Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 867 insertions, 0 deletions

diff --git a/drivers/mfd/rave-sp.c b/drivers/mfd/rave-sp.c
new file mode 100644
index 000000000..05d26d92d
--- /dev/null
+++ b/drivers/mfd/rave-sp.c
@@ -0,0 +1,867 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/*
+ * Multifunction core driver for Zodiac Inflight Innovations RAVE
+ * Supervisory Processor(SP) MCU that is connected via dedicated UART
+ * port
+ *
+ * Copyright (C) 2017 Zodiac Inflight Innovations
+ */
+
+#include <linux/atomic.h>
+#include <linux/crc-itu-t.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/mfd/rave-sp.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/sched.h>
+#include <linux/serdev.h>
+#include <linux/unaligned.h>
+
+/*
+ * UART protocol using following entities:
+ *  - message to MCU => ACK response
+ *  - event from MCU => event ACK
+ *
+ * Frame structure:
+ * <STX> <DATA> <CHECKSUM> <ETX>
+ * Where:
+ * - STX - is start of transmission character
+ * - ETX - end of transmission
+ * - DATA - payload
+ * - CHECKSUM - checksum calculated on <DATA>
+ *
+ * If <DATA> or <CHECKSUM> contain one of control characters, then it is
+ * escaped using <DLE> control code. Added <DLE> does not participate in
+ * checksum calculation.
+ */
+#define RAVE_SP_STX			0x02
+#define RAVE_SP_ETX			0x03
+#define RAVE_SP_DLE			0x10
+
+#define RAVE_SP_MAX_DATA_SIZE		64
+#define RAVE_SP_CHECKSUM_8B2C		1
+#define RAVE_SP_CHECKSUM_CCITT		2
+#define RAVE_SP_CHECKSUM_SIZE		RAVE_SP_CHECKSUM_CCITT
+/*
+ * We don't store STX, ETX and unescaped bytes, so Rx is only
+ * DATA + CSUM
+ */
+#define RAVE_SP_RX_BUFFER_SIZE				\
+	(RAVE_SP_MAX_DATA_SIZE + RAVE_SP_CHECKSUM_SIZE)
+
+#define RAVE_SP_STX_ETX_SIZE		2
+/*
+ * For Tx we have to have space for everything, STX, EXT and
+ * potentially stuffed DATA + CSUM data + csum
+ */
+#define RAVE_SP_TX_BUFFER_SIZE				\
+	(RAVE_SP_STX_ETX_SIZE + 2 * RAVE_SP_RX_BUFFER_SIZE)
+
+enum rave_sp_frame_offset {
+	RAVE_SP_FRAME_CODE_OFFSET,
+	RAVE_SP_FRAME_ACK_ID_OFFSET,
+	RAVE_SP_FRAME_DATA_OFFSET,
+};
+
+/**
+ * enum rave_sp_deframer_state - Possible state for de-framer
+ *
+ * @RAVE_SP_EXPECT_SOF:		 Scanning input for start-of-frame marker
+ * @RAVE_SP_EXPECT_DATA:	 Got start of frame marker, collecting frame
+ * @RAVE_SP_EXPECT_ESCAPED_DATA: Got escape character, collecting escaped byte
+ */
+enum rave_sp_deframer_state {
+	RAVE_SP_EXPECT_SOF,
+	RAVE_SP_EXPECT_DATA,
+	RAVE_SP_EXPECT_ESCAPED_DATA,
+};
+
+/**
+ * struct rave_sp_deframer - Device protocol deframer
+ *
+ * @state:  Current state of the deframer
+ * @data:   Buffer used to collect deframed data
+ * @length: Number of bytes de-framed so far
+ */
+struct rave_sp_deframer {
+	enum rave_sp_deframer_state state;
+	unsigned char data[RAVE_SP_RX_BUFFER_SIZE];
+	size_t length;
+};
+
+/**
+ * struct rave_sp_reply - Reply as per RAVE device protocol
+ *
+ * @length:	Expected reply length
+ * @data:	Buffer to store reply payload in
+ * @code:	Expected reply code
+ * @ackid:	Expected reply ACK ID
+ * @received:   Successful reply reception completion
+ */
+struct rave_sp_reply {
+	size_t length;
+	void  *data;
+	u8     code;
+	u8     ackid;
+	struct completion received;
+};
+
+/**
+ * struct rave_sp_checksum - Variant specific checksum implementation details
+ *
+ * @length:	Calculated checksum length
+ * @subroutine:	Utilized checksum algorithm implementation
+ */
+struct rave_sp_checksum {
+	size_t length;
+	void (*subroutine)(const u8 *, size_t, u8 *);
+};
+
+struct rave_sp_version {
+	u8     hardware;
