Add extcsd write-protect read/write code

This was posted to linux-mmc@ by Johan Rudholm.
Signed-off-by: Chris Ball <cjb@laptop.org>

Makefile

 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
 

mmc.h

+/*
+ * 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)

mmc_cmds.c

+/*
+ * 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;
+}

mmc_cmds.h

+/*
+ * 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);