selphy_print/backend_mitsu9550.c

/*
 *   Mitsubishi CP-9xxx Photo Printer Family CUPS backend
 *
 *   (c) 2014-2016 Solomon Peachy <pizza@shaftnet.org>
 *
 *   The latest version of this program can be found at:
 *
 *     http://git.shaftnet.org/cgit/selphy_print.git
 *
 *   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, write to the Free Software
 *   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 *          [http://www.gnu.org/licenses/gpl-3.0.html]
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <signal.h>

#define BACKEND mitsu9550_backend

#include "backend_common.h"

#define USB_VID_MITSU        0x06D3
#define USB_PID_MITSU_9500D  0x0393
#define USB_PID_MITSU_9000D  0x0394
#define USB_PID_MITSU_9000AM 0x0395
#define USB_PID_MITSU_9550D  0x03A1
#define USB_PID_MITSU_9550DS 0x03A5  // or DZ/DZS/DZU
#define USB_PID_MITSU_9600D  0x03A9
//#define USB_PID_MITSU_9600DS  XXXXXX
#define USB_PID_MITSU_9800D  0x03AD
#define USB_PID_MITSU_9800DS 0x03AE
#define USB_PID_MITSU_98__D  0x3B21
//#define USB_PID_MITSU_9810D   XXXXXX
//#define USB_PID_MITSU_9820DS  XXXXXX

/* Spool file structures */

/* Print parameters1 */
struct mitsu9550_hdr1 {
	uint8_t  cmd[4]; /* 1b 57 20 2e */
	uint8_t  unk[10]; /* 00 0a 10 00 [...] */
	uint16_t cols; /* BE */
	uint16_t rows; /* BE */
	uint8_t  matte;  /* CP9810 only. 01 for matte, 00 glossy */
	uint8_t  null[31];
} __attribute__((packed));

/* Print parameters2 */
struct mitsu9550_hdr2 {
	uint8_t  cmd[4]; /* 1b 57 21 2e */
	uint8_t  unk[24]; /* 00 80 00 22 08 03 00 [...] */
	uint16_t copies; /* BE, 1-680 */
	uint8_t  null[2];
	uint8_t  cut; /* 00 == normal, 83 == 2x6*2 */
	uint8_t  unkb[5];
	uint8_t  mode; /* 00 == fine, 80 == superfine */
	uint8_t  unkc[11]; /* 00 [...] 00 01 */
} __attribute__((packed));

/* Fine Deep selection (9550 only) */
struct mitsu9550_hdr3 {
	uint8_t  cmd[4]; /* 1b 57 22 2e */
	uint8_t  unk[7]; /* 00 40 00 [...] */
	uint8_t  mode2;  /* 00 == normal, 01 == finedeep */
	uint8_t  null[38];
} __attribute__((packed));

/* Error policy? */
struct mitsu9550_hdr4 {
	uint8_t  cmd[4]; /* 1b 57 26 2e */
	uint8_t  unk[46]; /* 00 70 00 00 00 00 00 00 01 01 00 [...] */
} __attribute__((packed));

/* Data plane header */
struct mitsu9550_plane {
	uint8_t  cmd[4]; /* 1b 5a 54 XX */  /* XX == 0x10 if 16bpp, 0x00 for 8bpp */
	uint16_t row_offset; /* BE, normally 0, where we start dumping data */
	uint16_t null;       /* ??? */
	uint16_t cols;       /* BE */
	uint16_t rows;       /* BE */
} __attribute__((packed));

struct mitsu9550_cmd {
	uint8_t cmd[4];
} __attribute__((packed));

/* Private data stucture */
struct mitsu9550_ctx {
	struct libusb_device_handle *dev;
	uint8_t endp_up;
	uint8_t endp_down;
	int type;
	int is_s;

	uint8_t *databuf;
	uint32_t datalen;

	uint16_t rows;
	uint16_t cols;
	uint32_t plane_len;

	uint16_t last_donor;
	uint16_t last_remain;
	int marker_reported;

	/* Parse headers separately */
	struct mitsu9550_hdr1 hdr1;
	int hdr1_present;
	struct mitsu9550_hdr2 hdr2;
	int hdr2_present;
	struct mitsu9550_hdr3 hdr3;
	int hdr3_present;
	struct mitsu9550_hdr4 hdr4;
	int hdr4_present;
};

