--- /dev/null
+/*
+ * sht15.c - support for the SHT15 Temperature and Humidity Sensor
+ *
+ * Copyright (c) 2009 Jonathan Cameron
+ *
+ * Copyright (c) 2007 Wouter Horre
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Currently ignoring checksum on readings.
+ * Default resolution only (14bit temp, 12bit humidity)
+ * Ignoring battery status.
+ * Heater not enabled.
+ * Timings are all conservative.
+ *
+ * Data sheet available (1/2009) at
+ * http://www.sensirion.ch/en/pdf/product_information/Datasheet-humidity-sensor-SHT1x.pdf
+ *
+ * Regulator supply name = vcc
+ */
+
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/gpio.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/jiffies.h>
+#include <linux/err.h>
+#include <linux/sht15.h>
+#include <linux/regulator/consumer.h>
+#include <asm/atomic.h>
+
+#define SHT15_MEASURE_TEMP 3
+#define SHT15_MEASURE_RH 5
+
+#define SHT15_READING_NOTHING 0
+#define SHT15_READING_TEMP 1
+#define SHT15_READING_HUMID 2
+
+/* Min timings in nsecs */
+#define SHT15_TSCKL 100 /* clock low */
+#define SHT15_TSCKH 100 /* clock high */
+#define SHT15_TSU 150 /* data setup time */
+
+/**
+ * struct sht15_temppair - elements of voltage dependant temp calc
+ * @vdd: supply voltage in microvolts
+ * @d1: see data sheet
+ */
+struct sht15_temppair {
+ int vdd; /* microvolts */
+ int d1;
+};
+
+/* Table 9 from data sheet - relates temperature calculation
+ * to supply voltage.
+ */
+static const struct sht15_temppair temppoints[] = {
+ { 2500000, -39400 },
+ { 3000000, -39600 },
+ { 3500000, -39700 },
+ { 4000000, -39800 },
+ { 5000000, -40100 },
+};
+
+/**
+ * struct sht15_data - device instance specific data
+ * @pdata: platform data (gpio's etc)
+ * @read_work: bh of interrupt handler
+ * @wait_queue: wait queue for getting values from device
+ * @val_temp: last temperature value read from device
+ * @val_humid: last humidity value read from device
+ * @flag: status flag used to identify what the last request was
+ * @valid: are the current stored values valid (start condition)
+ * @last_updat: time of last update
+ * @read_lock: mutex to ensure only one read in progress
+ * at a time.
+ * @dev: associate device structure
+ * @hwmon_dev: device associated with hwmon subsystem
+ * @reg: associated regulator (if specified)
+ * @nb: notifier block to handle notifications of voltage changes
+ * @supply_uV: local copy of supply voltage used to allow
+ * use of regulator consumer if available
+ * @supply_uV_valid: indicates that an updated value has not yet
+ * been obtained from the regulator and so any calculations
+ * based upon it will be invalid.
