Input: add a driver to support Hyper-V synthetic keyboard

Add a new driver to support synthetic keyboard. On the next generation
Hyper-V guest firmware, many legacy devices will not be emulated and this
driver will be required.

I would like to thank Vojtech Pavlik <vojtech@suse.cz> for helping me with the
details of the AT keyboard driver. I would also like to thank
Dan Carpenter <dan.carpenter@oracle.com> and
Dmitry Torokhov <dmitry.torokhov@gmail.com> for their detailed review of this
driver.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/serio/Kconfig

@@ -267,4 +267,14 @@ config SERIO_OLPC_APSP
 	  To compile this driver as a module, choose M here: the module will
 	  be called olpc_apsp.
 
+config HYPERV_KEYBOARD
+	tristate "Microsoft Synthetic Keyboard driver"
+	depends on HYPERV
+	default HYPERV
+	help
+	  Select this option to enable the Hyper-V Keyboard driver.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called hyperv_keyboard.
+
 endif

drivers/input/serio/Makefile

@@ -28,3 +28,4 @@ obj-$(CONFIG_SERIO_ALTERA_PS2)	+= altera_ps2.o
 obj-$(CONFIG_SERIO_ARC_PS2)	+= arc_ps2.o
 obj-$(CONFIG_SERIO_APBPS2)	+= apbps2.o
 obj-$(CONFIG_SERIO_OLPC_APSP)	+= olpc_apsp.o
+obj-$(CONFIG_HYPERV_KEYBOARD)	+= hyperv-keyboard.o