/* Printer data structures */
struct mitsu9550_media {
	uint8_t  hdr[2];  /* 24 2e */
	uint8_t  unk[12];
	uint8_t  type;
	uint8_t  unka[13];
	uint16_t max;  /* BE, prints per media */
	uint8_t  unkb[2];
	uint16_t remain; /* BE, prints remaining */
	uint8_t  unkc[14];
} __attribute__((packed));

struct mitsu9550_status {
	uint8_t  hdr[2]; /* 30 2e */
	uint8_t  null[4];
	uint8_t  sts1; // MM
	uint8_t  nullb[1];
	uint16_t copies; // BE, NN
	uint8_t  sts2; // ZZ  (9600 only?)
	uint8_t  nullc[5];
	uint8_t  sts3; // QQ
	uint8_t  sts4; // RR
	uint8_t  sts5; // SS
	uint8_t  nulld[25];
	uint8_t  sts6; // TT
	uint8_t  sts7; // UU
	uint8_t  nulle[2];
} __attribute__((packed));

struct mitsu9550_status2 {
	uint8_t  hdr[2]; /* 21 2e */
	uint8_t  unk[39];
	uint16_t remain; /* BE, media remaining */
	uint8_t  unkb[4]; /* 0a 00 00 01 */
} __attribute__((packed));

#define CMDBUF_LEN   64
#define READBACK_LEN 128

#define QUERY_STATUS()	\
	do {\
		struct mitsu9550_status *sts = (struct mitsu9550_status*) rdbuf;\
		/* struct mitsu9550_status2 *sts2 = (struct mitsu9550_status2*) rdbuf; */ \
		struct mitsu9550_media *media = (struct mitsu9550_media *) rdbuf; \
		uint16_t donor, remain;	\
		/* media */ \
		ret = mitsu9550_get_status(ctx, rdbuf, 0, 0, 1); \
		if (ret < 0) \
			return CUPS_BACKEND_FAILED; \
		\
		/* Tell CUPS about the consumables we report */ \
		if (!ctx->marker_reported) { \
			ctx->marker_reported = 1; \
			ATTR("marker-colors=#00FFFF#FF00FF#FFFF00\n");	\
			ATTR("marker-high-levels=100\n"); \
			ATTR("marker-low-levels=10\n");	\
			ATTR("marker-names='%s'\n", mitsu9550_media_types(media->type, ctx->is_s)); \
			ATTR("marker-types=ribbonWax\n"); \
		} \
		\
		/* Sanity-check media response */ \
		if (media->remain == 0 || media->max == 0) { \
			ERROR("Printer out of media!\n"); \
			ATTR("marker-levels=%d\n", 0); \
			return CUPS_BACKEND_HOLD; \
		} \
		remain = be16_to_cpu(media->remain); \
		donor = be16_to_cpu(media->max); \
		donor = remain/donor; \
		if (donor != ctx->last_donor) { \
			ctx->last_donor = donor; \
			ATTR("marker-levels=%u\n", donor); \
		} \
		if (remain != ctx->last_remain) { \
			ctx->last_remain = remain; \
			ATTR("marker-message=\"%u prints remaining on '%s' ribbon\"\n", remain, mitsu9550_media_types(media->type, ctx->is_s)); \
		} \
		if (validate_media(ctx->type, media->type, ctx->cols, ctx->rows)) { \
			ERROR("Incorrect media (%u) type for printjob (%ux%u)!\n", media->type, ctx->cols, ctx->rows); \
			return CUPS_BACKEND_HOLD; \
		} \
		/* status2 */ \
		ret = mitsu9550_get_status(ctx, rdbuf, 0, 1, 0); \
		if (ret < 0) \
			return CUPS_BACKEND_FAILED; \
		/* status */ \
		ret = mitsu9550_get_status(ctx, rdbuf, 1, 0, 0); \
		if (ret < 0) \
			return CUPS_BACKEND_FAILED; \
		\
		/* Make sure we're idle */ \
		if (sts->sts5 != 0) {  /* Printer ready for another job */ \
			sleep(1); \
			goto top; \
		} \
		/* Check for known errors */ \
		if (sts->sts2 != 0) {  \
			ERROR("Printer cover open!\n");	\
			return CUPS_BACKEND_STOP; \
		} \
	} while (0);

static void *mitsu9550_init(void)
{
	struct mitsu9550_ctx *ctx = malloc(sizeof(struct mitsu9550_ctx));
	if (!ctx) {
		ERROR("Memory Allocation Failure!\n");
		return NULL;
	}
	memset(ctx, 0, sizeof(struct mitsu9550_ctx));

	return ctx;
}

static void mitsu9550_attach(void *vctx, struct libusb_device_handle *dev,
			    uint8_t endp_up, uint8_t endp_down, uint8_t jobid)
{
	struct mitsu9550_ctx *ctx = vctx;
	struct libusb_device *device;
	struct libusb_device_descriptor desc;

