UART010_CR
);
97 static void pl010_stop_rx(struct uart_port
*port
)
99 struct uart_amba_port
*uap
= (struct uart_amba_port
*)port
;
102 cr
= readb(uap
->port
.membase
+ UART010_CR
);
103 cr
&= ~(UART010_CR_RIE
| UART010_CR_RTIE
);
104 writel(cr
, uap
->port
.membase
+ UART010_CR
);
107 static void pl010_enable_ms(struct uart_port
*port
)
109 struct uart_amba_port
*uap
= (struct uart_amba_port
*)port
;
112 cr
= readb(uap
->port
.membase
+ UART010_CR
);
113 cr
|= UART010_CR_MSIE
;
114 writel(cr
, uap
->port
.membase
+ UART010_CR
);
117 static void pl010_rx_chars(struct uart_amba_port
*uap
)
119 struct tty_struct
*tty
= uap
->port
.state
->port
.tty
;
120 unsigned int status
, ch
, flag
, rsr
, max_count
= 256;
122 status
= readb(uap
->port
.membase
+ UART01x_FR
);
123 while (UART_RX_DATA(status
) && max_count
--) {
124 ch
= readb(uap
->port
.membase
+ UART01x_DR
);
127 uap
->port
.icount
.rx
++;
130 * Note that the error handling code is
131 * out of the main execution path
133 rsr
= readb(uap
->port
.membase
+ UART01x_RSR
) | UART_DUMMY_RSR_RX
;
134 if (unlikely(rsr
& UART01x_RSR_ANY
)) {
135 writel(0, uap
->port
.membase
+ UART01x_ECR
);
137 if (rsr
& UART01x_RSR_BE
) {
138 rsr
&= ~(UART01x_RSR_FE
| UART01x_RSR_PE
);
139 uap
->port
.icount
.brk
++;
140 if (uart_handle_break(&uap
->port
))
142 } else if (rsr
& UART01x_RSR_PE
)
143 uap
->port
.icount
.parity
++;
144 else if (rsr
& UART01x_RSR_FE
)
145 uap
->port
.icount
.frame
++;
146 if (rsr
& UART01x_RSR_OE
)
147 uap
->port
.icount
.overrun
++;
149 rsr
&= uap
->port
.read_status_mask
;
151 if (rsr
& UART01x_RSR_BE
)
153 else if (rsr
& UART01x_RSR_PE
)
155 else if (rsr
& UART01x_RSR_FE
)
159 if (uart_handle_sysrq_char(&uap
->port
, ch
))
162 uart_insert_char(&uap
->port
, rsr
, UART01x_RSR_OE
, ch
, flag
);
165 status
= readb(uap
->port
.membase
+ UART01x_FR
);
167 spin_unlock(&uap
->port
.lock
);
168 tty_flip_buffer_push(tty
);
169 spin_lock(&uap
->port
.lock
);
172 static void pl010_tx_chars(struct uart_amba_port
*uap
)
174 struct circ_buf
*xmit
= &uap
->port
.state
->xmit
;
177 if (uap
->port
.x_char
) {
178 writel(uap
->port
.x_char
, uap
->port
.membase
+ UART01x_DR
);
179 uap
->port
.icount
.tx
++;
180 uap
->port
.x_char
= 0;
183 if (uart_circ_empty(xmit
) || uart_tx_stopped(&uap
->port
)) {
184 pl010_stop_tx(&uap
->port
);
188 count
= uap
->port
.fifosize
>> 1;
190 writel(xmit
->buf
[xmit
->tail
], uap
->port
.membase
+ UART01x_DR
);
191 xmit
->tail
= (xmit
->tail
+ 1) & (UART_XMIT_SIZE
- 1);
192 uap
->port
.icount
.tx
++;
193 if (uart_circ_empty(xmit
))
195 } while (--count
> 0);
197 if (uart_circ_chars_pending(xmit
) < WAKEUP_CHARS
)
198 uart_write_wakeup(&uap
->port
);
200 if (uart_circ_empty(xmit
))
201 pl010_stop_tx(&uap
->port
);
204 static void pl010_modem_status(struct uart_amba_port
*uap
)
206 unsigned int status
, delta
;
208 writel(0, uap
->port
.membase
+ UART010_ICR
);
210 status
= readb(uap
->port
.membase
+ UART01x_FR
) & UART01x_FR_MODEM_ANY
;
212 delta
= status
^ uap
->old_status
;
213 uap
->old_status
= status
;
218 if (delta
& UART01x_FR_DCD
)
219 uart_handle_dcd_change(&uap
->port
, status
& UART01x_FR_DCD
);
221 if (delta
& UART01x_FR_DSR
)
222 uap
->port
.icount
.dsr
++;
224 if (delta
& UART01x_FR_CTS
)
225 uart_handle_cts_change(&uap
->port
, status
& UART01x_FR_CTS
);
227 wake_up_interruptible(&uap
