external/common: Add POWERPC code reenable building pflash for POWER

As per commit to create the external/common code, this commit introduces
the POWER arch compatibility flash reading code.

This commit actually should cause no functional change to pflash (it won't
be able to access the BMC flash if it ever could), however rather than
accessing the flash via the debugfs opal_lpc_{read,write} interface it will
access it though the MTD interface provided by linux and importantly skiboot.

Not only does using the MTD interface allows applications to treat it like
flash despite the fact that they are talking through several layers of
abstraction. Using passing through skiboot means that all the access to the
flash from the Power8 can be protected from concurrent access.

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

3 files changed, 233 insertions, 0 deletions

diff --git a/external/common/arch_flash_powerpc.c b/external/common/arch_flash_powerpc.c
new file mode 100644
index 00000000..53c14ce1
--- /dev/null
+++ b/external/common/arch_flash_powerpc.c
@@ -0,0 +1,228 @@
+/* Copyright 2013-2015 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
+ * limitations under the License.
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <stdbool.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <string.h>
+
+#include <libflash/file.h>
+
+#include "arch_flash.h"
+
+#define FDT_FLASH_PATH "/proc/device-tree/chosen/ibm,system-flash"
+#define SYSFS_MTD_PATH "/sys/class/mtd"
+
+static inline void hint_root(void)
+{
+	fprintf(stderr, "Do you have permission? Are you root?\n");
+}
+
+static int get_dev_attr(const char *dev, const char *attr_file, uint32_t *attr)
+{
+	char *dev_path = NULL;
+	int fd, rc;
+
+	/*
+	 * Needs to be large enough to hold at most uint32_t represented as a
+	 * string in hex with leading 0x
+	 */
+	char attr_buf[10];
+
+	rc = asprintf(&dev_path, "%s/%s/%s", SYSFS_MTD_PATH, dev, attr_file);
+	if (rc < 0) {
+		dev_path = NULL;
+		goto out;
+	}
+
+	fd = open(dev_path, O_RDONLY);
+	if (fd == -1)
+		goto out;
+
+	rc = read(fd, attr_buf, sizeof(attr_buf));
+	close(fd);
+	if (rc == -1)
+		goto out;
+
+	if (attr)
+		*attr = strtol(attr_buf, NULL, 0);
+
+	free(dev_path);
+	return 0;
+
+out:
+	free(dev_path);
+	fprintf(stderr, "Couldn't get MTD attribute '%s' from '%s'\n", dev, attr_file);
+	return -1;
+}
+
+static int get_dev_mtd(const char *fdt_flash_path, char **mtd_path)
+{
+	struct dirent **namelist;
+	char fdt_node_path[PATH_MAX];
+	int count, i, rc, fd;
+	bool done;
+
+	if (!fdt_flash_path)
+		return -1;
+
+	fd = open(fdt_flash_path, O_RDONLY);
+	if (fd == -1) {
+		fprintf(stderr, "Couldn't open '%s' FDT attribute to determine which flash device to use\n",
+				fdt_flash_path);
+		fprintf(stderr, "Does your skiboot new enough to expose the flash through the device tree?\n");
+		hint_root();
+		return -1;
+	}
+
+	rc = read(fd, fdt_node_path, sizeof(fdt_node_path));
+	close(fd);
+	if (rc == -1) {
+		fprintf(stderr, "Couldn't read flash FDT node from '%s'\n", fdt_flash_path);
+		hint_root();
+		return -1;
+	}
+
+	count = scandir(SYSFS_MTD_PATH, &namelist, NULL, alphasort);
+	if (count == -1) {
+		fprintf(stderr, "Couldn't scan '%s' for MTD\n", SYSFS_MTD_PATH);
+		hint_root();
+		return -1;
+	}
+
+	rc = 0;
+	done = false;
+	for (i = 0; i < count; i++) {
+		struct dirent *dirent;
