ACPI / tools: Introduce ec_access.c - tool to access the EC

This userspace tool accesses the EC through the ec_sys debug driver
(through /sys/kernel/debug/ec/ec0/io).

The EC command/data registers cannot be accessed directly, because they
may be manipulated by the AML interpreter in parallel.

The ec_sys driver synchronizes user space (debug) access with the AML
interpreter.
Signed-off-by: Thomas Renninger <trenn@suse.de>
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

tools/power/acpi/Makefile

@@ -19,6 +19,8 @@ OUTDIR := $(shell cd $(OUTPUT) && /bin/pwd)
 $(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist))
 endif
 
+SUBDIRS = tools/ec
+
 # --- CONFIGURATION BEGIN ---
 
 # Set the following to `true' to make a unstripped, unoptimized

tools/power/acpi/tools/ec/Makefile

+ec_access: ec_access.o
+	$(ECHO) "  LD      " $@
+	$(QUIET) $(LD) $(CFLAGS) $(LDFLAGS) $< -o $@
+	$(QUIET) $(STRIPCMD) $@
+
+%.o: %.c
+	$(ECHO) "  CC      " $@
+	$(QUIET) $(CC) -c $(CFLAGS) -o $@ $<
+
+all: ec_access
+
+install:
+	$(INSTALL) -d $(DESTDIR)${sbindir}
+	$(INSTALL_PROGRAM) ec_access $(DESTDIR)${sbindir}
+
+uninstall:
+	- rm -f $(DESTDIR)${sbindir}/ec_access
+
+clean:
+	-rm -f $(OUTPUT)ec_access
+
+.PHONY: all install uninstall

