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Linux/drivers/tty/serial/arc_uart.c

  1 /*
  2  * ARC On-Chip(fpga) UART Driver
  3  *
  4  * Copyright (C) 2010-2012 Synopsys, Inc. (www.synopsys.com)
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License version 2 as
  8  * published by the Free Software Foundation.
  9  *
 10  * vineetg: July 10th 2012
 11  *  -Decoupled the driver from arch/arc
 12  *    +Using platform_get_resource() for irq/membase (thx to bfin_uart.c)
 13  *    +Using early_platform_xxx() for early console (thx to mach-shmobile/xxx)
 14  *
 15  * Vineetg: Aug 21st 2010
 16  *  -Is uart_tx_stopped() not done in tty write path as it has already been
 17  *   taken care of, in serial core
 18  *
 19  * Vineetg: Aug 18th 2010
 20  *  -New Serial Core based ARC UART driver
 21  *  -Derived largely from blackfin driver albiet with some major tweaks
 22  *
 23  * TODO:
 24  *  -check if sysreq works
 25  */
 26 
 27 #if defined(CONFIG_SERIAL_ARC_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
 28 #define SUPPORT_SYSRQ
 29 #endif
 30 
 31 #include <linux/module.h>
 32 #include <linux/serial.h>
 33 #include <linux/console.h>
 34 #include <linux/sysrq.h>
 35 #include <linux/platform_device.h>
 36 #include <linux/tty.h>
 37 #include <linux/tty_flip.h>
 38 #include <linux/serial_core.h>
 39 #include <linux/io.h>
 40 #include <linux/of.h>
 41 #include <linux/of_platform.h>
 42 
 43 /*************************************
 44  * ARC UART Hardware Specs
 45  ************************************/
 46 #define ARC_UART_TX_FIFO_SIZE  1
 47 
 48 /*
 49  * UART Register set (this is not a Standards Compliant IP)
 50  * Also each reg is Word aligned, but only 8 bits wide
 51  */
 52 #define R_ID0   0
 53 #define R_ID1   4
 54 #define R_ID2   8
 55 #define R_ID3   12
 56 #define R_DATA  16
 57 #define R_STS   20
 58 #define R_BAUDL 24
 59 #define R_BAUDH 28
 60 
 61 /* Bits for UART Status Reg (R/W) */
 62 #define RXIENB  0x04    /* Receive Interrupt Enable */
 63 #define TXIENB  0x40    /* Transmit Interrupt Enable */
 64 
 65 #define RXEMPTY 0x20    /* Receive FIFO Empty: No char receivede */
 66 #define TXEMPTY 0x80    /* Transmit FIFO Empty, thus char can be written into */
 67 
 68 #define RXFULL  0x08    /* Receive FIFO full */
 69 #define RXFULL1 0x10    /* Receive FIFO has space for 1 char (tot space=4) */
 70 
 71 #define RXFERR  0x01    /* Frame Error: Stop Bit not detected */
 72 #define RXOERR  0x02    /* OverFlow Err: Char recv but RXFULL still set */
 73 
 74 /* Uart bit fiddling helpers: lowest level */
 75 #define RBASE(uart, reg)      (uart->port.membase + reg)
 76 #define UART_REG_SET(u, r, v) writeb((v), RBASE(u, r))
 77 #define UART_REG_GET(u, r)    readb(RBASE(u, r))
 78 
 79 #define UART_REG_OR(u, r, v)  UART_REG_SET(u, r, UART_REG_GET(u, r) | (v))
 80 #define UART_REG_CLR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) & ~(v))
 81 
 82 /* Uart bit fiddling helpers: API level */
 83 #define UART_SET_DATA(uart, val)   UART_REG_SET(uart, R_DATA, val)
 84 #define UART_GET_DATA(uart)        UART_REG_GET(uart, R_DATA)
 85 
 86 #define UART_SET_BAUDH(uart, val)  UART_REG_SET(uart, R_BAUDH, val)
 87 #define UART_SET_BAUDL(uart, val)  UART_REG_SET(uart, R_BAUDL, val)
 88 
 89 #define UART_CLR_STATUS(uart, val) UART_REG_CLR(uart, R_STS, val)
 90 #define UART_GET_STATUS(uart)      UART_REG_GET(uart, R_STS)
 91 
