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Date: Tue, 17 Jul 2018 14:00:09 -0700
From: Evan Green <evgreen@...omium.org>
To: sayalil@...eaurora.org
Cc: subhashj@...eaurora.org, cang@...eaurora.org,
vivek.gautam@...eaurora.org,
Rajendra Nayak <rnayak@...eaurora.org>,
Vinayak Holikatti <vinholikatti@...il.com>,
jejb@...ux.vnet.ibm.com, martin.petersen@...cle.com,
asutoshd@...eaurora.org, riteshh@...eaurora.org,
linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
jlbec@...lplan.org, hch@....de
Subject: Re: [PATCH V6] scsi: ufs: Add configfs support for UFS provisioning
Hi Sayali,
On Mon, Jul 16, 2018 at 2:44 AM Sayali Lokhande <sayalil@...eaurora.org> 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 needs to be enabled for using this feature.
>
> Usage:
> 1) To read current configuration descriptor :
> cat /config/XXXX.ufshc/ufs_provision
> 2) To provision ufs device:
> echo <config_desc_buf> > /config/XXXX.ufshc/ufs_provision
>
> Signed-off-by: Sayali Lokhande <sayalil@...eaurora.org>
> ---
> Documentation/ABI/testing/configfs-driver-ufs | 18 +++
> drivers/scsi/ufs/Kconfig | 10 ++
> drivers/scsi/ufs/Makefile | 1 +
> drivers/scsi/ufs/ufs-configfs.c | 162 ++++++++++++++++++++++++++
> drivers/scsi/ufs/ufshcd.c | 2 +
> drivers/scsi/ufs/ufshcd.h | 19 +++
> 6 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/drivers/scsi/ufs/ufs-configfs.c b/drivers/scsi/ufs/ufs-configfs.c
> new file mode 100644
> index 0000000..3e9837a
> --- /dev/null
> +++ b/drivers/scsi/ufs/ufs-configfs.c
> @@ -0,0 +1,162 @@
> +// 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;
Can this ever return NULL? to_config_group() and
to_configfs_subsystem() guard against null, but container_of does not,
which would make hba a small negative value. The conditional would
needs to be subsys ? 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");
Maybe just fail, rather than successfully returning something unexpected.
> +
> + 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);
Same here, failing is probably better than returning unexpected text.
> +
> + 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)
> + 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)
> + 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;
> + }
> +
> + /* 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: 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 = 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_type = &ufscfg_type,
> + },
> + },
> +};
> +
> +int ufshcd_configfs_init(struct ufs_hba *hba, const char *name)
> +{
> + int ret;
> + struct configfs_subsystem *subsys = &hba->subsys;
> +
> + strncpy(ufscfg_subsys.su_group.cg_item.ci_namebuf, name, strlen(name));
> + subsys->su_group = ufscfg_subsys.su_group;
> + config_group_init(&subsys->su_group);
> + mutex_init(&subsys->su_mutex);
> + ret = configfs_register_subsystem(subsys);
Are the configfs folks okay with adding a new top level directory for
each host controller in the system? It might be better to have a
single top level directory of ufs, and then each controller as a
subdirectory underneath that. I'll defer to whatever the maintainers
think here.
> + if (ret)
> + pr_err("Error %d while registering subsystem %s\n",
> + ret,
> + subsys->su_group.cg_item.ci_namebuf);
> +
> + return ret;
> +}
> +
> +void ufshcd_configfs_exit(void)
> +{
> + configfs_unregister_subsystem(&ufscfg_subsys);
> +}
-Evan
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