drivers/i2c/busses/i2c-mlxcpld.c

   1 /*
   2  * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
   3  * Copyright (c) 2016 Michael Shych <michaels@mellanox.com>
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are met:
   7  *
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the names of the copyright holders nor the names of its
  14  *    contributors may be used to endorse or promote products derived from
  15  *    this software without specific prior written permission.
  16  *
  17  * Alternatively, this software may be distributed under the terms of the
  18  * GNU General Public License ("GPL") version 2 as published by the Free
  19  * Software Foundation.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  22  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  25  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  27  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  30  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31  * POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #include <linux/delay.h>
  35 #include <linux/i2c.h>
  36 #include <linux/init.h>
  37 #include <linux/io.h>
  38 #include <linux/kernel.h>
  39 #include <linux/module.h>
  40 #include <linux/platform_device.h>
  41
  42 /* General defines */
  43 #define MLXPLAT_CPLD_LPC_I2C_BASE_ADDR  0x2000
  44 #define MLXCPLD_I2C_DEVICE_NAME         "i2c_mlxcpld"
  45 #define MLXCPLD_I2C_VALID_FLAG          (I2C_M_RECV_LEN | I2C_M_RD)
  46 #define MLXCPLD_I2C_BUS_NUM             1
  47 #define MLXCPLD_I2C_DATA_REG_SZ         36
  48 #define MLXCPLD_I2C_MAX_ADDR_LEN        4
  49 #define MLXCPLD_I2C_RETR_NUM            2
  50 #define MLXCPLD_I2C_XFER_TO             500000 /* usec */
  51 #define MLXCPLD_I2C_POLL_TIME           2000   /* usec */
  52
  53 /* LPC I2C registers */
  54 #define MLXCPLD_LPCI2C_LPF_REG          0x0
  55 #define MLXCPLD_LPCI2C_CTRL_REG         0x1
  56 #define MLXCPLD_LPCI2C_HALF_CYC_REG     0x4
  57 #define MLXCPLD_LPCI2C_I2C_HOLD_REG     0x5
  58 #define MLXCPLD_LPCI2C_CMD_REG          0x6
  59 #define MLXCPLD_LPCI2C_NUM_DAT_REG      0x7
  60 #define MLXCPLD_LPCI2C_NUM_ADDR_REG     0x8
  61 #define MLXCPLD_LPCI2C_STATUS_REG       0x9
  62 #define MLXCPLD_LPCI2C_DATA_REG         0xa
  63
  64 /* LPC I2C masks and parametres */
  65 #define MLXCPLD_LPCI2C_RST_SEL_MASK     0x1
  66 #define MLXCPLD_LPCI2C_TRANS_END        0x1
  67 #define MLXCPLD_LPCI2C_STATUS_NACK      0x10
  68 #define MLXCPLD_LPCI2C_NO_IND           0
  69 #define MLXCPLD_LPCI2C_ACK_IND          1
  70 #define MLXCPLD_LPCI2C_NACK_IND         2
  71
  72 struct  mlxcpld_i2c_curr_xfer {
  73         u8 cmd;
  74         u8 addr_width;
  75         u8 data_len;
  76         u8 msg_num;
  77         struct i2c_msg *msg;
  78 };
  79
  80 struct mlxcpld_i2c_priv {
  81         struct i2c_adapter adap;
  82         u32 base_addr;
  83         struct mutex lock;
  84         struct  mlxcpld_i2c_curr_xfer xfer;
  85         struct device *dev;
  86 };
  87
  88 static void mlxcpld_i2c_lpc_write_buf(u8 *data, u8 len, u32 addr)
  89 {
  90         int i;
  91
  92         for (i = 0; i < len - len % 4; i += 4)
  93                 outl(*(u32 *)(data + i), addr + i);
  94         for (; i < len; ++i)
  95                 outb(*(data + i), addr + i);
  96 }
  97
  98 static void mlxcpld_i2c_lpc_read_buf(u8 *data, u8 len, u32 addr)
  99 {
 100         int i;
 101
 102         for (i = 0; i < len - len % 4; i += 4)
 103                 *(u32 *)(data + i) = inl(addr + i);
 104         for (; i < len; ++i)
 105                 *(data + i) = inb(addr + i);
 106 }
 107
 108 static void mlxcpld_i2c_read_comm(struct mlxcpld_i2c_priv *priv, u8 offs,
 109                                   u8 *data, u8 datalen)
 110 {
 111         u32 addr = priv->base_addr + offs;
 112
 113         switch (datalen) {
 114         case 1:
 115                 *(data) = inb(addr);
 116                 break;
 117         case 2:
 118                 *((u16 *)data) = inw(addr);
 119                 break;
 120         case 3:
 121                 *((u16 *)data) = inw(addr);