+	__le16 major;
+	u8     minor;
+	u8     letter[2];
+} __packed;
+
+struct rave_sp_status {
+	struct rave_sp_version bootloader_version;
+	struct rave_sp_version firmware_version;
+	u16 rdu_eeprom_flag;
+	u16 dds_eeprom_flag;
+	u8  pic_flag;
+	u8  orientation;
+	u32 etc;
+	s16 temp[2];
+	u8  backlight_current[3];
+	u8  dip_switch;
+	u8  host_interrupt;
+	u16 voltage_28;
+	u8  i2c_device_status;
+	u8  power_status;
+	u8  general_status;
+	u8  deprecated1;
+	u8  power_led_status;
+	u8  deprecated2;
+	u8  periph_power_shutoff;
+} __packed;
+
+/**
+ * struct rave_sp_variant_cmds - Variant specific command routines
+ *
+ * @translate:	Generic to variant specific command mapping routine
+ * @get_status: Variant specific implementation of CMD_GET_STATUS
+ */
+struct rave_sp_variant_cmds {
+	int (*translate)(enum rave_sp_command);
+	int (*get_status)(struct rave_sp *sp, struct rave_sp_status *);
+};
+
+/**
+ * struct rave_sp_variant - RAVE supervisory processor core variant
+ *
+ * @checksum:	Variant specific checksum implementation
+ * @cmd:	Variant specific command pointer table
+ *
+ */
+struct rave_sp_variant {
+	const struct rave_sp_checksum *checksum;
+	struct rave_sp_variant_cmds cmd;
+};
+
+/**
+ * struct rave_sp - RAVE supervisory processor core
+ *
+ * @serdev:			Pointer to underlying serdev
+ * @deframer:			Stored state of the protocol deframer
+ * @ackid:			ACK ID used in last reply sent to the device
+ * @bus_lock:			Lock to serialize access to the device
+ * @reply_lock:			Lock protecting @reply
+ * @reply:			Pointer to memory to store reply payload
+ *
+ * @variant:			Device variant specific information
+ * @event_notifier_list:	Input event notification chain
+ *
+ * @part_number_firmware:	Firmware version
+ * @part_number_bootloader:	Bootloader version
+ */
+struct rave_sp {
+	struct serdev_device *serdev;
+	struct rave_sp_deframer deframer;
+	atomic_t ackid;
+	struct mutex bus_lock;
+	struct mutex reply_lock;
+	struct rave_sp_reply *reply;
+
+	const struct rave_sp_variant *variant;
+	struct blocking_notifier_head event_notifier_list;
+
+	const char *part_number_firmware;
+	const char *part_number_bootloader;
+};
+
+static bool rave_sp_id_is_event(u8 code)
+{
+	return (code & 0xF0) == RAVE_SP_EVNT_BASE;
+}
+
+static void rave_sp_unregister_event_notifier(struct device *dev, void *res)
+{
+	struct rave_sp *sp = dev_get_drvdata(dev->parent);
+	struct notifier_block *nb = *(struct notifier_block **)res;
+	struct blocking_notifier_head *bnh = &sp->event_notifier_list;
+
+	WARN_ON(blocking_notifier_chain_unregister(bnh, nb));
+}
+
+int devm_rave_sp_register_event_notifier(struct device *dev,
+					 struct notifier_block *nb)
+{
+	struct rave_sp *sp = dev_get_drvdata(dev->parent);
+	struct notifier_block **rcnb;
+	int ret;
+
+	rcnb = devres_alloc(rave_sp_unregister_event_notifier,
+			    sizeof(*rcnb), GFP_KERNEL);
+	if (!rcnb)
+		return -ENOMEM;
+
+	ret = blocking_notifier_chain_register(&sp->event_notifier_list, nb);
+	if (!ret) {
+		*rcnb = nb;
+		devres_add(dev, rcnb);
+	} else {
+		devres_free(rcnb);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devm_rave_sp_register_event_notifier);
+
+static void csum_8b2c(const u8 *buf, size_t size, u8 *crc)
+{
+	*crc = *buf++;
+	size--;
+
+	while (size--)
+		*crc += *buf++;
+
+	*crc = 1 + ~(*crc);
+}
+
+static void csum_ccitt(const u8 *buf, size_t size, u8 *crc)
+{
+	const u16 calculated = crc_itu_t(0xffff, buf, size);
+
+	/*
+	 * While the rest of the wire protocol is little-endian,
+	 * CCITT-16 CRC in RDU2 device is sent out in big-endian order.
