1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/kernel.h>
3 #include <linux/serial.h>
4 #include <linux/serial_8250.h>
5 #include <linux/serial_core.h>
6 #include <linux/console.h>
7 #include <linux/pci.h>
8 #include <linux/of.h>
9 #include <linux/of_address.h>
10 #include <linux/of_irq.h>
11 #include <linux/serial_reg.h>
12 #include <asm/io.h>
13 #include <asm/mmu.h>
14 #include <asm/serial.h>
15 #include <asm/udbg.h>
16 #include <asm/pci-bridge.h>
17 #include <asm/ppc-pci.h>
18 #include <asm/early_ioremap.h>
19 
20 #undef DEBUG
21 
22 #ifdef DEBUG
23 #define DBG(fmt...) do { printk(fmt); } while(0)
24 #else
25 #define DBG(fmt...) do { } while(0)
26 #endif
27 
28 #define MAX_LEGACY_SERIAL_PORTS	8
29 
30 static struct plat_serial8250_port
31 legacy_serial_ports[MAX_LEGACY_SERIAL_PORTS+1];
32 static struct legacy_serial_info {
33 	struct device_node		*np;
34 	unsigned int			speed;
35 	unsigned int			clock;
36 	int				irq_check_parent;
37 	phys_addr_t			taddr;
38 	void __iomem			*early_addr;
39 } legacy_serial_infos[MAX_LEGACY_SERIAL_PORTS];
40 
41 static const struct of_device_id legacy_serial_parents[] __initconst = {
42 	{.type = "soc",},
43 	{.type = "tsi-bridge",},
44 	{.type = "opb", },
45 	{.compatible = "ibm,opb",},
46 	{.compatible = "simple-bus",},
47 	{.compatible = "wrs,epld-localbus",},
48 	{},
49 };
50 
51 static unsigned int legacy_serial_count;
52 static int legacy_serial_console = -1;
53 
54 static const upf_t legacy_port_flags = UPF_BOOT_AUTOCONF | UPF_SKIP_TEST |
55 	UPF_SHARE_IRQ | UPF_FIXED_PORT;
56 
tsi_serial_in(struct uart_port * p,int offset)57 static unsigned int tsi_serial_in(struct uart_port *p, int offset)
58 {
59 	unsigned int tmp;
60 	offset = offset << p->regshift;
61 	if (offset == UART_IIR) {
62 		tmp = readl(p->membase + (UART_IIR & ~3));
63 		return (tmp >> 16) & 0xff; /* UART_IIR % 4 == 2 */
64 	} else
65 		return readb(p->membase + offset);
66 }
67 
tsi_serial_out(struct uart_port * p,int offset,int value)68 static void tsi_serial_out(struct uart_port *p, int offset, int value)
69 {
70 	offset = offset << p->regshift;
71 	if (!((offset == UART_IER) && (value & UART_IER_UUE)))
72 		writeb(value, p->membase + offset);
73 }
74 
add_legacy_port(struct device_node * np,int want_index,int iotype,phys_addr_t base,phys_addr_t taddr,unsigned long irq,upf_t flags,int irq_check_parent)75 static int __init add_legacy_port(struct device_node *np, int want_index,
76 				  int iotype, phys_addr_t base,
77 				  phys_addr_t taddr, unsigned long irq,
78 				  upf_t flags, int irq_check_parent)
79 {
80 	const __be32 *clk, *spd, *rs;
81 	u32 clock = BASE_BAUD * 16;
82 	u32 shift = 0;
83 	int index;
84 
85 	/* get clock freq. if present */
86 	clk = of_get_property(np, "clock-frequency", NULL);
87 	if (clk && *clk)
88 		clock = be32_to_cpup(clk);
89 
90 	/* get default speed if present */
91 	spd = of_get_property(np, "current-speed", NULL);
92 
93 	/* get register shift if present */
94 	rs = of_get_property(np, "reg-shift", NULL);