 92 #define UART_ALL_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB|TXIENB)
 93 #define UART_RX_IRQ_DISABLE(uart)  UART_REG_CLR(uart, R_STS, RXIENB)
 94 #define UART_TX_IRQ_DISABLE(uart)  UART_REG_CLR(uart, R_STS, TXIENB)
 95 
 96 #define UART_ALL_IRQ_ENABLE(uart)  UART_REG_OR(uart, R_STS, RXIENB|TXIENB)
 97 #define UART_RX_IRQ_ENABLE(uart)   UART_REG_OR(uart, R_STS, RXIENB)
 98 #define UART_TX_IRQ_ENABLE(uart)   UART_REG_OR(uart, R_STS, TXIENB)
 99 
100 #define ARC_SERIAL_DEV_NAME     "ttyARC"
101 
102 struct arc_uart_port {
103         struct uart_port port;
104         unsigned long baud;
105         int is_emulated;        /* H/w vs. Instruction Set Simulator */
106 };
107 
108 #define to_arc_port(uport)  container_of(uport, struct arc_uart_port, port)
109 
110 static struct arc_uart_port arc_uart_ports[CONFIG_SERIAL_ARC_NR_PORTS];
111 
112 #ifdef CONFIG_SERIAL_ARC_CONSOLE
113 static struct console arc_console;
114 #endif
115 
116 #define DRIVER_NAME     "arc-uart"
117 
118 static struct uart_driver arc_uart_driver = {
119         .owner          = THIS_MODULE,
120         .driver_name    = DRIVER_NAME,
121         .dev_name       = ARC_SERIAL_DEV_NAME,
122         .major          = 0,
123         .minor          = 0,
124         .nr             = CONFIG_SERIAL_ARC_NR_PORTS,
125 #ifdef CONFIG_SERIAL_ARC_CONSOLE
126         .cons           = &arc_console,
127 #endif
128 };
129 
130 static void arc_serial_stop_rx(struct uart_port *port)
131 {
132         struct arc_uart_port *uart = to_arc_port(port);
133 
134         UART_RX_IRQ_DISABLE(uart);
135 }
136 
137 static void arc_serial_stop_tx(struct uart_port *port)
138 {
139         struct arc_uart_port *uart = to_arc_port(port);
140 
141         while (!(UART_GET_STATUS(uart) & TXEMPTY))
142                 cpu_relax();
143 
144         UART_TX_IRQ_DISABLE(uart);
145 }
146 
147 /*
148  * Return TIOCSER_TEMT when transmitter is not busy.
149  */
150 static unsigned int arc_serial_tx_empty(struct uart_port *port)
151 {
152         struct arc_uart_port *uart = to_arc_port(port);
153         unsigned int stat;
154 
155         stat = UART_GET_STATUS(uart);
156         if (stat & TXEMPTY)
157                 return TIOCSER_TEMT;
158 
159         return 0;
160 }
161 
162 /*
163  * Driver internal routine, used by both tty(serial core) as well as tx-isr
164  *  -Called under spinlock in either cases
165  *  -also tty->stopped has already been checked
166  *     = by uart_start( ) before calling us
167  *     = tx_ist checks that too before calling
168  */
169 static void arc_serial_tx_chars(struct arc_uart_port *uart)
170 {
171         struct circ_buf *xmit = &uart->port.state->xmit;
172         int sent = 0;
173         unsigned char ch;
174 
175         if (unlikely(uart->port.x_char)) {
176                 UART_SET_DATA(uart, uart->port.x_char);
177                 uart->port.icount.tx++;
178                 uart->port.x_char = 0;
179                 sent = 1;
180         } else if (!uart_circ_empty(xmit)) {
181                 ch = xmit->buf[xmit->tail];
182                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
183                 uart->port.icount.tx++;
184                 while (!(UART_GET_STATUS(uart) & TXEMPTY))
185                         cpu_relax();
186                 UART_SET_DATA(uart, ch);
187                 sent = 1;
188         }
189 
190         /*
191          * If num chars in xmit buffer are too few, ask tty layer for more.
