drivers/spi/spi-fsi.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 // Copyright (C) IBM Corporation 2020

 #include <linux/bitfield.h>
 #include <linux/bits.h>
 #include <linux/fsi.h>
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/spi/spi.h>

 #define FSI_ENGID_SPI			0x23
 #define FSI_MBOX_ROOT_CTRL_8		0x2860
 #define  FSI_MBOX_ROOT_CTRL_8_SPI_MUX	 0xf0000000

 #define FSI2SPI_DATA0			0x00
 #define FSI2SPI_DATA1			0x04
 #define FSI2SPI_CMD			0x08
 #define  FSI2SPI_CMD_WRITE		 BIT(31)
 #define FSI2SPI_RESET			0x18
 #define FSI2SPI_STATUS			0x1c
 #define  FSI2SPI_STATUS_ANY_ERROR	 BIT(31)
 #define FSI2SPI_IRQ			0x20

 #define SPI_FSI_BASE			0x70000
 #define SPI_FSI_TIMEOUT_MS		1000
 #define SPI_FSI_MAX_RX_SIZE		8
 #define SPI_FSI_MAX_TX_SIZE		40

 #define SPI_FSI_ERROR			0x0
 #define SPI_FSI_COUNTER_CFG		0x1
 #define SPI_FSI_CFG1			0x2
 #define SPI_FSI_CLOCK_CFG		0x3
 #define  SPI_FSI_CLOCK_CFG_MM_ENABLE	 BIT_ULL(32)
 #define  SPI_FSI_CLOCK_CFG_ECC_DISABLE	 (BIT_ULL(35) | BIT_ULL(33))
 #define  SPI_FSI_CLOCK_CFG_RESET1	 (BIT_ULL(36) | BIT_ULL(38))
 #define  SPI_FSI_CLOCK_CFG_RESET2	 (BIT_ULL(37) | BIT_ULL(39))
 #define  SPI_FSI_CLOCK_CFG_MODE		 (BIT_ULL(41) | BIT_ULL(42))
 #define  SPI_FSI_CLOCK_CFG_SCK_RECV_DEL	 GENMASK_ULL(51, 44)
 #define   SPI_FSI_CLOCK_CFG_SCK_NO_DEL	  BIT_ULL(51)
 #define  SPI_FSI_CLOCK_CFG_SCK_DIV	 GENMASK_ULL(63, 52)
 #define SPI_FSI_MMAP			0x4
 #define SPI_FSI_DATA_TX			0x5
 #define SPI_FSI_DATA_RX			0x6
 #define SPI_FSI_SEQUENCE		0x7
 #define  SPI_FSI_SEQUENCE_STOP		 0x00
 #define  SPI_FSI_SEQUENCE_SEL_SLAVE(x)	 (0x10 | ((x) & 0xf))
 #define  SPI_FSI_SEQUENCE_SHIFT_OUT(x)	 (0x30 | ((x) & 0xf))
 #define  SPI_FSI_SEQUENCE_SHIFT_IN(x)	 (0x40 | ((x) & 0xf))
 #define  SPI_FSI_SEQUENCE_COPY_DATA_TX	 0xc0
 #define  SPI_FSI_SEQUENCE_BRANCH(x)	 (0xe0 | ((x) & 0xf))
 #define SPI_FSI_STATUS			0x8
 #define  SPI_FSI_STATUS_ERROR		 \
 	(GENMASK_ULL(31, 21) | GENMASK_ULL(15, 12))
 #define  SPI_FSI_STATUS_SEQ_STATE	 GENMASK_ULL(55, 48)
 #define   SPI_FSI_STATUS_SEQ_STATE_IDLE	  BIT_ULL(48)
 #define  SPI_FSI_STATUS_TDR_UNDERRUN	 BIT_ULL(57)
 #define  SPI_FSI_STATUS_TDR_OVERRUN	 BIT_ULL(58)
 #define  SPI_FSI_STATUS_TDR_FULL	 BIT_ULL(59)
 #define  SPI_FSI_STATUS_RDR_UNDERRUN	 BIT_ULL(61)
 #define  SPI_FSI_STATUS_RDR_OVERRUN	 BIT_ULL(62)
 #define  SPI_FSI_STATUS_RDR_FULL	 BIT_ULL(63)
 #define  SPI_FSI_STATUS_ANY_ERROR	 \
 	(SPI_FSI_STATUS_ERROR | \
 	 SPI_FSI_STATUS_TDR_OVERRUN | SPI_FSI_STATUS_RDR_UNDERRUN | \
 	 SPI_FSI_STATUS_RDR_OVERRUN)
 #define SPI_FSI_PORT_CTRL		0x9

 struct fsi2spi {
 	struct fsi_device *fsi; /* FSI2SPI CFAM engine device */
 	struct mutex lock; /* lock access to the device */
 };

 struct fsi_spi {
 	struct device *dev;	/* SPI controller device */
 	struct fsi2spi *bridge; /* FSI2SPI device */
 	u32 base;
 };

 struct fsi_spi_sequence {
 	int bit;
 	u64 data;
 };

 static int fsi_spi_check_mux(struct fsi_device *fsi, struct device *dev)
 {
 	int rc;
 	u32 root_ctrl_8;
 	__be32 root_ctrl_8_be;

 	rc = fsi_slave_read(fsi->slave, FSI_MBOX_ROOT_CTRL_8, &root_ctrl_8_be,
 			    sizeof(root_ctrl_8_be));
 	if (rc)
 		return rc;

