i2ctransfer: new applet

i2ctransfer sends and receives user defined i2c messages

v2: apply Xabier's comments: add -a option, don't decrement argc,
    use bb_show_usage() and xzalloc()
v3: fix possible out of bound access to msgs[nmsgs]

Reviewed-by: Xabier Oneca -- xOneca <xoneca@gmail.com>
Signed-off-by: Nikolaus Voss <nikolaus.voss@loewensteinmedical.de>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 177 insertions, 1 deletions

diff --git a/miscutils/i2c_tools.c b/miscutils/i2c_tools.c
index 610fed5d6..455ff028d 100644
--- a/miscutils/i2c_tools.c
+++ b/miscutils/i2c_tools.c
@@ -36,17 +36,26 @@
 //config:       help
 //config:       Detect I2C chips.
 //config:
+//config:config I2CTRANSFER
+//config:       bool "i2ctransfer (4.0 kb)"
+//config:       default y
+//config:       select PLATFORM_LINUX
+//config:       help
+//config:       Send user-defined I2C messages in one transfer.
+//config:
 
 //applet:IF_I2CGET(APPLET(i2cget, BB_DIR_USR_SBIN, BB_SUID_DROP))
 //applet:IF_I2CSET(APPLET(i2cset, BB_DIR_USR_SBIN, BB_SUID_DROP))
 //applet:IF_I2CDUMP(APPLET(i2cdump, BB_DIR_USR_SBIN, BB_SUID_DROP))
 //applet:IF_I2CDETECT(APPLET(i2cdetect, BB_DIR_USR_SBIN, BB_SUID_DROP))
+//applet:IF_I2CTRANSFER(APPLET(i2ctransfer, BB_DIR_USR_SBIN, BB_SUID_DROP))
 /* not NOEXEC: if hw operation stalls, use less memory in "hung" process */
 
 //kbuild:lib-$(CONFIG_I2CGET) += i2c_tools.o
 //kbuild:lib-$(CONFIG_I2CSET) += i2c_tools.o
 //kbuild:lib-$(CONFIG_I2CDUMP) += i2c_tools.o
 //kbuild:lib-$(CONFIG_I2CDETECT) += i2c_tools.o
+//kbuild:lib-$(CONFIG_I2CTRANSFER) += i2c_tools.o
 
 /*
  * Unsupported stuff:
@@ -80,12 +89,19 @@
 #define I2C_FUNCS                       0x0705
 #define I2C_PEC                         0x0708
 #define I2C_SMBUS                       0x0720
+#define I2C_RDWR                        0x0707
+#define I2C_RDWR_IOCTL_MAX_MSGS         42
+#define I2C_RDWR_IOCTL_MAX_MSGS_STR     "42"
 struct i2c_smbus_ioctl_data {
         __u8 read_write;
         __u8 command;
         __u32 size;
         union i2c_smbus_data *data;
 };
+struct i2c_rdwr_ioctl_data {
+        struct i2c_msg *msgs;   /* pointers to i2c_msgs */
+        __u32 nmsgs;            /* number of i2c_msgs */
+};
 /* end linux/i2c-dev.h */
 
 /*
@@ -262,7 +278,7 @@ static int i2c_bus_lookup(const char *bus_str)
         return xstrtou_range(bus_str, 10, 0, 0xfffff);
 }
 
