// SPDX-License-Identifier: GPL-2.0+
// Copyright 2018 IBM Corp
/*
 * A FSI master based on Aspeed ColdFire coprocessor
 */

#include <linux/crc4.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/fsi.h>
#include <linux/gpio/consumer.h>
#include <linux/io.h>
#include <linux/irqflags.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/regmap.h>
#include <linux/firmware.h>
#include <linux/gpio/aspeed.h>
#include <linux/mfd/syscon.h>
#include <linux/of_address.h>
#include <linux/genalloc.h>

#include "fsi-master.h"
#include "cf-fsi-fw.h"

#define FW_FILE_NAME	"cf-fsi-fw.bin"

/* Common SCU based coprocessor control registers */
#define SCU_COPRO_CTRL			0x100
#define   SCU_COPRO_RESET			0x00000002
#define   SCU_COPRO_CLK_EN			0x00000001

/* AST2500 specific ones */
#define SCU_2500_COPRO_SEG0		0x104
#define SCU_2500_COPRO_SEG1		0x108
#define SCU_2500_COPRO_SEG2		0x10c
#define SCU_2500_COPRO_SEG3		0x110
#define SCU_2500_COPRO_SEG4		0x114
#define SCU_2500_COPRO_SEG5		0x118
#define SCU_2500_COPRO_SEG6		0x11c
#define SCU_2500_COPRO_SEG7		0x120
#define SCU_2500_COPRO_SEG8		0x124
#define   SCU_2500_COPRO_SEG_SWAP		0x00000001
#define SCU_2500_COPRO_CACHE_CTL	0x128
#define   SCU_2500_COPRO_CACHE_EN		0x00000001
#define   SCU_2500_COPRO_SEG0_CACHE_EN		0x00000002
#define   SCU_2500_COPRO_SEG1_CACHE_EN		0x00000004
#define   SCU_2500_COPRO_SEG2_CACHE_EN		0x00000008
#define   SCU_2500_COPRO_SEG3_CACHE_EN		0x00000010
#define   SCU_2500_COPRO_SEG4_CACHE_EN		0x00000020
#define   SCU_2500_COPRO_SEG5_CACHE_EN		0x00000040
#define   SCU_2500_COPRO_SEG6_CACHE_EN		0x00000080
#define   SCU_2500_COPRO_SEG7_CACHE_EN		0x00000100
#define   SCU_2500_COPRO_SEG8_CACHE_EN		0x00000200

#define SCU_2400_COPRO_SEG0		0x104
#define SCU_2400_COPRO_SEG2		0x108
#define SCU_2400_COPRO_SEG4		0x10c
#define SCU_2400_COPRO_SEG6		0x110
#define SCU_2400_COPRO_SEG8		0x114
#define   SCU_2400_COPRO_SEG_SWAP		0x80000000
#define SCU_2400_COPRO_CACHE_CTL	0x118
#define   SCU_2400_COPRO_CACHE_EN		0x00000001
#define   SCU_2400_COPRO_SEG0_CACHE_EN		0x00000002
#define   SCU_2400_COPRO_SEG2_CACHE_EN		0x00000004
#define   SCU_2400_COPRO_SEG4_CACHE_EN		0x00000008
#define   SCU_2400_COPRO_SEG6_CACHE_EN		0x00000010
#define   SCU_2400_COPRO_SEG8_CACHE_EN		0x00000020

/* CVIC registers */
#define CVIC_EN_REG			0x10
#define CVIC_TRIG_REG			0x18

/*
 * System register base address (needed for configuring the
 * coldfire maps)
 */
#define SYSREG_BASE			0x1e600000

/* Amount of SRAM required */
#define SRAM_SIZE			0x1000

#define LAST_ADDR_INVALID		0x1

struct fsi_master_acf {
	struct fsi_master	master;
	struct device		*dev;
	struct regmap		*scu;
	struct mutex		lock;	/* mutex for command ordering */
	struct gpio_desc	*gpio_clk;
	struct gpio_desc	*gpio_data;
	struct gpio_desc	*gpio_trans;	/* Voltage translator */
	struct gpio_desc	*gpio_enable;	/* FSI enable */
	struct gpio_desc	*gpio_mux;	/* Mux control */
	uint16_t		gpio_clk_vreg;
	uint16_t		gpio_clk_dreg;
	uint16_t       		gpio_dat_vreg;
	uint16_t       		gpio_dat_dreg;
	uint16_t       		gpio_tra_vreg;
	uint16_t       		gpio_tra_dreg;
	uint8_t			gpio_clk_bit;
	uint8_t			gpio_dat_bit;
	uint8_t			gpio_tra_bit;
	uint32_t		cf_mem_addr;
	size_t			cf_mem_size;
	void __iomem		*cf_mem;
	void __iomem		*cvic;
	struct gen_pool		*sram_pool;
	void __iomem		*sram;
	bool			is_ast2500;
	bool			external_mode;
	bool			trace_enabled;
	uint32_t		last_addr;
	uint8_t			t_send_delay;
	uint8_t			t_echo_delay;
	uint32_t		cvic_sw_irq;
};
#define to_fsi_master_acf(m) container_of(m, struct fsi_master_acf, master)

struct fsi_msg {
	uint64_t	msg;
	uint8_t		bits;
};

#define CREATE_TRACE_POINTS
#include <trace/events/fsi_master_ast_cf.h>

static void msg_push_bits(struct fsi_msg *msg, uint64_t data, int bits)
{
	msg->msg <<= bits;
	msg->msg |= data & ((1ull << bits) - 1);
	msg->bits += bits;
}

static void msg_push_crc(struct fsi_msg *msg)
{
	uint8_t crc;
	int top;

	top = msg->bits & 0x3;

	/* start bit, and any non-aligned top bits */
	crc = crc4(0, 1 << top | msg->msg >> (msg->bits - top), top + 1);

	/* aligned bits */
	crc = crc4(crc, msg->msg, msg->bits - top);

	msg_push_bits(msg, crc, 4);
}

static void msg_finish_cmd(struct fsi_msg *cmd)
{
	/* Left align message */
	cmd->msg <<= (64 - cmd->bits);
}

static bool check_same_address(struct fsi_master_acf *master, int id,
			       uint32_t addr)
{
	/* this will also handle LAST_ADDR_INVALID */
	return master->last_addr == (((id & 0x3) << 21) | (addr & ~0x3));
}

static bool check_relative_address(struct fsi_master_acf *master, int id,
				   uint32_t addr, uint32_t *rel_addrp)
{
	uint32_t last_addr = master->last_addr;
	int32_t rel_addr;

	if (last_addr == LAST_ADDR_INVALID)
		return false;