->port
.state
->port
.delta_msr_wait
);
230 static irqreturn_t
pl010_int(int irq
, void *dev_id
)
232 struct uart_amba_port
*uap
= dev_id
;
233 unsigned int status
, pass_counter
= AMBA_ISR_PASS_LIMIT
;
236 spin_lock(&uap
->port
.lock
);
238 status
= readb(uap
->port
.membase
+ UART010_IIR
);
241 if (status
& (UART010_IIR_RTIS
| UART010_IIR_RIS
))
243 if (status
& UART010_IIR_MIS
)
244 pl010_modem_status(uap
);
245 if (status
& UART010_IIR_TIS
)
248 if (pass_counter
-- == 0)
251 status
= readb(uap
->port
.membase
+ UART010_IIR
);
252 } while (status
& (UART010_IIR_RTIS
| UART010_IIR_RIS
|
257 spin_unlock(&uap
->port
.lock
);
259 return IRQ_RETVAL(handled
);
262 static unsigned int pl010_tx_empty(struct uart_port
*port
)
264 struct uart_amba_port
*uap
= (struct uart_amba_port
*)port
;
265 unsigned int status
= readb(uap
->port
.membase
+ UART01x_FR
);
266 return status
& UART01x_FR_BUSY
? 0 : TIOCSER_TEMT
;
269 static unsigned int pl010_get_mctrl(struct uart_port
*port
)
271 struct uart_amba_port
*uap
= (struct uart_amba_port
*)port
;
272 unsigned int result
= 0;
275 status
= readb(uap
->port
.membase
+ UART01x_FR
);
276 if (status
& UART01x_FR_DCD
)
278 if (status
& UART01x_FR_DSR
)
280 if (status
& UART01x_FR_CTS
)
286 static void pl010_set_mctrl(struct uart_port
*port
, unsigned int mctrl
)
288 struct uart_amba_port
*uap
= (struct uart_amba_port
*)port
;
291 uap
->data
->set_mctrl(uap
->dev
, uap
->port
.membase
, mctrl
);
294 static void pl010_break_ctl(struct uart_port
*port
, int break_state
)
296 struct uart_amba_port
*uap
= (struct uart_amba_port
*)port
;
300 spin_lock_irqsave(&uap
->port
.lock
, flags
);
301 lcr_h
= readb(uap
->port
.membase
+ UART010_LCRH
);
302 if (break_state
== -1)
303 lcr_h
|= UART01x_LCRH_BRK
;
305 lcr_h
&= ~UART01x_LCRH_BRK
;
306 writel(lcr_h
, uap
->port
.membase
+ UART010_LCRH
);
307 spin_unlock_irqrestore(&uap
->port
.lock
, flags
);
310 static int pl010_startup(struct uart_port
*port
)
312 struct uart_amba_port
*uap
= (struct uart_amba_port
*)port
;
316 * Try to enable the clock producer.
318 retval
= clk_enable(uap
->clk
);
322 uap
->port
.uartclk
= clk_get_rate(uap
->clk
);
327 retval
= request_irq(uap
->port
.irq
, pl010_int
, 0, "uart-pl010", uap
);
332 * initialise the old status of the modem signals
334 uap
->old_status
= readb(uap
->port
.membase
+ UART01x_FR
) & UART01x_FR_MODEM_ANY
;
337 * Finally, enable interrupts
339 writel(UART01x_CR_UARTEN
| UART010_CR_RIE
| UART010_CR_RTIE
,
340 uap
->port
.membase
+ UART010_CR
);
345 clk_disable(uap
->clk
);
350 static void pl010_shutdown(struct uart_port
*port
)
352 struct uart_amba_port
*uap
= (struct uart_amba_port
*)port
;
357 free_irq(uap
->port
.irq
, uap
);
360 * disable all interrupts, disable the port
362 writel(0, uap
->port
.membase
+ UART010_CR
);
364 /* disable break condition and fifos */
365 writel(readb(uap
->port
.membase
+ UART010_LCRH
) &
366 ~(UART01x_LCRH_BRK
| UART01x_LCRH_FEN
),
367 uap
->port
.membase
+ UART010_LCRH
);
370 * Shut down the clock producer
372 clk_disable(uap
->clk
);
376 pl010_set_termios(struct uart_port
*port
, struct ktermios
*termios
,
377 struct ktermios
*old
)
379 struct uart_amba_port
*uap
= (struct uart_amba_port
*)port
;
380 unsigned int lcr_h
, old_cr
;
382 unsigned int baud
, quot
;
385 * Ask the core to calculate the divisor for us.
