drivers/gpu/drm/bridge/nxp-ptn3460.c - linux/torvalds/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * NXP PTN3460 DP/LVDS bridge driver
  *
  * Copyright (C) 2013 Google, Inc.
  */

 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_edid.h>
 #include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>

 #define PTN3460_EDID_ADDR			0x0
 #define PTN3460_EDID_EMULATION_ADDR		0x84
 #define PTN3460_EDID_ENABLE_EMULATION		0
 #define PTN3460_EDID_EMULATION_SELECTION	1
 #define PTN3460_EDID_SRAM_LOAD_ADDR		0x85

 struct ptn3460_bridge {
 	struct drm_connector connector;
 	struct i2c_client *client;
 	struct drm_bridge bridge;
 	struct edid *edid;
 	struct drm_panel *panel;
 	struct gpio_desc *gpio_pd_n;
 	struct gpio_desc *gpio_rst_n;
 	u32 edid_emulation;
 	bool enabled;
 };

 static inline struct ptn3460_bridge *
 		bridge_to_ptn3460(struct drm_bridge *bridge)
 {
 	return container_of(bridge, struct ptn3460_bridge, bridge);
 }

 static inline struct ptn3460_bridge *
 		connector_to_ptn3460(struct drm_connector *connector)
 {
 	return container_of(connector, struct ptn3460_bridge, connector);
 }

 static int ptn3460_read_bytes(struct ptn3460_bridge *ptn_bridge, char addr,
 		u8 *buf, int len)
 {
 	int ret;

 	ret = i2c_master_send(ptn_bridge->client, &addr, 1);
 	if (ret <= 0) {
 		DRM_ERROR("Failed to send i2c command, ret=%d\n", ret);
 		return ret;
 	}

 	ret = i2c_master_recv(ptn_bridge->client, buf, len);
 	if (ret <= 0) {
 		DRM_ERROR("Failed to recv i2c data, ret=%d\n", ret);
 		return ret;
 	}

 	return 0;
 }

 static int ptn3460_write_byte(struct ptn3460_bridge *ptn_bridge, char addr,
 		char val)
 {
 	int ret;
 	char buf[2];

 	buf[0] = addr;
 	buf[1] = val;

 	ret = i2c_master_send(ptn_bridge->client, buf, ARRAY_SIZE(buf));
 	if (ret <= 0) {
 		DRM_ERROR("Failed to send i2c command, ret=%d\n", ret);
 		return ret;
 	}

 	return 0;
 }

 static int ptn3460_select_edid(struct ptn3460_bridge *ptn_bridge)
 {
 	int ret;
 	char val;

 	/* Load the selected edid into SRAM (accessed at PTN3460_EDID_ADDR) */
 	ret = ptn3460_write_byte(ptn_bridge, PTN3460_EDID_SRAM_LOAD_ADDR,
 			ptn_bridge->edid_emulation);
 	if (ret) {
 		DRM_ERROR("Failed to transfer EDID to sram, ret=%d\n", ret);
 		return ret;
 	}

 	/* Enable EDID emulation and select the desired EDID */
 	val = 1 << PTN3460_EDID_ENABLE_EMULATION |
 		ptn_bridge->edid_emulation << PTN3460_EDID_EMULATION_SELECTION;

 	ret = ptn3460_write_byte(ptn_bridge, PTN3460_EDID_EMULATION_ADDR, val);
 	if (ret) {
 		DRM_ERROR("Failed to write EDID value, ret=%d\n", ret);
 		return ret;
 	}

 	return 0;
 }

 static void ptn3460_pre_enable(struct drm_bridge *bridge)
 {
 	struct ptn3460_bridge *ptn_bridge = bridge_to_ptn3460(bridge);
 	int ret;

 	if (ptn_bridge->enabled)
 		return;

 	gpiod_set_value(ptn_bridge->gpio_pd_n, 1);

 	gpiod_set_value(ptn_bridge->gpio_rst_n, 0);
 	usleep_range(10, 20);
 	gpiod_set_value(ptn_bridge->gpio_rst_n, 1);

 	if (drm_panel_prepare(ptn_bridge->panel)) {
 		DRM_ERROR("failed to prepare panel\n");
 		return;
 	}

