netfs: zero the tail of a short DIO/unbuffered readgrafted

The buffered read collector zero-fills the tail of a short read that
stops below the inode's i_size (netfs_clear_unread()), so a read that
races an extending write still returns the expected number of bytes.
The non-buffered collector path does no such thing: it just records
how much was transferred.

Add the same zero-fill for the non-buffered case, gated on
NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short
result from it is known to be safe to treat as a hole, as opposed to
NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of
the file and should be reported short as-is. Only CLEAR_TAIL should
zero-fill here; a real EOF must stay a real short read.

No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest,
so this is inert on its own -- a following change teaches cifs to set
it in the one case that needs it.

Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item")
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>
Cc: stable@vger.kernel.org

1 files changed, 365 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/da9034-ts.c b/drivers/input/touchscreen/da9034-ts.c
new file mode 100644
index 000000000..2943f6a58
--- /dev/null
+++ b/drivers/input/touchscreen/da9034-ts.c
@@ -0,0 +1,365 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Touchscreen driver for Dialog Semiconductor DA9034
+ *
+ * Copyright (C) 2006-2008 Marvell International Ltd.
+ *	Fengwei Yin <fengwei.yin@marvell.com>
+ *	Bin Yang  <bin.yang@marvell.com>
+ *	Eric Miao <eric.miao@marvell.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/input.h>
+#include <linux/workqueue.h>
+#include <linux/mfd/da903x.h>
+#include <linux/slab.h>
+
+#define DA9034_MANUAL_CTRL	0x50
+#define DA9034_LDO_ADC_EN	(1 << 4)
+
+#define DA9034_AUTO_CTRL1	0x51
+
+#define DA9034_AUTO_CTRL2	0x52
+#define DA9034_AUTO_TSI_EN	(1 << 3)
+#define DA9034_PEN_DETECT	(1 << 4)
+
+#define DA9034_TSI_CTRL1	0x53
+#define DA9034_TSI_CTRL2	0x54
+#define DA9034_TSI_X_MSB	0x6c
+#define DA9034_TSI_Y_MSB	0x6d
+#define DA9034_TSI_XY_LSB	0x6e
+
+enum {
+	STATE_IDLE,	/* wait for pendown */
+	STATE_BUSY,	/* TSI busy sampling */
+	STATE_STOP,	/* sample available */
+	STATE_WAIT,	/* Wait to start next sample */
+};
+
+enum {
+	EVENT_PEN_DOWN,
+	EVENT_PEN_UP,
+	EVENT_TSI_READY,
+	EVENT_TIMEDOUT,
+};
+
+struct da9034_touch {
+	struct device		*da9034_dev;
+	struct input_dev	*input_dev;
+
+	struct delayed_work	tsi_work;
+	struct notifier_block	notifier;
+
+	int	state;
+
+	int	interval_ms;
+	int	x_inverted;
+	int	y_inverted;
+
+	int	last_x;
+	int	last_y;
+};
+
+static inline int is_pen_down(struct da9034_touch *touch)
+{
+	return da903x_query_status(touch->da9034_dev, DA9034_STATUS_PEN_DOWN);
+}
+
+static inline int detect_pen_down(struct da9034_touch *touch, int on)
+{
+	if (on)
+		return da903x_set_bits(touch->da9034_dev,
+				DA9034_AUTO_CTRL2, DA9034_PEN_DETECT);
+	else
+		return da903x_clr_bits(touch->da9034_dev,
+				DA9034_AUTO_CTRL2, DA9034_PEN_DETECT);
+}
+
+static int read_tsi(struct da9034_touch *touch)
+{
+	uint8_t _x, _y, _v;
+	int ret;
+
+	ret = da903x_read(touch->da9034_dev, DA9034_TSI_X_MSB, &_x);
+	if (ret)
+		return ret;
+
+	ret = da903x_read(touch->da9034_dev, DA9034_TSI_Y_MSB, &_y);
+	if (ret)
+		return ret;
+