+	 */
+	put_unaligned_be16(calculated, crc);
+}
+
+static void *stuff(unsigned char *dest, const unsigned char *src, size_t n)
+{
+	while (n--) {
+		const unsigned char byte = *src++;
+
+		switch (byte) {
+		case RAVE_SP_STX:
+		case RAVE_SP_ETX:
+		case RAVE_SP_DLE:
+			*dest++ = RAVE_SP_DLE;
+			fallthrough;
+		default:
+			*dest++ = byte;
+		}
+	}
+
+	return dest;
+}
+
+static int rave_sp_write(struct rave_sp *sp, const u8 *data, u8 data_size)
+{
+	const size_t checksum_length = sp->variant->checksum->length;
+	unsigned char frame[RAVE_SP_TX_BUFFER_SIZE];
+	unsigned char crc[RAVE_SP_CHECKSUM_SIZE];
+	unsigned char *dest = frame;
+	size_t length;
+
+	if (WARN_ON(checksum_length > sizeof(crc)))
+		return -ENOMEM;
+
+	if (WARN_ON(data_size > sizeof(frame)))
+		return -ENOMEM;
+
+	sp->variant->checksum->subroutine(data, data_size, crc);
+
+	*dest++ = RAVE_SP_STX;
+	dest = stuff(dest, data, data_size);
+	dest = stuff(dest, crc, checksum_length);
+	*dest++ = RAVE_SP_ETX;
+
+	length = dest - frame;
+
+	print_hex_dump_debug("rave-sp tx: ", DUMP_PREFIX_NONE,
+			     16, 1, frame, length, false);
+
+	return serdev_device_write(sp->serdev, frame, length, HZ);
+}
+
+static u8 rave_sp_reply_code(u8 command)
+{
+	/*
+	 * There isn't a single rule that describes command code ->
+	 * ACK code transformation, but, going through various
+	 * versions of ICDs, there appear to be three distinct groups
+	 * that can be described by simple transformation.
+	 */
+	switch (command) {
+	case 0xA0 ... 0xBE:
+		/*
+		 * Commands implemented by firmware found in RDU1 and
+		 * older devices all seem to obey the following rule
+		 */
+		return command + 0x20;
+	case 0xE0 ... 0xEF:
+		/*
+		 * Events emitted by all versions of the firmare use
+		 * least significant bit to get an ACK code
+		 */
+		return command | 0x01;
+	default:
+		/*
+		 * Commands implemented by firmware found in RDU2 are
+		 * similar to "old" commands, but they use slightly
+		 * different offset
+		 */
+		return command + 0x40;
+	}
+}
+
+int rave_sp_exec(struct rave_sp *sp,
+		 void *__data,  size_t data_size,
+		 void *reply_data, size_t reply_data_size)
+{
+	struct rave_sp_reply reply = {
+		.data     = reply_data,
+		.length   = reply_data_size,
+		.received = COMPLETION_INITIALIZER_ONSTACK(reply.received),
+	};
+	unsigned char *data = __data;
+	int command, ret = 0;
+	u8 ackid;
+
+	command = sp->variant->cmd.translate(data[RAVE_SP_FRAME_CODE_OFFSET]);
+	if (command < 0)
+		return command;
+
+	ackid       = atomic_inc_return(&sp->ackid);
+	reply.ackid = ackid;
+	reply.code  = rave_sp_reply_code((u8)command);
+
+	mutex_lock(&sp->bus_lock);
+
+	mutex_lock(&sp->reply_lock);
+	sp->reply = &reply;
+	mutex_unlock(&sp->reply_lock);
+
+	data[RAVE_SP_FRAME_CODE_OFFSET] = command;
+	data[RAVE_SP_FRAME_ACK_ID_OFFSET] = ackid;
+
+	rave_sp_write(sp, data, data_size);
+
+	if (!wait_for_completion_timeout(&reply.received, HZ)) {
+		dev_err(&sp->serdev->dev, "Command timeout\n");
+		ret = -ETIMEDOUT;
+
+		mutex_lock(&sp->reply_lock);
+		sp->reply = NULL;
+		mutex_unlock(&sp->reply_lock);
+	}
+
+	mutex_unlock(&sp->bus_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rave_sp_exec);