95 	if (rs && *rs)
96 		shift = be32_to_cpup(rs);
97 
98 	/* If we have a location index, then try to use it */
99 	if (want_index >= 0 && want_index < MAX_LEGACY_SERIAL_PORTS)
100 		index = want_index;
101 	else
102 		index = legacy_serial_count;
103 
104 	/* if our index is still out of range, that mean that
105 	 * array is full, we could scan for a free slot but that
106 	 * make little sense to bother, just skip the port
107 	 */
108 	if (index >= MAX_LEGACY_SERIAL_PORTS)
109 		return -1;
110 	if (index >= legacy_serial_count)
111 		legacy_serial_count = index + 1;
112 
113 	/* Check if there is a port who already claimed our slot */
114 	if (legacy_serial_infos[index].np != NULL) {
115 		/* if we still have some room, move it, else override */
116 		if (legacy_serial_count < MAX_LEGACY_SERIAL_PORTS) {
117 			printk(KERN_DEBUG "Moved legacy port %d -> %d\n",
118 			       index, legacy_serial_count);
119 			legacy_serial_ports[legacy_serial_count] =
120 				legacy_serial_ports[index];
121 			legacy_serial_infos[legacy_serial_count] =
122 				legacy_serial_infos[index];
123 			legacy_serial_count++;
124 		} else {
125 			printk(KERN_DEBUG "Replacing legacy port %d\n", index);
126 		}
127 	}
128 
129 	/* Now fill the entry */
130 	memset(&legacy_serial_ports[index], 0,
131 	       sizeof(struct plat_serial8250_port));
132 	if (iotype == UPIO_PORT)
133 		legacy_serial_ports[index].iobase = base;
134 	else
135 		legacy_serial_ports[index].mapbase = base;
136 
137 	legacy_serial_ports[index].iotype = iotype;
138 	legacy_serial_ports[index].uartclk = clock;
139 	legacy_serial_ports[index].irq = irq;
140 	legacy_serial_ports[index].flags = flags;
141 	legacy_serial_ports[index].regshift = shift;
142 	legacy_serial_infos[index].taddr = taddr;
143 	legacy_serial_infos[index].np = of_node_get(np);
144 	legacy_serial_infos[index].clock = clock;
145 	legacy_serial_infos[index].speed = spd ? be32_to_cpup(spd) : 0;
146 	legacy_serial_infos[index].irq_check_parent = irq_check_parent;
147 
148 	if (iotype == UPIO_TSI) {
149 		legacy_serial_ports[index].serial_in = tsi_serial_in;
150 		legacy_serial_ports[index].serial_out = tsi_serial_out;
151 	}
152 
153 	printk(KERN_DEBUG "Found legacy serial port %d for %pOF\n",
154 	       index, np);
155 	printk(KERN_DEBUG "  %s=%llx, taddr=%llx, irq=%lx, clk=%d, speed=%d\n",
156 	       (iotype == UPIO_PORT) ? "port" : "mem",
157 	       (unsigned long long)base, (unsigned long long)taddr, irq,
158 	       legacy_serial_ports[index].uartclk,
159 	       legacy_serial_infos[index].speed);
160 
161 	return index;
162 }
163 
add_legacy_soc_port(struct device_node * np,struct device_node * soc_dev)164 static int __init add_legacy_soc_port(struct device_node *np,
165 				      struct device_node *soc_dev)
166 {
167 	u64 addr;
168 	const __be32 *addrp;
169 	struct device_node *tsi = of_get_parent(np);
170 
171 	/* We only support ports that have a clock frequency properly
172 	 * encoded in the device-tree.
