Input: add generic GPIO-tilt driver

There exist tilt switches that simply report their tilt-state via
some gpios. The number and orientation of their axes can vary
depending on the switch used and the build of the device. Also two
or more one-axis switches could be combined to provide multi-dimensional
orientation.

One example of a device using such a switch is the family of Qisda
ebook readers, where the switch provides information about the
landscape / portrait orientation of the device. The example in
Documentation/input/gpio-tilt.txt documents exactly this one-axis
device.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

5 files changed, 404 insertions, 0 deletions

diff --git a/Documentation/input/gpio-tilt.txt b/Documentation/input/gpio-tilt.txt
new file mode 100644
index 000000000000..06d60c3ff5e7
--- /dev/null
+++ b/Documentation/input/gpio-tilt.txt
@@ -0,0 +1,103 @@
+Driver for tilt-switches connected via GPIOs
+============================================
+
+Generic driver to read data from tilt switches connected via gpios.
+Orientation can be provided by one or more than one tilt switches,
+i.e. each tilt switch providing one axis, and the number of axes
+is also not limited.
+
+
+Data structures:
+----------------
+
+The array of struct gpio in the gpios field is used to list the gpios
+that represent the current tilt state.
+
+The array of struct gpio_tilt_axis describes the axes that are reported
+to the input system. The values set therein are used for the
+input_set_abs_params calls needed to init the axes.
+
+The array of struct gpio_tilt_state maps gpio states to the corresponding
+values to report. The gpio state is represented as a bitfield where the
+bit-index corresponds to the index of the gpio in the struct gpio array.
+In the same manner the values stored in the axes array correspond to
+the elements of the gpio_tilt_axis-array.
+
+
+Example:
+--------
+
+Example configuration for a single TS1003 tilt switch that rotates around
+one axis in 4 steps and emitts the current tilt via two GPIOs.
+
+static int sg060_tilt_enable(struct device *dev) {
+        /* code to enable the sensors */
+};
+
+static void sg060_tilt_disable(struct device *dev) {
+        /* code to disable the sensors */
+};
+
+static struct gpio sg060_tilt_gpios[] = {
+        { SG060_TILT_GPIO_SENSOR1, GPIOF_IN, "tilt_sensor1" },
+        { SG060_TILT_GPIO_SENSOR2, GPIOF_IN, "tilt_sensor2" },
+};
+
+static struct gpio_tilt_state sg060_tilt_states[] = {
+        {
+                .gpios = (0 << 1) | (0 << 0),
+                .axes = (int[]) {
+                        0,
+                },
+        }, {
+                .gpios = (0 << 1) | (1 << 0),
+                .axes = (int[]) {
+                        1, /* 90 degrees */
+                },
+        }, {
+                .gpios = (1 << 1) | (1 << 0),
+                .axes = (int[]) {
+                        2, /* 180 degrees */
+                },
+        }, {
+                .gpios = (1 << 1) | (0 << 0),
+                .axes = (int[]) {
+                        3, /* 270 degrees */
+                },
+        },
+};
+
+static struct gpio_tilt_axis sg060_tilt_axes[] = {
+        {
+                .axis = ABS_RY,
+                .min = 0,
+                .max = 3,
+                .fuzz = 0,
+                .flat = 0,
+        },
+};
+
+static struct gpio_tilt_platform_data sg060_tilt_pdata= {
+        .gpios = sg060_tilt_gpios,
+        .nr_gpios = ARRAY_SIZE(sg060_tilt_gpios),
+
+        .axes = sg060_tilt_axes,
+        .nr_axes = ARRAY_SIZE(sg060_tilt_axes),
+
+        .states = sg060_tilt_states,
+        .nr_states = ARRAY_SIZE(sg060_tilt_states),
+
+        .debounce_interval = 100,
+
+        .poll_interval = 1000,
+        .enable = sg060_tilt_enable,
+        .disable = sg060_tilt_disable,
+};
+
+static struct platform_device sg060_device_tilt = {
+        .name = "gpio-tilt-polled",
+        .id = -1,
+        .dev = {
+                .platform_data = &sg060_tilt_pdata,
+        },
+};
diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 22d875fde53a..e53b443d1e33 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -179,6 +179,20 @@ config INPUT_APANEL
          To compile this driver as a module, choose M here: the module will
          be called apanel.
