[PATCH linux v6 0/3] Export 1-wire thermal sensors as hwmon device

[PATCH linux v6 0/3] Export 1-wire thermal sensors as hwmon device

[Jaghathiswari Rankappagounder Natarajan]

Hi Greg,
Please pull in this patchset into the tree. Thanks!

Summary of what this patchset does:

Our board has 4 DS18B20 1-wire temperature sensors. Each 1-wire bus and the
sensor under it is already configured against the Linux 1-wire driver
(called w1). They have a sysfs file(e.g.
/sys/bus/w1/devices/w1_bus_master1/28-000007704f4c/w1_slave) which, when read,
runs code to read the temperature. We'd like the temperatures to show up in
hwmon, so that the BMC IPMI sensor plumbing can forward those to host.

This patchset is based on top char-misc-next branch(from Greg KH's char-misc
git tree).

Tested:
Yes; On a board with 4 DS18B20 1-wire temperature sensors:
root@zaius:/sys/class/hwmon# ls
hwmon0  hwmon1  hwmon2  hwmon3  hwmon4  hwmon5
root@zaius:/sys/class/hwmon# cd hwmon0
root@zaius:/sys/class/hwmon/hwmon0# ls
device       name         subsystem    temp1_input  uevent
root@zaius:/sys/class/hwmon/hwmon0# cat temp1_input
24500
root@zaius:/sys/class/hwmon/hwmon0# cd ..
root@zaius:/sys/class/hwmon# cd hwmon1
root@zaius:/sys/class/hwmon/hwmon1# cat temp1_input
26562
root@zaius:/sys/class/hwmon/hwmon1# cd ..
root@zaius:/sys/class/hwmon# cd hwmon2
root@zaius:/sys/class/hwmon/hwmon2# cat temp1_input
27250
root@zaius:/sys/class/hwmon/hwmon2# cd ..
root@zaius:/sys/class/hwmon# cd hwmon3
root@zaius:/sys/class/hwmon/hwmon3# cat temp1_input
22250
root@zaius:/sys/class/hwmon/hwmon3#

Jaghathiswari Rankappagounder Natarajan (3):
  drivers: w1: add hwmon support structures
  drivers: w1: refactor w1_slave_show to make the temp reading
    functionality separate
  drivers: w1: add hwmon temp support for w1_therm

 drivers/w1/slaves/w1_therm.c | 164 +++++++++++++++++++++++++++++++++++--------
 drivers/w1/w1.c              |  18 ++++-
 include/linux/w1.h           |   4 ++
 3 files changed, 156 insertions(+), 30 deletions(-)

--
2.14.1.581.gf28d330327-goog

[PATCH linux v6 1/3] drivers: w1: add hwmon support structures

[Jaghathiswari Rankappagounder Natarajan]

This patch has changes to w1.h/w1.c generic files to add (optional) hwmon
support structures.

Signed-off-by: Jaghathiswari Rankappagounder Natarajan <jaghu@google.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Acked-by: Guenter Roeck <linux@roeck-us.net>
---
v2
- made changes to support hwmon_device_register_with_info mentioned by Guenter.

v3
- used IS_REACHABLE(CONFIG_HWMON).
- removed hwmon device first before removing slave.

v4
- moved && to be in the previous line.

v5
- no change.

v6
-rebased on top of char-misc-next branch.

 drivers/w1/w1.c    | 18 +++++++++++++++++-
 include/linux/w1.h |  4 ++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index 3c76e1ca4b83..0c2a5a8327bd 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -25,6 +25,7 @@
 #include <linux/sched.h>
 #include <linux/kthread.h>
 #include <linux/freezer.h>
+#include <linux/hwmon.h>

