1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright 2014 Broadcom Corporation
4 */
5
6 /*
7 * Minimal semihosting implementation for reading files into memory. If more
8 * features like writing files or console output are required they can be
9 * added later. This code has been tested on arm64/aarch64 fastmodel only.
10 * An untested placeholder exists for armv7 architectures, but since they
11 * are commonly available in silicon now, fastmodel usage makes less sense
12 * for them.
13 */
14 #include <common.h>
15 #include <command.h>
16
17 #define SYSOPEN 0x01
18 #define SYSCLOSE 0x02
19 #define SYSREAD 0x06
20 #define SYSFLEN 0x0C
21
22 #define MODE_READ 0x0
23 #define MODE_READBIN 0x1
24
25 /*
26 * Call the handler
27 */
smh_trap(unsigned int sysnum,void * addr)28 static noinline long smh_trap(unsigned int sysnum, void *addr)
29 {
30 register long result asm("r0");
31 #if defined(CONFIG_ARM64)
32 asm volatile ("hlt #0xf000" : "=r" (result) : "0"(sysnum), "r"(addr));
33 #elif defined(CONFIG_CPU_V7M)
34 asm volatile ("bkpt #0xAB" : "=r" (result) : "0"(sysnum), "r"(addr));
35 #else
36 /* Note - untested placeholder */
37 asm volatile ("svc #0x123456" : "=r" (result) : "0"(sysnum), "r"(addr));
38 #endif
39 return result;
40 }
41
42 /*
43 * Open a file on the host. Mode is "r" or "rb" currently. Returns a file
44 * descriptor or -1 on error.
45 */
smh_open(const char * fname,char * modestr)46 static long smh_open(const char *fname, char *modestr)
47 {
48 long fd;
49 unsigned long mode;
50 struct smh_open_s {
51 const char *fname;
52 unsigned long mode;
53 size_t len;
54 } open;
55
56 debug("%s: file \'%s\', mode \'%s\'\n", __func__, fname, modestr);
57
58 /* Check the file mode */
59 if (!(strcmp(modestr, "r"))) {
60 mode = MODE_READ;
61 } else if (!(strcmp(modestr, "rb"))) {
62 mode = MODE_READBIN;
63 } else {
64 printf("%s: ERROR mode \'%s\' not supported\n", __func__,
65 modestr);
66 return -1;
67 }
68
69 open.fname = fname;
70 open.len = strlen(fname);
71 open.mode = mode;
72
73 /* Open the file on the host */
74 fd = smh_trap(SYSOPEN, &open);
75 if (fd == -1)
76 printf("%s: ERROR fd %ld for file \'%s\'\n", __func__, fd,
77 fname);
78
79 return fd;
80 }
81
82 /*
83 * Read 'len' bytes of file into 'memp'. Returns 0 on success, else failure
84 */
smh_read(long fd,void * memp,size_t len)85 static long smh_read(long fd, void *memp, size_t len)
86 {
87 long ret;
88 struct smh_read_s {
89 long fd;
90 void *memp;
91 size_t len;
92 } read;
93
94 debug("%s: fd %ld, memp %p, len %zu\n", __func__, fd, memp, len);
95
96 read.fd = fd;
97 read.memp = memp;
98 read.len = len;
99
100 ret = smh_trap(SYSREAD, &read);
101 if (ret < 0) {
102 /*
103 * The ARM handler allows for returning partial lengths,
104 * but in practice this never happens so rather than create
105 * hard to maintain partial read loops and such, just fail
106 * with an error message.
107 */
108 printf("%s: ERROR ret %ld, fd %ld, len %zu memp %p\n",
109 __func__, ret, fd, len, memp);
110 return -1;
111 }
112
113 return 0;
114 }
115
116 /*
117 * Close the file using the file descriptor
118 */
smh_close(long fd)119 static long smh_close(long fd)
120 {
121 long ret;
122
123 debug("%s: fd %ld\n", __func__, fd);
124
125 ret = smh_trap(SYSCLOSE, &fd);
126 if (ret == -1)
127 printf("%s: ERROR fd %ld\n", __func__, fd);
128
129 return ret;
130 }
131
132 /*
133 * Get the file length from the file descriptor
134 */
smh_len_fd(long fd)135 static long smh_len_fd(long fd)
136 {
137 long ret;
138
139 debug("%s: fd %ld\n", __func__, fd);
140
141 ret = smh_trap(SYSFLEN, &fd);
142 if (ret == -1)
143 printf("%s: ERROR ret %ld, fd %ld\n", __func__, ret, fd);
144
145 return ret;
146 }
147
smh_load_file(const char * const name,ulong load_addr,ulong * end_addr)148 static int smh_load_file(const char * const name, ulong load_addr,
149 ulong *end_addr)
150 {
151 long fd;
152 long len;
153 long ret;
154
155 fd = smh_open(name, "rb");
156 if (fd == -1)
157 return -1;
158
159 len = smh_len_fd(fd);
160 if (len < 0) {
161 smh_close(fd);
162 return -1;
163 }
164
165 ret = smh_read(fd, (void *)load_addr, len);
166 smh_close(fd);
167
168 if (ret == 0) {
169 *end_addr = load_addr + len - 1;
170 printf("loaded file %s from %08lX to %08lX, %08lX bytes\n",
171 name,
172 load_addr,
173 *end_addr,
174 len);
175 } else {
176 printf("read failed\n");
177 return 0;
178 }
179
180 return 0;
181 }
182
do_smhload(cmd_tbl_t * cmdtp,int flag,int argc,char * const argv[])183 static int do_smhload(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
184 {
185 if (argc == 3 || argc == 4) {
186 ulong load_addr;
187 ulong end_addr = 0;
188 int ret;
189 char end_str[64];
190
191 load_addr = simple_strtoul(argv[2], NULL, 16);
192 if (!load_addr)
193 return -1;
194
195 ret = smh_load_file(argv[1], load_addr, &end_addr);
196 if (ret < 0)
197 return CMD_RET_FAILURE;
198
199 /* Optionally save returned end to the environment */
200 if (argc == 4) {
201 sprintf(end_str, "0x%08lx", end_addr);
202 env_set(argv[3], end_str);
203 }
204 } else {
205 return CMD_RET_USAGE;
206 }
207 return 0;
208 }
209
210 U_BOOT_CMD(smhload, 4, 0, do_smhload, "load a file using semihosting",
211 "<file> 0x<address> [end var]\n"
212 " - load a semihosted file to the address specified\n"
213 " if the optional [end var] is specified, the end\n"
214 " address of the file will be stored in this environment\n"
215 " variable.\n");
216