 	/*
 	 * There's a bug in the PTN chip where it falsely asserts hotplug before
 	 * it is fully functional. We're forced to wait for the maximum start up
 	 * time specified in the chip's datasheet to make sure we're really up.
 	 */
 	msleep(90);

 	ret = ptn3460_select_edid(ptn_bridge);
 	if (ret)
 		DRM_ERROR("Select EDID failed ret=%d\n", ret);

 	ptn_bridge->enabled = true;
 }

 static void ptn3460_enable(struct drm_bridge *bridge)
 {
 	struct ptn3460_bridge *ptn_bridge = bridge_to_ptn3460(bridge);

 	if (drm_panel_enable(ptn_bridge->panel)) {
 		DRM_ERROR("failed to enable panel\n");
 		return;
 	}
 }

 static void ptn3460_disable(struct drm_bridge *bridge)
 {
 	struct ptn3460_bridge *ptn_bridge = bridge_to_ptn3460(bridge);

 	if (!ptn_bridge->enabled)
 		return;

 	ptn_bridge->enabled = false;

 	if (drm_panel_disable(ptn_bridge->panel)) {
 		DRM_ERROR("failed to disable panel\n");
 		return;
 	}

 	gpiod_set_value(ptn_bridge->gpio_rst_n, 1);
 	gpiod_set_value(ptn_bridge->gpio_pd_n, 0);
 }

 static void ptn3460_post_disable(struct drm_bridge *bridge)
 {
 	struct ptn3460_bridge *ptn_bridge = bridge_to_ptn3460(bridge);

 	if (drm_panel_unprepare(ptn_bridge->panel)) {
 		DRM_ERROR("failed to unprepare panel\n");
 		return;
 	}
 }

 static int ptn3460_get_modes(struct drm_connector *connector)
 {
 	struct ptn3460_bridge *ptn_bridge;
 	u8 *edid;
 	int ret, num_modes = 0;
 	bool power_off;

 	ptn_bridge = connector_to_ptn3460(connector);

 	if (ptn_bridge->edid)
 		return drm_add_edid_modes(connector, ptn_bridge->edid);

 	power_off = !ptn_bridge->enabled;
 	ptn3460_pre_enable(&ptn_bridge->bridge);

 	edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
 	if (!edid) {
 		DRM_ERROR("Failed to allocate EDID\n");
 		return 0;
 	}

 	ret = ptn3460_read_bytes(ptn_bridge, PTN3460_EDID_ADDR, edid,
 			EDID_LENGTH);
 	if (ret) {
 		kfree(edid);
 		goto out;
 	}

 	ptn_bridge->edid = (struct edid *)edid;
 	drm_connector_update_edid_property(connector, ptn_bridge->edid);

 	num_modes = drm_add_edid_modes(connector, ptn_bridge->edid);

 out:
 	if (power_off)
 		ptn3460_disable(&ptn_bridge->bridge);

 	return num_modes;
 }

 static const struct drm_connector_helper_funcs ptn3460_connector_helper_funcs = {
 	.get_modes = ptn3460_get_modes,
 };

 static const struct drm_connector_funcs ptn3460_connector_funcs = {
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.destroy = drm_connector_cleanup,
 	.reset = drm_atomic_helper_connector_reset,
 	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 };

 static int ptn3460_bridge_attach(struct drm_bridge *bridge)
 {
 	struct ptn3460_bridge *ptn_bridge = bridge_to_ptn3460(bridge);
 	int ret;

 	if (!bridge->encoder) {
 		DRM_ERROR("Parent encoder object not found");
 		return -ENODEV;
 	}

