iio: Add AS3935 lightning sensor support

AS3935 chipset can detect lightning strikes and reports those back as
events and the estimated distance to the storm.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

5 files changed, 483 insertions, 0 deletions

diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 5dd0e120a504..743485e4d6f8 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -74,6 +74,7 @@ if IIO_TRIGGER
    source "drivers/iio/trigger/Kconfig"
 endif #IIO_TRIGGER
 source "drivers/iio/pressure/Kconfig"
+source "drivers/iio/proximity/Kconfig"
 source "drivers/iio/temperature/Kconfig"
 
 endif # IIO
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 887d39090d75..698afc2d17ce 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -24,5 +24,6 @@ obj-y += light/
 obj-y += magnetometer/
 obj-y += orientation/
 obj-y += pressure/
+obj-y += proximity/
 obj-y += temperature/
 obj-y += trigger/
diff --git a/drivers/iio/proximity/Kconfig b/drivers/iio/proximity/Kconfig
new file mode 100644
index 000000000000..0c8cdf58f6a1
--- /dev/null
+++ b/drivers/iio/proximity/Kconfig
@@ -0,0 +1,19 @@
+#
+# Proximity sensors
+#
+
+menu "Lightning sensors"
+
+config AS3935
+        tristate "AS3935 Franklin lightning sensor"
+        select IIO_BUFFER
+        select IIO_TRIGGERED_BUFFER
+        depends on SPI
+        help
+          Say Y here to build SPI interface support for the Austrian
+          Microsystems AS3935 lightning detection sensor.
+
+          To compile this driver as a module, choose M here: the
+          module will be called as3935
+
+endmenu
diff --git a/drivers/iio/proximity/Makefile b/drivers/iio/proximity/Makefile
new file mode 100644
index 000000000000..743adee1c8bf
--- /dev/null
+++ b/drivers/iio/proximity/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for IIO proximity sensors
+#
+
+# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_AS3935)            += as3935.o
diff --git a/drivers/iio/proximity/as3935.c b/drivers/iio/proximity/as3935.c
new file mode 100644
index 000000000000..bf677bfe8eb2
--- /dev/null
+++ b/drivers/iio/proximity/as3935.c
@@ -0,0 +1,456 @@
+/*
+ * as3935.c - Support for AS3935 Franklin lightning sensor
+ *
+ * Copyright (C) 2014 Matt Ranostay <mranostay@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/workqueue.h>
+#include <linux/mutex.h>
+#include <linux/err.h>
+#include <linux/irq.h>
+#include <linux/gpio.h>
+#include <linux/spi/spi.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/of_gpio.h>
+
+
+#define AS3935_AFE_GAIN         0x00
+#define AS3935_AFE_MASK         0x3F
+#define AS3935_AFE_GAIN_MAX     0x1F
+#define AS3935_AFE_PWR_BIT      BIT(0)
+
+#define AS3935_INT              0x03
+#define AS3935_INT_MASK         0x07
+#define AS3935_EVENT_INT        BIT(3)
+#define AS3935_NOISE_INT        BIT(1)
+
+#define AS3935_DATA             0x07
+#define AS3935_DATA_MASK        0x3F
+
+#define AS3935_TUNE_CAP         0x08
+#define AS3935_CALIBRATE        0x3D
+
+#define AS3935_WRITE_DATA       BIT(15)
+#define AS3935_READ_DATA        BIT(14)
+#define AS3935_ADDRESS(x)       ((x) << 8)
+
+#define MAX_PF_CAP              120
+#define TUNE_CAP_DIV            8
+
+struct as3935_state {
+        struct spi_device *spi;
+        struct iio_trigger *trig;
+        struct mutex lock;
+        struct delayed_work work;
+
+        u32 tune_cap;
+        u8 buf[2] ____cacheline_aligned;
+};
+
+static const struct iio_chan_spec as3935_channels[] = {
+        {
+                .type           = IIO_PROXIMITY,
+                .info_mask_separate =
+                        BIT(IIO_CHAN_INFO_RAW) |
+                        BIT(IIO_CHAN_INFO_PROCESSED),