173 	 */
174 	if (!of_property_present(np, "clock-frequency"))
175 		return -1;
176 
177 	/* if reg-offset don't try to use it */
178 	if (of_property_present(np, "reg-offset"))
179 		return -1;
180 
181 	/* if rtas uses this device, don't try to use it as well */
182 	if (of_property_read_bool(np, "used-by-rtas"))
183 		return -1;
184 
185 	/* Get the address */
186 	addrp = of_get_address(soc_dev, 0, NULL, NULL);
187 	if (addrp == NULL)
188 		return -1;
189 
190 	addr = of_translate_address(soc_dev, addrp);
191 	if (addr == OF_BAD_ADDR)
192 		return -1;
193 
194 	/* Add port, irq will be dealt with later. We passed a translated
195 	 * IO port value. It will be fixed up later along with the irq
196 	 */
197 	if (of_node_is_type(tsi, "tsi-bridge"))
198 		return add_legacy_port(np, -1, UPIO_TSI, addr, addr,
199 				       0, legacy_port_flags, 0);
200 	else
201 		return add_legacy_port(np, -1, UPIO_MEM, addr, addr,
202 				       0, legacy_port_flags, 0);
203 }
204 
add_legacy_isa_port(struct device_node * np,struct device_node * isa_brg)205 static int __init add_legacy_isa_port(struct device_node *np,
206 				      struct device_node *isa_brg)
207 {
208 	const __be32 *reg;
209 	const char *typep;
210 	int index = -1;
211 	u64 taddr;
212 
213 	DBG(" -> add_legacy_isa_port(%pOF)\n", np);
214 
215 	/* Get the ISA port number */
216 	reg = of_get_property(np, "reg", NULL);
217 	if (reg == NULL)
218 		return -1;
219 
220 	/* Verify it's an IO port, we don't support anything else */
221 	if (!(be32_to_cpu(reg[0]) & 0x00000001))
222 		return -1;
223 
224 	/* Now look for an "ibm,aix-loc" property that gives us ordering
225 	 * if any...
226 	 */
227 	typep = of_get_property(np, "ibm,aix-loc", NULL);
228 
229 	/* If we have a location index, then use it */
230 	if (typep && *typep == 'S')
231 		index = simple_strtol(typep+1, NULL, 0) - 1;
232 
233 	/* Translate ISA address. If it fails, we still register the port
234 	 * with no translated address so that it can be picked up as an IO
235 	 * port later by the serial driver
236 	 *
237 	 * Note: Don't even try on P8 lpc, we know it's not directly mapped
238 	 */
239 	if (!of_device_is_compatible(isa_brg, "ibm,power8-lpc") ||
240 	    of_property_present(isa_brg, "ranges")) {
241 		taddr = of_translate_address(np, reg);
242 		if (taddr == OF_BAD_ADDR)
243 			taddr = 0;
244 	} else
245 		taddr = 0;
246 
247 	/* Add port, irq will be dealt with later */
248 	return add_legacy_port(np, index, UPIO_PORT, be32_to_cpu(reg[1]),
249 			       taddr, 0, legacy_port_flags, 0);
250 
251 }
252 
253 #ifdef CONFIG_PCI
add_legacy_pci_port(struct device_node * np,struct device_node * pci_dev)254 static int __init add_legacy_pci_port(struct device_node *np,
255 				      struct device_node *pci_dev)
256 {
257 	u64 addr, base;
258 	const __be32 *addrp;
259 	unsigned int flags;
260 	int iotype, index = -1, lindex = 0;
261 
262 	DBG(" -> add_legacy_pci_port(%pOF)\n", np);
263 
264 	/* We only support ports that have a clock frequency properly
265 	 * encoded in the device-tree (that is have an fcode). Anything
266 	 * else can't be used that early and will be normally probed by
267 	 * the generic 8250_pci driver later on. The reason is that 8250
268 	 * compatible UARTs on PCI need all sort of quirks (port offsets
269 	 * etc...) that this code doesn't know about
270 	 */
271 	if (!of_property_present(np, "clock-frequency"))
272 		return -1;
