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Subject: Re: [PATCH V12 2/2] scsi: ufs: Add configfs support for UFS
 provisioning
To:     Sayali Lokhande <sayalil@codeaurora.org>, subhashj@codeaurora.org,
        cang@codeaurora.org, vivek.gautam@codeaurora.org,
        rnayak@codeaurora.org, vinholikatti@gmail.com,
        jejb@linux.vnet.ibm.com, martin.petersen@oracle.com,
        asutoshd@codeaurora.org, evgreen@chromium.org,
        riteshh@codeaurora.org
Cc:     stummala@codeaurora.org, jlbec@evilplan.org,
        linux-scsi@vger.kernel.org,
        open list <linux-kernel@vger.kernel.org>
References: <1535626003-4966-1-git-send-email-sayalil@codeaurora.org>
 <1535626003-4966-3-git-send-email-sayalil@codeaurora.org>
From:   Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
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Message-ID: <b1a8913e-5baf-0bf1-96a4-c502c5ba733f@intel.com>
Date:   Wed, 12 Sep 2018 16:14:14 +0300
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On 30/08/18 13:46, Sayali Lokhande wrote:
> This patch adds configfs support to provision UFS device at
> runtime. This feature can be primarily useful in factory or
> assembly line as some devices may be required to be configured
> multiple times during initial system development phase.
> Configuration Descriptors can be written multiple times until
> bConfigDescrLock attribute is zero.
> 
> Configuration descriptor buffer consists of Device and Unit
> descriptor configurable parameters which are parsed from vendor
> specific provisioning file and then passed via configfs node at
> runtime to provision ufs device.
> CONFIG_CONFIGFS_FS and CONFIG_UFS_PROVISION needs to be enabled
> for using this feature.
> 
> Usage:
> 1) To read current configuration descriptor with index X
>    (where index X can be 0/1/2/3) :
>    cat /config/XXXX.ufshc/ufs_config_desc_X

Device name could be nearly anything, not necessarily in the form
XXXX.ufshc, so maybe make this :

    cat /config/<device name>/ufs_config_desc_X

> 
> 2) To write configuration descriptor with index X :
>    echo <config_desc_buf> > /config/XXXX.ufshc/ufs_config_desc_X

Ditto

> 
> Signed-off-by: Sayali Lokhande <sayalil@codeaurora.org>
> ---
>  Documentation/ABI/testing/configfs-driver-ufs |  12 ++
>  drivers/scsi/ufs/Kconfig                      |  10 ++
>  drivers/scsi/ufs/Makefile                     |   1 +
>  drivers/scsi/ufs/ufs-configfs.c               | 232 ++++++++++++++++++++++++++
>  drivers/scsi/ufs/ufshcd.c                     |   3 +-
>  drivers/scsi/ufs/ufshcd.h                     |  17 ++
>  6 files changed, 274 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/ABI/testing/configfs-driver-ufs
>  create mode 100644 drivers/scsi/ufs/ufs-configfs.c
> 
> diff --git a/Documentation/ABI/testing/configfs-driver-ufs b/Documentation/ABI/testing/configfs-driver-ufs
> new file mode 100644
> index 0000000..4302d57
> --- /dev/null
> +++ b/Documentation/ABI/testing/configfs-driver-ufs
> @@ -0,0 +1,12 @@
> +What:		/config/*/ufs_config_desc_X
> +Date:		Jun 2018
> +KernelVersion:	4.19

4.20 now

> +Description:
> +		This file shows bytes of the current ufs configuration descriptor
> +		with index X (where X = 0/1/2/3) set in device. This can be used to
> +		provision ufs device if bConfigDescrLock is 0.
> +		For more details, refer 14.1.6.3 Configuration Descriptor and
> +		table 14-12 - Unit Descriptor configurable parameters from specs for
> +		description and format of each configuration descriptor parameter.
> +		Parameters of Configuration descriptor buffer for respective index
> +		needs to be passed as bytes in space separated format.
> diff --git a/drivers/scsi/ufs/Kconfig b/drivers/scsi/ufs/Kconfig
> index e27b4d4..a9a0a58 100644
> --- a/drivers/scsi/ufs/Kconfig
> +++ b/drivers/scsi/ufs/Kconfig
> @@ -100,3 +100,13 @@ config SCSI_UFS_QCOM
>  
>  	  Select this if you have UFS controller on QCOM chipset.
>  	  If unsure, say N.
> +
> +config UFS_PROVISION

