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nfsmb.c revision 1.17
      1 /*	$NetBSD: nfsmb.c,v 1.17 2009/05/06 09:25:16 cegger Exp $	*/
      2 /*
      3  * Copyright (c) 2007 KIYOHARA Takashi
      4  * All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     17  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     18  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
     19  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     20  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     21  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
     23  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
     24  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     25  * POSSIBILITY OF SUCH DAMAGE.
     26  *
     27  */
     28 #include <sys/cdefs.h>
     29 __KERNEL_RCSID(0, "$NetBSD: nfsmb.c,v 1.17 2009/05/06 09:25:16 cegger Exp $");
     30 
     31 #include <sys/param.h>
     32 #include <sys/device.h>
     33 #include <sys/errno.h>
     34 #include <sys/kernel.h>
     35 #include <sys/rwlock.h>
     36 #include <sys/proc.h>
     37 
     38 #include <sys/bus.h>
     39 
     40 #include <dev/i2c/i2cvar.h>
     41 
     42 #include <dev/pci/pcivar.h>
     43 #include <dev/pci/pcireg.h>
     44 #include <dev/pci/pcidevs.h>
     45 
     46 #include <dev/pci/nfsmbreg.h>
     47 
     48 
     49 struct nfsmbc_attach_args {
     50 	int nfsmb_num;
     51 	bus_space_tag_t nfsmb_iot;
     52 	int nfsmb_addr;
     53 };
     54 
     55 struct nfsmb_softc;
     56 struct nfsmbc_softc {
     57 	device_t sc_dev;
     58 
     59 	pci_chipset_tag_t sc_pc;
     60 	pcitag_t sc_tag;
     61 	struct pci_attach_args *sc_pa;
     62 
     63 	bus_space_tag_t sc_iot;
     64 	struct device *sc_nfsmb[2];
     65 };
     66 
     67 struct nfsmb_softc {
     68 	device_t sc_dev;
     69 	int sc_num;
     70 	struct device *sc_nfsmbc;
     71 
     72 	bus_space_tag_t sc_iot;
     73 	bus_space_handle_t sc_ioh;
     74 
     75 	struct i2c_controller sc_i2c;	/* i2c controller info */
     76 	krwlock_t sc_rwlock;
     77 };
     78 
     79 
     80 static int nfsmbc_match(device_t, cfdata_t, void *);
     81 static void nfsmbc_attach(device_t, device_t, void *);
     82 static int nfsmbc_print(void *, const char *);
     83 
     84 static int nfsmb_match(device_t, cfdata_t, void *);
     85 static void nfsmb_attach(device_t, device_t, void *);
     86 static int nfsmb_acquire_bus(void *, int);
     87 static void nfsmb_release_bus(void *, int);
     88 static int nfsmb_exec(
     89     void *, i2c_op_t, i2c_addr_t, const void *, size_t, void *, size_t, int);
     90 static int nfsmb_check_done(struct nfsmb_softc *);
     91 static int
     92     nfsmb_send_1(struct nfsmb_softc *, uint8_t, i2c_addr_t, i2c_op_t, int);
     93 static int nfsmb_write_1(
     94     struct nfsmb_softc *, uint8_t, uint8_t, i2c_addr_t, i2c_op_t, int);
     95 static int nfsmb_write_2(
     96     struct nfsmb_softc *, uint8_t, uint16_t, i2c_addr_t, i2c_op_t, int);
     97 static int nfsmb_receive_1(struct nfsmb_softc *, i2c_addr_t, i2c_op_t, int);
     98 static int
     99     nfsmb_read_1(struct nfsmb_softc *, uint8_t, i2c_addr_t, i2c_op_t, int);
    100 static int
    101     nfsmb_read_2(struct nfsmb_softc *, uint8_t, i2c_addr_t, i2c_op_t, int);
    102 static int
    103     nfsmb_quick(struct nfsmb_softc *, i2c_addr_t, i2c_op_t, int);
    104 
    105 CFATTACH_DECL_NEW(nfsmbc, sizeof(struct nfsmbc_softc),
    106     nfsmbc_match, nfsmbc_attach, NULL, NULL);
    107 