273 
274 	/* Get the PCI address. Assume BAR 0 */
275 	addrp = of_get_pci_address(pci_dev, 0, NULL, &flags);
276 	if (addrp == NULL)
277 		return -1;
278 
279 	/* We only support BAR 0 for now */
280 	iotype = (flags & IORESOURCE_MEM) ? UPIO_MEM : UPIO_PORT;
281 	addr = of_translate_address(pci_dev, addrp);
282 	if (addr == OF_BAD_ADDR)
283 		return -1;
284 
285 	/* Set the IO base to the same as the translated address for MMIO,
286 	 * or to the domain local IO base for PIO (it will be fixed up later)
287 	 */
288 	if (iotype == UPIO_MEM)
289 		base = addr;
290 	else
291 		base = of_read_number(&addrp[2], 1);
292 
293 	/* Try to guess an index... If we have subdevices of the pci dev,
294 	 * we get to their "reg" property
295 	 */
296 	if (np != pci_dev) {
297 		const __be32 *reg = of_get_property(np, "reg", NULL);
298 		if (reg && (be32_to_cpup(reg) < 4))
299 			index = lindex = be32_to_cpup(reg);
300 	}
301 
302 	/* Local index means it's the Nth port in the PCI chip. Unfortunately
303 	 * the offset to add here is device specific. We know about those
304 	 * EXAR ports and we default to the most common case. If your UART
305 	 * doesn't work for these settings, you'll have to add your own special
306 	 * cases here
307 	 */
308 	if (of_device_is_compatible(pci_dev, "pci13a8,152") ||
309 	    of_device_is_compatible(pci_dev, "pci13a8,154") ||
310 	    of_device_is_compatible(pci_dev, "pci13a8,158")) {
311 		addr += 0x200 * lindex;
312 		base += 0x200 * lindex;
313 	} else {
314 		addr += 8 * lindex;
315 		base += 8 * lindex;
316 	}
317 
318 	/* Add port, irq will be dealt with later. We passed a translated
319 	 * IO port value. It will be fixed up later along with the irq
320 	 */
321 	return add_legacy_port(np, index, iotype, base, addr, 0,
322 			       legacy_port_flags, np != pci_dev);
323 }
324 #endif
325 
setup_legacy_serial_console(int console)326 static void __init setup_legacy_serial_console(int console)
327 {
328 	struct legacy_serial_info *info = &legacy_serial_infos[console];
329 	struct plat_serial8250_port *port = &legacy_serial_ports[console];
330 	unsigned int stride;
331 
332 	stride = 1 << port->regshift;
333 
334 	/* Check if a translated MMIO address has been found */
335 	if (info->taddr) {
336 		info->early_addr = early_ioremap(info->taddr, 0x1000);
337 		if (info->early_addr == NULL)
338 			return;
339 		udbg_uart_init_mmio(info->early_addr, stride);
340 	} else {
341 		/* Check if it's PIO and we support untranslated PIO */
342 		if (port->iotype == UPIO_PORT && isa_io_special)
343 			udbg_uart_init_pio(port->iobase, stride);
344 		else
345 			return;
346 	}
347 
348 	/* Try to query the current speed */
349 	if (info->speed == 0)
350 		info->speed = udbg_probe_uart_speed(info->clock);
351 
352 	/* Set it up */
353 	DBG("default console speed = %d\n", info->speed);
354 	udbg_uart_setup(info->speed, info->clock);
355 }
356 
ioremap_legacy_serial_console(void)357 static int __init ioremap_legacy_serial_console(void)
358 {
359 	struct plat_serial8250_port *port;
360 	struct legacy_serial_info *info;
361 	void __iomem *vaddr;
362 
363 	if (legacy_serial_console < 0)
364 		return 0;
365 
366 	info = &legacy_serial_infos[legacy_serial_console];
367 	port = &legacy_serial_ports[legacy_serial_console];
368 
369 	if (!info->early_addr)
370 		return 0;
371 
372 	vaddr = ioremap(info->taddr, 0x1000);
373 	if (WARN_ON(!vaddr))
374 		return -ENOMEM;
375 
