mmc: debugfs: Move block debugfs into block module

If we don't have the block layer enabled, we do not present card
status and extcsd in the debugfs.

Debugfs is not ABI, and maintaining files of no relevance for
non-block devices comes at a high maintenance cost if we shall
support it with the block layer compiled out.

The debugfs entries suffer from all the same starvation
issues as the other userspace things, under e.g. a heavy
dd operation.

The expected number of debugfs users utilizing these two
debugfs files is already low as there is an ioctl() to get the
same information using the mmc-tools, and of these few users
the expected number of people using it on SDIO or combo cards
are expected to be zero.

It is therefore logical to move this over to the block layer
when it is enabled, using the new custom requests and issue
it using the block request queue.

On the other hand it moves some debugfs code from debugfs.c
and into block.c.

Tested during heavy dd load by cat:in the status file.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/block.c

@@ -36,6 +36,7 @@
 #include <linux/compat.h>
 #include <linux/pm_runtime.h>
 #include <linux/idr.h>
+#include <linux/debugfs.h>
 
 #include <linux/mmc/ioctl.h>
 #include <linux/mmc/card.h>
@@ -1177,6 +1178,8 @@ static void mmc_blk_issue_drv_op(struct mmc_queue *mq, struct request *req)
 	struct mmc_card *card = mq->card;
 	struct mmc_blk_data *md = mq->blkdata;
 	struct mmc_blk_ioc_data **idata;
+	u8 **ext_csd;
+	u32 status;
 	int ret;
 	int i;
 
@@ -1206,6 +1209,15 @@ static void mmc_blk_issue_drv_op(struct mmc_queue *mq, struct request *req)
 			card->ext_csd.boot_ro_lock |=
 				EXT_CSD_BOOT_WP_B_PWR_WP_EN;
 		break;
+	case MMC_DRV_OP_GET_CARD_STATUS:
+		ret = mmc_send_status(card, &status);
+		if (!ret)
+			ret = status;
+		break;
+	case MMC_DRV_OP_GET_EXT_CSD:
+		ext_csd = mq_rq->drv_op_data;
+		ret = mmc_get_ext_csd(card, ext_csd);
+		break;
 	default:
 		pr_err("%s: unknown driver specific operation\n",
 		       md->disk->disk_name);
@@ -2283,6 +2295,134 @@ force_ro_fail:
 	return ret;
 }
 
+#ifdef CONFIG_DEBUG_FS
+
+static int mmc_dbg_card_status_get(void *data, u64 *val)
+{
+	struct mmc_card *card = data;
+	struct mmc_blk_data *md = dev_get_drvdata(&card->dev);
+	struct mmc_queue *mq = &md->queue;
+	struct request *req;
+	int ret;
+
+	/* Ask the block layer about the card status */
+	req = blk_get_request(mq->queue, REQ_OP_DRV_IN, __GFP_RECLAIM);
+	req_to_mmc_queue_req(req)->drv_op = MMC_DRV_OP_GET_CARD_STATUS;
+	blk_execute_rq(mq->queue, NULL, req, 0);
+	ret = req_to_mmc_queue_req(req)->drv_op_result;
+	if (ret >= 0) {
+		*val = ret;
+		ret = 0;
+	}
+
+	return ret;
+}
+DEFINE_SIMPLE_ATTRIBUTE(mmc_dbg_card_status_fops, mmc_dbg_card_status_get,
+		NULL, "%08llx\n");
+
+/* That is two digits * 512 + 1 for newline */
+#define EXT_CSD_STR_LEN 1025
+
+static int mmc_ext_csd_open(struct inode *inode, struct file *filp)
+{
+	struct mmc_card *card = inode->i_private;
+	struct mmc_blk_data *md = dev_get_drvdata(&card->dev);
+	struct mmc_queue *mq = &md->queue;
+	struct request *req;
+	char *buf;
+	ssize_t n = 0;
+	u8 *ext_csd;
+	int err, i;
+
+	buf = kmalloc(EXT_CSD_STR_LEN + 1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	/* Ask the block layer for the EXT CSD */
+	req = blk_get_request(mq->queue, REQ_OP_DRV_IN, __GFP_RECLAIM);
+	req_to_mmc_queue_req(req)->drv_op = MMC_DRV_OP_GET_EXT_CSD;
+	req_to_mmc_queue_req(req)->drv_op_data = &ext_csd;
+	blk_execute_rq(mq->queue, NULL, req, 0);
+	err = req_to_mmc_queue_req(req)->drv_op_result;
+	if (err) {
+		pr_err("FAILED %d\n", err);
+		goto out_free;
+	}
+
+	for (i = 0; i < 512; i++)
+		n += sprintf(buf + n, "%02x", ext_csd[i]);
+	n += sprintf(buf + n, "\n");
+
+	if (n != EXT_CSD_STR_LEN) {
+		err = -EINVAL;
+		goto out_free;
+	}
+
+	filp->private_data = buf;
+	kfree(ext_csd);
+	return 0;
+
+out_free:
+	kfree(buf);
+	return err;
+}
+
+static ssize_t mmc_ext_csd_read(struct file *filp, char __user *ubuf,
+				size_t cnt, loff_t *ppos)
+{
+	char *buf = filp->private_data;
+
+	return simple_read_from_buffer(ubuf, cnt, ppos,
+				       buf, EXT_CSD_STR_LEN);
+}
+
+static int mmc_ext_csd_release(struct inode *inode, struct file *file)
+{
+	kfree(file->private_data);
+	return 0;
+}
+
+static const struct file_operations mmc_dbg_ext_csd_fops = {
+	.open		= mmc_ext_csd_open,
+	.read		= mmc_ext_csd_read,
+	.release	= mmc_ext_csd_release,
+	.llseek		= default_llseek,
+};
+
+static int mmc_blk_add_debugfs(struct mmc_card *card)
+{
+	struct dentry *root;
+
+	if (!card->debugfs_root)
+		return 0;
+
+	root = card->debugfs_root;
+
+	if (mmc_card_mmc(card) || mmc_card_sd(card)) {
+		if (!debugfs_create_file("status", S_IRUSR, root, card,
+					 &mmc_dbg_card_status_fops))
+			return -EIO;
+	}
+
+	if (mmc_card_mmc(card)) {
+		if (!debugfs_create_file("ext_csd", S_IRUSR, root, card,
+					 &mmc_dbg_ext_csd_fops))
+			return -EIO;
+	}
+
+	return 0;
+}
+
+
+#else
+
+static int mmc_blk_add_debugfs(struct mmc_card *card)
+{
+	return 0;
+}
+
+#endif /* CONFIG_DEBUG_FS */
+
 static int mmc_blk_probe(struct mmc_card *card)
 {
 	struct mmc_blk_data *md, *part_md;
@@ -2319,6 +2459,9 @@ static int mmc_blk_probe(struct mmc_card *card)
 			goto out;
 	}
 