	/* We may be in 23-bit addressing mode, which uses the id as the
	 * top two address bits. So, if we're referencing a different ID,
	 * use absolute addresses.
	 */
	if (((last_addr >> 21) & 0x3) != id)
		return false;

	/* remove the top two bits from any 23-bit addressing */
	last_addr &= (1 << 21) - 1;

	/* We know that the addresses are limited to 21 bits, so this won't
	 * overflow the signed rel_addr */
	rel_addr = addr - last_addr;
	if (rel_addr > 255 || rel_addr < -256)
		return false;

	*rel_addrp = (uint32_t)rel_addr;

	return true;
}

static void last_address_update(struct fsi_master_acf *master,
				int id, bool valid, uint32_t addr)
{
	if (!valid)
		master->last_addr = LAST_ADDR_INVALID;
	else
		master->last_addr = ((id & 0x3) << 21) | (addr & ~0x3);
}

/*
 * Encode an Absolute/Relative/Same Address command
 */
static void build_ar_command(struct fsi_master_acf *master,
			     struct fsi_msg *cmd, uint8_t id,
			     uint32_t addr, size_t size,
			     const void *data)
{
	int i, addr_bits, opcode_bits;
	bool write = !!data;
	uint8_t ds, opcode;
	uint32_t rel_addr;

	cmd->bits = 0;
	cmd->msg = 0;

	/* we have 21 bits of address max */
	addr &= ((1 << 21) - 1);

	/* cmd opcodes are variable length - SAME_AR is only two bits */
	opcode_bits = 3;

	if (check_same_address(master, id, addr)) {
		/* we still address the byte offset within the word */
		addr_bits = 2;
		opcode_bits = 2;
		opcode = FSI_CMD_SAME_AR;
		trace_fsi_master_acf_cmd_same_addr(master);

	} else if (check_relative_address(master, id, addr, &rel_addr)) {
		/* 8 bits plus sign */
		addr_bits = 9;
		addr = rel_addr;
		opcode = FSI_CMD_REL_AR;
		trace_fsi_master_acf_cmd_rel_addr(master, rel_addr);

	} else {
		addr_bits = 21;
		opcode = FSI_CMD_ABS_AR;
		trace_fsi_master_acf_cmd_abs_addr(master, addr);
	}

	/*
	 * The read/write size is encoded in the lower bits of the address
	 * (as it must be naturally-aligned), and the following ds bit.
	 *
	 *	size	addr:1	addr:0	ds
	 *	1	x	x	0
	 *	2	x	0	1
	 *	4	0	1	1
	 *
	 */
	ds = size > 1 ? 1 : 0;
	addr &= ~(size - 1);
	if (size == 4)
		addr |= 1;

	msg_push_bits(cmd, id, 2);
	msg_push_bits(cmd, opcode, opcode_bits);
	msg_push_bits(cmd, write ? 0 : 1, 1);
	msg_push_bits(cmd, addr, addr_bits);
	msg_push_bits(cmd, ds, 1);
	for (i = 0; write && i < size; i++)
		msg_push_bits(cmd, ((uint8_t *)data)[i], 8);

	msg_push_crc(cmd);
	msg_finish_cmd(cmd);
}

static void build_dpoll_command(struct fsi_msg *cmd, uint8_t slave_id)
{
	cmd->bits = 0;
	cmd->msg = 0;

	msg_push_bits(cmd, slave_id, 2);
	msg_push_bits(cmd, FSI_CMD_DPOLL, 3);
	msg_push_crc(cmd);
	msg_finish_cmd(cmd);
}

static void build_epoll_command(struct fsi_msg *cmd, uint8_t slave_id)
{
	cmd->bits = 0;
	cmd->msg = 0;

	msg_push_bits(cmd, slave_id, 2);
	msg_push_bits(cmd, FSI_CMD_EPOLL, 3);
	msg_push_crc(cmd);
	msg_finish_cmd(cmd);
}

static void build_term_command(struct fsi_msg *cmd, uint8_t slave_id)
{
	cmd->bits = 0;
	cmd->msg = 0;

	msg_push_bits(cmd, slave_id, 2);
	msg_push_bits(cmd, FSI_CMD_TERM, 6);
	msg_push_crc(cmd);
	msg_finish_cmd(cmd);
}

static int do_copro_command(struct fsi_master_acf *master, uint32_t op)
{
	uint32_t timeout = 10000000;
	uint8_t stat;

	trace_fsi_master_acf_copro_command(master, op);

	/* Send command */
	iowrite32be(op, master->sram + CMD_STAT_REG);

	/* Ring doorbell if any */
	if (master->cvic)
		iowrite32(0x2, master->cvic + CVIC_TRIG_REG);

	/* Wait for status to indicate completion (or error) */
	do {
		if (timeout-- == 0) {
			dev_warn(master->dev,
				 "Timeout waiting for coprocessor completion\n");
			return -ETIMEDOUT;
		}
		stat = ioread8(master->sram + CMD_STAT_REG);
	} while(stat < STAT_COMPLETE || stat == 0xff);

	if (stat == STAT_COMPLETE)
		return 0;
	switch(stat) {
	case STAT_ERR_INVAL_CMD:
		return -EINVAL;
	case STAT_ERR_INVAL_IRQ:
		return -EIO;
	case STAT_ERR_MTOE:
		return -ESHUTDOWN;
	}
	return -ENXIO;
}

static int clock_zeros(struct fsi_master_acf *master, int count)
{
	while (count) {
		int rc, lcnt = min(count, 255);

		rc = do_copro_command(master,
				      CMD_IDLE_CLOCKS | (lcnt << CMD_REG_CLEN_SHIFT));
		if (rc)
			return rc;
		count -= lcnt;
	}
	return 0;
}

static int send_request(struct fsi_master_acf *master, struct fsi_msg *cmd,
			unsigned int resp_bits)
{
	uint32_t op;

	trace_fsi_master_acf_send_request(master, cmd, resp_bits);

