Add extcsd write-protect read/write code
This was posted to linux-mmc@ by Johan Rudholm.
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/Makefile b/Makefile
index 276e996..63f97b5 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
CC = gcc
AM_CFLAGS = -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2
CFLAGS = -g -O0
-objects = mmc.o
+objects = mmc.o mmc_cmds.h
CHECKFLAGS= -Wall -Werror -Wuninitialized -Wundef
diff --git a/mmc.h b/mmc.h
new file mode 100644
index 0000000..8540f3d
--- /dev/null
+++ b/mmc.h
@@ -0,0 +1,61 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <asm-generic/int-ll64.h>
+#include <linux/mmc/ioctl.h>
+#include <linux/major.h>
+#include <stdio.h>
+
+#define CHECK(expr, msg, err_stmt) { if (expr) { fprintf(stderr, msg); err_stmt; } }
+
+/* From kernel linux/mmc/mmc.h */
+#define MMC_SWITCH 6 /* ac [31:0] See below R1b */
+#define MMC_SEND_EXT_CSD 8 /* adtc R1 */
+#define MMC_SWITCH_MODE_WRITE_BYTE 0x03 /* Set target to value */
+
+/*
+ * EXT_CSD fields
+ */
+#define EXT_CSD_BOOT_WP 173 /* R/W */
+#define EXT_CSD_PART_SWITCH_TIME 199 /* RO */
+
+/*
+ * EXT_CSD field definitions
+ */
+#define EXT_CSD_CMD_SET_NORMAL (1<<0)
+#define EXT_CSD_BOOT_WP_B_PWR_WP_DIS (0x40)
+#define EXT_CSD_BOOT_WP_B_PERM_WP_DIS (0x10)
+#define EXT_CSD_BOOT_WP_B_PERM_WP_EN (0x04)
+#define EXT_CSD_BOOT_WP_B_PWR_WP_EN (0x01)
+
+/* From kernel linux/mmc/core.h */
+#define MMC_RSP_PRESENT (1 << 0)
+#define MMC_RSP_136 (1 << 1) /* 136 bit response */
+#define MMC_RSP_CRC (1 << 2) /* expect valid crc */
+#define MMC_RSP_BUSY (1 << 3) /* card may send busy */
+#define MMC_RSP_OPCODE (1 << 4) /* response contains opcode */
+
+#define MMC_CMD_AC (0 << 5)
+#define MMC_CMD_ADTC (1 << 5)
+
+#define MMC_RSP_SPI_S1 (1 << 7) /* one status byte */
+#define MMC_RSP_SPI_BUSY (1 << 10) /* card may send busy */
+
+#define MMC_RSP_SPI_R1 (MMC_RSP_SPI_S1)
+#define MMC_RSP_SPI_R1B (MMC_RSP_SPI_S1|MMC_RSP_SPI_BUSY)
+
+#define MMC_RSP_R1 (MMC_RSP_PRESENT|MMC_RSP_CRC|MMC_RSP_OPCODE)
+#define MMC_RSP_R1B (MMC_RSP_PRESENT|MMC_RSP_CRC|MMC_RSP_OPCODE|MMC_RSP_BUSY)
diff --git a/mmc_cmds.c b/mmc_cmds.c
new file mode 100644
index 0000000..82fd016
--- /dev/null
+++ b/mmc_cmds.c
@@ -0,0 +1,158 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <libgen.h>
+#include <limits.h>
+#include <uuid/uuid.h>
+#include <ctype.h>
+
+#include "mmc.h"
+#include "mmc_cmds.h"
+
+int read_extcsd(int fd, __u8 *ext_csd)
+{
+ int ret = 0;
+ struct mmc_ioc_cmd idata;
+ memset(&idata, 0, sizeof(idata));
+ memset(ext_csd, 0, sizeof(__u8) * 512);
+ idata.write_flag = 0;
+ idata.opcode = MMC_SEND_EXT_CSD;
+ idata.arg = 0;
+ idata.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