    108 static int
    109 nfsmbc_match(device_t parent, cfdata_t match, void *aux)
    110 {
    111 	struct pci_attach_args *pa = aux;
    112 
    113 	if (PCI_VENDOR(pa->pa_id) == PCI_VENDOR_NVIDIA) {
    114 		switch (PCI_PRODUCT(pa->pa_id)) {
    115 		case PCI_PRODUCT_NVIDIA_NFORCE2_SMBUS:
    116 		case PCI_PRODUCT_NVIDIA_NFORCE2_400_SMBUS:
    117 		case PCI_PRODUCT_NVIDIA_NFORCE3_SMBUS:
    118 		case PCI_PRODUCT_NVIDIA_NFORCE3_250_SMBUS:
    119 		case PCI_PRODUCT_NVIDIA_NFORCE4_SMBUS:
    120 		case PCI_PRODUCT_NVIDIA_NFORCE430_SMBUS:
    121 		case PCI_PRODUCT_NVIDIA_MCP04_SMBUS:
    122 		case PCI_PRODUCT_NVIDIA_MCP55_SMB:
    123 		case PCI_PRODUCT_NVIDIA_MCP61_SMB:
    124 		case PCI_PRODUCT_NVIDIA_MCP65_SMB:
    125 		case PCI_PRODUCT_NVIDIA_MCP67_SMB:
    126 		case PCI_PRODUCT_NVIDIA_MCP73_SMB:
    127 			return 1;
    128 		}
    129 	}
    130 
    131 	return 0;
    132 }
    133 
    134 static void
    135 nfsmbc_attach(device_t parent, device_t self, void *aux)
    136 {
    137 	struct nfsmbc_softc *sc = device_private(self);
    138 	struct pci_attach_args *pa = aux;
    139 	struct nfsmbc_attach_args nfsmbca;
    140 	pcireg_t reg;
    141 	int baseregs[2];
    142 	char devinfo[256];
    143 
    144 	aprint_naive("\n");
    145 	pci_devinfo(pa->pa_id, pa->pa_class, 0, devinfo, sizeof(devinfo));
    146 	aprint_normal(": %s (rev. 0x%02x)\n", devinfo,
    147 	    PCI_REVISION(pa->pa_class));
    148 
    149 	sc->sc_dev = self;
    150 	sc->sc_pc = pa->pa_pc;
    151 	sc->sc_tag = pa->pa_tag;
    152 	sc->sc_pa = pa;
    153 	sc->sc_iot = pa->pa_iot;
    154 
    155 	nfsmbca.nfsmb_iot = sc->sc_iot;
    156 
    157 	switch (PCI_PRODUCT(pa->pa_id)) {
    158 	case PCI_PRODUCT_NVIDIA_NFORCE2_SMBUS:
    159 	case PCI_PRODUCT_NVIDIA_NFORCE2_400_SMBUS:
    160 	case PCI_PRODUCT_NVIDIA_NFORCE3_SMBUS:
    161 	case PCI_PRODUCT_NVIDIA_NFORCE3_250_SMBUS:
    162 	case PCI_PRODUCT_NVIDIA_NFORCE4_SMBUS:
    163 		baseregs[0] = NFORCE_OLD_SMB1;
    164 		baseregs[1] = NFORCE_OLD_SMB2;
    165 		break;
    166 	default:
    167 		baseregs[0] = NFORCE_SMB1;
    168 		baseregs[1] = NFORCE_SMB2;
    169 		break;
    170 	}
    171 
    172 	reg = pci_conf_read(pa->pa_pc, pa->pa_tag, baseregs[0]);
    173 	nfsmbca.nfsmb_num = 1;
    174 	nfsmbca.nfsmb_addr = NFORCE_SMBBASE(reg);
    175 	sc->sc_nfsmb[0] = config_found(sc->sc_dev, &nfsmbca, nfsmbc_print);
    176 
    177 	reg = pci_conf_read(pa->pa_pc, pa->pa_tag, baseregs[1]);
    178 	nfsmbca.nfsmb_num = 2;
    179 	nfsmbca.nfsmb_addr = NFORCE_SMBBASE(reg);
    180 	sc->sc_nfsmb[1] = config_found(sc->sc_dev, &nfsmbca, nfsmbc_print);
    181 
    182 	/* This driver is similar to an ISA bridge that doesn't
    183 	 * need any special handling. So registering NULL handlers
    184 	 * are sufficent. */
    185 	if (!pmf_device_register(self, NULL, NULL))
    186 		aprint_error_dev(self, "couldn't establish power handler\n");
    187 }
    188 
    189 static int
    190 nfsmbc_print(void *aux, const char *pnp)
    191 {
    192 	struct nfsmbc_attach_args *nfsmbcap = aux;
    193 
    194 	if (pnp)
    195 		aprint_normal("nfsmb SMBus %d at %s",
    196 		    nfsmbcap->nfsmb_num, pnp);
    197 	else
    198 		aprint_normal(" SMBus %d", nfsmbcap->nfsmb_num);
    199 	return UNCONF;
    200 }
    201 
    202 
    203 CFATTACH_DECL_NEW(nfsmb, sizeof(struct nfsmb_softc),
    204     nfsmb_match, nfsmb_attach, NULL, NULL);
    205 
    206 static int
    207 nfsmb_match(device_t parent, cfdata_t match, void *aux)