	/* Store message into SRAM */
	iowrite32be((cmd->msg >> 32), master->sram + CMD_DATA);
	iowrite32be((cmd->msg & 0xffffffff), master->sram + CMD_DATA + 4);

	op = CMD_COMMAND;
	op |= cmd->bits << CMD_REG_CLEN_SHIFT;
	if (resp_bits)
		op |= resp_bits << CMD_REG_RLEN_SHIFT;

	return do_copro_command(master, op);
}

static int read_copro_response(struct fsi_master_acf *master, uint8_t size,
			       uint32_t *response, u8 *tag)
{
	uint8_t rtag = ioread8(master->sram + STAT_RTAG) & 0xf;
	uint8_t rcrc = ioread8(master->sram + STAT_RCRC) & 0xf;
	uint32_t rdata = 0;
	uint32_t crc;
	uint8_t ack;

	*tag = ack = rtag & 3;

	/* we have a whole message now; check CRC */
	crc = crc4(0, 1, 1);
	crc = crc4(crc, rtag, 4);
	if (ack == FSI_RESP_ACK && size) {
		rdata = ioread32be(master->sram + RSP_DATA);
		crc = crc4(crc, rdata, size);
		if (response)
			*response = rdata;
	}
	crc = crc4(crc, rcrc, 4);

	trace_fsi_master_acf_copro_response(master, rtag, rcrc, rdata, crc == 0);

	if (crc) {
		/*
		 * Check if it's all 1's or all 0's, that probably means
		 * the host is off
		 */
		if ((rtag == 0xf && rcrc == 0xf) || (rtag == 0 && rcrc == 0))
			return -ENODEV;
		dev_dbg(master->dev, "Bad response CRC !\n");
		return -EAGAIN;
	}
	return 0;
}

static int send_term(struct fsi_master_acf *master, uint8_t slave)
{
	struct fsi_msg cmd;
	uint8_t tag;
	int rc;

	build_term_command(&cmd, slave);

	rc = send_request(master, &cmd, 0);
	if (rc) {
		dev_warn(master->dev, "Error %d sending term\n", rc);
		return rc;
	}

	rc = read_copro_response(master, 0, NULL, &tag);
	if (rc < 0) {
		dev_err(master->dev,
				"TERM failed; lost communication with slave\n");
		return -EIO;
	} else if (tag != FSI_RESP_ACK) {
		dev_err(master->dev, "TERM failed; response %d\n", tag);
		return -EIO;
	}
	return 0;
}

static void dump_ucode_trace(struct fsi_master_acf *master)
{
	char trbuf[52];
	char *p;
	int i;

	dev_dbg(master->dev,
		"CMDSTAT:%08x RTAG=%02x RCRC=%02x RDATA=%02x #INT=%08x\n",
		ioread32be(master->sram + CMD_STAT_REG),
		ioread8(master->sram + STAT_RTAG),
		ioread8(master->sram + STAT_RCRC),
		ioread32be(master->sram + RSP_DATA),
		ioread32be(master->sram + INT_CNT));

	for (i = 0; i < 512; i++) {
		uint8_t v;
		if ((i % 16) == 0)
			p = trbuf;
		v = ioread8(master->sram + TRACEBUF + i);
		p += sprintf(p, "%02x ", v);
		if (((i % 16) == 15) || v == TR_END)
			dev_dbg(master->dev, "%s\n", trbuf);
		if (v == TR_END)
			break;
	}
}

static int handle_response(struct fsi_master_acf *master,
			   uint8_t slave, uint8_t size, void *data)
{
	int busy_count = 0, rc;
	int crc_err_retries = 0;
	struct fsi_msg cmd;
	uint32_t response;
	uint8_t tag;
retry:
	rc = read_copro_response(master, size, &response, &tag);

	/* Handle retries on CRC errors */
	if (rc == -EAGAIN) {
		/* Too many retries ? */
		if (crc_err_retries++ > FSI_CRC_ERR_RETRIES) {
			/*
			 * Pass it up as a -EIO otherwise upper level will retry
			 * the whole command which isn't what we want here.
			 */
			rc = -EIO;
			goto bail;
		}
		trace_fsi_master_acf_crc_rsp_error(master, crc_err_retries);
		if (master->trace_enabled)
			dump_ucode_trace(master);
		rc = clock_zeros(master, FSI_MASTER_EPOLL_CLOCKS);
		if (rc) {
			dev_warn(master->dev,
				 "Error %d clocking zeros for E_POLL\n", rc);
			return rc;
		}
		build_epoll_command(&cmd, slave);
		rc = send_request(master, &cmd, size);
		if (rc) {
			dev_warn(master->dev, "Error %d sending E_POLL\n", rc);
			return -EIO;
		}
		goto retry;
	}
	if (rc)
		return rc;

	switch (tag) {
	case FSI_RESP_ACK:
		if (size && data) {
			if (size == 32)
				*(__be32 *)data = cpu_to_be32(response);
			else if (size == 16)
				*(__be16 *)data = cpu_to_be16(response);
			else
				*(u8 *)data = response;
		}
		break;
	case FSI_RESP_BUSY:
		/*
		 * Its necessary to clock slave before issuing
		 * d-poll, not indicated in the hardware protocol
		 * spec. < 20 clocks causes slave to hang, 21 ok.
		 */
		dev_dbg(master->dev, "Busy, retrying...\n");
		if (master->trace_enabled)
			dump_ucode_trace(master);
		rc = clock_zeros(master, FSI_MASTER_DPOLL_CLOCKS);
		if (rc) {
			dev_warn(master->dev,
				 "Error %d clocking zeros for D_POLL\n", rc);
			break;
		}
		if (busy_count++ < FSI_MASTER_MAX_BUSY) {
			build_dpoll_command(&cmd, slave);
			rc = send_request(master, &cmd, size);
			if (rc) {
				dev_warn(master->dev, "Error %d sending D_POLL\n", rc);
				break;
			}
			goto retry;
		}
		dev_dbg(master->dev,
			"ERR slave is stuck in busy state, issuing TERM\n");
		send_term(master, slave);
		rc = -EIO;
		break;

