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

Evan Green
2018-07-09T17:49:24Z

Hi Sayali,
Thanks for the prompt spin.

On Thu, Jul 5, 2018 at 11:21 PM Sayali Lokhande <sayalil@codeaurora.org> wrote:
>
> This patch adds configfs support to provision ufs device at

s/ufs/UFS/

> 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@codeaurora.org>
> ---
> 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 — 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.

> + > /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.

> + 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?

> + 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".

> + }
> +
> + /* 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.

> + 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?

> + .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?

-Evan