drivers/mtd/spi/sandbox.c - platform/external/u-boot - Gitiles

 /*
  * Simulate a SPI flash
  *
  * Copyright (c) 2011-2013 The Chromium OS Authors.
  * See file CREDITS for list of people who contributed to this
  * project.
  *
  * Licensed under the GPL-2 or later.
  */

 #define LOG_CATEGORY UCLASS_SPI_FLASH

 #include <common.h>
 #include <dm.h>
 #include <log.h>
 #include <malloc.h>
 #include <spi.h>
 #include <os.h>

 #include <spi_flash.h>
 #include "sf_internal.h"

 #include <asm/getopt.h>
 #include <asm/spi.h>
 #include <asm/state.h>
 #include <dm/device-internal.h>
 #include <dm/lists.h>
 #include <dm/uclass-internal.h>

 /*
  * The different states that our SPI flash transitions between.
  * We need to keep track of this across multiple xfer calls since
  * the SPI bus could possibly call down into us multiple times.
  */
 enum sandbox_sf_state {
 	SF_CMD,   /* default state -- we're awaiting a command */
 	SF_ID,    /* read the flash's (jedec) ID code */
 	SF_ADDR,  /* processing the offset in the flash to read/etc... */
 	SF_READ,  /* reading data from the flash */
 	SF_WRITE, /* writing data to the flash, i.e. page programming */
 	SF_ERASE, /* erase the flash */
 	SF_READ_STATUS, /* read the flash's status register */
 	SF_READ_STATUS1, /* read the flash's status register upper 8 bits*/
 	SF_WRITE_STATUS, /* write the flash's status register */
 };

 #if CONFIG_IS_ENABLED(LOG)
 static const char *sandbox_sf_state_name(enum sandbox_sf_state state)
 {
 	static const char * const states[] = {
 		"CMD", "ID", "ADDR", "READ", "WRITE", "ERASE", "READ_STATUS",
 		"READ_STATUS1", "WRITE_STATUS",
 	};
 	return states[state];
 }
 #endif /* LOG */

 /* Bits for the status register */
 #define STAT_WIP	(1 << 0)
 #define STAT_WEL	(1 << 1)
 #define STAT_BP_SHIFT	2
 #define STAT_BP_MASK	(7 << STAT_BP_SHIFT)

 /* Assume all SPI flashes have 3 byte addresses since they do atm */
 #define SF_ADDR_LEN	3

 #define IDCODE_LEN 3

 /* Used to quickly bulk erase backing store */
 static u8 sandbox_sf_0xff[0x1000];

 /* Internal state data for each SPI flash */
 struct sandbox_spi_flash {
 	unsigned int cs;	/* Chip select we are attached to */
 	/*
 	 * As we receive data over the SPI bus, our flash transitions
 	 * between states.  For example, we start off in the SF_CMD
 	 * state where the first byte tells us what operation to perform
 	 * (such as read or write the flash).  But the operation itself
 	 * can go through a few states such as first reading in the
 	 * offset in the flash to perform the requested operation.
 	 * Thus "state" stores the exact state that our machine is in
 	 * while "cmd" stores the overall command we're processing.
 	 */
 	enum sandbox_sf_state state;
 	uint cmd;
 	/* Erase size of current erase command */
 	uint erase_size;
 	/* Current position in the flash; used when reading/writing/etc... */
 	uint off;
 	/* How many address bytes we've consumed */
 	uint addr_bytes, pad_addr_bytes;
 	/* The current flash status (see STAT_XXX defines above) */
 	u16 status;
 	/* Data describing the flash we're emulating */
 	const struct flash_info *data;
 	/* The file on disk to serv up data from */
 	int fd;
 };

 struct sandbox_spi_flash_plat_data {
 	const char *filename;
 	const char *device_name;
 	int bus;
 	int cs;
 };

 void sandbox_sf_set_block_protect(struct udevice *dev, int bp_mask)
 {
 	struct sandbox_spi_flash *sbsf = dev_get_priv(dev);

 	sbsf->status &= ~STAT_BP_MASK;
 	sbsf->status |= bp_mask << STAT_BP_SHIFT;
 }

 /**
  * This is a very strange probe function. If it has platform data (which may
  * have come from the device tree) then this function gets the filename and
  * device type from there.
  */
 static int sandbox_sf_probe(struct udevice *dev)
 {
 	/* spec = idcode:file */
 	struct sandbox_spi_flash *sbsf = dev_get_priv(dev);
 	size_t len, idname_len;
 	const struct flash_info *data;
 	struct sandbox_spi_flash_plat_data *pdata = dev_get_platdata(dev);
 	struct sandbox_state *state = state_get_current();
 	struct dm_spi_slave_platdata *slave_plat;
 	struct udevice *bus = dev->parent;
 	const char *spec = NULL;
 	struct udevice *emul;
 	int ret = 0;
 	int cs = -1;

 	debug("%s: bus %d, looking for emul=%p: ", __func__, bus->seq, dev);
 	ret = sandbox_spi_get_emul(state, bus, dev, &emul);
 	if (ret) {
 		printf("Error: Unknown chip select for device '%s'\n",
 			dev->name);
 		return ret;
 	}
 	slave_plat = dev_get_parent_platdata(dev);
 	cs = slave_plat->cs;
 	debug("found at cs %d\n", cs);