192          * By Hard ISR to schedule processing in software interrupt part
193          */
194         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
195                 uart_write_wakeup(&uart->port);
196 
197         if (sent)
198                 UART_TX_IRQ_ENABLE(uart);
199 }
200 
201 /*
202  * port is locked and interrupts are disabled
203  * uart_start( ) calls us under the port spinlock irqsave
204  */
205 static void arc_serial_start_tx(struct uart_port *port)
206 {
207         struct arc_uart_port *uart = to_arc_port(port);
208 
209         arc_serial_tx_chars(uart);
210 }
211 
212 static void arc_serial_rx_chars(struct arc_uart_port *uart, unsigned int status)
213 {
214         unsigned int ch, flg = 0;
215 
216         /*
217          * UART has 4 deep RX-FIFO. Driver's recongnition of this fact
218          * is very subtle. Here's how ...
219          * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,
220          * driver reads the DATA Reg and keeps doing that in a loop, until
221          * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,
222          * before RX-EMPTY=0, implies some sort of buffering going on in the
223          * controller, which is indeed the Rx-FIFO.
224          */
225         do {
226                 /*
227                  * This could be an Rx Intr for err (no data),
228                  * so check err and clear that Intr first
229                  */
230                 if (unlikely(status & (RXOERR | RXFERR))) {
231                         if (status & RXOERR) {
232                                 uart->port.icount.overrun++;
233                                 flg = TTY_OVERRUN;
234                                 UART_CLR_STATUS(uart, RXOERR);
235                         }
236 
237                         if (status & RXFERR) {
238                                 uart->port.icount.frame++;
239                                 flg = TTY_FRAME;
240                                 UART_CLR_STATUS(uart, RXFERR);
241                         }
242                 } else
243                         flg = TTY_NORMAL;
244 
245                 if (status & RXEMPTY)
246                         continue;
247 
248                 ch = UART_GET_DATA(uart);
249                 uart->port.icount.rx++;
250 
251                 if (!(uart_handle_sysrq_char(&uart->port, ch)))
252                         uart_insert_char(&uart->port, status, RXOERR, ch, flg);
253 
254                 spin_unlock(&uart->port.lock);
255                 tty_flip_buffer_push(&uart->port.state->port);
256                 spin_lock(&uart->port.lock);
257         } while (!((status = UART_GET_STATUS(uart)) & RXEMPTY));
258 }
259 
260 /*
261  * A note on the Interrupt handling state machine of this driver
262  *
263  * kernel printk writes funnel thru the console driver framework and in order
264  * to keep things simple as well as efficient, it writes to UART in polled
265  * mode, in one shot, and exits.
266  *
267  * OTOH, Userland output (via tty layer), uses interrupt based writes as there
268  * can be undeterministic delay between char writes.
269  *
270  * Thus Rx-interrupts are always enabled, while tx-interrupts are by default
271  * disabled.
272  *
273  * When tty has some data to send out, serial core calls driver's start_tx
274  * which
275  *   -checks-if-tty-buffer-has-char-to-send
276  *   -writes-data-to-uart
277  *   -enable-tx-intr
278  *
279  * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
280  * The first thing Tx ISR does is disable further Tx interrupts (as this could
281  * be the last char to send, before settling down into the quiet polled mode).
282  * It then calls the exact routine used by tty layer write to send out any
283  * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
284  * of no data, it remains disabled.
285  * This is how the transmit state machine is dynamically switched on/off
286  */
287 
288 static irqreturn_t arc_serial_isr(int irq, void *dev_id)
289 {
290         struct arc_uart_port *uart = dev_id;
291         unsigned int status;
292 
293         status = UART_GET_STATUS(uart);
294 
295         /*
296          * Single IRQ for both Rx (data available) Tx (room available) Interrupt
297          * notifications from the UART Controller.