	case FSI_RESP_ERRA:
		dev_dbg(master->dev, "ERRA received\n");
		if (master->trace_enabled)
			dump_ucode_trace(master);
		rc = -EIO;
		break;
	case FSI_RESP_ERRC:
		dev_dbg(master->dev, "ERRC received\n");
		if (master->trace_enabled)
			dump_ucode_trace(master);
		rc = -EAGAIN;
		break;
	}
 bail:
	if (busy_count > 0) {
		trace_fsi_master_acf_poll_response_busy(master, busy_count);
	}

	return rc;
}

static int fsi_master_acf_xfer(struct fsi_master_acf *master, uint8_t slave,
			       struct fsi_msg *cmd, size_t resp_len, void *resp)
{
	int rc = -EAGAIN, retries = 0;

	resp_len <<= 3;
	while ((retries++) < FSI_CRC_ERR_RETRIES) {
		rc = send_request(master, cmd, resp_len);
		if (rc) {
			if (rc != -ESHUTDOWN)
				dev_warn(master->dev, "Error %d sending command\n", rc);
			break;
		}
		rc = handle_response(master, slave, resp_len, resp);
		if (rc != -EAGAIN)
			break;
		rc = -EIO;
		dev_dbg(master->dev, "ECRC retry %d\n", retries);

		/* Pace it a bit before retry */
		msleep(1);
	}

	return rc;
}

static int fsi_master_acf_read(struct fsi_master *_master, int link,
			       uint8_t id, uint32_t addr, void *val,
			       size_t size)
{
	struct fsi_master_acf *master = to_fsi_master_acf(_master);
	struct fsi_msg cmd;
	int rc;

	if (link != 0)
		return -ENODEV;

	mutex_lock(&master->lock);
	dev_dbg(master->dev, "read id %d addr %x size %zd\n", id, addr, size);
	build_ar_command(master, &cmd, id, addr, size, NULL);
	rc = fsi_master_acf_xfer(master, id, &cmd, size, val);
	last_address_update(master, id, rc == 0, addr);
	if (rc)
		dev_dbg(master->dev, "read id %d addr 0x%08x err: %d\n",
			id, addr, rc);
	mutex_unlock(&master->lock);

	return rc;
}

static int fsi_master_acf_write(struct fsi_master *_master, int link,
				uint8_t id, uint32_t addr, const void *val,
				size_t size)
{
	struct fsi_master_acf *master = to_fsi_master_acf(_master);
	struct fsi_msg cmd;
	int rc;

	if (link != 0)
		return -ENODEV;

	mutex_lock(&master->lock);
	build_ar_command(master, &cmd, id, addr, size, val);
	dev_dbg(master->dev, "write id %d addr %x size %zd raw_data: %08x\n",
		id, addr, size, *(uint32_t *)val);
	rc = fsi_master_acf_xfer(master, id, &cmd, 0, NULL);
	last_address_update(master, id, rc == 0, addr);
	if (rc)
		dev_dbg(master->dev, "write id %d addr 0x%08x err: %d\n",
			id, addr, rc);
	mutex_unlock(&master->lock);

	return rc;
}

static int fsi_master_acf_term(struct fsi_master *_master,
			       int link, uint8_t id)
{
	struct fsi_master_acf *master = to_fsi_master_acf(_master);
	struct fsi_msg cmd;
	int rc;

	if (link != 0)
		return -ENODEV;

	mutex_lock(&master->lock);
	build_term_command(&cmd, id);
	dev_dbg(master->dev, "term id %d\n", id);
	rc = fsi_master_acf_xfer(master, id, &cmd, 0, NULL);
	last_address_update(master, id, false, 0);
	mutex_unlock(&master->lock);

	return rc;
}

static int fsi_master_acf_break(struct fsi_master *_master, int link)
{
	struct fsi_master_acf *master = to_fsi_master_acf(_master);
	int rc;

	if (link != 0)
		return -ENODEV;

	mutex_lock(&master->lock);
	if (master->external_mode) {
		mutex_unlock(&master->lock);
		return -EBUSY;
	}
	dev_dbg(master->dev, "sending BREAK\n");
	rc = do_copro_command(master, CMD_BREAK);
	last_address_update(master, 0, false, 0);
	mutex_unlock(&master->lock);

	/* Wait for logic reset to take effect */
	udelay(200);

	return rc;
}

static void reset_cf(struct fsi_master_acf *master)
{
	regmap_write(master->scu, SCU_COPRO_CTRL, SCU_COPRO_RESET);
	usleep_range(20,20);
	regmap_write(master->scu, SCU_COPRO_CTRL, 0);
	usleep_range(20,20);
}

static void start_cf(struct fsi_master_acf *master)
{
	regmap_write(master->scu, SCU_COPRO_CTRL, SCU_COPRO_CLK_EN);
}

static void setup_ast2500_cf_maps(struct fsi_master_acf *master)
{
	/*
	 * Note about byteswap setting: the bus is wired backwards,
	 * so setting the byteswap bit actually makes the ColdFire
	 * work "normally" for a BE processor, ie, put the MSB in
	 * the lowest address byte.
	 *
	 * We thus need to set the bit for our main memory which
	 * contains our program code. We create two mappings for
	 * the register, one with each setting.
	 *
	 * Segments 2 and 3 has a "swapped" mapping (BE)
	 * and 6 and 7 have a non-swapped mapping (LE) which allows
	 * us to avoid byteswapping register accesses since the
	 * registers are all LE.
	 */

	/* Setup segment 0 to our memory region */
	regmap_write(master->scu, SCU_2500_COPRO_SEG0, master->cf_mem_addr |
		     SCU_2500_COPRO_SEG_SWAP);

	/* Segments 2 and 3 to sysregs with byteswap (for SRAM) */
	regmap_write(master->scu, SCU_2500_COPRO_SEG2, SYSREG_BASE |
		     SCU_2500_COPRO_SEG_SWAP);
	regmap_write(master->scu, SCU_2500_COPRO_SEG3, SYSREG_BASE | 0x100000 |
		     SCU_2500_COPRO_SEG_SWAP);

	/* And segment 6 and 7 to sysregs no byteswap */
	regmap_write(master->scu, SCU_2500_COPRO_SEG6, SYSREG_BASE);
	regmap_write(master->scu, SCU_2500_COPRO_SEG7, SYSREG_BASE | 0x100000);