+	ret = da903x_read(touch->da9034_dev, DA9034_TSI_XY_LSB, &_v);
+	if (ret)
+		return ret;
+
+	touch->last_x = ((_x << 2) & 0x3fc) | (_v & 0x3);
+	touch->last_y = ((_y << 2) & 0x3fc) | ((_v & 0xc) >> 2);
+
+	return 0;
+}
+
+static inline int start_tsi(struct da9034_touch *touch)
+{
+	return da903x_set_bits(touch->da9034_dev,
+			DA9034_AUTO_CTRL2, DA9034_AUTO_TSI_EN);
+}
+
+static inline int stop_tsi(struct da9034_touch *touch)
+{
+	return da903x_clr_bits(touch->da9034_dev,
+			DA9034_AUTO_CTRL2, DA9034_AUTO_TSI_EN);
+}
+
+static inline void report_pen_down(struct da9034_touch *touch)
+{
+	int x = touch->last_x;
+	int y = touch->last_y;
+
+	x &= 0xfff;
+	if (touch->x_inverted)
+		x = 1024 - x;
+	y &= 0xfff;
+	if (touch->y_inverted)
+		y = 1024 - y;
+
+	input_report_abs(touch->input_dev, ABS_X, x);
+	input_report_abs(touch->input_dev, ABS_Y, y);
+	input_report_key(touch->input_dev, BTN_TOUCH, 1);
+
+	input_sync(touch->input_dev);
+}
+
+static inline void report_pen_up(struct da9034_touch *touch)
+{
+	input_report_key(touch->input_dev, BTN_TOUCH, 0);
+	input_sync(touch->input_dev);
+}
+
+static void da9034_event_handler(struct da9034_touch *touch, int event)
+{
+	int err;
+
+	switch (touch->state) {
+	case STATE_IDLE:
+		if (event != EVENT_PEN_DOWN)
+			break;
+
+		/* Enable auto measurement of the TSI, this will
+		 * automatically disable pen down detection
+		 */
+		err = start_tsi(touch);
+		if (err)
+			goto err_reset;
+
+		touch->state = STATE_BUSY;
+		break;
+
+	case STATE_BUSY:
+		if (event != EVENT_TSI_READY)
+			break;
+
+		err = read_tsi(touch);
+		if (err)
+			goto err_reset;
+
+		/* Disable auto measurement of the TSI, so that
+		 * pen down status will be available
+		 */
+		err = stop_tsi(touch);
+		if (err)
+			goto err_reset;
+
+		touch->state = STATE_STOP;
+
+		/* FIXME: PEN_{UP/DOWN} events are expected to be
+		 * available by stopping TSI, but this is found not
+		 * always true, delay and simulate such an event
+		 * here is more reliable
+		 */
+		mdelay(1);
+		da9034_event_handler(touch,
+				     is_pen_down(touch) ? EVENT_PEN_DOWN :
+							  EVENT_PEN_UP);
+		break;
+
+	case STATE_STOP:
+		if (event == EVENT_PEN_DOWN) {
+			report_pen_down(touch);
+			schedule_delayed_work(&touch->tsi_work,
+				msecs_to_jiffies(touch->interval_ms));
+			touch->state = STATE_WAIT;
+		}
+
+		if (event == EVENT_PEN_UP) {
+			report_pen_up(touch);
+			touch->state = STATE_IDLE;
+		}
+		break;
+
+	case STATE_WAIT:
+		if (event != EVENT_TIMEDOUT)
+			break;
+
+		if (is_pen_down(touch)) {
+			start_tsi(touch);
+			touch->state = STATE_BUSY;
+		} else {
+			report_pen_up(touch);
+			touch->state = STATE_IDLE;
+		}
+		break;
+	}
+	return;
+
+err_reset:
+	touch->state = STATE_IDLE;
+	stop_tsi(touch);
+	detect_pen_down(touch, 1);
+}
+
+static void da9034_tsi_work(struct work_struct *work)
+{
+	struct da9034_touch *touch =
+		container_of(work, struct da9034_touch, tsi_work.work);
+
+	da9034_event_handler(touch, EVENT_TIMEDOUT);
+}
+
+static int da9034_touch_notifier(struct notifier_block *nb,
+				 unsigned long event, void *data)
+{
+	struct da9034_touch *touch =
+		container_of(nb, struct da9034_touch, notifier);
+
+	if (event & DA9034_EVENT_TSI_READY)
+		da9034_event_handler(touch, EVENT_TSI_READY);
+
