iio: proximity: isl29501: Fix return type of isl29501_register_writegrafted

isl29501_register_write() was returning a u32 instead of an int.
Since the function returns negative error codes (such as -ERANGE or
return values from i2c_smbus_write_byte_data()), returning an unsigned
integer type prevents callers from correctly checking for negative error
conditions.

Fix this by changing the function return type from u32 to int.

This was found through manual code review.

Fixes: 1c28799257bc ("iio: light: isl29501: Add support for the ISL29501 ToF sensor.")
Signed-off-by: Salah Triki <salah.triki@gmail.com>
Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

1 files changed, 196 insertions, 0 deletions

diff --git a/drivers/input/misc/ibm-panel.c b/drivers/input/misc/ibm-panel.c
new file mode 100644
index 000000000..aa48f62d7
--- /dev/null
+++ b/drivers/input/misc/ibm-panel.c
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) IBM Corporation 2020
+ */
+
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/limits.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/spinlock.h>
+
+#define DEVICE_NAME		"ibm-panel"
+#define PANEL_KEYCODES_COUNT	3
+
+struct ibm_panel {
+	u8 idx;
+	u8 command[11];
+	u32 keycodes[PANEL_KEYCODES_COUNT];
+	spinlock_t lock;	/* protects writes to idx and command */
+	struct input_dev *input;
+};
+
+static u8 ibm_panel_calculate_checksum(struct ibm_panel *panel)
+{
+	u8 chksum;
+	u16 sum = 0;
+	unsigned int i;
+
+	for (i = 0; i < sizeof(panel->command) - 1; ++i) {
+		sum += panel->command[i];
+		if (sum & 0xff00) {
+			sum &= 0xff;
+			sum++;
+		}
+	}
+
+	chksum = sum & 0xff;
+	chksum = ~chksum;
+	chksum++;
+
+	return chksum;
+}
+
+static void ibm_panel_process_command(struct ibm_panel *panel)
+{
+	u8 button;
+	u8 chksum;
+
+	if (panel->command[0] != 0xff && panel->command[1] != 0xf0) {
+		dev_dbg(&panel->input->dev, "command invalid: %02x %02x\n",
+			panel->command[0], panel->command[1]);
+		return;
+	}
+
+	chksum = ibm_panel_calculate_checksum(panel);
+	if (chksum != panel->command[sizeof(panel->command) - 1]) {
+		dev_dbg(&panel->input->dev,
+			"command failed checksum: %u != %u\n", chksum,
+			panel->command[sizeof(panel->command) - 1]);
+		return;
+	}
+
+	button = panel->command[2] & 0xf;
+	if (button < PANEL_KEYCODES_COUNT) {
+		input_report_key(panel->input, panel->keycodes[button],
+				 !(panel->command[2] & 0x80));
+		input_sync(panel->input);
+	} else {
+		dev_dbg(&panel->input->dev, "unknown button %u\n",
+			button);
+	}
+}
+
+static int ibm_panel_i2c_slave_cb(struct i2c_client *client,
+				  enum i2c_slave_event event, u8 *val)
+{
+	struct ibm_panel *panel = i2c_get_clientdata(client);
+
+	dev_dbg(&panel->input->dev, "event: %u data: %02x\n", event, *val);
+
+	guard(spinlock_irqsave)(&panel->lock);
+
+	switch (event) {
+	case I2C_SLAVE_STOP:
+		if (panel->idx == sizeof(panel->command))
+			ibm_panel_process_command(panel);
+		else
+			dev_dbg(&panel->input->dev,
+				"command incorrect size %u\n", panel->idx);
+		fallthrough;
+	case I2C_SLAVE_WRITE_REQUESTED:
+		panel->idx = 0;
+		break;
+	case I2C_SLAVE_WRITE_RECEIVED:
+		if (panel->idx < sizeof(panel->command))
+			panel->command[panel->idx++] = *val;
+		else
+			/*
+			 * The command is too long and therefore invalid, so set the index
+			 * to it's largest possible value. When a STOP is finally received,
+			 * the command will be rejected upon processing.
+			 */
+			panel->idx = U8_MAX;
+		break;
+	case I2C_SLAVE_READ_REQUESTED:
+	case I2C_SLAVE_READ_PROCESSED:
+		*val = 0xff;
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int ibm_panel_probe(struct i2c_client *client)
+{
+	struct ibm_panel *panel;
+	int i;
+	int error;
+
+	panel = devm_kzalloc(&client->dev, sizeof(*panel), GFP_KERNEL);
+	if (!panel)
+		return -ENOMEM;
+
+	spin_lock_init(&panel->lock);
+
+	panel->input = devm_input_allocate_device(&client->dev);
+	if (!panel->input)
+		return -ENOMEM;
+
+	panel->input->name = client->name;
+	panel->input->id.bustype = BUS_I2C;
+
+	error = device_property_read_u32_array(&client->dev,
+					       "linux,keycodes",
+					       panel->keycodes,
+					       PANEL_KEYCODES_COUNT);
+	if (error) {
+		/*
+		 * Use gamepad buttons as defaults for compatibility with
+		 * existing applications.
+		 */
+		panel->keycodes[0] = BTN_NORTH;
+		panel->keycodes[1] = BTN_SOUTH;
+		panel->keycodes[2] = BTN_SELECT;
+	}
+
+	for (i = 0; i < PANEL_KEYCODES_COUNT; ++i)
+		input_set_capability(panel->input, EV_KEY, panel->keycodes[i]);
+
+	error = input_register_device(panel->input);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to register input device: %d\n", error);
+		return error;
+	}
+
+	i2c_set_clientdata(client, panel);
+	error = i2c_slave_register(client, ibm_panel_i2c_slave_cb);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to register as i2c slave: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static void ibm_panel_remove(struct i2c_client *client)
+{
+	i2c_slave_unregister(client);
+}
+
+static const struct of_device_id ibm_panel_match[] = {
+	{ .compatible = "ibm,op-panel" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ibm_panel_match);
+
+static struct i2c_driver ibm_panel_driver = {
+	.driver = {
+		.name = DEVICE_NAME,
+		.of_match_table = ibm_panel_match,
+	},
+	.probe = ibm_panel_probe,
+	.remove = ibm_panel_remove,
+};
+module_i2c_driver(ibm_panel_driver);
+
+MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
+MODULE_DESCRIPTION("IBM Operation Panel Driver");
+MODULE_LICENSE("GPL");