oaf-boost/libn3ds/source/drivers/mmc/sdmmc.c

/*
 *   This file is part of libn3ds
 *   Copyright (C) 2024 derrek, profi200
 *
 *   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 3 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 <string.h>
#include "drivers/mmc/sdmmc.h" // Includes types.h.
#include "drivers/tmio.h"
#include "drivers/tmio_config.h"
#ifdef __ARM9__
#include "arm9/drivers/timer.h"
#elif __ARM11__
#include "arm11/drivers/timer.h"
#endif // #ifdef __ARM9__
#include "drivers/mmc/mmc_spec.h"
#include "drivers/mmc/sd_spec.h"


// Note on INIT_CLOCK:
// 400 kHz is allowed by the specs. 523 kHz has been proven to work reliably
// for SD cards and eMMC but very early MMCs can fail at init.
// We lose about 5 ms of time on init by using 261 kHz.
#define INIT_CLOCK     (400000u)   // Maximum 400 kHz.
#define DEFAULT_CLOCK  (20000000u) // Maximum 20 MHz.
#define HS_CLOCK       (50000000u) // Maximum 50 MHz.


#define MMC_OCR_VOLT_MASK  (MMC_OCR_3_2_3_3V)                        // We support 3.3V only.
#define SD_OCR_VOLT_MASK   (SD_OCR_3_2_3_3V)                         // We support 3.3V only.
#define SD_IF_COND_ARG     (SD_CMD8_VHS_2_7_3_6V | SD_CMD8_CHK_PATT)
#define SD_OP_COND_ARG     (SD_ACMD41_XPC | SD_OCR_VOLT_MASK)        // We support 150 mA and 3.3V. Without HCS bit.
#define MMC_OP_COND_ARG    (MMC_OCR_SECT_MODE | MMC_OCR_VOLT_MASK)   // We support sector addressing and 3.3V.

// Note: DEV_TYPE_NONE must be zero.
enum
{
	// Device types.
	DEV_TYPE_NONE  = 0u, // Unitialized/no device.
	DEV_TYPE_MMC   = 1u, // (e)MMC.
	DEV_TYPE_MMCHC = 2u, // High capacity (e)MMC (>2 GB).
	DEV_TYPE_SDSC  = 3u, // SDSC.
	DEV_TYPE_SDHC  = 4u, // SDHC, SDXC.
	DEV_TYPE_SDUC  = 5u  // SDUC.
};

#define IS_DEV_MMC(dev)  ((dev) < DEV_TYPE_SDSC)


typedef struct
{
	TmioPort port;
	u8 type;       // Device type. 0 = none, 1 = (e)MMC, 2 = High capacity (e)MMC,
	               // 3 = SDSC, 4 = SDHC/SDXC, 5 = SDUC.
	u8 prot;       // Protection bits. Each bit 1 = protected.
	               // Bit 0 SD card slider, bit 1 temporary write protection (CSD),
	               // bit 2 permanent write protection (CSD) and bit 3 password protection.
	u16 rca;       // Relative Card Address (RCA).
	u16 ccc;       // (e)MMC/SD command class support from CSD. One per bit starting at 0.
	u32 sectors;   // Size in 512 byte units.
	u32 status;    // R1 card status on error. Only updated on errors.

	// Cached card infos.
	u32 cid[4];    // Raw CID without the CRC.
} SdmmcDev;

static SdmmcDev g_devs[2] = {0};



static u32 sendAppCmd(TmioPort *const port, const u16 cmd, const u32 arg, const u32 rca)
{
	// Send app CMD. Same CMD for (e)MMC/SD.
	// TODO: Check the APP_CMD bit in the response?
	//       Linux does it but is it really necessary? SD spec 4.3.9.1.
	u32 res = TMIO_sendCommand(port, MMC_APP_CMD, rca);
	if(res == 0)
	{
		res = TMIO_sendCommand(port, cmd, arg);
	}

	return res;
}

static u32 goIdleState(TmioPort *const port)
{
	// Enter idle state before we start the init procedure.
	// Works from all but inactive state. CMD is the same for (e)MMC/SD.
	// For (e)MMC there are optional init paths:
	// arg = 0x00000000 -> GO_IDLE_STATE.
	// arg = 0xF0F0F0F0 -> GO_PRE_IDLE_STATE.
	// arg = 0xFFFFFFFA -> BOOT_INITIATION.
	u32 res = TMIO_sendCommand(port, MMC_GO_IDLE_STATE, 0);
	if(res != 0) return SDMMC_ERR_GO_IDLE_STATE;

	return SDMMC_ERR_NONE;
}

static u32 initIdleState(TmioPort *const port, u8 *const devTypeOut)
{
	// Tell the card what interfaces and voltages we support.
	// Only SD v2 and up will respond. (e)MMC won't respond.
	u32 res = TMIO_sendCommand(port, SD_SEND_IF_COND, SD_IF_COND_ARG);
	if(res == 0)
	{
		// If the card supports the interfaces and voltages
		// it should echo back the check pattern and set the
		// support bits.
		// Since we don't support anything but the
		// standard SD interface at 3.3V we can check
		// the whole response at once.
		if(port->resp[0] != SD_IF_COND_ARG) return SDMMC_ERR_IF_COND_RESP;
	}
	else if(res != STATUS_ERR_CMD_TIMEOUT) return SDMMC_ERR_SEND_IF_COND; // Card responded but an error occured.

