platform: x86: dell-smo8800: Dell Latitude freefall driver (ACPI SMO8800/SMO8810)

This acpi driver provide supports for freefall sensors SMO8800/SMO8810 which
can be found on Dell Latitude laptops. Driver register /dev/freefall misc
device which has same interface as driver hp_accel freefall driver. So any
existing applications for HP freefall sensor /dev/freefall will work for with
this new driver for Dell Latitude laptops too.

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Cc: Sonal Santan <sonal.santan@gmail.com>
Tested-By: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Acked-By: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>

3 files changed, 244 insertions, 0 deletions

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 60d33834f28f..172f26ce59ac 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -127,6 +127,16 @@ config DELL_WMI_AIO
           To compile this driver as a module, choose M here: the module will
           be called dell-wmi-aio.
 
+config DELL_SMO8800
+        tristate "Dell Latitude freefall driver (ACPI SMO8800/SMO8810)"
+        depends on ACPI
+        ---help---
+          Say Y here if you want to support SMO8800/SMO8810 freefall device
+          on Dell Latitude laptops.
+
+          To compile this driver as a module, choose M here: the module will
+          be called dell-smo8800.
+
 
 config FUJITSU_LAPTOP
         tristate "Fujitsu Laptop Extras"
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 1a2eafc9d48e..c4ca428fd3db 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_COMPAL_LAPTOP)	+= compal-laptop.o
 obj-$(CONFIG_DELL_LAPTOP)       += dell-laptop.o
 obj-$(CONFIG_DELL_WMI)          += dell-wmi.o
 obj-$(CONFIG_DELL_WMI_AIO)      += dell-wmi-aio.o
+obj-$(CONFIG_DELL_SMO8800)      += dell-smo8800.o
 obj-$(CONFIG_ACER_WMI)          += acer-wmi.o
 obj-$(CONFIG_ACERHDF)           += acerhdf.o
 obj-$(CONFIG_HP_ACCEL)          += hp_accel.o
diff --git a/drivers/platform/x86/dell-smo8800.c b/drivers/platform/x86/dell-smo8800.c
new file mode 100644
index 000000000000..a653716055d1
--- /dev/null
+++ b/drivers/platform/x86/dell-smo8800.c
@@ -0,0 +1,233 @@
+/*
+ *  dell-smo8800.c - Dell Latitude ACPI SMO8800/SMO8810 freefall sensor driver
+ *
+ *  Copyright (C) 2012 Sonal Santan <sonal.santan@gmail.com>
+ *  Copyright (C) 2014 Pali Rohár <pali.rohar@gmail.com>
+ *
+ *  This is loosely based on lis3lv02d driver.
+ *
+ *  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.
+ */
+
+#define DRIVER_NAME "smo8800"
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/acpi.h>
+#include <linux/interrupt.h>
+#include <linux/miscdevice.h>
+
+struct smo8800_device {
+        u32 irq;                     /* acpi device irq */
+        atomic_t counter;            /* count after last read */
+        struct miscdevice miscdev;   /* for /dev/freefall */
+        unsigned long misc_opened;   /* whether the device is open */
+        wait_queue_head_t misc_wait; /* Wait queue for the misc dev */
+        struct device *dev;          /* acpi device */
+};
+
+static irqreturn_t smo8800_interrupt_quick(int irq, void *data)
+{
+        struct smo8800_device *smo8800 = data;
+
+        atomic_inc(&smo8800->counter);
+        wake_up_interruptible(&smo8800->misc_wait);
+        return IRQ_WAKE_THREAD;
+}
+
+static irqreturn_t smo8800_interrupt_thread(int irq, void *data)
+{
+        struct smo8800_device *smo8800 = data;
+
+        dev_info(smo8800->dev, "detected free fall\n");
+        return IRQ_HANDLED;
+}
+
+static acpi_status smo8800_get_resource(struct acpi_resource *resource,
+                                        void *context)
+{
+        struct acpi_resource_extended_irq *irq;
+
+        if (resource->type != ACPI_RESOURCE_TYPE_EXTENDED_IRQ)
+                return AE_OK;
+
+        irq = &resource->data.extended_irq;
+        if (!irq || !irq->interrupt_count)
+                return AE_OK;
+
+        *((u32 *)context) = irq->interrupts[0];
+        return AE_CTRL_TERMINATE;
+}
+
+static u32 smo8800_get_irq(struct acpi_device *device)
+{
+        u32 irq = 0;
+        acpi_status status;
+
+        status = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
+                                     smo8800_get_resource, &irq);
+        if (ACPI_FAILURE(status)) {
+                dev_err(&device->dev, "acpi_walk_resources failed\n");
+                return 0;
+        }
+
+        return irq;
+}
+
+static ssize_t smo8800_misc_read(struct file *file, char __user *buf,