+                .scan_index     = 0,
+                .scan_type = {
+                        .sign           = 'u',
+                        .realbits       = 6,
+                        .storagebits    = 8,
+                },
+        },
+        IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static int as3935_read(struct as3935_state *st, unsigned int reg, int *val)
+{
+        u8 cmd;
+        int ret;
+
+        cmd = (AS3935_READ_DATA | AS3935_ADDRESS(reg)) >> 8;
+        ret = spi_w8r8(st->spi, cmd);
+        if (ret < 0)
+                return ret;
+        *val = ret;
+
+        return 0;
+};
+
+static int as3935_write(struct as3935_state *st,
+                                unsigned int reg,
+                                unsigned int val)
+{
+        u8 *buf = st->buf;
+
+        buf[0] = (AS3935_WRITE_DATA | AS3935_ADDRESS(reg)) >> 8;
+        buf[1] = val;
+
+        return spi_write(st->spi, buf, 2);
+};
+
+static ssize_t as3935_sensor_sensitivity_show(struct device *dev,
+                                        struct device_attribute *attr,
+                                        char *buf)
+{
+        struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
+        int val, ret;
+
+        ret = as3935_read(st, AS3935_AFE_GAIN, &val);
+        if (ret)
+                return ret;
+        val = (val & AS3935_AFE_MASK) >> 1;
+
+        return sprintf(buf, "%d\n", val);
+};
+
+static ssize_t as3935_sensor_sensitivity_store(struct device *dev,
+                                        struct device_attribute *attr,
+                                        const char *buf, size_t len)
+{
+        struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
+        unsigned long val;
+        int ret;
+
+        ret = kstrtoul((const char *) buf, 10, &val);
+        if (ret)
+                return -EINVAL;
+
+        if (val > AS3935_AFE_GAIN_MAX)
+                return -EINVAL;
+
+        as3935_write(st, AS3935_AFE_GAIN, val << 1);
+
+        return len;
+};
+
+static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR,
+        as3935_sensor_sensitivity_show, as3935_sensor_sensitivity_store, 0);
+
+
+static struct attribute *as3935_attributes[] = {
+        &iio_dev_attr_sensor_sensitivity.dev_attr.attr,
+        NULL,
+};
+
+static struct attribute_group as3935_attribute_group = {
+        .attrs = as3935_attributes,
+};
+
+static int as3935_read_raw(struct iio_dev *indio_dev,
+                           struct iio_chan_spec const *chan,
+                           int *val,
+                           int *val2,
+                           long m)
+{
+        struct as3935_state *st = iio_priv(indio_dev);
+        int ret;
+
+
+        switch (m) {
+        case IIO_CHAN_INFO_PROCESSED:
+        case IIO_CHAN_INFO_RAW:
+                *val2 = 0;
+                ret = as3935_read(st, AS3935_DATA, val);
+                if (ret)
+                        return ret;
+
+                if (m == IIO_CHAN_INFO_RAW)
+                        return IIO_VAL_INT;
+
+                /* storm out of range */
+                if (*val == AS3935_DATA_MASK)
+                        return -EINVAL;
+                *val *= 1000;
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        return IIO_VAL_INT;
+}
+
+static const struct iio_info as3935_info = {
+        .driver_module = THIS_MODULE,
+        .attrs = &as3935_attribute_group,
+        .read_raw = &as3935_read_raw,
+};
+
+static irqreturn_t as3935_trigger_handler(int irq, void *private)
+{
+        struct iio_poll_func *pf = private;
+        struct iio_dev *indio_dev = pf->indio_dev;
+        struct as3935_state *st = iio_priv(indio_dev);
