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[PATCH linux v4 0/3] Export 1-wire thermal sensors as hwmon device

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  [PATCH linux v4 0/3] Export 1-wire thermal sensors as hwmon device Jaghathiswari Rankappagounder Natarajan <jaghu@google.com> - 2017-07-14 00:50 +0200
    [PATCH linux v4 3/3] drivers: w1: add hwmon temp support for w1_therm Jaghathiswari Rankappagounder Natarajan <jaghu@google.com> - 2017-07-14 00:50 +0200
      Re: [PATCH linux v4 3/3] drivers: w1: add hwmon temp support for  w1_therm Guenter Roeck <linux@roeck-us.net> - 2017-07-14 04:50 +0200
    [PATCH linux v4 2/3] drivers: w1: refactor w1_slave_show to make the temp reading functionality separate Jaghathiswari Rankappagounder Natarajan <jaghu@google.com> - 2017-07-14 00:50 +0200

#1686973 — [PATCH linux v4 0/3] Export 1-wire thermal sensors as hwmon device

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 patch(version 4) is to address the comments provided by Guenter for
version 3. The changes in version 4 are mentioned in the individual patches.

This patchset is based on linux mainline version v4.10.

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 ++++-
 drivers/w1/w1.h              |   2 +
 drivers/w1/w1_family.h       |   2 +
 4 files changed, 156 insertions(+), 30 deletions(-)

--
2.13.2.932.g7449e964c-goog

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#1686975 — [PATCH linux v4 3/3] drivers: w1: add hwmon temp support for w1_therm

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>
---
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

 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 64e6a8f38410..c99886ac1dbf 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 "../w1.h"
 #include "../w1_int.h"
@@ -118,19 +119,72 @@ 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 = {
@@ -559,6 +613,38 @@ 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
--
2.13.2.932.g7449e964c-goog

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#1687035 — Re: [PATCH linux v4 3/3] drivers: w1: add hwmon temp support for w1_therm

On Thu, Jul 13, 2017 at 03:41:07PM -0700, Jaghathiswari Rankappagounder Natarajan wrote:
> 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
> 
>  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 64e6a8f38410..c99886ac1dbf 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 "../w1.h"
>  #include "../w1_int.h"
> @@ -118,19 +119,72 @@ 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 = {
> @@ -559,6 +613,38 @@ 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
> --
> 2.13.2.932.g7449e964c-goog
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

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#1686976 — [PATCH linux v4 2/3] drivers: w1: refactor w1_slave_show to make the temp reading functionality separate

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: Evgeniy Polyakov <zbr@ioremap.net>
Acked-by: Guenter Roeck <linux@roeck-us.net>
---
v2
- no changes

v3
- changed code so that the refcount is incremented with the bus mutex locked.

v4
- no changes

 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 82611f197b0a..64e6a8f38410 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -64,6 +64,12 @@ 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)
@@ -427,33 +433,31 @@ 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;
@@ -479,47 +483,69 @@ 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");

@@ -528,14 +554,8 @@ 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;
 }

--
2.13.2.932.g7449e964c-goog

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