Re: [PATCH 2/2 v2] scsi: ufs: use sysfs entry for health info

["gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>]

On Tue, Dec 19, 2017 at 02:46:44PM -0800, Jaegeuk Kim wrote:
> >From 3368207da5988b8fed4e41e6c0f49a60ac014222 Mon Sep 17 00:00:00 2001
> From: Jaegeuk Kim <jaegeuk@google.com>
> Date: Tue, 26 Sep 2017 20:53:48 -0700
> Subject: [PATCH 2/2] scsi: ufs: introduce sysfs entries exposing UFS health
>  info
> 
> This patch adds a new sysfs group, namely health, via:
> 
>    /sys/devices/soc/X.ufshc/health/
> 
> This directory contains the below entries, each of which shows an 8-bytes
> hex number representing different meanings defined by JEDEC specfication.
> 
> Users can simply read these entries to check how their underlying flash
> storage is getting reached out to its end of life. For example, if
> lifetimeA shows 0xb, it would be the right time to consider device swap.
> 
>  - length
>    : must be 25h
> 
>  - type
>    : must be 09h
> 
>  - eol
>    00h: Not defined
>    01h: Normal
>    02h: Warning
>    03h: Critical
> 
>  - lifetimeA/B
>    00h: Not defined
>    01h:  0% ~ 10% device life time used
>    02h: 10% ~ 20% device life time used
>    03h: 20% ~ 30% device life time used
>    04h: 30% ~ 40% device life time used
>    05h: 40% ~ 50% device life time used
>    06h: 50% ~ 60% device life time used
>    07h: 60% ~ 70% device life time used
>    08h: 70% ~ 80% device life time used
>    09h: 80% ~ 90% device life time used
>    0Ah: 90% ~ 100% device life time used
>    0Bh: Exceeded its maximum estimated device life time
> 
> Cc: Greg KH <gregkh@linuxfoundation.org>
> Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
> ---
>  Documentation/ABI/testing/sysfs-devices-soc-ufs | 25 +++++++++
>  MAINTAINERS                                     |  1 +
>  drivers/scsi/ufs/ufs.h                          |  2 +
>  drivers/scsi/ufs/ufshcd.c                       | 69 ++++++++++++++++++++++++-
>  drivers/scsi/ufs/ufshcd.h                       |  1 +
>  5 files changed, 97 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-devices-soc-ufs
> 
> diff --git a/Documentation/ABI/testing/sysfs-devices-soc-ufs b/Documentation/ABI/testing/sysfs-devices-soc-ufs
> new file mode 100644
> index 000000000000..313771a383e4
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-devices-soc-ufs
> @@ -0,0 +1,25 @@
> +What:		/sys/devices/soc/X.ufshc/health
> +Date:		September 2017
> +contact:	Jaegeuk Kim <jaegeuk@google.com>
> +Description:
> +		This directory contains health information reported by UFS.
> +		- length must be 25h
> +		- type must be 09h
> +		- eol represent
> +		  00h: Not defined
> +		  01h: Normal
> +		  02h: Warning
> +		  03h: Critical
> +		- lifetimeA/B
> +		  00h: Not defined
> +		  01h:  0% ~ 10% device life time used
> +		  02h: 10% ~ 20% device life time used
> +		  03h: 20% ~ 30% device life time used
> +		  04h: 30% ~ 40% device life time used
> +		  05h: 40% ~ 50% device life time used
> +		  06h: 50% ~ 60% device life time used
> +		  07h: 60% ~ 70% device life time used
> +		  08h: 70% ~ 80% device life time used
> +		  09h: 80% ~ 90% device life time used
> +		  0Ah: 90% ~ 100% device life time used
> +		  0Bh: Exceeded its maximum estimated device life time
> diff --git a/MAINTAINERS b/MAINTAINERS
> index aa71ab52fd76..947034319bb4 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -13999,6 +13999,7 @@ M:	Vinayak Holikatti <vinholikatti@gmail.com>
>  L:	linux-scsi@vger.kernel.org
>  S:	Supported
>  F:	Documentation/scsi/ufs.txt