drivers/input/serio/hyperv-keyboard.c

@@ -0,0 +1,437 @@
+/*
+ *  Copyright (c) 2013, Microsoft Corporation.
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms and conditions of the GNU General Public License,
+ *  version 2, as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ *  more details.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/completion.h>
+#include <linux/hyperv.h>
+#include <linux/serio.h>
+#include <linux/slab.h>
+
+/*
+ * Current version 1.0
+ *
+ */
+#define SYNTH_KBD_VERSION_MAJOR 1
+#define SYNTH_KBD_VERSION_MINOR	0
+#define SYNTH_KBD_VERSION		(SYNTH_KBD_VERSION_MINOR | \
+					 (SYNTH_KBD_VERSION_MAJOR << 16))
+
+
+/*
+ * Message types in the synthetic input protocol
+ */
+enum synth_kbd_msg_type {
+	SYNTH_KBD_PROTOCOL_REQUEST = 1,
+	SYNTH_KBD_PROTOCOL_RESPONSE = 2,
+	SYNTH_KBD_EVENT = 3,
+	SYNTH_KBD_LED_INDICATORS = 4,
+};
+
+/*
+ * Basic message structures.
+ */
+struct synth_kbd_msg_hdr {
+	__le32 type;
+};
+
+struct synth_kbd_msg {
+	struct synth_kbd_msg_hdr header;
+	char data[]; /* Enclosed message */
+};
+
+union synth_kbd_version {
+	__le32 version;
+};
+
+/*
+ * Protocol messages
+ */
+struct synth_kbd_protocol_request {
+	struct synth_kbd_msg_hdr header;
+	union synth_kbd_version version_requested;
+};
+
+#define PROTOCOL_ACCEPTED	BIT(0)
+struct synth_kbd_protocol_response {
+	struct synth_kbd_msg_hdr header;
+	__le32 proto_status;
+};
+
+#define IS_UNICODE	BIT(0)
+#define IS_BREAK	BIT(1)
+#define IS_E0		BIT(2)
+#define IS_E1		BIT(3)
+struct synth_kbd_keystroke {
+	struct synth_kbd_msg_hdr header;
+	__le16 make_code;
+	__le16 reserved0;
+	__le32 info; /* Additional information */
+};
+
+
+#define HK_MAXIMUM_MESSAGE_SIZE 256
+
+#define KBD_VSC_SEND_RING_BUFFER_SIZE		(10 * PAGE_SIZE)
+#define KBD_VSC_RECV_RING_BUFFER_SIZE		(10 * PAGE_SIZE)
+
+#define XTKBD_EMUL0     0xe0
+#define XTKBD_EMUL1     0xe1
+#define XTKBD_RELEASE   0x80
+
+
+/*
+ * Represents a keyboard device
+ */
+struct hv_kbd_dev {
+	struct hv_device *hv_dev;
+	struct serio *hv_serio;
+	struct synth_kbd_protocol_request protocol_req;
+	struct synth_kbd_protocol_response protocol_resp;
+	/* Synchronize the request/response if needed */
+	struct completion wait_event;
+	spinlock_t lock; /* protects 'started' field */
+	bool started;
+};
+
+static void hv_kbd_on_receive(struct hv_device *hv_dev,
+			      struct synth_kbd_msg *msg, u32 msg_length)
+{
+	struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
+	struct synth_kbd_keystroke *ks_msg;
+	unsigned long flags;
+	u32 msg_type = __le32_to_cpu(msg->header.type);
+	u32 info;
+	u16 scan_code;
+
+	switch (msg_type) {
+	case SYNTH_KBD_PROTOCOL_RESPONSE:
+		/*
+		 * Validate the information provided by the host.
+		 * If the host is giving us a bogus packet,
+		 * drop the packet (hoping the problem
+		 * goes away).
+		 */
+		if (msg_length < sizeof(struct synth_kbd_protocol_response)) {
+			dev_err(&hv_dev->device,
+				"Illegal protocol response packet (len: %d)\n",
+				msg_length);
+			break;
+		}
+
+		memcpy(&kbd_dev->protocol_resp, msg,
+			sizeof(struct synth_kbd_protocol_response));
+		complete(&kbd_dev->wait_event);
+		break;
+
+	case SYNTH_KBD_EVENT:
+		/*
+		 * Validate the information provided by the host.
+		 * If the host is giving us a bogus packet,
+		 * drop the packet (hoping the problem
+		 * goes away).
+		 */
+		if (msg_length < sizeof(struct  synth_kbd_keystroke)) {
+			dev_err(&hv_dev->device,
+				"Illegal keyboard event packet (len: %d)\n",
+				msg_length);
+			break;
+		}
+
+		ks_msg = (struct synth_kbd_keystroke *)msg;