 
+config INPUT_GPIO_TILT_POLLED
+        tristate "Polled GPIO tilt switch"
+        depends on GENERIC_GPIO
+        select INPUT_POLLDEV
+        help
+          This driver implements support for tilt switches connected
+          to GPIO pins that are not capable of generating interrupts.
+
+          The list of gpios to use and the mapping of their states
+          to specific angles is done via platform data.
+
+          To compile this driver as a module, choose M here: the
+          module will be called gpio_tilt_polled.
+
 config INPUT_IXP4XX_BEEPER
         tristate "IXP4XX Beeper support"
         depends on ARCH_IXP4XX
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index a244fc6a781c..90070c1a4ad3 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_INPUT_CMA3000_I2C)		+= cma3000_d0x_i2c.o
 obj-$(CONFIG_INPUT_COBALT_BTNS)         += cobalt_btns.o
 obj-$(CONFIG_INPUT_DM355EVM)            += dm355evm_keys.o
 obj-$(CONFIG_HP_SDC_RTC)                += hp_sdc_rtc.o
+obj-$(CONFIG_INPUT_GPIO_TILT_POLLED)    += gpio_tilt_polled.o
 obj-$(CONFIG_INPUT_IXP4XX_BEEPER)       += ixp4xx-beeper.o
 obj-$(CONFIG_INPUT_KEYSPAN_REMOTE)      += keyspan_remote.o
 obj-$(CONFIG_INPUT_KXTJ9)               += kxtj9.o
diff --git a/drivers/input/misc/gpio_tilt_polled.c b/drivers/input/misc/gpio_tilt_polled.c
new file mode 100644
index 000000000000..277a0574c199
--- /dev/null
+++ b/drivers/input/misc/gpio_tilt_polled.c
@@ -0,0 +1,213 @@
+/*
+ *  Driver for tilt switches connected via GPIO lines
+ *  not capable of generating interrupts
+ *
+ *  Copyright (C) 2011 Heiko Stuebner <heiko@sntech.de>
+ *
+ *  based on: drivers/input/keyboard/gpio_keys_polled.c
+ *
+ *  Copyright (C) 2007-2010 Gabor Juhos <juhosg@openwrt.org>
+ *  Copyright (C) 2010 Nuno Goncalves <nunojpg@gmail.com>
+ *
+ *  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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/input-polldev.h>
+#include <linux/ioport.h>
+#include <linux/platform_device.h>
+#include <linux/gpio.h>
+#include <linux/input/gpio_tilt.h>
+
+#define DRV_NAME        "gpio-tilt-polled"
+
+struct gpio_tilt_polled_dev {
+        struct input_polled_dev *poll_dev;
+        struct device *dev;
+        const struct gpio_tilt_platform_data *pdata;
+
+        int last_state;
+
+        int threshold;
+        int count;
+};
+
+static void gpio_tilt_polled_poll(struct input_polled_dev *dev)
+{
+        struct gpio_tilt_polled_dev *tdev = dev->private;
+        const struct gpio_tilt_platform_data *pdata = tdev->pdata;
+        struct input_dev *input = dev->input;
+        struct gpio_tilt_state *tilt_state = NULL;
+        int state, i;
+
+        if (tdev->count < tdev->threshold) {
+                tdev->count++;
+        } else {
+                state = 0;
+                for (i = 0; i < pdata->nr_gpios; i++)
+                        state |= (!!gpio_get_value(pdata->gpios[i].gpio) << i);
+
+                if (state != tdev->last_state) {
+                        for (i = 0; i < pdata->nr_states; i++)
+                                if (pdata->states[i].gpios == state)
+                                        tilt_state = &pdata->states[i];
+
+                        if (tilt_state) {
+                                for (i = 0; i < pdata->nr_axes; i++)
+                                        input_report_abs(input,
+                                                         pdata->axes[i].axis,
+                                                         tilt_state->axes[i]);
+
+                                input_sync(input);