 122                 *(data + 2) = inb(addr + 2);
 123                 break;
 124         case 4:
 125                 *((u32 *)data) = inl(addr);
 126                 break;
 127         default:
 128                 mlxcpld_i2c_lpc_read_buf(data, datalen, addr);
 129                 break;
 130         }
 131 }
 132
 133 static void mlxcpld_i2c_write_comm(struct mlxcpld_i2c_priv *priv, u8 offs,
 134                                    u8 *data, u8 datalen)
 135 {
 136         u32 addr = priv->base_addr + offs;
 137
 138         switch (datalen) {
 139         case 1:
 140                 outb(*(data), addr);
 141                 break;
 142         case 2:
 143                 outw(*((u16 *)data), addr);
 144                 break;
 145         case 3:
 146                 outw(*((u16 *)data), addr);
 147                 outb(*(data + 2), addr + 2);
 148                 break;
 149         case 4:
 150                 outl(*((u32 *)data), addr);
 151                 break;
 152         default:
 153                 mlxcpld_i2c_lpc_write_buf(data, datalen, addr);
 154                 break;
 155         }
 156 }
 157
 158 /*
 159  * Check validity of received i2c messages parameters.
 160  * Returns 0 if OK, other - in case of invalid parameters.
 161  */
 162 static int mlxcpld_i2c_check_msg_params(struct mlxcpld_i2c_priv *priv,
 163                                         struct i2c_msg *msgs, int num)
 164 {
 165         int i;
 166
 167         if (!num) {
 168                 dev_err(priv->dev, "Incorrect 0 num of messages\n");
 169                 return -EINVAL;
 170         }
 171
 172         if (unlikely(msgs[0].addr > 0x7f)) {
 173                 dev_err(priv->dev, "Invalid address 0x%03x\n",
 174                         msgs[0].addr);
 175                 return -EINVAL;
 176         }
 177
 178         for (i = 0; i < num; ++i) {
 179                 if (unlikely(!msgs[i].buf)) {
 180                         dev_err(priv->dev, "Invalid buf in msg[%d]\n",
 181                                 i);
 182                         return -EINVAL;
 183                 }
 184                 if (unlikely(msgs[0].addr != msgs[i].addr)) {
 185                         dev_err(priv->dev, "Invalid addr in msg[%d]\n",
 186                                 i);
 187                         return -EINVAL;
 188                 }
 189         }
 190
 191         return 0;
 192 }
 193
 194 /*
 195  * Check if transfer is completed and status of operation.
 196  * Returns 0 - transfer completed (both ACK or NACK),
 197  * negative - transfer isn't finished.
 198  */
 199 static int mlxcpld_i2c_check_status(struct mlxcpld_i2c_priv *priv, int *status)
 200 {
 201         u8 val;
 202
 203         mlxcpld_i2c_read_comm(priv, MLXCPLD_LPCI2C_STATUS_REG, &val, 1);
 204
 205         if (val & MLXCPLD_LPCI2C_TRANS_END) {
 206                 if (val & MLXCPLD_LPCI2C_STATUS_NACK)
 207                         /*
 208                          * The slave is unable to accept the data. No such
 209                          * slave, command not understood, or unable to accept
 210                          * any more data.
 211                          */
 212                         *status = MLXCPLD_LPCI2C_NACK_IND;
 213                 else
 214                         *status = MLXCPLD_LPCI2C_ACK_IND;
 215                 return 0;
 216         }
 217         *status = MLXCPLD_LPCI2C_NO_IND;
 218
 219         return -EIO;
 220 }
 221
 222 static void mlxcpld_i2c_set_transf_data(struct mlxcpld_i2c_priv *priv,
 223                                         struct i2c_msg *msgs, int num,
 224                                         u8 comm_len)
 225 {
 226         priv->xfer.msg = msgs;
 227         priv->xfer.msg_num = num;
 228
 229         /*
 230          * All upper layers currently are never use transfer with more than
 231          * 2 messages. Actually, it's also not so relevant in Mellanox systems
 232          * because of HW limitation. Max size of transfer is not more than 32
 233          * bytes in the current x86 LPCI2C bridge.