298          * To demultiplex between the two, we check the relevant bits
299          */
300         if (status & RXIENB) {
301 
302                 /* already in ISR, no need of xx_irqsave */
303                 spin_lock(&uart->port.lock);
304                 arc_serial_rx_chars(uart, status);
305                 spin_unlock(&uart->port.lock);
306         }
307 
308         if ((status & TXIENB) && (status & TXEMPTY)) {
309 
310                 /* Unconditionally disable further Tx-Interrupts.
311                  * will be enabled by tx_chars() if needed.
312                  */
313                 UART_TX_IRQ_DISABLE(uart);
314 
315                 spin_lock(&uart->port.lock);
316 
317                 if (!uart_tx_stopped(&uart->port))
318                         arc_serial_tx_chars(uart);
319 
320                 spin_unlock(&uart->port.lock);
321         }
322 
323         return IRQ_HANDLED;
324 }
325 
326 static unsigned int arc_serial_get_mctrl(struct uart_port *port)
327 {
328         /*
329          * Pretend we have a Modem status reg and following bits are
330          *  always set, to satify the serial core state machine
331          *  (DSR) Data Set Ready
332          *  (CTS) Clear To Send
333          *  (CAR) Carrier Detect
334          */
335         return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
336 }
337 
338 static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
339 {
340         /* MCR not present */
341 }
342 
343 /* Enable Modem Status Interrupts */
344 
345 static void arc_serial_enable_ms(struct uart_port *port)
346 {
347         /* MSR not present */
348 }
349 
350 static void arc_serial_break_ctl(struct uart_port *port, int break_state)
351 {
352         /* ARC UART doesn't support sending Break signal */
353 }
354 
355 static int arc_serial_startup(struct uart_port *port)
356 {
357         struct arc_uart_port *uart = to_arc_port(port);
358 
359         /* Before we hook up the ISR, Disable all UART Interrupts */
360         UART_ALL_IRQ_DISABLE(uart);
361 
362         if (request_irq(uart->port.irq, arc_serial_isr, 0, "arc uart rx-tx",
363                         uart)) {
364                 dev_warn(uart->port.dev, "Unable to attach ARC UART intr\n");
365                 return -EBUSY;
366         }
367 
368         UART_RX_IRQ_ENABLE(uart); /* Only Rx IRQ enabled to begin with */
369 
370         return 0;
371 }
372 
373 /* This is not really needed */
374 static void arc_serial_shutdown(struct uart_port *port)
375 {
376         struct arc_uart_port *uart = to_arc_port(port);
377         free_irq(uart->port.irq, uart);
378 }
379 
380 static void
381 arc_serial_set_termios(struct uart_port *port, struct ktermios *new,
382                        struct ktermios *old)
383 {
384         struct arc_uart_port *uart = to_arc_port(port);
385         unsigned int baud, uartl, uarth, hw_val;
386         unsigned long flags;
387 
388         /*
389          * Use the generic handler so that any specially encoded baud rates
390          * such as SPD_xx flags or "%B0" can be handled
391          * Max Baud I suppose will not be more than current 115K * 4
392          * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)
393          * spread over two 8-bit registers
394          */
395         baud = uart_get_baud_rate(port, new, old, 0, 460800);
396 
397         hw_val = port->uartclk / (uart->baud * 4) - 1;
398         uartl = hw_val & 0xFF;
399         uarth = (hw_val >> 8) & 0xFF;
400 
401         /*
402          * UART ISS(Instruction Set simulator) emulation has a subtle bug:
403          * A existing value of Baudh = 0 is used as a indication to startup
404          * it's internal state machine.
405          * Thus if baudh is set to 0, 2 times, it chokes.