 	if (!pdata->filename) {
 		printf("Error: No filename available\n");
 		return -EINVAL;
 	}
 	spec = strchr(pdata->device_name, ',');
 	if (spec)
 		spec++;
 	else
 		spec = pdata->device_name;
 	idname_len = strlen(spec);
 	debug("%s: device='%s'\n", __func__, spec);

 	for (data = spi_nor_ids; data->name; data++) {
 		len = strlen(data->name);
 		if (idname_len != len)
 			continue;
 		if (!strncasecmp(spec, data->name, len))
 			break;
 	}
 	if (!data->name) {
 		printf("%s: unknown flash '%*s'\n", __func__, (int)idname_len,
 		       spec);
 		ret = -EINVAL;
 		goto error;
 	}

 	if (sandbox_sf_0xff[0] == 0x00)
 		memset(sandbox_sf_0xff, 0xff, sizeof(sandbox_sf_0xff));

 	sbsf->fd = os_open(pdata->filename, 02);
 	if (sbsf->fd == -1) {
 		printf("%s: unable to open file '%s'\n", __func__,
 		       pdata->filename);
 		ret = -EIO;
 		goto error;
 	}

 	sbsf->data = data;
 	sbsf->cs = cs;

 	return 0;

  error:
 	debug("%s: Got error %d\n", __func__, ret);
 	return ret;
 }

 static int sandbox_sf_remove(struct udevice *dev)
 {
 	struct sandbox_spi_flash *sbsf = dev_get_priv(dev);

 	os_close(sbsf->fd);

 	return 0;
 }

 static void sandbox_sf_cs_activate(struct udevice *dev)
 {
 	struct sandbox_spi_flash *sbsf = dev_get_priv(dev);

 	log_content("sandbox_sf: CS activated; state is fresh!\n");

 	/* CS is asserted, so reset state */
 	sbsf->off = 0;
 	sbsf->addr_bytes = 0;
 	sbsf->pad_addr_bytes = 0;
 	sbsf->state = SF_CMD;
 	sbsf->cmd = SF_CMD;
 }

 static void sandbox_sf_cs_deactivate(struct udevice *dev)
 {
 	log_content("sandbox_sf: CS deactivated; cmd done processing!\n");
 }

 /*
  * There are times when the data lines are allowed to tristate.  What
  * is actually sensed on the line depends on the hardware.  It could
  * always be 0xFF/0x00 (if there are pull ups/downs), or things could
  * float and so we'd get garbage back.  This func encapsulates that
  * scenario so we can worry about the details here.
  */
 static void sandbox_spi_tristate(u8 *buf, uint len)
 {
 	/* XXX: make this into a user config option ? */
 	memset(buf, 0xff, len);
 }

 /* Figure out what command this stream is telling us to do */
 static int sandbox_sf_process_cmd(struct sandbox_spi_flash *sbsf, const u8 *rx,
 				  u8 *tx)
 {
 	enum sandbox_sf_state oldstate = sbsf->state;

 	/* We need to output a byte for the cmd byte we just ate */
 	if (tx)
 		sandbox_spi_tristate(tx, 1);

 	sbsf->cmd = rx[0];
 	switch (sbsf->cmd) {
 	case SPINOR_OP_RDID:
 		sbsf->state = SF_ID;
 		sbsf->cmd = SF_ID;
 		break;
 	case SPINOR_OP_READ_FAST:
 		sbsf->pad_addr_bytes = 1;
 	case SPINOR_OP_READ:
 	case SPINOR_OP_PP:
 		sbsf->state = SF_ADDR;
 		break;
 	case SPINOR_OP_WRDI:
 		debug(" write disabled\n");
 		sbsf->status &= ~STAT_WEL;
 		break;
 	case SPINOR_OP_RDSR:
 		sbsf->state = SF_READ_STATUS;
 		break;
 	case SPINOR_OP_RDSR2:
 		sbsf->state = SF_READ_STATUS1;
 		break;
 	case SPINOR_OP_WREN:
 		debug(" write enabled\n");
 		sbsf->status |= STAT_WEL;
 		break;
 	case SPINOR_OP_WRSR:
 		sbsf->state = SF_WRITE_STATUS;
 		break;
 	default: {
 		int flags = sbsf->data->flags;