 234          */
 235         priv->xfer.cmd = msgs[num - 1].flags & I2C_M_RD;
 236
 237         if (priv->xfer.cmd == I2C_M_RD && comm_len != msgs[0].len) {
 238                 priv->xfer.addr_width = msgs[0].len;
 239                 priv->xfer.data_len = comm_len - priv->xfer.addr_width;
 240         } else {
 241                 priv->xfer.addr_width = 0;
 242                 priv->xfer.data_len = comm_len;
 243         }
 244 }
 245
 246 /* Reset CPLD LPCI2C block */
 247 static void mlxcpld_i2c_reset(struct mlxcpld_i2c_priv *priv)
 248 {
 249         u8 val;
 250
 251         mutex_lock(&priv->lock);
 252
 253         mlxcpld_i2c_read_comm(priv, MLXCPLD_LPCI2C_CTRL_REG, &val, 1);
 254         val &= ~MLXCPLD_LPCI2C_RST_SEL_MASK;
 255         mlxcpld_i2c_write_comm(priv, MLXCPLD_LPCI2C_CTRL_REG, &val, 1);
 256
 257         mutex_unlock(&priv->lock);
 258 }
 259
 260 /* Make sure the CPLD is ready to start transmitting. */
 261 static int mlxcpld_i2c_check_busy(struct mlxcpld_i2c_priv *priv)
 262 {
 263         u8 val;
 264
 265         mlxcpld_i2c_read_comm(priv, MLXCPLD_LPCI2C_STATUS_REG, &val, 1);
 266
 267         if (val & MLXCPLD_LPCI2C_TRANS_END)
 268                 return 0;
 269
 270         return -EIO;
 271 }
 272
 273 static int mlxcpld_i2c_wait_for_free(struct mlxcpld_i2c_priv *priv)
 274 {
 275         int timeout = 0;
 276
 277         do {
 278                 if (!mlxcpld_i2c_check_busy(priv))
 279                         break;
 280                 usleep_range(MLXCPLD_I2C_POLL_TIME / 2, MLXCPLD_I2C_POLL_TIME);
 281                 timeout += MLXCPLD_I2C_POLL_TIME;
 282         } while (timeout <= MLXCPLD_I2C_XFER_TO);
 283
 284         if (timeout > MLXCPLD_I2C_XFER_TO)
 285                 return -ETIMEDOUT;
 286
 287         return 0;
 288 }
 289
 290 /*
 291  * Wait for master transfer to complete.
 292  * It puts current process to sleep until we get interrupt or timeout expires.
 293  * Returns the number of transferred or read bytes or error (<0).
 294  */
 295 static int mlxcpld_i2c_wait_for_tc(struct mlxcpld_i2c_priv *priv)
 296 {
 297         int status, i, timeout = 0;
 298         u8 datalen;
 299
 300         do {
 301                 usleep_range(MLXCPLD_I2C_POLL_TIME / 2, MLXCPLD_I2C_POLL_TIME);
 302                 if (!mlxcpld_i2c_check_status(priv, &status))
 303                         break;
 304                 timeout += MLXCPLD_I2C_POLL_TIME;
 305         } while (status == 0 && timeout < MLXCPLD_I2C_XFER_TO);
 306
 307         switch (status) {
 308         case MLXCPLD_LPCI2C_NO_IND:
 309                 return -ETIMEDOUT;
 310
 311         case MLXCPLD_LPCI2C_ACK_IND:
 312                 if (priv->xfer.cmd != I2C_M_RD)
 313                         return (priv->xfer.addr_width + priv->xfer.data_len);
 314
 315                 if (priv->xfer.msg_num == 1)
 316                         i = 0;
 317                 else
 318                         i = 1;
 319
 320                 if (!priv->xfer.msg[i].buf)
 321                         return -EINVAL;
 322
 323                 /*
 324                  * Actual read data len will be always the same as
 325                  * requested len. 0xff (line pull-up) will be returned
 326                  * if slave has no data to return. Thus don't read
 327                  * MLXCPLD_LPCI2C_NUM_DAT_REG reg from CPLD.
