[PATCH v11 3/5] mfd: Add driver for RAVE Supervisory Processor

[Andrey Smirnov]

Add a driver for RAVE Supervisory Processor, an MCU implementing
various bits of housekeeping functionality (watchdoging, backlight
control, LED control, etc) on RAVE family of products by Zodiac
Inflight Innovations.

This driver implementes core MFD/serdev device as well as
communication subroutines necessary for commanding the device.

Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: cphealy@xxxxxxxxx
Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
Cc: Nikita Yushchenko <nikita.yoush@xxxxxxxxxxxxxxxxxx>
Cc: Lee Jones <lee.jones@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Pavel Machek <pavel@xxxxxx>
Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Cc: Johan Hovold <johan@xxxxxxxxxx>
Cc: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxxxx>
Tested-by: Chris Healy <cphealy@xxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
---
 drivers/mfd/Kconfig         |   9 +
 drivers/mfd/Makefile        |   2 +
 drivers/mfd/rave-sp.c       | 660 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/rave-sp.h |  54 ++++
 4 files changed, 725 insertions(+)
 create mode 100644 drivers/mfd/rave-sp.c
 create mode 100644 include/linux/mfd/rave-sp.h

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index fc5e4fef89d2..8e37d4d4fad0 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1818,4 +1818,13 @@ config MFD_VEXPRESS_SYSREG
 	  on the ARM Ltd. Versatile Express board.
 