 		/* we only support erase here */
 		if (sbsf->cmd == SPINOR_OP_CHIP_ERASE) {
 			sbsf->erase_size = sbsf->data->sector_size *
 				sbsf->data->n_sectors;
 		} else if (sbsf->cmd == SPINOR_OP_BE_4K && (flags & SECT_4K)) {
 			sbsf->erase_size = 4 << 10;
 		} else if (sbsf->cmd == SPINOR_OP_SE && !(flags & SECT_4K)) {
 			sbsf->erase_size = 64 << 10;
 		} else {
 			debug(" cmd unknown: %#x\n", sbsf->cmd);
 			return -EIO;
 		}
 		sbsf->state = SF_ADDR;
 		break;
 	}
 	}

 	if (oldstate != sbsf->state)
 		log_content(" cmd: transition to %s state\n",
 			    sandbox_sf_state_name(sbsf->state));

 	return 0;
 }

 int sandbox_erase_part(struct sandbox_spi_flash *sbsf, int size)
 {
 	int todo;
 	int ret;

 	while (size > 0) {
 		todo = min(size, (int)sizeof(sandbox_sf_0xff));
 		ret = os_write(sbsf->fd, sandbox_sf_0xff, todo);
 		if (ret != todo)
 			return ret;
 		size -= todo;
 	}

 	return 0;
 }

 static int sandbox_sf_xfer(struct udevice *dev, unsigned int bitlen,
 			   const void *rxp, void *txp, unsigned long flags)
 {
 	struct sandbox_spi_flash *sbsf = dev_get_priv(dev);
 	const uint8_t *rx = rxp;
 	uint8_t *tx = txp;
 	uint cnt, pos = 0;
 	int bytes = bitlen / 8;
 	int ret;

 	log_content("sandbox_sf: state:%x(%s) bytes:%u\n", sbsf->state,
 		    sandbox_sf_state_name(sbsf->state), bytes);

 	if ((flags & SPI_XFER_BEGIN))
 		sandbox_sf_cs_activate(dev);

 	if (sbsf->state == SF_CMD) {
 		/* Figure out the initial state */
 		ret = sandbox_sf_process_cmd(sbsf, rx, tx);
 		if (ret)
 			return ret;
 		++pos;
 	}

 	/* Process the remaining data */
 	while (pos < bytes) {
 		switch (sbsf->state) {
 		case SF_ID: {
 			u8 id;

 			log_content(" id: off:%u tx:", sbsf->off);
 			if (sbsf->off < IDCODE_LEN) {
 				/* Extract correct byte from ID 0x00aabbcc */
 				id = ((JEDEC_MFR(sbsf->data) << 16) |
 					JEDEC_ID(sbsf->data)) >>
 					(8 * (IDCODE_LEN - 1 - sbsf->off));
 			} else {
 				id = 0;
 			}
 			log_content("%d %02x\n", sbsf->off, id);
 			tx[pos++] = id;
 			++sbsf->off;
 			break;
 		}
 		case SF_ADDR:
 			log_content(" addr: bytes:%u rx:%02x ",
 				    sbsf->addr_bytes, rx[pos]);

 			if (sbsf->addr_bytes++ < SF_ADDR_LEN)
 				sbsf->off = (sbsf->off << 8) | rx[pos];
 			log_content("addr:%06x\n", sbsf->off);

 			if (tx)
 				sandbox_spi_tristate(&tx[pos], 1);
 			pos++;

 			/* See if we're done processing */
 			if (sbsf->addr_bytes <
 					SF_ADDR_LEN + sbsf->pad_addr_bytes)
 				break;

 			/* Next state! */
 			if (os_lseek(sbsf->fd, sbsf->off, OS_SEEK_SET) < 0) {
 				puts("sandbox_sf: os_lseek() failed");
 				return -EIO;
 			}
 			switch (sbsf->cmd) {
 			case SPINOR_OP_READ_FAST:
 			case SPINOR_OP_READ:
 				sbsf->state = SF_READ;
 				break;
 			case SPINOR_OP_PP:
 				sbsf->state = SF_WRITE;
 				break;
 			default:
 				/* assume erase state ... */
 				sbsf->state = SF_ERASE;
 				goto case_sf_erase;
 			}
 			log_content(" cmd: transition to %s state\n",
 				    sandbox_sf_state_name(sbsf->state));
 			break;
 		case SF_READ:
 			/*
 			 * XXX: need to handle exotic behavior:
 			 *      - reading past end of device
 			 */

 			cnt = bytes - pos;
 			log_content(" tx: read(%u)\n", cnt);
 			assert(tx);
 			ret = os_read(sbsf->fd, tx + pos, cnt);
 			if (ret < 0) {
 				puts("sandbox_sf: os_read() failed\n");
 				return -EIO;
 			}
 			pos += ret;
 			break;
 		case SF_READ_STATUS:
 			log_content(" read status: %#x\n", sbsf->status);
 			cnt = bytes - pos;
 			memset(tx + pos, sbsf->status, cnt);
 			pos += cnt;
 			break;
 		case SF_READ_STATUS1:
 			log_content(" read status: %#x\n", sbsf->status);
 			cnt = bytes - pos;
 			memset(tx + pos, sbsf->status >> 8, cnt);
 			pos += cnt;
 			break;
 		case SF_WRITE_STATUS:
 			log_content(" write status: %#x (ignored)\n", rx[pos]);
 			pos = bytes;
 			break;
 		case SF_WRITE:
 			/*
 			 * XXX: need to handle exotic behavior:
 			 *      - unaligned addresses
 			 *      - more than a page (256) worth of data
 			 *      - reading past end of device
 			 */
 			if (!(sbsf->status & STAT_WEL)) {
 				puts("sandbox_sf: write enable not set before write\n");
 				goto done;
 			}

 			cnt = bytes - pos;
 			log_content(" rx: write(%u)\n", cnt);
 			if (tx)
 				sandbox_spi_tristate(&tx[pos], cnt);
 			ret = os_write(sbsf->fd, rx + pos, cnt);
 			if (ret < 0) {
 				puts("sandbox_spi: os_write() failed\n");
 				return -EIO;
 			}
 			pos += ret;
 			sbsf->status &= ~STAT_WEL;
 			break;
 		case SF_ERASE:
  case_sf_erase: {
 			if (!(sbsf->status & STAT_WEL)) {
 				puts("sandbox_sf: write enable not set before erase\n");
 				goto done;
 			}

