drivers/i2c/busses/i2c-au1550.c

   1 /*
   2  * i2c-au1550.c: SMBus (i2c) adapter for Alchemy PSC interface
   3  * Copyright (C) 2004 Embedded Edge, LLC <dan@embeddededge.com>
   4  *
   5  * 2.6 port by Matt Porter <mporter@kernel.crashing.org>
   6  *
   7  * The documentation describes this as an SMBus controller, but it doesn't
   8  * understand any of the SMBus protocol in hardware.  It's really an I2C
   9  * controller that could emulate most of the SMBus in software.
  10  *
  11  * This is just a skeleton adapter to use with the Au1550 PSC
  12  * algorithm.  It was developed for the Pb1550, but will work with
  13  * any Au1550 board that has a similar PSC configuration.
  14  *
  15  * This program is free software; you can redistribute it and/or
  16  * modify it under the terms of the GNU General Public License
  17  * as published by the Free Software Foundation; either version 2
  18  * of the License, or (at your option) any later version.
  19  *
  20  * This program is distributed in the hope that it will be useful,
  21  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  * GNU General Public License for more details.
  24  *
  25  * You should have received a copy of the GNU General Public License
  26  * along with this program; if not, write to the Free Software
  27  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  28  */
  29
  30 #include <linux/delay.h>
  31 #include <linux/kernel.h>
  32 #include <linux/module.h>
  33 #include <linux/platform_device.h>
  34 #include <linux/init.h>
  35 #include <linux/errno.h>
  36 #include <linux/i2c.h>
  37 #include <linux/slab.h>
  38
  39 #include <asm/mach-au1x00/au1xxx.h>
  40 #include <asm/mach-au1x00/au1xxx_psc.h>
  41
  42 struct i2c_au1550_data {
  43         u32     psc_base;
  44         int     xfer_timeout;
  45         int     ack_timeout;
  46         struct i2c_adapter adap;
  47         struct resource *ioarea;
  48 };
  49
  50 static int
  51 wait_xfer_done(struct i2c_au1550_data *adap)
  52 {
  53         u32     stat;
  54         int     i;
  55         volatile psc_smb_t      *sp;
  56
  57         sp = (volatile psc_smb_t *)(adap->psc_base);
  58
  59         /* Wait for Tx Buffer Empty
  60         */
  61         for (i = 0; i < adap->xfer_timeout; i++) {
  62                 stat = sp->psc_smbstat;
  63                 au_sync();
  64                 if ((stat & PSC_SMBSTAT_TE) != 0)
  65                         return 0;
  66
  67                 udelay(1);
  68         }
  69
  70         return -ETIMEDOUT;
  71 }
  72
  73 static int
  74 wait_ack(struct i2c_au1550_data *adap)
  75 {
  76         u32     stat;
  77         volatile psc_smb_t      *sp;
  78
  79         if (wait_xfer_done(adap))
  80                 return -ETIMEDOUT;
  81
  82         sp = (volatile psc_smb_t *)(adap->psc_base);
  83
  84         stat = sp->psc_smbevnt;
  85         au_sync();
  86
  87         if ((stat & (PSC_SMBEVNT_DN | PSC_SMBEVNT_AN | PSC_SMBEVNT_AL)) != 0)
  88                 return -ETIMEDOUT;
  89
  90         return 0;
  91 }
  92
  93 static int
  94 wait_master_done(struct i2c_au1550_data *adap)
  95 {
  96         u32     stat;
  97         int     i;
  98         volatile psc_smb_t      *sp;
  99
 100         sp = (volatile psc_smb_t *)(adap->psc_base);
 101
 102         /* Wait for Master Done.
 103         */
 104         for (i = 0; i < adap->xfer_timeout; i++) {
 105                 stat = sp->psc_smbevnt;
 106                 au_sync();
 107                 if ((stat & PSC_SMBEVNT_MD) != 0)
 108                         return 0;
 109                 udelay(1);
 110         }
 111
 112         return -ETIMEDOUT;
 113 }
 114
 115 static int
 116 do_address(struct i2c_au1550_data *adap, unsigned int addr, int rd, int q)
 117 {
 118         volatile psc_smb_t      *sp;
 119         u32                     stat;
 120
 121         sp = (volatile psc_smb_t *)(adap->psc_base);
 122
 123         /* Reset the FIFOs, clear events.