    208 {
    209 	struct nfsmbc_attach_args *nfsmbcap = aux;
    210 
    211 	if (nfsmbcap->nfsmb_num == 1 || nfsmbcap->nfsmb_num == 2)
    212 		return 1;
    213 	return 0;
    214 }
    215 
    216 static void
    217 nfsmb_attach(device_t parent, device_t self, void *aux)
    218 {
    219 	struct nfsmb_softc *sc = device_private(self);
    220 	struct nfsmbc_attach_args *nfsmbcap = aux;
    221 	struct i2cbus_attach_args iba;
    222 
    223 	aprint_naive("\n");
    224 	aprint_normal("\n");
    225 
    226 	sc->sc_dev = self;
    227 	sc->sc_nfsmbc = parent;
    228 	sc->sc_num = nfsmbcap->nfsmb_num;
    229 	sc->sc_iot = nfsmbcap->nfsmb_iot;
    230 
    231 	/* register with iic */
    232 	sc->sc_i2c.ic_cookie = sc;
    233 	sc->sc_i2c.ic_acquire_bus = nfsmb_acquire_bus;
    234 	sc->sc_i2c.ic_release_bus = nfsmb_release_bus;
    235 	sc->sc_i2c.ic_send_start = NULL;
    236 	sc->sc_i2c.ic_send_stop = NULL;
    237 	sc->sc_i2c.ic_initiate_xfer = NULL;
    238 	sc->sc_i2c.ic_read_byte = NULL;
    239 	sc->sc_i2c.ic_write_byte = NULL;
    240 	sc->sc_i2c.ic_exec = nfsmb_exec;
    241 
    242 	rw_init(&sc->sc_rwlock);
    243 
    244 	if (bus_space_map(sc->sc_iot, nfsmbcap->nfsmb_addr, NFORCE_SMBSIZE, 0,
    245 	    &sc->sc_ioh) != 0) {
    246 		aprint_error_dev(self, "failed to map SMBus space\n");
    247 		return;
    248 	}
    249 
    250 	iba.iba_type = I2C_TYPE_SMBUS;
    251 	iba.iba_tag = &sc->sc_i2c;
    252 	(void) config_found_ia(sc->sc_dev, "i2cbus", &iba, iicbus_print);
    253 
    254 	/* This driver is similar to an ISA bridge that doesn't
    255 	 * need any special handling. So registering NULL handlers
    256 	 * are sufficent. */
    257 	if (!pmf_device_register(self, NULL, NULL))
    258 		aprint_error_dev(self, "couldn't establish power handler\n");
    259 }
    260 
    261 static int
    262 nfsmb_acquire_bus(void *cookie, int flags)
    263 {
    264 	struct nfsmb_softc *sc = cookie;
    265 
    266 	rw_enter(&sc->sc_rwlock, RW_WRITER);
    267 	return 0;
    268 }
    269 
    270 static void
    271 nfsmb_release_bus(void *cookie, int flags)
    272 {
    273 	struct nfsmb_softc *sc = cookie;
    274 
    275 	rw_exit(&sc->sc_rwlock);
    276 }
    277 
    278 static int
    279 nfsmb_exec(void *cookie, i2c_op_t op, i2c_addr_t addr, const void *cmd,
    280 	   size_t cmdlen, void *vbuf, size_t buflen, int flags)
    281 {
    282 	struct nfsmb_softc *sc  = (struct nfsmb_softc *)cookie;
    283 	uint8_t *p = vbuf;
    284 	int rv;
    285 
    286 	if ((cmdlen == 0) && (buflen == 0)) {
    287 		return nfsmb_quick(sc, addr, op, flags);
    288 	}
    289 
    290 	if (I2C_OP_READ_P(op) && (cmdlen == 0) && (buflen == 1)) {
    291 		rv = nfsmb_receive_1(sc, addr, op, flags);
    292 		if (rv == -1)
    293 			return -1;
    294 		*p = (uint8_t)rv;
    295 		return 0;
    296 	}
    297 
    298 	if ((I2C_OP_READ_P(op)) && (cmdlen == 1) && (buflen == 1)) {
    299 		rv = nfsmb_read_1(sc, *(const uint8_t*)cmd, addr, op, flags);
    300 		if (rv == -1)
    301 			return -1;
    302 		*p = (uint8_t)rv;
    303 		return 0;
    304 	}
    305 
    306 	if ((I2C_OP_READ_P(op)) && (cmdlen == 1) && (buflen == 2)) {
    307 		rv = nfsmb_read_2(sc, *(const uint8_t*)cmd, addr, op, flags);
    308 		if (rv == -1)
    309 			return -1;
    310 		*(uint16_t *)p = (uint16_t)rv;
    311 		return 0;
    312 	}
    313 
    314 	if ((I2C_OP_WRITE_P(op)) && (cmdlen == 0) && (buflen == 1))
    315 		return nfsmb_send_1(sc, *(uint8_t*)vbuf, addr, op, flags);
