[PATCH 4/4] mci: add MBR write and read function to block devices

[Michael Grzeschik]

With this patch it is possible to write an mbr partition table to the
mci block device. By setting the device property "dos_partitions" of the
mmc device node, it is possible to write back the new partition layout
in the common cmdlinepart notation. The property can also be read back.

Signed-off-by: Michael Grzeschik <m.grzeschik at pengutronix.de>
---
 drivers/mci/mci-core.c | 122 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)

diff --git a/drivers/mci/mci-core.c b/drivers/mci/mci-core.c
index 4e176f7..c0013a1 100644
--- a/drivers/mci/mci-core.c
+++ b/drivers/mci/mci-core.c
@@ -33,9 +33,11 @@
 #include <asm-generic/div64.h>
 #include <asm/byteorder.h>
 #include <block.h>
+#include <fcntl.h>
 #include <disks.h>
 #include <of.h>
 #include <linux/err.h>
+#include <cmdlinepart.h>
 
 #define MAX_BUFFER_NUMBER 0xffffffff
 
@@ -1527,6 +1529,122 @@ static void mci_info(struct device_d *dev)
 		extract_mtd_year(mci));
 }
 
+static char *print_size(uint64_t s)
+{
+	if (!(s & ((1 << 20) - 1)))
+		return basprintf("%lldM", s >> 20);
+	if (!(s & ((1 << 10) - 1)))
+		return basprintf("%lldk", s >> 10);
+	return basprintf("0x%lld", s);
+}
+
+static int print_part(char *buf, int bufsize, struct cdev *cdev, int is_last)
+{
+	char *size = print_size(cdev->size);
+	int ret;
+
+	if (!size) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = snprintf(buf, bufsize, "%s(%s)%s", size,
+			cdev->partname,
+			is_last ? "" : ",");
+out:
+	free(size);
+
+	return ret;
+}
+
+static int print_parts(char *buf, int bufsize, struct mci *mci)
+{
+	struct cdev *cdev, *ct;
+	int ret = 0;
+
+	list_for_each_entry_safe(cdev, ct, &mci->dev.cdevs, devices_list) {
+		if ((cdev->flags & DEVFS_IS_PARTITION) &&
+			(cdev->flags & DEVFS_PARTITION_IN_PT)) {
+			int now;
+			int is_last = 0;
+			struct list_head *nh = (cdev)->devices_list.next;
+			struct cdev *next = container_of(nh, typeof(*(cdev)), devices_list);
+
+			if (list_is_last(&cdev->devices_list, &mci->dev.cdevs) ||
+				!(next->flags & DEVFS_PARTITION_IN_PT))
+				is_last = 1;
+
+			now = print_part(buf, bufsize, cdev, is_last);
+			if (now < 0)
+				return now;
+
+			if (buf && bufsize) {
+				buf += now;
+				bufsize -= now;
+			}
+			ret += now;
+		}
+	}
+
+	return ret;
+}
+
+static const char *mci_partition_get(struct device_d *dev, struct param_d *p)
+{
+	struct mci *mci = container_of(dev, struct mci, dev);
+	int len = 0;
+
+	free(p->value);
+
+	len = print_parts(NULL, 0, mci);
+	p->value = xzalloc(len + 1);
+	print_parts(p->value, len + 1, mci);
+
+	return p->value;
+}
+
+#ifdef CONFIG_BLOCK_WRITE
+static int mci_partition_set(struct device_d *dev, struct param_d *p, const char *val)
+{
+	struct mci *mci = container_of(dev, struct mci, dev);
+	struct cdev *cdev, *ct;
+	int ret;
+
+	if (!val)
+		return -EINVAL;
+
+	/* remove all partition cdevs with DEVFS_IS_PARTITION set */
+	list_for_each_entry_safe(cdev, ct, &mci->dev.cdevs, devices_list) {
+		if ((cdev->flags & DEVFS_IS_PARTITION) &&
+			(cdev->flags & DEVFS_PARTITION_IN_PT))
+			ret = devfs_del_partition(cdev->name);
+			if (ret)
+				return ret;
+	}
+
+	/* read back the prepared partition layot from dos_partitions param */
+	ret = cmdlinepart_do_parse(mci->cdevname, val, mci->capacity,
+			CMDLINEPART_ADD_DEVNAME | CMDLINEPART_ADD_TO_PT);
+	if (ret)
+		return ret;
+
+	/* write the MBR partition layout based on cdevs with DEVFS_IS_PARTITION set  */
+	for (int i = 0; i < mci->nr_parts; i++) {
+		struct mci_part *part = &mci->part[i];
+		if (part->area_type == MMC_BLK_DATA_AREA_MAIN) {
+			ret = write_dos_partition_table(&part->blk,
+							&mci->dev.cdevs);
+			if (ret != 0) {
+				dev_warn(&mci->dev, "Could not write partition table\n");
+				return ret;
+			}
+		}
+	}
+
+	return ret;
+}
+#endif
+
 /**
  * Check if the MCI card is already probed
  * @param mci MCI device instance
@@ -1786,6 +1904,10 @@ int mci_register(struct mci_host *host)
 	mci->param_probe = dev_add_param_bool(&mci->dev, "probe",
 			mci_set_probe, NULL, &mci->probe, mci);
 
+#ifdef CONFIG_BLOCK_WRITE
+	dev_add_param(&mci->dev, "dos_partitions", mci_partition_set, mci_partition_get, 0);
+#endif
+
 	if (IS_ERR(mci->param_probe) && PTR_ERR(mci->param_probe) != -ENOSYS) {
 		ret = PTR_ERR(mci->param_probe);
 		dev_dbg(&mci->dev, "Failed to add 'probe' parameter to the MCI device\n");
-- 
2.9.3