tools/power/acpi/tools/ec/ec_access.c

+/*
+ * ec_access.c
+ *
+ * Copyright (C) 2010 SUSE Linux Products GmbH
+ * Author:
+ *      Thomas Renninger <trenn@suse.de>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ */
+
+#include <fcntl.h>
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <libgen.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <stdint.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+
+#define EC_SPACE_SIZE 256
+#define SYSFS_PATH "/sys/kernel/debug/ec/ec0/io"
+
+/* TBD/Enhancements:
+   - Provide param for accessing different ECs (not supported by kernel yet)
+*/
+
+static int read_mode = -1;
+static int sleep_time;
+static int write_byte_offset = -1;
+static int read_byte_offset = -1;
+static uint8_t write_value = -1;
+
+void usage(char progname[], int exit_status)
+{
+	printf("Usage:\n");
+	printf("1) %s -r [-s sleep]\n", basename(progname));
+	printf("2) %s -b byte_offset\n", basename(progname));
+	printf("3) %s -w byte_offset -v value\n\n", basename(progname));
+
+	puts("\t-r [-s sleep]      : Dump EC registers");
+	puts("\t                     If sleep is given, sleep x seconds,");
+	puts("\t                     re-read EC registers and show changes");
+	puts("\t-b offset          : Read value at byte_offset (in hex)");
+	puts("\t-w offset -v value : Write value at byte_offset");
+	puts("\t-h                 : Print this help\n\n");
+	puts("Offsets and values are in hexadecimal number sytem.");
+	puts("The offset and value must be between 0 and 0xff.");
+	exit(exit_status);
+}
+
+void parse_opts(int argc, char *argv[])
+{
+	int c;
+
+	while ((c = getopt(argc, argv, "rs:b:w:v:h")) != -1) {
+
+		switch (c) {
+		case 'r':
+			if (read_mode != -1)
+				usage(argv[0], EXIT_FAILURE);
+			read_mode = 1;
+			break;
+		case 's':
+			if (read_mode != -1 && read_mode != 1)
+				usage(argv[0], EXIT_FAILURE);
+
+			sleep_time = atoi(optarg);
+			if (sleep_time <= 0) {
+				sleep_time = 0;
+				usage(argv[0], EXIT_FAILURE);
+				printf("Bad sleep time: %s\n", optarg);
+			}
+			break;
+		case 'b':
+			if (read_mode != -1)
+				usage(argv[0], EXIT_FAILURE);
+			read_mode = 1;
+			read_byte_offset = strtoul(optarg, NULL, 16);
+			break;
+		case 'w':
+			if (read_mode != -1)
+				usage(argv[0], EXIT_FAILURE);
+			read_mode = 0;
+			write_byte_offset = strtoul(optarg, NULL, 16);
+			break;
+		case 'v':
+			write_value = strtoul(optarg, NULL, 16);
+			break;
+		case 'h':
+			usage(argv[0], EXIT_SUCCESS);
+		default:
+			fprintf(stderr, "Unknown option!\n");
+			usage(argv[0], EXIT_FAILURE);
+		}
+	}
+	if (read_mode == 0) {
+		if (write_byte_offset < 0 ||
+		    write_byte_offset >= EC_SPACE_SIZE) {
+			fprintf(stderr, "Wrong byte offset 0x%.2x, valid: "
+				"[0-0x%.2x]\n",
+				write_byte_offset, EC_SPACE_SIZE - 1);
+			usage(argv[0], EXIT_FAILURE);
+		}
+		if (write_value < 0 ||
+		    write_value >= 255) {
+			fprintf(stderr, "Wrong byte offset 0x%.2x, valid:"
+				"[0-0xff]\n", write_byte_offset);
+			usage(argv[0], EXIT_FAILURE);
+		}
+	}
+	if (read_mode == 1 && read_byte_offset != -1) {
+		if (read_byte_offset < -1 ||
+		    read_byte_offset >= EC_SPACE_SIZE) {
+			fprintf(stderr, "Wrong byte offset 0x%.2x, valid: "
+				"[0-0x%.2x]\n",
+				read_byte_offset, EC_SPACE_SIZE - 1);
+			usage(argv[0], EXIT_FAILURE);
+		}
+	}
+	/* Add additional parameter checks here */
+}
+
+void dump_ec(int fd)
+{
+	char buf[EC_SPACE_SIZE];
+	char buf2[EC_SPACE_SIZE];
+	int byte_off, bytes_read;
+
+	bytes_read = read(fd, buf, EC_SPACE_SIZE);
+
+	if (bytes_read == -1)
+		err(EXIT_FAILURE, "Could not read from %s\n", SYSFS_PATH);
+
+	if (bytes_read != EC_SPACE_SIZE)
+		fprintf(stderr, "Could only read %d bytes\n", bytes_read);
+
+	printf("     00  01  02  03  04  05  06  07  08  09  0A  0B  0C  0D  0E  0F");
+	for (byte_off = 0; byte_off < bytes_read; byte_off++) {
+		if ((byte_off % 16) == 0)
+			printf("\n%.2X: ", byte_off);
+		printf(" %.2x ", (uint8_t)buf[byte_off]);
+	}
+	printf("\n");
+
+	if (!sleep_time)
+		return;
+
+	printf("\n");
+	lseek(fd, 0, SEEK_SET);
+	sleep(sleep_time);
+
+	bytes_read = read(fd, buf2, EC_SPACE_SIZE);
+
+	if (bytes_read == -1)
+		err(EXIT_FAILURE, "Could not read from %s\n", SYSFS_PATH);
+
+	if (bytes_read != EC_SPACE_SIZE)
+		fprintf(stderr, "Could only read %d bytes\n", bytes_read);
+
+	printf("     00  01  02  03  04  05  06  07  08  09  0A  0B  0C  0D  0E  0F");
+	for (byte_off = 0; byte_off < bytes_read; byte_off++) {
+		if ((byte_off % 16) == 0)
+			printf("\n%.2X: ", byte_off);
+
+		if (buf[byte_off] == buf2[byte_off])
+			printf(" %.2x ", (uint8_t)buf2[byte_off]);
+		else
+			printf("*%.2x ", (uint8_t)buf2[byte_off]);
+	}
+	printf("\n");
+}
+
+void read_ec_val(int fd, int byte_offset)
+{
+	uint8_t buf;
+	int error;
+
+	error = lseek(fd, byte_offset, SEEK_SET);
+	if (error != byte_offset)
+		err(EXIT_FAILURE, "Cannot set offset to 0x%.2x", byte_offset);
+
+	error = read(fd, &buf, 1);
+	if (error != 1)
+		err(EXIT_FAILURE, "Could not read byte 0x%.2x from %s\n",
+		    byte_offset, SYSFS_PATH);
+	printf("0x%.2x\n", buf);
+	return;
+}
+
+void write_ec_val(int fd, int byte_offset, uint8_t value)
+{
+	int error;
+
+	error = lseek(fd, byte_offset, SEEK_SET);
+	if (error != byte_offset)
+		err(EXIT_FAILURE, "Cannot set offset to 0x%.2x", byte_offset);
+
+	error = write(fd, &value, 1);
+	if (error != 1)
+		err(EXIT_FAILURE, "Cannot write value 0x%.2x to offset 0x%.2x",
+		    value, byte_offset);
+}
+
+int main(int argc, char *argv[])
+{
+	int file_mode = O_RDONLY;
+	int fd;
+
+	parse_opts(argc, argv);
+
+	if (read_mode == 0)
+		file_mode = O_WRONLY;
+	else if (read_mode == 1)
+		file_mode = O_RDONLY;
+	else
+		usage(argv[0], EXIT_FAILURE);
+
+	fd = open(SYSFS_PATH, file_mode);
+	if (fd == -1)
+		err(EXIT_FAILURE, "%s", SYSFS_PATH);
+
+	if (read_mode)
+		if (read_byte_offset == -1)
+			dump_ec(fd);
+		else if (read_byte_offset < 0 ||
+			 read_byte_offset >= EC_SPACE_SIZE)
+			usage(argv[0], EXIT_FAILURE);
+		else
+			read_ec_val(fd, read_byte_offset);
+	else
+		write_ec_val(fd, write_byte_offset, write_value);
+	close(fd);
+
+	exit(EXIT_SUCCESS);
+}