	/* Memory cachable, regs and SRAM not cachable */
	regmap_write(master->scu, SCU_2500_COPRO_CACHE_CTL,
		     SCU_2500_COPRO_SEG0_CACHE_EN | SCU_2500_COPRO_CACHE_EN);
}

static void setup_ast2400_cf_maps(struct fsi_master_acf *master)
{
	/* Setup segment 0 to our memory region */
	regmap_write(master->scu, SCU_2400_COPRO_SEG0, master->cf_mem_addr |
		     SCU_2400_COPRO_SEG_SWAP);

	/* Segments 2 to sysregs with byteswap (for SRAM) */
	regmap_write(master->scu, SCU_2400_COPRO_SEG2, SYSREG_BASE |
		     SCU_2400_COPRO_SEG_SWAP);

	/* And segment 6 to sysregs no byteswap */
	regmap_write(master->scu, SCU_2400_COPRO_SEG6, SYSREG_BASE);

	/* Memory cachable, regs and SRAM not cachable */
	regmap_write(master->scu, SCU_2400_COPRO_CACHE_CTL,
		     SCU_2400_COPRO_SEG0_CACHE_EN | SCU_2400_COPRO_CACHE_EN);
}

static void setup_common_fw_config(struct fsi_master_acf *master,
				   void __iomem *base)
{
	iowrite16be(master->gpio_clk_vreg, base + HDR_CLOCK_GPIO_VADDR);
	iowrite16be(master->gpio_clk_dreg, base + HDR_CLOCK_GPIO_DADDR);
	iowrite16be(master->gpio_dat_vreg, base + HDR_DATA_GPIO_VADDR);
	iowrite16be(master->gpio_dat_dreg, base + HDR_DATA_GPIO_DADDR);
	iowrite16be(master->gpio_tra_vreg, base + HDR_TRANS_GPIO_VADDR);
	iowrite16be(master->gpio_tra_dreg, base + HDR_TRANS_GPIO_DADDR);
	iowrite8(master->gpio_clk_bit, base + HDR_CLOCK_GPIO_BIT);
	iowrite8(master->gpio_dat_bit, base + HDR_DATA_GPIO_BIT);
	iowrite8(master->gpio_tra_bit, base + HDR_TRANS_GPIO_BIT);
}

static void setup_ast2500_fw_config(struct fsi_master_acf *master)
{
	void __iomem *base = master->cf_mem + HDR_OFFSET;

	setup_common_fw_config(master, base);
	iowrite32be(FW_CONTROL_USE_STOP, base + HDR_FW_CONTROL);
}

static void setup_ast2400_fw_config(struct fsi_master_acf *master)
{
	void __iomem *base = master->cf_mem + HDR_OFFSET;

	setup_common_fw_config(master, base);
	iowrite32be(FW_CONTROL_CONT_CLOCK|FW_CONTROL_DUMMY_RD, base + HDR_FW_CONTROL);
}

static int setup_gpios_for_copro(struct fsi_master_acf *master)
{

	int rc;

	/* This aren't under ColdFire control, just set them up appropriately */
	gpiod_direction_output(master->gpio_mux, 1);
	gpiod_direction_output(master->gpio_enable, 1);

	/* Those are under ColdFire control, let it configure them */
	rc = aspeed_gpio_copro_grab_gpio(master->gpio_clk, &master->gpio_clk_vreg,
					 &master->gpio_clk_dreg, &master->gpio_clk_bit);
	if (rc) {
		dev_err(master->dev, "failed to assign clock gpio to coprocessor\n");
		return rc;
	}
	rc = aspeed_gpio_copro_grab_gpio(master->gpio_data, &master->gpio_dat_vreg,
					 &master->gpio_dat_dreg, &master->gpio_dat_bit);
	if (rc) {
		dev_err(master->dev, "failed to assign data gpio to coprocessor\n");
		aspeed_gpio_copro_release_gpio(master->gpio_clk);
		return rc;
	}
	rc = aspeed_gpio_copro_grab_gpio(master->gpio_trans, &master->gpio_tra_vreg,
					 &master->gpio_tra_dreg, &master->gpio_tra_bit);
	if (rc) {
		dev_err(master->dev, "failed to assign trans gpio to coprocessor\n");
		aspeed_gpio_copro_release_gpio(master->gpio_clk);
		aspeed_gpio_copro_release_gpio(master->gpio_data);
		return rc;
	}
	return 0;
}

static void release_copro_gpios(struct fsi_master_acf *master)
{
	aspeed_gpio_copro_release_gpio(master->gpio_clk);
	aspeed_gpio_copro_release_gpio(master->gpio_data);
	aspeed_gpio_copro_release_gpio(master->gpio_trans);
}

static int load_copro_firmware(struct fsi_master_acf *master)
{
	const struct firmware *fw;
	uint16_t sig = 0, wanted_sig;
	const u8 *data;
	size_t size = 0;
	int rc;

	/* Get the binary */
	rc = request_firmware(&fw, FW_FILE_NAME, master->dev);
	if (rc) {
		dev_err(
			master->dev, "Error %d to load firmware '%s' !\n",
			rc, FW_FILE_NAME);
		return rc;
	}

	/* Which image do we want ? (shared vs. split clock/data GPIOs) */
	if (master->gpio_clk_vreg == master->gpio_dat_vreg)
		wanted_sig = SYS_SIG_SHARED;
	else
		wanted_sig = SYS_SIG_SPLIT;
	dev_dbg(master->dev, "Looking for image sig %04x\n", wanted_sig);

	/* Try to find it */
	for (data = fw->data; data < (fw->data + fw->size);) {
		sig = be16_to_cpup((__be16 *)(data + HDR_OFFSET + HDR_SYS_SIG));
		size = be32_to_cpup((__be32 *)(data + HDR_OFFSET + HDR_FW_SIZE));
		if (sig == wanted_sig)
			break;
		data += size;
	}
	if (sig != wanted_sig) {
		dev_err(master->dev, "Failed to locate image sig %04x in FW blob\n",
			wanted_sig);
		rc = -ENODEV;
		goto release_fw;
	}
	if (size > master->cf_mem_size) {
		dev_err(master->dev, "FW size (%zd) bigger than memory reserve (%zd)\n",
			fw->size, master->cf_mem_size);
		rc = -ENOMEM;
	} else {
		memcpy_toio(master->cf_mem, data, size);
	}

release_fw:
	release_firmware(fw);
	return rc;
}

static int check_firmware_image(struct fsi_master_acf *master)
{
	uint32_t fw_vers, fw_api, fw_options;

	fw_vers = ioread16be(master->cf_mem + HDR_OFFSET + HDR_FW_VERS);
	fw_api = ioread16be(master->cf_mem + HDR_OFFSET + HDR_API_VERS);
	fw_options = ioread32be(master->cf_mem + HDR_OFFSET + HDR_FW_OPTIONS);
	master->trace_enabled = !!(fw_options & FW_OPTION_TRACE_EN);