376 	udbg_uart_init_mmio(vaddr, 1 << port->regshift);
377 	early_iounmap(info->early_addr, 0x1000);
378 	info->early_addr = NULL;
379 
380 	return 0;
381 }
382 early_initcall(ioremap_legacy_serial_console);
383 
384 /*
385  * This is called very early, as part of setup_system() or eventually
386  * setup_arch(), basically before anything else in this file. This function
387  * will try to build a list of all the available 8250-compatible serial ports
388  * in the machine using the Open Firmware device-tree. It currently only deals
389  * with ISA and PCI busses but could be extended. It allows a very early boot
390  * console to be initialized, that list is also used later to provide 8250 with
391  * the machine non-PCI ports and to properly pick the default console port
392  */
find_legacy_serial_ports(void)393 void __init find_legacy_serial_ports(void)
394 {
395 	struct device_node *np, *stdout = NULL;
396 	const char *path;
397 	int index;
398 
399 	DBG(" -> find_legacy_serial_port()\n");
400 
401 	/* Now find out if one of these is out firmware console */
402 	path = of_get_property(of_chosen, "linux,stdout-path", NULL);
403 	if (path == NULL)
404 		path = of_get_property(of_chosen, "stdout-path", NULL);
405 	if (path != NULL) {
406 		stdout = of_find_node_by_path(path);
407 		if (stdout)
408 			DBG("stdout is %pOF\n", stdout);
409 	} else {
410 		DBG(" no linux,stdout-path !\n");
411 	}
412 
413 	/* Iterate over all the 16550 ports, looking for known parents */
414 	for_each_compatible_node(np, "serial", "ns16550") {
415 		struct device_node *parent = of_get_parent(np);
416 		if (!parent)
417 			continue;
418 		if (of_match_node(legacy_serial_parents, parent) != NULL) {
419 			if (of_device_is_available(np)) {
420 				index = add_legacy_soc_port(np, np);
421 				if (index >= 0 && np == stdout)
422 					legacy_serial_console = index;
423 			}
424 		}
425 		of_node_put(parent);
426 	}
427 
428 	/* Next, fill our array with ISA ports */
429 	for_each_node_by_type(np, "serial") {
430 		struct device_node *isa = of_get_parent(np);
431 		if (of_node_name_eq(isa, "isa") || of_node_name_eq(isa, "lpc")) {
432 			if (of_device_is_available(np)) {
433 				index = add_legacy_isa_port(np, isa);
434 				if (index >= 0 && np == stdout)
435 					legacy_serial_console = index;
436 			}
437 		}
438 		of_node_put(isa);
439 	}
440 
441 #ifdef CONFIG_PCI
442 	/* Next, try to locate PCI ports */
443 	for (np = NULL; (np = of_find_all_nodes(np));) {
444 		struct device_node *pci, *parent = of_get_parent(np);
445 		if (of_node_name_eq(parent, "isa")) {
446 			of_node_put(parent);
447 			continue;
448 		}
449 		if (!of_node_name_eq(np, "serial") &&
450 		    !of_node_is_type(np, "serial")) {
451 			of_node_put(parent);
452 			continue;
453 		}
454 		/* Check for known pciclass, and also check whether we have
455 		 * a device with child nodes for ports or not
456 		 */
457 		if (of_device_is_compatible(np, "pciclass,0700") ||
458 		    of_device_is_compatible(np, "pciclass,070002"))
459 			pci = np;
460 		else if (of_device_is_compatible(parent, "pciclass,0700") ||
461 			 of_device_is_compatible(parent, "pciclass,070002"))
462 			pci = parent;
463 		else {
464 			of_node_put(parent);
465 			continue;
466 		}
467 		index = add_legacy_pci_port(np, pci);
468 		if (index >= 0 && np == stdout)
469 			legacy_serial_console = index;
470 		of_node_put(parent);
471 	}
472 #endif
473 
