iio: proximity: vl53l0x-i2c: claim direct mode for raw readsgrafted

vl53l0x_read_raw() starts a single-shot ranging measurement and reads
back the result. Once the triggered buffer is enabled the sensor runs in
continuous mode and its data-ready interrupt is routed to the trigger,
so a concurrent in_distance_raw read disturbs the streaming setup and
never gets its completion, returning -ETIMEDOUT.

The original submission claimed direct mode here, but it was dropped
during review because the driver had no buffer support at the time [1].
Continuous (buffered) mode was later added without restoring the
claim [2], reintroducing the conflict.

Reject direct reads while buffered capture is active by claiming direct
mode around the measurement, as the vl53l1x sibling already does.

Fixes: 762186c6e7b1 ("iio: proximity: vl53l0x-i2c: Added continuous mode support")
Link: https://lore.kernel.org/linux-iio/20180911160300.GA9212@himanshu-Vostro-3559/ [1]
Link: https://lore.kernel.org/linux-iio/20240909101508.263085-3-abhashkumarjha123@gmail.com/ [2]
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

1 files changed, 166 insertions, 0 deletions

diff --git a/drivers/input/serio/q40kbd.c b/drivers/input/serio/q40kbd.c
new file mode 100644
index 000000000..2f553efbe
--- /dev/null
+++ b/drivers/input/serio/q40kbd.c
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (c) 2000-2001 Vojtech Pavlik
+ *
+ *  Based on the work of:
+ *	Richard Zidlicky <Richard.Zidlicky@stud.informatik.uni-erlangen.de>
+ */
+
+/*
+ * Q40 PS/2 keyboard controller driver for Linux/m68k
+ */
+
+#include <linux/module.h>
+#include <linux/serio.h>
+#include <linux/interrupt.h>
+#include <linux/err.h>
+#include <linux/bitops.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include <asm/io.h>
+#include <linux/uaccess.h>
+#include <asm/q40_master.h>
+#include <asm/irq.h>
+#include <asm/q40ints.h>
+
+#define DRV_NAME	"q40kbd"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION("Q40 PS/2 keyboard controller driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);
+
+struct q40kbd {
+	struct serio *port;
+	spinlock_t lock;
+};
+
+static irqreturn_t q40kbd_interrupt(int irq, void *dev_id)
+{
+	struct q40kbd *q40kbd = dev_id;
+
+	guard(spinlock_irqsave)(&q40kbd->lock);
+
+	if (Q40_IRQ_KEYB_MASK & master_inb(INTERRUPT_REG))
+		serio_interrupt(q40kbd->port, master_inb(KEYCODE_REG), 0);
+
+	master_outb(-1, KEYBOARD_UNLOCK_REG);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * q40kbd_flush() flushes all data that may be in the keyboard buffers
+ */
+
+static void q40kbd_flush(struct q40kbd *q40kbd)
+{
+	int maxread = 100;
+
+	guard(spinlock_irqsave)(&q40kbd->lock);
+
+	while (maxread-- && (Q40_IRQ_KEYB_MASK & master_inb(INTERRUPT_REG)))
+		master_inb(KEYCODE_REG);
+}
+
+static void q40kbd_stop(void)
+{
+	master_outb(0, KEY_IRQ_ENABLE_REG);
+	master_outb(-1, KEYBOARD_UNLOCK_REG);
+}
+
+/*
+ * q40kbd_open() is called when a port is open by the higher layer.
+ * It allocates the interrupt and enables in in the chip.
+ */
+
+static int q40kbd_open(struct serio *port)
+{
+	struct q40kbd *q40kbd = port->port_data;
+
+	q40kbd_flush(q40kbd);
+
+	/* off we go */
+	master_outb(-1, KEYBOARD_UNLOCK_REG);
+	master_outb(1, KEY_IRQ_ENABLE_REG);
+
+	return 0;
+}
+
+static void q40kbd_close(struct serio *port)
+{
+	struct q40kbd *q40kbd = port->port_data;
+
+	q40kbd_stop();
+	q40kbd_flush(q40kbd);
+}
+
+static int q40kbd_probe(struct platform_device *pdev)
+{
+	struct q40kbd *q40kbd;
+	struct serio *port;
+	int error;
+
+	q40kbd = kzalloc_obj(*q40kbd);
+	port = kzalloc_obj(*port);
+	if (!q40kbd || !port) {
+		error = -ENOMEM;
+		goto err_free_mem;
+	}
+
+	q40kbd->port = port;
+	spin_lock_init(&q40kbd->lock);
+
+	port->id.type = SERIO_8042;
+	port->open = q40kbd_open;
+	port->close = q40kbd_close;
+	port->port_data = q40kbd;
+	port->dev.parent = &pdev->dev;
+	strscpy(port->name, "Q40 Kbd Port", sizeof(port->name));
+	strscpy(port->phys, "Q40", sizeof(port->phys));
+
+	q40kbd_stop();
+
+	error = request_irq(Q40_IRQ_KEYBOARD, q40kbd_interrupt, 0,
+			    DRV_NAME, q40kbd);
+	if (error) {
+		dev_err(&pdev->dev, "Can't get irq %d.\n", Q40_IRQ_KEYBOARD);
+		goto err_free_mem;
+	}
+
+	serio_register_port(q40kbd->port);
+
+	platform_set_drvdata(pdev, q40kbd);
+	printk(KERN_INFO "serio: Q40 kbd registered\n");
+
+	return 0;
+
+err_free_mem:
+	kfree(port);
+	kfree(q40kbd);
+	return error;
+}
+
+static void q40kbd_remove(struct platform_device *pdev)
+{
+	struct q40kbd *q40kbd = platform_get_drvdata(pdev);
+
+	/*
+	 * q40kbd_close() will be called as part of unregistering
+	 * and will ensure that IRQ is turned off, so it is safe
+	 * to unregister port first and free IRQ later.
+	 */
+	serio_unregister_port(q40kbd->port);
+	free_irq(Q40_IRQ_KEYBOARD, q40kbd);
+	kfree(q40kbd);
+}
+
+static struct platform_driver q40kbd_driver = {
+	.driver		= {
+		.name	= "q40kbd",
+	},
+	.remove		= q40kbd_remove,
+};
+
+module_platform_driver_probe(q40kbd_driver, q40kbd_probe);