[PATCH 1/4] Documentation: w1_therm: clearly state about binary value for precision

[PATCH 1/4] Documentation: w1_therm: clearly state about binary value for precision

[Mariusz Bialonczyk]

Signed-off-by: Mariusz Bialonczyk <manio@skyboo.net>
---
 Documentation/w1/slaves/w1_therm | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/w1/slaves/w1_therm b/Documentation/w1/slaves/w1_therm
index d1f93af..e10cd91 100644
--- a/Documentation/w1/slaves/w1_therm
+++ b/Documentation/w1/slaves/w1_therm
@@ -42,6 +42,7 @@ SRAM, so it is reset when the sensor gets power-cycled.
 To store the current precision configuration into EEPROM, the value 0
 has to be written to the sysfs w1_slave file. Since the EEPROM has a limited
 amount of writes (>50k), this command should be used wisely.
+Note: this precision value has to be a binary one-byte value, not ASCII.
 
 The module parameter strong_pullup can be set to 0 to disable the
 strong pullup, 1 to enable autodetection or 2 to force strong pullup.
-- 
2.9.3

[PATCH 2/4] w1: add missing DS2413 documentation

[Mariusz Bialonczyk]

Signed-off-by: Mariusz Bialonczyk <manio@skyboo.net>
---
 Documentation/w1/slaves/00-INDEX  |  2 ++
 Documentation/w1/slaves/w1_ds2413 | 50 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)
 create mode 100644 Documentation/w1/slaves/w1_ds2413

diff --git a/Documentation/w1/slaves/00-INDEX b/Documentation/w1/slaves/00-INDEX
index 6e18c70..cbcca1d 100644
--- a/Documentation/w1/slaves/00-INDEX
+++ b/Documentation/w1/slaves/00-INDEX
@@ -2,6 +2,8 @@
 	- This file
 w1_therm
 	- The Maxim/Dallas Semiconductor ds18*20 temperature sensor.
+w1_ds2413
+	- The Maxim/Dallas Semiconductor ds2413 dual channel addressable switch.
 w1_ds2423
 	- The Maxim/Dallas Semiconductor ds2423 counter device.
 w1_ds28e04
diff --git a/Documentation/w1/slaves/w1_ds2413 b/Documentation/w1/slaves/w1_ds2413
new file mode 100644
index 0000000..936263a
--- /dev/null
+++ b/Documentation/w1/slaves/w1_ds2413
@@ -0,0 +1,50 @@
+Kernel driver w1_ds2413
+=======================
+
+Supported chips:
+  * Maxim DS2413 1-Wire Dual Channel Addressable Switch
+
+supported family codes:
+        W1_FAMILY_DS2413        0x3A
+
+Author: Mariusz Bialonczyk <manio@skyboo.net>
+
+Description
+-----------
+
+The DS2413 chip has two open-drain outputs (PIO A and PIO B).
+Support is provided through the sysfs files "output" and "state".
+
+Reading state
+-------------
+The "state" file provides one-byte value which is in the same format as for
+the chip PIO_ACCESS_READ command (refer the datasheet for details):
+
+Bit 0:   PIOA Pin State
+Bit 1:   PIOA Output Latch State
+Bit 2:   PIOB Pin State
+Bit 3:   PIOB Output Latch State
+Bit 4-7: Complement of Bit 3 to Bit 0 (verified by the kernel module)
+
+This file is readonly.
+
+Writing output
+--------------
+You can set the PIO pins using the "output" file.
+It is writable, you can write one-byte value to this sysfs file.
+Similarly the byte format is the same as for the PIO_ACCESS_WRITE command:
+
+Bit 0:   PIOA
+Bit 1:   PIOB
+Bit 2-7: No matter (driver will set it to "1"s)
+
+
+The chip has some kind of basic protection against transmission errors.
+When reading the state, there is a four complement bits.
+The driver is checking this complement, and when it is wrong then it is
+returning I/O error.
+
+When writing output, the master must repeat the PIO Output Data byte in
+its inverted form and it is waiting for a confirmation.
+If the write is unsuccessful for three times, the write also returns
+I/O error.
-- 
2.9.3

[PATCH 3/4] w1: add support for DS2438 Smart Battery Monitor

[Mariusz Bialonczyk]