 	root_ctrl_8 = be32_to_cpu(root_ctrl_8_be);
 	dev_dbg(dev, "Root control register 8: %08x\n", root_ctrl_8);
 	if ((root_ctrl_8 & FSI_MBOX_ROOT_CTRL_8_SPI_MUX) ==
 	     FSI_MBOX_ROOT_CTRL_8_SPI_MUX)
 		return 0;

 	return -ENOLINK;
 }

 static int fsi_spi_check_status(struct fsi_spi *ctx)
 {
 	int rc;
 	u32 sts;
 	__be32 sts_be;

 	rc = fsi_device_read(ctx->bridge->fsi, FSI2SPI_STATUS, &sts_be,
 			     sizeof(sts_be));
 	if (rc)
 		return rc;

 	sts = be32_to_cpu(sts_be);
 	if (sts & FSI2SPI_STATUS_ANY_ERROR) {
 		dev_err(ctx->dev, "Error with FSI2SPI interface: %08x.\n", sts);
 		return -EIO;
 	}

 	return 0;
 }

 static int fsi_spi_read_reg(struct fsi_spi *ctx, u32 offset, u64 *value)
 {
 	int rc = 0;
 	__be32 cmd_be;
 	__be32 data_be;
 	u32 cmd = offset + ctx->base;
 	struct fsi2spi *bridge = ctx->bridge;

 	*value = 0ULL;

 	if (cmd & FSI2SPI_CMD_WRITE)
 		return -EINVAL;

 	rc = mutex_lock_interruptible(&bridge->lock);
 	if (rc)
 		return rc;

 	cmd_be = cpu_to_be32(cmd);
 	rc = fsi_device_write(bridge->fsi, FSI2SPI_CMD, &cmd_be,
 			      sizeof(cmd_be));
 	if (rc)
 		goto unlock;

 	rc = fsi_spi_check_status(ctx);
 	if (rc)
 		goto unlock;

 	rc = fsi_device_read(bridge->fsi, FSI2SPI_DATA0, &data_be,
 			     sizeof(data_be));
 	if (rc)
 		goto unlock;

 	*value |= (u64)be32_to_cpu(data_be) << 32;

 	rc = fsi_device_read(bridge->fsi, FSI2SPI_DATA1, &data_be,
 			     sizeof(data_be));
 	if (rc)
 		goto unlock;

 	*value |= (u64)be32_to_cpu(data_be);
 	dev_dbg(ctx->dev, "Read %02x[%016llx].\n", offset, *value);

 unlock:
 	mutex_unlock(&bridge->lock);
 	return rc;
 }

 static int fsi_spi_write_reg(struct fsi_spi *ctx, u32 offset, u64 value)
 {
 	int rc = 0;
 	__be32 cmd_be;
 	__be32 data_be;
 	u32 cmd = offset + ctx->base;
 	struct fsi2spi *bridge = ctx->bridge;

 	if (cmd & FSI2SPI_CMD_WRITE)
 		return -EINVAL;

 	rc = mutex_lock_interruptible(&bridge->lock);
 	if (rc)
 		return rc;

 	dev_dbg(ctx->dev, "Write %02x[%016llx].\n", offset, value);

 	data_be = cpu_to_be32(upper_32_bits(value));
 	rc = fsi_device_write(bridge->fsi, FSI2SPI_DATA0, &data_be,
 			      sizeof(data_be));
 	if (rc)
 		goto unlock;

 	data_be = cpu_to_be32(lower_32_bits(value));
 	rc = fsi_device_write(bridge->fsi, FSI2SPI_DATA1, &data_be,
 			      sizeof(data_be));
 	if (rc)
 		goto unlock;

 	cmd_be = cpu_to_be32(cmd | FSI2SPI_CMD_WRITE);
 	rc = fsi_device_write(bridge->fsi, FSI2SPI_CMD, &cmd_be,
 			      sizeof(cmd_be));
 	if (rc)
 		goto unlock;

 	rc = fsi_spi_check_status(ctx);

 unlock:
 	mutex_unlock(&bridge->lock);
 	return rc;
 }

 static int fsi_spi_data_in(u64 in, u8 *rx, int len)
 {
 	int i;
 	int num_bytes = min(len, 8);

 	for (i = 0; i < num_bytes; ++i)
 		rx[i] = (u8)(in >> (8 * ((num_bytes - 1) - i)));

 	return num_bytes;
 }

 static int fsi_spi_data_out(u64 *out, const u8 *tx, int len)
 {
 	int i;
 	int num_bytes = min(len, 8);
 	u8 *out_bytes = (u8 *)out;