+		char *dev_path;
+		char fdt_node_path_tmp[PATH_MAX];
+
+		dirent = namelist[i];
+
+		/*
+		 * The call to asprintf must happen last as when it succeeds it
+		 * will allocate dev_path
+		 */
+		if (dirent->d_name[0] == '.' || rc || done ||
+			asprintf(&dev_path, "%s/%s/device/of_node", SYSFS_MTD_PATH, dirent->d_name) < 0) {
+			free(namelist[i]);
+			continue;
+		}
+
+		rc = readlink(dev_path, fdt_node_path_tmp, sizeof(fdt_node_path_tmp) - 1);
+		free(dev_path);
+		if (rc == -1) {
+			/*
+			 * This might fail because it could not exist if the system has flash
+			 * devices that present as mtd but don't have corresponding FDT
+			 * nodes, just continue silently.
+			 */
+			free(namelist[i]);
+			/* Should still try the next dir so reset rc */
+			rc = 0;
+			continue;
+		}
+		fdt_node_path_tmp[rc] = '\0';
+
+		if (strstr(fdt_node_path_tmp, fdt_node_path)) {
+			uint32_t flags, size;
+
+			/*
+			 * size and flags could perhaps have be gotten another way but this
+			 * method is super unlikely to fail so it will do.
+			 */
+
+			/* Check to see if device is writeable */
+			rc = get_dev_attr(dirent->d_name, "flags", &flags);
+			if (rc) {
+				free(namelist[i]);
+				continue;
+			}
+
+			/* Get the size of the mtd device while we're at it */
+			rc = get_dev_attr(dirent->d_name, "size", &size);
+			if (rc) {
+				free(namelist[i]);
+				continue;
+			}
+
+			rc = asprintf(&dev_path, "/dev/%s", dirent->d_name);
+			if (rc < 0) {
+				free(namelist[i]);
+				continue;
+			}
+			rc = 0;
+			*mtd_path = dev_path;
+			done = true;
+		}
+		free(namelist[i]);
+	}
+	free(namelist);
+
+	if (!done) {
+		fprintf(stderr, "Couldn't find '%s' corresponding MTD\n", fdt_flash_path);
+		fprintf(stderr, "Is your kernel new enough to expose MTD?\n");
+	}
+
+	/* explicit negative value so as to not return a libflash code */
+	return done ? rc : -1;
+}
+
+static struct blocklevel_device *arch_init_blocklevel(const char *file)
+{
+	int rc;
+	struct blocklevel_device *new_bl = NULL;
+	char *real_file;
+
+	if (!file) {
+		rc = get_dev_mtd(FDT_FLASH_PATH, &real_file);
+		if (rc)
+			return NULL;
+	}
+
+	file_init_path(file ? file : real_file, NULL, &new_bl);
+	return new_bl;
+}
+
+/* Skiboot will worry about this for us */
+int arch_flash_set_wrprotect(struct blocklevel_device *bl, int set)
+{
+	return 0;
+}
+
+int arch_flash_init(struct blocklevel_device **r_bl, const char *file)
+{
+	struct blocklevel_device *new_bl;
+
+	new_bl = arch_init_blocklevel(file);
+	if (!new_bl)
+		return -1;
+
+	*r_bl = new_bl;
+	return 0;
+}
+
+void arch_flash_close(struct blocklevel_device *bl, const char *file)
+{
+	file_exit_close(bl);
+}
diff --git a/external/common/arch_flash_powerpc_io.h b/external/common/arch_flash_powerpc_io.h
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/external/common/arch_flash_powerpc_io.h
diff --git a/external/pflash/rules.mk b/external/pflash/rules.mk
index 8cd8c738..6671f15f 100644
--- a/external/pflash/rules.mk
+++ b/external/pflash/rules.mk
@@ -4,8 +4,13 @@ ifeq ($(ARCH),ARCH_ARM)
 arch = arm
 ARCH_OBJS = common/arch_flash_common.o common/arch_flash_arm.o ast-sf-ctrl.o
 else
+ifeq ($(ARCH),ARCH_POWERPC)
+arch = powerpc
+ARCH_OBJS = common/arch_flash_common.o common/arch_flash_powerpc.o
+else
 $(error Unsupported architecture $(ARCH))
 endif
+endif
 
 .DEFAULT_GOAL := all