387 baud
= uart_get_baud_rate(port
, termios
, old
, 0, uap
->port
.uartclk
/16);
388 quot
= uart_get_divisor(port
, baud
);
390 switch (termios
->c_cflag
& CSIZE
) {
392 lcr_h
= UART01x_LCRH_WLEN_5
;
395 lcr_h
= UART01x_LCRH_WLEN_6
;
398 lcr_h
= UART01x_LCRH_WLEN_7
;
401 lcr_h
= UART01x_LCRH_WLEN_8
;
404 if (termios
->c_cflag
& CSTOPB
)
405 lcr_h
|= UART01x_LCRH_STP2
;
406 if (termios
->c_cflag
& PARENB
) {
407 lcr_h
|= UART01x_LCRH_PEN
;
408 if (!(termios
->c_cflag
& PARODD
))
409 lcr_h
|= UART01x_LCRH_EPS
;
411 if (uap
->port
.fifosize
> 1)
412 lcr_h
|= UART01x_LCRH_FEN
;
414 spin_lock_irqsave(&uap
->port
.lock
, flags
);
417 * Update the per-port timeout.
419 uart_update_timeout(port
, termios
->c_cflag
, baud
);
421 uap
->port
.read_status_mask
= UART01x_RSR_OE
;
422 if (termios
->c_iflag
& INPCK
)
423 uap
->port
.read_status_mask
|= UART01x_RSR_FE
| UART01x_RSR_PE
;
424 if (termios
->c_iflag
& (BRKINT
| PARMRK
))
425 uap
->port
.read_status_mask
|= UART01x_RSR_BE
;
428 * Characters to ignore
430 uap
->port
.ignore_status_mask
= 0;
431 if (termios
->c_iflag
& IGNPAR
)
432 uap
->port
.ignore_status_mask
|= UART01x_RSR_FE
| UART01x_RSR_PE
;
433 if (termios
->c_iflag
& IGNBRK
) {
434 uap
->port
.ignore_status_mask
|= UART01x_RSR_BE
;
436 * If we're ignoring parity and break indicators,
437 * ignore overruns too (for real raw support).
439 if (termios
->c_iflag
& IGNPAR
)
440 uap
->port
.ignore_status_mask
|= UART01x_RSR_OE
;
444 * Ignore all characters if CREAD is not set.
446 if ((termios
->c_cflag
& CREAD
) == 0)
447 uap
->port
.ignore_status_mask
|= UART_DUMMY_RSR_RX
;
449 /* first, disable everything */
450 old_cr
= readb(uap
->port
.membase
+ UART010_CR
) & ~UART010_CR_MSIE
;
452 if (UART_ENABLE_MS(port
, termios
->c_cflag
))
453 old_cr
|= UART010_CR_MSIE
;
455 writel(0, uap
->port
.membase
+ UART010_CR
);
459 writel((quot
& 0xf00) >> 8, uap
->port
.membase
+ UART010_LCRM
);
460 writel(quot
& 0xff, uap
->port
.membase
+ UART010_LCRL
);
463 * ----------v----------v----------v----------v-----
464 * NOTE: MUST BE WRITTEN AFTER UARTLCR_M & UARTLCR_L
465 * ----------^----------^----------^----------^-----
467 writel(lcr_h
, uap
->port
.membase
+ UART010_LCRH
);
468 writel(old_cr
, uap
->port
.membase
+ UART010_CR
);
470 spin_unlock_irqrestore(&uap
->port
.lock
, flags
);
473 static void pl010_set_ldisc(struct uart_port
*port
, int new)
476 port
->flags
|= UPF_HARDPPS_CD
;
477 pl010_enable_ms(port
);
479 port
->flags
&= ~UPF_HARDPPS_CD
;
482 static const char *pl010_type(struct uart_port
*port
)
484 return port
->type
== PORT_AMBA
? "AMBA" : NULL
;
488 * Release the memory region(s) being used by 'port'
490 static void pl010_release_port(struct uart_port
*port
)
492 release_mem_region(port
->mapbase
, UART_PORT_SIZE
);
496 * Request the memory region(s) being used by 'port'
498 static int pl010_request_port(struct uart_port
*port
)
500 return request_mem_region(port
->mapbase
, UART_PORT_SIZE
, "uart-pl010")
501 != NULL
? 0 : -EBUSY
;
505 * Configure/autoconfigure the port.
