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Commit df032bf2 authored by Avri Altman's avatar Avri Altman Committed by Martin K. Petersen
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scsi: ufs: Add a bsg endpoint that supports UPIUs 



For now, just provide an API to allocate and remove ufs-bsg node. We
will use this framework to manage ufs devices by sending UPIU
transactions.

For the time being, implements an empty bsg_request() - will add some
more functionality in coming patches.

Nonetheless, we reveal here the protocol we are planning to use: UFS
Transport Protocol Transactions. UFS transactions consist of packets
called UFS Protocol Information Units (UPIU).

There are UPIU’s defined for UFS SCSI commands, responses, data in and
data out, task management, utility functions, vendor functions,
transaction synchronization and control, and more.

By using UPIUs, we get access to the most fine-grained internals of this
protocol, and able to communicate with the device in ways, that are
sometimes beyond the capacity of the ufs driver.

Moreover and as a result, our core structure - ufs_bsg_node has a pretty
lean structure: using upiu transactions that contains the outmost
detailed info, so we don't really need complex constructs to support it.

Signed-off-by: default avatarAvri Altman <avri.altman@wdc.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarBart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent a851b2bd

Documentation/scsi/ufs.txt

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@@ -128,6 +128,26 @@ The current UFSHCD implementation supports following functionality, 
In this version of UFSHCD Query requests and power management

functionality are not implemented.



4. BSG Support

------------------



This transport driver supports exchanging UFS protocol information units

(UPIUs) with a UFS device. Typically, user space will allocate

struct ufs_bsg_request and struct ufs_bsg_reply (see ufs_bsg.h) as

request_upiu and reply_upiu respectively.  Filling those UPIUs should

be done in accordance with JEDEC spec UFS2.1 paragraph 10.7.

*Caveat emptor*: The driver makes no further input validations and sends the

UPIU to the device as it is.  Open the bsg device in /dev/ufs-bsg and

send SG_IO with the applicable sg_io_v4:



	io_hdr_v4.guard = 'Q';

	io_hdr_v4.protocol = BSG_PROTOCOL_SCSI;

	io_hdr_v4.subprotocol = BSG_SUB_PROTOCOL_SCSI_TRANSPORT;

	io_hdr_v4.response = (__u64)reply_upiu;

	io_hdr_v4.max_response_len = reply_len;

	io_hdr_v4.request_len = request_len;

	io_hdr_v4.request = (__u64)request_upiu;



UFS Specifications can be found at,

UFS - http://www.jedec.org/sites/default/files/docs/JESD220.pdf

UFSHCI - http://www.jedec.org/sites/default/files/docs/JESD223.pdf

drivers/scsi/ufs/Kconfig

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@@ -109,3 +109,22 @@ config SCSI_UFS_HISI 


	  Select this if you have UFS controller on Hisilicon chipset.

	  If unsure, say N.



config SCSI_UFS_BSG

	bool "Universal Flash Storage BSG device node"

	depends on SCSI_UFSHCD

	select BLK_DEV_BSGLIB

	help

	  Universal Flash Storage (UFS) is SCSI transport specification for

	  accessing flash storage on digital cameras, mobile phones and

	  consumer electronic devices.

	  A UFS controller communicates with a UFS device by exchanging

	  UFS Protocol Information Units (UPIUs).

	  UPIUs can not only be used as a transport layer for the SCSI protocol

	  but are also used by the UFS native command set.

	  This transport driver supports exchanging UFS protocol information units

	  with a UFS device. See also the ufshcd driver, which is a SCSI driver

	  that supports UFS devices.



	  Select this if you need a bsg device node for your UFS controller.