 #include <linux/atomic.h>

@@ -649,9 +650,24 @@ static int w1_family_notify(unsigned long action, struct w1_slave *sl)
 				return err;
 			}
 		}
-
+		if (IS_REACHABLE(CONFIG_HWMON) && fops->chip_info) {
+			struct device *hwmon
+				= hwmon_device_register_with_info(&sl->dev,
+						"w1_slave_temp", sl,
+						fops->chip_info,
+						NULL);
+			if (IS_ERR(hwmon)) {
+				dev_warn(&sl->dev,
+					 "could not create hwmon device\n");
+			} else {
+				sl->hwmon = hwmon;
+			}
+		}
 		break;
 	case BUS_NOTIFY_DEL_DEVICE:
+		if (IS_REACHABLE(CONFIG_HWMON) && fops->chip_info &&
+			    sl->hwmon)
+			hwmon_device_unregister(sl->hwmon);
 		if (fops->remove_slave)
 			sl->family->fops->remove_slave(sl);
 		if (fops->groups)
diff --git a/include/linux/w1.h b/include/linux/w1.h
index 90cbe7e65059..5b2972946dda 100644
--- a/include/linux/w1.h
+++ b/include/linux/w1.h
@@ -68,6 +68,7 @@ struct w1_reg_num {
  * @family: module for device family type
  * @family_data: pointer for use by the family module
  * @dev: kernel device identifier
+ * @hwmon: pointer to hwmon device
  *
  */
 struct w1_slave {
@@ -83,6 +84,7 @@ struct w1_slave {
 	struct w1_family	*family;
 	void			*family_data;
 	struct device		dev;
+	struct device		*hwmon;
 };

 typedef void (*w1_slave_found_callback)(struct w1_master *, u64);
@@ -250,11 +252,13 @@ void w1_remove_master_device(struct w1_bus_master *master);
  * @add_slave: add_slave
  * @remove_slave: remove_slave
  * @groups: sysfs group
+ * @chip_info: pointer to struct hwmon_chip_info
  */
 struct w1_family_ops {
 	int  (*add_slave)(struct w1_slave *sl);
 	void (*remove_slave)(struct w1_slave *sl);
 	const struct attribute_group **groups;
+	const struct hwmon_chip_info *chip_info;
 };

 /**
--
2.14.1.581.gf28d330327-goog

[PATCH linux v6 2/3] drivers: w1: refactor w1_slave_show to make the temp reading functionality separate

[Jaghathiswari Rankappagounder Natarajan]

Inside the w1_slave_show function refactor the code to read the temp
into a separate function.

Signed-off-by: Jaghathiswari Rankappagounder Natarajan <jaghu@google.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
---
v2
- made changes to support hwmon_device_register_with_info mentioned by Guenter.

v3
- used IS_REACHABLE(CONFIG_HWMON).
- removed hwmon device first before removing slave.

v4
- moved && to be in the previous line.

v5
- no change

v6
- rebased on top of char-misc-next branch

 drivers/w1/slaves/w1_therm.c | 82 +++++++++++++++++++++++++++-----------------
 1 file changed, 51 insertions(+), 31 deletions(-)

diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index cb3fc3c6b0d1..faddc2488c91 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -59,6 +59,12 @@ struct w1_therm_family_data {
 	atomic_t refcnt;
 };

+struct therm_info {
+	u8 rom[9];
+	u8 crc;
+	u8 verdict;
+};
+
 /* return the address of the refcnt in the family data */
 #define THERM_REFCNT(family_data) \
 	(&((struct w1_therm_family_data *)family_data)->refcnt)
@@ -422,33 +428,31 @@ static ssize_t w1_slave_store(struct device *device,
 	return ret ? : size;
 }

-static ssize_t w1_slave_show(struct device *device,
-	struct device_attribute *attr, char *buf)
+static ssize_t read_therm(struct device *device,
+			  struct w1_slave *sl, struct therm_info *info)
 {
-	struct w1_slave *sl = dev_to_w1_slave(device);
 	struct w1_master *dev = sl->master;
-	u8 rom[9], crc, verdict, external_power;
-	int i, ret, max_trying = 10;
-	ssize_t c = PAGE_SIZE;
+	u8 external_power;
+	int ret, max_trying = 10;
 	u8 *family_data = sl->family_data;

 	ret = mutex_lock_interruptible(&dev->bus_mutex);
 	if (ret != 0)
-		goto post_unlock;
+		goto error;

-	if (!sl->family_data) {
+	if (!family_data) {
 		ret = -ENODEV;
-		goto pre_unlock;
+		goto mt_unlock;
 	}