 	/* Unused bytes of the tx data should be 0. */
 	*out = 0ULL;

 	for (i = 0; i < num_bytes; ++i)
 		out_bytes[8 - (i + 1)] = tx[i];

 	return num_bytes;
 }

 static int fsi_spi_reset(struct fsi_spi *ctx)
 {
 	int rc;

 	dev_dbg(ctx->dev, "Resetting SPI controller.\n");

 	rc = fsi_spi_write_reg(ctx, SPI_FSI_CLOCK_CFG,
 			       SPI_FSI_CLOCK_CFG_RESET1);
 	if (rc)
 		return rc;

 	rc = fsi_spi_write_reg(ctx, SPI_FSI_CLOCK_CFG,
 			       SPI_FSI_CLOCK_CFG_RESET2);
 	if (rc)
 		return rc;

 	return fsi_spi_write_reg(ctx, SPI_FSI_STATUS, 0ULL);
 }

 static int fsi_spi_status(struct fsi_spi *ctx, u64 *status, const char *dir)
 {
 	int rc = fsi_spi_read_reg(ctx, SPI_FSI_STATUS, status);

 	if (rc)
 		return rc;

 	if (*status & SPI_FSI_STATUS_ANY_ERROR) {
 		dev_err(ctx->dev, "%s error: %016llx\n", dir, *status);

 		rc = fsi_spi_reset(ctx);
 		if (rc)
 			return rc;

 		return -EREMOTEIO;
 	}

 	return 0;
 }

 static void fsi_spi_sequence_add(struct fsi_spi_sequence *seq, u8 val)
 {
 	/*
 	 * Add the next byte of instruction to the 8-byte sequence register.
 	 * Then decrement the counter so that the next instruction will go in
 	 * the right place. Return the index of the slot we just filled in the
 	 * sequence register.
 	 */
 	seq->data |= (u64)val << seq->bit;
 	seq->bit -= 8;
 }

 static void fsi_spi_sequence_init(struct fsi_spi_sequence *seq)
 {
 	seq->bit = 56;
 	seq->data = 0ULL;
 }

 static int fsi_spi_transfer_data(struct fsi_spi *ctx,
 				 struct spi_transfer *transfer)
 {
 	int loops;
 	int rc = 0;
 	unsigned long end;
 	u64 status = 0ULL;

 	if (transfer->tx_buf) {
 		int nb;
 		int sent = 0;
 		u64 out = 0ULL;
 		const u8 *tx = transfer->tx_buf;

 		while (transfer->len > sent) {
 			nb = fsi_spi_data_out(&out, &tx[sent],
 					      (int)transfer->len - sent);

 			rc = fsi_spi_write_reg(ctx, SPI_FSI_DATA_TX, out);
 			if (rc)
 				return rc;

 			loops = 0;
 			end = jiffies + msecs_to_jiffies(SPI_FSI_TIMEOUT_MS);
 			do {
 				if (loops++ && time_after(jiffies, end))
 					return -ETIMEDOUT;

 				rc = fsi_spi_status(ctx, &status, "TX");
 				if (rc)
 					return rc;
 			} while (status & SPI_FSI_STATUS_TDR_FULL);

 			sent += nb;
 		}
 	} else if (transfer->rx_buf) {
 		int recv = 0;
 		u64 in = 0ULL;
 		u8 *rx = transfer->rx_buf;

 		while (transfer->len > recv) {
 			loops = 0;
 			end = jiffies + msecs_to_jiffies(SPI_FSI_TIMEOUT_MS);
 			do {
 				if (loops++ && time_after(jiffies, end))
 					return -ETIMEDOUT;

 				rc = fsi_spi_status(ctx, &status, "RX");
 				if (rc)
 					return rc;
 			} while (!(status & SPI_FSI_STATUS_RDR_FULL));

 			rc = fsi_spi_read_reg(ctx, SPI_FSI_DATA_RX, &in);
 			if (rc)
 				return rc;

 			recv += fsi_spi_data_in(in, &rx[recv],
 						(int)transfer->len - recv);
 		}
 	}

 	return 0;
 }

 static int fsi_spi_transfer_init(struct fsi_spi *ctx)
 {
 	int loops = 0;
 	int rc;
 	bool reset = false;
 	unsigned long end;
 	u64 seq_state;
 	u64 clock_cfg = 0ULL;
 	u64 status = 0ULL;
 	u64 wanted_clock_cfg = SPI_FSI_CLOCK_CFG_ECC_DISABLE |
 		SPI_FSI_CLOCK_CFG_SCK_NO_DEL |
 		FIELD_PREP(SPI_FSI_CLOCK_CFG_SCK_DIV, 19);

 	end = jiffies + msecs_to_jiffies(SPI_FSI_TIMEOUT_MS);
 	do {
 		if (loops++ && time_after(jiffies, end))
 			return -ETIMEDOUT;

 		rc = fsi_spi_read_reg(ctx, SPI_FSI_STATUS, &status);
 		if (rc)
 			return rc;

 		seq_state = status & SPI_FSI_STATUS_SEQ_STATE;

 		if (status & (SPI_FSI_STATUS_ANY_ERROR |
 			      SPI_FSI_STATUS_TDR_FULL |
 			      SPI_FSI_STATUS_RDR_FULL)) {
 			if (reset) {
 				dev_err(ctx->dev,
 					"Initialization error: %08llx\n",
 					status);
 				return -EIO;
 			}

 			rc = fsi_spi_reset(ctx);
 			if (rc)
 				return rc;

 			reset = true;
 			continue;
 		}
 	} while (seq_state && (seq_state != SPI_FSI_STATUS_SEQ_STATE_IDLE));

 	rc = fsi_spi_write_reg(ctx, SPI_FSI_COUNTER_CFG, 0ULL);
 	if (rc)
 		return rc;

 	rc = fsi_spi_read_reg(ctx, SPI_FSI_CLOCK_CFG, &clock_cfg);
 	if (rc)
 		return rc;

