Re: [PATCH V5 2/2] scsi: ufs: Add configfs support for ufs provisioning

[Sayali Lokhande]

Hi Evan,


On 7/9/2018 11:18 PM, Evan Green wrote:
> Hi Sayali,
> Thanks for the prompt spin.
>
> On Thu, Jul 5, 2018 at 11:21 PM Sayali Lokhande <sayalil@xxxxxxxxxxxxxx> wrote:
> > This patch adds configfs support to provision ufs device at
> s/ufs/UFS/
Will update.
> > 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 needs to be enabled for using this feature.
> >
> > Usage:
> > 1) To read current configuration descriptor :
> >     cat /config/ufshcd/ufs_provision
> > 2) To provision ufs device:
> >     echo <config_desc_buf> > /config/ufshcd/ufs_provision
> >
> > Signed-off-by: Sayali Lokhande <sayalil@xxxxxxxxxxxxxx>
> > ---
> >   Documentation/ABI/testing/configfs-driver-ufs |  18 +++
> >   drivers/scsi/ufs/Makefile                     |   1 +
> >   drivers/scsi/ufs/ufs-configfs.c               | 172 ++++++++++++++++++++++++++
> >   drivers/scsi/ufs/ufshcd.c                     |   2 +
> >   drivers/scsi/ufs/ufshcd.h                     |  19 +++
> >   5 files changed, 212 insertions(+)
> >   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..dd16842
> > --- /dev/null
> > +++ b/Documentation/ABI/testing/configfs-driver-ufs
> > @@ -0,0 +1,18 @@
> > +What:          /config/ufshcd/ufs_provision
> > +Date:          Jun 2018
> > +KernelVersion: 4.14
> > +Description:
> > +               This file shows the current ufs configuration descriptor 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 â Unit Descriptor configurable parameters from specs for
> Can this be a regular dash, rather than some sort of exotic 0xE2 byte.
>
> > +               description of each configuration descriptor parameter.
> > +               Configuration descriptor buffer needs to be passed in space separated
> > +               format specificied as below:
> > +               echo <bLength> <bDescriptorIDN> <bConfDescContinue> <bBootEnable>
> > +               <bDescrAccessEn> <bInitPowerMode> <bHighPriorityLUN>
> > +               <bSecureRemovalType> <bInitActiveICCLevel> <wPeriodicRTCUpdate>
> > +               <0Bh:0Fh_ReservedAs_0> <bLUEnable> <bBootLunID> <bLUWriteProtect>
> > +               <bMemoryType> <dNumAllocUnits> <bDataReliability> <bLogicalBlockSize>
> > +               <bProvisioningType> <wContextCapabilities> <0Dh:0Fh_ReservedAs_0>
> I wonder if at this point we should be using a binary attribute rather
> than a text one. Since now you're basically just converting text to
> bytes, it's not very human anymore.
Use of binary attr was ruled out before. Pasting previous comments from 
Greg :
"binary attributes are meant for hardware value pass-through" type stuff.
Unless this is "raw" data straight from the hardware, binary does not work.
> > +               > /config/ufshcd/ufs_provision
> > diff --git a/drivers/scsi/ufs/Makefile b/drivers/scsi/ufs/Makefile
> > index 918f579..d438e74 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_CONFIGFS_FS) += 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..7d207fc
> > --- /dev/null
> > +++ b/drivers/scsi/ufs/ufs-configfs.c
> > @@ -0,0 +1,172 @@
> > +// 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 ? hba : NULL;
> > +}
> > +
> > +static ssize_t ufs_provision_show(struct config_item *item, char *buf)
> > +{
> > +       u8 desc_buf[QUERY_DESC_CONFIGURATION_DEF_SIZE] = {0};
> > +       int buff_len = QUERY_DESC_CONFIGURATION_DEF_SIZE;
> > +       int i, ret, curr_len = 0;
> > +       struct ufs_hba *hba = config_item_to_hba(item);
> > +
> > +       if (!hba)
> > +               return snprintf(buf, PAGE_SIZE, "ufs hba is NULL!\n");
> > +
> > +       ret = ufshcd_query_descriptor_retry(hba, UPIU_QUERY_OPCODE_READ_DESC,
> > +               QUERY_DESC_IDN_CONFIGURATION, 0, 0, desc_buf, &buff_len);
> > +
> > +       if (ret)
> > +               return snprintf(buf, PAGE_SIZE,
> > +               "Failed reading descriptor. desc_idn %d, opcode %x ret %d\n",
> > +               QUERY_DESC_IDN_CONFIGURATION,
> > +               UPIU_QUERY_OPCODE_READ_DESC, ret);
> > +
> > +       for (i = 0; i < buff_len; i++)
> > +               curr_len += snprintf((buf + curr_len), (PAGE_SIZE - curr_len),
> > +                               "0x%x ", desc_buf[i]);
> > +
> > +       return curr_len;
> > +}
> > +
> > +ssize_t ufshcd_desc_configfs_store(struct ufs_hba *hba,
> > +               const char *buf, size_t count)
> > +{
> > +       char *strbuf;
> > +       char *strbuf_copy;
> > +       u8 desc_buf[QUERY_DESC_CONFIGURATION_DEF_SIZE] = {0};
> > +       int buff_len = QUERY_DESC_CONFIGURATION_DEF_SIZE;
> > +       char *token;
> > +       int i, ret, value;
> > +       u32 bConfigDescrLock = 0;
> > +
> > +       /* reserve one byte for null termination */
> > +       strbuf = kmalloc(count + 1, GFP_KERNEL);
> > +       if (!strbuf)