    316 
    317 	if ((I2C_OP_WRITE_P(op)) && (cmdlen == 1) && (buflen == 1))
    318 		return nfsmb_write_1(sc, *(const uint8_t*)cmd, *(uint8_t*)vbuf,
    319 		    addr, op, flags);
    320 
    321 	if ((I2C_OP_WRITE_P(op)) && (cmdlen == 1) && (buflen == 2))
    322 		return nfsmb_write_2(sc,
    323 		    *(const uint8_t*)cmd, *((uint16_t *)vbuf), addr, op, flags);
    324 
    325 	return -1;
    326 }
    327 
    328 static int
    329 nfsmb_check_done(struct nfsmb_softc *sc)
    330 {
    331 	int us;
    332 	uint8_t stat;
    333 
    334 	us = 10 * 1000;	/* XXXX: wait maximum 10 msec */
    335 	do {
    336 		delay(10);
    337 		us -= 10;
    338 		if (us <= 0)
    339 			return -1;
    340 	} while (bus_space_read_1(sc->sc_iot, sc->sc_ioh,
    341 	    NFORCE_SMB_PROTOCOL) != 0);
    342 
    343 	stat = bus_space_read_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_STATUS);
    344 	if ((stat & NFORCE_SMB_STATUS_DONE) &&
    345 	    !(stat & NFORCE_SMB_STATUS_STATUS))
    346 		return 0;
    347 	return -1;
    348 }
    349 
    350 /* ARGSUSED */
    351 static int
    352 nfsmb_quick(struct nfsmb_softc *sc, i2c_addr_t addr, i2c_op_t op, int flags)
    353 {
    354 	uint8_t data;
    355 
    356 	/* write smbus slave address to register */
    357 	data = addr << 1;
    358 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_ADDRESS, data);
    359 
    360 	/* write smbus protocol to register */
    361 	data = I2C_OP_READ_P(op) | NFORCE_SMB_PROTOCOL_QUICK;
    362 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_PROTOCOL, data);
    363 
    364 	return nfsmb_check_done(sc);
    365 }
    366 
    367 /* ARGSUSED */
    368 static int
    369 nfsmb_send_1(struct nfsmb_softc *sc, uint8_t val, i2c_addr_t addr, i2c_op_t op,
    370 	     int flags)
    371 {
    372 	uint8_t data;
    373 
    374 	/* store cmd */
    375 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_COMMAND, val);
    376 
    377 	/* write smbus slave address to register */
    378 	data = addr << 1;
    379 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_ADDRESS, data);
    380 
    381 	/* write smbus protocol to register */
    382 	data = I2C_OP_READ_P(op) | NFORCE_SMB_PROTOCOL_BYTE;
    383 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_PROTOCOL, data);
    384 
    385 	return nfsmb_check_done(sc);
    386 }
    387 
    388 /* ARGSUSED */
    389 static int
    390 nfsmb_write_1(struct nfsmb_softc *sc, uint8_t cmd, uint8_t val, i2c_addr_t addr,
    391 	      i2c_op_t op, int flags)
    392 {
    393 	uint8_t data;
    394 
    395 	/* store cmd */
    396 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_COMMAND, cmd);
    397 
    398 	/* store data */
    399 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_DATA, val);
    400 
    401 	/* write smbus slave address to register */
    402 	data = addr << 1;
    403 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_ADDRESS, data);
    404 
    405 	/* write smbus protocol to register */
    406 	data = I2C_OP_READ_P(op) | NFORCE_SMB_PROTOCOL_BYTE_DATA;
    407 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_PROTOCOL, data);
    408 
    409 	return nfsmb_check_done(sc);
    410 }
    411 
    412 static int
    413 nfsmb_write_2(struct nfsmb_softc *sc, uint8_t cmd, uint16_t val,
    414 	      i2c_addr_t addr, i2c_op_t op, int flags)
    415 {
    416 	uint8_t data, low, high;
    417 
    418 	/* store cmd */
    419 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_COMMAND, cmd);