	UNUSED(jobid);

	ctx->dev = dev;
	ctx->endp_up = endp_up;
	ctx->endp_down = endp_down;

	device = libusb_get_device(dev);
	libusb_get_device_descriptor(device, &desc);

	ctx->type = lookup_printer_type(&mitsu9550_backend,
					desc.idVendor, desc.idProduct);

	if (ctx->type == P_MITSU_9550S ||
	    ctx->type == P_MITSU_9800S)
		ctx->is_s = 1;

	ctx->last_donor = ctx->last_remain = 65535;
}


static void mitsu9550_teardown(void *vctx) {
	struct mitsu9550_ctx *ctx = vctx;

	if (!ctx)
		return;

	if (ctx->databuf)
		free(ctx->databuf);
	free(ctx);
}

static int mitsu9550_read_parse(void *vctx, int data_fd) {
	struct mitsu9550_ctx *ctx = vctx;
	uint8_t buf[sizeof(struct mitsu9550_hdr1)];
	int remain, i;
	uint32_t planelen = 0;

	if (!ctx)
		return CUPS_BACKEND_FAILED;

	if (ctx->databuf) {
		free(ctx->databuf);
		ctx->databuf = NULL;
	}

	ctx->hdr1_present = 0;
	ctx->hdr2_present = 0;
	ctx->hdr3_present = 0;
	ctx->hdr4_present = 0;

top:
	/* Read in initial header */
	remain = sizeof(buf);
	while (remain > 0) {
		i = read(data_fd, buf + sizeof(buf) - remain, remain);
		if (i == 0)
			return CUPS_BACKEND_CANCEL;
		if (i < 0)
			return CUPS_BACKEND_CANCEL;
		remain -= i;
	}

	/* Sanity check */
	if (buf[0] != 0x1b || buf[1] != 0x57 || buf[3] != 0x2e) {
		if (!ctx->hdr1_present || !ctx->hdr2_present) {
			ERROR("Unrecognized data format!\n");
			return CUPS_BACKEND_CANCEL;
		} else if (buf[0] == 0x1b && buf[1] == 0x5a &&
			   buf[2] == 0x54) {

			/* We're in the data portion now */
			if (buf[3] == 0x10)
				planelen *= 2;

			goto hdr_done;
		} else {
			ERROR("Unrecognized data block!\n");
			return CUPS_BACKEND_CANCEL;
		}
	}

	switch(buf[2]) {
	case 0x20: /* header 1 */
		memcpy(&ctx->hdr1, buf, sizeof(ctx->hdr1));
		ctx->hdr1_present = 1;

		/* Work out printjob size */
		ctx->rows = be16_to_cpu(ctx->hdr1.rows);
		ctx->cols = be16_to_cpu(ctx->hdr1.cols);
		planelen = ctx->rows * ctx->cols;

		break;
	case 0x21: /* header 2 */
		memcpy(&ctx->hdr2, buf, sizeof(ctx->hdr2));
		ctx->hdr2_present = 1;
		break;
	case 0x22: /* header 3 */
		memcpy(&ctx->hdr3, buf, sizeof(ctx->hdr3));
		ctx->hdr3_present = 1;
		break;
	case 0x26: /* header 4 */
		memcpy(&ctx->hdr4, buf, sizeof(ctx->hdr4));
		ctx->hdr4_present = 1;
		break;
	default:
		ERROR("Unrecognized header format (%02x)!\n", buf[2]);
		return CUPS_BACKEND_CANCEL;
	}

	/* Read in the next chunk */
	goto top;

hdr_done:

	/* We have three planes and the final terminator to read */
	remain = 3 * (planelen + sizeof(struct mitsu9550_plane)) + sizeof(struct mitsu9550_cmd);