Signed-off-by: Mariusz Bialonczyk <manio@skyboo.net>
---
 drivers/w1/slaves/Kconfig     |   6 +
 drivers/w1/slaves/Makefile    |   1 +
 drivers/w1/slaves/w1_ds2438.c | 372 ++++++++++++++++++++++++++++++++++++++++++
 drivers/w1/w1_family.h        |   1 +
 4 files changed, 380 insertions(+)
 create mode 100644 drivers/w1/slaves/w1_ds2438.c

diff --git a/drivers/w1/slaves/Kconfig b/drivers/w1/slaves/Kconfig
index cfe74d0..9b4a797 100644
--- a/drivers/w1/slaves/Kconfig
+++ b/drivers/w1/slaves/Kconfig
@@ -78,6 +78,12 @@ config W1_SLAVE_DS2433_CRC
 	  Each block has 30 bytes of data and a two byte CRC16.
 	  Full block writes are only allowed if the CRC is valid.
 
+config W1_SLAVE_DS2438
+	tristate "DS2438 Smart Battery Monitor 0x26 family support"
+	help
+	  Say Y here if you want to use a 1-wire
+	  DS2438 Smart Battery Monitor device support
+
 config W1_SLAVE_DS2760
 	tristate "Dallas 2760 battery monitor chip (HP iPAQ & others)"
 	help
diff --git a/drivers/w1/slaves/Makefile b/drivers/w1/slaves/Makefile
index 1e9989a..7ad7a2c 100644
--- a/drivers/w1/slaves/Makefile
+++ b/drivers/w1/slaves/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_W1_SLAVE_DS2406)	+= w1_ds2406.o
 obj-$(CONFIG_W1_SLAVE_DS2423)	+= w1_ds2423.o
 obj-$(CONFIG_W1_SLAVE_DS2431)	+= w1_ds2431.o
 obj-$(CONFIG_W1_SLAVE_DS2433)	+= w1_ds2433.o
+obj-$(CONFIG_W1_SLAVE_DS2438)	+= w1_ds2438.o
 obj-$(CONFIG_W1_SLAVE_DS2760)	+= w1_ds2760.o
 obj-$(CONFIG_W1_SLAVE_DS2780)	+= w1_ds2780.o
 obj-$(CONFIG_W1_SLAVE_DS2781)	+= w1_ds2781.o
diff --git a/drivers/w1/slaves/w1_ds2438.c b/drivers/w1/slaves/w1_ds2438.c
new file mode 100644
index 0000000..5092b35
--- /dev/null
+++ b/drivers/w1/slaves/w1_ds2438.c
@@ -0,0 +1,372 @@
+/*
+ * 1-Wire implementation for the ds2438 chip
+ *
+ * Copyright (c) 2017 Mariusz Bialonczyk <manio@skyboo.net>
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2. See the file COPYING for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/types.h>
+#include <linux/delay.h>
+
+#include "../w1.h"
+#include "../w1_family.h"
+
+#define W1_DS2438_RETRIES		3
+
+/* Memory commands */
+#define W1_DS2438_READ_SCRATCH		0xBE
+#define W1_DS2438_WRITE_SCRATCH		0x4E
+#define W1_DS2438_COPY_SCRATCH		0x48
+#define W1_DS2438_RECALL_MEMORY		0xB8
+/* Register commands */
+#define W1_DS2438_CONVERT_TEMP		0x44
+#define W1_DS2438_CONVERT_VOLTAGE	0xB4
+
+#define DS2438_PAGE_SIZE		8
+#define DS2438_ADC_INPUT_VAD		0
+#define DS2438_ADC_INPUT_VDD		1
+#define DS2438_MAX_CONVERSION_TIME	10		/* ms */
+
+/* Page #0 definitions */
+#define DS2438_STATUS_REG		0x00		/* Status/Configuration Register */
+	#define DS2438_STATUS_IAD	(1 << 0)	/* Current A/D Control Bit */
+	#define DS2438_STATUS_CA	(1 << 1)	/* Current Accumulator Configuration */
+	#define DS2438_STATUS_EE	(1 << 2)	/* Current Accumulator Shadow Selector bit */
+	#define DS2438_STATUS_AD	(1 << 3)	/* Voltage A/D Input Select Bit */