 	ptn_bridge->connector.polled = DRM_CONNECTOR_POLL_HPD;
 	ret = drm_connector_init(bridge->dev, &ptn_bridge->connector,
 			&ptn3460_connector_funcs, DRM_MODE_CONNECTOR_LVDS);
 	if (ret) {
 		DRM_ERROR("Failed to initialize connector with drm\n");
 		return ret;
 	}
 	drm_connector_helper_add(&ptn_bridge->connector,
 					&ptn3460_connector_helper_funcs);
 	drm_connector_register(&ptn_bridge->connector);
 	drm_connector_attach_encoder(&ptn_bridge->connector,
 							bridge->encoder);

 	if (ptn_bridge->panel)
 		drm_panel_attach(ptn_bridge->panel, &ptn_bridge->connector);

 	drm_helper_hpd_irq_event(ptn_bridge->connector.dev);

 	return ret;
 }

 static const struct drm_bridge_funcs ptn3460_bridge_funcs = {
 	.pre_enable = ptn3460_pre_enable,
 	.enable = ptn3460_enable,
 	.disable = ptn3460_disable,
 	.post_disable = ptn3460_post_disable,
 	.attach = ptn3460_bridge_attach,
 };

 static int ptn3460_probe(struct i2c_client *client,
 				const struct i2c_device_id *id)
 {
 	struct device *dev = &client->dev;
 	struct ptn3460_bridge *ptn_bridge;
 	int ret;

 	ptn_bridge = devm_kzalloc(dev, sizeof(*ptn_bridge), GFP_KERNEL);
 	if (!ptn_bridge) {
 		return -ENOMEM;
 	}

 	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0, &ptn_bridge->panel, NULL);
 	if (ret)
 		return ret;

 	ptn_bridge->client = client;

 	ptn_bridge->gpio_pd_n = devm_gpiod_get(&client->dev, "powerdown",
 					       GPIOD_OUT_HIGH);
 	if (IS_ERR(ptn_bridge->gpio_pd_n)) {
 		ret = PTR_ERR(ptn_bridge->gpio_pd_n);
 		dev_err(dev, "cannot get gpio_pd_n %d\n", ret);
 		return ret;
 	}

 	/*
 	 * Request the reset pin low to avoid the bridge being
 	 * initialized prematurely
 	 */
 	ptn_bridge->gpio_rst_n = devm_gpiod_get(&client->dev, "reset",
 						GPIOD_OUT_LOW);
 	if (IS_ERR(ptn_bridge->gpio_rst_n)) {
 		ret = PTR_ERR(ptn_bridge->gpio_rst_n);
 		DRM_ERROR("cannot get gpio_rst_n %d\n", ret);
 		return ret;
 	}

 	ret = of_property_read_u32(dev->of_node, "edid-emulation",
 			&ptn_bridge->edid_emulation);
 	if (ret) {
 		dev_err(dev, "Can't read EDID emulation value\n");
 		return ret;
 	}

 	ptn_bridge->bridge.funcs = &ptn3460_bridge_funcs;
 	ptn_bridge->bridge.of_node = dev->of_node;
 	drm_bridge_add(&ptn_bridge->bridge);

 	i2c_set_clientdata(client, ptn_bridge);

 	return 0;
 }

 static int ptn3460_remove(struct i2c_client *client)
 {
 	struct ptn3460_bridge *ptn_bridge = i2c_get_clientdata(client);

 	drm_bridge_remove(&ptn_bridge->bridge);

 	return 0;
 }

 static const struct i2c_device_id ptn3460_i2c_table[] = {
 	{"ptn3460", 0},
 	{},
 };
 MODULE_DEVICE_TABLE(i2c, ptn3460_i2c_table);

 static const struct of_device_id ptn3460_match[] = {
 	{ .compatible = "nxp,ptn3460" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, ptn3460_match);

 static struct i2c_driver ptn3460_driver = {
 	.id_table	= ptn3460_i2c_table,
 	.probe		= ptn3460_probe,
 	.remove		= ptn3460_remove,
 	.driver		= {
 		.name	= "nxp,ptn3460",
 		.of_match_table = ptn3460_match,
 	},
 };
 module_i2c_driver(ptn3460_driver);