	// Send the first app CMD. If this times out it's (e)MMC.
	// If SEND_IF_COND timed out tell the SD card we are a v1 host.
	const u32 opCondArg = SD_OP_COND_ARG | (res<<8 ^ SD_ACMD41_HCS); // Caution! Controller specific hack.
	u8 devType = DEV_TYPE_SDSC;
	res = sendAppCmd(port, SD_APP_SD_SEND_OP_COND, opCondArg, 0);
	if(res == STATUS_ERR_CMD_TIMEOUT) devType = DEV_TYPE_MMC;        // Continue with (e)MMC init.
	else if(res != 0)                 return SDMMC_ERR_SEND_OP_COND; // Unknown error.

	if(devType == DEV_TYPE_MMC) // (e)MMC.
	{
		// Loop until a timeout of 1 second or the card is ready.
		u32 tries = 200;
		u32 ocr;
		while(1)
		{
			res = TMIO_sendCommand(port, MMC_SEND_OP_COND, MMC_OP_COND_ARG);
			if(res != 0) return SDMMC_ERR_SEND_OP_COND;

			ocr = port->resp[0];
			if(!--tries || (ocr & MMC_OCR_READY)) break;

			// Linux uses 10 ms but the card doesn't become ready faster
			// when polling with delay. Use 5 ms as compromise so not much
			// time is wasted when the card becomes ready in the middle of the delay.
			TIMER_sleepMs(5);
		}

		// (e)MMC didn't finish init within 1 second.
		if(tries == 0) return SDMMC_ERR_OP_COND_TMOUT;

		// Check if the (e)MMC supports the voltage and if it's high capacity.
		if(!(ocr & MMC_OCR_VOLT_MASK)) return SDMMC_ERR_VOLT_SUPPORT; // Voltage not supported.
		if(ocr & MMC_OCR_SECT_MODE)    devType = DEV_TYPE_MMCHC;      // 7.4.3.
	}
	else // SD card.
	{
		// Loop until a timeout of 1 second or the card is ready.
		u32 tries = 200;
		u32 ocr;
		while(1)
		{
			ocr = port->resp[0];
			if(!--tries || (ocr & SD_OCR_READY)) break;

			// Linux uses 10 ms but the card doesn't become ready faster
			// when polling with delay. Use 5 ms as compromise so not much
			// time is wasted when the card becomes ready in the middle of the delay.
			TIMER_sleepMs(5);

			res = sendAppCmd(port, SD_APP_SD_SEND_OP_COND, opCondArg, 0);
			if(res != 0) return SDMMC_ERR_SEND_OP_COND;
		}

		// SD card didn't finish init within 1 second.
		if(tries == 0) return SDMMC_ERR_OP_COND_TMOUT;

		if(!(ocr & SD_OCR_VOLT_MASK)) return SDMMC_ERR_VOLT_SUPPORT; // Voltage not supported.
		if(ocr & SD_OCR_CCS)          devType = DEV_TYPE_SDHC;
	}

	*devTypeOut = devType;

	return SDMMC_ERR_NONE;
}

static u32 initReadyState(SdmmcDev *const dev)
{
	TmioPort *const port = &dev->port;

	// SD card voltage switch sequence goes here if supported.

	// Get the CID. CMD is the same for (e)MMC/SD.
	u32 res = TMIO_sendCommand(port, MMC_ALL_SEND_CID, 0);
	if(res != 0) return SDMMC_ERR_ALL_SEND_CID;
	memcpy(dev->cid, port->resp, 16);

	return SDMMC_ERR_NONE;
}

static u32 initIdentState(SdmmcDev *const dev, const u8 devType, u32 *const rcaOut)
{
	TmioPort *const port = &dev->port;

	u32 rca;
	if(IS_DEV_MMC(devType)) // (e)MMC.
	{
		// Set the RCA of the (e)MMC to 1. 0 is reserved.
		// The RCA is in the upper 16 bits of the argument.
		rca = 1;
		u32 res = TMIO_sendCommand(port, MMC_SET_RELATIVE_ADDR, rca<<16);
		if(res != 0) return SDMMC_ERR_SET_SEND_RCA;
	}
	else // SD card.
	{
		// Ask the SD card to send its RCA.
		u32 res = TMIO_sendCommand(port, SD_SEND_RELATIVE_ADDR, 0);
		if(res != 0) return SDMMC_ERR_SET_SEND_RCA;