+                        }
+
+                        tdev->count = 0;
+                        tdev->last_state = state;
+                }
+        }
+}
+
+static void gpio_tilt_polled_open(struct input_polled_dev *dev)
+{
+        struct gpio_tilt_polled_dev *tdev = dev->private;
+        const struct gpio_tilt_platform_data *pdata = tdev->pdata;
+
+        if (pdata->enable)
+                pdata->enable(tdev->dev);
+
+        /* report initial state of the axes */
+        tdev->last_state = -1;
+        tdev->count = tdev->threshold;
+        gpio_tilt_polled_poll(tdev->poll_dev);
+}
+
+static void gpio_tilt_polled_close(struct input_polled_dev *dev)
+{
+        struct gpio_tilt_polled_dev *tdev = dev->private;
+        const struct gpio_tilt_platform_data *pdata = tdev->pdata;
+
+        if (pdata->disable)
+                pdata->disable(tdev->dev);
+}
+
+static int __devinit gpio_tilt_polled_probe(struct platform_device *pdev)
+{
+        const struct gpio_tilt_platform_data *pdata = pdev->dev.platform_data;
+        struct device *dev = &pdev->dev;
+        struct gpio_tilt_polled_dev *tdev;
+        struct input_polled_dev *poll_dev;
+        struct input_dev *input;
+        int error, i;
+
+        if (!pdata || !pdata->poll_interval)
+                return -EINVAL;
+
+        tdev = kzalloc(sizeof(struct gpio_tilt_polled_dev), GFP_KERNEL);
+        if (!tdev) {
+                dev_err(dev, "no memory for private data\n");
+                return -ENOMEM;
+        }
+
+        error = gpio_request_array(pdata->gpios, pdata->nr_gpios);
+        if (error) {
+                dev_err(dev,
+                        "Could not request tilt GPIOs: %d\n", error);
+                goto err_free_tdev;
+        }
+
+        poll_dev = input_allocate_polled_device();
+        if (!poll_dev) {
+                dev_err(dev, "no memory for polled device\n");
+                error = -ENOMEM;
+                goto err_free_gpios;
+        }
+
+        poll_dev->private = tdev;
+        poll_dev->poll = gpio_tilt_polled_poll;
+        poll_dev->poll_interval = pdata->poll_interval;
+        poll_dev->open = gpio_tilt_polled_open;
+        poll_dev->close = gpio_tilt_polled_close;
+
+        input = poll_dev->input;
+
+        input->name = pdev->name;
+        input->phys = DRV_NAME"/input0";
+        input->dev.parent = &pdev->dev;
+
+        input->id.bustype = BUS_HOST;
+        input->id.vendor = 0x0001;
+        input->id.product = 0x0001;
+        input->id.version = 0x0100;
+
+        __set_bit(EV_ABS, input->evbit);
+        for (i = 0; i < pdata->nr_axes; i++)
+                input_set_abs_params(input, pdata->axes[i].axis,
+                                     pdata->axes[i].min, pdata->axes[i].max,
+                                     pdata->axes[i].fuzz, pdata->axes[i].flat);
+
+        tdev->threshold = DIV_ROUND_UP(pdata->debounce_interval,
+                                       pdata->poll_interval);
+
+        tdev->poll_dev = poll_dev;
+        tdev->dev = dev;
+        tdev->pdata = pdata;
+
+        error = input_register_polled_device(poll_dev);
+        if (error) {
+                dev_err(dev, "unable to register polled device, err=%d\n",
+                        error);
+                goto err_free_polldev;
+        }
+
+        platform_set_drvdata(pdev, tdev);
+
+        return 0;
+
+err_free_polldev:
+        input_free_polled_device(poll_dev);
+err_free_gpios:
+        gpio_free_array(pdata->gpios, pdata->nr_gpios);
+err_free_tdev:
+        kfree(tdev);
+
+        return error;
+}
+