-#if ENABLE_I2CGET || ENABLE_I2CSET || ENABLE_I2CDUMP
+#if ENABLE_I2CGET || ENABLE_I2CSET || ENABLE_I2CDUMP || ENABLE_I2CTRANSFER
 static int i2c_parse_bus_addr(const char *addr_str)
 {
         /* Slave address must be in range 0x03 - 0x77. */
@@ -1373,3 +1389,163 @@ int i2cdetect_main(int argc UNUSED_PARAM, char **argv)
         return 0;
 }
 #endif /* ENABLE_I2CDETECT */
+
+#if ENABLE_I2CTRANSFER
+static void check_i2c_func(int fd)
+{
+        unsigned long funcs;
+
+        get_funcs_matrix(fd, &funcs);
+
+        if (!(funcs & I2C_FUNC_I2C))
+                bb_error_msg_and_die("adapter does not support I2C transfers");
+}
+
+//usage:#define i2ctransfer_trivial_usage
+//usage:       "[-fay] I2CBUS {rLENGTH[@ADDR] | wLENGTH[@ADDR] DATA...}..."
+//usage:#define i2ctransfer_full_usage "\n\n"
+//usage:       "Read/write I2C data in one transfer"
+//usage:     "\n"
+//usage:     "\n        -f      Force access"
+//usage:     "\n        -a      Force scanning of non-regular addresses"
+//usage:     "\n        -y      Disable interactive mode"
+int i2ctransfer_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int i2ctransfer_main(int argc UNUSED_PARAM, char **argv)
+{
+        enum {
+                opt_f = (1 << 0),
+                opt_y = (1 << 1),
+                opt_a = (1 << 2),
+        };
+        int bus_num, bus_addr;
+        int fd;
+        unsigned opts, first, last;
+        int nmsgs, nmsgs_sent, i;
+        struct i2c_msg msgs[I2C_RDWR_IOCTL_MAX_MSGS];
+        struct i2c_rdwr_ioctl_data rdwr;
+
+        memset(msgs, 0, sizeof(msgs));
+
+        opts = getopt32(argv, "^"
+                "fya"
+                "\0" "-2" /* minimum 2 args */
+        );
+        first = 0x03;
+        last = 0x77;
+        if (opts & opt_a) {
+                first = 0x00;
+                last = 0x7f;
+        }
+
+        argv += optind;
+        bus_num = i2c_bus_lookup(argv[0]);
+        fd = i2c_dev_open(bus_num);
+        check_i2c_func(fd);
+
+        bus_addr = -1;
+        nmsgs = 0;
+        while (*++argv) {
+                char *arg_ptr;
+                unsigned len;
+                uint16_t flags;
+                char *end;
+
+                if (nmsgs >= I2C_RDWR_IOCTL_MAX_MSGS)
+                        bb_error_msg_and_die("too many messages, max: "I2C_RDWR_IOCTL_MAX_MSGS_STR);
+
+                flags = 0;
+                arg_ptr = *argv;
+                switch (*arg_ptr++) {
+                case 'r': flags |= I2C_M_RD; break;
+                case 'w': break;
+                default:
+                        bb_show_usage();
+                }
+
+                end = strchr(arg_ptr, '@');
+                if (end) *end = '\0';
+                len = xstrtou_range(arg_ptr, 0, 0, 0xffff);
+                if (end) {
+                        bus_addr = xstrtou_range(end + 1, 0, first, last);
+//TODO: will this work correctly if -f is specified?
+                        if (!(opts & opt_f))
+                                i2c_set_slave_addr(fd, bus_addr, (opts & opt_f));
+                } else {
+                        /* Reuse last address if possible */
+                        if (bus_addr < 0)
+                                bb_error_msg_and_die("no address given in '%s'", *argv);
+                }
+
+                msgs[nmsgs].addr = bus_addr;
+                msgs[nmsgs].flags = flags;
+                msgs[nmsgs].len = len;
+                if (len)
+                        msgs[nmsgs].buf = xzalloc(len);
+
+                if (!(flags & I2C_M_RD)) {
+                        /* Consume DATA arg(s) */
+                        unsigned buf_idx = 0;
+
+                        while (buf_idx < len) {
+                                uint8_t data8;
+                                unsigned long data;
+
+                                arg_ptr = *++argv;
+                                if (!arg_ptr)
+                                        bb_show_usage();
+                                data = strtoul(arg_ptr, &end, 0);
+                                if (data > 0xff || arg_ptr == end)
+                                        bb_error_msg_and_die("invalid data byte '%s'", *argv);
+
+                                data8 = data;
+                                while (buf_idx < len) {
+                                        msgs[nmsgs].buf[buf_idx++] = data8;
+                                        if (!*end)
+                                                break;
+                                        switch (*end) {
+                                        /* Pseudo randomness (8 bit AXR with a=13 and b=27) */
+                                        case 'p':
+                                                data8 = (data8 ^ 27) + 13;
+                                                data8 = (data8 << 1) | (data8 >> 7);
+                                                break;
+                                        case '+': data8++; break;
+                                        case '-': data8--; break;
+                                        case '=': break;
+                                        default:
+                                                bb_error_msg_and_die("invalid data byte suffix: '%s'",
+                                                                     *argv);
+                                        }
+                                }
+                        }
+                }
+                nmsgs++;
+        }
+
+        if (!(opts & opt_y))
+                confirm_action(bus_addr, 0, 0, 0);
+
+        rdwr.msgs = msgs;
+        rdwr.nmsgs = nmsgs;
+        nmsgs_sent = ioctl_or_perror_and_die(fd, I2C_RDWR, &rdwr, "I2C_RDWR");
+        if (nmsgs_sent < nmsgs)
+                bb_error_msg("warning: only %u/%u messages sent", nmsgs_sent, nmsgs);
+
+        for (i = 0; i < nmsgs_sent; i++) {
+                if (msgs[i].len != 0 && (msgs[i].flags & I2C_M_RD)) {
+                        int j;
+                        for (j = 0; j < msgs[i].len - 1; j++)
+                                printf("0x%02x ", msgs[i].buf[j]);
+                        /* Print final byte with newline */
+                        printf("0x%02x\n", msgs[i].buf[j]);
+                }
+        }
+
+# if ENABLE_FEATURE_CLEAN_UP
+        close(fd);
+        for (i = 0; i < nmsgs; i++)
+                free(msgs[i].buf);
+# endif
+
+        return 0;
+}
+#endif /* ENABLE_I2CTRANSFER */