Better if this is config SCSI_UFS_PROVISION to avoid mixups with UFS filesystem

> +	tristate "Runtime UFS Provisioning support"

tristate won't work with what you have.  It will have to be bool

> +	depends on SCSI_UFSHCD && CONFIGFS_FS
> +	help
> +	  This enables runtime UFS provisioning support. This can be used
> +	  primarily during assembly line as some devices may be required to
> +	  be configured multiple times during initial development phase.
> +
> +	  If unsure, say N.
> diff --git a/drivers/scsi/ufs/Makefile b/drivers/scsi/ufs/Makefile
> index 918f579..00110ea 100644
> --- a/drivers/scsi/ufs/Makefile
> +++ b/drivers/scsi/ufs/Makefile
> @@ -5,5 +5,6 @@ obj-$(CONFIG_SCSI_UFS_DWC_TC_PLATFORM) += tc-dwc-g210-pltfrm.o ufshcd-dwc.o tc-d
>  obj-$(CONFIG_SCSI_UFS_QCOM) += ufs-qcom.o
>  obj-$(CONFIG_SCSI_UFSHCD) += ufshcd-core.o
>  ufshcd-core-objs := ufshcd.o ufs-sysfs.o
> +obj-$(CONFIG_UFS_PROVISION) += ufs-configfs.o
>  obj-$(CONFIG_SCSI_UFSHCD_PCI) += ufshcd-pci.o
>  obj-$(CONFIG_SCSI_UFSHCD_PLATFORM) += ufshcd-pltfrm.o
> diff --git a/drivers/scsi/ufs/ufs-configfs.c b/drivers/scsi/ufs/ufs-configfs.c
> new file mode 100644
> index 0000000..a2c09c7
> --- /dev/null
> +++ b/drivers/scsi/ufs/ufs-configfs.c
> @@ -0,0 +1,232 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +// Copyright (c) 2018, Linux Foundation.
> +
> +#include <linux/configfs.h>
> +#include <linux/err.h>
> +#include <linux/string.h>
> +
> +#include "ufs.h"
> +#include "ufshcd.h"
> +
> +static inline struct ufs_hba *config_item_to_hba(struct config_item *item)
> +{
> +	struct config_group *group = to_config_group(item);
> +	struct configfs_subsystem *subsys = to_configfs_subsystem(group);
> +	struct ufs_hba *hba = container_of(subsys, struct ufs_hba, subsys);
> +
> +	return hba;
> +}
> +
> +static ssize_t ufs_config_desc_show(struct config_item *item, char *buf,
> +		u8 index)
> +{
> +	struct ufs_hba *hba = config_item_to_hba(item);
> +	u8 *desc_buf = NULL;
> +	int desc_buf_len = hba->desc_size.conf_desc;
> +	int i, ret, curr_len = 0;
> +
> +	desc_buf = kzalloc(desc_buf_len, GFP_KERNEL);
> +	if (!desc_buf)
> +		return -ENOMEM;
> +
> +	ret = ufshcd_query_descriptor_retry(hba, UPIU_QUERY_OPCODE_READ_DESC,
> +		QUERY_DESC_IDN_CONFIGURATION, index, 0,
> +		desc_buf, &desc_buf_len);
> +	if (ret)
> +		goto out;
> +
> +	for (i = 0; i < desc_buf_len; i++)
> +		curr_len += snprintf((buf + curr_len), (PAGE_SIZE - curr_len),
> +				"0x%x ", desc_buf[i]);
> +
> +out:
> +	kfree(desc_buf);
> +	if (ret)
> +		return ret;
> +	return curr_len;

Could be:

	return ret ?: curr_len;

> +}
> +
> +ssize_t ufshcd_desc_configfs_store(struct config_item *item,
> +		const char *buf, size_t count, u8 index)
> +{
> +	char *strbuf;
> +	char *strbuf_copy;
> +	struct ufs_hba *hba = config_item_to_hba(item);
> +	u8 *desc_buf = NULL;
> +	int desc_buf_len = hba->desc_size.conf_desc;
> +	char *token;
> +	int i, ret;
> +	u8 value;
> +	u32 config_desc_lock = 0;
> +
> +	desc_buf = kzalloc(desc_buf_len, GFP_KERNEL);
> +	if (!desc_buf)
> +		return -ENOMEM;
> +
> +	/* reserve one byte for null termination */
> +	strbuf = kmalloc(count + 1, GFP_KERNEL);

buf is null-terminated so just use kstrdup()