+ * @update_supply_work: work struct that is used to update the supply_uV
+ * @interrupt_handled: flag used to indicate a hander has been scheduled
+ */
+struct sht15_data {
+ struct sht15_platform_data *pdata;
+ struct work_struct read_work;
+ wait_queue_head_t wait_queue;
+ uint16_t val_temp;
+ uint16_t val_humid;
+ u8 flag;
+ u8 valid;
+ unsigned long last_updat;
+ struct mutex read_lock;
+ struct device *dev;
+ struct device *hwmon_dev;
+ struct regulator *reg;
+ struct notifier_block nb;
+ int supply_uV;
+ int supply_uV_valid;
+ struct work_struct update_supply_work;
+ atomic_t interrupt_handled;
+};
+
+/**
+ * sht15_connection_reset() - reset the comms interface
+ * @data: sht15 specific data
+ *
+ * This implements section 3.4 of the data sheet
+ */
+static void sht15_connection_reset(struct sht15_data *data)
+{
+ int i;
+ gpio_direction_output(data->pdata->gpio_data, 1);
+ ndelay(SHT15_TSCKL);
+ gpio_set_value(data->pdata->gpio_sck, 0);
+ ndelay(SHT15_TSCKL);
+ for (i = 0; i < 9; ++i) {
+ gpio_set_value(data->pdata->gpio_sck, 1);
+ ndelay(SHT15_TSCKH);
+ gpio_set_value(data->pdata->gpio_sck, 0);
+ ndelay(SHT15_TSCKL);
+ }
+}
+/**
+ * sht15_send_bit() - send an individual bit to the device
+ * @data: device state data
+ * @val: value of bit to be sent
+ **/
+static inline void sht15_send_bit(struct sht15_data *data, int val)
+{
+
+ gpio_set_value(data->pdata->gpio_data, val);
+ ndelay(SHT15_TSU);
+ gpio_set_value(data->pdata->gpio_sck, 1);
+ ndelay(SHT15_TSCKH);
+ gpio_set_value(data->pdata->gpio_sck, 0);
+ ndelay(SHT15_TSCKL); /* clock low time */
+}
+
+/**
+ * sht15_transmission_start() - specific sequence for new transmission
+ *
+ * @data: device state data
+ * Timings for this are not documented on the data sheet, so very
+ * conservative ones used in implementation. This implements
+ * figure 12 on the data sheet.
+ **/
+static void sht15_transmission_start(struct sht15_data *data)
+{
+ /* ensure data is high and output */
+ gpio_direction_output(data->pdata->gpio_data, 1);
+ ndelay(SHT15_TSU);
+ gpio_set_value(data->pdata->gpio_sck, 0);
+ ndelay(SHT15_TSCKL);
+ gpio_set_value(data->pdata->gpio_sck, 1);
+ ndelay(SHT15_TSCKH);
+ gpio_set_value(data->pdata->gpio_data, 0);
+ ndelay(SHT15_TSU);
+ gpio_set_value(data->pdata->gpio_sck, 0);
+ ndelay(SHT15_TSCKL);
+ gpio_set_value(data->pdata->gpio_sck, 1);
+ ndelay(SHT15_TSCKH);
+ gpio_set_value(data->pdata->gpio_data, 1);
+ ndelay(SHT15_TSU);
+ gpio_set_value(data->pdata->gpio_sck, 0);
+ ndelay(SHT15_TSCKL);
+}
+/**
+ * sht15_send_byte() - send a single byte to the device
+ * @data: device state
+ * @byte: value to be sent
+ **/
+static void sht15_send_byte(struct sht15_data *data, u8 byte)
+{
+ int i;
+ for (i = 0; i < 8; i++) {
+ sht15_send_bit(data, !!(byte & 0x80));
+ byte <<= 1;
+ }
+}
+/**
+ * sht15_wait_for_response() - checks for ack from device
+ * @data: device state
+ **/
+static int sht15_wait_for_response(struct sht15_data *data)
+{
+ gpio_direction_input(data->pdata->gpio_data);
+ gpio_set_value(data->pdata->gpio_sck, 1);
+ ndelay(SHT15_TSCKH);
+ if (gpio_get_value(data->pdata->gpio_data)) {
+ gpio_set_value(data->pdata->gpio_sck, 0);
+ dev_err(data->dev, "Command not acknowledged\n");
+ sht15_connection_reset(data);
+ return -EIO;
+ }
+ gpio_set_value(data->pdata->gpio_sck, 0);
+ ndelay(SHT15_TSCKL);
+ return 0;
+}
+
+/**
+ * sht15_send_cmd() - Sends a command to the device.
+ * @data: device state
+ * @cmd: command byte to be sent
+ *
+ * On entry, sck is output low, data is output pull high
+ * and the interrupt disabled.
