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/au1000.h>
  40 #include <asm/mach-au1x00/au1xxx_psc.h>
  41
  42 #define PSC_SEL         0x00
  43 #define PSC_CTRL        0x04
  44 #define PSC_SMBCFG      0x08
  45 #define PSC_SMBMSK      0x0C
  46 #define PSC_SMBPCR      0x10
  47 #define PSC_SMBSTAT     0x14
  48 #define PSC_SMBEVNT     0x18
  49 #define PSC_SMBTXRX     0x1C
  50 #define PSC_SMBTMR      0x20
  51
  52 struct i2c_au1550_data {
  53         void __iomem *psc_base;
  54         int     xfer_timeout;
  55         struct i2c_adapter adap;
  56         struct resource *ioarea;
  57 };
  58
  59 static inline void WR(struct i2c_au1550_data *a, int r, unsigned long v)
  60 {
  61         __raw_writel(v, a->psc_base + r);
  62         wmb();
  63 }
  64
  65 static inline unsigned long RD(struct i2c_au1550_data *a, int r)
  66 {
  67         return __raw_readl(a->psc_base + r);
  68 }
  69
  70 static int wait_xfer_done(struct i2c_au1550_data *adap)
  71 {
  72         int i;
  73
  74         /* Wait for Tx Buffer Empty */
  75         for (i = 0; i < adap->xfer_timeout; i++) {
  76                 if (RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_TE)
  77                         return 0;
  78
  79                 udelay(1);
  80         }
  81
  82         return -ETIMEDOUT;
  83 }
  84
  85 static int wait_ack(struct i2c_au1550_data *adap)
  86 {
  87         unsigned long stat;
  88
  89         if (wait_xfer_done(adap))
  90                 return -ETIMEDOUT;
  91
  92         stat = RD(adap, PSC_SMBEVNT);
  93         if ((stat & (PSC_SMBEVNT_DN | PSC_SMBEVNT_AN | PSC_SMBEVNT_AL)) != 0)
  94                 return -ETIMEDOUT;
  95
  96         return 0;
  97 }
  98
  99 static int wait_master_done(struct i2c_au1550_data *adap)
 100 {
 101         int i;
 102
 103         /* Wait for Master Done. */
 104         for (i = 0; i < 2 * adap->xfer_timeout; i++) {
 105                 if ((RD(adap, PSC_SMBEVNT) & PSC_SMBEVNT_MD) != 0)
 106                         return 0;
 107                 udelay(1);
 108         }
 109
 110         return -ETIMEDOUT;
 111 }
 112
 113 static int
 114 do_address(struct i2c_au1550_data *adap, unsigned int addr, int rd, int q)
 115 {
 116         unsigned long stat;
 117
 118         /* Reset the FIFOs, clear events. */
 119         stat = RD(adap, PSC_SMBSTAT);
 120         WR(adap, PSC_SMBEVNT, PSC_SMBEVNT_ALLCLR);
 121
 122         if (!(stat & PSC_SMBSTAT_TE) || !(stat & PSC_SMBSTAT_RE)) {
 123                 WR(adap, PSC_SMBPCR, PSC_SMBPCR_DC);
 124                 while ((RD(adap, PSC_SMBPCR) & PSC_SMBPCR_DC) != 0)
 125                         cpu_relax();
 126                 udelay(50);
 127         }
 128
 129         /* Write out the i2c chip address and specify operation */
 130         addr <<= 1;
 131         if (rd)
 132                 addr |= 1;
 133
 134         /* zero-byte xfers stop immediately */
 135         if (q)
 136                 addr |= PSC_SMBTXRX_STP;
 137
 138         /* Put byte into fifo, start up master. */
 139         WR(adap, PSC_SMBTXRX, addr);
 140         WR(adap, PSC_SMBPCR, PSC_SMBPCR_MS);
 141         if (wait_ack(adap))
 142                 return -EIO;
 143         return (q) ? wait_master_done(adap) : 0;
 144 }
 145
 146 static int wait_for_rx_byte(struct i2c_au1550_data *adap, unsigned char *out)
 147 {
 148         int j;
 149
 150         if (wait_xfer_done(adap))
 151                 return -EIO;
 152
 153         j =  adap->xfer_timeout * 100;
 154         do {
 155                 j--;
 156                 if (j <= 0)
 157                         return -EIO;
 158
 159                 if ((RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_RE) == 0)
 160                         j = 0;
 161                 else
 162                         udelay(1);
 163         } while (j > 0);
 164
 165         *out = RD(adap, PSC_SMBTXRX);
 166
 167         return 0;
 168 }
 169
 170 static int i2c_read(struct i2c_au1550_data *adap, unsigned char *buf,
 171                     unsigned int len)
 172 {
 173         int i;
 174
 175         if (len == 0)
 176                 return 0;
 177
 178         /* A read is performed by stuffing the transmit fifo with
 179          * zero bytes for timing, waiting for bytes to appear in the
 180          * receive fifo, then reading the bytes.