 	if ((clock_cfg & (SPI_FSI_CLOCK_CFG_MM_ENABLE |
 			  SPI_FSI_CLOCK_CFG_ECC_DISABLE |
 			  SPI_FSI_CLOCK_CFG_MODE |
 			  SPI_FSI_CLOCK_CFG_SCK_RECV_DEL |
 			  SPI_FSI_CLOCK_CFG_SCK_DIV)) != wanted_clock_cfg)
 		rc = fsi_spi_write_reg(ctx, SPI_FSI_CLOCK_CFG,
 				       wanted_clock_cfg);

 	return rc;
 }

 static int fsi_spi_transfer_one_message(struct spi_controller *ctlr,
 					struct spi_message *mesg)
 {
 	int rc;
 	u8 seq_slave = SPI_FSI_SEQUENCE_SEL_SLAVE(spi_get_chipselect(mesg->spi, 0) + 1);
 	unsigned int len;
 	struct spi_transfer *transfer;
 	struct fsi_spi *ctx = spi_controller_get_devdata(ctlr);

 	rc = fsi_spi_check_mux(ctx->bridge->fsi, ctx->dev);
 	if (rc)
 		goto error;

 	list_for_each_entry(transfer, &mesg->transfers, transfer_list) {
 		struct fsi_spi_sequence seq;
 		struct spi_transfer *next = NULL;

 		/* Sequencer must do shift out (tx) first. */
 		if (!transfer->tx_buf || transfer->len > SPI_FSI_MAX_TX_SIZE) {
 			rc = -EINVAL;
 			goto error;
 		}

 		dev_dbg(ctx->dev, "Start tx of %d bytes.\n", transfer->len);

 		rc = fsi_spi_transfer_init(ctx);
 		if (rc < 0)
 			goto error;

 		fsi_spi_sequence_init(&seq);
 		fsi_spi_sequence_add(&seq, seq_slave);

 		len = transfer->len;
 		while (len > 8) {
 			fsi_spi_sequence_add(&seq,
 					     SPI_FSI_SEQUENCE_SHIFT_OUT(8));
 			len -= 8;
 		}
 		fsi_spi_sequence_add(&seq, SPI_FSI_SEQUENCE_SHIFT_OUT(len));

 		if (!list_is_last(&transfer->transfer_list,
 				  &mesg->transfers)) {
 			next = list_next_entry(transfer, transfer_list);

 			/* Sequencer can only do shift in (rx) after tx. */
 			if (next->rx_buf) {
 				u8 shift;

 				if (next->len > SPI_FSI_MAX_RX_SIZE) {
 					rc = -EINVAL;
 					goto error;
 				}

 				dev_dbg(ctx->dev, "Sequence rx of %d bytes.\n",
 					next->len);

 				shift = SPI_FSI_SEQUENCE_SHIFT_IN(next->len);
 				fsi_spi_sequence_add(&seq, shift);
 			} else {
 				next = NULL;
 			}
 		}

 		fsi_spi_sequence_add(&seq, SPI_FSI_SEQUENCE_SEL_SLAVE(0));

 		rc = fsi_spi_write_reg(ctx, SPI_FSI_SEQUENCE, seq.data);
 		if (rc)
 			goto error;

 		rc = fsi_spi_transfer_data(ctx, transfer);
 		if (rc)
 			goto error;

 		if (next) {
 			rc = fsi_spi_transfer_data(ctx, next);
 			if (rc)
 				goto error;

 			transfer = next;
 		}
 	}

 error:
 	mesg->status = rc;
 	spi_finalize_current_message(ctlr);

 	return rc;
 }

 static size_t fsi_spi_max_transfer_size(struct spi_device *spi)
 {
 	return SPI_FSI_MAX_RX_SIZE;
 }

 static int fsi_spi_probe(struct device *dev)
 {
 	int rc;
 	struct device_node *np;
 	int num_controllers_registered = 0;
 	struct fsi2spi *bridge;
 	struct fsi_device *fsi = to_fsi_dev(dev);

 	rc = fsi_spi_check_mux(fsi, dev);
 	if (rc)
 		return -ENODEV;

 	bridge = devm_kzalloc(dev, sizeof(*bridge), GFP_KERNEL);
 	if (!bridge)
 		return -ENOMEM;

 	bridge->fsi = fsi;
 	mutex_init(&bridge->lock);

 	for_each_available_child_of_node(dev->of_node, np) {
 		u32 base;
 		struct fsi_spi *ctx;
 		struct spi_controller *ctlr;

 		if (of_property_read_u32(np, "reg", &base))
 			continue;

 		ctlr = spi_alloc_host(dev, sizeof(*ctx));
 		if (!ctlr) {
 			of_node_put(np);
 			break;
 		}

 		ctlr->dev.of_node = np;
 		ctlr->num_chipselect = of_get_available_child_count(np) ?: 1;
 		ctlr->flags = SPI_CONTROLLER_HALF_DUPLEX;
 		ctlr->max_transfer_size = fsi_spi_max_transfer_size;
 		ctlr->transfer_one_message = fsi_spi_transfer_one_message;

 		ctx = spi_controller_get_devdata(ctlr);
 		ctx->dev = &ctlr->dev;
 		ctx->bridge = bridge;
 		ctx->base = base + SPI_FSI_BASE;

 		rc = devm_spi_register_controller(dev, ctlr);
 		if (rc)
 			spi_controller_put(ctlr);
 		else
 			num_controllers_registered++;
 	}

 	if (!num_controllers_registered)
 		return -ENODEV;

 	return 0;
 }

 static const struct fsi_device_id fsi_spi_ids[] = {
 	{ FSI_ENGID_SPI, FSI_VERSION_ANY },
 	{ }
 };
 MODULE_DEVICE_TABLE(fsi, fsi_spi_ids);

 static struct fsi_driver fsi_spi_driver = {
 	.id_table = fsi_spi_ids,
 	.drv = {
 		.name = "spi-fsi",
 		.bus = &fsi_bus_type,
 		.probe = fsi_spi_probe,
 	},
 };
 module_fsi_driver(fsi_spi_driver);

 MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
 MODULE_DESCRIPTION("FSI attached SPI controller");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	// Copyright (C) IBM Corporation 2020

	#include <linux/bitfield.h>
	#include <linux/bits.h>
	#include <linux/fsi.h>
	#include <linux/jiffies.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/spi/spi.h>

	#define FSI_ENGID_SPI 0x23
	#define FSI_MBOX_ROOT_CTRL_8 0x2860
	#define FSI_MBOX_ROOT_CTRL_8_SPI_MUX 0xf0000000

	#define FSI2SPI_DATA0 0x00
	#define FSI2SPI_DATA1 0x04
	#define FSI2SPI_CMD 0x08
	#define FSI2SPI_CMD_WRITE BIT(31)
	#define FSI2SPI_RESET 0x18
	#define FSI2SPI_STATUS 0x1c
	#define FSI2SPI_STATUS_ANY_ERROR BIT(31)
	#define FSI2SPI_IRQ 0x20

	#define SPI_FSI_BASE 0x70000
	#define SPI_FSI_TIMEOUT_MS 1000
	#define SPI_FSI_MAX_RX_SIZE 8
	#define SPI_FSI_MAX_TX_SIZE 40

	#define SPI_FSI_ERROR 0x0
	#define SPI_FSI_COUNTER_CFG 0x1
	#define SPI_FSI_CFG1 0x2
	#define SPI_FSI_CLOCK_CFG 0x3
	#define SPI_FSI_CLOCK_CFG_MM_ENABLE BIT_ULL(32)
	#define SPI_FSI_CLOCK_CFG_ECC_DISABLE (BIT_ULL(35) \| BIT_ULL(33))
	#define SPI_FSI_CLOCK_CFG_RESET1 (BIT_ULL(36) \| BIT_ULL(38))
	#define SPI_FSI_CLOCK_CFG_RESET2 (BIT_ULL(37) \| BIT_ULL(39))
	#define SPI_FSI_CLOCK_CFG_MODE (BIT_ULL(41) \| BIT_ULL(42))
	#define SPI_FSI_CLOCK_CFG_SCK_RECV_DEL GENMASK_ULL(51, 44)
	#define SPI_FSI_CLOCK_CFG_SCK_NO_DEL BIT_ULL(51)
	#define SPI_FSI_CLOCK_CFG_SCK_DIV GENMASK_ULL(63, 52)
	#define SPI_FSI_MMAP 0x4
	#define SPI_FSI_DATA_TX 0x5
	#define SPI_FSI_DATA_RX 0x6
	#define SPI_FSI_SEQUENCE 0x7
	#define SPI_FSI_SEQUENCE_STOP 0x00
	#define SPI_FSI_SEQUENCE_SEL_SLAVE(x) (0x10 \| ((x) & 0xf))
	#define SPI_FSI_SEQUENCE_SHIFT_OUT(x) (0x30 \| ((x) & 0xf))
	#define SPI_FSI_SEQUENCE_SHIFT_IN(x) (0x40 \| ((x) & 0xf))
	#define SPI_FSI_SEQUENCE_COPY_DATA_TX 0xc0
	#define SPI_FSI_SEQUENCE_BRANCH(x) (0xe0 \| ((x) & 0xf))
	#define SPI_FSI_STATUS 0x8
	#define SPI_FSI_STATUS_ERROR \
	(GENMASK_ULL(31, 21) \| GENMASK_ULL(15, 12))
	#define SPI_FSI_STATUS_SEQ_STATE GENMASK_ULL(55, 48)
	#define SPI_FSI_STATUS_SEQ_STATE_IDLE BIT_ULL(48)
	#define SPI_FSI_STATUS_TDR_UNDERRUN BIT_ULL(57)
	#define SPI_FSI_STATUS_TDR_OVERRUN BIT_ULL(58)
	#define SPI_FSI_STATUS_TDR_FULL BIT_ULL(59)
	#define SPI_FSI_STATUS_RDR_UNDERRUN BIT_ULL(61)
	#define SPI_FSI_STATUS_RDR_OVERRUN BIT_ULL(62)
	#define SPI_FSI_STATUS_RDR_FULL BIT_ULL(63)
	#define SPI_FSI_STATUS_ANY_ERROR \
	(SPI_FSI_STATUS_ERROR \| \
	SPI_FSI_STATUS_TDR_OVERRUN \| SPI_FSI_STATUS_RDR_UNDERRUN \| \
	SPI_FSI_STATUS_RDR_OVERRUN)
	#define SPI_FSI_PORT_CTRL 0x9

	struct fsi2spi {
	struct fsi_device fsi; / FSI2SPI CFAM engine device */
	struct mutex lock; /* lock access to the device */
	};

	struct fsi_spi {
	struct device dev; / SPI controller device */
	struct fsi2spi bridge; / FSI2SPI device */
	u32 base;
	};

	struct fsi_spi_sequence {
	int bit;
	u64 data;
	};