	/* Mitsu9600 windows spool uses more, smaller blocks, but plane data is the same */
	if (ctx->type == P_MITSU_9600) {
		remain += 128 * sizeof(struct mitsu9550_plane); /* 39 extra seen on 4x6" */
	}

	/* Don't forget the matte plane! */
	if (ctx->hdr1.matte) {
		remain += planelen + sizeof(struct mitsu9550_plane) + sizeof(struct mitsu9550_cmd);
	}

	/* 9550S/9800S doesn't typically sent over hdr4! */
	if (ctx->type == P_MITSU_9550S ||
	    ctx->type == P_MITSU_9800S) {
		/* XXX Has to do with error policy, but not sure what.
		   Mitsu9550-S/9800-S will set this based on a command,
		   but it's not part of the standard job spool */
		ctx->hdr4_present = 0;
	}

	/* Allocate buffer for the payload */
	ctx->datalen = 0;
	ctx->databuf = malloc(remain);
	if (!ctx->databuf) {
		ERROR("Memory allocation failure!\n");
		return CUPS_BACKEND_FAILED;
	}

	/* Load up the data blocks.*/
	while(1) {
		/* Note that 'buf' needs to be already filled here! */
		struct mitsu9550_plane *plane = (struct mitsu9550_plane *)buf;

		/* Sanity check header... */
		if (plane->cmd[0] != 0x1b ||
		    plane->cmd[1] != 0x5a ||
		    plane->cmd[2] != 0x54) {
			ERROR("Unexpected data read, aborting job\n");
			return CUPS_BACKEND_CANCEL;
		}

		/* Work out the length of this block */
		planelen = be16_to_cpu(plane->rows) * be16_to_cpu(plane->cols);
		if (plane->cmd[3] == 0x10)
			planelen *= 2;

		/* Copy plane header into buffer */
		memcpy(ctx->databuf + ctx->datalen, buf, sizeof(buf));
		ctx->datalen += sizeof(buf);
		planelen -= sizeof(buf) - sizeof(struct mitsu9550_plane);

		/* Read in the spool data */
		while(planelen > 0) {
			i = read(data_fd, ctx->databuf + ctx->datalen, planelen);
			if (i == 0)
				return CUPS_BACKEND_CANCEL;
			if (i < 0)
				return CUPS_BACKEND_CANCEL;
			ctx->datalen += i;
			planelen -= i;
		}

		/* Try to read in the next chunk.  It will be one of:
		    - Additional block header (12B)
		    - Job footer (4B)
		*/
		i = read(data_fd, buf, 4);
		if (i == 0)
			return CUPS_BACKEND_CANCEL;
		if (i < 0)
			return CUPS_BACKEND_CANCEL;

		/* Is this a "job end" marker? */
		if (plane->cmd[0] != 0x1b ||
		    plane->cmd[1] != 0x5a ||
		    plane->cmd[2] != 0x54) {
			/* store it in the buffer */
			memcpy(ctx->databuf + ctx->datalen, buf, 4);
			ctx->datalen += 4;

			/* Unless we have a matte plane following, we're done */
			if (!ctx->hdr1.matte)
				break;
			planelen = sizeof(buf);
		} else {
			/* It's part of a block header, mark what we've read */
			planelen = sizeof(buf) - 4;
		}

		/* Read in the rest of the header */
		while (planelen > 0) {
			i = read(data_fd, buf + sizeof(buf) - planelen, planelen);
			if (i == 0)
				return CUPS_BACKEND_CANCEL;
			if (i < 0)
				return CUPS_BACKEND_CANCEL;
			planelen -= i;
		}
	}

	/* Disable matte if the printer doesn't support it */
	if (ctx->hdr1.matte && ctx->type != P_MITSU_9810) {
		WARNING("Matte not supported on this printer, disabling\n");
		ctx->hdr1.matte = 0;
	}

	return CUPS_BACKEND_OK;
}

static int mitsu9550_get_status(struct mitsu9550_ctx *ctx, uint8_t *resp, int status, int status2, int media)
{
	struct mitsu9550_cmd cmd;
	int num, ret;

