HID: wacom: Add support for Express Key Remote.

This device is pad (buttons) only, there is no stylus or touch. Up to
five remotes can pair with the device's associated USB dongle.

Signed-off-by: Aaron Skomra <[email protected]>
Reviewed-by: Jason Gerecke <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>

Author: skomra

Documentation/ABI/testing/sysfs-driver-wacom

@@ -77,3 +77,22 @@ Description:
 		The format is also scrambled, like in the USB mode, and it can
 		be summarized by converting 76543210 into GECA6420.
 					    HGFEDCBA      HFDB7531
+
+What:		/sys/bus/hid/devices/<bus>:<vid>:<pid>.<n>/wacom_remote/unpair_remote
+Date:		July 2015
+Contact:	[email protected]
+Description:
+		Writing the character sequence '*' followed by a newline to
+		this file will delete all of the current pairings on the
+		device. Other character sequences are reserved. This file is
+		write only.
+
+What:		/sys/bus/hid/devices/<bus>:<vid>:<pid>.<n>/wacom_remote/<serial_number>/remote_mode
+Date:		July 2015
+Contact:	[email protected]
+Description:
+		Reading from this file reports the mode status of the
+		remote as indicated by the LED lights on the device. If no
+		reports have been received from the paired device, reading
+		from this file will report '-1'. The mode is read-only
+		and cannot be set through the driver.

drivers/hid/wacom.h

@@ -113,7 +113,7 @@ struct wacom {
 	struct mutex lock;
 	struct work_struct work;
 	struct wacom_led {
-		u8 select[2]; /* status led selector (0..3) */
+		u8 select[5]; /* status led selector (0..3) */
 		u8 llv;       /* status led brightness no button (1..127) */
 		u8 hlv;       /* status led brightness button pressed (1..127) */
 		u8 img_lum;   /* OLED matrix display brightness */
@@ -123,6 +123,8 @@ struct wacom {
 	struct power_supply *ac;
 	struct power_supply_desc battery_desc;
 	struct power_supply_desc ac_desc;
+	struct kobject *remote_dir;
+	struct attribute_group remote_group[5];
 };
 
 static inline void wacom_schedule_work(struct wacom_wac *wacom_wac)
@@ -147,4 +149,7 @@ int wacom_wac_event(struct hid_device *hdev, struct hid_field *field,
 		struct hid_usage *usage, __s32 value);
 void wacom_wac_report(struct hid_device *hdev, struct hid_report *report);
 void wacom_battery_work(struct work_struct *work);
+int wacom_remote_create_attr_group(struct wacom *wacom, __u32 serial,
+				   int index);
+void wacom_remote_destroy_attr_group(struct wacom *wacom, __u32 serial);
 #endif

drivers/hid/wacom_sys.c

@@ -23,9 +23,13 @@
 #define WAC_CMD_ICON_XFER	0x23
 #define WAC_CMD_ICON_BT_XFER	0x26
 #define WAC_CMD_RETRIES		10
+#define WAC_CMD_DELETE_PAIRING	0x20
+#define WAC_CMD_UNPAIR_ALL	0xFF
+#define WAC_REMOTE_SERIAL_MAX_STRLEN	9
 
 #define DEV_ATTR_RW_PERM (S_IRUGO | S_IWUSR | S_IWGRP)
 #define DEV_ATTR_WO_PERM (S_IWUSR | S_IWGRP)
+#define DEV_ATTR_RO_PERM (S_IRUSR | S_IRGRP)
 
 static int wacom_get_report(struct hid_device *hdev, u8 type, u8 *buf,
 			    size_t size, unsigned int retries)
@@ -1119,6 +1123,189 @@ static ssize_t wacom_store_speed(struct device *dev,
 static DEVICE_ATTR(speed, DEV_ATTR_RW_PERM,
 		wacom_show_speed, wacom_store_speed);
 