 124         */
 125         stat = sp->psc_smbstat;
 126         sp->psc_smbevnt = PSC_SMBEVNT_ALLCLR;
 127         au_sync();
 128
 129         if (!(stat & PSC_SMBSTAT_TE) || !(stat & PSC_SMBSTAT_RE)) {
 130                 sp->psc_smbpcr = PSC_SMBPCR_DC;
 131                 au_sync();
 132                 do {
 133                         stat = sp->psc_smbpcr;
 134                         au_sync();
 135                 } while ((stat & PSC_SMBPCR_DC) != 0);
 136                 udelay(50);
 137         }
 138
 139         /* Write out the i2c chip address and specify operation
 140         */
 141         addr <<= 1;
 142         if (rd)
 143                 addr |= 1;
 144
 145         /* zero-byte xfers stop immediately */
 146         if (q)
 147                 addr |= PSC_SMBTXRX_STP;
 148
 149         /* Put byte into fifo, start up master.
 150         */
 151         sp->psc_smbtxrx = addr;
 152         au_sync();
 153         sp->psc_smbpcr = PSC_SMBPCR_MS;
 154         au_sync();
 155         if (wait_ack(adap))
 156                 return -EIO;
 157         return (q) ? wait_master_done(adap) : 0;
 158 }
 159
 160 static u32
 161 wait_for_rx_byte(struct i2c_au1550_data *adap, u32 *ret_data)
 162 {
 163         int     j;
 164         u32     data, stat;
 165         volatile psc_smb_t      *sp;
 166
 167         if (wait_xfer_done(adap))
 168                 return -EIO;
 169
 170         sp = (volatile psc_smb_t *)(adap->psc_base);
 171
 172         j =  adap->xfer_timeout * 100;
 173         do {
 174                 j--;
 175                 if (j <= 0)
 176                         return -EIO;
 177
 178                 stat = sp->psc_smbstat;
 179                 au_sync();
 180                 if ((stat & PSC_SMBSTAT_RE) == 0)
 181                         j = 0;
 182                 else
 183                         udelay(1);
 184         } while (j > 0);
 185         data = sp->psc_smbtxrx;
 186         au_sync();
 187         *ret_data = data;
 188
 189         return 0;
 190 }
 191
 192 static int
 193 i2c_read(struct i2c_au1550_data *adap, unsigned char *buf,
 194                     unsigned int len)
 195 {
 196         int     i;
 197         u32     data;
 198         volatile psc_smb_t      *sp;
 199
 200         if (len == 0)
 201                 return 0;
 202
 203         /* A read is performed by stuffing the transmit fifo with
 204          * zero bytes for timing, waiting for bytes to appear in the
 205          * receive fifo, then reading the bytes.
 206          */
 207
 208         sp = (volatile psc_smb_t *)(adap->psc_base);
 209
 210         i = 0;
 211         while (i < (len-1)) {
 212                 sp->psc_smbtxrx = 0;
 213                 au_sync();
 214                 if (wait_for_rx_byte(adap, &data))
 215                         return -EIO;
 216
 217                 buf[i] = data;
 218                 i++;
 219         }
 220
 221         /* The last byte has to indicate transfer done.
 222         */
 223         sp->psc_smbtxrx = PSC_SMBTXRX_STP;
 224         au_sync();
 225         if (wait_master_done(adap))
 226                 return -EIO;
 227
 228         data = sp->psc_smbtxrx;
 229         au_sync();
 230         buf[i] = data;
 231         return 0;
 232 }
 233
 234 static int
 235 i2c_write(struct i2c_au1550_data *adap, unsigned char *buf,
 236                      unsigned int len)
 237 {
 238         int     i;
 239         u32     data;
 240         volatile psc_smb_t      *sp;
 241
 242         if (len == 0)
 243                 return 0;
 244
 245         sp = (volatile psc_smb_t *)(adap->psc_base);
 246
 247         i = 0;
 248         while (i < (len-1)) {
 249                 data = buf[i];
 250                 sp->psc_smbtxrx = data;
 251                 au_sync();
 252                 if (wait_ack(adap))
 253                         return -EIO;
 254                 i++;
 255         }
 256
 257         /* The last byte has to indicate transfer done.