> +F:	Documentation/ABI/testing/sysfs-devices-soc-ufs
>  F:	drivers/scsi/ufs/
>  
>  UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER DWC HOOKS
> diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
> index 54deeb754db5..1af541d56c7d 100644
> --- a/drivers/scsi/ufs/ufs.h
> +++ b/drivers/scsi/ufs/ufs.h
> @@ -154,6 +154,7 @@ enum desc_idn {
>  	QUERY_DESC_IDN_RFU_1		= 0x6,
>  	QUERY_DESC_IDN_GEOMETRY		= 0x7,
>  	QUERY_DESC_IDN_POWER		= 0x8,
> +	QUERY_DESC_IDN_HEALTH		= 0x9,
>  	QUERY_DESC_IDN_MAX,
>  };
>  
> @@ -169,6 +170,7 @@ enum ufs_desc_def_size {
>  	QUERY_DESC_INTERCONNECT_DEF_SIZE	= 0x06,
>  	QUERY_DESC_GEOMETRY_DEF_SIZE		= 0x44,
>  	QUERY_DESC_POWER_DEF_SIZE		= 0x62,
> +	QUERY_DESC_HEALTH_DEF_SIZE		= 0x25,
>  };
>  
>  /* Unit descriptor parameters offsets in bytes*/
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 12ff7daebb00..5cbb08fff0f4 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -2991,6 +2991,9 @@ int ufshcd_map_desc_id_to_length(struct ufs_hba *hba,
>  	case QUERY_DESC_IDN_RFU_1:
>  		*desc_len = 0;
>  		break;
> +	case QUERY_DESC_IDN_HEALTH:
> +		*desc_len = hba->desc_size.health_desc;
> +		break;
>  	default:
>  		*desc_len = 0;
>  		return -EINVAL;
> @@ -6298,6 +6301,11 @@ static void ufshcd_init_desc_sizes(struct ufs_hba *hba)
>  		&hba->desc_size.geom_desc);
>  	if (err)
>  		hba->desc_size.geom_desc = QUERY_DESC_GEOMETRY_DEF_SIZE;
> +
> +	err = ufshcd_read_desc_length(hba, QUERY_DESC_IDN_HEALTH, 0,
> +		&hba->desc_size.health_desc);
> +	if (err)
> +		hba->desc_size.health_desc = QUERY_DESC_HEALTH_DEF_SIZE;
>  }
>  
>  static void ufshcd_def_desc_sizes(struct ufs_hba *hba)
> @@ -6308,6 +6316,7 @@ static void ufshcd_def_desc_sizes(struct ufs_hba *hba)
>  	hba->desc_size.conf_desc = QUERY_DESC_CONFIGURATION_DEF_SIZE;
>  	hba->desc_size.unit_desc = QUERY_DESC_UNIT_DEF_SIZE;
>  	hba->desc_size.geom_desc = QUERY_DESC_GEOMETRY_DEF_SIZE;
> +	hba->desc_size.health_desc = QUERY_DESC_HEALTH_DEF_SIZE;
>  }
>  
>  /**
> @@ -7688,14 +7697,72 @@ static const struct attribute_group ufshcd_attr_group = {
>  	.attrs = ufshcd_attrs,
>  };
>  
> +struct health_attr {
> +	struct attribute attr;
> +	ssize_t (*show)(struct device *dev,
> +				struct health_attr *attr, char *buf);
> +	int byte_offset;
> +};
> +
> +static ssize_t health_attr_show(struct device *dev,
> +				struct health_attr *attr, char *buf)
> +{
> +	struct ufs_hba *hba = dev_get_drvdata(dev);
> +	int buff_len = hba->desc_size.health_desc;
> +	u8 desc_buf[hba->desc_size.health_desc];
> +	int err;
> +
> +	if (attr->byte_offset >= buff_len)
> +		return 0;
> +
> +	pm_runtime_get_sync(hba->dev);
> +	err = ufshcd_read_desc(hba, QUERY_DESC_IDN_HEALTH, 0,
> +					desc_buf, buff_len);
> +	pm_runtime_put_sync(hba->dev);
> +	if (err)
> +		return 0;
> +
> +	return scnprintf(buf, PAGE_SIZE, "0x%02x", desc_buf[attr->byte_offset]);
> +}
> +
> +#define HEALTH_ATTR_RO(_name, _byte_offset)				\
> +static struct health_attr ufs_health_##_name = {			\
> +	.attr = {.name = __stringify(_name), .mode = 0444},		\
> +	.show = health_attr_show,					\
> +	.byte_offset = _byte_offset,					\
> +}

This is a nice "hack" to make things simpler, but I worry about not
using the "normal" __ATTR_* macros here.  But I can't think of a simpler
way to do this now, except if you had a table of strings and offsets
that you then used to look up to get the offset based on the name of the
attribute.

Anyway, nice job, I'm just rambling:

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>