406          * This happens with BAUD=115200 and the formaula above
407          * Until that is fixed, when running on ISS, we will set baudh to !0
408          */
409         if (uart->is_emulated)
410                 uarth = 1;
411 
412         spin_lock_irqsave(&port->lock, flags);
413 
414         UART_ALL_IRQ_DISABLE(uart);
415 
416         UART_SET_BAUDL(uart, uartl);
417         UART_SET_BAUDH(uart, uarth);
418 
419         UART_RX_IRQ_ENABLE(uart);
420 
421         /*
422          * UART doesn't support Parity/Hardware Flow Control;
423          * Only supports 8N1 character size
424          */
425         new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);
426         new->c_cflag |= CS8;
427 
428         if (old)
429                 tty_termios_copy_hw(new, old);
430 
431         /* Don't rewrite B0 */
432         if (tty_termios_baud_rate(new))
433                 tty_termios_encode_baud_rate(new, baud, baud);
434 
435         uart_update_timeout(port, new->c_cflag, baud);
436 
437         spin_unlock_irqrestore(&port->lock, flags);
438 }
439 
440 static const char *arc_serial_type(struct uart_port *port)
441 {
442         struct arc_uart_port *uart = to_arc_port(port);
443 
444         return uart->port.type == PORT_ARC ? DRIVER_NAME : NULL;
445 }
446 
447 static void arc_serial_release_port(struct uart_port *port)
448 {
449 }
450 
451 static int arc_serial_request_port(struct uart_port *port)
452 {
453         return 0;
454 }
455 
456 /*
457  * Verify the new serial_struct (for TIOCSSERIAL).
458  */
459 static int
460 arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
461 {
462         if (port->type != PORT_UNKNOWN && ser->type != PORT_ARC)
463                 return -EINVAL;
464 
465         return 0;
466 }
467 
468 /*
469  * Configure/autoconfigure the port.
470  */
471 static void arc_serial_config_port(struct uart_port *port, int flags)
472 {
473         struct arc_uart_port *uart = to_arc_port(port);
474 
475         if (flags & UART_CONFIG_TYPE)
476                 uart->port.type = PORT_ARC;
477 }
478 
479 #if defined(CONFIG_CONSOLE_POLL) || defined(CONFIG_SERIAL_ARC_CONSOLE)
480 
481 static void arc_serial_poll_putchar(struct uart_port *port, unsigned char chr)
482 {
483         struct arc_uart_port *uart = to_arc_port(port);
484 
485         while (!(UART_GET_STATUS(uart) & TXEMPTY))
486                 cpu_relax();
487 
488         UART_SET_DATA(uart, chr);
489 }
490 #endif
491 
492 #ifdef CONFIG_CONSOLE_POLL
493 static int arc_serial_poll_getchar(struct uart_port *port)
494 {
495         struct arc_uart_port *uart = to_arc_port(port);
496         unsigned char chr;
497 
498         while (!(UART_GET_STATUS(uart) & RXEMPTY))
499                 cpu_relax();
500 
501         chr = UART_GET_DATA(uart);
502         return chr;
503 }
504 #endif
505 
506 static struct uart_ops arc_serial_pops = {
507         .tx_empty       = arc_serial_tx_empty,
508         .set_mctrl      = arc_serial_set_mctrl,
509         .get_mctrl      = arc_serial_get_mctrl,
510         .stop_tx        = arc_serial_stop_tx,
511         .start_tx       = arc_serial_start_tx,
512         .stop_rx        = arc_serial_stop_rx,
513         .enable_ms      = arc_serial_enable_ms,
514         .break_ctl      = arc_serial_break_ctl,
515         .startup        = arc_serial_startup,
516         .shutdown       = arc_serial_shutdown,
517         .set_termios    = arc_serial_set_termios,
518         .type           = arc_serial_type,
519         .release_port   = arc_serial_release_port,
520         .request_port   = arc_serial_request_port,
521         .config_port    = arc_serial_config_port,
522         .verify_port    = arc_serial_verify_port,
523 #ifdef CONFIG_CONSOLE_POLL
524         .poll_put_char = arc_serial_poll_putchar,
525         .poll_get_char = arc_serial_poll_getchar,
526 #endif
527 };
528 
529 static int
530 arc_uart_init_one(struct platform_device *pdev, int dev_id)
531 {
532         struct resource *res, *res2;
533         unsigned long *plat_data;
534         struct arc_uart_port *uart = &arc_uart_ports[dev_id];
535 
536         plat_data = dev_get_platdata(&pdev->dev);
537         if (!plat_data)