		// RCA in upper 16 bits. Discards lower status bits of R6 response.
		rca = port->resp[0]>>16;
	}

	dev->rca = rca;
	*rcaOut = rca<<16;

	return SDMMC_ERR_NONE;
}

// Based on UNSTUFF_BITS from linux/drivers/mmc/core/sd.c.
// Extracts up to 32 bits from a u32[4] array.
static inline u32 extractBits(const u32 resp[4], const u32 start, const u32 size)
{
	const u32 mask = (size < 32 ? BIT(size) : 0u) - 1;
	const u32 off = 3 - (start / 32);
	const u32 shift = start & 31u;

	u32 res = resp[off]>>shift;
	if(size + shift > 32)
		res |= resp[off - 1]<<((32u - shift) & 31u);

	return res & mask;
}

static void parseCsd(SdmmcDev *const dev, const u8 devType, u8 *const spec_vers_out)
{
	// Note: The MSBs are in csd[0].
	const u32 *const csd = dev->port.resp;

	const u8 structure = extractBits(csd, 126, 2); // [127:126]
	*spec_vers_out = extractBits(csd, 122, 4);     // [125:122] All 0 for SD cards.
	dev->ccc = extractBits(csd, 84, 12);           // [95:84]
	u32 sectors = 0;
	if(structure == 0 || devType == DEV_TYPE_MMC) // structure = 0 is CSD version 1.0.
	{
		const u32 read_bl_len = extractBits(csd, 80, 4);  // [83:80]
		const u32 c_size      = extractBits(csd, 62, 12); // [73:62]
		const u32 c_size_mult = extractBits(csd, 47, 3);  // [49:47]

		// For SD cards with CSD 1.0 and <=2 GB (e)MMC this calculation is used.
		// Note: READ_BL_LEN is at least 9.
		// Modified/simplified to calculate sectors instead of bytes.
		sectors = (c_size + 1)<<(c_size_mult + 2 + read_bl_len - 9);
	}
	else if(devType != DEV_TYPE_MMCHC)
	{
		// SD CSD version 3.0 format.
		// For version 2.0 this is 22 bits however the upper bits
		// are reserved and zero filled so this is fine.
		const u32 c_size = extractBits(csd, 48, 28); // [75:48]

		// Calculation for SD cards with CSD >1.0.
		sectors = (c_size + 1)<<10;
	}
	// Else for high capacity (e)MMC the sectors will be read later from EXT_CSD.
	dev->sectors = sectors;

	// Parse temporary and permanent write protection bits.
	u8 prot = extractBits(csd, 12, 1)<<1; // [12:12] Not checked by Linux.
	prot |= extractBits(csd, 13, 1)<<2;   // [13:13]
	dev->prot |= prot;
}

static u32 initStandbyState(SdmmcDev *const dev, const u8 devType, const u32 rca, u8 *const spec_vers_out)
{
	TmioPort *const port = &dev->port;

	// Get the CSD. CMD is the same for (e)MMC/SD.
	u32 res = TMIO_sendCommand(port, MMC_SEND_CSD, rca);
	if(res != 0) return SDMMC_ERR_SEND_CSD;
	parseCsd(dev, devType, spec_vers_out);

	// CMD is the same for (e)MMC/SD however both R1 and R1b responses are used.
	// We assume R1b and hope it doesn't time out.
	res = TMIO_sendCommand(port, MMC_SELECT_CARD, rca);
	if(res != 0) return SDMMC_ERR_SELECT_CARD;

	// The SD card spec mentions that we should check the lock bit in the
	// response to CMD7 to identify cards requiring a password to unlock.
	// Same seems to apply for (e)MMC.
	// Same bit for (e)MMC/SD R1 card status.
	dev->prot |= (port->resp[0] & MMC_R1_CARD_IS_LOCKED)>>22; // Bit 3.

	return SDMMC_ERR_NONE;
}

// TODO: Set the timeout based on clock speed (Tmio uses SDCLK for timeouts).
//       The tmio driver sets a sane default but we should calculate it anyway.
static u32 initTranState(SdmmcDev *const dev, const u8 devType, const u32 rca, const u8 spec_vers)
{
	TmioPort *const port = &dev->port;

	if(IS_DEV_MMC(devType)) // (e)MMC.
	{
		// EXT_CSD, non-1 bit bus width and HS timing are only
		// supported by (e)MMC SPEC_VERS 4.1 and higher.
		if(spec_vers > 3) // Version 4.1–4.2–4.3 or higher.
		{
			// The (e)MMC spec says to check the card status after a SWITCH CMD (7.6.1).
			// I think we can get away without checking this because support for HS timing
			// and 4 bit bus width is mandatory for this spec version. If the card is
			// non-standard we will encounter errors on the next CMD anyway.
			// Switch to high speed timing (max. 52 MHz).
			const u32 hsArg = MMC_SWITCH_ARG(MMC_SWITCH_ACC_WR_BYTE, EXT_CSD_HS_TIMING, 1, 0);
			u32 res = TMIO_sendCommand(port, MMC_SWITCH, hsArg);
			if(res != 0) return SDMMC_ERR_SWITCH_HS;
			TMIO_setClock(port, HS_CLOCK);