 endmenu
+
+config RAVE_SP_CORE
+	tristate "RAVE SP MCU core driver"
+	depends on SERIAL_DEV_BUS
+	select CRC_CCITT
+	help
+	  Select this to get support for the Supervisory Processor
+	  device found on several devices in RAVE line of hardware.
+
 endif
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index c3d0a1b39bb6..808ab024a796 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -226,3 +226,5 @@ obj-$(CONFIG_MFD_SUN4I_GPADC)	+= sun4i-gpadc.o
 obj-$(CONFIG_MFD_STM32_LPTIMER)	+= stm32-lptimer.o
 obj-$(CONFIG_MFD_STM32_TIMERS) 	+= stm32-timers.o
 obj-$(CONFIG_MFD_MXS_LRADC)     += mxs-lradc.o
+
+obj-$(CONFIG_RAVE_SP_CORE)	+= rave-sp.o
diff --git a/drivers/mfd/rave-sp.c b/drivers/mfd/rave-sp.c
new file mode 100644
index 000000000000..1f2912054d03
--- /dev/null
+++ b/drivers/mfd/rave-sp.c
@@ -0,0 +1,660 @@
+/*
+ * Multifunction core driver for Zodiac Inflight Innovations
+ * SP MCU that is connected via dedicated UART port
+ *
+ * Copyright (C) 2017 Zodiac Inflight Innovations
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/atomic.h>
+#include <linux/crc-ccitt.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_device.h>
+#include <linux/sched.h>
+#include <linux/serdev.h>
+#include <asm/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_SIZE		2  /* Worst case scenario on RDU2 */
+/*
+ * 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)
+
+#define RAVE_SP_BOOT_SOURCE_GET		0
+#define RAVE_SP_BOOT_SOURCE_SET		1
+
+#define RAVE_SP_RDU2_BOARD_TYPE_RMB	0
+#define RAVE_SP_RDU2_BOARD_TYPE_DEB	1
+
+#define RAVE_SP_BOOT_SOURCE_SD		0
+#define RAVE_SP_BOOT_SOURCE_EMMC	1
+#define RAVE_SP_BOOT_SOURCE_NOR		2
+
+/**
+ * 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 - 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
+ * @completion: 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:	Caculated checksum length
+ * @subroutine:	Utilized checksum algorithm implementation
+ */
+struct rave_sp_checksum {
+	size_t length;
+	void (*subroutine)(const u8 *, size_t, u8 *);
+};
+
+/**
+ * struct rave_sp_variant_cmds - Variant specific command routines
+ *
+ * @translate:	Generic to variant specific command mapping routine
+ *
+ */
+struct rave_sp_variant_cmds {
+	int (*translate)(enum rave_sp_command);
+};
+
+/**
+ * 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
+ *
+ */
+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;
+};
+
+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_ccitt_false(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(KERN_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[0]);
+	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[0] = command;
+	data[1] = 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)
+{
+	u8 cmd[] = {
+		[0] = rave_sp_reply_code(data[0]),
+		[1] = data[1],
+	};
+
+	rave_sp_write(sp, cmd, sizeof(cmd));
+
+	blocking_notifier_call_chain(&sp->event_notifier_list,
+				     rave_sp_action_pack(data[0], data[2]),
+				     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;
+	const  size_t payload_length = length - 2;
+
+	mutex_lock(&sp->reply_lock);
+	reply = sp->reply;
+
+	if (reply) {
+		if (reply->code == data[0] && reply->ackid == data[1] &&
+		    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[2], 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[0]);
+			dev_dbg(dev, "ACK ID: expected = 0x%08x received = 0x%08x\n",
+				reply->ackid, data[1]);
+			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;
+	const size_t payload_length  = length - checksum_length;
+	const u8 *crc_reported       = &data[payload_length];
+	struct device *dev           = &sp->serdev->dev;
+	u8 crc_calculated[checksum_length];
+
+	print_hex_dump(KERN_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;
+	}
+
+	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[0]))
+		rave_sp_receive_event(sp, data, length);
+	else
+		rave_sp_receive_reply(sp, data, length);
+}
+
+static int rave_sp_receive_buf(struct serdev_device *serdev,
+			       const unsigned char *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 unsigned char *src = buf;
