Date:	Thu, 3 Sep 2015 16:08:16 +0100
From:	Jon Hunter <jonathanh@...dia.com>
To:	Olof Johansson <olof@...om.net>
CC:	Ulf Hansson <ulf.hansson@...aro.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Grant Grundler <grundler@...gle.com>,
	"Olof Johansson" <olofj@...omium.org>,
	Seshagiri Holi <sholi@...dia.com>
Subject: Re: [RFC PATCH] mmc: block: Add new ioctl to send combo commands

Hi Olof,

On 02/09/15 19:28, Olof Johansson wrote:
> Hi,
> 
> On Wed, Sep 2, 2015 at 7:21 AM, Jon Hunter <jonathanh@...dia.com> wrote:
>> From: Seshagiri Holi <sholi@...dia.com>
>>
>> Certain eMMC devices allow vendor specific device information to be read
>> via a sequence of vendor commands. These vendor commands must be issued
>> in sequence and an atomic fashion. One way to support this would be to
>> add an ioctl function for sending a sequence of commands to the device
>> atomically as proposed here. These combo commands are simple array of
>> the existing mmc_ioc_cmd structure.
> 
> This seems reasonable to me, being able to do a sequence of
> back-to-back operations without system read/writes slipping through.
> 
>> diff --git a/include/uapi/linux/mmc/ioctl.h b/include/uapi/linux/mmc/ioctl.h
>> index 1f5e68923929..5943e51f22b3 100644
>> --- a/include/uapi/linux/mmc/ioctl.h
>> +++ b/include/uapi/linux/mmc/ioctl.h
>> @@ -45,8 +45,23 @@ struct mmc_ioc_cmd {
>>  };
>>  #define mmc_ioc_cmd_set_data(ic, ptr) ic.data_ptr = (__u64)(unsigned long) ptr
>>
>> -#define MMC_IOC_CMD _IOWR(MMC_BLOCK_MAJOR, 0, struct mmc_ioc_cmd)
>> +/**
>> + * struct mmc_ioc_combo_cmd - combo command information
>> + * @num_of_cmds: number of commands to send
>> + * @mmc_ioc_cmd_list: pointer to list of commands
>> + */
>> +struct mmc_ioc_combo_cmd {
>> +       uint8_t num_of_cmds;
>> +       struct mmc_ioc_cmd *mmc_ioc_cmd_list;
>> +};
> 
> The size of this struct will depend on the pointer size of userspace.
> 
> It might be better to use a u64 for the pointer instead. Otherwise
> you'd need a compat ioctl wrapper to copy a 32-bit pointer over on a
> 64-bit kernel.

Oh, good point. I have made this change today. I have also tested
this now with a hacked version of mmc-utils to send a couple status
commands back-to-back. I have tested on -next with ARM32 and on
ARM64 with an older 3.18 kernel (due to lack of mmc support in the
mainline for my ARM64 board) and seems to be working fine. Here is
an updated version ...

Jon

>From fe5849a0d91ebbcfd092c74696f3fa7d7de3a156 Mon Sep 17 00:00:00 2001
From: Seshagiri Holi <sholi@...dia.com>
Date: Mon, 4 Nov 2013 17:27:43 +0530
Subject: [PATCH] mmc: block: Add new ioctl to send combo commands

Certain eMMC devices allow vendor specific device information to be read
via a sequence of vendor commands. These vendor commands must be issued
in sequence and an atomic fashion. One way to support this would be to
add an ioctl function for sending a sequence of commands to the device
atomically as proposed here. These combo commands are simple array of
the existing mmc_ioc_cmd structure.

Signed-off-by: Seshagiri Holi <sholi@...dia.com>
[ jonathanh@...dia.com: Rebased on linux-next from v3.18. Changed
  userspace pointer type for combo command to be a u64. Updated
  commit message ]
Signed-off-by: Jon Hunter <jonathanh@...dia.com>
---
 drivers/mmc/card/block.c       | 199 ++++++++++++++++++++++++++++++++---------
 include/uapi/linux/mmc/ioctl.h |  17 +++-
 2 files changed, 171 insertions(+), 45 deletions(-)

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index c742cfd7674e..0423d95ea020 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -387,6 +387,22 @@ out:
 	return ERR_PTR(err);
 }
 
+static int mmc_blk_ioctl_copy_to_user(struct mmc_ioc_cmd __user *ic_ptr,
+				      struct mmc_blk_ioc_data *idata)
+{
+	if (copy_to_user(&(ic_ptr->response), idata->ic.response,
+			 sizeof(idata->ic.response)))
+		return -EFAULT;
+
+	if (!idata->ic.write_flag) {
+		if (copy_to_user((void __user *)(unsigned long)idata->ic.data_ptr,
+				 idata->buf, idata->buf_bytes))
+			return -EFAULT;
+	}
+
+	return 0;
+}
+
 static int ioctl_rpmb_card_status_poll(struct mmc_card *card, u32 *status,
 				       u32 retries_max)
 {
@@ -447,12 +463,9 @@ out:
 	return err;
 }
 
