S.M.A.R.T. temperature sensors have been supported for
years by userspace tools such as smarttools.
The temperature readout is however also a good fit for
Linux' hwmon subsystem. By adding a hwmon interface to dig
out SMART parameter 194, we can expose the drive temperature
as a standard hwmon sensor.
The idea came about when experimenting with NAS enclosures
that lack their own on-board sensors but instead piggy-back
the sensor found in the harddrive, if any, to decide on a
policy for driving the on-board fan.
The kernel thermal subsystem supports defining a thermal
policy for the enclosure using the device tree, see e.g.:
arch/arm/boot/dts/gemini-dlink-dns-313.dts
but this requires a proper hwmon sensor integrated with
the kernel.
This is a first attempt at providing a kernel-internal
hwmon sensor for ATA drives. It is possible to do the
same for SCSI, NVME etc, but their protocols and
peculiarities seem to require a per-subsystem implementation.
They would all end up in the same namespace using the
SCSI name such as "sd_0:0:0:0".
With this driver, the hard disk temperatur can be read from
sysfs:
> cd /sys/class/hwmon/hwmon0/
> cat temp1_input
38
This likely means that they can also be handled by
userspace tools such as lm_sensors in a uniform way
without need for any special tools such as "hddtemp"
(which seems dormant) though I haven't tested it.
This driver does not block any simultaneous use of
other SMART userspace tools, it's a both/and approach,
not either/or.
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
This is just me having some idea, so I wanted to toss it
out there in case people think it is useful. If you want
to kill the idea right now before I get any further with
it, this is the time to pitch in. You can also say if
you like it.
I included the smartmontools mailing list on the review,
it seemed relevant.
---
drivers/ata/Kconfig | 13 ++
drivers/ata/Makefile | 1 +
drivers/ata/libata-hwmon.c | 420 +++++++++++++++++++++++++++++++++++++
drivers/ata/libata-hwmon.h | 15 ++
drivers/ata/libata-scsi.c | 2 +
5 files changed, 451 insertions(+)
create mode 100644 drivers/ata/libata-hwmon.c
create mode 100644 drivers/ata/libata-hwmon.h
diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index 2b16e7c8fff3..8349101c7e53 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -59,6 +59,19 @@ config ATA_ACPI
You can disable this at kernel boot time by using the
option libata.noacpi=1
+config ATA_HWMON
+ bool "ATA S.M.A.R.T. HWMON support"
+ depends on HWMON
+ help
+ This options compiles in code to support temperature reading
+ from an ATA device using the S.M.A.R.T. (Self-Monitoring,
+ Analysis and Reporting Technology) support for temperature
+ sensors found in some hard drives. The drive will be probed
+ to figure out if it has a temperature sensor, and if it does
+ the kernel hardware monitor framework will be utilized to
+ interact with the sensor. This work orthogonal to any userspace
+ S.M.A.R.T. access tools.
+
config SATA_ZPODD
bool "SATA Zero Power Optical Disc Drive (ZPODD) support"
depends on ATA_ACPI && PM
diff --git a/drivers/ata/Makefile b/drivers/ata/Makefile
index d21cdd83f7ab..7a22b27c66c0 100644
--- a/drivers/ata/Makefile
+++ b/drivers/ata/Makefile
@@ -126,3 +126,4 @@ libata-$(CONFIG_ATA_SFF) += libata-sff.o
libata-$(CONFIG_SATA_PMP) += libata-pmp.o
libata-$(CONFIG_ATA_ACPI) += libata-acpi.o
libata-$(CONFIG_SATA_ZPODD) += libata-zpodd.o
+libata-$(CONFIG_ATA_HWMON) += libata-hwmon.o
diff --git a/drivers/ata/libata-hwmon.c b/drivers/ata/libata-hwmon.c
new file mode 100644
index 000000000000..fa1e4e472625
--- /dev/null
+++ b/drivers/ata/libata-hwmon.c
@@ -0,0 +1,420 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Hwmon client for ATA S.M.A.R.T. hard disk drivers
+ * (C) 2018 Linus Walleij
+ *
+ * This code is based on know-how and examples from the
+ * smartmontools by Bruce Allen, Christian Franke et al.
