drivers/i2c/busses/i2c-au1550.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * i2c-au1550.c: SMBus (i2c) adapter for Alchemy PSC interface
   4  * Copyright (C) 2004 Embedded Edge, LLC <dan@embeddededge.com>
   5  *
   6  * 2.6 port by Matt Porter <mporter@kernel.crashing.org>
   7  *
   8  * The documentation describes this as an SMBus controller, but it doesn't
   9  * understand any of the SMBus protocol in hardware.  It's really an I2C
  10  * controller that could emulate most of the SMBus in software.
  11  *
  12  * This is just a skeleton adapter to use with the Au1550 PSC
  13  * algorithm.  It was developed for the Pb1550, but will work with
  14  * any Au1550 board that has a similar PSC configuration.
  15  */
  16
  17 #include <linux/delay.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/errno.h>
  22 #include <linux/i2c.h>
  23 #include <linux/slab.h>
  24
  25 #include <asm/mach-au1x00/au1000.h>
  26 #include <asm/mach-au1x00/au1xxx_psc.h>
  27
  28 #define PSC_SEL         0x00
  29 #define PSC_CTRL        0x04
  30 #define PSC_SMBCFG      0x08
  31 #define PSC_SMBMSK      0x0C
  32 #define PSC_SMBPCR      0x10
  33 #define PSC_SMBSTAT     0x14
  34 #define PSC_SMBEVNT     0x18
  35 #define PSC_SMBTXRX     0x1C
  36 #define PSC_SMBTMR      0x20
  37
  38 struct i2c_au1550_data {
  39         void __iomem *psc_base;
  40         int     xfer_timeout;
  41         struct i2c_adapter adap;
  42 };
  43
  44 static inline void WR(struct i2c_au1550_data *a, int r, unsigned long v)
  45 {
  46         __raw_writel(v, a->psc_base + r);
  47         wmb();
  48 }
  49
  50 static inline unsigned long RD(struct i2c_au1550_data *a, int r)
  51 {
  52         return __raw_readl(a->psc_base + r);
  53 }
  54
  55 static int wait_xfer_done(struct i2c_au1550_data *adap)
  56 {
  57         int i;
  58
  59         /* Wait for Tx Buffer Empty */
  60         for (i = 0; i < adap->xfer_timeout; i++) {
  61                 if (RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_TE)
  62                         return 0;
  63
  64                 udelay(1);
  65         }
  66
  67         return -ETIMEDOUT;
  68 }
  69
  70 static int wait_ack(struct i2c_au1550_data *adap)
  71 {
  72         unsigned long stat;
  73
  74         if (wait_xfer_done(adap))
  75                 return -ETIMEDOUT;
  76
  77         stat = RD(adap, PSC_SMBEVNT);
  78         if ((stat & (PSC_SMBEVNT_DN | PSC_SMBEVNT_AN | PSC_SMBEVNT_AL)) != 0)
  79                 return -ETIMEDOUT;
  80
  81         return 0;
  82 }
  83
  84 static int wait_master_done(struct i2c_au1550_data *adap)
  85 {
  86         int i;
  87
  88         /* Wait for Master Done. */
  89         for (i = 0; i < 2 * adap->xfer_timeout; i++) {
  90                 if ((RD(adap, PSC_SMBEVNT) & PSC_SMBEVNT_MD) != 0)
  91                         return 0;
  92                 udelay(1);
  93         }
  94
  95         return -ETIMEDOUT;
  96 }
  97
  98 static int
  99 do_address(struct i2c_au1550_data *adap, unsigned int addr, int rd, int q)
 100 {
 101         unsigned long stat;
 102
 103         /* Reset the FIFOs, clear events. */
 104         stat = RD(adap, PSC_SMBSTAT);
 105         WR(adap, PSC_SMBEVNT, PSC_SMBEVNT_ALLCLR);
 106
 107         if (!(stat & PSC_SMBSTAT_TE) || !(stat & PSC_SMBSTAT_RE)) {
 108                 WR(adap, PSC_SMBPCR, PSC_SMBPCR_DC);
 109                 while ((RD(adap, PSC_SMBPCR) & PSC_SMBPCR_DC) != 0)
 110                         cpu_relax();
 111                 udelay(50);
 112         }
 113
 114         /* Write out the i2c chip address and specify operation */
 115         addr <<= 1;
 116         if (rd)
 117                 addr |= 1;
 118
 119         /* zero-byte xfers stop immediately */
 120         if (q)
 121                 addr |= PSC_SMBTXRX_STP;
 122
 123         /* Put byte into fifo, start up master. */
 124         WR(adap, PSC_SMBTXRX, addr);
 125         WR(adap, PSC_SMBPCR, PSC_SMBPCR_MS);
 126         if (wait_ack(adap))
 127                 return -EIO;
 128         return (q) ? wait_master_done(adap) : 0;
 129 }
 130
 131 static int wait_for_rx_byte(struct i2c_au1550_data *adap, unsigned char *out)
 132 {
 133         int j;
 134
 135         if (wait_xfer_done(adap))
 136                 return -EIO;
 137
 138         j =  adap->xfer_timeout * 100;
 139         do {
 140                 j--;
 141                 if (j <= 0)
 142                         return -EIO;
 143
 144                 if ((RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_RE) == 0)
 145                         j = 0;
 146                 else
 147                         udelay(1);
 148         } while (j > 0);
 149
 150         *out = RD(adap, PSC_SMBTXRX);
 151
 152         return 0;
 153 }
 154
 155 static int i2c_read(struct i2c_au1550_data *adap, unsigned char *buf,
 156                     unsigned int len)
 157 {
 158         int i;
 159
 160         if (len == 0)
 161                 return 0;
 162
 163         /* A read is performed by stuffing the transmit fifo with
 164          * zero bytes for timing, waiting for bytes to appear in the
 165          * receive fifo, then reading the bytes.