+	if ((event & DA9034_EVENT_PEN_DOWN) && touch->state == STATE_IDLE)
+		da9034_event_handler(touch, EVENT_PEN_DOWN);
+
+	return 0;
+}
+
+static int da9034_touch_open(struct input_dev *dev)
+{
+	struct da9034_touch *touch = input_get_drvdata(dev);
+	int ret;
+
+	ret = da903x_register_notifier(touch->da9034_dev, &touch->notifier,
+			DA9034_EVENT_PEN_DOWN | DA9034_EVENT_TSI_READY);
+	if (ret)
+		return -EBUSY;
+
+	/* Enable ADC LDO */
+	ret = da903x_set_bits(touch->da9034_dev,
+			DA9034_MANUAL_CTRL, DA9034_LDO_ADC_EN);
+	if (ret)
+		return ret;
+
+	/* TSI_DELAY: 3 slots, TSI_SKIP: 3 slots */
+	ret = da903x_write(touch->da9034_dev, DA9034_TSI_CTRL1, 0x1b);
+	if (ret)
+		return ret;
+
+	ret = da903x_write(touch->da9034_dev, DA9034_TSI_CTRL2, 0x00);
+	if (ret)
+		return ret;
+
+	touch->state = STATE_IDLE;
+	detect_pen_down(touch, 1);
+
+	return 0;
+}
+
+static void da9034_touch_close(struct input_dev *dev)
+{
+	struct da9034_touch *touch = input_get_drvdata(dev);
+
+	da903x_unregister_notifier(touch->da9034_dev, &touch->notifier,
+			DA9034_EVENT_PEN_DOWN | DA9034_EVENT_TSI_READY);
+
+	cancel_delayed_work_sync(&touch->tsi_work);
+
+	touch->state = STATE_IDLE;
+	stop_tsi(touch);
+	detect_pen_down(touch, 0);
+
+	/* Disable ADC LDO */
+	da903x_clr_bits(touch->da9034_dev,
+			DA9034_MANUAL_CTRL, DA9034_LDO_ADC_EN);
+}
+
+
+static int da9034_touch_probe(struct platform_device *pdev)
+{
+	struct da9034_touch_pdata *pdata = dev_get_platdata(&pdev->dev);
+	struct da9034_touch *touch;
+	struct input_dev *input_dev;
+	int error;
+
+	touch = devm_kzalloc(&pdev->dev, sizeof(struct da9034_touch),
+			     GFP_KERNEL);
+	if (!touch) {
+		dev_err(&pdev->dev, "failed to allocate driver data\n");
+		return -ENOMEM;
+	}
+
+	touch->da9034_dev = pdev->dev.parent;
+
+	if (pdata) {
+		touch->interval_ms	= pdata->interval_ms;
+		touch->x_inverted	= pdata->x_inverted;
+		touch->y_inverted	= pdata->y_inverted;
+	} else {
+		/* fallback into default */
+		touch->interval_ms	= 10;
+	}
+
+	INIT_DELAYED_WORK(&touch->tsi_work, da9034_tsi_work);
+	touch->notifier.notifier_call = da9034_touch_notifier;
+
+	input_dev = devm_input_allocate_device(&pdev->dev);
+	if (!input_dev) {
+		dev_err(&pdev->dev, "failed to allocate input device\n");
+		return -ENOMEM;
+	}
+
+	input_dev->name		= pdev->name;
+	input_dev->open		= da9034_touch_open;
+	input_dev->close	= da9034_touch_close;
+	input_dev->dev.parent	= &pdev->dev;
+
+	__set_bit(EV_ABS, input_dev->evbit);
+	__set_bit(ABS_X, input_dev->absbit);
+	__set_bit(ABS_Y, input_dev->absbit);
+	input_set_abs_params(input_dev, ABS_X, 0, 1023, 0, 0);
+	input_set_abs_params(input_dev, ABS_Y, 0, 1023, 0, 0);
+
+	__set_bit(EV_KEY, input_dev->evbit);
+	__set_bit(BTN_TOUCH, input_dev->keybit);
+
+	touch->input_dev = input_dev;
+	input_set_drvdata(input_dev, touch);
+
+	error = input_register_device(input_dev);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static struct platform_driver da9034_touch_driver = {
+	.driver	= {
+		.name	= "da9034-touch",
+	},
+	.probe		= da9034_touch_probe,
+};
+module_platform_driver(da9034_touch_driver);
+
+MODULE_DESCRIPTION("Touchscreen driver for Dialog Semiconductor DA9034");
+MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>, Bin Yang <bin.yang@marvell.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:da9034-touch");