+	#define DS2438_STATUS_TB	(1 << 4)	/* Temperature Busy Flag */
+	#define DS2438_STATUS_NVB	(1 << 5)	/* Nonvolatile Memory Busy Flag */
+	#define DS2438_STATUS_ADB	(1 << 6)	/* A/D Converter Busy Flag */
+#define DS2438_TEMP_LSB			0x01
+#define DS2438_TEMP_MSB			0x02
+#define DS2438_VOLTAGE_LSB		0x03
+#define DS2438_VOLTAGE_MSB		0x04
+#define DS2438_CURRENT_LSB		0x05
+#define DS2438_CURRENT_MSB		0x06
+#define DS2438_THRESHOLD		0x07
+
+int w1_ds2438_get_page(struct w1_slave *sl, int pageno, u8 *buf)
+{
+	unsigned int retries = W1_DS2438_RETRIES;
+	u8 w1_buf[2];
+	u8 crc;
+	size_t count;
+
+	while (retries--) {
+		crc = 0;
+
+		if (w1_reset_select_slave(sl))
+			continue;
+		w1_buf[0] = W1_DS2438_RECALL_MEMORY;
+		w1_buf[1] = 0x00;
+		w1_write_block(sl->master, w1_buf, 2);
+
+		if (w1_reset_select_slave(sl))
+			continue;
+		w1_buf[0] = W1_DS2438_READ_SCRATCH;
+		w1_buf[1] = 0x00;
+		w1_write_block(sl->master, w1_buf, 2);
+
+		count = w1_read_block(sl->master, buf, DS2438_PAGE_SIZE + 1);
+		if (count == DS2438_PAGE_SIZE + 1) {
+			crc = w1_calc_crc8(buf, DS2438_PAGE_SIZE);
+
+			/* check for correct CRC */
+			if ((u8)buf[DS2438_PAGE_SIZE] == crc)
+				return 0;
+		}
+	}
+	return -1;
+}
+
+int w1_ds2438_get_temperature(struct w1_slave *sl, int16_t *temperature)
+{
+	unsigned int retries = W1_DS2438_RETRIES;
+	u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
+	unsigned int tm = DS2438_MAX_CONVERSION_TIME;
+	unsigned long sleep_rem;
+
+	while (retries--) {
+		if (w1_reset_select_slave(sl))
+			continue;
+		w1_write_8(sl->master, W1_DS2438_CONVERT_TEMP);
+
+		mutex_unlock(&sl->master->bus_mutex);
+		sleep_rem = msleep_interruptible(tm);
+		if (sleep_rem != 0)
+			return -1;
+		if (mutex_lock_interruptible(&sl->master->bus_mutex) != 0)
+			return -1;
+
+		break;
+	}
+
+	if (w1_ds2438_get_page(sl, 0, w1_buf) == 0) {
+		*temperature = (((int16_t) w1_buf[DS2438_TEMP_MSB]) << 8) | ((uint16_t) w1_buf[DS2438_TEMP_LSB]);
+		return 0;
+	} else
+		return -1;
+}
+
+int w1_ds2438_change_config_bit(struct w1_slave *sl, u8 mask, u8 value)
+{
+	unsigned int retries = W1_DS2438_RETRIES;
+	u8 w1_buf[3];
+	u8 status;
+	int perform_write = 0;
+
+	while (retries--) {
+		if (w1_reset_select_slave(sl))
+			continue;
+		w1_buf[0] = W1_DS2438_RECALL_MEMORY;
+		w1_buf[1] = 0x00;
+		w1_write_block(sl->master, w1_buf, 2);
+
+		if (w1_reset_select_slave(sl))
+			continue;
+		w1_buf[0] = W1_DS2438_READ_SCRATCH;
+		w1_buf[1] = 0x00;
+		w1_write_block(sl->master, w1_buf, 2);
+
+		/* reading one byte of result */
+		status = w1_read_8(sl->master);
+
+		/* if bit0=1, set a value to a mask for easy compare */
+		if (value)
+			value = mask;
+
+		if ((status & mask) == value)
+			return 0;	/* already set as requested */
+		else {
+			/* changing bit */
+			status ^= mask;
+			perform_write = 1;
+		}
+		break;