+ idata.blksz = 512;
+ idata.blocks = 1;
+ mmc_ioc_cmd_set_data(idata, ext_csd);
+
+ ret = ioctl(fd, MMC_IOC_CMD, &idata);
+ if (ret)
+ perror("ioctl");
+
+ return ret;
+}
+
+int write_extcsd_value(int fd, __u8 index, __u8 value)
+{
+ int ret = 0;
+ struct mmc_ioc_cmd idata;
+
+ memset(&idata, 0, sizeof(idata));
+ idata.write_flag = 1;
+ idata.opcode = MMC_SWITCH;
+ idata.arg = (MMC_SWITCH_MODE_WRITE_BYTE << 24) |
+ (index << 16) |
+ (value << 8) |
+ EXT_CSD_CMD_SET_NORMAL;
+ idata.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
+
+ ret = ioctl(fd, MMC_IOC_CMD, &idata);
+ if (ret)
+ perror("ioctl");
+
+ return ret;
+}
+
+int do_read_extcsd(int nargs, char **argv)
+{
+ __u8 ext_csd[512];
+ int fd, ret;
+ char *device;
+
+ CHECK(nargs != 2, "Usage: mmc </path/to/mmcblkX>\n", exit(1));
+
+ device = argv[1];
+
+ fd = open(device, O_RDWR);
+ if (fd < 0) {
+ perror("open");
+ exit(1);
+ }
+
+ ret = read_extcsd(fd, ext_csd);
+ if (ret) {
+ fprintf(stderr, "Could not read EXT_CSD from %s\n", device);
+ exit(1);
+ }
+
+ printf("Power ro locking: ");
+ if (ext_csd[EXT_CSD_BOOT_WP] & EXT_CSD_BOOT_WP_B_PWR_WP_DIS)
+ printf("not possible\n");
+ else
+ printf("possible\n");
+
+ printf("Permanent ro locking: ");
+ if (ext_csd[EXT_CSD_BOOT_WP] & EXT_CSD_BOOT_WP_B_PERM_WP_DIS)
+ printf("not possible\n");
+ else
+ printf("possible\n");
+
+ printf("ro lock status: ");
+ if (ext_csd[EXT_CSD_BOOT_WP] & EXT_CSD_BOOT_WP_B_PWR_WP_EN)
+ printf("locked until next power on\n");
+ else if (ext_csd[EXT_CSD_BOOT_WP] &
+ EXT_CSD_BOOT_WP_B_PERM_WP_EN)
+ printf("locked permanently\n");
+ else
+ printf("not locked\n");
+
+ return ret;
+}
+
+int do_write_extcsd(int nargs, char **argv)
+{
+ __u8 ext_csd[512], value;
+ int fd, ret;
+ char *device;
+
+ if (nargs != 2) {
+ fprintf (stderr, "Usage: %s </path/to/mmcblkX>\n",
+ argv[0]);
+ exit (1);
+ }
+ device = argv[1];
+
+ fd = open(device, O_RDWR);
+ if (fd < 0) {
+ perror("open");
+ exit(1);
+ }
+
+ ret = read_extcsd(fd, ext_csd);
+ if (ret) {
+ fprintf(stderr, "Could not read EXT_CSD from %s\n", device);
+ exit(1);
+ }
+
+ value = ext_csd[EXT_CSD_BOOT_WP] |
+ EXT_CSD_BOOT_WP_B_PWR_WP_EN;
+ ret = write_extcsd_value(fd, EXT_CSD_BOOT_WP, value);
+ if (ret) {
+ fprintf(stderr, "Could not write 0x%02x to "
+ "EXT_CSD[%d] in %s\n",
+ value, EXT_CSD_BOOT_WP, device);
+ exit(1);
+ }
+
+ return ret;
+}
diff --git a/mmc_cmds.h b/mmc_cmds.h
new file mode 100644
index 0000000..1b28051
--- /dev/null
+++ b/mmc_cmds.h
@@ -0,0 +1,19 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+/* mmc_cmds.c */
+int do_read_extcsd(int nargs, char **argv);
+int do_write_extcsd(int nargs, char **argv);