+ * (C) 2002-2018
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/hwmon.h>
+#include <linux/ata.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_cmnd.h>
+
+#include "libata-hwmon.h"
+
+#define ATA_MAX_SMART_ATTRS 30
+#define SMART_TEMP_PROP_194 194
+
+enum ata_temp_format {
+ ATA_TEMP_FMT_TT_XX_00_00_00_00,
+ ATA_TEMP_FMT_TT_XX_LL_HH_00_00,
+ ATA_TEMP_FMT_TT_LL_HH_00_00_00,
+ ATA_TEMP_FMT_TT_XX_LL_XX_HH_XX,
+ ATA_TEMP_FMT_TT_XX_HH_XX_LL_XX,
+ ATA_TEMP_FMT_TT_XX_LL_HH_CC_CC,
+ ATA_TEMP_FMT_UNKNOWN,
+};
+
+/**
+ * struct ata_hwmon - device instance state
+ * @hwmon_dev: associated hwmon device
+ */
+struct ata_hwmon {
+ struct device *dev;
+ struct device *hwmon_dev;
+ struct scsi_device *sdev;
+ enum ata_temp_format tfmt;
+};
+
+static umode_t ata_hwmon_is_visible(const void *data,
+ enum hwmon_sensor_types type,
+ u32 attr, int channel)
+{
+ switch (type) {
+ case hwmon_temp:
+ switch (attr) {
+ case hwmon_temp_input:
+ case hwmon_temp_min:
+ case hwmon_temp_max:
+ return S_IRUGO;
+ }
+ break;
+ default:
+ break;
+ }
+ return 0;
+}
+
+static int check_temp_word(u16 word)
+{
+ if (word <= 0x7f)
+ return 0x11; /* >= 0, signed byte or word */
+ if (word <= 0xff)
+ return 0x01; /* < 0, signed byte */
+ if (word > 0xff80)
+ return 0x10; /* < 0, signed word */
+ return 0x00;
+}
+
+static bool ata_check_temp_range(int t, u8 t1, u8 t2)
+{
+ int lo = (s8)t1;
+ int hi = (s8)t2;
+
+ /* This is obviously wrong */
+ if (lo > hi)
+ return false;
+
+ /*
+ * If -60 <= lo <= t <= hi <= 120 and
+ * and NOT lo == -1 and hi <= 0, then we have valid lo and hi
+ */
+ if (-60 <= lo && lo <= t && t <= hi && hi <= 120
+ && !(lo == -1 && hi <= 0)) {
+ return true;
+ }
+ return false;
+}
+
+static int ata_hwmon_detect_tempformat(struct ata_hwmon *ata, u8 *raw)
+{
+ s8 t;
+ u16 w0, w1, w2;
+ int ctw0;
+
+ /*
+ * Interpret the RAW temperature data:
+ * raw[0] is the temperature given as signed u8 on all known drives
+ *
+ * Search for possible min/max values
+ * This algorithm is a modified version from the smartmontools.
+ *
+ * [0][1][2][3][4][5] raw[]
+ * [ 0 ] [ 1 ] [ 2 ] word[]
+ * TT xx LL xx HH xx Hitachi/HGST
+ * TT xx HH xx LL xx Kingston SSDs
+ * TT xx LL HH 00 00 Maxtor, Samsung, Seagate, Toshiba
+ * TT LL HH 00 00 00 WDC
+ * TT xx LL HH CC CC WDC, CCCC=over temperature count
+ * (xx = 00/ff, possibly sign extension of lower byte)
+ *
+ * TODO: detect the 10x temperatures found on some Samsung
+ * drives. struct scsi_device contains manufacturer and model
+ * information.