+	}
+
+	if (perform_write) {
+		retries = W1_DS2438_RETRIES;
+		while (retries--) {
+			if (w1_reset_select_slave(sl))
+				continue;
+			w1_buf[0] = W1_DS2438_WRITE_SCRATCH;
+			w1_buf[1] = 0x00;
+			w1_buf[2] = status;
+			w1_write_block(sl->master, w1_buf, 3);
+
+			if (w1_reset_select_slave(sl))
+				continue;
+			w1_buf[0] = W1_DS2438_COPY_SCRATCH;
+			w1_buf[1] = 0x00;
+			w1_write_block(sl->master, w1_buf, 2);
+
+			return 0;
+		}
+	}
+	return -1;
+}
+
+uint16_t w1_ds2438_get_voltage(struct w1_slave *sl, int adc_input, uint16_t *voltage)
+{
+	unsigned int retries = W1_DS2438_RETRIES;
+	u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
+	unsigned int tm = DS2438_MAX_CONVERSION_TIME;
+	unsigned long sleep_rem;
+
+	if (w1_ds2438_change_config_bit(sl, DS2438_STATUS_AD, adc_input))
+		return -1;
+
+	while (retries--) {
+		if (w1_reset_select_slave(sl))
+			continue;
+		w1_write_8(sl->master, W1_DS2438_CONVERT_VOLTAGE);
+
+		mutex_unlock(&sl->master->bus_mutex);
+		sleep_rem = msleep_interruptible(tm);
+		if (sleep_rem != 0)
+			return -1;
+		if (mutex_lock_interruptible(&sl->master->bus_mutex) != 0)
+			return -1;
+
+		break;
+	}
+
+	if (w1_ds2438_get_page(sl, 0, w1_buf) == 0) {
+		*voltage = (((uint16_t) w1_buf[DS2438_VOLTAGE_MSB]) << 8) | ((uint16_t) w1_buf[DS2438_VOLTAGE_LSB]);
+		return 0;
+	} else
+		return -1;
+}
+
+static ssize_t iad_write(struct file *filp, struct kobject *kobj,
+			 struct bin_attribute *bin_attr, char *buf,
+			 loff_t off, size_t count)
+{
+	struct w1_slave *sl = kobj_to_w1_slave(kobj);
+	int ret;
+
+	if (count != 1 || off != 0)
+		return -EFAULT;
+
+	mutex_lock(&sl->master->bus_mutex);
+
+	if (w1_ds2438_change_config_bit(sl, DS2438_STATUS_IAD, *buf & 0x01) == 0)
+		ret = 1;
+	else
+		ret = -EIO;
+
+	mutex_unlock(&sl->master->bus_mutex);
+
+	return ret;
+}
+
+static ssize_t page0_read(struct file *filp, struct kobject *kobj,
+			  struct bin_attribute *bin_attr, char *buf,
+			  loff_t off, size_t count)
+{
+	struct w1_slave *sl = kobj_to_w1_slave(kobj);
+	int ret;
+	u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
+
+	if (off != 0)
+		return 0;
+	if (!buf)
+		return -EINVAL;
+
+	mutex_lock(&sl->master->bus_mutex);
+
+	if (w1_ds2438_get_page(sl, 0, w1_buf) == 0) {
+		memcpy(buf, &w1_buf, DS2438_PAGE_SIZE);
+		ret = DS2438_PAGE_SIZE;
+	} else
+		ret = -EIO;
+
+	mutex_unlock(&sl->master->bus_mutex);
+
+	return ret;
+}
+
+static ssize_t temperature_read(struct file *filp, struct kobject *kobj,
+				struct bin_attribute *bin_attr, char *buf,
+				loff_t off, size_t count)
+{
+	struct w1_slave *sl = kobj_to_w1_slave(kobj);
+	int ret;
+	ssize_t c = PAGE_SIZE;
+	int16_t temp;
+
+	if (off != 0)
+		return 0;
+	if (!buf)
+		return -EINVAL;
+
+	mutex_lock(&sl->master->bus_mutex);
+
+	if (w1_ds2438_get_temperature(sl, &temp) == 0) {
+		c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", temp);
