[d-kernel] [PATCH 4/7] input: new driver - serdev-serio

[Alexey Sheplyakov]

From: "Vadim V. Vlasov" <vadim.vlasov на elpitech.ru>

The driver provides serio interface from serial device.
Together with ps2mult driver it enables PS/2 support for
Elpitech boards.

This replaces old tp_serio driver which used i2c transport
and suffered from synchronization loss when PS/2 mouse
is used.

X-feature-Baikal-M
---
 drivers/input/serio/Kconfig        |  11 +++
 drivers/input/serio/Makefile       |   1 +
 drivers/input/serio/serdev-serio.c | 121 +++++++++++++++++++++++++++++
 3 files changed, 133 insertions(+)
 create mode 100644 drivers/input/serio/serdev-serio.c

diff --git a/drivers/input/serio/Kconfig b/drivers/input/serio/Kconfig
index 8e6b8b3ef478..967b5828ac50 100644
--- a/drivers/input/serio/Kconfig
+++ b/drivers/input/serio/Kconfig
@@ -328,4 +328,15 @@ config USERIO
 
 	  If you are unsure, say N.
 
+config SERDEV_SERIO
+	tristate "SERDEV SERIO driver"
+	depends on OF && SERIAL_DEV_BUS
+	help
+	  Say Y here if you have the serial peripherals supporting serio
+	  protocol. E.g. PS/2 line multiplexer like the one present on
+	  TQC boards.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called serdev-serio.
+
 endif
diff --git a/drivers/input/serio/Makefile b/drivers/input/serio/Makefile
index a47319040c19..8f1be3803fd3 100644
--- a/drivers/input/serio/Makefile
+++ b/drivers/input/serio/Makefile
@@ -34,3 +34,4 @@ obj-$(CONFIG_SERIO_SUN4I_PS2)	+= sun4i-ps2.o
 obj-$(CONFIG_SERIO_GPIO_PS2)	+= ps2-gpio.o
 obj-$(CONFIG_SERIO_TPLATFORMS)	+= tp_serio.o
 obj-$(CONFIG_USERIO)		+= userio.o
+obj-$(CONFIG_SERDEV_SERIO)	+= serdev-serio.o
diff --git a/drivers/input/serio/serdev-serio.c b/drivers/input/serio/serdev-serio.c
new file mode 100644
index 000000000000..c2170524d0db
--- /dev/null
+++ b/drivers/input/serio/serdev-serio.c
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Serdev Serio driver
+ *
+ * Copyright (C) 2022 Elpitech
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/serio.h>
+#include <linux/serdev.h>
+
+struct serdev_serio {
+	struct serdev_device *serdev;
+	struct serio *serio;
+};
+
+static int ss_serio_write(struct serio *serio, unsigned char data)
+{
+	struct serdev_serio *ss = serio->port_data;
+	struct serdev_device *serdev = ss->serdev;
+
+	dev_dbg(&serdev->dev, "ss_write: data %02x\n", data);
+	serdev_device_write(serdev, &data, 1, 0);
+
+	return 0;
+}
+
+static int ss_receive_buf(struct serdev_device *serdev,
+			  const unsigned char *buf, size_t count)
+{
+	struct serdev_serio *ss = serdev_device_get_drvdata(serdev);
+	int ret = count;
+
+	dev_dbg(&serdev->dev, "ss_receive: count %d, data %02x\n", (int)count, *buf);
+	while (count--)
+		serio_interrupt(ss->serio, *buf++, 0);
+
+	return ret;
+}
+
+static const struct serdev_device_ops ss_serdev_ops = {
+	.receive_buf    = ss_receive_buf,
+	.write_wakeup   = serdev_device_write_wakeup,
+};
+
+static int ss_probe(struct serdev_device *serdev)
+{
+	struct device *dev = &serdev->dev;
+	struct device_node *node = dev->of_node;
+	struct serdev_serio *ss;
+	struct serio *serio;
+	u32 speed = 0, proto;
+	int ret;
+
+	serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
+	if (!serio)
+		return -ENOMEM;
+
+	ss = devm_kzalloc(dev, sizeof(*ss), GFP_KERNEL);
+	if (!ss)
+		return -ENOMEM;
+	ss->serdev = serdev;
+	ss->serio = serio;
+	ret = of_property_read_u32(node, "protocol", &proto);
+	if (ret < 0) {
+		dev_err(dev, "Can't read protocol property (ret %d)\n", ret);
+		return ret;
+	}
+	of_property_read_u32(node, "current-speed", &speed);
+	serdev_device_set_drvdata(serdev, ss);
+	serdev_device_set_client_ops(serdev, &ss_serdev_ops);
+	ret = serdev_device_open(serdev);
+	if (ret)
+		return ret;
+
+	if (speed)
+		serdev_device_set_baudrate(serdev, speed);
+	serdev_device_set_flow_control(serdev, false);
+
+	serio->port_data = ss;
+	strlcpy(serio->name, "Serdev Serio", sizeof(serio->name));
+	strlcpy(serio->phys, "serio", sizeof(serio->phys));
+	serio->id.type = SERIO_RS232;
+	serio->id.proto = proto;
+	serio->id.id = SERIO_ANY;
+	serio->id.extra = SERIO_ANY;
+	serio->write = ss_serio_write;
+	serio_register_port(serio);
+
+	return 0;
+}
+
+static void ss_remove(struct serdev_device *serdev)
+{
+	struct serdev_serio *ss = serdev_device_get_drvdata(serdev);
+	serdev_device_close(ss->serdev);
+	serio_unregister_port(ss->serio);
+}
+
+static const struct of_device_id ss_of_match[] = {
+	{ .compatible = "serdev,serio" },
+	{},
+};
+
+static struct serdev_device_driver serdev_serio_drv = {
+	.driver		= {
+		.name	= "serdev_serio",
+		.of_match_table = of_match_ptr(ss_of_match),
+	},
+	.probe  = ss_probe,
+	.remove = ss_remove,
+};
+
+module_serdev_device_driver(serdev_serio_drv);
+
+MODULE_AUTHOR("Vadim V. Vlasov <vvv19xx на gmail.com>");
+MODULE_DESCRIPTION("Serdev Serio driver");
+MODULE_LICENSE("GPL");
-- 
2.32.0