+        int val, ret;
+
+        ret = as3935_read(st, AS3935_DATA, &val);
+        if (ret)
+                goto err_read;
+        val &= AS3935_DATA_MASK;
+        val *= 1000;
+
+        iio_push_to_buffers_with_timestamp(indio_dev, &val, pf->timestamp);
+err_read:
+        iio_trigger_notify_done(indio_dev->trig);
+
+        return IRQ_HANDLED;
+};
+
+static const struct iio_trigger_ops iio_interrupt_trigger_ops = {
+        .owner = THIS_MODULE,
+};
+
+static void as3935_event_work(struct work_struct *work)
+{
+        struct as3935_state *st;
+        int val;
+
+        st = container_of(work, struct as3935_state, work.work);
+
+        as3935_read(st, AS3935_INT, &val);
+        val &= AS3935_INT_MASK;
+
+        switch (val) {
+        case AS3935_EVENT_INT:
+                iio_trigger_poll(st->trig, iio_get_time_ns());
+                break;
+        case AS3935_NOISE_INT:
+                dev_warn(&st->spi->dev, "noise level is too high");
+                break;
+        }
+};
+
+static irqreturn_t as3935_interrupt_handler(int irq, void *private)
+{
+        struct iio_dev *indio_dev = private;
+        struct as3935_state *st = iio_priv(indio_dev);
+
+        /*
+         * Delay work for >2 milliseconds after an interrupt to allow
+         * estimated distance to recalculated.
+         */
+
+        schedule_delayed_work(&st->work, msecs_to_jiffies(3));
+
+        return IRQ_HANDLED;
+}
+
+static void calibrate_as3935(struct as3935_state *st)
+{
+        mutex_lock(&st->lock);
+
+        /* mask disturber interrupt bit */
+        as3935_write(st, AS3935_INT, BIT(5));
+
+        as3935_write(st, AS3935_CALIBRATE, 0x96);
+        as3935_write(st, AS3935_TUNE_CAP,
+                BIT(5) | (st->tune_cap / TUNE_CAP_DIV));
+
+        mdelay(2);
+        as3935_write(st, AS3935_TUNE_CAP, (st->tune_cap / TUNE_CAP_DIV));
+
+        mutex_unlock(&st->lock);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int as3935_suspend(struct spi_device *spi, pm_message_t msg)
+{
+        struct iio_dev *indio_dev = spi_get_drvdata(spi);
+        struct as3935_state *st = iio_priv(indio_dev);
+        int val, ret;
+
+        mutex_lock(&st->lock);
+        ret = as3935_read(st, AS3935_AFE_GAIN, &val);
+        if (ret)
+                goto err_suspend;
+        val |= AS3935_AFE_PWR_BIT;
+
+        ret = as3935_write(st, AS3935_AFE_GAIN, val);
+
+err_suspend:
+        mutex_unlock(&st->lock);
+
+        return ret;
+}
+
+static int as3935_resume(struct spi_device *spi)
+{
+        struct iio_dev *indio_dev = spi_get_drvdata(spi);
+        struct as3935_state *st = iio_priv(indio_dev);
+        int val, ret;
+
+        mutex_lock(&st->lock);
+        ret = as3935_read(st, AS3935_AFE_GAIN, &val);
+        if (ret)
+                goto err_resume;
+        val &= ~AS3935_AFE_PWR_BIT;
+        ret = as3935_write(st, AS3935_AFE_GAIN, val);
+
+err_resume:
+        mutex_unlock(&st->lock);
+
+        return ret;
+}
+#else
+#define as3935_suspend  NULL
+#define as3935_resume   NULL
+#endif
+
+static int as3935_probe(struct spi_device *spi)
+{
+        struct iio_dev *indio_dev;
+        struct iio_trigger *trig;
+        struct as3935_state *st;
+        struct device_node *np = spi->dev.of_node;
+        int ret;
+
+        /* Be sure lightning event interrupt is specified */
+        if (!spi->irq) {
+                dev_err(&spi->dev, "unable to get event interrupt\n");
+                return -EINVAL;
+        }
+
+        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(st));
+        if (!indio_dev)
+                return -ENOMEM;
+
+        st = iio_priv(indio_dev);