+		ret = PAGE_SIZE - c;
+	} else
+		ret = -EIO;
+
+	mutex_unlock(&sl->master->bus_mutex);
+
+	return ret;
+}
+
+static ssize_t vad_read(struct file *filp, struct kobject *kobj,
+			struct bin_attribute *bin_attr, char *buf,
+			loff_t off, size_t count)
+{
+	struct w1_slave *sl = kobj_to_w1_slave(kobj);
+	int ret;
+	ssize_t c = PAGE_SIZE;
+	uint16_t voltage;
+
+	if (off != 0)
+		return 0;
+	if (!buf)
+		return -EINVAL;
+
+	mutex_lock(&sl->master->bus_mutex);
+
+	if (w1_ds2438_get_voltage(sl, DS2438_ADC_INPUT_VAD, &voltage) == 0) {
+		c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", voltage);
+		ret = PAGE_SIZE - c;
+	} else
+		ret = -EIO;
+
+	mutex_unlock(&sl->master->bus_mutex);
+
+	return ret;
+}
+
+static ssize_t vdd_read(struct file *filp, struct kobject *kobj,
+			struct bin_attribute *bin_attr, char *buf,
+			loff_t off, size_t count)
+{
+	struct w1_slave *sl = kobj_to_w1_slave(kobj);
+	int ret;
+	ssize_t c = PAGE_SIZE;
+	uint16_t voltage;
+
+	if (off != 0)
+		return 0;
+	if (!buf)
+		return -EINVAL;
+
+	mutex_lock(&sl->master->bus_mutex);
+
+	if (w1_ds2438_get_voltage(sl, DS2438_ADC_INPUT_VDD, &voltage) == 0) {
+		c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", voltage);
+		ret = PAGE_SIZE - c;
+	} else
+		ret = -EIO;
+
+	mutex_unlock(&sl->master->bus_mutex);
+
+	return ret;
+}
+
+static BIN_ATTR(iad, S_IRUGO | S_IWUSR | S_IWGRP, NULL, iad_write, 1);
+static BIN_ATTR_RO(page0, DS2438_PAGE_SIZE);
+static BIN_ATTR_RO(temperature, 0/* real length varies */);
+static BIN_ATTR_RO(vad, 0/* real length varies */);
+static BIN_ATTR_RO(vdd, 0/* real length varies */);
+
+static struct bin_attribute *w1_ds2438_bin_attrs[] = {
+	&bin_attr_iad,
+	&bin_attr_page0,
+	&bin_attr_temperature,
+	&bin_attr_vad,
+	&bin_attr_vdd,
+	NULL,
+};
+
+static const struct attribute_group w1_ds2438_group = {
+	.bin_attrs = w1_ds2438_bin_attrs,
+};
+
+static const struct attribute_group *w1_ds2438_groups[] = {
+	&w1_ds2438_group,
+	NULL,
+};
+
+static struct w1_family_ops w1_ds2438_fops = {
+	.groups		= w1_ds2438_groups,
+};
+
+static struct w1_family w1_ds2438_family = {
+	.fid = W1_FAMILY_DS2438,
+	.fops = &w1_ds2438_fops,
+};
+module_w1_family(w1_ds2438_family);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mariusz Bialonczyk <manio@skyboo.net>");
+MODULE_DESCRIPTION("1-wire driver for Maxim/Dallas DS2438 Smart Battery Monitor");
+MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2438));
diff --git a/drivers/w1/w1_family.h b/drivers/w1/w1_family.h
index 10a7a076..627c90a 100644
--- a/drivers/w1/w1_family.h
+++ b/drivers/w1/w1_family.h
@@ -35,6 +35,7 @@
 #define W1_COUNTER_DS2423	0x1D
 #define W1_THERM_DS1822  	0x22
 #define W1_EEPROM_DS2433  	0x23
+#define W1_FAMILY_DS2438	0x26
 #define W1_THERM_DS18B20 	0x28
 #define W1_FAMILY_DS2408	0x29
 #define W1_EEPROM_DS2431	0x2D
-- 
2.9.3