-static int mmc_blk_ioctl_cmd(struct block_device *bdev,
-	struct mmc_ioc_cmd __user *ic_ptr)
+static int __mmc_blk_ioctl_cmd(struct mmc_card *card, struct mmc_blk_data *md,
+			       struct mmc_blk_ioc_data *idata)
 {
-	struct mmc_blk_ioc_data *idata;
-	struct mmc_blk_data *md;
-	struct mmc_card *card;
 	struct mmc_command cmd = {0};
 	struct mmc_data data = {0};
 	struct mmc_request mrq = {NULL};
@@ -461,33 +474,12 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
 	int is_rpmb = false;
 	u32 status = 0;
 
-	/*
-	 * The caller must have CAP_SYS_RAWIO, and must be calling this on the
-	 * whole block device, not on a partition.  This prevents overspray
-	 * between sibling partitions.
-	 */
-	if ((!capable(CAP_SYS_RAWIO)) || (bdev != bdev->bd_contains))
-		return -EPERM;
-
-	idata = mmc_blk_ioctl_copy_from_user(ic_ptr);
-	if (IS_ERR(idata))
-		return PTR_ERR(idata);
-
-	md = mmc_blk_get(bdev->bd_disk);
-	if (!md) {
-		err = -EINVAL;
-		goto cmd_err;
-	}
+	if (!card || !md || !idata)
+		return -EINVAL;
 
 	if (md->area_type & MMC_BLK_DATA_AREA_RPMB)
 		is_rpmb = true;
 
-	card = md->queue.card;
-	if (IS_ERR(card)) {
-		err = PTR_ERR(card);
-		goto cmd_done;
-	}
-
 	cmd.opcode = idata->ic.opcode;
 	cmd.arg = idata->ic.arg;
 	cmd.flags = idata->ic.flags;
@@ -582,18 +574,7 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
 	if (idata->ic.postsleep_min_us)
 		usleep_range(idata->ic.postsleep_min_us, idata->ic.postsleep_max_us);
 
-	if (copy_to_user(&(ic_ptr->response), cmd.resp, sizeof(cmd.resp))) {
-		err = -EFAULT;
-		goto cmd_rel_host;
-	}
-
-	if (!idata->ic.write_flag) {
-		if (copy_to_user((void __user *)(unsigned long) idata->ic.data_ptr,
-						idata->buf, idata->buf_bytes)) {
-			err = -EFAULT;
-			goto cmd_rel_host;
-		}
-	}
+	memcpy(&(idata->ic.response), cmd.resp, sizeof(cmd.resp));
 
 	if (is_rpmb) {
 		/*
@@ -609,6 +590,48 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
 
 cmd_rel_host:
 	mmc_put_card(card);
+	return err;
+}
+
+static int mmc_blk_ioctl_cmd(struct block_device *bdev,
+			struct mmc_ioc_cmd __user *ic_ptr)
+{
+	struct mmc_blk_ioc_data *idata;
+	struct mmc_blk_data *md;
+	struct mmc_card *card;
+	int err;
+
+	/*
+	 * The caller must have CAP_SYS_RAWIO, and must be calling this on the
+	 * whole block device, not on a partition.  This prevents overspray
+	 * between sibling partitions.
+	 */
+	if ((!capable(CAP_SYS_RAWIO)) || (bdev != bdev->bd_contains))
+		return -EPERM;
+
+	idata = mmc_blk_ioctl_copy_from_user(ic_ptr);
+	if (IS_ERR(idata))
+		return PTR_ERR(idata);
+
+	md = mmc_blk_get(bdev->bd_disk);
+	if (!md) {
+		err = -EINVAL;
+		goto cmd_err;
+	}
+
+	card = md->queue.card;
+	if (IS_ERR(card)) {
+		err = PTR_ERR(card);
+		goto cmd_done;
+	}
+
+	mmc_claim_host(card->host);
+
+	err = __mmc_blk_ioctl_cmd(card, md, idata);
+
+	mmc_release_host(card->host);
+
+	err = mmc_blk_ioctl_copy_to_user(ic_ptr, idata);
 