	/* Check version and signature */
	dev_info(master->dev, "ColdFire initialized, firmware v%d API v%d.%d (trace %s)\n",
		 fw_vers, fw_api >> 8, fw_api & 0xff,
		 master->trace_enabled ? "enabled" : "disabled");

	if ((fw_api >> 8) != API_VERSION_MAJ) {
		dev_err(master->dev, "Unsupported coprocessor API version !\n");
		return -ENODEV;
	}

	return 0;
}

static int copro_enable_sw_irq(struct fsi_master_acf *master)
{
	int timeout;
	uint32_t val;

	/*
	 * Enable coprocessor interrupt input. I've had problems getting the
	 * value to stick, so try in a loop
	 */
	for (timeout = 0; timeout < 10; timeout++) {
		iowrite32(0x2, master->cvic + CVIC_EN_REG);
		val = ioread32(master->cvic + CVIC_EN_REG);
		if (val & 2)
			break;
		msleep(1);
	}
	if (!(val & 2)) {
		dev_err(master->dev, "Failed to enable coprocessor interrupt !\n");
		return -ENODEV;
	}
	return 0;
}

static int fsi_master_acf_setup(struct fsi_master_acf *master)
{
	int timeout, rc;
	uint32_t val;

	/* Make sure the ColdFire is stopped  */
	reset_cf(master);

	/*
	 * Clear SRAM. This needs to happen before we setup the GPIOs
	 * as we might start trying to arbitrate as soon as that happens.
	 */
	memset_io(master->sram, 0, SRAM_SIZE);

	/* Configure GPIOs */
	rc = setup_gpios_for_copro(master);
	if (rc)
		return rc;

	/* Load the firmware into the reserved memory */
	rc = load_copro_firmware(master);
	if (rc)
		return rc;

	/* Read signature and check versions */
	rc = check_firmware_image(master);
	if (rc)
		return rc;

	/* Setup coldfire memory map */
	if (master->is_ast2500) {
		setup_ast2500_cf_maps(master);
		setup_ast2500_fw_config(master);
	} else {
		setup_ast2400_cf_maps(master);
		setup_ast2400_fw_config(master);
	}

	/* Start the ColdFire */
	start_cf(master);

	/* Wait for status register to indicate command completion
	 * which signals the initialization is complete
	 */
	for (timeout = 0; timeout < 10; timeout++) {
		val = ioread8(master->sram + CF_STARTED);
		if (val)
			break;
		msleep(1);
	}
	if (!val) {
		dev_err(master->dev, "Coprocessor startup timeout !\n");
		rc = -ENODEV;
		goto err;
	}

	/* Configure echo & send delay */
	iowrite8(master->t_send_delay, master->sram + SEND_DLY_REG);
	iowrite8(master->t_echo_delay, master->sram + ECHO_DLY_REG);

	/* Enable SW interrupt to copro if any */
	if (master->cvic) {
		rc = copro_enable_sw_irq(master);
		if (rc)
			goto err;
	}
	return 0;
 err:
	/* An error occurred, don't leave the coprocessor running */
	reset_cf(master);

	/* Release the GPIOs */
	release_copro_gpios(master);

	return rc;
}


static void fsi_master_acf_terminate(struct fsi_master_acf *master)
{
	unsigned long flags;

	/*
	 * A GPIO arbitration requestion could come in while this is
	 * happening. To avoid problems, we disable interrupts so it
	 * cannot preempt us on this CPU
	 */

	local_irq_save(flags);

	/* Stop the coprocessor */
	reset_cf(master);

	/* We mark the copro not-started */
	iowrite32(0, master->sram + CF_STARTED);

	/* We mark the ARB register as having given up arbitration to
	 * deal with a potential race with the arbitration request
	 */
	iowrite8(ARB_ARM_ACK, master->sram + ARB_REG);

	local_irq_restore(flags);

	/* Return the GPIOs to the ARM */
	release_copro_gpios(master);
}

static void fsi_master_acf_setup_external(struct fsi_master_acf *master)
{
	/* Setup GPIOs for external FSI master (FSP box) */
	gpiod_direction_output(master->gpio_mux, 0);
	gpiod_direction_output(master->gpio_trans, 0);
	gpiod_direction_output(master->gpio_enable, 1);
	gpiod_direction_input(master->gpio_clk);
	gpiod_direction_input(master->gpio_data);
}

static int fsi_master_acf_link_enable(struct fsi_master *_master, int link,
				      bool enable)
{
	struct fsi_master_acf *master = to_fsi_master_acf(_master);
	int rc = -EBUSY;

	if (link != 0)
		return -ENODEV;

	mutex_lock(&master->lock);
	if (!master->external_mode) {
		gpiod_set_value(master->gpio_enable, enable ? 1 : 0);
		rc = 0;
	}
	mutex_unlock(&master->lock);

	return rc;
}

static int fsi_master_acf_link_config(struct fsi_master *_master, int link,
				      u8 t_send_delay, u8 t_echo_delay)
{
	struct fsi_master_acf *master = to_fsi_master_acf(_master);

	if (link != 0)
		return -ENODEV;

	mutex_lock(&master->lock);
	master->t_send_delay = t_send_delay;
	master->t_echo_delay = t_echo_delay;
	dev_dbg(master->dev, "Changing delays: send=%d echo=%d\n",
		t_send_delay, t_echo_delay);
	iowrite8(master->t_send_delay, master->sram + SEND_DLY_REG);
	iowrite8(master->t_echo_delay, master->sram + ECHO_DLY_REG);
	mutex_unlock(&master->lock);

	return 0;
}

static ssize_t external_mode_show(struct device *dev,
				  struct device_attribute *attr, char *buf)
{
	struct fsi_master_acf *master = dev_get_drvdata(dev);