    420 
    421 	/* store data */
    422 	low = val;
    423 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_DATA, low);
    424 	high = val >> 8;
    425 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_DATA, high);
    426 
    427 	/* write smbus slave address to register */
    428 	data = addr << 1;
    429 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_ADDRESS, data);
    430 
    431 	/* write smbus protocol to register */
    432 	data = I2C_OP_READ_P(op) | NFORCE_SMB_PROTOCOL_WORD_DATA;
    433 	if (flags & I2C_F_PEC)
    434 		data |= NFORCE_SMB_PROTOCOL_PEC;
    435 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_PROTOCOL, data);
    436 
    437 	return nfsmb_check_done(sc);
    438 }
    439 
    440 /* ARGSUSED */
    441 static int
    442 nfsmb_receive_1(struct nfsmb_softc *sc, i2c_addr_t addr, i2c_op_t op, int flags)
    443 {
    444 	uint8_t data;
    445 
    446 	/* write smbus slave address to register */
    447 	data = addr << 1;
    448 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_ADDRESS, data);
    449 
    450 	/* write smbus protocol to register */
    451 	data = I2C_OP_READ_P(op) | NFORCE_SMB_PROTOCOL_BYTE;
    452 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_PROTOCOL, data);
    453 
    454 	/* check for errors */
    455 	if (nfsmb_check_done(sc) < 0)
    456 		return -1;
    457 
    458 	/* read data */
    459 	return bus_space_read_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_DATA);
    460 }
    461 
    462 /* ARGSUSED */
    463 static int
    464 nfsmb_read_1(struct nfsmb_softc *sc, uint8_t cmd, i2c_addr_t addr, i2c_op_t op,
    465 	     int flags)
    466 {
    467 	uint8_t data;
    468 
    469 	/* store cmd */
    470 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_COMMAND, cmd);
    471 
    472 	/* write smbus slave address to register */
    473 	data = addr << 1;
    474 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_ADDRESS, data);
    475 
    476 	/* write smbus protocol to register */
    477 	data = I2C_OP_READ_P(op) | NFORCE_SMB_PROTOCOL_BYTE_DATA;
    478 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_PROTOCOL, data);
    479 
    480 	/* check for errors */
    481 	if (nfsmb_check_done(sc) < 0)
    482 		return -1;
    483 
    484 	/* read data */
    485 	return bus_space_read_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_DATA);
    486 }
    487 
    488 static int
    489 nfsmb_read_2(struct nfsmb_softc *sc, uint8_t cmd, i2c_addr_t addr, i2c_op_t op,
    490 	     int flags)
    491 {
    492 	uint8_t data, low, high;
    493 
    494 	/* store cmd */
    495 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_COMMAND, cmd);
    496 
    497 	/* write smbus slave address to register */
    498 	data = addr << 1;
    499 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_ADDRESS, data);
    500 
    501 	/* write smbus protocol to register */
    502 	data = I2C_OP_READ_P(op) | NFORCE_SMB_PROTOCOL_BYTE_DATA;
    503 	if (flags & I2C_F_PEC)
    504 		data |= NFORCE_SMB_PROTOCOL_PEC;
    505 	bus_space_write_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_PROTOCOL, data);
    506 
    507 	/* check for errors */
    508 	if (nfsmb_check_done(sc) < 0)
    509 		return -1;
    510 
    511 	/* read data */
    512 	low = bus_space_read_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_DATA);
    513 	high = bus_space_read_1(sc->sc_iot, sc->sc_ioh, NFORCE_SMB_DATA);
    514 	return low | high << 8;
    515 }
    516