w1: add support for DS2438 Smart Battery Monitor

Detailed information about support and provided sysfs files
in my next commit which creates a documentation file:
Documentation/w1/slaves/w1_ds2438
Signed-off-by: NMariusz Bialonczyk <manio@skyboo.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/w1/slaves/Kconfig

@@ -86,6 +86,12 @@ 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

drivers/w1/slaves/Makefile

@@ -11,6 +11,7 @@ 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

drivers/w1/slaves/w1_ds2438.c

+/*
+ * 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;
+	int ret;
+
+	mutex_lock(&sl->master->bus_mutex);
+
+	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) {
+			ret = -1;
+			goto post_unlock;
+		}
+
+		if (mutex_lock_interruptible(&sl->master->bus_mutex) != 0) {
+			ret = -1;
+			goto post_unlock;
+		}
+
+		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]);
+		ret = 0;
+	} else
+		ret = -1;
+
+	mutex_unlock(&sl->master->bus_mutex);
+
+post_unlock:
+	return ret;
+}
+
+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;
+	int ret;
+
+	mutex_lock(&sl->master->bus_mutex);
+
+	if (w1_ds2438_change_config_bit(sl, DS2438_STATUS_AD, adc_input)) {
+		ret = -1;
+		goto pre_unlock;
+	}
+
+	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) {
+			ret = -1;
+			goto post_unlock;
+		}
+
+		if (mutex_lock_interruptible(&sl->master->bus_mutex) != 0) {
+			ret = -1;
+			goto post_unlock;
+		}
+
+		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]);
+		ret = 0;
+	} else
+		ret = -1;
+
+pre_unlock:
+	mutex_unlock(&sl->master->bus_mutex);
+
+post_unlock:
+	return ret;
+}
+
+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;
+
+	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;
+
+	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;
+
+	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;
+
+	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;
+
+	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;
+
+	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));

drivers/w1/w1_family.h

@@ -29,6 +29,7 @@
 #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