+
+static void rave_sp_receive_event(struct rave_sp *sp,
+				  const unsigned char *data, size_t length)
+{
+	unsigned long action;
+	u8 cmd[RAVE_SP_FRAME_DATA_OFFSET];
+
+	if (length < RAVE_SP_FRAME_DATA_OFFSET + 1) {
+		dev_warn(&sp->serdev->dev, "Dropping short event frame\n");
+		return;
+	}
+
+	cmd[RAVE_SP_FRAME_CODE_OFFSET] =
+		rave_sp_reply_code(data[RAVE_SP_FRAME_CODE_OFFSET]);
+	cmd[RAVE_SP_FRAME_ACK_ID_OFFSET] = data[RAVE_SP_FRAME_ACK_ID_OFFSET];
+
+	rave_sp_write(sp, cmd, sizeof(cmd));
+
+	action = rave_sp_action_pack(data[RAVE_SP_FRAME_CODE_OFFSET],
+				     data[RAVE_SP_FRAME_DATA_OFFSET]);
+	blocking_notifier_call_chain(&sp->event_notifier_list, action, NULL);
+}
+
+static void rave_sp_receive_reply(struct rave_sp *sp,
+				  const unsigned char *data, size_t length)
+{
+	struct device *dev = &sp->serdev->dev;
+	struct rave_sp_reply *reply;
+	size_t payload_length;
+
+	if (length < RAVE_SP_FRAME_DATA_OFFSET) {
+		dev_warn(dev, "Dropping short reply frame\n");
+		return;
+	}
+	payload_length = length - RAVE_SP_FRAME_DATA_OFFSET;
+
+	mutex_lock(&sp->reply_lock);
+	reply = sp->reply;
+
+	if (reply) {
+		if (reply->code == data[RAVE_SP_FRAME_CODE_OFFSET] &&
+		    reply->ackid == data[RAVE_SP_FRAME_ACK_ID_OFFSET] &&
+		    payload_length >= reply->length) {
+			/*
+			 * We are relying on memcpy(dst, src, 0) to be a no-op
+			 * when handling commands that have a no-payload reply
+			 */
+			memcpy(reply->data, &data[RAVE_SP_FRAME_DATA_OFFSET],
+			       reply->length);
+			complete(&reply->received);
+			sp->reply = NULL;
+		} else {
+			dev_err(dev, "Ignoring incorrect reply\n");
+			dev_dbg(dev, "Code:   expected = 0x%08x received = 0x%08x\n",
+				reply->code, data[RAVE_SP_FRAME_CODE_OFFSET]);
+			dev_dbg(dev, "ACK ID: expected = 0x%08x received = 0x%08x\n",
+				reply->ackid, data[RAVE_SP_FRAME_ACK_ID_OFFSET]);
+			dev_dbg(dev, "Length: expected = %zu received = %zu\n",
+				reply->length, payload_length);
+		}
+	}
+
+	mutex_unlock(&sp->reply_lock);
+}
+
+static void rave_sp_receive_frame(struct rave_sp *sp,
+				  const unsigned char *data,
+				  size_t length)
+{
+	const size_t checksum_length = sp->variant->checksum->length;
+	struct device *dev           = &sp->serdev->dev;
+	u8 crc_calculated[RAVE_SP_CHECKSUM_SIZE];
+	const u8 *crc_reported;
+	size_t payload_length;
+
+	if (unlikely(checksum_length > sizeof(crc_calculated))) {
+		dev_warn(dev, "Checksum too long, dropping\n");
+		return;
+	}
+
+	print_hex_dump_debug("rave-sp rx: ", DUMP_PREFIX_NONE,
+			     16, 1, data, length, false);
+
+	if (unlikely(length <= checksum_length)) {
+		dev_warn(dev, "Dropping short frame\n");
+		return;
+	}
+
+	payload_length = length - checksum_length;
+	crc_reported = &data[payload_length];
+
+	sp->variant->checksum->subroutine(data, payload_length,
+					  crc_calculated);
+
+	if (memcmp(crc_calculated, crc_reported, checksum_length)) {
+		dev_warn(dev, "Dropping bad frame\n");
+		return;
+	}
+
+	if (rave_sp_id_is_event(data[RAVE_SP_FRAME_CODE_OFFSET]))
+		rave_sp_receive_event(sp, data, payload_length);
+	else
+		rave_sp_receive_reply(sp, data, payload_length);
+}
+
+static size_t rave_sp_receive_buf(struct serdev_device *serdev,