 	/* prevent the slave from going away in sleep */
 	atomic_inc(THERM_REFCNT(family_data));
-	memset(rom, 0, sizeof(rom));
+	memset(info->rom, 0, sizeof(info->rom));

 	while (max_trying--) {

-		verdict = 0;
-		crc = 0;
+		info->verdict = 0;
+		info->crc = 0;

 		if (!w1_reset_select_slave(sl)) {
 			int count = 0;
@@ -474,47 +478,69 @@ static ssize_t w1_slave_show(struct device *device,
 				sleep_rem = msleep_interruptible(tm);
 				if (sleep_rem != 0) {
 					ret = -EINTR;
-					goto post_unlock;
+					goto dec_refcnt;
 				}

 				ret = mutex_lock_interruptible(&dev->bus_mutex);
 				if (ret != 0)
-					goto post_unlock;
+					goto dec_refcnt;
 			} else if (!w1_strong_pullup) {
 				sleep_rem = msleep_interruptible(tm);
 				if (sleep_rem != 0) {
 					ret = -EINTR;
-					goto pre_unlock;
+					goto dec_refcnt;
 				}
 			}

 			if (!w1_reset_select_slave(sl)) {

 				w1_write_8(dev, W1_READ_SCRATCHPAD);
-				count = w1_read_block(dev, rom, 9);
+				count = w1_read_block(dev, info->rom, 9);
 				if (count != 9) {
 					dev_warn(device, "w1_read_block() "
 						"returned %u instead of 9.\n",
 						count);
 				}

-				crc = w1_calc_crc8(rom, 8);
+				info->crc = w1_calc_crc8(info->rom, 8);

-				if (rom[8] == crc)
-					verdict = 1;
+				if (info->rom[8] == info->crc)
+					info->verdict = 1;
 			}
 		}

-		if (verdict)
+		if (info->verdict)
 			break;
 	}

+dec_refcnt:
+	atomic_dec(THERM_REFCNT(family_data));
+mt_unlock:
+	mutex_unlock(&dev->bus_mutex);
+error:
+	return ret;
+}
+
+static ssize_t w1_slave_show(struct device *device,
+			     struct device_attribute *attr, char *buf)
+{
+	struct w1_slave *sl = dev_to_w1_slave(device);
+	struct therm_info info;
+	u8 *family_data = sl->family_data;
+	int ret, i;
+	ssize_t c = PAGE_SIZE;
+	u8 fid = sl->family->fid;
+
+	ret = read_therm(device, sl, &info);
+	if (ret)
+		return ret;
+
 	for (i = 0; i < 9; ++i)
-		c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]);
+		c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", info.rom[i]);
 	c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
-		      crc, (verdict) ? "YES" : "NO");
-	if (verdict)
-		memcpy(family_data, rom, sizeof(rom));
+		      info.crc, (info.verdict) ? "YES" : "NO");
+	if (info.verdict)
+		memcpy(family_data, info.rom, sizeof(info.rom));
 	else
 		dev_warn(device, "Read failed CRC check\n");

@@ -523,14 +549,8 @@ static ssize_t w1_slave_show(struct device *device,
 			      ((u8 *)family_data)[i]);

 	c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
-		w1_convert_temp(rom, sl->family->fid));
+			w1_convert_temp(info.rom, fid));
 	ret = PAGE_SIZE - c;
-
-pre_unlock:
-	mutex_unlock(&dev->bus_mutex);
-
-post_unlock:
-	atomic_dec(THERM_REFCNT(family_data));
 	return ret;
 }

--
2.14.1.581.gf28d330327-goog

[PATCH linux v6 3/3] drivers: w1: add hwmon temp support for w1_therm

[Jaghathiswari Rankappagounder Natarajan]

This change adds hwmon temp support for w1_therm.