 			/* verify address is aligned */
 			if (sbsf->off & (sbsf->erase_size - 1)) {
 				log_content(" sector erase: cmd:%#x needs align:%#x, but we got %#x\n",
 					    sbsf->cmd, sbsf->erase_size,
 					    sbsf->off);
 				sbsf->status &= ~STAT_WEL;
 				goto done;
 			}

 			log_content(" sector erase addr: %u, size: %u\n",
 				    sbsf->off, sbsf->erase_size);

 			cnt = bytes - pos;
 			if (tx)
 				sandbox_spi_tristate(&tx[pos], cnt);
 			pos += cnt;

 			/*
 			 * TODO(vapier@gentoo.org): latch WIP in status, and
 			 * delay before clearing it ?
 			 */
 			ret = sandbox_erase_part(sbsf, sbsf->erase_size);
 			sbsf->status &= ~STAT_WEL;
 			if (ret) {
 				log_content("sandbox_sf: Erase failed\n");
 				goto done;
 			}
 			goto done;
 		}
 		default:
 			log_content(" ??? no idea what to do ???\n");
 			goto done;
 		}
 	}

  done:
 	if (flags & SPI_XFER_END)
 		sandbox_sf_cs_deactivate(dev);
 	return pos == bytes ? 0 : -EIO;
 }

 int sandbox_sf_ofdata_to_platdata(struct udevice *dev)
 {
 	struct sandbox_spi_flash_plat_data *pdata = dev_get_platdata(dev);

 	pdata->filename = dev_read_string(dev, "sandbox,filename");
 	pdata->device_name = dev_read_string(dev, "compatible");
 	if (!pdata->filename || !pdata->device_name) {
 		debug("%s: Missing properties, filename=%s, device_name=%s\n",
 		      __func__, pdata->filename, pdata->device_name);
 		return -EINVAL;
 	}

 	return 0;
 }

 static const struct dm_spi_emul_ops sandbox_sf_emul_ops = {
 	.xfer          = sandbox_sf_xfer,
 };

 #ifdef CONFIG_SPI_FLASH
 int sandbox_sf_bind_emul(struct sandbox_state *state, int busnum, int cs,
 			 struct udevice *bus, ofnode node, const char *spec)
 {
 	struct udevice *emul;
 	char name[20], *str;
 	struct driver *drv;
 	int ret;

 	/* now the emulator */
 	strncpy(name, spec, sizeof(name) - 6);
 	name[sizeof(name) - 6] = '\0';
 	strcat(name, "-emul");
 	drv = lists_driver_lookup_name("sandbox_sf_emul");
 	if (!drv) {
 		puts("Cannot find sandbox_sf_emul driver\n");
 		return -ENOENT;
 	}
 	str = strdup(name);
 	if (!str)
 		return -ENOMEM;
 	ret = device_bind_ofnode(bus, drv, str, NULL, node, &emul);
 	if (ret) {
 		free(str);
 		printf("Cannot create emul device for spec '%s' (err=%d)\n",
 		       spec, ret);
 		return ret;
 	}
 	state->spi[busnum][cs].emul = emul;

 	return 0;
 }

 void sandbox_sf_unbind_emul(struct sandbox_state *state, int busnum, int cs)
 {
 	struct udevice *dev;

 	dev = state->spi[busnum][cs].emul;
 	device_remove(dev, DM_REMOVE_NORMAL);
 	device_unbind(dev);
 	state->spi[busnum][cs].emul = NULL;
 }

 int sandbox_spi_get_emul(struct sandbox_state *state,
 			 struct udevice *bus, struct udevice *slave,
 			 struct udevice **emulp)
 {
 	struct sandbox_spi_info *info;
 	int busnum = bus->seq;
 	int cs = spi_chip_select(slave);
 	int ret;

 	info = &state->spi[busnum][cs];
 	if (!info->emul) {
 		/* Use the same device tree node as the SPI flash device */
 		debug("%s: busnum=%u, cs=%u: binding SPI flash emulation: ",
 		      __func__, busnum, cs);
 		ret = sandbox_sf_bind_emul(state, busnum, cs, bus,
 					   dev_ofnode(slave), slave->name);
 		if (ret) {
 			debug("failed (err=%d)\n", ret);
 			return ret;
 		}
 		debug("OK\n");
 	}
 	*emulp = info->emul;

 	return 0;
 }
 #endif

 static const struct udevice_id sandbox_sf_ids[] = {
 	{ .compatible = "sandbox,spi-flash" },
 	{ }
 };