+				  const u8 *buf, size_t size)
+{
+	struct device *dev = &serdev->dev;
+	struct rave_sp *sp = dev_get_drvdata(dev);
+	struct rave_sp_deframer *deframer = &sp->deframer;
+	const u8 *src = buf;
+	const u8 *end = buf + size;
+
+	while (src < end) {
+		const u8 byte = *src++;
+
+		switch (deframer->state) {
+		case RAVE_SP_EXPECT_SOF:
+			if (byte == RAVE_SP_STX)
+				deframer->state = RAVE_SP_EXPECT_DATA;
+			break;
+
+		case RAVE_SP_EXPECT_DATA:
+			/*
+			 * Treat special byte values first
+			 */
+			switch (byte) {
+			case RAVE_SP_ETX:
+				rave_sp_receive_frame(sp,
+						      deframer->data,
+						      deframer->length);
+				/*
+				 * Once we extracted a complete frame
+				 * out of a stream, we call it done
+				 * and proceed to bailing out while
+				 * resetting the framer to initial
+				 * state, regardless if we've consumed
+				 * all of the stream or not.
+				 */
+				goto reset_framer;
+			case RAVE_SP_STX:
+				dev_warn(dev, "Bad frame: STX before ETX\n");
+				/*
+				 * If we encounter second "start of
+				 * the frame" marker before seeing
+				 * corresponding "end of frame", we
+				 * reset the framer and ignore both:
+				 * frame started by first SOF and
+				 * frame started by current SOF.
+				 *
+				 * NOTE: The above means that only the
+				 * frame started by third SOF, sent
+				 * after this one will have a chance
+				 * to get throught.
+				 */
+				goto reset_framer;
+			case RAVE_SP_DLE:
+				deframer->state = RAVE_SP_EXPECT_ESCAPED_DATA;
+				/*
+				 * If we encounter escape sequence we
+				 * need to skip it and collect the
+				 * byte that follows. We do it by
+				 * forcing the next iteration of the
+				 * encompassing while loop.
+				 */
+				continue;
+			}
+			/*
+			 * For the rest of the bytes, that are not
+			 * speical snoflakes, we do the same thing
+			 * that we do to escaped data - collect it in
+			 * deframer buffer
+			 */
+
+			fallthrough;
+
+		case RAVE_SP_EXPECT_ESCAPED_DATA:
+			if (deframer->length == sizeof(deframer->data)) {
+				dev_warn(dev, "Bad frame: Too long\n");
+				/*
+				 * If the amount of data we've
+				 * accumulated for current frame so
+				 * far starts to exceed the capacity
+				 * of deframer's buffer, there's
+				 * nothing else we can do but to
+				 * discard that data and start
+				 * assemblying a new frame again
+				 */
+				goto reset_framer;
+			}
+
+			deframer->data[deframer->length++] = byte;
+
+			/*
+			 * We've extracted out special byte, now we
+			 * can go back to regular data collecting
+			 */
+			deframer->state = RAVE_SP_EXPECT_DATA;
+			break;
+		}
+	}
+
+	/*
+	 * The only way to get out of the above loop and end up here
+	 * is throught consuming all of the supplied data, so here we
+	 * report that we processed it all.
+	 */
+	return size;
+
+reset_framer:
+	/*
+	 * NOTE: A number of codepaths that will drop us here will do
+	 * so before consuming all 'size' bytes of the data passed by
+	 * serdev layer. We rely on the fact that serdev layer will
+	 * re-execute this handler with the remainder of the Rx bytes
+	 * once we report actual number of bytes that we processed.