538                 return -ENODEV;
539 
540         uart->is_emulated = !!plat_data[0];     /* workaround ISS bug */
541 
542         if (is_early_platform_device(pdev)) {
543                 uart->port.uartclk = plat_data[1];
544                 uart->baud = plat_data[2];
545         } else {
546                 struct device_node *np = pdev->dev.of_node;
547                 u32 val;
548 
549                 if (of_property_read_u32(np, "clock-frequency", &val)) {
550                         dev_err(&pdev->dev, "clock-frequency property NOTset\n");
551                         return -EINVAL;
552                 }
553                 uart->port.uartclk = val;
554 
555                 if (of_property_read_u32(np, "current-speed", &val)) {
556                         dev_err(&pdev->dev, "current-speed property NOT set\n");
557                         return -EINVAL;
558                 }
559                 uart->baud = val;
560         }
561 
562         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
563         if (!res)
564                 return -ENODEV;
565 
566         res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
567         if (!res2)
568                 return -ENODEV;
569 
570         uart->port.mapbase = res->start;
571         uart->port.membase = ioremap_nocache(res->start, resource_size(res));
572         if (!uart->port.membase)
573                 /* No point of dev_err since UART itself is hosed here */
574                 return -ENXIO;
575 
576         uart->port.irq = res2->start;
577         uart->port.dev = &pdev->dev;
578         uart->port.iotype = UPIO_MEM;
579         uart->port.flags = UPF_BOOT_AUTOCONF;
580         uart->port.line = dev_id;
581         uart->port.ops = &arc_serial_pops;
582 
583         uart->port.fifosize = ARC_UART_TX_FIFO_SIZE;
584 
585         /*
586          * uart_insert_char( ) uses it in decideding whether to ignore a
587          * char or not. Explicitly setting it here, removes the subtelty
588          */
589         uart->port.ignore_status_mask = 0;
590 
591         return 0;
592 }
593 
594 #ifdef CONFIG_SERIAL_ARC_CONSOLE
595 
596 static int arc_serial_console_setup(struct console *co, char *options)
597 {
598         struct uart_port *port;
599         int baud = 115200;
600         int bits = 8;
601         int parity = 'n';
602         int flow = 'n';
603 
604         if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)
605                 return -ENODEV;
606 
607         /*
608          * The uart port backing the console (e.g. ttyARC1) might not have been
609          * init yet. If so, defer the console setup to after the port.
610          */
611         port = &arc_uart_ports[co->index].port;
612         if (!port->membase)
613                 return -ENODEV;
614 
615         if (options)
616                 uart_parse_options(options, &baud, &parity, &bits, &flow);
617 
618         /*
619          * Serial core will call port->ops->set_termios( )
620          * which will set the baud reg
621          */
622         return uart_set_options(port, co, baud, parity, bits, flow);
623 }
624 
625 static void arc_serial_console_putchar(struct uart_port *port, int ch)
626 {
627         arc_serial_poll_putchar(port, (unsigned char)ch);
628 }
629 
630 /*
631  * Interrupts are disabled on entering
632  */
633 static void arc_serial_console_write(struct console *co, const char *s,
634                                      unsigned int count)
635 {
636         struct uart_port *port = &arc_uart_ports[co->index].port;
637         unsigned long flags;
638 
639         spin_lock_irqsave(&port->lock, flags);
640         uart_console_write(port, s, count, arc_serial_console_putchar);
641         spin_unlock_irqrestore(&port->lock, flags);
642 }
643 
644 static struct console arc_console = {
645         .name   = ARC_SERIAL_DEV_NAME,
646         .write  = arc_serial_console_write,
647         .device = uart_console_device,
648         .setup  = arc_serial_console_setup,
649         .flags  = CON_PRINTBUFFER,
650         .index  = -1,
651         .data   = &arc_uart_driver
652 };
653 
654 static __init void early_serial_write(struct console *con, const char *s,