	return snprintf(buf, PAGE_SIZE - 1, "%u\n",
			master->external_mode ? 1 : 0);
}

static ssize_t external_mode_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t count)
{
	struct fsi_master_acf *master = dev_get_drvdata(dev);
	unsigned long val;
	bool external_mode;
	int err;

	err = kstrtoul(buf, 0, &val);
	if (err)
		return err;

	external_mode = !!val;

	mutex_lock(&master->lock);

	if (external_mode == master->external_mode) {
		mutex_unlock(&master->lock);
		return count;
	}

	master->external_mode = external_mode;
	if (master->external_mode) {
		fsi_master_acf_terminate(master);
		fsi_master_acf_setup_external(master);
	} else
		fsi_master_acf_setup(master);

	mutex_unlock(&master->lock);

	fsi_master_rescan(&master->master);

	return count;
}

static DEVICE_ATTR(external_mode, 0664,
		external_mode_show, external_mode_store);

static int fsi_master_acf_gpio_request(void *data)
{
	struct fsi_master_acf *master = data;
	int timeout;
	u8 val;

	/* Note: This doesn't require holding out mutex */

	/* Write request */
	iowrite8(ARB_ARM_REQ, master->sram + ARB_REG);

	/*
	 * There is a race (which does happen at boot time) when we get an
	 * arbitration request as we are either about to or just starting
	 * the coprocessor.
	 *
	 * To handle it, we first check if we are running. If not yet we
	 * check whether the copro is started in the SCU.
	 *
	 * If it's not started, we can basically just assume we have arbitration
	 * and return. Otherwise, we wait normally expecting for the arbitration
	 * to eventually complete.
	 */
	if (ioread32(master->sram + CF_STARTED) == 0) {
		unsigned int reg = 0;

		regmap_read(master->scu, SCU_COPRO_CTRL, &reg);
		if (!(reg & SCU_COPRO_CLK_EN))
			return 0;
	}

	/* Ring doorbell if any */
	if (master->cvic)
		iowrite32(0x2, master->cvic + CVIC_TRIG_REG);

	for (timeout = 0; timeout < 10000; timeout++) {
		val = ioread8(master->sram + ARB_REG);
		if (val != ARB_ARM_REQ)
			break;
		udelay(1);
	}

	/* If it failed, override anyway */
	if (val != ARB_ARM_ACK)
		dev_warn(master->dev, "GPIO request arbitration timeout\n");

	return 0;
}

static int fsi_master_acf_gpio_release(void *data)
{
	struct fsi_master_acf *master = data;

	/* Write release */
	iowrite8(0, master->sram + ARB_REG);

	/* Ring doorbell if any */
	if (master->cvic)
		iowrite32(0x2, master->cvic + CVIC_TRIG_REG);

	return 0;
}

static void fsi_master_acf_release(struct device *dev)
{
	struct fsi_master_acf *master = to_fsi_master_acf(to_fsi_master(dev));

	/* Cleanup, stop coprocessor */
	mutex_lock(&master->lock);
	fsi_master_acf_terminate(master);
	aspeed_gpio_copro_set_ops(NULL, NULL);
	mutex_unlock(&master->lock);

	/* Free resources */
	gen_pool_free(master->sram_pool, (unsigned long)master->sram, SRAM_SIZE);
	of_node_put(dev_of_node(master->dev));

	kfree(master);
}

static const struct aspeed_gpio_copro_ops fsi_master_acf_gpio_ops = {
	.request_access = fsi_master_acf_gpio_request,
	.release_access = fsi_master_acf_gpio_release,
};

static int fsi_master_acf_probe(struct platform_device *pdev)
{
	struct device_node *np, *mnode = dev_of_node(&pdev->dev);
	struct genpool_data_fixed gpdf;
	struct fsi_master_acf *master;
	struct gpio_desc *gpio;
	struct resource res;
	uint32_t cf_mem_align;
	int rc;

	master = kzalloc(sizeof(*master), GFP_KERNEL);
	if (!master)
		return -ENOMEM;

	master->dev = &pdev->dev;
	master->master.dev.parent = master->dev;
	master->last_addr = LAST_ADDR_INVALID;

	/* AST2400 vs. AST2500 */
	master->is_ast2500 = of_device_is_compatible(mnode, "aspeed,ast2500-cf-fsi-master");

	/* Grab the SCU, we'll need to access it to configure the coprocessor */
	if (master->is_ast2500)
		master->scu = syscon_regmap_lookup_by_compatible("aspeed,ast2500-scu");
	else
		master->scu = syscon_regmap_lookup_by_compatible("aspeed,ast2400-scu");
	if (IS_ERR(master->scu)) {
		dev_err(&pdev->dev, "failed to find SCU regmap\n");
		rc = PTR_ERR(master->scu);
		goto err_free;
	}

	/* Grab all the GPIOs we need */
	gpio = devm_gpiod_get(&pdev->dev, "clock", 0);
	if (IS_ERR(gpio)) {
		dev_err(&pdev->dev, "failed to get clock gpio\n");
		rc = PTR_ERR(gpio);
		goto err_free;
	}
	master->gpio_clk = gpio;

	gpio = devm_gpiod_get(&pdev->dev, "data", 0);
	if (IS_ERR(gpio)) {
		dev_err(&pdev->dev, "failed to get data gpio\n");
		rc = PTR_ERR(gpio);
		goto err_free;
	}
	master->gpio_data = gpio;

	/* Optional GPIOs */
	gpio = devm_gpiod_get_optional(&pdev->dev, "trans", 0);
	if (IS_ERR(gpio)) {
		dev_err(&pdev->dev, "failed to get trans gpio\n");
		rc = PTR_ERR(gpio);
		goto err_free;
	}
	master->gpio_trans = gpio;

	gpio = devm_gpiod_get_optional(&pdev->dev, "enable", 0);
	if (IS_ERR(gpio)) {
		dev_err(&pdev->dev, "failed to get enable gpio\n");
		rc = PTR_ERR(gpio);
		goto err_free;
	}
	master->gpio_enable = gpio;

	gpio = devm_gpiod_get_optional(&pdev->dev, "mux", 0);
	if (IS_ERR(gpio)) {
		dev_err(&pdev->dev, "failed to get mux gpio\n");
		rc = PTR_ERR(gpio);
		goto err_free;
	}
	master->gpio_mux = gpio;