 181          */
 182         i = 0;
 183         while (i < (len - 1)) {
 184                 WR(adap, PSC_SMBTXRX, 0);
 185                 if (wait_for_rx_byte(adap, &buf[i]))
 186                         return -EIO;
 187
 188                 i++;
 189         }
 190
 191         /* The last byte has to indicate transfer done. */
 192         WR(adap, PSC_SMBTXRX, PSC_SMBTXRX_STP);
 193         if (wait_master_done(adap))
 194                 return -EIO;
 195
 196         buf[i] = (unsigned char)(RD(adap, PSC_SMBTXRX) & 0xff);
 197         return 0;
 198 }
 199
 200 static int i2c_write(struct i2c_au1550_data *adap, unsigned char *buf,
 201                      unsigned int len)
 202 {
 203         int i;
 204         unsigned long data;
 205
 206         if (len == 0)
 207                 return 0;
 208
 209         i = 0;
 210         while (i < (len-1)) {
 211                 data = buf[i];
 212                 WR(adap, PSC_SMBTXRX, data);
 213                 if (wait_ack(adap))
 214                         return -EIO;
 215                 i++;
 216         }
 217
 218         /* The last byte has to indicate transfer done. */
 219         data = buf[i];
 220         data |= PSC_SMBTXRX_STP;
 221         WR(adap, PSC_SMBTXRX, data);
 222         if (wait_master_done(adap))
 223                 return -EIO;
 224         return 0;
 225 }
 226
 227 static int
 228 au1550_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
 229 {
 230         struct i2c_au1550_data *adap = i2c_adap->algo_data;
 231         struct i2c_msg *p;
 232         int i, err = 0;
 233
 234         WR(adap, PSC_CTRL, PSC_CTRL_ENABLE);
 235
 236         for (i = 0; !err && i < num; i++) {
 237                 p = &msgs[i];
 238                 err = do_address(adap, p->addr, p->flags & I2C_M_RD,
 239                                  (p->len == 0));
 240                 if (err || !p->len)
 241                         continue;
 242                 if (p->flags & I2C_M_RD)
 243                         err = i2c_read(adap, p->buf, p->len);
 244                 else
 245                         err = i2c_write(adap, p->buf, p->len);
 246         }
 247
 248         /* Return the number of messages processed, or the error code.
 249         */
 250         if (err == 0)
 251                 err = num;
 252
 253         WR(adap, PSC_CTRL, PSC_CTRL_SUSPEND);
 254
 255         return err;
 256 }
 257
 258 static u32 au1550_func(struct i2c_adapter *adap)
 259 {
 260         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 261 }
 262
 263 static const struct i2c_algorithm au1550_algo = {
 264         .master_xfer    = au1550_xfer,
 265         .functionality  = au1550_func,
 266 };
 267
 268 static void i2c_au1550_setup(struct i2c_au1550_data *priv)
 269 {
 270         unsigned long cfg;
 271
 272         WR(priv, PSC_CTRL, PSC_CTRL_DISABLE);
 273         WR(priv, PSC_SEL, PSC_SEL_PS_SMBUSMODE);
 274         WR(priv, PSC_SMBCFG, 0);
 275         WR(priv, PSC_CTRL, PSC_CTRL_ENABLE);
 276         while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0)
 277                 cpu_relax();
 278
 279         cfg = PSC_SMBCFG_RT_FIFO8 | PSC_SMBCFG_TT_FIFO8 | PSC_SMBCFG_DD_DISABLE;
 280         WR(priv, PSC_SMBCFG, cfg);
 281
 282         /* Divide by 8 to get a 6.25 MHz clock.  The later protocol
 283          * timings are based on this clock.
 284          */
 285         cfg |= PSC_SMBCFG_SET_DIV(PSC_SMBCFG_DIV8);
 286         WR(priv, PSC_SMBCFG, cfg);
 287         WR(priv, PSC_SMBMSK, PSC_SMBMSK_ALLMASK);
 288
 289         /* Set the protocol timer values.  See Table 71 in the
 290          * Au1550 Data Book for standard timing values.
