1 /*
2 * Console via Blackfin JTAG Communication
3 *
4 * Copyright 2008-2011 Analog Devices Inc.
5 *
6 * Enter bugs at http://blackfin.uclinux.org/
7 *
8 * Licensed under the GPL-2 or later.
9 */
10
11 #include <linux/console.h>
12 #include <linux/delay.h>
13 #include <linux/err.h>
14 #include <linux/init.h>
15 #include <linux/moduleparam.h>
16 #include <linux/types.h>
17
18 #include "hvc_console.h"
19
20 /* See the Debug/Emulation chapter in the HRM */
21 #define EMUDOF 0x00000001 /* EMUDAT_OUT full & valid */
22 #define EMUDIF 0x00000002 /* EMUDAT_IN full & valid */
23 #define EMUDOOVF 0x00000004 /* EMUDAT_OUT overflow */
24 #define EMUDIOVF 0x00000008 /* EMUDAT_IN overflow */
25
26 /* Helper functions to glue the register API to simple C operations */
bfin_write_emudat(uint32_t emudat)27 static inline uint32_t bfin_write_emudat(uint32_t emudat)
28 {
29 __asm__ __volatile__("emudat = %0;" : : "d"(emudat));
30 return emudat;
31 }
32
bfin_read_emudat(void)33 static inline uint32_t bfin_read_emudat(void)
34 {
35 uint32_t emudat;
36 __asm__ __volatile__("%0 = emudat;" : "=d"(emudat));
37 return emudat;
38 }
39
40 /* Send data to the host */
hvc_bfin_put_chars(uint32_t vt,const char * buf,int count)41 static int hvc_bfin_put_chars(uint32_t vt, const char *buf, int count)
42 {
43 static uint32_t outbound_len;
44 uint32_t emudat;
45 int ret;
46
47 if (bfin_read_DBGSTAT() & EMUDOF)
48 return 0;
49
50 if (!outbound_len) {
51 outbound_len = count;
52 bfin_write_emudat(outbound_len);
53 return 0;
54 }
55
56 ret = min(outbound_len, (uint32_t)4);
57 memcpy(&emudat, buf, ret);
58 bfin_write_emudat(emudat);
59 outbound_len -= ret;
60
61 return ret;
62 }
63
64 /* Receive data from the host */
hvc_bfin_get_chars(uint32_t vt,char * buf,int count)65 static int hvc_bfin_get_chars(uint32_t vt, char *buf, int count)
66 {
67 static uint32_t inbound_len;
68 uint32_t emudat;
69 int ret;
70
71 if (!(bfin_read_DBGSTAT() & EMUDIF))
72 return 0;
73 emudat = bfin_read_emudat();
74
75 if (!inbound_len) {
76 inbound_len = emudat;
77 return 0;
78 }
79
80 ret = min(inbound_len, (uint32_t)4);
81 memcpy(buf, &emudat, ret);
82 inbound_len -= ret;
83
84 return ret;
85 }
86
87 /* Glue the HVC layers to the Blackfin layers */
88 static const struct hv_ops hvc_bfin_get_put_ops = {
89 .get_chars = hvc_bfin_get_chars,
90 .put_chars = hvc_bfin_put_chars,
91 };
92
hvc_bfin_console_init(void)93 static int __init hvc_bfin_console_init(void)
94 {
95 hvc_instantiate(0, 0, &hvc_bfin_get_put_ops);
96 return 0;
97 }
98 console_initcall(hvc_bfin_console_init);
99
hvc_bfin_init(void)100 static int __init hvc_bfin_init(void)
101 {
102 hvc_alloc(0, 0, &hvc_bfin_get_put_ops, 128);
103 return 0;
104 }
105 device_initcall(hvc_bfin_init);
106