	/* Grab the reserved memory region (use DMA API instead ?) */
	np = of_parse_phandle(mnode, "memory-region", 0);
	if (!np) {
		dev_err(&pdev->dev, "Didn't find reserved memory\n");
		rc = -EINVAL;
		goto err_free;
	}
	rc = of_address_to_resource(np, 0, &res);
	of_node_put(np);
	if (rc) {
		dev_err(&pdev->dev, "Couldn't address to resource for reserved memory\n");
		rc = -ENOMEM;
		goto err_free;
	}
	master->cf_mem_size = resource_size(&res);
	master->cf_mem_addr = (uint32_t)res.start;
	cf_mem_align = master->is_ast2500 ? 0x00100000 : 0x00200000;
	if (master->cf_mem_addr & (cf_mem_align - 1)) {
		dev_err(&pdev->dev, "Reserved memory has insufficient alignment\n");
		rc = -ENOMEM;
		goto err_free;
	}
	master->cf_mem = devm_ioremap_resource(&pdev->dev, &res);
 	if (IS_ERR(master->cf_mem)) {
		rc = PTR_ERR(master->cf_mem);
 		goto err_free;
	}
	dev_dbg(&pdev->dev, "DRAM allocation @%x\n", master->cf_mem_addr);

	/* AST2500 has a SW interrupt to the coprocessor */
	if (master->is_ast2500) {
		/* Grab the CVIC (ColdFire interrupts controller) */
		np = of_parse_phandle(mnode, "aspeed,cvic", 0);
		if (!np) {
			dev_err(&pdev->dev, "Didn't find CVIC\n");
			rc = -EINVAL;
			goto err_free;
		}
		master->cvic = devm_of_iomap(&pdev->dev, np, 0, NULL);
		if (IS_ERR(master->cvic)) {
			of_node_put(np);
			rc = PTR_ERR(master->cvic);
			dev_err(&pdev->dev, "Error %d mapping CVIC\n", rc);
			goto err_free;
		}
		rc = of_property_read_u32(np, "copro-sw-interrupts",
					  &master->cvic_sw_irq);
		of_node_put(np);
		if (rc) {
			dev_err(&pdev->dev, "Can't find coprocessor SW interrupt\n");
			goto err_free;
		}
	}

	/* Grab the SRAM */
	master->sram_pool = of_gen_pool_get(dev_of_node(&pdev->dev), "aspeed,sram", 0);
	if (!master->sram_pool) {
		rc = -ENODEV;
		dev_err(&pdev->dev, "Can't find sram pool\n");
		goto err_free;
	}

	/* Current microcode only deals with fixed location in SRAM */
	gpdf.offset = 0;
	master->sram = (void __iomem *)gen_pool_alloc_algo(master->sram_pool, SRAM_SIZE,
							   gen_pool_fixed_alloc, &gpdf);
	if (!master->sram) {
		rc = -ENOMEM;
		dev_err(&pdev->dev, "Failed to allocate sram from pool\n");
		goto err_free;
	}
	dev_dbg(&pdev->dev, "SRAM allocation @%lx\n",
		(unsigned long)gen_pool_virt_to_phys(master->sram_pool,
						     (unsigned long)master->sram));

	/*
	 * Hookup with the GPIO driver for arbitration of GPIO banks
	 * ownership.
	 */
	aspeed_gpio_copro_set_ops(&fsi_master_acf_gpio_ops, master);

	/* Default FSI command delays */
	master->t_send_delay = FSI_SEND_DELAY_CLOCKS;
	master->t_echo_delay = FSI_ECHO_DELAY_CLOCKS;
	master->master.n_links = 1;
	if (master->is_ast2500)
		master->master.flags = FSI_MASTER_FLAG_SWCLOCK;
	master->master.read = fsi_master_acf_read;
	master->master.write = fsi_master_acf_write;
	master->master.term = fsi_master_acf_term;
	master->master.send_break = fsi_master_acf_break;
	master->master.link_enable = fsi_master_acf_link_enable;
	master->master.link_config = fsi_master_acf_link_config;
	master->master.dev.of_node = of_node_get(dev_of_node(master->dev));
	master->master.dev.release = fsi_master_acf_release;
	platform_set_drvdata(pdev, master);
	mutex_init(&master->lock);

	mutex_lock(&master->lock);
	rc = fsi_master_acf_setup(master);
	mutex_unlock(&master->lock);
	if (rc)
		goto release_of_dev;

	rc = device_create_file(&pdev->dev, &dev_attr_external_mode);
	if (rc)
		goto stop_copro;

	rc = fsi_master_register(&master->master);
	if (!rc)
		return 0;

	device_remove_file(master->dev, &dev_attr_external_mode);
	put_device(&master->master.dev);
	return rc;

 stop_copro:
	fsi_master_acf_terminate(master);
 release_of_dev:
	aspeed_gpio_copro_set_ops(NULL, NULL);
	gen_pool_free(master->sram_pool, (unsigned long)master->sram, SRAM_SIZE);
	of_node_put(dev_of_node(master->dev));
 err_free:
	kfree(master);
	return rc;
}


static void fsi_master_acf_remove(struct platform_device *pdev)
{
	struct fsi_master_acf *master = platform_get_drvdata(pdev);

	device_remove_file(master->dev, &dev_attr_external_mode);

	fsi_master_unregister(&master->master);
}

static const struct of_device_id fsi_master_acf_match[] = {
	{ .compatible = "aspeed,ast2400-cf-fsi-master" },
	{ .compatible = "aspeed,ast2500-cf-fsi-master" },
	{ },
};
MODULE_DEVICE_TABLE(of, fsi_master_acf_match);

static struct platform_driver fsi_master_acf = {
	.driver = {
		.name		= "fsi-master-acf",
		.of_match_table	= fsi_master_acf_match,
	},
	.probe	= fsi_master_acf_probe,
	.remove = fsi_master_acf_remove,
};

module_platform_driver(fsi_master_acf);
MODULE_DESCRIPTION("A FSI master based on Aspeed ColdFire coprocessor");
MODULE_LICENSE("GPL");
MODULE_FIRMWARE(FW_FILE_NAME);