 291          */
 292         WR(priv, PSC_SMBTMR, PSC_SMBTMR_SET_TH(0) | PSC_SMBTMR_SET_PS(15) | \
 293                 PSC_SMBTMR_SET_PU(15) | PSC_SMBTMR_SET_SH(15) | \
 294                 PSC_SMBTMR_SET_SU(15) | PSC_SMBTMR_SET_CL(15) | \
 295                 PSC_SMBTMR_SET_CH(15));
 296
 297         cfg |= PSC_SMBCFG_DE_ENABLE;
 298         WR(priv, PSC_SMBCFG, cfg);
 299         while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0)
 300                 cpu_relax();
 301
 302         WR(priv, PSC_CTRL, PSC_CTRL_SUSPEND);
 303 }
 304
 305 static void i2c_au1550_disable(struct i2c_au1550_data *priv)
 306 {
 307         WR(priv, PSC_SMBCFG, 0);
 308         WR(priv, PSC_CTRL, PSC_CTRL_DISABLE);
 309 }
 310
 311 /*
 312  * registering functions to load algorithms at runtime
 313  * Prior to calling us, the 50MHz clock frequency and routing
 314  * must have been set up for the PSC indicated by the adapter.
 315  */
 316 static int
 317 i2c_au1550_probe(struct platform_device *pdev)
 318 {
 319         struct i2c_au1550_data *priv;
 320         struct resource *r;
 321         int ret;
 322
 323         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 324         if (!r) {
 325                 ret = -ENODEV;
 326                 goto out;
 327         }
 328
 329         priv = kzalloc(sizeof(struct i2c_au1550_data), GFP_KERNEL);
 330         if (!priv) {
 331                 ret = -ENOMEM;
 332                 goto out;
 333         }
 334
 335         priv->ioarea = request_mem_region(r->start, resource_size(r),
 336                                           pdev->name);
 337         if (!priv->ioarea) {
 338                 ret = -EBUSY;
 339                 goto out_mem;
 340         }
 341
 342         priv->psc_base = ioremap(r->start, resource_size(r));
 343         if (!priv->psc_base) {
 344                 ret = -EIO;
 345                 goto out_map;
 346         }
 347         priv->xfer_timeout = 200;
 348
 349         priv->adap.nr = pdev->id;
 350         priv->adap.algo = &au1550_algo;
 351         priv->adap.algo_data = priv;
 352         priv->adap.dev.parent = &pdev->dev;
 353         strlcpy(priv->adap.name, "Au1xxx PSC I2C", sizeof(priv->adap.name));
 354
 355         /* Now, set up the PSC for SMBus PIO mode. */
 356         i2c_au1550_setup(priv);
 357
 358         ret = i2c_add_numbered_adapter(&priv->adap);
 359         if (ret == 0) {
 360                 platform_set_drvdata(pdev, priv);
 361                 return 0;
 362         }
 363
 364         i2c_au1550_disable(priv);
 365         iounmap(priv->psc_base);
 366 out_map:
 367         release_resource(priv->ioarea);
 368         kfree(priv->ioarea);
 369 out_mem:
 370         kfree(priv);
 371 out:
 372         return ret;
 373 }
 374
 375 static int i2c_au1550_remove(struct platform_device *pdev)
 376 {
 377         struct i2c_au1550_data *priv = platform_get_drvdata(pdev);
 378
 379         i2c_del_adapter(&priv->adap);
 380         i2c_au1550_disable(priv);
 381         iounmap(priv->psc_base);
 382         release_resource(priv->ioarea);
 383         kfree(priv->ioarea);
 384         kfree(priv);
 385         return 0;
 386 }
 387
 388 #ifdef CONFIG_PM
 389 static int i2c_au1550_suspend(struct device *dev)
 390 {
 391         struct i2c_au1550_data *priv = dev_get_drvdata(dev);
 392
 393         i2c_au1550_disable(priv);
 394
 395         return 0;
 396 }
 397
 398 static int i2c_au1550_resume(struct device *dev)
 399 {
 400         struct i2c_au1550_data *priv = dev_get_drvdata(dev);
 401
 402         i2c_au1550_setup(priv);
 403
 404         return 0;
 405 }
 406
 407 static const struct dev_pm_ops i2c_au1550_pmops = {
 408         .suspend        = i2c_au1550_suspend,
 409         .resume         = i2c_au1550_resume,
 410 };
 411
 412 #define AU1XPSC_SMBUS_PMOPS (&i2c_au1550_pmops)
 413
 414 #else
 415 #define AU1XPSC_SMBUS_PMOPS NULL
 416 #endif
 417
 418 static struct platform_driver au1xpsc_smbus_driver = {
 419         .driver = {
 420                 .name   = "au1xpsc_smbus",
 421                 .owner  = THIS_MODULE,
 422                 .pm     = AU1XPSC_SMBUS_PMOPS,
 423         },
 424         .probe          = i2c_au1550_probe,
 425         .remove         = i2c_au1550_remove,
 426 };
 427
 428 module_platform_driver(au1xpsc_smbus_driver);
 429
 430 MODULE_AUTHOR("Dan Malek, Embedded Edge, LLC.");
 431 MODULE_DESCRIPTION("SMBus adapter Alchemy pb1550");
 432 MODULE_LICENSE("GPL");
 433 MODULE_ALIAS("platform:au1xpsc_smbus");