			// Switch to 4 bit bus mode.
			const u32 busWidthArg = MMC_SWITCH_ARG(MMC_SWITCH_ACC_WR_BYTE, EXT_CSD_BUS_WIDTH, 1, 0);
			res = TMIO_sendCommand(port, MMC_SWITCH, busWidthArg);
			if(res != 0) return SDMMC_ERR_SET_BUS_WIDTH;
			TMIO_setBusWidth(port, 4);

			// We should also check in the EXT_CSD the power budget for the card.
			// Nintendo seems to leave it on default (no change).

			if(devType == DEV_TYPE_MMCHC)
			{
				// Note: The EXT_CSD is normally read before touching HS timing and bus width.
				//       We can take advantage of the faster data transfer with this order.
				alignas(4) u8 ext_csd[512];
				TMIO_setBuffer(port, (u32*)ext_csd, 1);
				res = TMIO_sendCommand(port, MMC_SEND_EXT_CSD, 0);
				if(res != 0) return SDMMC_ERR_SEND_EXT_CSD;

				// Get sector count from EXT_CSD only if sector addressing is used because
				// byte addressed (e)MMC may set sector count to 0.
				dev->sectors = ext_csd[EXT_CSD_SEC_COUNT + 3]<<24 | ext_csd[EXT_CSD_SEC_COUNT + 2]<<16 |
				               ext_csd[EXT_CSD_SEC_COUNT + 1]<<8  | ext_csd[EXT_CSD_SEC_COUNT + 0];
			}
		}
	}
	else // SD card.
	{
		// Remove DAT3 pull-up. Linux doesn't do it but the SD spec recommends it.
		u32 res = sendAppCmd(port, SD_APP_SET_CLR_CARD_DETECT, 0, rca); // arg = 0 removes the pull-up.
		if(res != 0) return SDMMC_ERR_SET_CLR_CD;

		// Switch to 4 bit bus mode.
		res = sendAppCmd(port, SD_APP_SET_BUS_WIDTH, 2, rca); // arg = 2 is 4 bit bus width.
		if(res != 0) return SDMMC_ERR_SET_BUS_WIDTH;
		TMIO_setBusWidth(port, 4);

		if(dev->ccc & BIT(10)) // Class 10 command support.
		{
			// Set 64 bytes block length for SWITCH_FUNC status.
			TMIO_setBlockLen(port, 64);

			alignas(4) u8 switchStat[64]; // MSB first and big endian.
			TMIO_setBuffer(port, (u32*)switchStat, 1);
			const u32 arg = SD_SWITCH_FUNC_ARG(1, 0xF, 0xF, 0xF, 1);
			res = TMIO_sendCommand(port, SD_SWITCH_FUNC, arg);
			if(res != 0) return SDMMC_ERR_SWITCH_HS;

			// Restore default 512 bytes block length.
			TMIO_setBlockLen(port, 512);

			// [415:400] Support Bits of Functions in Function Group 1.
			if(switchStat[63u - 400 / 8] & BIT(1)) // Is group 1, function 1 "High-Speed" supported?
			{
				// High-Speed (max. 50 MHz at 3.3V) supported. Switch to highest supported clock.
				TMIO_setClock(port, HS_CLOCK);
			}
		}
	}

	// SD:     The description for CMD SET_BLOCKLEN says 512 bytes is the default.
	// (e)MMC: The description for READ_BL_LEN (CSD) says 512 bytes is the default.
	// So it's not required to set the block length.

	return SDMMC_ERR_NONE;
}

ALWAYS_INLINE u8 dev2portNum(const u8 devNum)
{
	return (devNum == SDMMC_DEV_eMMC ? TMIO_eMMC_PORT : TMIO_CARD_PORT);
}

u32 SDMMC_init(const u8 devNum)
{
	if(devNum > SDMMC_MAX_DEV_NUM) return SDMMC_ERR_INVAL_PARAM;

	SdmmcDev *const dev = &g_devs[devNum];
	if(dev->type != DEV_TYPE_NONE) return SDMMC_ERR_INITIALIZED;

	// Check SD card write protection slider.
	if(devNum == SDMMC_DEV_CARD)
		dev->prot = !TMIO_cardWritable();

	// Init port, enable clock output and wait 74 clocks.
	TmioPort *const port = &dev->port;
	TMIO_initPort(port, dev2portNum(devNum));
	TMIO_powerupSequence(port); // Setup continuous clock and wait 74 clocks.

	u32 res = goIdleState(port);
	if(res != SDMMC_ERR_NONE) return res;

	// (e)MMC/SD now in idle state (idle).
	u8 devType;
	res = initIdleState(port, &devType);
	if(res != SDMMC_ERR_NONE) return res;

	// Stop clock at idle, init clock.
	TMIO_setClock(port, INIT_CLOCK);

	// (e)MMC/SD now in ready state (ready).
	res = initReadyState(dev);
	if(res != SDMMC_ERR_NONE) return res;

	// (e)MMC/SD now in identification state (ident).
	u32 rca;
	res = initIdentState(dev, devType, &rca);
	if(res != SDMMC_ERR_NONE) return res;