	static int fsi_spi_check_mux(struct fsi_device fsi, struct device dev)
	{
	int rc;
	u32 root_ctrl_8;
	__be32 root_ctrl_8_be;

	rc = fsi_slave_read(fsi->slave, FSI_MBOX_ROOT_CTRL_8, &root_ctrl_8_be,
	sizeof(root_ctrl_8_be));
	if (rc)
	return rc;

	root_ctrl_8 = be32_to_cpu(root_ctrl_8_be);
	dev_dbg(dev, "Root control register 8: %08x\n", root_ctrl_8);
	if ((root_ctrl_8 & FSI_MBOX_ROOT_CTRL_8_SPI_MUX) ==
	FSI_MBOX_ROOT_CTRL_8_SPI_MUX)
	return 0;

	return -ENOLINK;
	}

	static int fsi_spi_check_status(struct fsi_spi *ctx)
	{
	int rc;
	u32 sts;
	__be32 sts_be;

	rc = fsi_device_read(ctx->bridge->fsi, FSI2SPI_STATUS, &sts_be,
	sizeof(sts_be));
	if (rc)
	return rc;

	sts = be32_to_cpu(sts_be);
	if (sts & FSI2SPI_STATUS_ANY_ERROR) {
	dev_err(ctx->dev, "Error with FSI2SPI interface: %08x.\n", sts);
	return -EIO;
	}

	return 0;
	}

	static int fsi_spi_read_reg(struct fsi_spi ctx, u32 offset, u64 value)
	{
	int rc = 0;
	__be32 cmd_be;
	__be32 data_be;
	u32 cmd = offset + ctx->base;
	struct fsi2spi *bridge = ctx->bridge;

	*value = 0ULL;

	if (cmd & FSI2SPI_CMD_WRITE)
	return -EINVAL;

	rc = mutex_lock_interruptible(&bridge->lock);
	if (rc)
	return rc;

	cmd_be = cpu_to_be32(cmd);
	rc = fsi_device_write(bridge->fsi, FSI2SPI_CMD, &cmd_be,
	sizeof(cmd_be));
	if (rc)
	goto unlock;

	rc = fsi_spi_check_status(ctx);
	if (rc)
	goto unlock;

	rc = fsi_device_read(bridge->fsi, FSI2SPI_DATA0, &data_be,
	sizeof(data_be));
	if (rc)
	goto unlock;

	*value \|= (u64)be32_to_cpu(data_be) << 32;

	rc = fsi_device_read(bridge->fsi, FSI2SPI_DATA1, &data_be,
	sizeof(data_be));
	if (rc)
	goto unlock;

	*value \|= (u64)be32_to_cpu(data_be);
	dev_dbg(ctx->dev, "Read %02x[%016llx].\n", offset, *value);

	unlock:
	mutex_unlock(&bridge->lock);
	return rc;
	}

	static int fsi_spi_write_reg(struct fsi_spi *ctx, u32 offset, u64 value)
	{
	int rc = 0;
	__be32 cmd_be;
	__be32 data_be;
	u32 cmd = offset + ctx->base;
	struct fsi2spi *bridge = ctx->bridge;

	if (cmd & FSI2SPI_CMD_WRITE)
	return -EINVAL;

	rc = mutex_lock_interruptible(&bridge->lock);
	if (rc)
	return rc;

	dev_dbg(ctx->dev, "Write %02x[%016llx].\n", offset, value);

	data_be = cpu_to_be32(upper_32_bits(value));
	rc = fsi_device_write(bridge->fsi, FSI2SPI_DATA0, &data_be,
	sizeof(data_be));
	if (rc)
	goto unlock;

	data_be = cpu_to_be32(lower_32_bits(value));
	rc = fsi_device_write(bridge->fsi, FSI2SPI_DATA1, &data_be,
	sizeof(data_be));
	if (rc)
	goto unlock;

	cmd_be = cpu_to_be32(cmd \| FSI2SPI_CMD_WRITE);
	rc = fsi_device_write(bridge->fsi, FSI2SPI_CMD, &cmd_be,
	sizeof(cmd_be));
	if (rc)
	goto unlock;

	rc = fsi_spi_check_status(ctx);

	unlock:
	mutex_unlock(&bridge->lock);
	return rc;
	}

	static int fsi_spi_data_in(u64 in, u8 *rx, int len)
	{
	int i;
	int num_bytes = min(len, 8);

	for (i = 0; i < num_bytes; ++i)
	rx[i] = (u8)(in >> (8 * ((num_bytes - 1) - i)));

	return num_bytes;
	}

	static int fsi_spi_data_out(u64 out, const u8 tx, int len)
	{
	int i;
	int num_bytes = min(len, 8);
	u8 out_bytes = (u8 )out;