+
+static ssize_t wacom_show_remote_mode(struct kobject *kobj,
+				      struct kobj_attribute *kattr,
+				      char *buf, int index)
+{
+	struct device *dev = container_of(kobj->parent, struct device, kobj);
+	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
+	struct wacom *wacom = hid_get_drvdata(hdev);
+	u8 mode;
+
+	mode = wacom->led.select[index];
+	if (mode >= 0 && mode < 3)
+		return snprintf(buf, PAGE_SIZE, "%d\n", mode);
+	else
+		return snprintf(buf, PAGE_SIZE, "%d\n", -1);
+}
+
+#define DEVICE_EKR_ATTR_GROUP(SET_ID)					\
+static ssize_t wacom_show_remote##SET_ID##_mode(struct kobject *kobj,	\
+			       struct kobj_attribute *kattr, char *buf)	\
+{									\
+	return wacom_show_remote_mode(kobj, kattr, buf, SET_ID);	\
+}									\
+static struct kobj_attribute remote##SET_ID##_mode_attr = {		\
+	.attr = {.name = "remote_mode",					\
+		.mode = DEV_ATTR_RO_PERM},				\
+	.show = wacom_show_remote##SET_ID##_mode,			\
+};									\
+static struct attribute *remote##SET_ID##_serial_attrs[] = {		\
+	&remote##SET_ID##_mode_attr.attr,				\
+	NULL								\
+};									\
+static struct attribute_group remote##SET_ID##_serial_group = {		\
+	.name = NULL,							\
+	.attrs = remote##SET_ID##_serial_attrs,				\
+}
+
+DEVICE_EKR_ATTR_GROUP(0);
+DEVICE_EKR_ATTR_GROUP(1);
+DEVICE_EKR_ATTR_GROUP(2);
+DEVICE_EKR_ATTR_GROUP(3);
+DEVICE_EKR_ATTR_GROUP(4);
+
+int wacom_remote_create_attr_group(struct wacom *wacom, __u32 serial, int index)
+{
+	int error = 0;
+	char *buf;
+	struct wacom_wac *wacom_wac = &wacom->wacom_wac;
+
+	wacom_wac->serial[index] = serial;
+
+	buf = kzalloc(WAC_REMOTE_SERIAL_MAX_STRLEN, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+	snprintf(buf, WAC_REMOTE_SERIAL_MAX_STRLEN, "%d", serial);
+	wacom->remote_group[index].name = buf;
+
+	error = sysfs_create_group(wacom->remote_dir,
+				   &wacom->remote_group[index]);
+	if (error) {
+		hid_err(wacom->hdev,
+			"cannot create sysfs group err: %d\n", error);
+		kobject_put(wacom->remote_dir);
+		return error;
+	}
+
+	return 0;
+}
+
+void wacom_remote_destroy_attr_group(struct wacom *wacom, __u32 serial)
+{
+	struct wacom_wac *wacom_wac = &wacom->wacom_wac;
+	int i;
+
+	if (!serial)
+		return;
+
+	for (i = 0; i < WACOM_MAX_REMOTES; i++) {
+		if (wacom_wac->serial[i] == serial) {
+			wacom_wac->serial[i] = 0;
+			wacom->led.select[i] = WACOM_STATUS_UNKNOWN;
+			if (wacom->remote_group[i].name) {
+				sysfs_remove_group(wacom->remote_dir,
+						   &wacom->remote_group[i]);
+				kfree(wacom->remote_group[i].name);
+				wacom->remote_group[i].name = NULL;
+			}
+		}
+	}
+}
+
+static int wacom_cmd_unpair_remote(struct wacom *wacom, unsigned char selector)
+{
+	const size_t buf_size = 2;
+	unsigned char *buf;
+	int retval;
+
+	buf = kzalloc(buf_size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	buf[0] = WAC_CMD_DELETE_PAIRING;
+	buf[1] = selector;
+
+	retval = wacom_set_report(wacom->hdev, HID_OUTPUT_REPORT, buf,
+				  buf_size, WAC_CMD_RETRIES);
+	kfree(buf);
+
+	return retval;
+}
+
+static ssize_t wacom_store_unpair_remote(struct kobject *kobj,
+					 struct kobj_attribute *attr,
+					 const char *buf, size_t count)
+{
+	unsigned char selector = 0;
+	struct device *dev = container_of(kobj->parent, struct device, kobj);
+	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
+	struct wacom *wacom = hid_get_drvdata(hdev);
+	int err;
+
+	if (!strncmp(buf, "*\n", 2)) {
+		selector = WAC_CMD_UNPAIR_ALL;
+	} else {
+		hid_info(wacom->hdev, "remote: unrecognized unpair code: %s\n",
+			 buf);
+		return -1;
+	}
+
+	mutex_lock(&wacom->lock);
+
+	err = wacom_cmd_unpair_remote(wacom, selector);
+	mutex_unlock(&wacom->lock);
+
+	return err < 0 ? err : count;
+}
+
+static struct kobj_attribute unpair_remote_attr = {
+	.attr = {.name = "unpair_remote", .mode = 0200},
+	.store = wacom_store_unpair_remote,
+};
+
+static const struct attribute *remote_unpair_attrs[] = {
+	&unpair_remote_attr.attr,
+	NULL
+};
+
+static int wacom_initialize_remote(struct wacom *wacom)
+{
+	int error = 0;
+	struct wacom_wac *wacom_wac = &(wacom->wacom_wac);
+	int i;
+
+	if (wacom->wacom_wac.features.type != REMOTE)
+		return 0;
+
+	wacom->remote_group[0] = remote0_serial_group;
+	wacom->remote_group[1] = remote1_serial_group;
+	wacom->remote_group[2] = remote2_serial_group;
+	wacom->remote_group[3] = remote3_serial_group;
+	wacom->remote_group[4] = remote4_serial_group;
+
+	wacom->remote_dir = kobject_create_and_add("wacom_remote",
+						   &wacom->hdev->dev.kobj);
+	if (!wacom->remote_dir)
+		return -ENOMEM;
+
+	error = sysfs_create_files(wacom->remote_dir, remote_unpair_attrs);
+
+	if (error) {
+		hid_err(wacom->hdev,
+			"cannot create sysfs group err: %d\n", error);
+		return error;
+	}
+
+	for (i = 0; i < WACOM_MAX_REMOTES; i++) {
+		wacom->led.select[i] = WACOM_STATUS_UNKNOWN;
+		wacom_wac->serial[i] = 0;
+	}
+
+	return 0;
+}
+
 static struct input_dev *wacom_allocate_input(struct wacom *wacom)
 {
 	struct input_dev *input_dev;
@@ -1164,6 +1351,8 @@ static void wacom_clean_inputs(struct wacom *wacom)
 		else
 			input_free_device(wacom->wacom_wac.pad_input);
 	}
+	if (wacom->remote_dir)
+		kobject_put(wacom->remote_dir);
 	wacom->wacom_wac.pen_input = NULL;
 	wacom->wacom_wac.touch_input = NULL;
 	wacom->wacom_wac.pad_input = NULL;
@@ -1243,10 +1432,16 @@ static int wacom_register_inputs(struct wacom *wacom)
 		error = wacom_initialize_leds(wacom);
 		if (error)
 			goto fail_leds;
+
+		error = wacom_initialize_remote(wacom);
+		if (error)
+			goto fail_remote;
 	}
 
 	return 0;
 
+fail_remote:
+	wacom_destroy_leds(wacom);
 fail_leds:
 	input_unregister_device(pad_input_dev);
 	pad_input_dev = NULL;