	// (e)MMC/SD now in stand-by state (stby).
	// Maximum at this point would be 20 MHz for (e)MMC and 25 for SD.
	// SD: We can increase the clock after end of identification state.
	// TODO: eMMC spec section 7.6
	// "Until the contents of the CSD register is known by the host,
	// the fPP clock rate must remain at fOD. (See Section 12.7 on page 176.)"
	// Since the absolute minimum clock rate is 20 MHz and we are in push-pull
	// mode already can we cheat and switch to <=20 MHz before getting the CSD?
	// Note: This seems to be working just fine in all tests.
	TMIO_setClock(port, DEFAULT_CLOCK);

	u8 spec_vers;
	res = initStandbyState(dev, devType, rca, &spec_vers);
	if(res != SDMMC_ERR_NONE) return res;

	// (e)MMC/SD now in transfer state (tran).
	res = initTranState(dev, devType, rca, spec_vers);
	if(res != SDMMC_ERR_NONE) return res;

	// Only set dev type on successful init.
	dev->type = devType;

	return SDMMC_ERR_NONE;
}

u32 SDMMC_setSleepMode(const u8 devNum, const bool enabled)
{
	if(devNum > SDMMC_MAX_DEV_NUM) return SDMMC_ERR_INVAL_PARAM;

	SdmmcDev *const dev = &g_devs[devNum];
	TmioPort *const port = &dev->port;
	const u32 rca = (u32)dev->rca<<16;
	const u8 devType = dev->type;
	if(enabled)
	{
		// Deselect card to go back to stand-by state.
		// CMD is the same for (e)MMC/SD.
		u32 res = TMIO_sendCommand(port, MMC_DESELECT_CARD, 0);
		if(res != 0) return SDMMC_ERR_SELECT_CARD;

		// Only (e)MMC can go into true sleep mode.
		if(IS_DEV_MMC(devType))
		{
			// Switch (e)MMC into sleep mode.
			res = TMIO_sendCommand(port, MMC_SLEEP_AWAKE, rca | BIT(15));
			if(res != 0) return SDMMC_ERR_SLEEP_AWAKE;
			// TODO: Power down eMMC. This is confirmed working on 3DS.
		}
	}
	else
	{
		if(IS_DEV_MMC(devType))
		{
			// TODO: Power up eMMC. This is confirmed working on 3DS.
			// Wake (e)MMC up from sleep mode.
			u32 res = TMIO_sendCommand(port, MMC_SLEEP_AWAKE, rca);
			if(res != 0) return SDMMC_ERR_SLEEP_AWAKE;
		}

		// Select card to go back to transfer state.
		// CMD is the same for (e)MMC/SD.
		u32 res = TMIO_sendCommand(port, MMC_SELECT_CARD, rca);
		if(res != 0) return SDMMC_ERR_SELECT_CARD;
	}

	return SDMMC_ERR_NONE;
}

// TODO: Is there any "best practice" way of deinitializing cards?
//       Kick the card back into idle state maybe?
//       Linux seems to deselect cards on "suspend".
u32 SDMMC_deinit(const u8 devNum)
{
	if(devNum > SDMMC_MAX_DEV_NUM) return SDMMC_ERR_INVAL_PARAM;

	memset(&g_devs[devNum], 0, sizeof(SdmmcDev));

	return SDMMC_ERR_NONE;
}

u32 SDMMC_lockUnlock(const u8 devNum, const u8 mode, const u8 *const pwd, const u8 pwdLen)
{
	// Password length is maximum 16 bytes except when replacing a password.
	if(devNum > SDMMC_MAX_DEV_NUM || pwdLen > 32) return SDMMC_ERR_INVAL_PARAM;

	// Set block length on (e)MMC/SD side and host.
	// Same CMD for (e)MMC/SD.
	SdmmcDev *const dev = &g_devs[devNum];
	TmioPort *const port = &dev->port;
	const u32 blockLen = (mode != SDMMC_LK_ERASE ? 2 + pwdLen : 1);
	u32 res = TMIO_sendCommand(port, MMC_SET_BLOCKLEN, blockLen);
	if(res != 0) return SDMMC_ERR_SET_BLOCKLEN;
	TMIO_setBlockLen(port, blockLen);

	do
	{
		// Prepare lock/unlock data block.
		alignas(4) u8 buf[36] = {0}; // Size multiple of 4 (TMIO driver limitation).
		buf[0] = mode;
		buf[1] = pwdLen;
		memcpy(&buf[2], pwd, pwdLen);

		// Dirty hack to extend the data timeout to a bit over 4 minutes with TMIO controller.
		// We need 3 minutes minimum for erase.
		const u16 clk_ctrl_backup = port->sd_clk_ctrl;
		TMIO_setClock(port, 130913);