+                                 size_t count, loff_t *pos)
+{
+        struct smo8800_device *smo8800 = container_of(file->private_data,
+                                         struct smo8800_device, miscdev);
+
+        u32 data = 0;
+        unsigned char byte_data = 0;
+        ssize_t retval = 1;
+
+        if (count < 1)
+                return -EINVAL;
+
+        atomic_set(&smo8800->counter, 0);
+        retval = wait_event_interruptible(smo8800->misc_wait,
+                                (data = atomic_xchg(&smo8800->counter, 0)));
+
+        if (retval)
+                return retval;
+
+        byte_data = 1;
+        retval = 1;
+
+        if (data < 255)
+                byte_data = data;
+        else
+                byte_data = 255;
+
+        if (put_user(byte_data, buf))
+                retval = -EFAULT;
+
+        return retval;
+}
+
+static int smo8800_misc_open(struct inode *inode, struct file *file)
+{
+        struct smo8800_device *smo8800 = container_of(file->private_data,
+                                         struct smo8800_device, miscdev);
+
+        if (test_and_set_bit(0, &smo8800->misc_opened))
+                return -EBUSY; /* already open */
+
+        atomic_set(&smo8800->counter, 0);
+        return 0;
+}
+
+static int smo8800_misc_release(struct inode *inode, struct file *file)
+{
+        struct smo8800_device *smo8800 = container_of(file->private_data,
+                                         struct smo8800_device, miscdev);
+
+        clear_bit(0, &smo8800->misc_opened); /* release the device */
+        return 0;
+}
+
+static const struct file_operations smo8800_misc_fops = {
+        .owner = THIS_MODULE,
+        .read = smo8800_misc_read,
+        .open = smo8800_misc_open,
+        .release = smo8800_misc_release,
+};
+
+static int smo8800_add(struct acpi_device *device)
+{
+        int err;
+        struct smo8800_device *smo8800;
+
+        smo8800 = devm_kzalloc(&device->dev, sizeof(*smo8800), GFP_KERNEL);
+        if (!smo8800) {
+                dev_err(&device->dev, "failed to allocate device data\n");
+                return -ENOMEM;
+        }
+
+        smo8800->dev = &device->dev;
+        smo8800->miscdev.minor = MISC_DYNAMIC_MINOR;
+        smo8800->miscdev.name = "freefall";
+        smo8800->miscdev.fops = &smo8800_misc_fops;
+
+        init_waitqueue_head(&smo8800->misc_wait);
+
+        err = misc_register(&smo8800->miscdev);
+        if (err) {
+                dev_err(&device->dev, "failed to register misc dev: %d\n", err);
+                return err;
+        }
+
+        device->driver_data = smo8800;
+
+        smo8800->irq = smo8800_get_irq(device);
+        if (!smo8800->irq) {
+                dev_err(&device->dev, "failed to obtain IRQ\n");
+                err = -EINVAL;
+                goto error;
+        }
+
+        err = request_threaded_irq(smo8800->irq, smo8800_interrupt_quick,
+                                   smo8800_interrupt_thread,
+                                   IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+                                   DRIVER_NAME, smo8800);
+        if (err) {
+                dev_err(&device->dev,
+                        "failed to request thread for IRQ %d: %d\n",
+                        smo8800->irq, err);
+                goto error;
+        }
+
+        dev_dbg(&device->dev, "device /dev/freefall registered with IRQ %d\n",
+                 smo8800->irq);
+        return 0;
+
+error:
+        misc_deregister(&smo8800->miscdev);
+        return err;
+}
+
+static int smo8800_remove(struct acpi_device *device)
+{
+        struct smo8800_device *smo8800 = device->driver_data;
+
+        free_irq(smo8800->irq, smo8800);
+        misc_deregister(&smo8800->miscdev);
+        dev_dbg(&device->dev, "device /dev/freefall unregistered\n");
+        return 0;
+}
+
+static const struct acpi_device_id smo8800_ids[] = {
+        { "SMO8800", 0 },
+        { "SMO8810", 0 },
+        { "", 0 },
+};
+
+MODULE_DEVICE_TABLE(acpi, smo8800_ids);
+
+static struct acpi_driver smo8800_driver = {
+        .name = DRIVER_NAME,
+        .class = "Latitude",
+        .ids = smo8800_ids,
+        .ops = {
+                .add = smo8800_add,
+                .remove = smo8800_remove,
+        },
+        .owner = THIS_MODULE,
+};
+
+module_acpi_driver(smo8800_driver);
+
+MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO8800/SMO8810)");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sonal Santan, Pali Rohár");