 U_BOOT_DRIVER(sandbox_sf_emul) = {
 	.name		= "sandbox_sf_emul",
 	.id		= UCLASS_SPI_EMUL,
 	.of_match	= sandbox_sf_ids,
 	.ofdata_to_platdata = sandbox_sf_ofdata_to_platdata,
 	.probe		= sandbox_sf_probe,
 	.remove		= sandbox_sf_remove,
 	.priv_auto_alloc_size = sizeof(struct sandbox_spi_flash),
 	.platdata_auto_alloc_size = sizeof(struct sandbox_spi_flash_plat_data),
 	.ops		= &sandbox_sf_emul_ops,
 };
	/*
	* Simulate a SPI flash
	*
	* Copyright (c) 2011-2013 The Chromium OS Authors.
	* See file CREDITS for list of people who contributed to this
	* project.
	*
	* Licensed under the GPL-2 or later.
	*/

	#define LOG_CATEGORY UCLASS_SPI_FLASH

	#include <common.h>
	#include <dm.h>
	#include <log.h>
	#include <malloc.h>
	#include <spi.h>
	#include <os.h>

	#include <spi_flash.h>
	#include "sf_internal.h"

	#include <asm/getopt.h>
	#include <asm/spi.h>
	#include <asm/state.h>
	#include <dm/device-internal.h>
	#include <dm/lists.h>
	#include <dm/uclass-internal.h>

	/*
	* The different states that our SPI flash transitions between.
	* We need to keep track of this across multiple xfer calls since
	* the SPI bus could possibly call down into us multiple times.
	*/
	enum sandbox_sf_state {
	SF_CMD, /* default state -- we're awaiting a command */
	SF_ID, /* read the flash's (jedec) ID code */
	SF_ADDR, /* processing the offset in the flash to read/etc... */
	SF_READ, /* reading data from the flash */
	SF_WRITE, /* writing data to the flash, i.e. page programming */
	SF_ERASE, /* erase the flash */
	SF_READ_STATUS, /* read the flash's status register */
	SF_READ_STATUS1, /* read the flash's status register upper 8 bits*/
	SF_WRITE_STATUS, /* write the flash's status register */
	};

	#if CONFIG_IS_ENABLED(LOG)
	static const char *sandbox_sf_state_name(enum sandbox_sf_state state)
	{
	static const char * const states[] = {
	"CMD", "ID", "ADDR", "READ", "WRITE", "ERASE", "READ_STATUS",
	"READ_STATUS1", "WRITE_STATUS",
	};
	return states[state];
	}
	#endif /* LOG */

	/* Bits for the status register */
	#define STAT_WIP (1 << 0)
	#define STAT_WEL (1 << 1)
	#define STAT_BP_SHIFT 2
	#define STAT_BP_MASK (7 << STAT_BP_SHIFT)

	/* Assume all SPI flashes have 3 byte addresses since they do atm */
	#define SF_ADDR_LEN 3

	#define IDCODE_LEN 3

	/* Used to quickly bulk erase backing store */
	static u8 sandbox_sf_0xff[0x1000];

	/* Internal state data for each SPI flash */
	struct sandbox_spi_flash {
	unsigned int cs; /* Chip select we are attached to */
	/*
	* As we receive data over the SPI bus, our flash transitions
	* between states. For example, we start off in the SF_CMD
	* state where the first byte tells us what operation to perform
	* (such as read or write the flash). But the operation itself
	* can go through a few states such as first reading in the
	* offset in the flash to perform the requested operation.
	* Thus "state" stores the exact state that our machine is in
	* while "cmd" stores the overall command we're processing.
	*/
	enum sandbox_sf_state state;
	uint cmd;
	/* Erase size of current erase command */
	uint erase_size;
	/* Current position in the flash; used when reading/writing/etc... */
	uint off;
	/* How many address bytes we've consumed */
	uint addr_bytes, pad_addr_bytes;
	/* The current flash status (see STAT_XXX defines above) */
	u16 status;
	/* Data describing the flash we're emulating */
	const struct flash_info *data;
	/* The file on disk to serv up data from */
	int fd;
	};

	struct sandbox_spi_flash_plat_data {
	const char *filename;
	const char *device_name;
	int bus;
	int cs;
	};

	void sandbox_sf_set_block_protect(struct udevice *dev, int bp_mask)
	{
	struct sandbox_spi_flash *sbsf = dev_get_priv(dev);

	sbsf->status &= ~STAT_BP_MASK;
	sbsf->status \|= bp_mask << STAT_BP_SHIFT;
	}

	/**
	* This is a very strange probe function. If it has platform data (which may
	* have come from the device tree) then this function gets the filename and
	* device type from there.
	*/
	static int sandbox_sf_probe(struct udevice *dev)
	{
	/* spec = idcode:file */
	struct sandbox_spi_flash *sbsf = dev_get_priv(dev);
	size_t len, idname_len;
	const struct flash_info *data;
	struct sandbox_spi_flash_plat_data *pdata = dev_get_platdata(dev);
	struct sandbox_state *state = state_get_current();
	struct dm_spi_slave_platdata *slave_plat;
	struct udevice *bus = dev->parent;
	const char *spec = NULL;
	struct udevice *emul;
	int ret = 0;
	int cs = -1;