+	const unsigned char *end = buf + size;
+	bool reset_framer = false;
+
+	while (src < end) {
+		const unsigned char byte = *src++;
+
+		switch (deframer->state) {
+		case RAVE_SP_EXPECT_SOF:
+			if (byte == RAVE_SP_STX)
+				deframer->state = RAVE_SP_EXPECT_DATA;
+			continue;
+
+		case RAVE_SP_EXPECT_DATA:
+			switch (byte) {
+			case RAVE_SP_ETX:
+				rave_sp_receive_frame(sp,
+						      deframer->data,
+						      deframer->length);
+				reset_framer = true;
+				break;
+			case RAVE_SP_STX:
+				dev_warn(dev, "Bad frame: STX before ETX\n");
+				reset_framer = true;
+				break;
+			case RAVE_SP_DLE:
+				deframer->state = RAVE_SP_EXPECT_ESCAPED_DATA;
+				continue;
+			}
+			/* FALLTHROUGH */
+
+		case RAVE_SP_EXPECT_ESCAPED_DATA:
+			deframer->data[deframer->length++] = byte;
+
+			if (deframer->length == sizeof(deframer->data)) {
+				dev_warn(dev, "Bad frame: Too long\n");
+				reset_framer = true;
+				break;
+			}
+
+			deframer->state = RAVE_SP_EXPECT_DATA;
+			break;
+		}
+	}
+
+	if (reset_framer) {
+		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_RESET:
+		return 0x1E;
+	case RAVE_SP_CMD_RESET_REASON:
+		return 0x1F;
+	default:
+		return -EINVAL;
+	}
+}
+
+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_8b2c,
+	.cmd = {
+		.translate = rave_sp_default_cmd_translate,
+	},
+};
+
+static const struct rave_sp_variant rave_sp_rdu1 = {
+	.checksum = &rave_sp_checksum_8b2c,
+	.cmd = {
+		.translate = rave_sp_rdu1_cmd_translate,
+	},
+};
+
+static const struct rave_sp_variant rave_sp_rdu2 = {
+	.checksum = &rave_sp_checksum_ccitt,
+	.cmd = {
+		.translate = rave_sp_rdu2_cmd_translate,
+	},
+};
+
+static const struct of_device_id rave_sp_dt_ids[] = {
+	{ .compatible = COMPATIBLE_RAVE_SP_NIU,  .data = &rave_sp_legacy },
+	{ .compatible = COMPATIBLE_RAVE_SP_MEZZ, .data = &rave_sp_legacy },
+	{ .compatible = COMPATIBLE_RAVE_SP_ESB,  .data = &rave_sp_legacy },
+	{ .compatible = COMPATIBLE_RAVE_SP_RDU1, .data = &rave_sp_rdu1   },
+	{ .compatible = COMPATIBLE_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;
+	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);
+
+	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@xxxxxxxxxxxxxxxxxx>");
+MODULE_AUTHOR("Nikita Yushchenko <nikita.yoush@xxxxxxxxxxxxxxxxxx>");
+MODULE_AUTHOR("Andrey Smirnov <andrew.smirnov@xxxxxxxxx>");
+MODULE_DESCRIPTION("RAVE SP core driver");
diff --git a/include/linux/mfd/rave-sp.h b/include/linux/mfd/rave-sp.h
new file mode 100644
index 000000000000..811929afc1a9
--- /dev/null
+++ b/include/linux/mfd/rave-sp.h
@@ -0,0 +1,54 @@
+#ifndef _LINUX_RAVE_SP_H_
+#define _LINUX_RAVE_SP_H_
+
+enum rave_sp_command {
+	RAVE_SP_CMD_GET_FIRMWARE_VERSION	= 0x20,
+	RAVE_SP_CMD_GET_BOOTLOADER_VERSION	= 0x21,
+	RAVE_SP_CMD_BOOT_SOURCE			= 0x26,
+	RAVE_SP_CMD_GET_BOARD_COPPER_REV	= 0x2B,
+	RAVE_SP_CMD_GET_GPIO_STATE		= 0x2F,
+
+	RAVE_SP_CMD_STATUS			= 0xA0,
+	RAVE_SP_CMD_SW_WDT			= 0xA1,
+	RAVE_SP_CMD_PET_WDT			= 0xA2,
+	RAVE_SP_CMD_RESET			= 0xA7,
+	RAVE_SP_CMD_RESET_REASON		= 0xA8,
+
+	RAVE_SP_CMD_REQ_COPPER_REV		= 0xB6,
+	RAVE_SP_CMD_GET_I2C_DEVICE_STATUS	= 0xBA,
+	RAVE_SP_CMD_GET_SP_SILICON_REV		= 0xB9,
+	RAVE_SP_CMD_CONTROL_EVENTS		= 0xBB,
+
+	RAVE_SP_EVNT_BASE			= 0xE0,
+};
+
+struct rave_sp;
+
+static inline unsigned long rave_sp_action_pack(u8 event, u8 value)
+{
+	return ((unsigned long)value << 8) | event;
+}
+
+static inline u8 rave_sp_action_unpack_event(unsigned long action)
+{
+	return action;
+}
+
+static inline u8 rave_sp_action_unpack_value(unsigned long action)
+{
+	return action >> 8;
+}
+
+int rave_sp_exec(struct rave_sp *sp,
+		 void *__data,  size_t data_size,
+		 void *reply_data, size_t reply_data_size);
+int devm_rave_sp_register_event_notifier(struct device *dev,
+					 struct notifier_block *nb);
+
+#define COMPATIBLE_RAVE_SP_NIU		"zii,rave-sp-niu"
+#define COMPATIBLE_RAVE_SP_MEZZ		"zii,rave-sp-mezz"
+#define COMPATIBLE_RAVE_SP_ESB		"zii,rave-sp-esb"
+#define COMPATIBLE_RAVE_SP_RDU1		"zii,rave-sp-rdu1"
+#define COMPATIBLE_RAVE_SP_RDU2		"zii,rave-sp-rdu2"
+
+#endif /* _LINUX_RAVE_SP_H_ */
-- 
2.13.6