 MODULE_AUTHOR("Sean Paul <seanpaul@chromium.org>");
 MODULE_DESCRIPTION("NXP ptn3460 eDP-LVDS converter driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* NXP PTN3460 DP/LVDS bridge driver
	*
	* Copyright (C) 2013 Google, Inc.
	*/

	#include <linux/delay.h>
	#include <linux/gpio/consumer.h>
	#include <linux/i2c.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <drm/drm_atomic_helper.h>
	#include <drm/drm_bridge.h>
	#include <drm/drm_crtc.h>
	#include <drm/drm_edid.h>
	#include <drm/drm_of.h>
	#include <drm/drm_panel.h>
	#include <drm/drm_print.h>
	#include <drm/drm_probe_helper.h>

	#define PTN3460_EDID_ADDR 0x0
	#define PTN3460_EDID_EMULATION_ADDR 0x84
	#define PTN3460_EDID_ENABLE_EMULATION 0
	#define PTN3460_EDID_EMULATION_SELECTION 1
	#define PTN3460_EDID_SRAM_LOAD_ADDR 0x85

	struct ptn3460_bridge {
	struct drm_connector connector;
	struct i2c_client *client;
	struct drm_bridge bridge;
	struct edid *edid;
	struct drm_panel *panel;
	struct gpio_desc *gpio_pd_n;
	struct gpio_desc *gpio_rst_n;
	u32 edid_emulation;
	bool enabled;
	};

	static inline struct ptn3460_bridge *
	bridge_to_ptn3460(struct drm_bridge *bridge)
	{
	return container_of(bridge, struct ptn3460_bridge, bridge);
	}

	static inline struct ptn3460_bridge *
	connector_to_ptn3460(struct drm_connector *connector)
	{
	return container_of(connector, struct ptn3460_bridge, connector);
	}

	static int ptn3460_read_bytes(struct ptn3460_bridge *ptn_bridge, char addr,
	u8 *buf, int len)
	{
	int ret;

	ret = i2c_master_send(ptn_bridge->client, &addr, 1);
	if (ret <= 0) {
	DRM_ERROR("Failed to send i2c command, ret=%d\n", ret);
	return ret;
	}

	ret = i2c_master_recv(ptn_bridge->client, buf, len);
	if (ret <= 0) {
	DRM_ERROR("Failed to recv i2c data, ret=%d\n", ret);
	return ret;
	}

	return 0;
	}

	static int ptn3460_write_byte(struct ptn3460_bridge *ptn_bridge, char addr,
	char val)
	{
	int ret;
	char buf[2];

	buf[0] = addr;
	buf[1] = val;

	ret = i2c_master_send(ptn_bridge->client, buf, ARRAY_SIZE(buf));
	if (ret <= 0) {
	DRM_ERROR("Failed to send i2c command, ret=%d\n", ret);
	return ret;
	}

	return 0;
	}

	static int ptn3460_select_edid(struct ptn3460_bridge *ptn_bridge)
	{
	int ret;
	char val;

	/* Load the selected edid into SRAM (accessed at PTN3460_EDID_ADDR) */
	ret = ptn3460_write_byte(ptn_bridge, PTN3460_EDID_SRAM_LOAD_ADDR,
	ptn_bridge->edid_emulation);
	if (ret) {
	DRM_ERROR("Failed to transfer EDID to sram, ret=%d\n", ret);
	return ret;
	}

	/* Enable EDID emulation and select the desired EDID */
	val = 1 << PTN3460_EDID_ENABLE_EMULATION \|
	ptn_bridge->edid_emulation << PTN3460_EDID_EMULATION_SELECTION;

	ret = ptn3460_write_byte(ptn_bridge, PTN3460_EDID_EMULATION_ADDR, val);
	if (ret) {
	DRM_ERROR("Failed to write EDID value, ret=%d\n", ret);
	return ret;
	}

	return 0;
	}

	static void ptn3460_pre_enable(struct drm_bridge *bridge)
	{
	struct ptn3460_bridge *ptn_bridge = bridge_to_ptn3460(bridge);
	int ret;

	if (ptn_bridge->enabled)
	return;

	gpiod_set_value(ptn_bridge->gpio_pd_n, 1);

	gpiod_set_value(ptn_bridge->gpio_rst_n, 0);
	usleep_range(10, 20);
	gpiod_set_value(ptn_bridge->gpio_rst_n, 1);

	if (drm_panel_prepare(ptn_bridge->panel)) {
	DRM_ERROR("failed to prepare panel\n");
	return;
	}