+ */
+ w0 = raw[0] | raw[1] << 16;
+ w1 = raw[2] | raw[3] << 16;
+ w2 = raw[4] | raw[5] << 16;
+ t = (s8)raw[0];
+
+ /* If this is != 0, then w0 may contain something useful */
+ ctw0 = check_temp_word(w0);
+
+ /* This checks variants with zero in [4] [5] */
+ if (!w2) {
+ /* TT xx 00 00 00 00 */
+ if (!w1 && ctw0)
+ ata->tfmt = ATA_TEMP_FMT_TT_XX_00_00_00_00;
+ /* TT xx LL HH 00 00 */
+ else if (ctw0 &&
+ ata_check_temp_range(t, raw[2], raw[3]))
+ ata->tfmt = ATA_TEMP_FMT_TT_XX_LL_HH_00_00;
+ /* TT LL HH 00 00 00 */
+ else if (!raw[3] &&
+ ata_check_temp_range(t, raw[1], raw[2]))
+ ata->tfmt = ATA_TEMP_FMT_TT_LL_HH_00_00_00;
+ else
+ return -EINVAL;
+ } else if (ctw0) {
+ /*
+ * TT xx LL xx HH xx
+ * What the expression below does is to check that each word
+ * formed by [0][1], [2][3], and [4][5] is something little-
+ * endian s8 or s16 that could be meaningful.
+ */
+ if ((ctw0 & check_temp_word(w1) & check_temp_word(w2)) != 0x00)
+ if (ata_check_temp_range(t, raw[2], raw[4]))
+ ata->tfmt = ATA_TEMP_FMT_TT_XX_LL_XX_HH_XX;
+ else if (ata_check_temp_range(t, raw[4], raw[2]))
+ ata->tfmt = ATA_TEMP_FMT_TT_XX_HH_XX_LL_XX;
+ else
+ return -EINVAL;
+ /*
+ * TT xx LL HH CC CC
+ * Make sure the CC CC word is at least not negative, and that
+ * the max temperature is something >= 40, then it is probably
+ * the right format.
+ */
+ else if (w2 < 0x7fff) {
+ if (ata_check_temp_range(t, raw[2], raw[3]) &&
+ raw[3] >= 40)
+ ata->tfmt = ATA_TEMP_FMT_TT_XX_LL_HH_CC_CC;
+ else
+ return -EINVAL;
+ } else {
+ return -EINVAL;
+ }
+ } else {
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static void ata_hwmon_convert_temperatures(struct ata_hwmon *ata, u8 *raw,
+ int *t, int *lo, int *hi)
+{
+ *t = (s8)raw[0];
+
+ switch (ata->tfmt) {
+ case ATA_TEMP_FMT_TT_XX_00_00_00_00:
+ *lo = 0;
+ *hi = 0;
+ break;
+ case ATA_TEMP_FMT_TT_XX_LL_HH_00_00:
+ *lo = (s8)raw[2];
+ *hi = (s8)raw[3];
+ break;
+ case ATA_TEMP_FMT_TT_LL_HH_00_00_00:
+ *lo = (s8)raw[1];
+ *hi = (s8)raw[2];
+ break;
+ case ATA_TEMP_FMT_TT_XX_LL_XX_HH_XX:
+ *lo = (s8)raw[2];
+ *hi = (s8)raw[4];
+ break;
+ case ATA_TEMP_FMT_TT_XX_HH_XX_LL_XX:
+ *lo = (s8)raw[4];
+ *hi = (s8)raw[2];
+ break;
+ case ATA_TEMP_FMT_TT_XX_LL_HH_CC_CC:
+ *lo = (s8)raw[2];
+ *hi = (s8)raw[3];
+ break;
+ case ATA_TEMP_FMT_UNKNOWN:
+ *lo = 0;
+ *hi = 0;
+ break;
+ }
+}
+
+static int ata_hwmon_read_temp(struct ata_hwmon *ata, int *temp,
+ int *min, int *max)
+{
+ u8 scsi_cmd[MAX_COMMAND_SIZE];
+ int cmd_result;
+ u8 *argbuf = NULL;
+ struct scsi_sense_hdr sshdr;
+ u8 raw[6];
+ int ret;
+ u8 csum;
+ int i;
+
+ /* Send ATA command to read SMART values */
+ memset(scsi_cmd, 0, sizeof(scsi_cmd));
+ scsi_cmd[0] = ATA_16;
+ scsi_cmd[1] = (4 << 1); /* PIO Data-in */
+ /*
+ * No off.line or cc, read from dev, block count in sector count
+ * field.
