/*
 * This file is part of the flashrom project.
 *
 * Copyright (C) 2008 Wang Qingpei <Qingpei.Wang@amd.com>
 * Copyright (C) 2008 Joe Bao <Zheng.Bao@amd.com>
 * Copyright (C) 2008 Advanced Micro Devices, Inc.
 * Copyright (C) 2009, 2010 Carl-Daniel Hailfinger
 *
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#if defined(__i386__) || defined(__x86_64__)

#include <string.h>
#include <stdlib.h>
#include "flash.h"
#include "programmer.h"
#include "hwaccess.h"
#include "spi.h"

/* This struct is unused, but helps visualize the SB600 SPI BAR layout.
 *struct sb600_spi_controller {
 *	unsigned int spi_cntrl0;	/ * 00h * /
 *	unsigned int restrictedcmd1;	/ * 04h * /
 *	unsigned int restrictedcmd2;	/ * 08h * /
 *	unsigned int spi_cntrl1;	/ * 0ch * /
 *	unsigned int spi_cmdvalue0;	/ * 10h * /
 *	unsigned int spi_cmdvalue1;	/ * 14h * /
 *	unsigned int spi_cmdvalue2;	/ * 18h * /
 *	unsigned int spi_fakeid;	/ * 1Ch * /
 *};
 */

static uint8_t *sb600_spibar = NULL;

static void reset_internal_fifo_pointer(void)
{
	mmio_writeb(mmio_readb(sb600_spibar + 2) | 0x10, sb600_spibar + 2);

	/* FIXME: This loop needs a timeout and a clearer message. */
	while (mmio_readb(sb600_spibar + 0xD) & 0x7)
		msg_pspew("reset\n");
}

static int compare_internal_fifo_pointer(uint8_t want)
{
	uint8_t tmp;

	tmp = mmio_readb(sb600_spibar + 0xd) & 0x07;
	want &= 0x7;
	if (want != tmp) {
		msg_perr("FIFO pointer corruption! Pointer is %d, wanted %d\n", tmp, want);
		msg_perr("Something else is accessing the flash chip and "
			 "causes random corruption.\nPlease stop all "
			 "applications and drivers and IPMI which access the "
			 "flash chip.\n");
		return 1;
	} else {
		msg_pspew("SB600 FIFO pointer is %d, wanted %d\n", tmp, want);
		return 0;
	}
}

static int reset_compare_internal_fifo_pointer(uint8_t want)
{
	int ret;

	ret = compare_internal_fifo_pointer(want);
	reset_internal_fifo_pointer();
	return ret;
}

static void execute_command(void)
{
	mmio_writeb(mmio_readb(sb600_spibar + 2) | 1, sb600_spibar + 2);

	while (mmio_readb(sb600_spibar + 2) & 1)
		;
}

static int sb600_spi_send_command(struct flashctx *flash, unsigned int writecnt,
				  unsigned int readcnt,
				  const unsigned char *writearr,
				  unsigned char *readarr)
{
	int count;
	/* First byte is cmd which can not being sent through FIFO. */
	unsigned char cmd = *writearr++;
	unsigned int readoffby1;
	unsigned char readwrite;

	writecnt--;

	msg_pspew("%s, cmd=%x, writecnt=%x, readcnt=%x\n",
		  __func__, cmd, writecnt, readcnt);

	if (readcnt > 8) {
		msg_pinfo("%s, SB600 SPI controller can not receive %d bytes, "
		       "it is limited to 8 bytes\n", __func__, readcnt);
		return SPI_INVALID_LENGTH;
	}

	if (writecnt > 8) {
		msg_pinfo("%s, SB600 SPI controller can not send %d bytes, "
		       "it is limited to 8 bytes\n", __func__, writecnt);
		return SPI_INVALID_LENGTH;
	}

	/* This is a workaround for a bug in SB600 and SB700. If we only send
	 * an opcode and no additional data/address, the SPI controller will
	 * read one byte too few from the chip. Basically, the last byte of
	 * the chip response is discarded and will not end up in the FIFO.
	 * It is unclear if the CS# line is set high too early as well.
	 */
	readoffby1 = (writecnt) ? 0 : 1;
	readwrite = (readcnt + readoffby1) << 4 | (writecnt);
	mmio_writeb(readwrite, sb600_spibar + 1);
	mmio_writeb(cmd, sb600_spibar + 0);

	/* Before we use the FIFO, reset it first. */
	reset_internal_fifo_pointer();

	/* Send the write byte to FIFO. */
	msg_pspew("Writing: ");
	for (count = 0; count < writecnt; count++, writearr++) {
		msg_pspew("[%02x]", *writearr);
		mmio_writeb(*writearr, sb600_spibar + 0xC);
	}
	msg_pspew("\n");

	/*
	 * We should send the data by sequence, which means we need to reset
	 * the FIFO pointer to the first byte we want to send.
	 */
	if (reset_compare_internal_fifo_pointer(writecnt))
		return SPI_PROGRAMMER_ERROR;

	msg_pspew("Executing: \n");
	execute_command();

