astlpc: Provide KCS device path as a binding argument

Currently astlpc binding expects a '/dev/mctp0' device in the system
for the KCS communication. This device is a symbolic link to the
real '/dev/raw-kcsX' device, created by the udev rules populated by the
build system.
This approach is not ideal since the build system populates udev rules
for the KCS3 and KCS4 channels simultaneously and for these channels
only. This means that there are some design limitations for the MCTP
communication. It is only possible on KCS3 or KCS4 channel, and if one
of these channels is used, the other one must be disabled.
To make design more flexible get rid of all the udev rules and provide
'/dev/raw-kcsX' device path as an argument to the binding
initialization code.

Change-Id: I505e44280636c83b59669b314f60279b371d0403
Signed-off-by: Konstantin Aladyshev <[email protected]>

Author: Kostr

Makefile.am

@@ -33,11 +33,6 @@ utils_mctp_demux_daemon_CFLAGS = $(pcap_CFLAGS)
 
 pkgconfig_DATA = libmctp.pc
 
-if LIBMCTP_UDEV_RAW_KCS
-udevrules_DATA = udev/rules.d/mctp0-raw-kcs3.rules \
-		 udev/rules.d/mctp0-raw-kcs4.rules
-endif
-
 if AUTOCONF_CODE_COVERAGE_2019_01_06
 include $(top_srcdir)/aminclude_static.am
 clean-local: code-coverage-clean

astlpc.c

@@ -36,7 +36,6 @@
 #include <linux/aspeed-lpc-ctrl.h>
 
 /* kernel interface */
-static const char *kcs_path = "/dev/mctp0";
 static const char *lpc_path = "/dev/aspeed-lpc-ctrl";
 
 #endif
@@ -1410,7 +1409,8 @@ static int mctp_astlpc_init_fileio_lpc(struct mctp_binding_astlpc *astlpc)
 	return rc;
 }
 
-static int mctp_astlpc_init_fileio_kcs(struct mctp_binding_astlpc *astlpc)
+static int mctp_astlpc_init_fileio_kcs(struct mctp_binding_astlpc *astlpc,
+				       const char *kcs_path)
 {
 	astlpc->kcs_fd = open(kcs_path, O_RDWR);
 	if (astlpc->kcs_fd < 0)
@@ -1461,7 +1461,7 @@ int mctp_astlpc_init_pollfd(struct mctp_binding_astlpc *astlpc,
 	return 0;
 }
 
-struct mctp_binding_astlpc *mctp_astlpc_init_fileio(void)
+struct mctp_binding_astlpc *mctp_astlpc_init_fileio(const char *kcs_path)
 {
 	struct mctp_binding_astlpc *astlpc;
 	int rc;
@@ -1489,7 +1489,7 @@ struct mctp_binding_astlpc *mctp_astlpc_init_fileio(void)
 		return NULL;
 	}
 
-	rc = mctp_astlpc_init_fileio_kcs(astlpc);
+	rc = mctp_astlpc_init_fileio_kcs(astlpc, kcs_path);
 	if (rc) {
 		free(astlpc);
 		return NULL;
@@ -1498,7 +1498,8 @@ struct mctp_binding_astlpc *mctp_astlpc_init_fileio(void)
 	return astlpc;
 }
 #else
-struct mctp_binding_astlpc *mctp_astlpc_init_fileio(void)
+struct mctp_binding_astlpc *
+mctp_astlpc_init_fileio(const char *kcs_path __unused)
 {
 	mctp_prlog(MCTP_LOG_ERR, "%s: Missing support for file IO", __func__);
 	return NULL;

configure.ac

@@ -21,12 +21,6 @@ AC_CHECK_HEADERS_ONCE([unistd.h fcntl.h])
 # pkg-config
 PKG_PROG_PKG_CONFIG
 PKG_INSTALLDIR
-PKG_CHECK_MODULES(udev,
-                  udev,
-                  [PKG_CHECK_VAR(udevdir, udev, udevdir)],
-                  [])
-
-AC_SUBST([udevrulesdir], [$udevdir/rules.d])
 
 AC_ARG_ENABLE([capture],
               [AC_HELP_STRING([--enable-capture],
@@ -41,11 +35,6 @@ AC_SUBST([pcap_CFLAGS])
 AC_SUBST([pcap_LIBS])
 AM_CONDITIONAL([HAVE_PCAP], [test "x$enable_capture" = "xyes"])
 
-AC_ARG_ENABLE([astlpc-raw-kcs],
-              [AS_HELP_STRING([--enable-astlpc-raw-kcs],
-                              [Use udev rules to symlink raw-kcs device nodes for the astlpc binding])])
-AM_CONDITIONAL([LIBMCTP_UDEV_RAW_KCS], [test -n "$udevdir" -a "x$enable_astlpc_raw_kcs" = "xyes"])
-
 AC_ARG_WITH([systemdsystemunitdir],
      [AS_HELP_STRING([--with-systemdsystemunitdir=DIR], [Directory for systemd service files])],
      [],
@@ -174,6 +163,5 @@ m4_ifdef([_AX_CODE_COVERAGE_RULES],
     [AM_CONDITIONAL(AUTOCONF_CODE_COVERAGE_2019_01_06, [false])])
 AX_ADD_AM_MACRO_STATIC([])
 
-AC_CONFIG_FILES([Makefile libmctp.pc udev/rules.d/mctp0-raw-kcs3.rules
-                 udev/rules.d/mctp0-raw-kcs4.rules])
+AC_CONFIG_FILES([Makefile libmctp.pc])
 AC_OUTPUT

libmctp-astlpc.h

@@ -45,7 +45,7 @@ bool mctp_astlpc_tx_done(struct mctp_binding_astlpc *astlpc);
 int mctp_astlpc_poll(struct mctp_binding_astlpc *astlpc);
 
 /* fileio-based interface */
-struct mctp_binding_astlpc *mctp_astlpc_init_fileio(void);
+struct mctp_binding_astlpc *mctp_astlpc_init_fileio(const char *kcs_path);
 
 struct pollfd;
 int mctp_astlpc_init_pollfd(struct mctp_binding_astlpc *astlpc,

udev/rules.d/mctp0-raw-kcs3.rules.in

@@ -211,13 +211,16 @@ static int binding_astlpc_init(struct mctp *mctp, struct binding *binding,
 			       char *const *params __attribute__((unused)))
 {
 	struct mctp_binding_astlpc *astlpc;
+	const char *path;
 
-	if (n_params) {
-		warnx("astlpc binding does not accept parameters");
+	if (n_params != 1) {
+		warnx("astlpc binding requires kcs device param");
 		return -1;
 	}
 
-	astlpc = mctp_astlpc_init_fileio();
+	path = params[0];
+
+	astlpc = mctp_astlpc_init_fileio(path);
 	if (!astlpc) {
 		warnx("could not initialise astlpc binding");
 		return -1;