	debug("%s: bus %d, looking for emul=%p: ", __func__, bus->seq, dev);
	ret = sandbox_spi_get_emul(state, bus, dev, &emul);
	if (ret) {
	printf("Error: Unknown chip select for device '%s'\n",
	dev->name);
	return ret;
	}
	slave_plat = dev_get_parent_platdata(dev);
	cs = slave_plat->cs;
	debug("found at cs %d\n", cs);

	if (!pdata->filename) {
	printf("Error: No filename available\n");
	return -EINVAL;
	}
	spec = strchr(pdata->device_name, ',');
	if (spec)
	spec++;
	else
	spec = pdata->device_name;
	idname_len = strlen(spec);
	debug("%s: device='%s'\n", __func__, spec);

	for (data = spi_nor_ids; data->name; data++) {
	len = strlen(data->name);
	if (idname_len != len)
	continue;
	if (!strncasecmp(spec, data->name, len))
	break;
	}
	if (!data->name) {
	printf("%s: unknown flash '%*s'\n", __func__, (int)idname_len,
	spec);
	ret = -EINVAL;
	goto error;
	}

	if (sandbox_sf_0xff[0] == 0x00)
	memset(sandbox_sf_0xff, 0xff, sizeof(sandbox_sf_0xff));

	sbsf->fd = os_open(pdata->filename, 02);
	if (sbsf->fd == -1) {
	printf("%s: unable to open file '%s'\n", __func__,
	pdata->filename);
	ret = -EIO;
	goto error;
	}

	sbsf->data = data;
	sbsf->cs = cs;

	return 0;

	error:
	debug("%s: Got error %d\n", __func__, ret);
	return ret;
	}

	static int sandbox_sf_remove(struct udevice *dev)
	{
	struct sandbox_spi_flash *sbsf = dev_get_priv(dev);

	os_close(sbsf->fd);

	return 0;
	}

	static void sandbox_sf_cs_activate(struct udevice *dev)
	{
	struct sandbox_spi_flash *sbsf = dev_get_priv(dev);

	log_content("sandbox_sf: CS activated; state is fresh!\n");

	/* CS is asserted, so reset state */
	sbsf->off = 0;
	sbsf->addr_bytes = 0;
	sbsf->pad_addr_bytes = 0;
	sbsf->state = SF_CMD;
	sbsf->cmd = SF_CMD;
	}

	static void sandbox_sf_cs_deactivate(struct udevice *dev)
	{
	log_content("sandbox_sf: CS deactivated; cmd done processing!\n");
	}

	/*
	* There are times when the data lines are allowed to tristate. What
	* is actually sensed on the line depends on the hardware. It could
	* always be 0xFF/0x00 (if there are pull ups/downs), or things could
	* float and so we'd get garbage back. This func encapsulates that
	* scenario so we can worry about the details here.
	*/
	static void sandbox_spi_tristate(u8 *buf, uint len)
	{
	/* XXX: make this into a user config option ? */
	memset(buf, 0xff, len);
	}

	/* Figure out what command this stream is telling us to do */
	static int sandbox_sf_process_cmd(struct sandbox_spi_flash sbsf, const u8 rx,
	u8 *tx)
	{
	enum sandbox_sf_state oldstate = sbsf->state;

	/* We need to output a byte for the cmd byte we just ate */
	if (tx)
	sandbox_spi_tristate(tx, 1);

	sbsf->cmd = rx[0];
	switch (sbsf->cmd) {
	case SPINOR_OP_RDID:
	sbsf->state = SF_ID;
	sbsf->cmd = SF_ID;
	break;
	case SPINOR_OP_READ_FAST:
	sbsf->pad_addr_bytes = 1;
	case SPINOR_OP_READ:
	case SPINOR_OP_PP:
	sbsf->state = SF_ADDR;
	break;
	case SPINOR_OP_WRDI:
	debug(" write disabled\n");
	sbsf->status &= ~STAT_WEL;
	break;
	case SPINOR_OP_RDSR:
	sbsf->state = SF_READ_STATUS;
	break;
	case SPINOR_OP_RDSR2:
	sbsf->state = SF_READ_STATUS1;
	break;
	case SPINOR_OP_WREN:
	debug(" write enabled\n");
	sbsf->status \|= STAT_WEL;
	break;
	case SPINOR_OP_WRSR:
	sbsf->state = SF_WRITE_STATUS;
	break;
	default: {
	int flags = sbsf->data->flags;