> > +               return -ENOMEM;
> > +
> > +       strbuf_copy = strbuf;
> > +       strlcpy(strbuf, buf, count + 1);
> > +
> > +       if (!hba)
> > +               goto out;
> > +
> > +       /* 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, &bConfigDescrLock);
> > +       if (ret) {
> > +               dev_err(hba->dev, "%s: Failed reading bConfigDescrLock %d, cannot re-provision device!\n",
> > +                       __func__, ret);
> I think ufshcd_query_attr has its own prints on failure, we probably
> don't need this one.
Will check and update.
> > +               goto out;
> > +       }
> > +       if (bConfigDescrLock) {
> > +               dev_err(hba->dev, "%s: bConfigDescrLock already set to %u, cannot re-provision device!\n",
> > +               __func__, bConfigDescrLock);
> > +               goto out;
> > +       }
> > +
> > +       for (i = 0; i < QUERY_DESC_CONFIGURATION_DEF_SIZE; i++) {
> > +               token = strsep(&strbuf, " ");
> > +               if (!token && i) {
> > +                       dev_dbg(hba->dev, "%s: token %s, i %d\n",
> > +                               __func__, token, i);
> You're printing token, which you know to be null. Is this print really useful?
Will check and update/remove this print.
> > +                       break;
> > +               }
> > +
> > +               ret = kstrtoint(token, 0, &value);
> > +               if (ret) {
> > +                       dev_err(hba->dev, "%s: kstrtoint failed %d %s\n",
> > +                               __func__, ret, token);
> > +                       break;
> > +               }
> > +               desc_buf[i] = (u8)value;
> > +               dev_dbg(hba->dev, " desc_buf[%d] 0x%x", i, desc_buf[i]);
> This print is probably a bit noisy. If you really want to dump the
> contents in the debug spew there's a print_hex_dump you can do after
> you break out of the loop. Then you could also remove the print for
> "token %s, i %d".
Will check and update.
> > +       }
> > +
> > +       /* Write configuration descriptor to provision ufs */
> > +       ret = ufshcd_query_descriptor_retry(hba, UPIU_QUERY_OPCODE_WRITE_DESC,
> > +               QUERY_DESC_IDN_CONFIGURATION, 0, 0, desc_buf, &buff_len);
> > +
> > +       if (ret)
> > +               dev_err(hba->dev, "%s: Failed writing descriptor. desc_idn %d, opcode %x ret %d\n",
> > +               __func__, QUERY_DESC_IDN_CONFIGURATION,
> > +               UPIU_QUERY_OPCODE_WRITE_DESC, ret);
> This is basically already covered by prints inside
> ufshcd_query_descriptor_retry.
Will update.
> > +       else
> > +               dev_err(hba->dev, "%s: UFS Provisioning done, reboot now!\n",
> > +               __func__);
> > +
> > +out:
> > +       kfree(strbuf_copy);
> > +       return count;
> > +}
> > +
> > +static ssize_t ufs_provision_store(struct config_item *item,
> > +               const char *buf, size_t count)
> > +{
> > +       struct ufs_hba *hba = config_item_to_hba(item);
> > +
> > +       return ufshcd_desc_configfs_store(hba, buf, count);
> > +}
> > +
> > +static struct configfs_attribute ufshcd_attr_provision = {
> > +       .ca_name        = "ufs_provision",
> > +       .ca_mode        = 0666,
> This seems too permissive. You don't want just anybody to be able to
> re-provision the disk. Maybe 0644?
Agreed. will update.
> > +       .ca_owner       = THIS_MODULE,
> > +       .show           = ufs_provision_show,
> > +       .store          = ufs_provision_store,
> > +};
> > +
> > +static struct configfs_attribute *ufshcd_attrs[] = {
> > +       &ufshcd_attr_provision,
> > +       NULL,
> > +};
> > +
> > +static struct config_item_type ufscfg_type = {
> > +       .ct_attrs       = ufshcd_attrs,
> > +       .ct_owner       = THIS_MODULE,
> > +};
> > +
> > +static struct configfs_subsystem ufscfg_subsys = {
> > +       .su_group = {
> > +               .cg_item = {
> > +                       .ci_namebuf = "ufshcd",
> > +                       .ci_type = &ufscfg_type,
> > +               },
> > +       },
> > +};
> > +
> > +int ufshcd_configfs_init(struct ufs_hba *hba)
> > +{
> > +       int ret;
> > +       struct configfs_subsystem *subsys = &hba->subsys;
> > +
> > +       subsys->su_group = ufscfg_subsys.su_group;
> > +       config_group_init(&subsys->su_group);
> > +       mutex_init(&subsys->su_mutex);
> > +       ret = configfs_register_subsystem(subsys);
> Wait so for every host controller, you register a subsystem called
> "ufshcd"? Won't that result in a naming conflict when the second
> controller comes along? I was expecting to see subsystem registration
> happen once, probably in a driver init function, and then some sort of
> device specific registration happen here. You'd need a unique name for
> each controller, maybe the device name itself?
Agreed. Will check and pass device name itself during init.
> -Evan