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 #include <xen/page.h>
29 #include <xen/events.h>
30 #include <xen/interface/io/console.h>
31 #include <xen/hvc-console.h>
32
33 #include "hvc_console.h"
34
35 #define HVC_COOKIE 0x58656e /* "Xen" in hex */
36
37 static struct hvc_struct *hvc;
38 static int xencons_irq;
39
40 /* ------------------------------------------------------------------ */
41
42 static inline struct xencons_interface *xencons_interface(void)
43 {
44 return mfn_to_virt(xen_start_info->console.domU.mfn);
45 }
46
47 static inline void notify_daemon(void)
48 {
49 /* Use evtchn: this is called early, before irq is set up. */
50 notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
51 }
52
53 static int write_console(uint32_t vtermno, const char *data, int len)
54 {
55 struct xencons_interface *intf = xencons_interface();
56 XENCONS_RING_IDX cons, prod;
57 int sent = 0;
58
59 cons = intf->out_cons;
60 prod = intf->out_prod;
61 mb(); /* update queue values before going on */
62 BUG_ON((prod - cons) > sizeof(intf->out));
63
64 while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
65 intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
66
67 wmb(); /* write ring before updating pointer */
68 intf->out_prod = prod;
69
70 notify_daemon();
71 return sent;
72 }
73
74 static int read_console(uint32_t vtermno, char *buf, int len)
75 {
76 struct xencons_interface *intf = xencons_interface();
77 XENCONS_RING_IDX cons, prod;
78 int recv = 0;
79
80 cons = intf->in_cons;
81 prod = intf->in_prod;
82 mb(); /* get pointers before reading ring */
83 BUG_ON((prod - cons) > sizeof(intf->in));
84
85 while (cons != prod && recv < len)
86 buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
87
88 mb(); /* read ring before consuming */
89 intf->in_cons = cons;
90
91 notify_daemon();
92 return recv;
93 }
94
95 static struct hv_ops hvc_ops = {
96 .get_chars = read_console,
97 .put_chars = write_console,
98 };
99
100 static int __init xen_init(void)
101 {
102 struct hvc_struct *hp;
103
104 if (!is_running_on_xen())
105 return 0;
106
107 xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
108 if (xencons_irq < 0)
109 xencons_irq = 0 /* NO_IRQ */;
110 hp = hvc_alloc(HVC_COOKIE, xencons_irq, &hvc_ops, 256);
111 if (IS_ERR(hp))
112 return PTR_ERR(hp);
113
114 hvc = hp;
115 return 0;
116 }
117
118 static void __exit xen_fini(void)
119 {
120 if (hvc)
121 hvc_remove(hvc);
122 }
123
124 static int xen_cons_init(void)
125 {
126 if (!is_running_on_xen())
127 return 0;
128
129 hvc_instantiate(HVC_COOKIE, 0, &hvc_ops);
130 return 0;
131 }
132
133 module_init(xen_init);
134 module_exit(xen_fini);
135 console_initcall(xen_cons_init);
136
137 static void xenboot_write_console(struct console *console, const char *string,
138 unsigned len)
139 {
140 unsigned int linelen, off = 0;
141 const char *pos;
142
143 while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
144 linelen = pos-string+off;
145 if (off + linelen > len)
146 break;
147 write_console(0, string+off, linelen);
148 write_console(0, "\r\n", 2);
149 off += linelen + 1;
150 }
151 if (off < len)
152 write_console(0, string+off, len-off);
153 }
154
155 struct console xenboot_console = {
156 .name = "xenboot",
157 .write = xenboot_write_console,
158 .flags = CON_PRINTBUFFER | CON_BOOT,
159 };
160
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