debug lk

hc

2024-02-20 e636c8d336489bf3eed5878299e6cc045bbad077

 kernel/drivers/input/touchscreen/eeti_ts.c
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@@ -1,3 +1,4 @@
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+// SPDX-License-Identifier: GPL-2.0-or-later
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 /*
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  * Touch Screen driver for EETI's I2C connected touch screen panels
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  *   Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>
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@@ -8,20 +9,6 @@
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  * Based on migor_ts.c
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  *   Copyright (c) 2008 Magnus Damm
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  *   Copyright (c) 2007 Ujjwal Pande <ujjwal@kenati.com>
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- *
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- * This file is free software; you can redistribute it and/or
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- * modify it under the terms of the GNU  General Public
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- * License as published by the Free Software Foundation; either
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- * version 2 of the License, or (at your option) any later version.
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- *
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- * This file is distributed in the hope that it will be useful,
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- * but WITHOUT ANY WARRANTY; without even the implied warranty of
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- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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- *  General Public License for more details.
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- *
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- * You should have received a copy of the GNU General Public
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- * License along with this library; if not, write to the Free Software
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- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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  */
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 #include <linux/module.h>
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@@ -41,6 +28,7 @@
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 	struct input_dev *input;
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 	struct gpio_desc *attn_gpio;
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 	struct touchscreen_properties props;
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+	struct mutex mutex;
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 	bool running;
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 };
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34
 
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@@ -75,42 +63,80 @@
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 	input_sync(eeti->input);
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 }
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+static int eeti_ts_read(struct eeti_ts *eeti)
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+{
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+	int len, error;
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+	char buf[6];
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+
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+	len = i2c_master_recv(eeti->client, buf, sizeof(buf));
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+	if (len != sizeof(buf)) {
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+		error = len < 0 ? len : -EIO;
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+		dev_err(&eeti->client->dev,
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+			"failed to read touchscreen data: %d\n",
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+			error);
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+		return error;
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+	}
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+
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+	/* Motion packet */
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+	if (buf[0] & 0x80)
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+		eeti_ts_report_event(eeti, buf);
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+
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+	return 0;
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+}
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+
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 static irqreturn_t eeti_ts_isr(int irq, void *dev_id)
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 {
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 	struct eeti_ts *eeti = dev_id;
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-	int len;
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 	int error;
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-	char buf[6];
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+
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+	mutex_lock(&eeti->mutex);
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 	do {
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-		len = i2c_master_recv(eeti->client, buf, sizeof(buf));
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-		if (len != sizeof(buf)) {
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-			error = len < 0 ? len : -EIO;
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-			dev_err(&eeti->client->dev,
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-				"failed to read touchscreen data: %d\n",
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-				error);
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+		/*
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+		 * If we have attention GPIO, trust it. Otherwise we'll read
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+		 * once and exit. We assume that in this case we are using
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+		 * level triggered interrupt and it will get raised again
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+		 * if/when there is more data.
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+		 */
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+		if (eeti->attn_gpio &&
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+		    !gpiod_get_value_cansleep(eeti->attn_gpio)) {
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 			break;
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 		}
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-		if (buf[0] & 0x80) {
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-			/* Motion packet */
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-			eeti_ts_report_event(eeti, buf);
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-		}
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-	} while (eeti->running &&
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-		 eeti->attn_gpio && gpiod_get_value_cansleep(eeti->attn_gpio));
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+		error = eeti_ts_read(eeti);
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+		if (error)
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+			break;
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+	} while (eeti->running && eeti->attn_gpio);
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+
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+	mutex_unlock(&eeti->mutex);
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 	return IRQ_HANDLED;
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 }
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 static void eeti_ts_start(struct eeti_ts *eeti)
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 {
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+	mutex_lock(&eeti->mutex);
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+
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 	eeti->running = true;
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-	wmb();
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 	enable_irq(eeti->client->irq);
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+
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+	/*
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+	 * Kick the controller in case we are using edge interrupt and
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+	 * we missed our edge while interrupt was disabled. We expect
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+	 * the attention GPIO to be wired in this case.
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+	 */
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+	if (eeti->attn_gpio && gpiod_get_value_cansleep(eeti->attn_gpio))
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+		eeti_ts_read(eeti);
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+
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+	mutex_unlock(&eeti->mutex);
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 }
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 static void eeti_ts_stop(struct eeti_ts *eeti)
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 {
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+	/*
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+	 * Not locking here, just setting a flag and expect that the
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+	 * interrupt thread will notice the flag eventually.
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+	 */
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 	eeti->running = false;
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 	wmb();
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 	disable_irq(eeti->client->irq);
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@@ -153,6 +179,8 @@
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 		return -ENOMEM;
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 	}
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+	mutex_init(&eeti->mutex);
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+
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 	input = devm_input_allocate_device(dev);
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 	if (!input) {
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 		dev_err(dev, "Failed to allocate input device.\n");