 166          */
 167         i = 0;
 168         while (i < (len - 1)) {
 169                 WR(adap, PSC_SMBTXRX, 0);
 170                 if (wait_for_rx_byte(adap, &buf[i]))
 171                         return -EIO;
 172
 173                 i++;
 174         }
 175
 176         /* The last byte has to indicate transfer done. */
 177         WR(adap, PSC_SMBTXRX, PSC_SMBTXRX_STP);
 178         if (wait_master_done(adap))
 179                 return -EIO;
 180
 181         buf[i] = (unsigned char)(RD(adap, PSC_SMBTXRX) & 0xff);
 182         return 0;
 183 }
 184
 185 static int i2c_write(struct i2c_au1550_data *adap, unsigned char *buf,
 186                      unsigned int len)
 187 {
 188         int i;
 189         unsigned long data;
 190
 191         if (len == 0)
 192                 return 0;
 193
 194         i = 0;
 195         while (i < (len-1)) {
 196                 data = buf[i];
 197                 WR(adap, PSC_SMBTXRX, data);
 198                 if (wait_ack(adap))
 199                         return -EIO;
 200                 i++;
 201         }
 202
 203         /* The last byte has to indicate transfer done. */
 204         data = buf[i];
 205         data |= PSC_SMBTXRX_STP;
 206         WR(adap, PSC_SMBTXRX, data);
 207         if (wait_master_done(adap))
 208                 return -EIO;
 209         return 0;
 210 }
 211
 212 static int
 213 au1550_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
 214 {
 215         struct i2c_au1550_data *adap = i2c_adap->algo_data;
 216         struct i2c_msg *p;
 217         int i, err = 0;
 218
 219         WR(adap, PSC_CTRL, PSC_CTRL_ENABLE);
 220
 221         for (i = 0; !err && i < num; i++) {
 222                 p = &msgs[i];
 223                 err = do_address(adap, p->addr, p->flags & I2C_M_RD,
 224                                  (p->len == 0));
 225                 if (err || !p->len)
 226                         continue;
 227                 if (p->flags & I2C_M_RD)
 228                         err = i2c_read(adap, p->buf, p->len);
 229                 else
 230                         err = i2c_write(adap, p->buf, p->len);
 231         }
 232
 233         /* Return the number of messages processed, or the error code.
 234         */
 235         if (err == 0)
 236                 err = num;
 237
 238         WR(adap, PSC_CTRL, PSC_CTRL_SUSPEND);
 239
 240         return err;
 241 }
 242
 243 static u32 au1550_func(struct i2c_adapter *adap)
 244 {
 245         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 246 }
 247
 248 static const struct i2c_algorithm au1550_algo = {
 249         .master_xfer    = au1550_xfer,
 250         .functionality  = au1550_func,
 251 };
 252
 253 static void i2c_au1550_setup(struct i2c_au1550_data *priv)
 254 {
 255         unsigned long cfg;
 256
 257         WR(priv, PSC_CTRL, PSC_CTRL_DISABLE);
 258         WR(priv, PSC_SEL, PSC_SEL_PS_SMBUSMODE);
 259         WR(priv, PSC_SMBCFG, 0);
 260         WR(priv, PSC_CTRL, PSC_CTRL_ENABLE);
 261         while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0)
 262                 cpu_relax();
 263
 264         cfg = PSC_SMBCFG_RT_FIFO8 | PSC_SMBCFG_TT_FIFO8 | PSC_SMBCFG_DD_DISABLE;
 265         WR(priv, PSC_SMBCFG, cfg);
 266
 267         /* Divide by 8 to get a 6.25 MHz clock.  The later protocol
 268          * timings are based on this clock.