 258         */
 259         data = buf[i];
 260         data |= PSC_SMBTXRX_STP;
 261         sp->psc_smbtxrx = data;
 262         au_sync();
 263         if (wait_master_done(adap))
 264                 return -EIO;
 265         return 0;
 266 }
 267
 268 static int
 269 au1550_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
 270 {
 271         struct i2c_au1550_data *adap = i2c_adap->algo_data;
 272         volatile psc_smb_t *sp = (volatile psc_smb_t *)adap->psc_base;
 273         struct i2c_msg *p;
 274         int i, err = 0;
 275
 276         sp->psc_ctrl = PSC_CTRL_ENABLE;
 277         au_sync();
 278
 279         for (i = 0; !err && i < num; i++) {
 280                 p = &msgs[i];
 281                 err = do_address(adap, p->addr, p->flags & I2C_M_RD,
 282                                  (p->len == 0));
 283                 if (err || !p->len)
 284                         continue;
 285                 if (p->flags & I2C_M_RD)
 286                         err = i2c_read(adap, p->buf, p->len);
 287                 else
 288                         err = i2c_write(adap, p->buf, p->len);
 289         }
 290
 291         /* Return the number of messages processed, or the error code.
 292         */
 293         if (err == 0)
 294                 err = num;
 295
 296         sp->psc_ctrl = PSC_CTRL_SUSPEND;
 297         au_sync();
 298
 299         return err;
 300 }
 301
 302 static u32
 303 au1550_func(struct i2c_adapter *adap)
 304 {
 305         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 306 }
 307
 308 static const struct i2c_algorithm au1550_algo = {
 309         .master_xfer    = au1550_xfer,
 310         .functionality  = au1550_func,
 311 };
 312
 313 static void i2c_au1550_setup(struct i2c_au1550_data *priv)
 314 {
 315         volatile psc_smb_t *sp = (volatile psc_smb_t *)priv->psc_base;
 316         u32 stat;
 317
 318         sp->psc_ctrl = PSC_CTRL_DISABLE;
 319         au_sync();
 320         sp->psc_sel = PSC_SEL_PS_SMBUSMODE;
 321         sp->psc_smbcfg = 0;
 322         au_sync();
 323         sp->psc_ctrl = PSC_CTRL_ENABLE;
 324         au_sync();
 325         do {
 326                 stat = sp->psc_smbstat;
 327                 au_sync();
 328         } while ((stat & PSC_SMBSTAT_SR) == 0);
 329
 330         sp->psc_smbcfg = (PSC_SMBCFG_RT_FIFO8 | PSC_SMBCFG_TT_FIFO8 |
 331                                 PSC_SMBCFG_DD_DISABLE);
 332
 333         /* Divide by 8 to get a 6.25 MHz clock.  The later protocol
 334          * timings are based on this clock.
 335          */
 336         sp->psc_smbcfg |= PSC_SMBCFG_SET_DIV(PSC_SMBCFG_DIV8);
 337         sp->psc_smbmsk = PSC_SMBMSK_ALLMASK;
 338         au_sync();
 339
 340         /* Set the protocol timer values.  See Table 71 in the
 341          * Au1550 Data Book for standard timing values.
 342          */
 343         sp->psc_smbtmr = PSC_SMBTMR_SET_TH(0) | PSC_SMBTMR_SET_PS(15) | \
 344                 PSC_SMBTMR_SET_PU(15) | PSC_SMBTMR_SET_SH(15) | \
 345                 PSC_SMBTMR_SET_SU(15) | PSC_SMBTMR_SET_CL(15) | \
 346                 PSC_SMBTMR_SET_CH(15);
 347         au_sync();
 348
 349         sp->psc_smbcfg |= PSC_SMBCFG_DE_ENABLE;
 350         do {
 351                 stat = sp->psc_smbstat;
 352                 au_sync();
 353         } while ((stat & PSC_SMBSTAT_SR) == 0);
 354
 355         sp->psc_ctrl = PSC_CTRL_SUSPEND;
 356         au_sync();
 357 }
 358
 359 static void i2c_au1550_disable(struct i2c_au1550_data *priv)
 360 {
 361         volatile psc_smb_t *sp = (volatile psc_smb_t *)priv->psc_base;
 362
 363         sp->psc_smbcfg = 0;
 364         sp->psc_ctrl = PSC_CTRL_DISABLE;
 365         au_sync();
 366 }
 367
 368 /*
 369  * registering functions to load algorithms at runtime
 370  * Prior to calling us, the 50MHz clock frequency and routing
 371  * must have been set up for the PSC indicated by the adapter.