[PATCH 4/4] w1: add documentation for w1_ds2438

[Mariusz Bialonczyk]

Signed-off-by: Mariusz Bialonczyk <manio@skyboo.net>
---
 Documentation/w1/slaves/00-INDEX  |  2 ++
 Documentation/w1/slaves/w1_ds2438 | 63 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+)
 create mode 100644 Documentation/w1/slaves/w1_ds2438

diff --git a/Documentation/w1/slaves/00-INDEX b/Documentation/w1/slaves/00-INDEX
index cbcca1d..8d76718 100644
--- a/Documentation/w1/slaves/00-INDEX
+++ b/Documentation/w1/slaves/00-INDEX
@@ -6,5 +6,7 @@ w1_ds2413
 	- The Maxim/Dallas Semiconductor ds2413 dual channel addressable switch.
 w1_ds2423
 	- The Maxim/Dallas Semiconductor ds2423 counter device.
+w1_ds2438
+	- The Maxim/Dallas Semiconductor ds2438 smart battery monitor.
 w1_ds28e04
 	- The Maxim/Dallas Semiconductor ds28e04 eeprom.
diff --git a/Documentation/w1/slaves/w1_ds2438 b/Documentation/w1/slaves/w1_ds2438
new file mode 100644
index 0000000..b99f367
--- /dev/null
+++ b/Documentation/w1/slaves/w1_ds2438
@@ -0,0 +1,63 @@
+Kernel driver w1_ds2438
+=======================
+
+Supported chips:
+  * Maxim DS2438 Smart Battery Monitor
+
+supported family codes:
+        W1_FAMILY_DS2438        0x26
+
+Author: Mariusz Bialonczyk <manio@skyboo.net>
+
+Description
+-----------
+
+The DS2438 chip provides several functions that are desirable to carry in
+a battery pack. It also has a 40 bytes of nonvolatile EEPROM.
+Because the ability of temperature, current and voltage measurement, the chip
+is also often used in weather stations and applications such as: rain gauge,
+wind speed/direction measuring, humidity sensing, etc.
+
+Current support is provided through the following sysfs files (all files
+except "iad" are readonly):
+
+"iad"
+-----
+This file controls the 'Current A/D Control Bit' (IAD) in the
+Status/Configuration Register.
+Writing a zero value will clear the IAD bit and disables the current
+measurements.
+Writing value "1" is setting the IAD bit (enables the measurements).
+The IAD bit is enabled by default in the DS2438.
+
+When writing to sysfs file bits 2-7 are ignored, so it's safe to write ASCII.
+An I/O error is returned when there is a problem setting the new value.
+
+"page0"
+-------
+This file provides full 8 bytes of the chip Page 0 (00h).
+This page contains the most frequently accessed information of the DS2438.
+Internally when this file is read, the additional CRC byte is also obtained
+from the slave device. If it is correct, the 8 bytes page data are passed
+to userspace, otherwise an I/O error is returned.
+
+"temperature"
+-------------
+Opening and reading this file initiates the CONVERT_T (temperature conversion)
+command of the chip, afterwards the temperature is read from the device
+registers and provided as an ASCII decimal value.
+
+Important: The returned value has to be divided by 256 to get a real
+temperature in degrees Celsius.
+
+"vad", "vdd"
+------------
+Opening and reading this file initiates the CONVERT_V (voltage conversion)
+command of the chip.
+
+Depending on a sysfs filename a different input for the A/D will be selected:
+vad: general purpose A/D input (VAD)
+vdd: battery input (VDD)
+
+After the voltage conversion the value is returned as decimal ASCII.
+Note: The value is in mV, so to get a volts the value has to be divided by 10.
-- 
2.9.3

Re: [PATCH 1/4] Documentation: w1_therm: clearly state about binary value for precision

[Mariusz Bialonczyk]

On Thu, 16 Feb 2017 10:05:36 +0100
Mariusz Bialonczyk <manio@skyboo.net> wrote:

> Signed-off-by: Mariusz Bialonczyk <manio@skyboo.net>
> ---
>  Documentation/w1/slaves/w1_therm | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/Documentation/w1/slaves/w1_therm b/Documentation/w1/slaves/w1_therm
> index d1f93af..e10cd91 100644
> --- a/Documentation/w1/slaves/w1_therm
> +++ b/Documentation/w1/slaves/w1_therm
> @@ -42,6 +42,7 @@ SRAM, so it is reset when the sensor gets power-cycled.
>  To store the current precision configuration into EEPROM, the value 0
>  has to be written to the sysfs w1_slave file. Since the EEPROM has a limited
>  amount of writes (>50k), this command should be used wisely.
> +Note: this precision value has to be a binary one-byte value, not ASCII.
>  
>  The module parameter strong_pullup can be set to 0 to disable the
>  strong pullup, 1 to enable autodetection or 2 to force strong pullup.
> -- 
> 2.9.3
> 

Please skip this single patch. I was wrong about it.
w1_slave_store is using kstrtoint() so it is currently ok.

regards,
-- 
Mariusz Białończyk | xmpp/e-mail: manio@skyboo.net
http://manio.skyboo.net | https://github.com/manio