655                                         unsigned int n)
656 {
657         struct uart_port *port = &arc_uart_ports[con->index].port;
658         unsigned int i;
659 
660         for (i = 0; i < n; i++, s++) {
661                 if (*s == '\n')
662                         arc_serial_poll_putchar(port, '\r');
663                 arc_serial_poll_putchar(port, *s);
664         }
665 }
666 
667 static struct console arc_early_serial_console __initdata = {
668         .name = "early_ARCuart",
669         .write = early_serial_write,
670         .flags = CON_PRINTBUFFER | CON_BOOT,
671         .index = -1
672 };
673 
674 static int __init arc_serial_probe_earlyprintk(struct platform_device *pdev)
675 {
676         int dev_id = pdev->id < 0 ? 0 : pdev->id;
677         int rc;
678 
679         arc_early_serial_console.index = dev_id;
680 
681         rc = arc_uart_init_one(pdev, dev_id);
682         if (rc)
683                 panic("early console init failed\n");
684 
685         arc_serial_console_setup(&arc_early_serial_console, NULL);
686 
687         register_console(&arc_early_serial_console);
688         return 0;
689 }
690 #endif  /* CONFIG_SERIAL_ARC_CONSOLE */
691 
692 static int arc_serial_probe(struct platform_device *pdev)
693 {
694         int rc, dev_id;
695         struct device_node *np = pdev->dev.of_node;
696 
697         /* no device tree device */
698         if (!np)
699                 return -ENODEV;
700 
701         dev_id = of_alias_get_id(np, "serial");
702         if (dev_id < 0)
703                 dev_id = 0;
704 
705         rc = arc_uart_init_one(pdev, dev_id);
706         if (rc)
707                 return rc;
708 
709         rc = uart_add_one_port(&arc_uart_driver, &arc_uart_ports[dev_id].port);
710         return rc;
711 }
712 
713 static int arc_serial_remove(struct platform_device *pdev)
714 {
715         /* This will never be called */
716         return 0;
717 }
718 
719 static const struct of_device_id arc_uart_dt_ids[] = {
720         { .compatible = "snps,arc-uart" },
721         { /* Sentinel */ }
722 };
723 MODULE_DEVICE_TABLE(of, arc_uart_dt_ids);
724 
725 static struct platform_driver arc_platform_driver = {
726         .probe = arc_serial_probe,
727         .remove = arc_serial_remove,
728         .driver = {
729                 .name = DRIVER_NAME,
730                 .owner = THIS_MODULE,
731                 .of_match_table  = arc_uart_dt_ids,
732          },
733 };
734 
735 #ifdef CONFIG_SERIAL_ARC_CONSOLE
736 
737 static struct platform_driver early_arc_platform_driver __initdata = {
738         .probe = arc_serial_probe_earlyprintk,
739         .remove = arc_serial_remove,
740         .driver = {
741                 .name = DRIVER_NAME,
742                 .owner = THIS_MODULE,
743          },
744 };
745 /*
746  * Register an early platform driver of "earlyprintk" class.
747  * ARCH platform code installs the driver and probes the early devices
748  * The installation could rely on user specifying earlyprintk=xyx in cmd line
749  * or it could be done independently, for all "earlyprintk" class drivers.
750  * [see arch/arc/plat-arcfpga/platform.c]
751  */
752 early_platform_init("earlyprintk", &early_arc_platform_driver);
753 
754 #endif  /* CONFIG_SERIAL_ARC_CONSOLE */
755 
756 static int __init arc_serial_init(void)
757 {
758         int ret;
759 
760         ret = uart_register_driver(&arc_uart_driver);
761         if (ret)
762                 return ret;
763 
764         ret = platform_driver_register(&arc_platform_driver);
765         if (ret)
766                 uart_unregister_driver(&arc_uart_driver);
767 
768         return ret;
769 }
770 
771 static void __exit arc_serial_exit(void)
772 {
773         platform_driver_unregister(&arc_platform_driver);
774         uart_unregister_driver(&arc_uart_driver);
775 }
776 
777 module_init(arc_serial_init);
778 module_exit(arc_serial_exit);
779 
780 MODULE_LICENSE("GPL");
781 MODULE_ALIAS("platform:" DRIVER_NAME);
782 MODULE_AUTHOR("Vineet Gupta");
783 MODULE_DESCRIPTION("ARC(Synopsys) On-Chip(fpga) serial driver");
784 

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