	/* Send Printer Query */
	cmd.cmd[0] = 0x1b;
	cmd.cmd[1] = 0x56;
	if (status)
		cmd.cmd[2] = 0x30;
	else if (status2)
		cmd.cmd[2] = 0x21;
	else if (media)
		cmd.cmd[2] = 0x24;
	cmd.cmd[3] = 0x00;
	if ((ret = send_data(ctx->dev, ctx->endp_down,
			     (uint8_t*) &cmd, sizeof(cmd))))
		return ret;
	ret = read_data(ctx->dev, ctx->endp_up,
			resp, sizeof(struct mitsu9550_status), &num);

	if (ret < 0)
		return ret;
	if (num != sizeof(struct mitsu9550_status)) {
		ERROR("Short Read! (%d/%d)\n", num, (int)sizeof(struct mitsu9550_status));
		return 4;
	}

	return 0;
}

static char *mitsu9550_media_types(uint8_t type, uint8_t is_s)
{
	if (is_s) {
		switch (type & 0xf) { /* values can be 0x0? or 0x4? */
		case 0x02:
			return "CK9015 (4x6)";
		case 0x04:
			return "CK9318 (5x7)";
		case 0x05:
			return "CK9523 (6x9)";
		default:
			return "Unknown";
		}
		return NULL;
	}
	
	switch (type & 0xf) { /* values can be 0x0? or 0x4? */
	case 0x01:
		return "CK9035 (3.5x5)";
	case 0x02:
		return "CK9046 (4x6)";
	case 0x03:
		return "CK9046PST (4x6)";
	case 0x04:
		return "CK9057 (5x7)";
	case 0x05:
		return "CK9069 (6x9)";
	case 0x06:
		return "CK9068 (6x8)";
	default:
		return "Unknown";
	}
	return NULL;
}

static int validate_media(int type, int media, int cols, int rows)
{
	switch(type) {
	case P_MITSU_9550:
		switch(media & 0xf) {
		case 0x01: /* 3.5x5 */
			if (cols != 1812 && rows != 1240)
				return 1;
			break;
		case 0x02: /* 4x6 */
		case 0x03: /* 4x6 postcard */ 
			if (cols != 2152)
				return 1;
			if (rows != 1416 && rows != 1184 && rows != 1240)
				return 1;
			break;
		case 0x04: /* 5x7 */
			if (cols != 1812)
				return 1;
			if (rows != 1240 && rows != 2452)
				return 1;
			break;
		case 0x05: /* 6x9 */
			if (cols != 2152)
				return 1;
			if (rows != 1416 && rows != 2792 &&
			    rows != 2956 && rows != 3146)
				return 1;
			break;
		case 0x06: /* V (6x8??) */
			if (cols != 2152)
				return 1;
			if (rows != 1416 && rows != 2792)
				return 1;
			break;
		default: /* Unknown */
			WARNING("Unknown media type %02x\n", media);
			break;
		}
		break;
	case P_MITSU_9550S:
		switch(media & 0xf) {
		case 0x02: /* 4x6 */
		case 0x03: /* 4x6 postcard */
			if (cols != 2152)
				return 1;
			if (rows != 1416 && rows != 1184 && rows != 1240)
				return 1;
			break;
		case 0x04: /* 5x7 */
			if (cols != 1812 && rows != 2452)
				return 1;
			break;
		case 0x05: /* 6x9 */
			if (cols != 2152)
				return 1;
			if (rows != 1416 && rows != 2792 &&
			    rows != 2956 && rows != 3146)
				return 1;
			break;
		case 0x06: /* V (6x8??) */
			if (cols != 2152)
				return 1;
			if (rows != 1416 && rows != 2792)
				return 1;
			break;
		default: /* Unknown */
			WARNING("Unknown media type %02x\n", media);
			break;
		}
		break;
	case P_MITSU_9600: // XXX 9600S doesn't support 5" media at all!
		switch(media & 0xf) {
		case 0x01: /* 3.5x5 */
			if (cols == 1572) {
				if (rows == 1076)
					break;
			} else if (cols == 3144) {
				if (rows == 2152)
					break;
			}
			return 1;
		case 0x02: /* 4x6 */
		case 0x03: /* 4x6 postcard */
			if (cols == 1868) {
				if (rows == 1228)
					break;
			} else if (cols == 3736) {
				if (rows == 2458)
					break;
			}
			return 1;
		case 0x04: /* 5x7 */
			if (cols == 1572) {
				if (rows == 1076 || rows == 2128)
					break;
			} else if (cols == 3144) {
				if (rows == 2152 || rows == 4256)
					break;
			}
			return 1;
		case 0x05: /* 6x9 */
			if (cols == 1868) {
				if (rows == 1228 || rows == 2442 || rows == 2564 || rows == 2730)
					break;
			} else if (cols == 3736) {
				if (rows == 2458 || rows == 4846 || rows == 5130 || rows == 5462)
					break;
			}
			return 1;
		case 0x06: /* V (6x8??) */
			if (cols == 1868) {
				if (rows == 1228 || rows == 2442)
					break;
			} else if (cols == 3736) {
				if (rows == 2458 || rows == 4846)
					break;
			}
			return 1;
		default: /* Unknown */
			WARNING("Unknown media type %02x\n", media);
			break;
		}
		break;
	case P_MITSU_9800:
	case P_MITSU_9810: // XXX and don't forget the 9820S
		switch(media & 0xf) {
		case 0x01: /* 3.5x5 */
			if (cols != 1572 && rows != 1076)
				return 1;
			break;
		case 0x02: /* 4x6 */
		case 0x03: /* 4x6 postcard */
			if (cols != 1868 && rows != 1228)
				return 1;
			break;
		case 0x04: /* 5x7 */
			if (cols != 1572 && rows != 2128)
				return 1;
			break;
		case 0x05: /* 6x9 */
			if (cols != 1868)
				return 1;
			if (rows != 1228 && rows != 2442 &&
			    rows != 2564 && rows != 2730)
				return 1;
			break;
		case 0x06: /* V (6x8??) */
			if (cols != 1868)
				return 1;
			if (rows != 1228 && rows != 2442)
				return 1;
			break;
		default: /* Unknown */
			WARNING("Unknown media type %02x\n", media);
			break;
		}
		break;
	case P_MITSU_9800S:
		switch(media & 0xf) {
		case 0x02: /* 4x6 */
		case 0x03: /* 4x6 postcard */ 
			if (cols != 1868 && rows != 1228)
				return 1;
			break;
		case 0x04: /* 5x7 */
			if (cols != 1572 && rows != 2128)
				return 1;
			break;
		case 0x05: /* 6x9 */
			if (cols != 1868)
				return 1;
			if (rows != 1228 && rows != 2442 &&
			    rows != 2564 && rows != 2730)
				return 1;
			break;
		case 0x06: /* V (6x8??) */
			if (cols != 1868)
				return 1;
			if (rows != 1228 && rows != 2442)
				return 1;
			break;
		default: /* Unknown */
			WARNING("Unknown media type %02x\n", media);
			break;
		}
		break;
	default:
		WARNING("Unknown printer type %d\n", type);
		break;
	}
	return 0;
}