		// Note: Command class 7 support is mandatory for (e)MMC. Not for SD cards until 2.00.
		// Same CMD for (e)MMC/SD.
		TMIO_setBuffer(port, (u32*)buf, 1);
		res = TMIO_sendCommand(port, MMC_LOCK_UNLOCK, 0);
		port->sd_clk_ctrl = clk_ctrl_backup; // Undo the data timeout hack.
		if(res != 0)
		{
			res = SDMMC_ERR_LOCK_UNLOCK;
			break;
		}

		// Restore default block length and get the R1 status.
		// Same CMD for (e)MMC/SD.
		res = TMIO_sendCommand(port, MMC_SET_BLOCKLEN, 512);
		if(res != 0)
		{
			res = SDMMC_ERR_SET_BLOCKLEN;
			break;
		}
		TMIO_setBlockLen(port, 512);

		// Check if lock/unlock worked.
		// Same bit for (e)MMC/SD R1 card status.
		const u32 status = port->resp[0];
		if(status & MMC_R1_LOCK_UNLOCK_FAILED)
			res = SDMMC_ERR_LOCK_UNLOCK_FAIL;

		// Update lock status.
		const u8 prot = dev->prot & ~BIT(3);
		dev->prot = prot | (status>>22 & BIT(3));
	} while(0);

	return res;
}

// People should not mess with the state which is the reason
// why the struct is not exposed directly.
static_assert(sizeof(SdmmcDev) == 64, "Wrong SDMMC dev export/import size.");
u32 SDMMC_exportDevState(const u8 devNum, u8 devOut[64])
{
	if(devNum > SDMMC_MAX_DEV_NUM) return SDMMC_ERR_INVAL_PARAM;

	// Check if the device is initialized.
	const SdmmcDev *const dev = &g_devs[devNum];
	if(dev->type == DEV_TYPE_NONE) return SDMMC_ERR_NO_CARD;

	memcpy(devOut, dev, 64);

	return SDMMC_ERR_NONE;
}

u32 SDMMC_importDevState(const u8 devNum, const u8 devIn[64])
{
	if(devNum > SDMMC_MAX_DEV_NUM) return SDMMC_ERR_INVAL_PARAM;

	// Make sure there is a card inserted.
	if(devNum == SDMMC_DEV_CARD && !TMIO_cardDetected()) return SDMMC_ERR_NO_CARD;

	// Check if the device is initialized.
	SdmmcDev *const dev = &g_devs[devNum];
	if(dev->type != DEV_TYPE_NONE) return SDMMC_ERR_INITIALIZED;

	memcpy(dev, devIn, 64);

	// Update write protection slider state just in case.
	dev->prot |= !TMIO_cardWritable();

	return SDMMC_ERR_NONE;
}

#ifdef __ARM9__
typedef struct
{
	bool initialized;
	bool isMmc;         // Set when the first OP_COND APP CMD fails and MMC init (CMD1) succeeds.
	bool isSd;          // General SD card flag (including SDHC/SDXC). Set when OP_COND APP CMDs succeed.
	bool isSdhc;        // CCS bit from OCR. Set for SDHC and SDXC.
	u32 cid[4];         // In TMIO response format.
	u32 csd[4];         // In TMIO response format.
	u32 ocr;
	u64 scr;            // In big endian? All 0 for (e)MMC.
	u16 rca;
	u8 rsvd[2];
	u32 result;         // Last driver result/error code.
	u32 cardStatus;     // Last R1 card status.
	u16 sd_clk_ctrl;
	u16 sd_option;
	bool highCapacity;  // (SD) Set when CSD v2.0 (NOT v3.0) or (MMC) when the capacity from CSD is higher than 2 GiB.
	u8 rsvd2[3];
	u32 sectors;        // Capacity in sectors.
	u32 sdProtSectors;  // Capacity in sectors of SD protected area from 512 bit SD status. 0 for (e)MMC.

	u32 initFails;      // Failed init attempts?
	u32 initFailResult; // Init fail result? Same format as result?
	u32 rwFails;        // Failed read/write attempts?
	u32 rwFailResult;   // Read/write fail result? Same format as result?

	u32 controller;     // TMIO controller number (1-based).
	u32 portNum;        // TMIO port number.
} HosSdmmcPortCtx;
static_assert(offsetof(HosSdmmcPortCtx, portNum) == 0x60, "Member portNum of HosSdmmcPortCtx not at offset 0x60.");

u32 SDMMC_importHosEmmcState(void)
{
	// Check if the device is already initialized.
	SdmmcDev *const dev = &g_devs[SDMMC_DEV_eMMC];
	if(dev->type != DEV_TYPE_NONE) return SDMMC_ERR_INITIALIZED;

	// Check if the HOS port ctx is initialized.
	const HosSdmmcPortCtx *const ctx = (HosSdmmcPortCtx*)0x01FFCD80;
	if(!ctx->initialized) return SDMMC_ERR_NO_CARD;

	TmioPort *const port = &dev->port;
	port->portNum     = dev2portNum(SDMMC_DEV_eMMC);
	port->sd_clk_ctrl = ctx->sd_clk_ctrl;
	port->sd_blocklen = 512;              // Assumption.
	port->sd_option   = (ctx->sd_option & 0xFF00u) | OPTION_DEFAULT_TIMINGS; // Use our own timings.
	// Remaining fields don't matter.