	  If unsure, say N.

drivers/scsi/ufs/Makefile

+2 −1
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@@ -4,7 +4,8 @@ obj-$(CONFIG_SCSI_UFS_DWC_TC_PCI) += tc-dwc-g210-pci.o ufshcd-dwc.o tc-dwc-g210. 
obj-$(CONFIG_SCSI_UFS_DWC_TC_PLATFORM) += tc-dwc-g210-pltfrm.o ufshcd-dwc.o tc-dwc-g210.o

obj-$(CONFIG_SCSI_UFS_QCOM) += ufs-qcom.o

obj-$(CONFIG_SCSI_UFSHCD) += ufshcd-core.o

ufshcd-core-objs := ufshcd.o ufs-sysfs.o

ufshcd-core-y				+= ufshcd.o ufs-sysfs.o

ufshcd-core-$(CONFIG_SCSI_UFS_BSG)	+= ufs_bsg.o

obj-$(CONFIG_SCSI_UFSHCD_PCI) += ufshcd-pci.o

obj-$(CONFIG_SCSI_UFSHCD_PLATFORM) += ufshcd-pltfrm.o

obj-$(CONFIG_SCSI_UFS_HISI) += ufs-hisi.o

drivers/scsi/ufs/ufs_bsg.c

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// SPDX-License-Identifier: GPL-2.0

/*

 * bsg endpoint that supports UPIUs

 *

 * Copyright (C) 2018 Western Digital Corporation

 */

#include "ufs_bsg.h"





static int ufs_bsg_request(struct bsg_job *job)

{

	struct ufs_bsg_request *bsg_request = job->request;

	struct ufs_bsg_reply *bsg_reply = job->reply;

	int ret = -ENOTSUPP;



	bsg_reply->reply_payload_rcv_len = 0;



	/* Do Nothing for now */

	dev_err(job->dev, "unsupported message_code 0x%x\n",

		bsg_request->msgcode);



	bsg_reply->result = ret;

	job->reply_len = sizeof(struct ufs_bsg_reply) +

			 bsg_reply->reply_payload_rcv_len;



	bsg_job_done(job, ret, bsg_reply->reply_payload_rcv_len);



	return ret;

}



/**

 * ufs_bsg_remove - detach and remove the added ufs-bsg node

 *

 * Should be called when unloading the driver.

 */

void ufs_bsg_remove(struct ufs_hba *hba)

{

	struct device *bsg_dev = &hba->bsg_dev;



	if (!hba->bsg_queue)

		return;



	bsg_unregister_queue(hba->bsg_queue);



	device_del(bsg_dev);

	put_device(bsg_dev);

}



static inline void ufs_bsg_node_release(struct device *dev)

{

	put_device(dev->parent);

}



/**

 * ufs_bsg_probe - Add ufs bsg device node

 * @hba: per adapter object

 *

 * Called during initial loading of the driver, and before scsi_scan_host.

 */

int ufs_bsg_probe(struct ufs_hba *hba)

{

	struct device *bsg_dev = &hba->bsg_dev;

	struct Scsi_Host *shost = hba->host;

	struct device *parent = &shost->shost_gendev;

	struct request_queue *q;

	int ret;



	device_initialize(bsg_dev);



	bsg_dev->parent = get_device(parent);

	bsg_dev->release = ufs_bsg_node_release;



	dev_set_name(bsg_dev, "ufs-bsg");



	ret = device_add(bsg_dev);

	if (ret)

		goto out;



	q = bsg_setup_queue(bsg_dev, dev_name(bsg_dev), ufs_bsg_request, 0);

	if (IS_ERR(q)) {

		ret = PTR_ERR(q);

		goto out;

	}



	hba->bsg_queue = q;



	return 0;



out:

	dev_err(bsg_dev, "fail to initialize a bsg dev %d\n", shost->host_no);

	put_device(bsg_dev);

	return ret;

}

drivers/scsi/ufs/ufs_bsg.h

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/* SPDX-License-Identifier: GPL-2.0 */

/*

 * Copyright (C) 2018 Western Digital Corporation

 */

#ifndef UFS_BSG_H

#define UFS_BSG_H



#include <linux/bsg-lib.h>

#include <scsi/scsi.h>

#include <scsi/scsi_host.h>



#include "ufshcd.h"

#include "ufs.h"



#ifdef CONFIG_SCSI_UFS_BSG

void ufs_bsg_remove(struct ufs_hba *hba);

int ufs_bsg_probe(struct ufs_hba *hba);

#else

static inline void ufs_bsg_remove(struct ufs_hba *hba) {}

static inline int ufs_bsg_probe(struct ufs_hba *hba) {return 0; }

#endif



#endif /* UFS_BSG_H */