static int mitsu9550_main_loop(void *vctx, int copies) {
	struct mitsu9550_ctx *ctx = vctx;
	struct mitsu9550_cmd cmd;
	uint8_t rdbuf[READBACK_LEN];
	uint8_t *ptr;

	int ret;

	if (!ctx)
		return CUPS_BACKEND_FAILED;

	/* Update printjob header to reflect number of requested copies */
	ctx->hdr2.copies = cpu_to_be16(copies);

	/* Okay, let's do this thing */
	ptr = ctx->databuf;

top:
	if (ctx->is_s) {
		int num;

		/* Send "unknown 1" command */
		cmd.cmd[0] = 0x1b;
		cmd.cmd[1] = 0x53;
		cmd.cmd[2] = 0xc5;
		cmd.cmd[3] = 0x9d;
		if ((ret = send_data(ctx->dev, ctx->endp_down,
				     (uint8_t*) &cmd, sizeof(cmd))))
			return CUPS_BACKEND_FAILED;

		/* Send "unknown 2" command */
		cmd.cmd[0] = 0x1b;
		cmd.cmd[1] = 0x4b;
		cmd.cmd[2] = 0x7f;
		cmd.cmd[3] = 0x00;
		if ((ret = send_data(ctx->dev, ctx->endp_down,
				     (uint8_t*) &cmd, sizeof(cmd))))
			return CUPS_BACKEND_FAILED;

		ret = read_data(ctx->dev, ctx->endp_up,
				rdbuf, READBACK_LEN, &num);
		if (ret < 0)
			return CUPS_BACKEND_FAILED;
		// seen so far: eb 4b 7f 00  02 00 5e
	}