+	/* Add two debugfs entries */
+	mmc_blk_add_debugfs(card);
+
 	pm_runtime_set_autosuspend_delay(&card->dev, 3000);
 	pm_runtime_use_autosuspend(&card->dev);
 

drivers/mmc/core/debugfs.c

@@ -281,85 +281,6 @@ void mmc_remove_host_debugfs(struct mmc_host *host)
 	debugfs_remove_recursive(host->debugfs_root);
 }
 
-static int mmc_dbg_card_status_get(void *data, u64 *val)
-{
-	struct mmc_card	*card = data;
-	u32		status;
-	int		ret;
-
-	mmc_get_card(card);
-
-	ret = mmc_send_status(data, &status);
-	if (!ret)
-		*val = status;
-
-	mmc_put_card(card);
-
-	return ret;
-}
-DEFINE_SIMPLE_ATTRIBUTE(mmc_dbg_card_status_fops, mmc_dbg_card_status_get,
-		NULL, "%08llx\n");
-
-#define EXT_CSD_STR_LEN 1025
-
-static int mmc_ext_csd_open(struct inode *inode, struct file *filp)
-{
-	struct mmc_card *card = inode->i_private;
-	char *buf;
-	ssize_t n = 0;
-	u8 *ext_csd;
-	int err, i;
-
-	buf = kmalloc(EXT_CSD_STR_LEN + 1, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-
-	mmc_get_card(card);
-	err = mmc_get_ext_csd(card, &ext_csd);
-	mmc_put_card(card);
-	if (err)
-		goto out_free;
-
-	for (i = 0; i < 512; i++)
-		n += sprintf(buf + n, "%02x", ext_csd[i]);
-	n += sprintf(buf + n, "\n");
-
-	if (n != EXT_CSD_STR_LEN) {
-		err = -EINVAL;
-		goto out_free;
-	}
-
-	filp->private_data = buf;
-	kfree(ext_csd);
-	return 0;
-
-out_free:
-	kfree(buf);
-	return err;
-}
-
-static ssize_t mmc_ext_csd_read(struct file *filp, char __user *ubuf,
-				size_t cnt, loff_t *ppos)
-{
-	char *buf = filp->private_data;
-
-	return simple_read_from_buffer(ubuf, cnt, ppos,
-				       buf, EXT_CSD_STR_LEN);
-}
-
-static int mmc_ext_csd_release(struct inode *inode, struct file *file)
-{
-	kfree(file->private_data);
-	return 0;
-}
-
-static const struct file_operations mmc_dbg_ext_csd_fops = {
-	.open		= mmc_ext_csd_open,
-	.read		= mmc_ext_csd_read,
-	.release	= mmc_ext_csd_release,
-	.llseek		= default_llseek,
-};
-
 void mmc_add_card_debugfs(struct mmc_card *card)
 {
 	struct mmc_host	*host = card->host;
@@ -382,16 +303,6 @@ void mmc_add_card_debugfs(struct mmc_card *card)
 	if (!debugfs_create_x32("state", S_IRUSR, root, &card->state))
 		goto err;
 
-	if (mmc_card_mmc(card) || mmc_card_sd(card))
-		if (!debugfs_create_file("status", S_IRUSR, root, card,
-					&mmc_dbg_card_status_fops))
-			goto err;
-
-	if (mmc_card_mmc(card))
-		if (!debugfs_create_file("ext_csd", S_IRUSR, root, card,
-					&mmc_dbg_ext_csd_fops))
-			goto err;
-
 	return;
 
 err:

drivers/mmc/core/queue.h

@@ -36,10 +36,14 @@ struct mmc_blk_request {
  * enum mmc_drv_op - enumerates the operations in the mmc_queue_req
  * @MMC_DRV_OP_IOCTL: ioctl operation
  * @MMC_DRV_OP_BOOT_WP: write protect boot partitions
+ * @MMC_DRV_OP_GET_CARD_STATUS: get card status
+ * @MMC_DRV_OP_GET_EXT_CSD: get the EXT CSD from an eMMC card
  */
 enum mmc_drv_op {
 	MMC_DRV_OP_IOCTL,
 	MMC_DRV_OP_BOOT_WP,
+	MMC_DRV_OP_GET_CARD_STATUS,
+	MMC_DRV_OP_GET_EXT_CSD,
 };
 
 struct mmc_queue_req {