+		info = __le32_to_cpu(ks_msg->info);
+
+		/*
+		 * Inject the information through the serio interrupt.
+		 */
+		spin_lock_irqsave(&kbd_dev->lock, flags);
+		if (kbd_dev->started) {
+			if (info & IS_E0)
+				serio_interrupt(kbd_dev->hv_serio,
+						XTKBD_EMUL0, 0);
+
+			scan_code = __le16_to_cpu(ks_msg->make_code);
+			if (info & IS_BREAK)
+				scan_code |= XTKBD_RELEASE;
+
+			serio_interrupt(kbd_dev->hv_serio, scan_code, 0);
+		}
+		spin_unlock_irqrestore(&kbd_dev->lock, flags);
+		break;
+
+	default:
+		dev_err(&hv_dev->device,
+			"unhandled message type %d\n", msg_type);
+	}
+}
+
+static void hv_kbd_handle_received_packet(struct hv_device *hv_dev,
+					  struct vmpacket_descriptor *desc,
+					  u32 bytes_recvd,
+					  u64 req_id)
+{
+	struct synth_kbd_msg *msg;
+	u32 msg_sz;
+
+	switch (desc->type) {
+	case VM_PKT_COMP:
+		break;
+
+	case VM_PKT_DATA_INBAND:
+		/*
+		 * We have a packet that has "inband" data. The API used
+		 * for retrieving the packet guarantees that the complete
+		 * packet is read. So, minimally, we should be able to
+		 * parse the payload header safely (assuming that the host
+		 * can be trusted.  Trusting the host seems to be a
+		 * reasonable assumption because in a virtualized
+		 * environment there is not whole lot you can do if you
+		 * don't trust the host.
+		 *
+		 * Nonetheless, let us validate if the host can be trusted
+		 * (in a trivial way).  The interesting aspect of this
+		 * validation is how do you recover if we discover that the
+		 * host is not to be trusted? Simply dropping the packet, I
+		 * don't think is an appropriate recovery.  In the interest
+		 * of failing fast, it may be better to crash the guest.
+		 * For now, I will just drop the packet!
+		 */
+
+		msg_sz = bytes_recvd - (desc->offset8 << 3);
+		if (msg_sz <= sizeof(struct synth_kbd_msg_hdr)) {
+			/*
+			 * Drop the packet and hope
+			 * the problem magically goes away.
+			 */
+			dev_err(&hv_dev->device,
+				"Illegal packet (type: %d, tid: %llx, size: %d)\n",
+				desc->type, req_id, msg_sz);
+			break;
+		}
+
+		msg = (void *)desc + (desc->offset8 << 3);
+		hv_kbd_on_receive(hv_dev, msg, msg_sz);
+		break;
+
+	default:
+		dev_err(&hv_dev->device,
+			"unhandled packet type %d, tid %llx len %d\n",
+			desc->type, req_id, bytes_recvd);
+		break;
+	}
+}
+
+static void hv_kbd_on_channel_callback(void *context)
+{
+	struct hv_device *hv_dev = context;
+	void *buffer;
+	int bufferlen = 0x100; /* Start with sensible size */
+	u32 bytes_recvd;
+	u64 req_id;
+	int error;
+
+	buffer = kmalloc(bufferlen, GFP_ATOMIC);
+	if (!buffer)
+		return;
+
+	while (1) {
+		error = vmbus_recvpacket_raw(hv_dev->channel, buffer, bufferlen,
+					     &bytes_recvd, &req_id);
+		switch (error) {
+		case 0:
+			if (bytes_recvd == 0) {
+				kfree(buffer);
+				return;
+			}
+
+			hv_kbd_handle_received_packet(hv_dev, buffer,
+						      bytes_recvd, req_id);
+			break;
+
+		case -ENOBUFS:
+			kfree(buffer);
+			/* Handle large packet */
+			bufferlen = bytes_recvd;
+			buffer = kmalloc(bytes_recvd, GFP_ATOMIC);
+			if (!buffer)
+				return;
+			break;
+		}
+	}
+}
+
+static int hv_kbd_connect_to_vsp(struct hv_device *hv_dev)
+{
+	struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
+	struct synth_kbd_protocol_request *request;
+	struct synth_kbd_protocol_response *response;
+	u32 proto_status;
+	int error;
+
+	request = &kbd_dev->protocol_req;
+	memset(request, 0, sizeof(struct synth_kbd_protocol_request));
+	request->header.type = __cpu_to_le32(SYNTH_KBD_PROTOCOL_REQUEST);
+	request->version_requested.version = __cpu_to_le32(SYNTH_KBD_VERSION);