 372  */
 373 static int __devinit
 374 i2c_au1550_probe(struct platform_device *pdev)
 375 {
 376         struct i2c_au1550_data *priv;
 377         struct resource *r;
 378         int ret;
 379
 380         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 381         if (!r) {
 382                 ret = -ENODEV;
 383                 goto out;
 384         }
 385
 386         priv = kzalloc(sizeof(struct i2c_au1550_data), GFP_KERNEL);
 387         if (!priv) {
 388                 ret = -ENOMEM;
 389                 goto out;
 390         }
 391
 392         priv->ioarea = request_mem_region(r->start, r->end - r->start + 1,
 393                                           pdev->name);
 394         if (!priv->ioarea) {
 395                 ret = -EBUSY;
 396                 goto out_mem;
 397         }
 398
 399         priv->psc_base = CKSEG1ADDR(r->start);
 400         priv->xfer_timeout = 200;
 401         priv->ack_timeout = 200;
 402
 403         priv->adap.nr = pdev->id;
 404         priv->adap.algo = &au1550_algo;
 405         priv->adap.algo_data = priv;
 406         priv->adap.dev.parent = &pdev->dev;
 407         strlcpy(priv->adap.name, "Au1xxx PSC I2C", sizeof(priv->adap.name));
 408
 409         /* Now, set up the PSC for SMBus PIO mode.
 410         */
 411         i2c_au1550_setup(priv);
 412
 413         ret = i2c_add_numbered_adapter(&priv->adap);
 414         if (ret == 0) {
 415                 platform_set_drvdata(pdev, priv);
 416                 return 0;
 417         }
 418
 419         i2c_au1550_disable(priv);
 420
 421         release_resource(priv->ioarea);
 422         kfree(priv->ioarea);
 423 out_mem:
 424         kfree(priv);
 425 out:
 426         return ret;
 427 }
 428
 429 static int __devexit
 430 i2c_au1550_remove(struct platform_device *pdev)
 431 {
 432         struct i2c_au1550_data *priv = platform_get_drvdata(pdev);
 433
 434         platform_set_drvdata(pdev, NULL);
 435         i2c_del_adapter(&priv->adap);
 436         i2c_au1550_disable(priv);
 437         release_resource(priv->ioarea);
 438         kfree(priv->ioarea);
 439         kfree(priv);
 440         return 0;
 441 }
 442
 443 #ifdef CONFIG_PM
 444 static int
 445 i2c_au1550_suspend(struct platform_device *pdev, pm_message_t state)
 446 {
 447         struct i2c_au1550_data *priv = platform_get_drvdata(pdev);
 448
 449         i2c_au1550_disable(priv);
 450
 451         return 0;
 452 }
 453
 454 static int
 455 i2c_au1550_resume(struct platform_device *pdev)
 456 {
 457         struct i2c_au1550_data *priv = platform_get_drvdata(pdev);
 458
 459         i2c_au1550_setup(priv);
 460
 461         return 0;
 462 }
 463 #else
 464 #define i2c_au1550_suspend      NULL
 465 #define i2c_au1550_resume       NULL
 466 #endif
 467
 468 static struct platform_driver au1xpsc_smbus_driver = {
 469         .driver = {
 470                 .name   = "au1xpsc_smbus",
 471                 .owner  = THIS_MODULE,
 472         },
 473         .probe          = i2c_au1550_probe,
 474         .remove         = __devexit_p(i2c_au1550_remove),
 475         .suspend        = i2c_au1550_suspend,
 476         .resume         = i2c_au1550_resume,
 477 };
 478
 479 static int __init
 480 i2c_au1550_init(void)
 481 {
 482         return platform_driver_register(&au1xpsc_smbus_driver);
 483 }
 484
 485 static void __exit
 486 i2c_au1550_exit(void)
 487 {
 488         platform_driver_unregister(&au1xpsc_smbus_driver);
 489 }
 490
 491 MODULE_AUTHOR("Dan Malek, Embedded Edge, LLC.");
 492 MODULE_DESCRIPTION("SMBus adapter Alchemy pb1550");
 493 MODULE_LICENSE("GPL");
 494 MODULE_ALIAS("platform:au1xpsc_smbus");
 495
 496 module_init (i2c_au1550_init);
 497 module_exit (i2c_au1550_exit);