+ **/
+static int sht15_send_cmd(struct sht15_data *data, u8 cmd)
+{
+ int ret = 0;
+ sht15_transmission_start(data);
+ sht15_send_byte(data, cmd);
+ ret = sht15_wait_for_response(data);
+ return ret;
+}
+/**
+ * sht15_update_single_val() - get a new value from device
+ * @data: device instance specific data
+ * @command: command sent to request value
+ * @timeout_msecs: timeout after which comms are assumed
+ * to have failed are reset.
+ **/
+static inline int sht15_update_single_val(struct sht15_data *data,
+ int command,
+ int timeout_msecs)
+{
+ int ret;
+ ret = sht15_send_cmd(data, command);
+ if (ret)
+ return ret;
+
+ gpio_direction_input(data->pdata->gpio_data);
+ atomic_set(&data->interrupt_handled, 0);
+
+ enable_irq(gpio_to_irq(data->pdata->gpio_data));
+ if (gpio_get_value(data->pdata->gpio_data) == 0) {
+ disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data));
+ /* Only relevant if the interrupt hasn't occured. */
+ if (!atomic_read(&data->interrupt_handled))
+ schedule_work(&data->read_work);
+ }
+ ret = wait_event_timeout(data->wait_queue,
+ (data->flag == SHT15_READING_NOTHING),
+ msecs_to_jiffies(timeout_msecs));
+ if (ret == 0) {/* timeout occurred */
+ disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data));;
+ sht15_connection_reset(data);
+ return -ETIME;
+ }
+ return 0;
+}
+
+/**
+ * sht15_update_vals() - get updated readings from device if too old
+ * @data: device state
+ **/
+static int sht15_update_vals(struct sht15_data *data)
+{
+ int ret = 0;
+ int timeout = HZ;
+
+ mutex_lock(&data->read_lock);
+ if (time_after(jiffies, data->last_updat + timeout)
+ || !data->valid) {
+ data->flag = SHT15_READING_HUMID;
+ ret = sht15_update_single_val(data, SHT15_MEASURE_RH, 160);
+ if (ret)
+ goto error_ret;
+ data->flag = SHT15_READING_TEMP;
+ ret = sht15_update_single_val(data, SHT15_MEASURE_TEMP, 400);
+ if (ret)
+ goto error_ret;
+ data->valid = 1;
+ data->last_updat = jiffies;
+ }
+error_ret:
+ mutex_unlock(&data->read_lock);
+
+ return ret;
+}
+
+/**
+ * sht15_calc_temp() - convert the raw reading to a temperature
+ * @data: device state
+ *
+ * As per section 4.3 of the data sheet.
+ **/
+static inline int sht15_calc_temp(struct sht15_data *data)
+{
+ int d1 = 0;
+ int i;
+
+ for (i = 1; i < ARRAY_SIZE(temppoints) - 1; i++)
+ /* Find pointer to interpolate */
+ if (data->supply_uV > temppoints[i - 1].vdd) {
+ d1 = (data->supply_uV/1000 - temppoints[i - 1].vdd)
+ * (temppoints[i].d1 - temppoints[i - 1].d1)
+ / (temppoints[i].vdd - temppoints[i - 1].vdd)
+ + temppoints[i - 1].d1;
+ break;
+ }
+
+ return data->val_temp*10 + d1;
+}
+
+/**
+ * sht15_calc_humid() - using last temperature convert raw to humid
+ * @data: device state
+ *
+ * This is the temperature compensated version as per section 4.2 of
+ * the data sheet.