	/*
	 * After the command executed, we should find out the index of the
	 * received byte. Here we just reset the FIFO pointer and skip the
	 * writecnt.
	 * It would be possible to increase the FIFO pointer by one instead
	 * of reading and discarding one byte from the FIFO.
	 * The FIFO is implemented on top of an 8 byte ring buffer and the
	 * buffer is never cleared. For every byte that is shifted out after
	 * the opcode, the FIFO already stores the response from the chip.
	 * Usually, the chip will respond with 0x00 or 0xff.
	 */
	if (reset_compare_internal_fifo_pointer(writecnt + readcnt))
		return SPI_PROGRAMMER_ERROR;

	/* Skip the bytes we sent. */
	msg_pspew("Skipping: ");
	for (count = 0; count < writecnt; count++) {
		cmd = mmio_readb(sb600_spibar + 0xC);
		msg_pspew("[%02x]", cmd);
	}
	msg_pspew("\n");
	if (compare_internal_fifo_pointer(writecnt))
		return SPI_PROGRAMMER_ERROR;

	msg_pspew("Reading: ");
	for (count = 0; count < readcnt; count++, readarr++) {
		*readarr = mmio_readb(sb600_spibar + 0xC);
		msg_pspew("[%02x]", *readarr);
	}
	msg_pspew("\n");
	if (reset_compare_internal_fifo_pointer(readcnt + writecnt))
		return SPI_PROGRAMMER_ERROR;

	if (mmio_readb(sb600_spibar + 1) != readwrite) {
		msg_perr("Unexpected change in SB600 read/write count!\n");
		msg_perr("Something else is accessing the flash chip and "
			 "causes random corruption.\nPlease stop all "
			 "applications and drivers and IPMI which access the "
			 "flash chip.\n");
		return SPI_PROGRAMMER_ERROR;
	}

	return 0;
}

static int sb600_handle_imc(struct pci_dev *dev, bool amd_imc_force)
{
	/* Handle IMC everywhere but sb600 which does not have one. */
	if (dev->device_id == 0x438d)
		return 0;

	/* TODO: we should not only look at IntegratedImcPresent (LPC Dev 20, Func 3, 40h) but also at
	 * IMCEnable(Strap) and Override EcEnable(Strap) (sb8xx, sb9xx?, a50: Misc_Reg: 80h-87h;
	 * sb7xx, sp5100: PM_Reg: B0h-B1h) etc. */
	uint8_t reg = pci_read_byte(dev, 0x40);
	if ((reg & (1 << 7)) == 0) {
		msg_pdbg("IMC is not active.\n");
		return 0;
	}

	if (!amd_imc_force)
		programmer_may_write = 0;
	msg_pinfo("Writes have been disabled for safety reasons because the IMC is active\n"
		  "and it could interfere with accessing flash memory. Flashrom will try\n"
		  "to disable it temporarily but even then this might not be safe:\n"
		  "when it is reenabled and after a reboot it expects to find working code\n"
		  "in the flash and it is unpredictable what happens if there is none.\n"
		  "\n"
		  "To be safe make sure that there is a working IMC firmware at the right\n"
		  "location in the image you intend to write and do not attempt to erase.\n"
		  "\n"
		  "You can enforce write support with the amd_imc_force programmer option.\n");
	if (amd_imc_force)
		msg_pinfo("Continuing with write support because the user forced us to!\n");

	return amd_imc_shutdown(dev);
}

static const struct spi_programmer spi_programmer_sb600 = {
	.type = SPI_CONTROLLER_SB600,
	.max_data_read = 8,
	.max_data_write = 5,
	.command = sb600_spi_send_command,
	.multicommand = default_spi_send_multicommand,
	.read = default_spi_read,
	.write_256 = default_spi_write_256,
	.write_aai = default_spi_write_aai,
};

int sb600_probe_spi(struct pci_dev *dev)
{
	struct pci_dev *smbus_dev;
	uint32_t tmp;
	uint8_t reg;
	bool amd_imc_force = false;
	static const char *const speed_names[4] = {
		"66/reserved", "33", "22", "16.5"
	};

	char *arg = extract_programmer_param("amd_imc_force");
	if (arg && !strcmp(arg, "yes")) {
		amd_imc_force = true;
		msg_pspew("amd_imc_force enabled.\n");
	} else if (arg && !strlen(arg)) {
		msg_perr("Missing argument for amd_imc_force.\n");
		free(arg);
		return ERROR_FATAL;
	} else if (arg) {
		msg_perr("Unknown argument for amd_imc_force: \"%s\" (not \"yes\").\n", arg);
		free(arg);
		return ERROR_FATAL;
	}
	free(arg);

