--- /dev/null
+/*
+ * 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));
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