	/* we only support erase here */
	if (sbsf->cmd == SPINOR_OP_CHIP_ERASE) {
	sbsf->erase_size = sbsf->data->sector_size *
	sbsf->data->n_sectors;
	} else if (sbsf->cmd == SPINOR_OP_BE_4K && (flags & SECT_4K)) {
	sbsf->erase_size = 4 << 10;
	} else if (sbsf->cmd == SPINOR_OP_SE && !(flags & SECT_4K)) {
	sbsf->erase_size = 64 << 10;
	} else {
	debug(" cmd unknown: %#x\n", sbsf->cmd);
	return -EIO;
	}
	sbsf->state = SF_ADDR;
	break;
	}
	}

	if (oldstate != sbsf->state)
	log_content(" cmd: transition to %s state\n",
	sandbox_sf_state_name(sbsf->state));

	return 0;
	}

	int sandbox_erase_part(struct sandbox_spi_flash *sbsf, int size)
	{
	int todo;
	int ret;

	while (size > 0) {
	todo = min(size, (int)sizeof(sandbox_sf_0xff));
	ret = os_write(sbsf->fd, sandbox_sf_0xff, todo);
	if (ret != todo)
	return ret;
	size -= todo;
	}

	return 0;
	}

	static int sandbox_sf_xfer(struct udevice *dev, unsigned int bitlen,
	const void rxp, void txp, unsigned long flags)
	{
	struct sandbox_spi_flash *sbsf = dev_get_priv(dev);
	const uint8_t *rx = rxp;
	uint8_t *tx = txp;
	uint cnt, pos = 0;
	int bytes = bitlen / 8;
	int ret;

	log_content("sandbox_sf: state:%x(%s) bytes:%u\n", sbsf->state,
	sandbox_sf_state_name(sbsf->state), bytes);

	if ((flags & SPI_XFER_BEGIN))
	sandbox_sf_cs_activate(dev);

	if (sbsf->state == SF_CMD) {
	/* Figure out the initial state */
	ret = sandbox_sf_process_cmd(sbsf, rx, tx);
	if (ret)
	return ret;
	++pos;
	}

	/* Process the remaining data */
	while (pos < bytes) {
	switch (sbsf->state) {
	case SF_ID: {
	u8 id;

	log_content(" id: off:%u tx:", sbsf->off);
	if (sbsf->off < IDCODE_LEN) {
	/* Extract correct byte from ID 0x00aabbcc */
	id = ((JEDEC_MFR(sbsf->data) << 16) \|
	JEDEC_ID(sbsf->data)) >>
	(8 * (IDCODE_LEN - 1 - sbsf->off));
	} else {
	id = 0;
	}
	log_content("%d %02x\n", sbsf->off, id);
	tx[pos++] = id;
	++sbsf->off;
	break;
	}
	case SF_ADDR:
	log_content(" addr: bytes:%u rx:%02x ",
	sbsf->addr_bytes, rx[pos]);

	if (sbsf->addr_bytes++ < SF_ADDR_LEN)
	sbsf->off = (sbsf->off << 8) \| rx[pos];
	log_content("addr:%06x\n", sbsf->off);

	if (tx)
	sandbox_spi_tristate(&tx[pos], 1);
	pos++;

	/* See if we're done processing */
	if (sbsf->addr_bytes <
	SF_ADDR_LEN + sbsf->pad_addr_bytes)
	break;

	/* Next state! */
	if (os_lseek(sbsf->fd, sbsf->off, OS_SEEK_SET) < 0) {
	puts("sandbox_sf: os_lseek() failed");
	return -EIO;
	}
	switch (sbsf->cmd) {
	case SPINOR_OP_READ_FAST:
	case SPINOR_OP_READ:
	sbsf->state = SF_READ;
	break;
	case SPINOR_OP_PP:
	sbsf->state = SF_WRITE;
	break;
	default:
	/* assume erase state ... */
	sbsf->state = SF_ERASE;
	goto case_sf_erase;
	}
	log_content(" cmd: transition to %s state\n",
	sandbox_sf_state_name(sbsf->state));
	break;
	case SF_READ:
	/*
	* XXX: need to handle exotic behavior:
	* - reading past end of device
	*/

	cnt = bytes - pos;
	log_content(" tx: read(%u)\n", cnt);
	assert(tx);
	ret = os_read(sbsf->fd, tx + pos, cnt);
	if (ret < 0) {
	puts("sandbox_sf: os_read() failed\n");
	return -EIO;
	}
	pos += ret;
	break;
	case SF_READ_STATUS:
	log_content(" read status: %#x\n", sbsf->status);
	cnt = bytes - pos;
	memset(tx + pos, sbsf->status, cnt);
	pos += cnt;
	break;
	case SF_READ_STATUS1:
	log_content(" read status: %#x\n", sbsf->status);
	cnt = bytes - pos;
	memset(tx + pos, sbsf->status >> 8, cnt);
	pos += cnt;
	break;
	case SF_WRITE_STATUS:
	log_content(" write status: %#x (ignored)\n", rx[pos]);
	pos = bytes;
	break;
	case SF_WRITE:
	/*
	* XXX: need to handle exotic behavior:
	* - unaligned addresses
	* - more than a page (256) worth of data
	* - reading past end of device
	*/
	if (!(sbsf->status & STAT_WEL)) {
	puts("sandbox_sf: write enable not set before write\n");
	goto done;
	}

	cnt = bytes - pos;
	log_content(" rx: write(%u)\n", cnt);
	if (tx)
	sandbox_spi_tristate(&tx[pos], cnt);
	ret = os_write(sbsf->fd, rx + pos, cnt);
	if (ret < 0) {
	puts("sandbox_spi: os_write() failed\n");
	return -EIO;
	}
	pos += ret;
	sbsf->status &= ~STAT_WEL;
	break;
	case SF_ERASE:
	case_sf_erase: {
	if (!(sbsf->status & STAT_WEL)) {
	puts("sandbox_sf: write enable not set before erase\n");
	goto done;
	}