+ */
+ scsi_cmd[2] = 0x0e;
+ scsi_cmd[4] = ATA_SMART_READ_VALUES;
+ scsi_cmd[6] = 1; /* Read 1 sector */
+ scsi_cmd[8] = 0; /* args[1]; */
+ scsi_cmd[10] = ATA_SMART_LBAM_PASS;
+ scsi_cmd[12] = ATA_SMART_LBAH_PASS;
+ scsi_cmd[14] = ATA_CMD_SMART;
+
+ argbuf = kmalloc(ATA_SECT_SIZE, GFP_KERNEL);
+ cmd_result = scsi_execute(ata->sdev, scsi_cmd, DMA_FROM_DEVICE,
+ argbuf, ATA_SECT_SIZE,
+ NULL, &sshdr, (10*HZ), 5, 0, 0, NULL);
+ if (cmd_result) {
+ dev_err(ata->dev, "error %d reading SMART values from device\n",
+ cmd_result);
+ ret = -EIO;
+ goto freebuf;
+ }
+
+ /* Checksum the read value table */
+ csum = 0;
+ for (i = 0; i < ATA_SECT_SIZE; i++)
+ csum += argbuf[i];
+ if (csum) {
+ dev_err(ata->dev, "checksum error reading SMART values\n");
+ ret = -EIO;
+ goto freebuf;
+ }
+
+ /* Loop over SMART attributes */
+ for (i = 0; i < ATA_MAX_SMART_ATTRS; i++) {
+ u8 id;
+ u16 flags;
+ u8 curr;
+ u8 worst;
+ int j;
+
+ id = argbuf[2 + i * 12];
+ if (!id)
+ continue;
+
+ flags = argbuf[3 + i * 12] | (argbuf[4 + i * 12] << 16);
+ /* Highest temperature since boot */
+ curr = argbuf[5 + i * 12];
+ /* Highest temperature ever */
+ worst = argbuf[6 + i * 12];
+ for (j = 0; j < 6; j++)
+ raw[j] = argbuf[7 + i * 12 + j];
+ dev_dbg(ata->dev, "ID: %d, FLAGS: %04x, current %d, worst %d, "
+ "RAW %02x %02x %02x %02x %02x %02x\n",
+ id, flags, curr, worst,
+ raw[0], raw[1], raw[2], raw[3], raw[4], raw[5]);
+
+ if (id == SMART_TEMP_PROP_194)
+ break;
+ }
+ if (i == ATA_MAX_SMART_ATTRS) {
+ ret = -ENOTSUPP;
+ goto freebuf;
+ }
+
+ if (ata->tfmt == ATA_TEMP_FMT_UNKNOWN) {
+ ret = ata_hwmon_detect_tempformat(ata, raw);
+ if (ret) {
+ dev_err(ata->dev,
+ "unable to determine temperature format\n");
+ ret = -ENOTSUPP;
+ goto freebuf;
+ }
+ }
+
+ ata_hwmon_convert_temperatures(ata, raw, temp, min, max);
+ dev_dbg(ata->dev, "temp = %d, min = %d, max = %d\n",
+ *temp, *min, *max);
+
+ ret = 0;
+
+freebuf:
+ kfree(argbuf);
+ return ret;
+}
+
+static int ata_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, long *val)
+{
+ struct ata_hwmon *ata = dev_get_drvdata(dev);
+ int temp, min, max;
+ int ret;
+
+ if (type != hwmon_temp)
+ return -EINVAL;
+
+ ret = ata_hwmon_read_temp(ata, &temp, &min, &max);
+ if (ret)
+ return ret;
+
+ switch (attr) {
+ case hwmon_temp_input:
+ *val = temp;
+ break;
+ case hwmon_temp_min:
+ *val = min;
+ break;
+ case hwmon_temp_max:
+ *val = max;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static const struct hwmon_ops ata_hwmon_ops = {