+	 */
+	deframer->state  = RAVE_SP_EXPECT_SOF;
+	deframer->length = 0;
+
+	return src - buf;
+}
+
+static int rave_sp_rdu1_cmd_translate(enum rave_sp_command command)
+{
+	if (command >= RAVE_SP_CMD_STATUS &&
+	    command <= RAVE_SP_CMD_CONTROL_EVENTS)
+		return command;
+
+	return -EINVAL;
+}
+
+static int rave_sp_rdu2_cmd_translate(enum rave_sp_command command)
+{
+	if (command >= RAVE_SP_CMD_GET_FIRMWARE_VERSION &&
+	    command <= RAVE_SP_CMD_GET_GPIO_STATE)
+		return command;
+
+	if (command == RAVE_SP_CMD_REQ_COPPER_REV) {
+		/*
+		 * As per RDU2 ICD 3.4.47 CMD_GET_COPPER_REV code is
+		 * different from that for RDU1 and it is set to 0x28.
+		 */
+		return 0x28;
+	}
+
+	return rave_sp_rdu1_cmd_translate(command);
+}
+
+static int rave_sp_default_cmd_translate(enum rave_sp_command command)
+{
+	/*
+	 * All of the following command codes were taken from "Table :
+	 * Communications Protocol Message Types" in section 3.3
+	 * "MESSAGE TYPES" of Rave PIC24 ICD.
+	 */
+	switch (command) {
+	case RAVE_SP_CMD_GET_FIRMWARE_VERSION:
+		return 0x11;
+	case RAVE_SP_CMD_GET_BOOTLOADER_VERSION:
+		return 0x12;
+	case RAVE_SP_CMD_BOOT_SOURCE:
+		return 0x14;
+	case RAVE_SP_CMD_SW_WDT:
+		return 0x1C;
+	case RAVE_SP_CMD_PET_WDT:
+		return 0x1D;
+	case RAVE_SP_CMD_RESET:
+		return 0x1E;
+	case RAVE_SP_CMD_RESET_REASON:
+		return 0x1F;
+	case RAVE_SP_CMD_RMB_EEPROM:
+		return 0x20;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const char *devm_rave_sp_version(struct device *dev,
+					struct rave_sp_version *version)
+{
+	/*
+	 * NOTE: The format string below uses %02d to display u16
+	 * intentionally for the sake of backwards compatibility with
+	 * legacy software.
+	 */
+	return devm_kasprintf(dev, GFP_KERNEL, "%02d%02d%02d.%c%c\n",
+			      version->hardware,
+			      le16_to_cpu(version->major),
+			      version->minor,
+			      version->letter[0],
+			      version->letter[1]);
+}
+
+static int rave_sp_rdu1_get_status(struct rave_sp *sp,
+				   struct rave_sp_status *status)
+{
+	u8 cmd[] = {
+		[0] = RAVE_SP_CMD_STATUS,
+		[1] = 0
+	};
+
+	return rave_sp_exec(sp, cmd, sizeof(cmd), status, sizeof(*status));
+}
+
+static int rave_sp_emulated_get_status(struct rave_sp *sp,
+				       struct rave_sp_status *status)
+{
+	u8 cmd[] = {
+		[0] = RAVE_SP_CMD_GET_FIRMWARE_VERSION,
+		[1] = 0,
+	};
+	int ret;
+
+	ret = rave_sp_exec(sp, cmd, sizeof(cmd), &status->firmware_version,
+			   sizeof(status->firmware_version));
+	if (ret)
+		return ret;
+
+	cmd[0] = RAVE_SP_CMD_GET_BOOTLOADER_VERSION;
+	return rave_sp_exec(sp, cmd, sizeof(cmd), &status->bootloader_version,
+			    sizeof(status->bootloader_version));
+}
+
+static int rave_sp_get_status(struct rave_sp *sp)
+{
+	struct device *dev = &sp->serdev->dev;
+	struct rave_sp_status status;
+	const char *version;
+	int ret;
+
+	ret = sp->variant->cmd.get_status(sp, &status);
+	if (ret)
+		return ret;
+
+	version = devm_rave_sp_version(dev, &status.firmware_version);
+	if (!version)
+		return -ENOMEM;
+
+	sp->part_number_firmware = version;
+
+	version = devm_rave_sp_version(dev, &status.bootloader_version);
+	if (!version)
+		return -ENOMEM;
+
+	sp->part_number_bootloader = version;
+
+	return 0;
+}
+
+static const struct rave_sp_checksum rave_sp_checksum_8b2c = {
+	.length     = 1,
+	.subroutine = csum_8b2c,
+};
+
+static const struct rave_sp_checksum rave_sp_checksum_ccitt = {