474 	of_node_put(stdout);
475 
476 	DBG("legacy_serial_console = %d\n", legacy_serial_console);
477 	if (legacy_serial_console >= 0)
478 		setup_legacy_serial_console(legacy_serial_console);
479 	DBG(" <- find_legacy_serial_port()\n");
480 }
481 
482 static struct platform_device serial_device = {
483 	.name	= "serial8250",
484 	.id	= PLAT8250_DEV_PLATFORM,
485 	.dev	= {
486 		.platform_data = legacy_serial_ports,
487 	},
488 };
489 
fixup_port_irq(int index,struct device_node * np,struct plat_serial8250_port * port)490 static void __init fixup_port_irq(int index,
491 				  struct device_node *np,
492 				  struct plat_serial8250_port *port)
493 {
494 	unsigned int virq;
495 
496 	DBG("fixup_port_irq(%d)\n", index);
497 
498 	virq = irq_of_parse_and_map(np, 0);
499 	if (!virq && legacy_serial_infos[index].irq_check_parent) {
500 		np = of_get_parent(np);
501 		if (np == NULL)
502 			return;
503 		virq = irq_of_parse_and_map(np, 0);
504 		of_node_put(np);
505 	}
506 	if (!virq)
507 		return;
508 
509 	port->irq = virq;
510 
511 	if (IS_ENABLED(CONFIG_SERIAL_8250) &&
512 	    of_device_is_compatible(np, "fsl,ns16550")) {
513 		if (IS_REACHABLE(CONFIG_SERIAL_8250_FSL)) {
514 			port->handle_irq = fsl8250_handle_irq;
515 			port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE);
516 		} else {
517 			pr_warn_once("Not activating Freescale specific workaround for device %pOFP\n",
518 				     np);
519 		}
520 	}
521 }
522 
fixup_port_pio(int index,struct device_node * np,struct plat_serial8250_port * port)523 static void __init fixup_port_pio(int index,
524 				  struct device_node *np,
525 				  struct plat_serial8250_port *port)
526 {
527 #ifdef CONFIG_PCI
528 	struct pci_controller *hose;
529 
530 	DBG("fixup_port_pio(%d)\n", index);
531 
532 	hose = pci_find_hose_for_OF_device(np);
533 	if (hose) {
534 		unsigned long offset = (unsigned long)hose->io_base_virt -
535 #ifdef CONFIG_PPC64
536 			pci_io_base;
537 #else
538 			isa_io_base;
539 #endif
540 		DBG("port %d, IO %lx -> %lx\n",
541 		    index, port->iobase, port->iobase + offset);
542 		port->iobase += offset;
543 	}
544 #endif
545 }
546 
fixup_port_mmio(int index,struct device_node * np,struct plat_serial8250_port * port)547 static void __init fixup_port_mmio(int index,
548 				   struct device_node *np,
549 				   struct plat_serial8250_port *port)
550 {
551 	DBG("fixup_port_mmio(%d)\n", index);
552 
553 	port->membase = ioremap(port->mapbase, 0x100);
554 }
555 
556 /*
557  * This is called as an arch initcall, hopefully before the PCI bus is
558  * probed and/or the 8250 driver loaded since we need to register our
559  * platform devices before 8250 PCI ones are detected as some of them
560  * must properly "override" the platform ones.
561  *
562  * This function fixes up the interrupt value for platform ports as it
563  * couldn't be done earlier before interrupt maps have been parsed. It
564  * also "corrects" the IO address for PIO ports for the same reason,
565  * since earlier, the PHBs virtual IO space wasn't assigned yet. It then
566  * registers all those platform ports for use by the 8250 driver when it
567  * finally loads.
568  */
serial_dev_init(void)569 static int __init serial_dev_init(void)
570 {
571 	int i;
572 
573 	if (legacy_serial_count == 0)
574 		return -ENODEV;
575 
576 	/*
577 	 * Before we register the platform serial devices, we need
578 	 * to fixup their interrupts and their IO ports.