Signed-off-by: Jaghathiswari Rankappagounder Natarajan <jaghu@google.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Acked-by: Guenter Roeck <linux@roeck-us.net>
---
v2
- make changes to support hwmon_device_register_with_info mentioned by Guenter.

v3
- used IS_REACHABLE()
- rearranged the code to not require forward declarations
- used family_data
- incremented the reference count with the bus mutex locked
- corrected indentation
- removed dev_warn message
- simplified returning mode
- removed write function

v4
- used W1_CHIP_INFO
- corrected formatting

v5
- no change

v6
- rebased on top of char-misc-next branch

 drivers/w1/slaves/w1_therm.c | 86 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)

diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index faddc2488c91..259525c3382a 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -29,6 +29,7 @@
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/delay.h>
+#include <linux/hwmon.h>

 #include <linux/w1.h>

@@ -113,19 +114,72 @@ static struct attribute *w1_ds28ea00_attrs[] = {
 	&dev_attr_w1_seq.attr,
 	NULL,
 };
+
 ATTRIBUTE_GROUPS(w1_therm);
 ATTRIBUTE_GROUPS(w1_ds28ea00);

+#if IS_REACHABLE(CONFIG_HWMON)
+static int w1_read_temp(struct device *dev, u32 attr, int channel,
+			long *val);
+
+static umode_t w1_is_visible(const void *_data, enum hwmon_sensor_types type,
+			     u32 attr, int channel)
+{
+	return attr == hwmon_temp_input ? 0444 : 0;
+}
+
+static int w1_read(struct device *dev, enum hwmon_sensor_types type,
+		   u32 attr, int channel, long *val)
+{
+	switch (type) {
+	case hwmon_temp:
+		return w1_read_temp(dev, attr, channel, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static const u32 w1_temp_config[] = {
+	HWMON_T_INPUT,
+	0
+};
+
+static const struct hwmon_channel_info w1_temp = {
+	.type = hwmon_temp,
+	.config = w1_temp_config,
+};
+
+static const struct hwmon_channel_info *w1_info[] = {
+	&w1_temp,
+	NULL
+};
+
+static const struct hwmon_ops w1_hwmon_ops = {
+	.is_visible = w1_is_visible,
+	.read = w1_read,
+};
+
+static const struct hwmon_chip_info w1_chip_info = {
+	.ops = &w1_hwmon_ops,
+	.info = w1_info,
+};
+#define W1_CHIPINFO	(&w1_chip_info)
+#else
+#define W1_CHIPINFO	NULL
+#endif
+
 static struct w1_family_ops w1_therm_fops = {
 	.add_slave	= w1_therm_add_slave,
 	.remove_slave	= w1_therm_remove_slave,
 	.groups		= w1_therm_groups,
+	.chip_info	= W1_CHIPINFO,
 };

 static struct w1_family_ops w1_ds28ea00_fops = {
 	.add_slave	= w1_therm_add_slave,
 	.remove_slave	= w1_therm_remove_slave,
 	.groups		= w1_ds28ea00_groups,
+	.chip_info	= W1_CHIPINFO,
 };

 static struct w1_family w1_therm_family_DS18S20 = {
@@ -554,6 +608,38 @@ static ssize_t w1_slave_show(struct device *device,
 	return ret;
 }

+#if IS_REACHABLE(CONFIG_HWMON)
+static int w1_read_temp(struct device *device, u32 attr, int channel,
+			long *val)
+{
+	struct w1_slave *sl = dev_get_drvdata(device);
+	struct therm_info info;
+	u8 fid = sl->family->fid;
+	int ret;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		ret = read_therm(device, sl, &info);
+		if (ret)
+			return ret;
+
+		if (!info.verdict) {
+			ret = -EIO;
+			return ret;
+		}
+
+		*val = w1_convert_temp(info.rom, fid);
+		ret = 0;
+		break;
+	default:
+		ret = -EOPNOTSUPP;
+		break;
+	}
+
+	return ret;
+}
+#endif
+
 #define W1_42_CHAIN	0x99
 #define W1_42_CHAIN_OFF	0x3C
 #define W1_42_CHAIN_OFF_INV	0xC3
--
2.14.1.581.gf28d330327-goog

Re: [PATCH linux v6 0/3] Export 1-wire thermal sensors as hwmon device

[Greg KH]

On Wed, Aug 30, 2017 at 04:34:32PM -0700, Jaghathiswari Rankappagounder Natarajan wrote:
> Hi Greg,
> Please pull in this patchset into the tree. Thanks!

Thanks for the reworks, all now queued up.

greg k-h