hvc_xen.c revision dced35aeb0367dda2636ee9ee914bda14510dcc9 
1/*
2 * xen console driver interface to hvc_console.c
3 *
4 * (c) 2007 Gerd Hoffmann <kraxel@suse.de>
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 as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
19 */
20
21#include <linux/console.h>
22#include <linux/delay.h>
23#include <linux/err.h>
24#include <linux/init.h>
25#include <linux/types.h>
26
27#include <asm/xen/hypervisor.h>
28
29#include <xen/xen.h>
30#include <xen/page.h>
31#include <xen/events.h>
32#include <xen/interface/io/console.h>
33#include <xen/hvc-console.h>
34
35#include "hvc_console.h"
36
37#define HVC_COOKIE   0x58656e /* "Xen" in hex */
38
39static struct hvc_struct *hvc;
40static int xencons_irq;
41
42/* ------------------------------------------------------------------ */
43
44static unsigned long console_pfn = ~0ul;
45
46static inline struct xencons_interface *xencons_interface(void)
47{
48	if (console_pfn == ~0ul)
49		return mfn_to_virt(xen_start_info->console.domU.mfn);
50	else
51		return __va(console_pfn << PAGE_SHIFT);
52}
53
54static inline void notify_daemon(void)
55{
56	/* Use evtchn: this is called early, before irq is set up. */
57	notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
58}
59
60static int __write_console(const char *data, int len)
61{
62	struct xencons_interface *intf = xencons_interface();
63	XENCONS_RING_IDX cons, prod;
64	int sent = 0;
65
66	cons = intf->out_cons;
67	prod = intf->out_prod;
68	mb();			/* update queue values before going on */
69	BUG_ON((prod - cons) > sizeof(intf->out));
70
71	while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
72		intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
73
74	wmb();			/* write ring before updating pointer */
75	intf->out_prod = prod;
76
77	if (sent)
78		notify_daemon();
79	return sent;
80}
81
82static int domU_write_console(uint32_t vtermno, const char *data, int len)
83{
84	int ret = len;
85
86	/*
87	 * Make sure the whole buffer is emitted, polling if
88	 * necessary.  We don't ever want to rely on the hvc daemon
89	 * because the most interesting console output is when the
90	 * kernel is crippled.
91	 */
92	while (len) {
93		int sent = __write_console(data, len);
94
95		data += sent;
96		len -= sent;
97
98		if (unlikely(len))
99			HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
100	}
101
102	return ret;
103}
104
105static int domU_read_console(uint32_t vtermno, char *buf, int len)
106{
107	struct xencons_interface *intf = xencons_interface();
108	XENCONS_RING_IDX cons, prod;
109	int recv = 0;
110
111	cons = intf->in_cons;
112	prod = intf->in_prod;
113	mb();			/* get pointers before reading ring */
114	BUG_ON((prod - cons) > sizeof(intf->in));
115
116	while (cons != prod && recv < len)
117		buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
118
119	mb();			/* read ring before consuming */
120	intf->in_cons = cons;
121
122	notify_daemon();
123	return recv;
124}
125
126static struct hv_ops domU_hvc_ops = {
127	.get_chars = domU_read_console,
128	.put_chars = domU_write_console,
129	.notifier_add = notifier_add_irq,
130	.notifier_del = notifier_del_irq,
131	.notifier_hangup = notifier_hangup_irq,
132};
133
134static int dom0_read_console(uint32_t vtermno, char *buf, int len)
135{
136	return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
137}
138
139/*
140 * Either for a dom0 to write to the system console, or a domU with a
141 * debug version of Xen
142 */
143static int dom0_write_console(uint32_t vtermno, const char *str, int len)
144{
145	int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
146	if (rc < 0)
147		return 0;
148
149	return len;
150}
151
152static struct hv_ops dom0_hvc_ops = {
153	.get_chars = dom0_read_console,
154	.put_chars = dom0_write_console,
155	.notifier_add = notifier_add_irq,
156	.notifier_del = notifier_del_irq,
157	.notifier_hangup = notifier_hangup_irq,
158};
159
160static int __init xen_hvc_init(void)
161{
162	struct hvc_struct *hp;
163	struct hv_ops *ops;
164
165	if (!xen_pv_domain())
166		return -ENODEV;
167
168	if (xen_initial_domain()) {
169		ops = &dom0_hvc_ops;
170		xencons_irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
171	} else {
172		if (!xen_start_info->console.domU.evtchn)
173			return -ENODEV;
174
175		ops = &domU_hvc_ops;
176		xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
177	}
178	if (xencons_irq < 0)
179		xencons_irq = 0; /* NO_IRQ */
180	else
181		irq_set_noprobe(xencons_irq);
182
183	hp = hvc_alloc(HVC_COOKIE, xencons_irq, ops, 256);
184	if (IS_ERR(hp))
185		return PTR_ERR(hp);
186
187	hvc = hp;
188
189	console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
190
191	return 0;
192}
193
194void xen_console_resume(void)
195{
196	if (xencons_irq)
197		rebind_evtchn_irq(xen_start_info->console.domU.evtchn, xencons_irq);
198}
199
200static void __exit xen_hvc_fini(void)
201{
202	if (hvc)
203		hvc_remove(hvc);
204}
205
206static int xen_cons_init(void)
207{
208	struct hv_ops *ops;
209
210	if (!xen_pv_domain())
211		return 0;
212
213	if (xen_initial_domain())
214		ops = &dom0_hvc_ops;
215	else
216		ops = &domU_hvc_ops;
217
218	hvc_instantiate(HVC_COOKIE, 0, ops);
219	return 0;
220}
221
222module_init(xen_hvc_init);
223module_exit(xen_hvc_fini);
224console_initcall(xen_cons_init);
225
226#ifdef CONFIG_EARLY_PRINTK
227static void xenboot_write_console(struct console *console, const char *string,
228				  unsigned len)
229{
230	unsigned int linelen, off = 0;
231	const char *pos;
232
233	dom0_write_console(0, string, len);
234
235	if (xen_initial_domain())
236		return;
237
238	domU_write_console(0, "(early) ", 8);
239	while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
240		linelen = pos-string+off;
241		if (off + linelen > len)
242			break;
243		domU_write_console(0, string+off, linelen);
244		domU_write_console(0, "\r\n", 2);
245		off += linelen + 1;
246	}
247	if (off < len)
248		domU_write_console(0, string+off, len-off);
249}
250
251struct console xenboot_console = {
252	.name		= "xenboot",
253	.write		= xenboot_write_console,
254	.flags		= CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
255};
256#endif	/* CONFIG_EARLY_PRINTK */
257
258void xen_raw_console_write(const char *str)
259{
260	dom0_write_console(0, str, strlen(str));
261}
262
263void xen_raw_printk(const char *fmt, ...)
264{
265	static char buf[512];
266	va_list ap;
267
268	va_start(ap, fmt);
269	vsnprintf(buf, sizeof(buf), fmt, ap);
270	va_end(ap);
271
272	xen_raw_console_write(buf);
273}
274