 cmd_done:
 	mmc_blk_put(md);
@@ -618,13 +641,101 @@ cmd_err:
 	return err;
 }
 
+static int mmc_blk_ioctl_combo_cmd(struct block_device *bdev,
+				   struct mmc_ioc_combo_cmd __user *user)
+{
+	struct mmc_ioc_combo_cmd mcci = {0};
+	struct mmc_blk_ioc_data **ioc_data = NULL;
+	struct mmc_ioc_cmd __user *usr_ptr;
+	struct mmc_card *card;
+	struct mmc_blk_data *md;
+	int i, err = -EFAULT;
+	u8 n_cmds = 0;
+
+	/*
+	 * The caller must have CAP_SYS_RAWIO, and must be calling this on the
+	 * whole block device, not on a partition.  This prevents overspray
+	 * between sibling partitions.
+	 */
+	if ((!capable(CAP_SYS_RAWIO)) || (bdev != bdev->bd_contains))
+		return -EPERM;
+
+	if (copy_from_user(&mcci, user, sizeof(struct mmc_ioc_combo_cmd)))
+		return -EFAULT;
+
+	if (!mcci.num_of_cmds) {
+		err = -EINVAL;
+		goto cmd_err;
+	}
+
+	ioc_data = kcalloc(mcci.num_of_cmds, sizeof(*ioc_data), GFP_KERNEL);
+	if (!ioc_data) {
+		err = -ENOMEM;
+		goto cmd_err;
+	}
+
+	usr_ptr = (void * __user)(unsigned long)mcci.cmds_ptr;
+	for (n_cmds = 0; n_cmds < mcci.num_of_cmds; n_cmds++) {
+		ioc_data[n_cmds] =
+			mmc_blk_ioctl_copy_from_user(&usr_ptr[n_cmds]);
+		if (IS_ERR(ioc_data[n_cmds])) {
+			err = PTR_ERR(ioc_data[n_cmds]);
+			goto cmd_err;
+		}
+	}
+
+	md = mmc_blk_get(bdev->bd_disk);
+	if (!md)
+		goto cmd_err;
+
+	card = md->queue.card;
+	if (IS_ERR(card)) {
+		err = PTR_ERR(card);
+		goto cmd_done;
+	}
+
+	mmc_claim_host(card->host);
+	for (i = 0; i < n_cmds; i++) {
+		err = __mmc_blk_ioctl_cmd(card, md, ioc_data[i]);
+		if (err) {
+			mmc_release_host(card->host);
+			goto cmd_done;
+		}
+	}
+
+	mmc_release_host(card->host);
+
+	/* copy to user if data and response */
+	for (i = 0; i < n_cmds; i++) {
+		err = mmc_blk_ioctl_copy_to_user(&usr_ptr[i], ioc_data[i]);
+		if (err)
+			break;
+	}
+
+cmd_done:
+	mmc_blk_put(md);
+cmd_err:
+	for (i = 0; i < n_cmds; i++) {
+		kfree(ioc_data[i]->buf);
+		kfree(ioc_data[i]);
+	}
+	kfree(ioc_data);
+	return err;
+}
+
 static int mmc_blk_ioctl(struct block_device *bdev, fmode_t mode,
 	unsigned int cmd, unsigned long arg)
 {
-	int ret = -EINVAL;
-	if (cmd == MMC_IOC_CMD)
-		ret = mmc_blk_ioctl_cmd(bdev, (struct mmc_ioc_cmd __user *)arg);
-	return ret;
+	switch (cmd) {
+	case MMC_IOC_CMD:
+		return mmc_blk_ioctl_cmd(bdev,
+				(struct mmc_ioc_cmd __user *)arg);
+	case MMC_IOC_COMBO_CMD:
+		return mmc_blk_ioctl_combo_cmd(bdev,
+				(struct mmc_ioc_combo_cmd __user *)arg);
+	default:
+		return -EINVAL;
+	}
 }
 
 #ifdef CONFIG_COMPAT
diff --git a/include/uapi/linux/mmc/ioctl.h b/include/uapi/linux/mmc/ioctl.h
index 1f5e68923929..593e665177e2 100644
--- a/include/uapi/linux/mmc/ioctl.h
+++ b/include/uapi/linux/mmc/ioctl.h
@@ -45,8 +45,23 @@ struct mmc_ioc_cmd {
 };
 #define mmc_ioc_cmd_set_data(ic, ptr) ic.data_ptr = (__u64)(unsigned long) ptr
 
-#define MMC_IOC_CMD _IOWR(MMC_BLOCK_MAJOR, 0, struct mmc_ioc_cmd)
+/**
+ * struct mmc_ioc_combo_cmd - combo command information
+ * @cmds_ptr: Address of the location where the list of commands resides
+ * @num_of_cmds: number of commands to send
+ */
+struct mmc_ioc_combo_cmd {
+	__u64 cmds_ptr;
+	uint8_t num_of_cmds;
+};
 
+#define MMC_IOC_CMD _IOWR(MMC_BLOCK_MAJOR, 0, struct mmc_ioc_cmd)
+/*
+ * MMC_COMBO_IOC_CMD: Used to send an array of MMC commands described by
+ *	the structure mmc_ioc_combo_cmd. The MMC driver will issue all
+ *	commands in array in sequence to card.
+ */
+#define MMC_IOC_COMBO_CMD _IOWR(MMC_BLOCK_MAJOR, 1, struct mmc_ioc_combo_cmd)
 /*
  * Since this ioctl is only meant to enhance (and not replace) normal access
  * to the mmc bus device, an upper data transfer limit of MMC_IOC_MAX_BYTES
-- 
2.1.4

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