Introduce a dev_attr which can be used to combine the accelerator
and brake pedals into a single axis. This is useful for older games
which can not handle seperate accelerator and brake.

Signed-off-by: Simon Wood <si...@mungewell.org>
---
 .../ABI/testing/sysfs-driver-hid-logitech-lg4ff    |  9 ++++
 drivers/hid/hid-lg4ff.c                            | 58 ++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-driver-hid-logitech-lg4ff 
b/Documentation/ABI/testing/sysfs-driver-hid-logitech-lg4ff
index db197a8..9cd7c5a 100644
--- a/Documentation/ABI/testing/sysfs-driver-hid-logitech-lg4ff
+++ b/Documentation/ABI/testing/sysfs-driver-hid-logitech-lg4ff
@@ -50,3 +50,12 @@ Description: Displays the real model of the wheel regardless 
of any
                alternate mode the wheel might be switched to.
                It is a read-only value.
                This entry is not created for devices that have only one mode.
+
+What:          /sys/bus/hid/drivers/logitech/<dev>/combine_pedals
+Date:          Sep 2016
+KernelVersion: 4.9
+Contact:       Simon Wood <si...@mungewell.org>
+Description:   Controls whether a combined value of accelerator and brake is
+               reported on the Y axis of the controller. Useful for older games
+               which can do not work with separate accelerator/brake axis.
+               Off ('0') by default, enabled by setting '1'.
diff --git a/drivers/hid/hid-lg4ff.c b/drivers/hid/hid-lg4ff.c
index af3a8ec..ca31ce4 100644
--- a/drivers/hid/hid-lg4ff.c
+++ b/drivers/hid/hid-lg4ff.c
@@ -75,6 +75,7 @@ static void lg4ff_set_range_g25(struct hid_device *hid, u16 
range);
 
 struct lg4ff_wheel_data {
        const u32 product_id;
+       u16 combine;
        u16 range;
        const u16 min_range;
        const u16 max_range;
@@ -345,6 +346,7 @@ static void lg4ff_init_wheel_data(struct lg4ff_wheel_data * 
const wdata, const s
        {
                struct lg4ff_wheel_data t_wdata =  { .product_id = 
wheel->product_id,
                                                     .real_product_id = 
real_product_id,
+                                                    .combine = 0,
                                                     .min_range = 
wheel->min_range,
                                                     .max_range = 
wheel->max_range,
                                                     .set_range = 
wheel->set_range,
@@ -885,6 +887,58 @@ static ssize_t lg4ff_alternate_modes_store(struct device 
*dev, struct device_att
 }
 static DEVICE_ATTR(alternate_modes, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | 
S_IROTH, lg4ff_alternate_modes_show, lg4ff_alternate_modes_store);
 
+static ssize_t lg4ff_combine_show(struct device *dev, struct device_attribute 
*attr,
+                               char *buf)
+{
+       struct hid_device *hid = to_hid_device(dev);
+       struct lg4ff_device_entry *entry;
+       struct lg_drv_data *drv_data;
+       size_t count;
+
+       drv_data = hid_get_drvdata(hid);
+       if (!drv_data) {
+               hid_err(hid, "Private driver data not found!\n");
+               return 0;
+       }
+
+       entry = drv_data->device_props;
+       if (!entry) {
+               hid_err(hid, "Device properties not found!\n");
+               return 0;
+       }
+
+       count = scnprintf(buf, PAGE_SIZE, "%u\n", entry->wdata.combine);
+       return count;
+}
+
+static ssize_t lg4ff_combine_store(struct device *dev, struct device_attribute 
*attr,
+                                const char *buf, size_t count)
+{
+       struct hid_device *hid = to_hid_device(dev);
+       struct lg4ff_device_entry *entry;
+       struct lg_drv_data *drv_data;
+       u16 combine = simple_strtoul(buf, NULL, 10);
+
+       drv_data = hid_get_drvdata(hid);
+       if (!drv_data) {
+               hid_err(hid, "Private driver data not found!\n");
+               return -EINVAL;
+       }
+
+       entry = drv_data->device_props;
+       if (!entry) {
+               hid_err(hid, "Device properties not found!\n");
+               return -EINVAL;
+       }
+
+       if (combine > 1)
+               combine = 1;
+
+       entry->wdata.combine = combine;
+       return count;
+}
+static DEVICE_ATTR(combine_pedals, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | 
S_IROTH, lg4ff_combine_show, lg4ff_combine_store);
+
 /* Export the currently set range of the wheel */
 static ssize_t lg4ff_range_show(struct device *dev, struct device_attribute 
*attr,
                                char *buf)
@@ -1259,6 +1313,9 @@ int lg4ff_init(struct hid_device *hid)
        }
 
        /* Create sysfs interface */
+       error = device_create_file(&hid->dev, &dev_attr_combine_pedals);
+       if (error)
+               hid_warn(hid, "Unable to create sysfs interface for 
\"combine\", errno %d\n", error);
        error = device_create_file(&hid->dev, &dev_attr_range);
        if (error)
                hid_warn(hid, "Unable to create sysfs interface for \"range\", 
errno %d\n", error);
@@ -1358,6 +1415,7 @@ int lg4ff_deinit(struct hid_device *hid)
                device_remove_file(&hid->dev, &dev_attr_alternate_modes);
        }
 
+       device_remove_file(&hid->dev, &dev_attr_combine_pedals);
        device_remove_file(&hid->dev, &dev_attr_range);
 #ifdef CONFIG_LEDS_CLASS
        {
-- 
2.7.4

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