	/*
	* There's a bug in the PTN chip where it falsely asserts hotplug before
	* it is fully functional. We're forced to wait for the maximum start up
	* time specified in the chip's datasheet to make sure we're really up.
	*/
	msleep(90);

	ret = ptn3460_select_edid(ptn_bridge);
	if (ret)
	DRM_ERROR("Select EDID failed ret=%d\n", ret);

	ptn_bridge->enabled = true;
	}

	static void ptn3460_enable(struct drm_bridge *bridge)
	{
	struct ptn3460_bridge *ptn_bridge = bridge_to_ptn3460(bridge);

	if (drm_panel_enable(ptn_bridge->panel)) {
	DRM_ERROR("failed to enable panel\n");
	return;
	}
	}

	static void ptn3460_disable(struct drm_bridge *bridge)
	{
	struct ptn3460_bridge *ptn_bridge = bridge_to_ptn3460(bridge);

	if (!ptn_bridge->enabled)
	return;

	ptn_bridge->enabled = false;

	if (drm_panel_disable(ptn_bridge->panel)) {
	DRM_ERROR("failed to disable panel\n");
	return;
	}

	gpiod_set_value(ptn_bridge->gpio_rst_n, 1);
	gpiod_set_value(ptn_bridge->gpio_pd_n, 0);
	}

	static void ptn3460_post_disable(struct drm_bridge *bridge)
	{
	struct ptn3460_bridge *ptn_bridge = bridge_to_ptn3460(bridge);

	if (drm_panel_unprepare(ptn_bridge->panel)) {
	DRM_ERROR("failed to unprepare panel\n");
	return;
	}
	}

	static int ptn3460_get_modes(struct drm_connector *connector)
	{
	struct ptn3460_bridge *ptn_bridge;
	u8 *edid;
	int ret, num_modes = 0;
	bool power_off;

	ptn_bridge = connector_to_ptn3460(connector);

	if (ptn_bridge->edid)
	return drm_add_edid_modes(connector, ptn_bridge->edid);

	power_off = !ptn_bridge->enabled;
	ptn3460_pre_enable(&ptn_bridge->bridge);

	edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
	if (!edid) {
	DRM_ERROR("Failed to allocate EDID\n");
	return 0;
	}

	ret = ptn3460_read_bytes(ptn_bridge, PTN3460_EDID_ADDR, edid,
	EDID_LENGTH);
	if (ret) {
	kfree(edid);
	goto out;
	}

	ptn_bridge->edid = (struct edid *)edid;
	drm_connector_update_edid_property(connector, ptn_bridge->edid);

	num_modes = drm_add_edid_modes(connector, ptn_bridge->edid);

	out:
	if (power_off)
	ptn3460_disable(&ptn_bridge->bridge);

	return num_modes;
	}

	static const struct drm_connector_helper_funcs ptn3460_connector_helper_funcs = {
	.get_modes = ptn3460_get_modes,
	};

	static const struct drm_connector_funcs ptn3460_connector_funcs = {
	.fill_modes = drm_helper_probe_single_connector_modes,
	.destroy = drm_connector_cleanup,
	.reset = drm_atomic_helper_connector_reset,
	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
	};

	static int ptn3460_bridge_attach(struct drm_bridge *bridge)
	{
	struct ptn3460_bridge *ptn_bridge = bridge_to_ptn3460(bridge);
	int ret;

	if (!bridge->encoder) {
	DRM_ERROR("Parent encoder object not found");
	return -ENODEV;
	}