> +	if (!strbuf) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +
> +	strbuf_copy = strbuf;
> +	strlcpy(strbuf, buf, count + 1);
> +
> +	/* Just return if bConfigDescrLock is already set */
> +	ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
> +		QUERY_ATTR_IDN_CONF_DESC_LOCK, 0, 0, &config_desc_lock);
> +	if (ret)
> +		goto out;
> +
> +	if (config_desc_lock) {
> +		dev_err(hba->dev, "%s: bConfigDescrLock already set to %u, cannot re-provision device!\n",
> +		__func__, config_desc_lock);

Indenting is not ideal.  Consider some of the suggestions of:
scripts/checkpatch.pl --strict

> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	for (i = 0; i < desc_buf_len; i++) {
> +		token = strsep(&strbuf_copy, " ");
> +		if (!token && i)

What is 'i' doing here?

If the user does not supply enough bytes, the remainder will be overwritten
by 0 which doesn't seem ideal.  It would be better to read desc_buf first.

> +			break;
> +
> +		ret = kstrtou8(token, 0, &value);
> +		if (ret) {
> +			dev_err(hba->dev, "%s: kstrtou8 failed %d %s\n",

User may not understand 'kstrtou8'.  'Invalid value %s writing UFS
configuration descriptor %u' would be better.

> +				__func__, ret, token);
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +		desc_buf[i] = value;
> +	}
> +
> +	/* Write configuration descriptor to provision ufs */
> +	ret = ufshcd_query_descriptor_retry(hba, UPIU_QUERY_OPCODE_WRITE_DESC,
> +		QUERY_DESC_IDN_CONFIGURATION, index, 0,
> +		desc_buf, &desc_buf_len);
> +	if (!ret)
> +		dev_info(hba->dev, "%s: UFS Configuration Descriptor %u written\n",
> +		__func__, index);
> +
> +out:
> +	kfree(strbuf);
> +	kfree(desc_buf);
> +	if (ret)
> +		return ret;
> +	return count;

Could be:

	return ret ?: count;