507 static void pl010_config_port(struct uart_port
*port
, int flags
)
509 if (flags
& UART_CONFIG_TYPE
) {
510 port
->type
= PORT_AMBA
;
511 pl010_request_port(port
);
516 * verify the new serial_struct (for TIOCSSERIAL).
518 static int pl010_verify_port(struct uart_port
*port
, struct serial_struct
*ser
)
521 if (ser
->type
!= PORT_UNKNOWN
&& ser
->type
!= PORT_AMBA
)
523 if (ser
->irq
< 0 || ser
->irq
>= nr_irqs
)
525 if (ser
->baud_base
< 9600)
530 static struct uart_ops amba_pl010_pops
= {
531 .tx_empty
= pl010_tx_empty
,
532 .set_mctrl
= pl010_set_mctrl
,
533 .get_mctrl
= pl010_get_mctrl
,
534 .stop_tx
= pl010_stop_tx
,
535 .start_tx
= pl010_start_tx
,
536 .stop_rx
= pl010_stop_rx
,
537 .enable_ms
= pl010_enable_ms
,
538 .break_ctl
= pl010_break_ctl
,
539 .startup
= pl010_startup
,
540 .shutdown
= pl010_shutdown
,
541 .set_termios
= pl010_set_termios
,
542 .set_ldisc
= pl010_set_ldisc
,
544 .release_port
= pl010_release_port
,
545 .request_port
= pl010_request_port
,
546 .config_port
= pl010_config_port
,
547 .verify_port
= pl010_verify_port
,
550 static struct uart_amba_port
*amba_ports
[UART_NR
];
552 #ifdef CONFIG_SERIAL_AMBA_PL010_CONSOLE
554 static void pl010_console_putchar(struct uart_port
*port
, int ch
)
556 struct uart_amba_port
*uap
= (struct uart_amba_port
*)port
;
560 status
= readb(uap
->port
.membase
+ UART01x_FR
);
562 } while (!UART_TX_READY(status
));
563 writel(ch
, uap
->port
.membase
+ UART01x_DR
);
567 pl010_console_write(struct console
*co
, const char *s
, unsigned int count
)
569 struct uart_amba_port
*uap
= amba_ports
[co
->index
];
570 unsigned int status
, old_cr
;
572 clk_enable(uap
->clk
);
575 * First save the CR then disable the interrupts
577 old_cr
= readb(uap
->port
.membase
+ UART010_CR
);
578 writel(UART01x_CR_UARTEN
, uap
->port
.membase
+ UART010_CR
);
580 uart_console_write(&uap
->port
, s
, count
, pl010_console_putchar
);
583 * Finally, wait for transmitter to become empty
584 * and restore the TCR
587 status
= readb(uap
->port
.membase
+ UART01x_FR
);
589 } while (status
& UART01x_FR_BUSY
);
590 writel(old_cr
, uap
->port
.membase
+ UART010_CR
);
592 clk_disable(uap
->clk
);
596 pl010_console_get_options(struct uart_amba_port
*uap
, int *baud
,
597 int *parity
, int *bits
)
599 if (readb(uap
->port
.membase
+ UART010_CR
) & UART01x_CR_UARTEN
) {
600 unsigned int lcr_h
, quot
;
601 lcr_h
= readb(uap
->port
.membase
+ UART010_LCRH
);
604 if (lcr_h
& UART01x_LCRH_PEN
) {
605 if (lcr_h
& UART01x_LCRH_EPS
)
611 if ((lcr_h
& 0x60) == UART01x_LCRH_WLEN_7
)
616 quot
= readb(uap
->port
.membase
+ UART010_LCRL
) |
617 readb(uap
->port
.membase
+ UART010_LCRM
) << 8;
618 *baud
= uap
->port
.uartclk
/ (16 * (quot
+ 1));
622 static int __init
pl010_console_setup(struct console
*co
, char *options
)
624 struct uart_amba_port
*uap
;
631 * Check whether an invalid uart number has been specified, and
632 * if so, search for the first available port that does have
635 if (co
->index
>= UART_NR
)
637 uap
= amba_ports
[co
->index
];
641 uap
->port
.uartclk
= clk_get_rate(uap
->clk
);
644 uart_parse_options(options
, &baud
