external: Add "lpc" tool

This is a little front-end to the lpc debugfs files to access
the LPC bus from userspace on the host.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Stewart Smith <stewart@linux.ibm.com>

external/lpc/Makefile

@@ -0,0 +1,6 @@
+all: lpc
+
+lpc: lpc.c
+	$(CC) -o $@ $^
+
+clean: rm -rf *.[od] lpc

external/lpc/lpc.c

@@ -0,0 +1,187 @@
+/* Copyright 2014-2016 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *	http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.
+ * See the License for the specific language governing permissions and
+ * imitations under the License.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <byteswap.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <getopt.h>
+#include <limits.h>
+#include <arpa/inet.h>
+#include <assert.h>
+#include <endian.h>
+#include <byteswap.h>
+
+#define SYSFS_PREFIX "/sys/kernel/debug/powerpc/lpc"
+
+int main(int argc, char *argv[])
+{
+	char		path[256];
+	char		*dot;
+	char		*eq;
+	int		fd, size = 4;
+	bool		do_write = false;
+	bool		big_endian = false;
+	uint32_t	addr, val;
+	ssize_t		rc;
+
+	if (argc < 3) {
+		printf("Usage: %s <space> <addr>[.lLwWbBd[,size]][=value]\n", argv[0]);
+		return 0;
+	}
+
+	eq = strchr(argv[2], '=');
+	if (eq) {
+		do_write = true;
+		val = strtoul(eq + 1, NULL, 0);
+		*eq = 0;
+	}
+	dot = strchr(argv[2], '.');
+	if (dot) {
+		*(dot++) = 0;
+		switch(*dot) {
+		case 'L':
+			big_endian  = true;
+		case 'l':
+			break;
+		case 'W':
+			big_endian  = true;
+		case 'w':
+			size = 2;
+			break;
+		case 'B':
+			big_endian  = true;
+		case 'b':
+			size = 1;
+			break;
+		default:
+			fprintf(stderr, "Invalid size specifier\n");
+			exit(1);
+		}
+	}
+	addr = strtoul(argv[2], NULL, 0);
+
+	memset(path, 0, sizeof(path));
+	snprintf(path, 255, SYSFS_PREFIX "/%s", argv[1]);
+	fd = open(path, O_RDWR);
+	if (fd < 0) {
+		perror("Failed to open sysfs file");
+		exit(1);
+	}
+
+	lseek(fd, addr, SEEK_SET);
+	if (do_write)  {
+		uint8_t v8;
+		uint16_t v16;
+		uint32_t v32;
+
+		switch(size) {
+		case 1:
+			val &= 0xff;
+			v8 = val;
+			rc = write(fd, &v8, 1);
+			if (rc != 1) {
+				perror("Failed to write to LPC");
+				exit(1);
+			}
+			printf("[%s] W 0x%08x.%c=0x%02x\n",
+			       argv[1], addr, big_endian ? 'B' : 'b', val);
+			break;
+		case 2:
+			val &= 0xffff;
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+			v16 = big_endian ? bswap_16(val) : val;
+#else
+			v16 = big_endian ? val : bswap_16(val);
+#endif
+			rc = write(fd, &v16, 2);
+			if (rc != 2) {
+				perror("Failed to write to LPC");
+				exit(1);
+			}
+			printf("[%s] W 0x%08x.%c=0x%04x\n",
+			       argv[1], addr, big_endian ? 'W' : 'w', val);
+			break;
+		default:
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+			v32 = big_endian ? bswap_32(val) : val;
+#else
+			v32 = big_endian ? val : bswap_32(val);
+#endif
+			rc = write(fd, &v32, 4);
+			if (rc != 4) {
+				perror("Failed to write to LPC");
+				exit(1);
+			}
+			printf("[%s] W 0x%08x.%c=0x%08x\n",
+			       argv[1], addr, big_endian ? 'L' : 'l', val);
+			break;
+		}
+	} else {
+		uint8_t v8;
+		uint16_t v16;
+		uint32_t v32;
+
+		switch(size) {
+		case 1:
+			rc = read(fd, &v8, 1);
+			if (rc != 1) {
+				perror("Failed to read from LPC");
+				exit(1);
+			}
+			printf("[%s] R 0x%08x.%c=0x%02x\n", argv[1], addr,
+			       big_endian ? 'B' : 'b', v8);
+			break;
+		case 2:
+			rc = read(fd, &v16, 2);
+			if (rc != 2) {
+				perror("Failed to read from LPC");
+				exit(1);
+			}
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+			v16 = big_endian ? bswap_16(v16) : v16;
+#else
+			v16 = big_endian ? v16 : bswap_16(v16);
+#endif
+			printf("[%s] R 0x%08x.%c=0x%04x\n", argv[1], addr,
+			       big_endian ? 'W' : 'w', v16);
+			break;
+		default:
+			rc = read(fd, &v32, 4);
+			if (rc != 4) {
+				perror("Failed to read from LPC");
+				exit(1);
+			}
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+			v32 = big_endian ? bswap_32(v32) : v32;
+#else
+			v32 = big_endian ? v32 : bswap_32(v32);
+#endif
+			printf("[%s] R 0x%08x.%c=0x%08x\n", argv[1], addr,
+			       big_endian ? 'L' : 'l', v32);
+			break;
+		}
+	}
+	return 0;
+}