+static int __devexit gpio_tilt_polled_remove(struct platform_device *pdev)
+{
+        struct gpio_tilt_polled_dev *tdev = platform_get_drvdata(pdev);
+        const struct gpio_tilt_platform_data *pdata = tdev->pdata;
+
+        platform_set_drvdata(pdev, NULL);
+
+        input_unregister_polled_device(tdev->poll_dev);
+        input_free_polled_device(tdev->poll_dev);
+
+        gpio_free_array(pdata->gpios, pdata->nr_gpios);
+
+        kfree(tdev);
+
+        return 0;
+}
+
+static struct platform_driver gpio_tilt_polled_driver = {
+        .probe  = gpio_tilt_polled_probe,
+        .remove = __devexit_p(gpio_tilt_polled_remove),
+        .driver = {
+                .name   = DRV_NAME,
+                .owner  = THIS_MODULE,
+        },
+};
+
+module_platform_driver(gpio_tilt_polled_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Heiko Stuebner <heiko@sntech.de>");
+MODULE_DESCRIPTION("Polled GPIO tilt driver");
+MODULE_ALIAS("platform:" DRV_NAME);
diff --git a/include/linux/input/gpio_tilt.h b/include/linux/input/gpio_tilt.h
new file mode 100644
index 000000000000..c1cc52d380e0
--- /dev/null
+++ b/include/linux/input/gpio_tilt.h
@@ -0,0 +1,73 @@
+#ifndef _INPUT_GPIO_TILT_H
+#define _INPUT_GPIO_TILT_H
+
+/**
+ * struct gpio_tilt_axis - Axis used by the tilt switch
+ * @axis:               Constant describing the axis, e.g. ABS_X
+ * @min:                minimum value for abs_param
+ * @max:                maximum value for abs_param
+ * @fuzz:               fuzz value for abs_param
+ * @flat:               flat value for abs_param
+ */
+struct gpio_tilt_axis {
+        int axis;
+        int min;
+        int max;
+        int fuzz;
+        int flat;
+};
+
+/**
+ * struct gpio_tilt_state - state description
+ * @gpios:              bitfield of gpio target-states for the value
+ * @axes:               array containing the axes settings for the gpio state
+ *                      The array indizes must correspond to the axes defined
+ *                      in platform_data
+ *
+ * This structure describes a supported axis settings
+ * and the necessary gpio-state which represent it.
+ *
+ * The n-th bit in the bitfield describes the state of the n-th GPIO
+ * from the gpios-array defined in gpio_regulator_config below.
+ */
+struct gpio_tilt_state {
+        int gpios;
+        int *axes;
+};
+
+/**
+ * struct gpio_tilt_platform_data
+ * @gpios:              Array containing the gpios determining the tilt state
+ * @nr_gpios:           Number of gpios
+ * @axes:               Array of gpio_tilt_axis descriptions
+ * @nr_axes:            Number of axes
+ * @states:             Array of gpio_tilt_state entries describing
+ *                      the gpio state for specific tilts
+ * @nr_states:          Number of states available
+ * @debounce_interval:  debounce ticks interval in msecs
+ * @poll_interval:      polling interval in msecs - for polling driver only
+ * @enable:             callback to enable the tilt switch
+ * @disable:            callback to disable the tilt switch
+ *
+ * This structure contains gpio-tilt-switch configuration
+ * information that must be passed by platform code to the
+ * gpio-tilt input driver.
+ */
+struct gpio_tilt_platform_data {
+        struct gpio *gpios;
+        int nr_gpios;
+
+        struct gpio_tilt_axis *axes;
+        int nr_axes;
+
+        struct gpio_tilt_state *states;
+        int nr_states;
+
+        int debounce_interval;
+
+        unsigned int poll_interval;
+        int (*enable)(struct device *dev);
+        void (*disable)(struct device *dev);
+};
+
+#endif