	/* verify address is aligned */
	if (sbsf->off & (sbsf->erase_size - 1)) {
	log_content(" sector erase: cmd:%#x needs align:%#x, but we got %#x\n",
	sbsf->cmd, sbsf->erase_size,
	sbsf->off);
	sbsf->status &= ~STAT_WEL;
	goto done;
	}

	log_content(" sector erase addr: %u, size: %u\n",
	sbsf->off, sbsf->erase_size);

	cnt = bytes - pos;
	if (tx)
	sandbox_spi_tristate(&tx[pos], cnt);
	pos += cnt;

	/*
	* TODO(vapier@gentoo.org): latch WIP in status, and
	* delay before clearing it ?
	*/
	ret = sandbox_erase_part(sbsf, sbsf->erase_size);
	sbsf->status &= ~STAT_WEL;
	if (ret) {
	log_content("sandbox_sf: Erase failed\n");
	goto done;
	}
	goto done;
	}
	default:
	log_content(" ??? no idea what to do ???\n");
	goto done;
	}
	}

	done:
	if (flags & SPI_XFER_END)
	sandbox_sf_cs_deactivate(dev);
	return pos == bytes ? 0 : -EIO;
	}

	int sandbox_sf_ofdata_to_platdata(struct udevice *dev)
	{
	struct sandbox_spi_flash_plat_data *pdata = dev_get_platdata(dev);

	pdata->filename = dev_read_string(dev, "sandbox,filename");
	pdata->device_name = dev_read_string(dev, "compatible");
	if (!pdata->filename \|\| !pdata->device_name) {
	debug("%s: Missing properties, filename=%s, device_name=%s\n",
	__func__, pdata->filename, pdata->device_name);
	return -EINVAL;
	}

	return 0;
	}

	static const struct dm_spi_emul_ops sandbox_sf_emul_ops = {
	.xfer = sandbox_sf_xfer,
	};

	#ifdef CONFIG_SPI_FLASH
	int sandbox_sf_bind_emul(struct sandbox_state *state, int busnum, int cs,
	struct udevice bus, ofnode node, const char spec)
	{
	struct udevice *emul;
	char name[20], *str;
	struct driver *drv;
	int ret;

	/* now the emulator */
	strncpy(name, spec, sizeof(name) - 6);
	name[sizeof(name) - 6] = '\0';
	strcat(name, "-emul");
	drv = lists_driver_lookup_name("sandbox_sf_emul");
	if (!drv) {
	puts("Cannot find sandbox_sf_emul driver\n");
	return -ENOENT;
	}
	str = strdup(name);
	if (!str)
	return -ENOMEM;
	ret = device_bind_ofnode(bus, drv, str, NULL, node, &emul);
	if (ret) {
	free(str);
	printf("Cannot create emul device for spec '%s' (err=%d)\n",
	spec, ret);
	return ret;
	}
	state->spi[busnum][cs].emul = emul;

	return 0;
	}

	void sandbox_sf_unbind_emul(struct sandbox_state *state, int busnum, int cs)
	{
	struct udevice *dev;

	dev = state->spi[busnum][cs].emul;
	device_remove(dev, DM_REMOVE_NORMAL);
	device_unbind(dev);
	state->spi[busnum][cs].emul = NULL;
	}

	int sandbox_spi_get_emul(struct sandbox_state *state,
	struct udevice bus, struct udevice slave,
	struct udevice **emulp)
	{
	struct sandbox_spi_info *info;
	int busnum = bus->seq;
	int cs = spi_chip_select(slave);
	int ret;

	info = &state->spi[busnum][cs];
	if (!info->emul) {
	/* Use the same device tree node as the SPI flash device */
	debug("%s: busnum=%u, cs=%u: binding SPI flash emulation: ",
	__func__, busnum, cs);
	ret = sandbox_sf_bind_emul(state, busnum, cs, bus,
	dev_ofnode(slave), slave->name);
	if (ret) {
	debug("failed (err=%d)\n", ret);
	return ret;
	}
	debug("OK\n");
	}
	*emulp = info->emul;

	return 0;
	}
	#endif

	static const struct udevice_id sandbox_sf_ids[] = {
	{ .compatible = "sandbox,spi-flash" },
	{ }
	};

	U_BOOT_DRIVER(sandbox_sf_emul) = {
	.name = "sandbox_sf_emul",
	.id = UCLASS_SPI_EMUL,
	.of_match = sandbox_sf_ids,
	.ofdata_to_platdata = sandbox_sf_ofdata_to_platdata,
	.probe = sandbox_sf_probe,
	.remove = sandbox_sf_remove,
	.priv_auto_alloc_size = sizeof(struct sandbox_spi_flash),
	.platdata_auto_alloc_size = sizeof(struct sandbox_spi_flash_plat_data),
	.ops = &sandbox_sf_emul_ops,
	};