+        st->spi = spi;
+        st->tune_cap = 0;
+
+        spi_set_drvdata(spi, indio_dev);
+        mutex_init(&st->lock);
+        INIT_DELAYED_WORK(&st->work, as3935_event_work);
+
+        ret = of_property_read_u32(np,
+                        "ams,tuning-capacitor-pf", &st->tune_cap);
+        if (ret) {
+                st->tune_cap = 0;
+                dev_warn(&spi->dev,
+                        "no tuning-capacitor-pf set, defaulting to %d",
+                        st->tune_cap);
+        }
+
+        if (st->tune_cap > MAX_PF_CAP) {
+                dev_err(&spi->dev,
+                        "wrong tuning-capacitor-pf setting of %d\n",
+                        st->tune_cap);
+                return -EINVAL;
+        }
+
+        indio_dev->dev.parent = &spi->dev;
+        indio_dev->name = spi_get_device_id(spi)->name;
+        indio_dev->channels = as3935_channels;
+        indio_dev->num_channels = ARRAY_SIZE(as3935_channels);
+        indio_dev->modes = INDIO_DIRECT_MODE;
+        indio_dev->info = &as3935_info;
+
+        trig = devm_iio_trigger_alloc(&spi->dev, "%s-dev%d",
+                                      indio_dev->name, indio_dev->id);
+
+        if (!trig)
+                return -ENOMEM;
+
+        st->trig = trig;
+        trig->dev.parent = indio_dev->dev.parent;
+        iio_trigger_set_drvdata(trig, indio_dev);
+        trig->ops = &iio_interrupt_trigger_ops;
+
+        ret = iio_trigger_register(trig);
+        if (ret) {
+                dev_err(&spi->dev, "failed to register trigger\n");
+                return ret;
+        }
+
+        ret = iio_triggered_buffer_setup(indio_dev, NULL,
+                &as3935_trigger_handler, NULL);
+
+        if (ret) {
+                dev_err(&spi->dev, "cannot setup iio trigger\n");
+                goto unregister_trigger;
+        }
+
+        calibrate_as3935(st);
+
+        ret = devm_request_irq(&spi->dev, spi->irq,
+                                &as3935_interrupt_handler,
+                                IRQF_TRIGGER_RISING,
+                                dev_name(&spi->dev),
+                                indio_dev);
+
+        if (ret) {
+                dev_err(&spi->dev, "unable to request irq\n");
+                goto unregister_buffer;
+        }
+
+        ret = iio_device_register(indio_dev);
+        if (ret < 0) {
+                dev_err(&spi->dev, "unable to register device\n");
+                goto unregister_buffer;
+        }
+        return 0;
+
+unregister_buffer:
+        iio_triggered_buffer_cleanup(indio_dev);
+
+unregister_trigger:
+        iio_trigger_unregister(st->trig);
+
+        return ret;
+};
+
+static int as3935_remove(struct spi_device *spi)
+{
+        struct iio_dev *indio_dev = spi_get_drvdata(spi);
+        struct as3935_state *st = iio_priv(indio_dev);
+
+        iio_device_unregister(indio_dev);
+        iio_triggered_buffer_cleanup(indio_dev);
+        iio_trigger_unregister(st->trig);
+
+        return 0;
+};
+
+static const struct spi_device_id as3935_id[] = {
+        {"as3935", 0},
+        {},
+};
+MODULE_DEVICE_TABLE(spi, as3935_id);
+
+static struct spi_driver as3935_driver = {
+        .driver = {
+                .name   = "as3935",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = as3935_probe,
+        .remove         = as3935_remove,
+        .id_table       = as3935_id,
+        .suspend        = as3935_suspend,
+        .resume         = as3935_resume,
+};
+module_spi_driver(as3935_driver);
+
+MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
+MODULE_DESCRIPTION("AS3935 lightning sensor");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("spi:as3935");