diff options
Diffstat (limited to 'drivers/hwmon/sht15.c')
| -rw-r--r-- | drivers/hwmon/sht15.c | 692 |
1 files changed, 692 insertions, 0 deletions
diff --git a/drivers/hwmon/sht15.c b/drivers/hwmon/sht15.c new file mode 100644 index 0000000..6cbdc2f --- /dev/null +++ b/drivers/hwmon/sht15.c @@ -0,0 +1,692 @@ +/* + * 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"); |