	ptn_bridge->connector.polled = DRM_CONNECTOR_POLL_HPD;
	ret = drm_connector_init(bridge->dev, &ptn_bridge->connector,
	&ptn3460_connector_funcs, DRM_MODE_CONNECTOR_LVDS);
	if (ret) {
	DRM_ERROR("Failed to initialize connector with drm\n");
	return ret;
	}
	drm_connector_helper_add(&ptn_bridge->connector,
	&ptn3460_connector_helper_funcs);
	drm_connector_register(&ptn_bridge->connector);
	drm_connector_attach_encoder(&ptn_bridge->connector,
	bridge->encoder);

	if (ptn_bridge->panel)
	drm_panel_attach(ptn_bridge->panel, &ptn_bridge->connector);

	drm_helper_hpd_irq_event(ptn_bridge->connector.dev);

	return ret;
	}

	static const struct drm_bridge_funcs ptn3460_bridge_funcs = {
	.pre_enable = ptn3460_pre_enable,
	.enable = ptn3460_enable,
	.disable = ptn3460_disable,
	.post_disable = ptn3460_post_disable,
	.attach = ptn3460_bridge_attach,
	};

	static int ptn3460_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct device *dev = &client->dev;
	struct ptn3460_bridge *ptn_bridge;
	int ret;

	ptn_bridge = devm_kzalloc(dev, sizeof(*ptn_bridge), GFP_KERNEL);
	if (!ptn_bridge) {
	return -ENOMEM;
	}

	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0, &ptn_bridge->panel, NULL);
	if (ret)
	return ret;

	ptn_bridge->client = client;

	ptn_bridge->gpio_pd_n = devm_gpiod_get(&client->dev, "powerdown",
	GPIOD_OUT_HIGH);
	if (IS_ERR(ptn_bridge->gpio_pd_n)) {
	ret = PTR_ERR(ptn_bridge->gpio_pd_n);
	dev_err(dev, "cannot get gpio_pd_n %d\n", ret);
	return ret;
	}

	/*
	* Request the reset pin low to avoid the bridge being
	* initialized prematurely
	*/
	ptn_bridge->gpio_rst_n = devm_gpiod_get(&client->dev, "reset",
	GPIOD_OUT_LOW);
	if (IS_ERR(ptn_bridge->gpio_rst_n)) {
	ret = PTR_ERR(ptn_bridge->gpio_rst_n);
	DRM_ERROR("cannot get gpio_rst_n %d\n", ret);
	return ret;
	}

	ret = of_property_read_u32(dev->of_node, "edid-emulation",
	&ptn_bridge->edid_emulation);
	if (ret) {
	dev_err(dev, "Can't read EDID emulation value\n");
	return ret;
	}

	ptn_bridge->bridge.funcs = &ptn3460_bridge_funcs;
	ptn_bridge->bridge.of_node = dev->of_node;
	drm_bridge_add(&ptn_bridge->bridge);

	i2c_set_clientdata(client, ptn_bridge);

	return 0;
	}

	static int ptn3460_remove(struct i2c_client *client)
	{
	struct ptn3460_bridge *ptn_bridge = i2c_get_clientdata(client);

	drm_bridge_remove(&ptn_bridge->bridge);

	return 0;
	}

	static const struct i2c_device_id ptn3460_i2c_table[] = {
	{"ptn3460", 0},
	{},
	};
	MODULE_DEVICE_TABLE(i2c, ptn3460_i2c_table);

	static const struct of_device_id ptn3460_match[] = {
	{ .compatible = "nxp,ptn3460" },
	{},
	};
	MODULE_DEVICE_TABLE(of, ptn3460_match);

	static struct i2c_driver ptn3460_driver = {
	.id_table = ptn3460_i2c_table,
	.probe = ptn3460_probe,
	.remove = ptn3460_remove,
	.driver = {
	.name = "nxp,ptn3460",
	.of_match_table = ptn3460_match,
	},
	};
	module_i2c_driver(ptn3460_driver);

	MODULE_AUTHOR("Sean Paul <seanpaul@chromium.org>");
	MODULE_DESCRIPTION("NXP ptn3460 eDP-LVDS converter driver");
	MODULE_LICENSE("GPL v2");