+ **/
+static inline int sht15_calc_humid(struct sht15_data *data)
+{
+ int RHlinear; /* milli percent */
+ int temp = sht15_calc_temp(data);
+
+ const int c1 = -4;
+ const int c2 = 40500; /* x 10 ^ -6 */
+ const int c3 = 2800; /* x10 ^ -9 */
+
+ RHlinear = c1*1000
+ + c2 * data->val_humid/1000
+ + (data->val_humid * data->val_humid * c3)/1000000;
+ return (temp - 25000) * (10000 + 800 * data->val_humid)
+ / 1000000 + RHlinear;
+}
+
+static ssize_t sht15_show_temp(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int ret;
+ struct sht15_data *data = dev_get_drvdata(dev);
+
+ /* Technically no need to read humidity as well */
+ ret = sht15_update_vals(data);
+
+ return ret ? ret : sprintf(buf, "%d\n",
+ sht15_calc_temp(data));
+}
+
+static ssize_t sht15_show_humidity(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int ret;
+ struct sht15_data *data = dev_get_drvdata(dev);
+
+ ret = sht15_update_vals(data);
+
+ return ret ? ret : sprintf(buf, "%d\n", sht15_calc_humid(data));
+
+};
+static ssize_t show_name(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ return sprintf(buf, "%s\n", pdev->name);
+}
+
+static SENSOR_DEVICE_ATTR(temp1_input,
+ S_IRUGO, sht15_show_temp,
+ NULL, 0);
+static SENSOR_DEVICE_ATTR(humidity1_input,
+ S_IRUGO, sht15_show_humidity,
+ NULL, 0);
+static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
+static struct attribute *sht15_attrs[] = {
+ &sensor_dev_attr_temp1_input.dev_attr.attr,
+ &sensor_dev_attr_humidity1_input.dev_attr.attr,
+ &dev_attr_name.attr,
+ NULL,
+};
+
+static const struct attribute_group sht15_attr_group = {
+ .attrs = sht15_attrs,
+};
+
+static irqreturn_t sht15_interrupt_fired(int irq, void *d)
+{
+ struct sht15_data *data = d;
+ /* First disable the interrupt */
+ disable_irq_nosync(irq);
+ atomic_inc(&data->interrupt_handled);
+ /* Then schedule a reading work struct */
+ if (data->flag != SHT15_READING_NOTHING)
+ schedule_work(&data->read_work);
+ return IRQ_HANDLED;
+}
+
+/* Each byte of data is acknowledged by pulling the data line
+ * low for one clock pulse.
+ */
+static void sht15_ack(struct sht15_data *data)
+{
+ gpio_direction_output(data->pdata->gpio_data, 0);
+ ndelay(SHT15_TSU);
+ gpio_set_value(data->pdata->gpio_sck, 1);
+ ndelay(SHT15_TSU);
+ gpio_set_value(data->pdata->gpio_sck, 0);
+ ndelay(SHT15_TSU);
+ gpio_set_value(data->pdata->gpio_data, 1);
+
+ gpio_direction_input(data->pdata->gpio_data);
+}
+/**
+ * sht15_end_transmission() - notify device of end of transmission
+ * @data: device state
+ *
+ * This is basically a NAK. (single clock pulse, data high)
+ **/
+static void sht15_end_transmission(struct sht15_data *data)
+{
+ gpio_direction_output(data->pdata->gpio_data, 1);
+ ndelay(SHT15_TSU);
+ gpio_set_value(data->pdata->gpio_sck, 1);
+ ndelay(SHT15_TSCKH);
+ gpio_set_value(data->pdata->gpio_sck, 0);
+ ndelay(SHT15_TSCKL);
+}
+
+static void sht15_bh_read_data(struct work_struct *work_s)
+{
+ int i;
+ uint16_t val = 0;
+ struct sht15_data *data
+ = container_of(work_s, struct sht15_data,
+ read_work);
+ /* Firstly, verify the line is low */
+ if (gpio_get_value(data->pdata->gpio_data)) {
+ /* If not, then start the interrupt again - care
+ here as could have gone low in meantime so verify
+ it hasn't!