	u8 devType;
	if(ctx->isMmc && !ctx->isSd)
	{
		// Because Nintendos driver never sets the sector addressing bit
		// in the argument for CMD1, high capacity eMMC will not work.
		// We do the check here anyway just in case.
		devType = (ctx->highCapacity ? DEV_TYPE_MMCHC : DEV_TYPE_MMC);
	}
	else
	{
		// Unfortunately no flags for detecting SDUC.
		devType = (ctx->isSdhc ? DEV_TYPE_SDHC : DEV_TYPE_SDSC);
	}
	dev->type = devType;

	// CSD is in TMIO response format.
	u32 csd[4];
	const u32 *const csdPtr = ctx->csd;
	csd[0] = csdPtr[3]<<8 | csdPtr[2]>>24;
	csd[1] = csdPtr[2]<<8 | csdPtr[1]>>24;
	csd[2] = csdPtr[1]<<8 | csdPtr[0]>>24;
	csd[3] = csdPtr[0]<<8;

	// Parse write protection and password protection bits.
	// Since boot9 doesn't support password protection
	// we could omit parsing that bit. We do it anyway.
	u8 prot = extractBits(csd, 12, 1)<<1; // [12:12]
	prot |= extractBits(csd, 13, 1)<<2;   // [13:13]
	prot |= (ctx->cardStatus & MMC_R1_CARD_IS_LOCKED)>>22; // Bit 3.

	dev->prot    = prot;
	dev->rca     = ctx->rca;
	dev->ccc     = extractBits(csd, 84, 12); // [95:84]
	dev->sectors = ctx->sectors;

	// CID is in TMIO response format.
	u32 *const dstCid = dev->cid;
	const u32 *const srcCid = ctx->cid;
	dstCid[0] = srcCid[3]<<8 | srcCid[2]>>24;
	dstCid[1] = srcCid[2]<<8 | srcCid[1]>>24;
	dstCid[2] = srcCid[1]<<8 | srcCid[0]>>24;
	dstCid[3] = srcCid[0]<<8;

	return SDMMC_ERR_NONE;
}
#endif // #ifdef __ARM9__

// TODO: Less controller dependent code.
u32 SDMMC_getDevInfo(const u8 devNum, SdmmcInfo *const infoOut)
{
	if(devNum > SDMMC_MAX_DEV_NUM) return SDMMC_ERR_INVAL_PARAM;

	const SdmmcDev *const dev = &g_devs[devNum];
	const TmioPort *const port = &dev->port;

	infoOut->type    = dev->type;
	infoOut->prot    = dev->prot;
	infoOut->rca     = dev->rca;
	infoOut->sectors = dev->sectors;

	const u32 clkSetting = port->sd_clk_ctrl & 0xFFu;
	infoOut->clock       = TMIO_HCLK / (clkSetting ? clkSetting<<2 : 2);

	memcpy(infoOut->cid, dev->cid, 16);
	infoOut->ccc      = dev->ccc;
	infoOut->busWidth = (port->sd_option & OPTION_BUS_WIDTH1 ? 1 : 4);

	return SDMMC_ERR_NONE;
}

u32 SDMMC_getCid(const u8 devNum, u32 cidOut[4])
{
	if(devNum > SDMMC_MAX_DEV_NUM) return SDMMC_ERR_INVAL_PARAM;

	if(cidOut != NULL) memcpy(cidOut, g_devs[devNum].cid, 16);

	return SDMMC_ERR_NONE;
}

#include "fatfs/ff.h" // Needed for the "byte" type used in diskio.h.
#include "fatfs/diskio.h"
u8 SDMMC_getDiskStatus(const u8 devNum)
{
	if(devNum > SDMMC_MAX_DEV_NUM) return STA_NODISK | STA_NOINIT;

	u8 status = 0;
	if(devNum == SDMMC_DEV_CARD)
		status = (TMIO_cardDetected() == true ? 0 : STA_NODISK | STA_NOINIT);

	const SdmmcDev *const dev = &g_devs[devNum];
	status |= (dev->prot != 0 ? STA_PROTECT : 0);
	if(dev->type == DEV_TYPE_NONE)
		status |= STA_NOINIT;

	// "Not valid if STA_NODISK is set."
	/*if(status & STA_NODISK)
		status &= ~STA_PROTECT;*/

	return status;
}

u32 SDMMC_getSectors(const u8 devNum)
{
	if(devNum > SDMMC_MAX_DEV_NUM) return 0;

	return g_devs[devNum].sectors;
}

static u32 updateStatus(SdmmcDev *const dev, const bool stopTransmission)
{
	TmioPort *const port = &dev->port;