	/* Unused bytes of the tx data should be 0. */
	*out = 0ULL;

	for (i = 0; i < num_bytes; ++i)
	out_bytes[8 - (i + 1)] = tx[i];

	return num_bytes;
	}

	static int fsi_spi_reset(struct fsi_spi *ctx)
	{
	int rc;

	dev_dbg(ctx->dev, "Resetting SPI controller.\n");

	rc = fsi_spi_write_reg(ctx, SPI_FSI_CLOCK_CFG,
	SPI_FSI_CLOCK_CFG_RESET1);
	if (rc)
	return rc;

	rc = fsi_spi_write_reg(ctx, SPI_FSI_CLOCK_CFG,
	SPI_FSI_CLOCK_CFG_RESET2);
	if (rc)
	return rc;

	return fsi_spi_write_reg(ctx, SPI_FSI_STATUS, 0ULL);
	}

	static int fsi_spi_status(struct fsi_spi ctx, u64 status, const char *dir)
	{
	int rc = fsi_spi_read_reg(ctx, SPI_FSI_STATUS, status);

	if (rc)
	return rc;

	if (*status & SPI_FSI_STATUS_ANY_ERROR) {
	dev_err(ctx->dev, "%s error: %016llx\n", dir, *status);

	rc = fsi_spi_reset(ctx);
	if (rc)
	return rc;

	return -EREMOTEIO;
	}

	return 0;
	}

	static void fsi_spi_sequence_add(struct fsi_spi_sequence *seq, u8 val)
	{
	/*
	* Add the next byte of instruction to the 8-byte sequence register.
	* Then decrement the counter so that the next instruction will go in
	* the right place. Return the index of the slot we just filled in the
	* sequence register.
	*/
	seq->data \|= (u64)val << seq->bit;
	seq->bit -= 8;
	}

	static void fsi_spi_sequence_init(struct fsi_spi_sequence *seq)
	{
	seq->bit = 56;
	seq->data = 0ULL;
	}

	static int fsi_spi_transfer_data(struct fsi_spi *ctx,
	struct spi_transfer *transfer)
	{
	int loops;
	int rc = 0;
	unsigned long end;
	u64 status = 0ULL;

	if (transfer->tx_buf) {
	int nb;
	int sent = 0;
	u64 out = 0ULL;
	const u8 *tx = transfer->tx_buf;

	while (transfer->len > sent) {
	nb = fsi_spi_data_out(&out, &tx[sent],
	(int)transfer->len - sent);

	rc = fsi_spi_write_reg(ctx, SPI_FSI_DATA_TX, out);
	if (rc)
	return rc;

	loops = 0;
	end = jiffies + msecs_to_jiffies(SPI_FSI_TIMEOUT_MS);
	do {
	if (loops++ && time_after(jiffies, end))
	return -ETIMEDOUT;

	rc = fsi_spi_status(ctx, &status, "TX");
	if (rc)
	return rc;
	} while (status & SPI_FSI_STATUS_TDR_FULL);

	sent += nb;
	}
	} else if (transfer->rx_buf) {
	int recv = 0;
	u64 in = 0ULL;
	u8 *rx = transfer->rx_buf;

	while (transfer->len > recv) {
	loops = 0;
	end = jiffies + msecs_to_jiffies(SPI_FSI_TIMEOUT_MS);
	do {
	if (loops++ && time_after(jiffies, end))
	return -ETIMEDOUT;

	rc = fsi_spi_status(ctx, &status, "RX");
	if (rc)
	return rc;
	} while (!(status & SPI_FSI_STATUS_RDR_FULL));

	rc = fsi_spi_read_reg(ctx, SPI_FSI_DATA_RX, &in);
	if (rc)
	return rc;

	recv += fsi_spi_data_in(in, &rx[recv],
	(int)transfer->len - recv);
	}
	}

	return 0;
	}

	static int fsi_spi_transfer_init(struct fsi_spi *ctx)
	{
	int loops = 0;
	int rc;
	bool reset = false;
	unsigned long end;
	u64 seq_state;
	u64 clock_cfg = 0ULL;
	u64 status = 0ULL;
	u64 wanted_clock_cfg = SPI_FSI_CLOCK_CFG_ECC_DISABLE \|
	SPI_FSI_CLOCK_CFG_SCK_NO_DEL \|
	FIELD_PREP(SPI_FSI_CLOCK_CFG_SCK_DIV, 19);

	end = jiffies + msecs_to_jiffies(SPI_FSI_TIMEOUT_MS);
	do {
	if (loops++ && time_after(jiffies, end))
	return -ETIMEDOUT;

	rc = fsi_spi_read_reg(ctx, SPI_FSI_STATUS, &status);
	if (rc)
	return rc;

	seq_state = status & SPI_FSI_STATUS_SEQ_STATE;

	if (status & (SPI_FSI_STATUS_ANY_ERROR \|
	SPI_FSI_STATUS_TDR_FULL \|
	SPI_FSI_STATUS_RDR_FULL)) {
	if (reset) {
	dev_err(ctx->dev,
	"Initialization error: %08llx\n",
	status);
	return -EIO;
	}

	rc = fsi_spi_reset(ctx);
	if (rc)
	return rc;

	reset = true;
	continue;
	}
	} while (seq_state && (seq_state != SPI_FSI_STATUS_SEQ_STATE_IDLE));

	rc = fsi_spi_write_reg(ctx, SPI_FSI_COUNTER_CFG, 0ULL);
	if (rc)
	return rc;

	rc = fsi_spi_read_reg(ctx, SPI_FSI_CLOCK_CFG, &clock_cfg);
	if (rc)
	return rc;

	if ((clock_cfg & (SPI_FSI_CLOCK_CFG_MM_ENABLE \|
	SPI_FSI_CLOCK_CFG_ECC_DISABLE \|
	SPI_FSI_CLOCK_CFG_MODE \|
	SPI_FSI_CLOCK_CFG_SCK_RECV_DEL \|
	SPI_FSI_CLOCK_CFG_SCK_DIV)) != wanted_clock_cfg)
	rc = fsi_spi_write_reg(ctx, SPI_FSI_CLOCK_CFG,
	wanted_clock_cfg);

	return rc;
	}

	static int fsi_spi_transfer_one_message(struct spi_controller *ctlr,
	struct spi_message *mesg)
	{
	int rc;
	u8 seq_slave = SPI_FSI_SEQUENCE_SEL_SLAVE(spi_get_chipselect(mesg->spi, 0) + 1);
	unsigned int len;
	struct spi_transfer *transfer;
	struct fsi_spi *ctx = spi_controller_get_devdata(ctlr);

	rc = fsi_spi_check_mux(ctx->bridge->fsi, ctx->dev);
	if (rc)
	goto error;

	list_for_each_entry(transfer, &mesg->transfers, transfer_list) {
	struct fsi_spi_sequence seq;
	struct spi_transfer *next = NULL;