+ */
+ atomic_set(&data->interrupt_handled, 0);
+ enable_irq(gpio_to_irq(data->pdata->gpio_data));
+ /* If still not occured or another handler has been scheduled */
+ if (gpio_get_value(data->pdata->gpio_data)
+ || atomic_read(&data->interrupt_handled))
+ return;
+ }
+ /* Read the data back from the device */
+ for (i = 0; i < 16; ++i) {
+ val <<= 1;
+ gpio_set_value(data->pdata->gpio_sck, 1);
+ ndelay(SHT15_TSCKH);
+ val |= !!gpio_get_value(data->pdata->gpio_data);
+ gpio_set_value(data->pdata->gpio_sck, 0);
+ ndelay(SHT15_TSCKL);
+ if (i == 7)
+ sht15_ack(data);
+ }
+ /* Tell the device we are done */
+ sht15_end_transmission(data);
+
+ switch (data->flag) {
+ case SHT15_READING_TEMP:
+ data->val_temp = val;
+ break;
+ case SHT15_READING_HUMID:
+ data->val_humid = val;
+ break;
+ }
+
+ data->flag = SHT15_READING_NOTHING;
+ wake_up(&data->wait_queue);
+}
+
+static void sht15_update_voltage(struct work_struct *work_s)
+{
+ struct sht15_data *data
+ = container_of(work_s, struct sht15_data,
+ update_supply_work);
+ data->supply_uV = regulator_get_voltage(data->reg);
+}
+
+/**
+ * sht15_invalidate_voltage() - mark supply voltage invalid when notified by reg
+ * @nb: associated notification structure
+ * @event: voltage regulator state change event code
+ * @ignored: function parameter - ignored here
+ *
+ * Note that as the notification code holds the regulator lock, we have
+ * to schedule an update of the supply voltage rather than getting it directly.
+ **/
+static int sht15_invalidate_voltage(struct notifier_block *nb,
+ unsigned long event,
+ void *ignored)
+{
+ struct sht15_data *data = container_of(nb, struct sht15_data, nb);
+
+ if (event == REGULATOR_EVENT_VOLTAGE_CHANGE)
+ data->supply_uV_valid = false;
+ schedule_work(&data->update_supply_work);
+
+ return NOTIFY_OK;
+}
+
+static int __devinit sht15_probe(struct platform_device *pdev)
+{
+ int ret = 0;
+ struct sht15_data *data = kzalloc(sizeof(*data), GFP_KERNEL);
+
+ if (!data) {
+ ret = -ENOMEM;
+ dev_err(&pdev->dev, "kzalloc failed");
+ goto error_ret;
+ }
+
+ INIT_WORK(&data->read_work, sht15_bh_read_data);
+ INIT_WORK(&data->update_supply_work, sht15_update_voltage);
+ platform_set_drvdata(pdev, data);
+ mutex_init(&data->read_lock);
+ data->dev = &pdev->dev;
+ init_waitqueue_head(&data->wait_queue);
+
+ if (pdev->dev.platform_data == NULL) {
+ dev_err(&pdev->dev, "no platform data supplied");
+ goto err_free_data;
+ }
+ data->pdata = pdev->dev.platform_data;
+ data->supply_uV = data->pdata->supply_mv*1000;
+
+/* If a regulator is available, query what the supply voltage actually is!*/
+ data->reg = regulator_get(data->dev, "vcc");
+ if (!IS_ERR(data->reg)) {
+ data->supply_uV = regulator_get_voltage(data->reg);
+ regulator_enable(data->reg);
+ /* setup a notifier block to update this if another device
+ * causes the voltage to change */
+ data->nb.notifier_call = &sht15_invalidate_voltage;
+ ret = regulator_register_notifier(data->reg, &data->nb);
+ }
+/* Try requesting the GPIOs */
+ ret = gpio_request(data->pdata->gpio_sck, "SHT15 sck");
+ if (ret) {