+ .is_visible = ata_hwmon_is_visible,
+ .read = ata_hwmon_read,
+};
+
+static const u32 ata_hwmon_temp_config[] = {
+ HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX,
+ 0,
+};
+
+static const struct hwmon_channel_info ata_hwmon_temp = {
+ .type = hwmon_temp,
+ .config = ata_hwmon_temp_config,
+};
+
+static const struct hwmon_channel_info *ata_hwmon_info[] = {
+ &ata_hwmon_temp,
+ NULL,
+};
+
+static const struct hwmon_chip_info ata_hwmon_devinfo = {
+ .ops = &ata_hwmon_ops,
+ .info = ata_hwmon_info,
+};
+
+int ata_hwmon_probe(struct scsi_device *sdev)
+{
+ struct device *dev = &sdev->sdev_gendev;
+ struct ata_hwmon *ata;
+ char *sname;
+ int t;
+ int dummy;
+ int ret;
+
+ ata = devm_kzalloc(dev, sizeof(*ata), GFP_KERNEL);
+ if (!ata)
+ return -ENOMEM;
+ ata->dev = dev;
+ ata->sdev = sdev;
+
+ /*
+ * If temperature reading is not supported in the SMART
+ * properties, we just bail out.
+ */
+ ata->tfmt = ATA_TEMP_FMT_UNKNOWN;
+ ret = ata_hwmon_read_temp(ata, &t, &dummy, &dummy);
+ if (ret == -ENOTSUPP)
+ return 0;
+ /* Any other error, return upward */
+ if (ret)
+ return ret;
+ dev_info(dev, "initial temperature %d degrees celsius\n", t);
+
+ /* Names the hwmon device something like "sd_0:0:0:0" */
+ sname = devm_kasprintf(dev, GFP_KERNEL, "sd_%s", dev_name(dev));
+ if (!sname)
+ return -ENOMEM;
+ ata->hwmon_dev =
+ devm_hwmon_device_register_with_info(dev, sname, ata,
+ &ata_hwmon_devinfo,
+ NULL);
+ if (IS_ERR(ata->hwmon_dev))
+ return PTR_ERR(ata->hwmon_dev);
+
+ dev_info(dev, "added hwmon sensor %s\n", sname);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(ata_hwmon_probe);
diff --git a/drivers/ata/libata-hwmon.h b/drivers/ata/libata-hwmon.h
new file mode 100644
index 000000000000..df56ba456345
--- /dev/null
+++ b/drivers/ata/libata-hwmon.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <scsi/scsi_device.h>
+
+#ifdef CONFIG_ATA_HWMON
+
+int ata_hwmon_probe(struct scsi_device *sdev);
+
+#else
+
+static inline int ata_hwmon_probe(struct scsi_device *sdev)
+{
+ return 0;
+}
+
+#endif
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 55b890d19780..a83075e4d3b3 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -54,6 +54,7 @@
#include "libata.h"
#include "libata-transport.h"
+#include "libata-hwmon.h"
#define ATA_SCSI_RBUF_SIZE 4096
@@ -4594,6 +4595,7 @@ void ata_scsi_scan_host(struct ata_port *ap, int sync)
if (!IS_ERR(sdev)) {
dev->sdev = sdev;
scsi_device_put(sdev);
+ ata_hwmon_probe(sdev);
} else {
dev->sdev = NULL;
}
--
2.17.1