> +}
> +
> +static ssize_t ufs_config_desc_0_show(struct config_item *item, char *buf)
> +{
> +	return ufs_config_desc_show(item, buf, 0);
> +}
> +
> +static ssize_t ufs_config_desc_0_store(struct config_item *item,
> +		const char *buf, size_t count)
> +{
> +	return ufshcd_desc_configfs_store(item, buf, count, 0);
> +}
> +
> +static ssize_t ufs_config_desc_1_show(struct config_item *item, char *buf)
> +{
> +	return ufs_config_desc_show(item, buf, 1);
> +}
> +
> +static ssize_t ufs_config_desc_1_store(struct config_item *item,
> +		const char *buf, size_t count)
> +{
> +	return ufshcd_desc_configfs_store(item, buf, count, 1);
> +}
> +
> +static ssize_t ufs_config_desc_2_show(struct config_item *item, char *buf)
> +{
> +	return ufs_config_desc_show(item, buf, 2);
> +}
> +
> +static ssize_t ufs_config_desc_2_store(struct config_item *item,
> +		const char *buf, size_t count)
> +{
> +	return ufshcd_desc_configfs_store(item, buf, count, 2);
> +}
> +
> +static ssize_t ufs_config_desc_3_show(struct config_item *item, char *buf)
> +{
> +	return ufs_config_desc_show(item, buf, 3);
> +}
> +
> +static ssize_t ufs_config_desc_3_store(struct config_item *item,
> +		const char *buf, size_t count)
> +{
> +	return ufshcd_desc_configfs_store(item, buf, count, 3);
> +}
> +
> +static struct configfs_attribute ufshcd_attr_provision_0 = {
> +	.ca_name	= "ufs_config_desc_0",
> +	.ca_mode	= 0644,
> +	.ca_owner	= THIS_MODULE,
> +	.show		= ufs_config_desc_0_show,
> +	.store		= ufs_config_desc_0_store,
> +};
> +
> +static struct configfs_attribute ufshcd_attr_provision_1 = {
> +	.ca_name	= "ufs_config_desc_1",
> +	.ca_mode	= 0644,
> +	.ca_owner	= THIS_MODULE,
> +	.show		= ufs_config_desc_1_show,
> +	.store		= ufs_config_desc_1_store,
> +};
> +
> +static struct configfs_attribute ufshcd_attr_provision_2 = {
> +	.ca_name	= "ufs_config_desc_2",
> +	.ca_mode	= 0644,
> +	.ca_owner	= THIS_MODULE,
> +	.show		= ufs_config_desc_2_show,
> +	.store		= ufs_config_desc_2_store,
> +};
> +
> +static struct configfs_attribute ufshcd_attr_provision_3 = {
> +	.ca_name	= "ufs_config_desc_3",
> +	.ca_mode	= 0644,
> +	.ca_owner	= THIS_MODULE,
> +	.show		= ufs_config_desc_3_show,
> +	.store		= ufs_config_desc_3_store,
> +};
> +
> +static struct configfs_attribute *ufshcd_attrs[] = {
> +	&ufshcd_attr_provision_0,
> +	&ufshcd_attr_provision_1,
> +	&ufshcd_attr_provision_2,
> +	&ufshcd_attr_provision_3,
> +	NULL,
> +};
> +
> +static struct config_item_type ufscfg_type = {
> +	.ct_attrs	= ufshcd_attrs,
> +	.ct_owner	= THIS_MODULE,
> +};
> +
> +void ufshcd_configfs_init(struct ufs_hba *hba, const char *name)
> +{
> +	int ret;
> +	struct config_item *cg_item;
> +	struct configfs_subsystem *subsys;
> +
> +	cg_item = &hba->subsys.su_group.cg_item;
> +	sprintf(cg_item->ci_namebuf, "%s", name);
> +	cg_item->ci_type = &ufscfg_type;
> +
> +	subsys = &hba->subsys;
> +	config_group_init(&subsys->su_group);
> +	mutex_init(&subsys->su_mutex);
> +	ret = configfs_register_subsystem(subsys);
> +	if (ret)
> +		pr_err("Error %d while registering subsystem %s\n",
> +		       ret,
> +		       subsys->su_group.cg_item.ci_namebuf);
> +}
> +
> +void ufshcd_configfs_exit(struct ufs_hba *hba)
> +{
> +	configfs_unregister_subsystem(&hba->subsys);
> +}
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index e01cdc0..608e23e 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -7711,6 +7711,7 @@ int ufshcd_shutdown(struct ufs_hba *hba)
>  void ufshcd_remove(struct ufs_hba *hba)
>  {
>  	ufs_sysfs_remove_nodes(hba->dev);
> +	ufshcd_configfs_exit(hba);
>  	scsi_remove_host(hba->host);
>  	/* disable interrupts */
>  	ufshcd_disable_intr(hba, hba->intr_mask);
> @@ -7965,7 +7966,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
>  
>  	async_schedule(ufshcd_async_scan, hba);
>  	ufs_sysfs_add_nodes(hba->dev);
> -
> +	ufshcd_configfs_init(hba, dev_name(hba->dev));
>  	return 0;
>  
>  out_remove_scsi_host:
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index 45013b6..a340ca8 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -37,6 +37,7 @@
>  #ifndef _UFSHCD_H
>  #define _UFSHCD_H
>  
> +#include <linux/configfs.h>
>  #include <linux/module.h>
>  #include <linux/kernel.h>
>  #include <linux/init.h>
> @@ -515,6 +516,9 @@ struct ufs_hba {
>  
>  	struct Scsi_Host *host;
>  	struct device *dev;
> +#ifdef CONFIG_UFS_PROVISION
> +	struct configfs_subsystem subsys;
> +#endif
>  	/*
>  	 * This field is to keep a reference to "scsi_device" corresponding to
>  	 * "UFS device" W-LU.
> @@ -868,6 +872,19 @@ int ufshcd_read_string_desc(struct ufs_hba *hba, int desc_index,
>  int ufshcd_hold(struct ufs_hba *hba, bool async);
>  void ufshcd_release(struct ufs_hba *hba);
>  
> +/* Expose UFS configfs API's */
> +#ifndef CONFIG_UFS_PROVISION
> +static inline void ufshcd_configfs_init(struct ufs_hba *hba, const char *name)
> +{
> +}
> +static inline void ufshcd_configfs_exit(struct ufs_hba *hba)
> +{
> +}
> +#else
> +void ufshcd_configfs_init(struct ufs_hba *hba, const char *name);
> +void ufshcd_configfs_exit(struct ufs_hba *hba);
> +#endif
> +
>  int ufshcd_map_desc_id_to_length(struct ufs_hba *hba, enum desc_idn desc_id,
>  	int *desc_length);
>  
>