+ dev_err(&pdev->dev, "gpio request failed");
+ goto err_free_data;
+ }
+ gpio_direction_output(data->pdata->gpio_sck, 0);
+ ret = gpio_request(data->pdata->gpio_data, "SHT15 data");
+ if (ret) {
+ dev_err(&pdev->dev, "gpio request failed");
+ goto err_release_gpio_sck;
+ }
+ ret = sysfs_create_group(&pdev->dev.kobj, &sht15_attr_group);
+ if (ret) {
+ dev_err(&pdev->dev, "sysfs create failed");
+ goto err_free_data;
+ }
+
+ ret = request_irq(gpio_to_irq(data->pdata->gpio_data),
+ sht15_interrupt_fired,
+ IRQF_TRIGGER_FALLING,
+ "sht15 data",
+ data);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to get irq for data line");
+ goto err_release_gpio_data;
+ }
+ disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data));
+ sht15_connection_reset(data);
+ sht15_send_cmd(data, 0x1E);
+
+ data->hwmon_dev = hwmon_device_register(data->dev);
+ if (IS_ERR(data->hwmon_dev)) {
+ ret = PTR_ERR(data->hwmon_dev);
+ goto err_release_gpio_data;
+ }
+ return 0;
+
+err_release_gpio_data:
+ gpio_free(data->pdata->gpio_data);
+err_release_gpio_sck:
+ gpio_free(data->pdata->gpio_sck);
+err_free_data:
+ kfree(data);
+error_ret:
+
+ return ret;
+}
+
+static int __devexit sht15_remove(struct platform_device *pdev)
+{
+ struct sht15_data *data = platform_get_drvdata(pdev);
+
+ /* Make sure any reads from the device are done and
+ * prevent new ones beginnning */
+ mutex_lock(&data->read_lock);
+ hwmon_device_unregister(data->hwmon_dev);
+ sysfs_remove_group(&pdev->dev.kobj, &sht15_attr_group);
+ if (!IS_ERR(data->reg)) {
+ regulator_unregister_notifier(data->reg, &data->nb);
+ regulator_disable(data->reg);
+ regulator_put(data->reg);
+ }
+
+ free_irq(gpio_to_irq(data->pdata->gpio_data), data);
+ gpio_free(data->pdata->gpio_data);
+ gpio_free(data->pdata->gpio_sck);
+ mutex_unlock(&data->read_lock);
+ kfree(data);
+ return 0;
+}
+
+
+static struct platform_driver sht_drivers[] = {
+ {
+ .driver = {
+ .name = "sht10",
+ .owner = THIS_MODULE,
+ },
+ .probe = sht15_probe,
+ .remove = sht15_remove,
+ }, {
+ .driver = {
+ .name = "sht11",
+ .owner = THIS_MODULE,
+ },
+ .probe = sht15_probe,
+ .remove = sht15_remove,
+ }, {
+ .driver = {
+ .name = "sht15",
+ .owner = THIS_MODULE,
+ },
+ .probe = sht15_probe,
+ .remove = sht15_remove,
+ }, {
+ .driver = {
+ .name = "sht71",
+ .owner = THIS_MODULE,
+ },
+ .probe = sht15_probe,
+ .remove = sht15_remove,
+ }, {
+ .driver = {
+ .name = "sht75",
+ .owner = THIS_MODULE,
+ },
+ .probe = sht15_probe,
+ .remove = sht15_remove,
+ },
+};
+
+
+static int __init sht15_init(void)
+{
+ int ret;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(sht_drivers); i++) {
+ ret = platform_driver_register(&sht_drivers[i]);
+ if (ret)
+ goto error_unreg;
+ }
+
+ return 0;
+
+error_unreg:
+ while (--i >= 0)
+ platform_driver_unregister(&sht_drivers[i]);
+
+ return ret;
+}
+module_init(sht15_init);
+
+static void __exit sht15_exit(void)
+{
+ int i;
+ for (i = ARRAY_SIZE(sht_drivers) - 1; i >= 0; i--)
+ platform_driver_unregister(&sht_drivers[i]);
+}
+module_exit(sht15_exit);
+
+MODULE_LICENSE("GPL");
projects / linux-platform-drivers-x86.git / commitdiff