579 	 */
580 	DBG("Fixing serial ports interrupts and IO ports ...\n");
581 
582 	for (i = 0; i < legacy_serial_count; i++) {
583 		struct plat_serial8250_port *port = &legacy_serial_ports[i];
584 		struct device_node *np = legacy_serial_infos[i].np;
585 
586 		if (!port->irq)
587 			fixup_port_irq(i, np, port);
588 		if (port->iotype == UPIO_PORT)
589 			fixup_port_pio(i, np, port);
590 		if ((port->iotype == UPIO_MEM) || (port->iotype == UPIO_TSI))
591 			fixup_port_mmio(i, np, port);
592 	}
593 
594 	DBG("Registering platform serial ports\n");
595 
596 	return platform_device_register(&serial_device);
597 }
598 device_initcall(serial_dev_init);
599 
600 
601 #ifdef CONFIG_SERIAL_8250_CONSOLE
602 /*
603  * This is called very early, as part of console_init() (typically just after
604  * time_init()). This function is respondible for trying to find a good
605  * default console on serial ports. It tries to match the open firmware
606  * default output with one of the available serial console drivers that have
607  * been probed earlier by find_legacy_serial_ports()
608  */
check_legacy_serial_console(void)609 static int __init check_legacy_serial_console(void)
610 {
611 	struct device_node *prom_stdout = NULL;
612 	int i, speed = 0, offset = 0;
613 	const char *name;
614 	const __be32 *spd;
615 
616 	DBG(" -> check_legacy_serial_console()\n");
617 
618 	/* The user has requested a console so this is already set up. */
619 	if (strstr(boot_command_line, "console=")) {
620 		DBG(" console was specified !\n");
621 		return -EBUSY;
622 	}
623 
624 	if (!of_chosen) {
625 		DBG(" of_chosen is NULL !\n");
626 		return -ENODEV;
627 	}
628 
629 	if (legacy_serial_console < 0) {
630 		DBG(" legacy_serial_console not found !\n");
631 		return -ENODEV;
632 	}
633 	/* We are getting a weird phandle from OF ... */
634 	/* ... So use the full path instead */
635 	name = of_get_property(of_chosen, "linux,stdout-path", NULL);
636 	if (name == NULL)
637 		name = of_get_property(of_chosen, "stdout-path", NULL);
638 	if (name == NULL) {
639 		DBG(" no stdout-path !\n");
640 		return -ENODEV;
641 	}
642 	prom_stdout = of_find_node_by_path(name);
643 	if (!prom_stdout) {
644 		DBG(" can't find stdout package %s !\n", name);
645 		return -ENODEV;
646 	}
647 	DBG("stdout is %pOF\n", prom_stdout);
648 
649 	name = of_get_property(prom_stdout, "name", NULL);
650 	if (!name) {
651 		DBG(" stdout package has no name !\n");
652 		goto not_found;
653 	}
654 	spd = of_get_property(prom_stdout, "current-speed", NULL);
655 	if (spd)
656 		speed = be32_to_cpup(spd);
657 
658 	if (strcmp(name, "serial") != 0)
659 		goto not_found;
660 
661 	/* Look for it in probed array */
662 	for (i = 0; i < legacy_serial_count; i++) {
663 		if (prom_stdout != legacy_serial_infos[i].np)
664 			continue;
665 		offset = i;
666 		speed = legacy_serial_infos[i].speed;
667 		break;
668 	}
669 	if (i >= legacy_serial_count)
670 		goto not_found;
671 
672 	of_node_put(prom_stdout);
673 
674 	DBG("Found serial console at ttyS%d\n", offset);
675 
676 	if (speed) {
677 		static char __initdata opt[16];
678 		sprintf(opt, "%d", speed);
679 		return add_preferred_console("ttyS", offset, opt);
680 	} else
681 		return add_preferred_console("ttyS", offset, NULL);
682 
683  not_found:
684 	DBG("No preferred console found !\n");
685 	of_node_put(prom_stdout);
686 	return -ENODEV;
687 }
688 console_initcall(check_legacy_serial_console);
689 
690 #endif /* CONFIG_SERIAL_8250_CONSOLE */
691