 269          */
 270         cfg |= PSC_SMBCFG_SET_DIV(PSC_SMBCFG_DIV8);
 271         WR(priv, PSC_SMBCFG, cfg);
 272         WR(priv, PSC_SMBMSK, PSC_SMBMSK_ALLMASK);
 273
 274         /* Set the protocol timer values.  See Table 71 in the
 275          * Au1550 Data Book for standard timing values.
 276          */
 277         WR(priv, PSC_SMBTMR, PSC_SMBTMR_SET_TH(0) | PSC_SMBTMR_SET_PS(20) | \
 278                 PSC_SMBTMR_SET_PU(20) | PSC_SMBTMR_SET_SH(20) | \
 279                 PSC_SMBTMR_SET_SU(20) | PSC_SMBTMR_SET_CL(20) | \
 280                 PSC_SMBTMR_SET_CH(20));
 281
 282         cfg |= PSC_SMBCFG_DE_ENABLE;
 283         WR(priv, PSC_SMBCFG, cfg);
 284         while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0)
 285                 cpu_relax();
 286
 287         WR(priv, PSC_CTRL, PSC_CTRL_SUSPEND);
 288 }
 289
 290 static void i2c_au1550_disable(struct i2c_au1550_data *priv)
 291 {
 292         WR(priv, PSC_SMBCFG, 0);
 293         WR(priv, PSC_CTRL, PSC_CTRL_DISABLE);
 294 }
 295
 296 /*
 297  * registering functions to load algorithms at runtime
 298  * Prior to calling us, the 50MHz clock frequency and routing
 299  * must have been set up for the PSC indicated by the adapter.
 300  */
 301 static int
 302 i2c_au1550_probe(struct platform_device *pdev)
 303 {
 304         struct i2c_au1550_data *priv;
 305         struct resource *r;
 306         int ret;
 307
 308         priv = devm_kzalloc(&pdev->dev, sizeof(struct i2c_au1550_data),
 309                             GFP_KERNEL);
 310         if (!priv)
 311                 return -ENOMEM;
 312
 313         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 314         priv->psc_base = devm_ioremap_resource(&pdev->dev, r);
 315         if (IS_ERR(priv->psc_base))
 316                 return PTR_ERR(priv->psc_base);
 317
 318         priv->xfer_timeout = 200;
 319
 320         priv->adap.nr = pdev->id;
 321         priv->adap.algo = &au1550_algo;
 322         priv->adap.algo_data = priv;
 323         priv->adap.dev.parent = &pdev->dev;
 324         strlcpy(priv->adap.name, "Au1xxx PSC I2C", sizeof(priv->adap.name));
 325
 326         /* Now, set up the PSC for SMBus PIO mode. */
 327         i2c_au1550_setup(priv);
 328
 329         ret = i2c_add_numbered_adapter(&priv->adap);
 330         if (ret) {
 331                 i2c_au1550_disable(priv);
 332                 return ret;
 333         }
 334
 335         platform_set_drvdata(pdev, priv);
 336         return 0;
 337 }
 338
 339 static int i2c_au1550_remove(struct platform_device *pdev)
 340 {
 341         struct i2c_au1550_data *priv = platform_get_drvdata(pdev);
 342
 343         i2c_del_adapter(&priv->adap);
 344         i2c_au1550_disable(priv);
 345         return 0;
 346 }
 347
 348 #ifdef CONFIG_PM
 349 static int i2c_au1550_suspend(struct device *dev)
 350 {
 351         struct i2c_au1550_data *priv = dev_get_drvdata(dev);
 352
 353         i2c_au1550_disable(priv);
 354
 355         return 0;
 356 }
 357
 358 static int i2c_au1550_resume(struct device *dev)
 359 {
 360         struct i2c_au1550_data *priv = dev_get_drvdata(dev);
 361
 362         i2c_au1550_setup(priv);
 363
 364         return 0;
 365 }
 366
 367 static const struct dev_pm_ops i2c_au1550_pmops = {
 368         .suspend        = i2c_au1550_suspend,
 369         .resume         = i2c_au1550_resume,
 370 };
 371
 372 #define AU1XPSC_SMBUS_PMOPS (&i2c_au1550_pmops)
 373
 374 #else
 375 #define AU1XPSC_SMBUS_PMOPS NULL
 376 #endif
 377
 378 static struct platform_driver au1xpsc_smbus_driver = {
 379         .driver = {
 380                 .name   = "au1xpsc_smbus",
 381                 .pm     = AU1XPSC_SMBUS_PMOPS,
 382         },
 383         .probe          = i2c_au1550_probe,
 384         .remove         = i2c_au1550_remove,
 385 };
 386
 387 module_platform_driver(au1xpsc_smbus_driver);
 388
 389 MODULE_AUTHOR("Dan Malek, Embedded Edge, LLC.");
 390 MODULE_DESCRIPTION("SMBus adapter Alchemy pb1550");
 391 MODULE_LICENSE("GPL");
 392 MODULE_ALIAS("platform:au1xpsc_smbus");