+	.length     = 2,
+	.subroutine = csum_ccitt,
+};
+
+static const struct rave_sp_variant rave_sp_legacy = {
+	.checksum = &rave_sp_checksum_ccitt,
+	.cmd = {
+		.translate = rave_sp_default_cmd_translate,
+		.get_status = rave_sp_emulated_get_status,
+	},
+};
+
+static const struct rave_sp_variant rave_sp_rdu1 = {
+	.checksum = &rave_sp_checksum_8b2c,
+	.cmd = {
+		.translate = rave_sp_rdu1_cmd_translate,
+		.get_status = rave_sp_rdu1_get_status,
+	},
+};
+
+static const struct rave_sp_variant rave_sp_rdu2 = {
+	.checksum = &rave_sp_checksum_ccitt,
+	.cmd = {
+		.translate = rave_sp_rdu2_cmd_translate,
+		.get_status = rave_sp_emulated_get_status,
+	},
+};
+
+static const struct of_device_id rave_sp_dt_ids[] = {
+	{ .compatible = "zii,rave-sp-niu",  .data = &rave_sp_legacy },
+	{ .compatible = "zii,rave-sp-mezz", .data = &rave_sp_legacy },
+	{ .compatible = "zii,rave-sp-esb",  .data = &rave_sp_legacy },
+	{ .compatible = "zii,rave-sp-rdu1", .data = &rave_sp_rdu1   },
+	{ .compatible = "zii,rave-sp-rdu2", .data = &rave_sp_rdu2   },
+	{ /* sentinel */ }
+};
+
+static const struct serdev_device_ops rave_sp_serdev_device_ops = {
+	.receive_buf  = rave_sp_receive_buf,
+	.write_wakeup = serdev_device_write_wakeup,
+};
+
+static int rave_sp_probe(struct serdev_device *serdev)
+{
+	struct device *dev = &serdev->dev;
+	const char *unknown = "unknown\n";
+	struct rave_sp *sp;
+	u32 baud;
+	int ret;
+
+	if (of_property_read_u32(dev->of_node, "current-speed", &baud)) {
+		dev_err(dev,
+			"'current-speed' is not specified in device node\n");
+		return -EINVAL;
+	}
+
+	sp = devm_kzalloc(dev, sizeof(*sp), GFP_KERNEL);
+	if (!sp)
+		return -ENOMEM;
+
+	sp->serdev = serdev;
+	dev_set_drvdata(dev, sp);
+
+	sp->variant = of_device_get_match_data(dev);
+	if (!sp->variant)
+		return -ENODEV;
+
+	mutex_init(&sp->bus_lock);
+	mutex_init(&sp->reply_lock);
+	BLOCKING_INIT_NOTIFIER_HEAD(&sp->event_notifier_list);
+
+	serdev_device_set_client_ops(serdev, &rave_sp_serdev_device_ops);
+	ret = devm_serdev_device_open(dev, serdev);
+	if (ret)
+		return ret;
+
+	serdev_device_set_baudrate(serdev, baud);
+	serdev_device_set_flow_control(serdev, false);
+
+	ret = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE);
+	if (ret) {
+		dev_err(dev, "Failed to set parity\n");
+		return ret;
+	}
+
+	ret = rave_sp_get_status(sp);
+	if (ret) {
+		dev_warn(dev, "Failed to get firmware status: %d\n", ret);
+		sp->part_number_firmware   = unknown;
+		sp->part_number_bootloader = unknown;
+	}
+
+	/*
+	 * Those strings already have a \n embedded, so there's no
+	 * need to have one in format string.
+	 */
+	dev_info(dev, "Firmware version: %s",   sp->part_number_firmware);
+	dev_info(dev, "Bootloader version: %s", sp->part_number_bootloader);
+
+	return devm_of_platform_populate(dev);
+}
+
+MODULE_DEVICE_TABLE(of, rave_sp_dt_ids);
+
+static struct serdev_device_driver rave_sp_drv = {
+	.probe			= rave_sp_probe,
+	.driver = {
+		.name		= "rave-sp",
+		.of_match_table	= rave_sp_dt_ids,
+	},
+};
+module_serdev_device_driver(rave_sp_drv);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Andrey Vostrikov <andrey.vostrikov@cogentembedded.com>");
+MODULE_AUTHOR("Nikita Yushchenko <nikita.yoush@cogentembedded.com>");
+MODULE_AUTHOR("Andrey Smirnov <andrew.smirnov@gmail.com>");
+MODULE_DESCRIPTION("RAVE SP core driver");