	/* Sequencer must do shift out (tx) first. */
	if (!transfer->tx_buf \|\| transfer->len > SPI_FSI_MAX_TX_SIZE) {
	rc = -EINVAL;
	goto error;
	}

	dev_dbg(ctx->dev, "Start tx of %d bytes.\n", transfer->len);

	rc = fsi_spi_transfer_init(ctx);
	if (rc < 0)
	goto error;

	fsi_spi_sequence_init(&seq);
	fsi_spi_sequence_add(&seq, seq_slave);

	len = transfer->len;
	while (len > 8) {
	fsi_spi_sequence_add(&seq,
	SPI_FSI_SEQUENCE_SHIFT_OUT(8));
	len -= 8;
	}
	fsi_spi_sequence_add(&seq, SPI_FSI_SEQUENCE_SHIFT_OUT(len));

	if (!list_is_last(&transfer->transfer_list,
	&mesg->transfers)) {
	next = list_next_entry(transfer, transfer_list);

	/* Sequencer can only do shift in (rx) after tx. */
	if (next->rx_buf) {
	u8 shift;

	if (next->len > SPI_FSI_MAX_RX_SIZE) {
	rc = -EINVAL;
	goto error;
	}

	dev_dbg(ctx->dev, "Sequence rx of %d bytes.\n",
	next->len);

	shift = SPI_FSI_SEQUENCE_SHIFT_IN(next->len);
	fsi_spi_sequence_add(&seq, shift);
	} else {
	next = NULL;
	}
	}

	fsi_spi_sequence_add(&seq, SPI_FSI_SEQUENCE_SEL_SLAVE(0));

	rc = fsi_spi_write_reg(ctx, SPI_FSI_SEQUENCE, seq.data);
	if (rc)
	goto error;

	rc = fsi_spi_transfer_data(ctx, transfer);
	if (rc)
	goto error;

	if (next) {
	rc = fsi_spi_transfer_data(ctx, next);
	if (rc)
	goto error;

	transfer = next;
	}
	}

	error:
	mesg->status = rc;
	spi_finalize_current_message(ctlr);

	return rc;
	}

	static size_t fsi_spi_max_transfer_size(struct spi_device *spi)
	{
	return SPI_FSI_MAX_RX_SIZE;
	}

	static int fsi_spi_probe(struct device *dev)
	{
	int rc;
	struct device_node *np;
	int num_controllers_registered = 0;
	struct fsi2spi *bridge;
	struct fsi_device *fsi = to_fsi_dev(dev);

	rc = fsi_spi_check_mux(fsi, dev);
	if (rc)
	return -ENODEV;

	bridge = devm_kzalloc(dev, sizeof(*bridge), GFP_KERNEL);
	if (!bridge)
	return -ENOMEM;

	bridge->fsi = fsi;
	mutex_init(&bridge->lock);

	for_each_available_child_of_node(dev->of_node, np) {
	u32 base;
	struct fsi_spi *ctx;
	struct spi_controller *ctlr;

	if (of_property_read_u32(np, "reg", &base))
	continue;

	ctlr = spi_alloc_host(dev, sizeof(*ctx));
	if (!ctlr) {
	of_node_put(np);
	break;
	}

	ctlr->dev.of_node = np;
	ctlr->num_chipselect = of_get_available_child_count(np) ?: 1;
	ctlr->flags = SPI_CONTROLLER_HALF_DUPLEX;
	ctlr->max_transfer_size = fsi_spi_max_transfer_size;
	ctlr->transfer_one_message = fsi_spi_transfer_one_message;

	ctx = spi_controller_get_devdata(ctlr);
	ctx->dev = &ctlr->dev;
	ctx->bridge = bridge;
	ctx->base = base + SPI_FSI_BASE;

	rc = devm_spi_register_controller(dev, ctlr);
	if (rc)
	spi_controller_put(ctlr);
	else
	num_controllers_registered++;
	}

	if (!num_controllers_registered)
	return -ENODEV;

	return 0;
	}

	static const struct fsi_device_id fsi_spi_ids[] = {
	{ FSI_ENGID_SPI, FSI_VERSION_ANY },
	{ }
	};
	MODULE_DEVICE_TABLE(fsi, fsi_spi_ids);

	static struct fsi_driver fsi_spi_driver = {
	.id_table = fsi_spi_ids,
	.drv = {
	.name = "spi-fsi",
	.bus = &fsi_bus_type,
	.probe = fsi_spi_probe,
	},
	};
	module_fsi_driver(fsi_spi_driver);

	MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
	MODULE_DESCRIPTION("FSI attached SPI controller");
	MODULE_LICENSE("GPL");