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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