	// MMC_STOP_TRANSMISSION: Same CMD for (e)MMC/SD. Relies on the driver returning a proper response.
	// MMC_SEND_STATUS:       Same CMD for (e)MMC/SD but the argument format differs slightly.
	u32 res;
	if(stopTransmission) res = TMIO_sendCommand(port, MMC_STOP_TRANSMISSION, 0);
	else                 res = TMIO_sendCommand(port, MMC_SEND_STATUS, (u32)dev->rca<<16);
	dev->status = (res == 0 ? port->resp[0] : 0); // Don't update the status with stale data.

	return res;
}

// Note: On multi-block read from the last 2 sectors there are no errors reported by the controller
//       however the R1 card status may report ADDRESS_OUT_OF_RANGE on next(?) status read.
//       This error is normal for (e)MMC and can be ignored.
u32 SDMMC_readSectors(const u8 devNum, u32 sect, void *const buf, const u16 count)
{
	if(devNum > SDMMC_MAX_DEV_NUM || count == 0) return SDMMC_ERR_INVAL_PARAM;

	// Check if the device is initialized.
	SdmmcDev *const dev = &g_devs[devNum];
	const u8 devType = dev->type;
	if(devType == DEV_TYPE_NONE) return SDMMC_ERR_NO_CARD;

	// Set destination buffer and sector count.
	TmioPort *const port = &dev->port;
	TMIO_setBuffer(port, buf, count);

	// Read a single 512 bytes block. Same CMD for (e)MMC/SD.
	// Read multiple 512 bytes blocks. Same CMD for (e)MMC/SD.
	const u16 readCmd = (count == 1 ? MMC_READ_SINGLE_BLOCK : MMC_READ_MULTIPLE_BLOCK);
	if(devType == DEV_TYPE_MMC || devType == DEV_TYPE_SDSC) sect *= 512; // Byte addressing.
	u32 res = TMIO_sendCommand(port, readCmd, sect);
	if(res != 0)
	{
		// On error in the middle of multi-block reads the card will be stuck
		// in data state and we need to send STOP_TRANSMISSION to bring it
		// back to tran state.
		// Otherwise for single-block reads just update the status.
		updateStatus(dev, count > 1);

		return SDMMC_ERR_SECT_RW;
	}

	return SDMMC_ERR_NONE;
}

// Note: On multi-block write to the last 2 sectors there are no errors reported by the controller
//       however the R1 card status may report ADDRESS_OUT_OF_RANGE on next(?) status read.
//       This error is normal for (e)MMC and can be ignored.
u32 SDMMC_writeSectors(const u8 devNum, u32 sect, const void *const buf, const u16 count)
{
	if(devNum > SDMMC_MAX_DEV_NUM || count == 0) return SDMMC_ERR_INVAL_PARAM;

	// Check if the device is initialized.
	SdmmcDev *const dev = &g_devs[devNum];
	const u8 devType = dev->type;
	if(devType == DEV_TYPE_NONE) return SDMMC_ERR_NO_CARD;

	// Check if the device is write protected.
	if(dev->prot != 0) return SDMMC_ERR_WRITE_PROT;

	// Set source buffer and sector count.
	TmioPort *const port = &dev->port;
	TMIO_setBuffer(port, (void*)buf, count);

	// Write a single 512 bytes block. Same CMD for (e)MMC/SD.
	// Write multiple 512 bytes blocks. Same CMD for (e)MMC/SD.
	const u16 writeCmd = (count == 1 ? MMC_WRITE_BLOCK : MMC_WRITE_MULTIPLE_BLOCK);
	if(devType == DEV_TYPE_MMC || devType == DEV_TYPE_SDSC) sect *= 512; // Byte addressing.
	const u32 res = TMIO_sendCommand(port, writeCmd, sect);
	if(res != 0)
	{
		// On error in the middle of multi-block writes the card will be stuck
		// in data state and we need to send STOP_TRANSMISSION to bring it
		// back to tran state.
		// Otherwise for single-block writes just update the status.
		updateStatus(dev, count > 1);

		return SDMMC_ERR_SECT_RW;
	}

	return SDMMC_ERR_NONE;
}

u32 SDMMC_sendCommand(const u8 devNum, MmcCommand *const mmcCmd)
{
	if(devNum > SDMMC_MAX_DEV_NUM) return SDMMC_ERR_INVAL_PARAM;

	SdmmcDev *const dev = &g_devs[devNum];
	TmioPort *const port = &dev->port;
	TMIO_setBlockLen(port, mmcCmd->blkLen);
	TMIO_setBuffer(port, mmcCmd->buf, mmcCmd->count);

	const u32 res = TMIO_sendCommand(port, mmcCmd->cmd, mmcCmd->arg);
	TMIO_setBlockLen(port, 512); // Restore default block length.
	if(res != 0)
	{
		updateStatus(dev, false);
		return SDMMC_ERR_SEND_CMD;
	}

	memcpy(mmcCmd->resp, port->resp, 16);

	return SDMMC_ERR_NONE;
}

u32 SDMMC_getLastR1error(const u8 devNum)
{
	if(devNum > SDMMC_MAX_DEV_NUM) return 0;

	SdmmcDev *const dev = &g_devs[devNum];
	const u32 status = dev->status;
	dev->status = 0;

	return status;
}