, &parity
, &bits
, &flow
);
646 pl010_console_get_options(uap
, &baud
, &parity
, &bits
);
648 return uart_set_options(&uap
->port
, co
, baud
, parity
, bits
, flow
);
651 static struct uart_driver amba_reg
;
652 static struct console amba_console
= {
654 .write
= pl010_console_write
,
655 .device
= uart_console_device
,
656 .setup
= pl010_console_setup
,
657 .flags
= CON_PRINTBUFFER
,
662 #define AMBA_CONSOLE &amba_console
664 #define AMBA_CONSOLE NULL
667 static struct uart_driver amba_reg
= {
668 .owner
= THIS_MODULE
,
669 .driver_name
= "ttyAM",
671 .major
= SERIAL_AMBA_MAJOR
,
672 .minor
= SERIAL_AMBA_MINOR
,
674 .cons
= AMBA_CONSOLE
,
677 static int pl010_probe(struct amba_device
*dev
, const struct amba_id
*id
)
679 struct uart_amba_port
*uap
;
683 for (i
= 0; i
< ARRAY_SIZE(amba_ports
); i
++)
684 if (amba_ports
[i
] == NULL
)
687 if (i
== ARRAY_SIZE(amba_ports
)) {
692 uap
= kzalloc(sizeof(struct uart_amba_port
), GFP_KERNEL
);
698 base
= ioremap(dev
->res
.start
, resource_size(&dev
->res
));
704 uap
->clk
= clk_get(&dev
->dev
, NULL
);
705 if (IS_ERR(uap
->clk
)) {
706 ret
= PTR_ERR(uap
->clk
);
710 uap
->port
.dev
= &dev
->dev
;
711 uap
->port
.mapbase
= dev
->res
.start
;
712 uap
->port
.membase
= base
;
713 uap
->port
.iotype
= UPIO_MEM
;
714 uap
->port
.irq
= dev
->irq
[0];
715 uap
->port
.fifosize
= 16;
716 uap
->port
.ops
= &amba_pl010_pops
;
717 uap
->port
.flags
= UPF_BOOT_AUTOCONF
;
720 uap
->data
= dev
->dev
.platform_data
;
724 amba_set_drvdata(dev
, uap
);
725 ret
= uart_add_one_port(&amba_reg
, &uap
->port
);
727 amba_set_drvdata(dev
, NULL
);
728 amba_ports
[i
] = NULL
;
739 static int pl010_remove(struct amba_device
*dev
)
741 struct uart_amba_port
*uap
= amba_get_drvdata(dev
);
744 amba_set_drvdata(dev
, NULL
);
746 uart_remove_one_port(&amba_reg
, &uap
->port
);
748 for (i
= 0; i
< ARRAY_SIZE(amba_ports
); i
++)
749 if (amba_ports
[i
] == uap
)
750 amba_ports
[i
] = NULL
;
752 iounmap(uap
->port
.membase
);
758 static int pl010_suspend(struct amba_device
*dev
, pm_message_t state
)
760 struct uart_amba_port
*uap
= amba_get_drvdata(dev
);
763 uart_suspend_port(&amba_reg
, &uap
->port
);
768 static int pl010_resume(struct amba_device
*dev
)
770 struct uart_amba_port
*uap
= amba_get_drvdata(dev
);
773 uart_resume_port(&amba_reg
, &uap
->port
);
778 static struct amba_id pl010_ids
[] = {
786 static struct amba_driver pl010_driver
= {
788 .name
= "uart-pl010",
790 .id_table
= pl010_ids
,
791 .probe
= pl010_probe
,
792 .remove
= pl010_remove
,
793 .suspend
= pl010_suspend
,
794 .resume
= pl010_resume
,
797 static int __init
pl010_init(void)
801 printk(KERN_INFO
"Serial: AMBA driver\n");
803 ret
= uart_register_driver(&amba_reg
);
805 ret
= amba_driver_register(&pl010_driver
);
807 uart_unregister_driver(&amba_reg
);
812 static void __exit
pl010_exit(void)
814 amba_driver_unregister(&pl010_driver
);
815 uart_unregister_driver(&amba_reg
);
818 module_init(pl010_init
);
819 module_exit(pl010_exit
);
821 MODULE_AUTHOR("ARM Ltd/Deep Blue Solutions Ltd");
822 MODULE_DESCRIPTION("ARM AMBA serial port driver");
823 MODULE_LICENSE("GPL");