	/* Read SPI_BaseAddr */
	tmp = pci_read_long(dev, 0xa0);
	tmp &= 0xffffffe0;	/* remove bits 4-0 (reserved) */
	msg_pdbg("SPI base address is at 0x%x\n", tmp);

	/* If the BAR has address 0, it is unlikely SPI is used. */
	if (!tmp)
		return 0;

	/* Physical memory has to be mapped at page (4k) boundaries. */
	sb600_spibar = physmap("SB600 SPI registers", tmp & 0xfffff000,
			       0x1000);
	/* The low bits of the SPI base address are used as offset into
	 * the mapped page.
	 */
	sb600_spibar += tmp & 0xfff;

	tmp = pci_read_long(dev, 0xa0);
	msg_pdbg("AltSpiCSEnable=%i, SpiRomEnable=%i, "
		     "AbortEnable=%i\n", tmp & 0x1, (tmp & 0x2) >> 1,
		     (tmp & 0x4) >> 2);
	tmp = (pci_read_byte(dev, 0xba) & 0x4) >> 2;
	msg_pdbg("PrefetchEnSPIFromIMC=%i, ", tmp);

	tmp = pci_read_byte(dev, 0xbb);
	/* FIXME: Set bit 3,6,7 if not already set.
	 * Set bit 5, otherwise SPI accesses are pointless in LPC mode.
	 * See doc 42413 AMD SB700/710/750 RPR.
	 */
	msg_pdbg("PrefetchEnSPIFromHost=%i, SpiOpEnInLpcMode=%i\n",
		     tmp & 0x1, (tmp & 0x20) >> 5);
	tmp = mmio_readl(sb600_spibar);
	/* FIXME: If SpiAccessMacRomEn or SpiHostAccessRomEn are zero on
	 * SB700 or later, reads and writes will be corrupted. Abort in this
	 * case. Make sure to avoid this check on SB600.
	 */
	msg_pdbg("(0x%08" PRIx32 ") fastReadEnable=%u, SpiArbEnable=%i, SpiAccessMacRomEn=%i, "
		     "SpiHostAccessRomEn=%i, ArbWaitCount=%i, "
		     "SpiBridgeDisable=%i, DropOneClkOnRd=%i\n",
		     tmp, (tmp >> 18) & 0x1,
		     (tmp >> 19) & 0x1, (tmp >> 22) & 0x1,
		     (tmp >> 23) & 0x1, (tmp >> 24) & 0x7,
		     (tmp >> 27) & 0x1, (tmp >> 28) & 0x1);
	tmp = (mmio_readb(sb600_spibar + 0xd) >> 4) & 0x3;
	msg_pdbg("NormSpeed is %s MHz\n", speed_names[tmp]);

	/* Look for the SMBus device. */
	smbus_dev = pci_dev_find(0x1002, 0x4385);

	if (!smbus_dev) {
		smbus_dev = pci_dev_find(0x1022, 0x780b); /* AMD Hudson */
		if (!smbus_dev) {
			msg_perr("ERROR: SMBus device not found. Not enabling SPI.\n");
			return ERROR_NONFATAL;
		}
	}

	/* Note about the bit tests below: If a bit is zero, the GPIO is SPI. */
	/* GPIO11/SPI_DO and GPIO12/SPI_DI status */
	reg = pci_read_byte(smbus_dev, 0xAB);
	reg &= 0xC0;
	msg_pdbg("GPIO11 used for %s\n", (reg & (1 << 6)) ? "GPIO" : "SPI_DO");
	msg_pdbg("GPIO12 used for %s\n", (reg & (1 << 7)) ? "GPIO" : "SPI_DI");
	if (reg != 0x00) {
		msg_pdbg("Not enabling SPI");
		return 0;
	}
	/* GPIO31/SPI_HOLD and GPIO32/SPI_CS status */
	reg = pci_read_byte(smbus_dev, 0x83);
	reg &= 0xC0;
	msg_pdbg("GPIO31 used for %s\n", (reg & (1 << 6)) ? "GPIO" : "SPI_HOLD");
	msg_pdbg("GPIO32 used for %s\n", (reg & (1 << 7)) ? "GPIO" : "SPI_CS");
	/* SPI_HOLD is not used on all boards, filter it out. */
	if ((reg & 0x80) != 0x00) {
		msg_pdbg("Not enabling SPI");
		return 0;
	}
	/* GPIO47/SPI_CLK status */
	reg = pci_read_byte(smbus_dev, 0xA7);
	reg &= 0x40;
	msg_pdbg("GPIO47 used for %s\n", (reg & (1 << 6)) ? "GPIO" : "SPI_CLK");
	if (reg != 0x00) {
		msg_pdbg("Not enabling SPI");
		return 0;
	}

	if (sb600_handle_imc(dev, amd_imc_force) != 0)
		return ERROR_FATAL;

	/* Bring the FIFO to a clean state. */
	reset_internal_fifo_pointer();

	register_spi_programmer(&spi_programmer_sb600);
	return 0;
}

#endif