+
+	error = vmbus_sendpacket(hv_dev->channel, request,
+				 sizeof(struct synth_kbd_protocol_request),
+				 (unsigned long)request,
+				 VM_PKT_DATA_INBAND,
+				 VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (error)
+		return error;
+
+	if (!wait_for_completion_timeout(&kbd_dev->wait_event, 10 * HZ))
+		return -ETIMEDOUT;
+
+	response = &kbd_dev->protocol_resp;
+	proto_status = __le32_to_cpu(response->proto_status);
+	if (!(proto_status & PROTOCOL_ACCEPTED)) {
+		dev_err(&hv_dev->device,
+			"synth_kbd protocol request failed (version %d)\n",
+		        SYNTH_KBD_VERSION);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int hv_kbd_start(struct serio *serio)
+{
+	struct hv_kbd_dev *kbd_dev = serio->port_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&kbd_dev->lock, flags);
+	kbd_dev->started = true;
+	spin_unlock_irqrestore(&kbd_dev->lock, flags);
+
+	return 0;
+}
+
+static void hv_kbd_stop(struct serio *serio)
+{
+	struct hv_kbd_dev *kbd_dev = serio->port_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&kbd_dev->lock, flags);
+	kbd_dev->started = false;
+	spin_unlock_irqrestore(&kbd_dev->lock, flags);
+}
+
+static int hv_kbd_probe(struct hv_device *hv_dev,
+			const struct hv_vmbus_device_id *dev_id)
+{
+	struct hv_kbd_dev *kbd_dev;
+	struct serio *hv_serio;
+	int error;
+
+	kbd_dev = kzalloc(sizeof(struct hv_kbd_dev), GFP_KERNEL);
+	hv_serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
+	if (!kbd_dev || !hv_serio) {
+		error = -ENOMEM;
+		goto err_free_mem;
+	}
+
+	kbd_dev->hv_dev = hv_dev;
+	kbd_dev->hv_serio = hv_serio;
+	spin_lock_init(&kbd_dev->lock);
+	init_completion(&kbd_dev->wait_event);
+	hv_set_drvdata(hv_dev, kbd_dev);
+
+	hv_serio->dev.parent  = &hv_dev->device;
+	hv_serio->id.type = SERIO_8042_XL;
+	hv_serio->port_data = kbd_dev;
+	strlcpy(hv_serio->name, dev_name(&hv_dev->device),
+		sizeof(hv_serio->name));
+	strlcpy(hv_serio->phys, dev_name(&hv_dev->device),
+		sizeof(hv_serio->phys));
+
+	hv_serio->start = hv_kbd_start;
+	hv_serio->stop = hv_kbd_stop;
+
+	error = vmbus_open(hv_dev->channel,
+			   KBD_VSC_SEND_RING_BUFFER_SIZE,
+			   KBD_VSC_RECV_RING_BUFFER_SIZE,
+			   NULL, 0,
+			   hv_kbd_on_channel_callback,
+			   hv_dev);
+	if (error)
+		goto err_free_mem;
+
+	error = hv_kbd_connect_to_vsp(hv_dev);
+	if (error)
+		goto err_close_vmbus;
+
+	serio_register_port(kbd_dev->hv_serio);
+	return 0;
+
+err_close_vmbus:
+	vmbus_close(hv_dev->channel);
+err_free_mem:
+	kfree(hv_serio);
+	kfree(kbd_dev);
+	return error;
+}
+
+static int hv_kbd_remove(struct hv_device *hv_dev)
+{
+	struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
+
+	serio_unregister_port(kbd_dev->hv_serio);
+	vmbus_close(hv_dev->channel);
+	kfree(kbd_dev);
+
+	hv_set_drvdata(hv_dev, NULL);
+
+	return 0;
+}
+
+/*
+ * Keyboard GUID
+ * {f912ad6d-2b17-48ea-bd65-f927a61c7684}
+ */
+#define HV_KBD_GUID \
+	.guid = { \
+			0x6d, 0xad, 0x12, 0xf9, 0x17, 0x2b, 0xea, 0x48, \
+			0xbd, 0x65, 0xf9, 0x27, 0xa6, 0x1c, 0x76, 0x84 \
+	}
+
+static const struct hv_vmbus_device_id id_table[] = {
+	/* Keyboard guid */
+	{ HV_KBD_GUID, },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(vmbus, id_table);
+
+static struct  hv_driver hv_kbd_drv = {
+	.name = KBUILD_MODNAME,
+	.id_table = id_table,
+	.probe = hv_kbd_probe,
+	.remove = hv_kbd_remove,
+};
+
+static int __init hv_kbd_init(void)
+{
+	return vmbus_driver_register(&hv_kbd_drv);
+}
+
+static void __exit hv_kbd_exit(void)
+{
+	vmbus_driver_unregister(&hv_kbd_drv);
+}
+
+MODULE_LICENSE("GPL");
+module_init(hv_kbd_init);
+module_exit(hv_kbd_exit);