 328                  */
 329                 datalen = priv->xfer.data_len;
 330
 331                 mlxcpld_i2c_read_comm(priv, MLXCPLD_LPCI2C_DATA_REG,
 332                                       priv->xfer.msg[i].buf, datalen);
 333
 334                 return datalen;
 335
 336         case MLXCPLD_LPCI2C_NACK_IND:
 337                 return -ENXIO;
 338
 339         default:
 340                 return -EINVAL;
 341         }
 342 }
 343
 344 static void mlxcpld_i2c_xfer_msg(struct mlxcpld_i2c_priv *priv)
 345 {
 346         int i, len = 0;
 347         u8 cmd;
 348
 349         mlxcpld_i2c_write_comm(priv, MLXCPLD_LPCI2C_NUM_DAT_REG,
 350                                &priv->xfer.data_len, 1);
 351         mlxcpld_i2c_write_comm(priv, MLXCPLD_LPCI2C_NUM_ADDR_REG,
 352                                &priv->xfer.addr_width, 1);
 353
 354         for (i = 0; i < priv->xfer.msg_num; i++) {
 355                 if ((priv->xfer.msg[i].flags & I2C_M_RD) != I2C_M_RD) {
 356                         /* Don't write to CPLD buffer in read transaction */
 357                         mlxcpld_i2c_write_comm(priv, MLXCPLD_LPCI2C_DATA_REG +
 358                                                len, priv->xfer.msg[i].buf,
 359                                                priv->xfer.msg[i].len);
 360                         len += priv->xfer.msg[i].len;
 361                 }
 362         }
 363
 364         /*
 365          * Set target slave address with command for master transfer.
 366          * It should be latest executed function before CPLD transaction.
 367          */
 368         cmd = (priv->xfer.msg[0].addr << 1) | priv->xfer.cmd;
 369         mlxcpld_i2c_write_comm(priv, MLXCPLD_LPCI2C_CMD_REG, &cmd, 1);
 370 }
 371
 372 /*
 373  * Generic lpc-i2c transfer.
 374  * Returns the number of processed messages or error (<0).
 375  */
 376 static int mlxcpld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 377                             int num)
 378 {
 379         struct mlxcpld_i2c_priv *priv = i2c_get_adapdata(adap);
 380         u8 comm_len = 0;
 381         int i, err;
 382
 383         err = mlxcpld_i2c_check_msg_params(priv, msgs, num);
 384         if (err) {
 385                 dev_err(priv->dev, "Incorrect message\n");
 386                 return err;
 387         }
 388
 389         for (i = 0; i < num; ++i)
 390                 comm_len += msgs[i].len;
 391
 392         /* Check bus state */
 393         if (mlxcpld_i2c_wait_for_free(priv)) {
 394                 dev_err(priv->dev, "LPCI2C bridge is busy\n");
 395
 396                 /*
 397                  * Usually it means something serious has happened.
 398                  * We can not have unfinished previous transfer
 399                  * so it doesn't make any sense to try to stop it.
 400                  * Probably we were not able to recover from the
 401                  * previous error.
 402                  * The only reasonable thing - is soft reset.
 403                  */
 404                 mlxcpld_i2c_reset(priv);
 405                 if (mlxcpld_i2c_check_busy(priv)) {
 406                         dev_err(priv->dev, "LPCI2C bridge is busy after reset\n");
 407                         return -EIO;
 408                 }
 409         }
 410
 411         mlxcpld_i2c_set_transf_data(priv, msgs, num, comm_len);
 412
 413         mutex_lock(&priv->lock);
 414
 415         /* Do real transfer. Can't fail */
 416         mlxcpld_i2c_xfer_msg(priv);
 417
 418         /* Wait for transaction complete */
 419         err = mlxcpld_i2c_wait_for_tc(priv);
 420
 421         mutex_unlock(&priv->lock);
 422
 423         return err < 0 ? err : num;
 424 }
 425
 426 static u32 mlxcpld_i2c_func(struct i2c_adapter *adap)
 427 {
 428         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
 429 }
 430
 431 static const struct i2c_algorithm mlxcpld_i2c_algo = {
 432         .master_xfer    = mlxcpld_i2c_xfer,
 433         .functionality  = mlxcpld_i2c_func
 434 };
 435
 436 static struct i2c_adapter_quirks mlxcpld_i2c_quirks = {
 437         .flags = I2C_AQ_COMB_WRITE_THEN_READ,
 438         .max_read_len = MLXCPLD_I2C_DATA_REG_SZ - MLXCPLD_I2C_MAX_ADDR_LEN,
 439         .max_write_len = MLXCPLD_I2C_DATA_REG_SZ,
 440         .max_comb_1st_msg_len = 4,
 441 };
 442
 443 static struct i2c_adapter mlxcpld_i2c_adapter = {
 444         .owner          = THIS_MODULE,
 445         .name           = "i2c-mlxcpld",
 446         .class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
 447         .algo           = &mlxcpld_i2c_algo,
 448         .quirks         = &mlxcpld_i2c_quirks,
 449         .retries        = MLXCPLD_I2C_RETR_NUM,
 450         .nr             = MLXCPLD_I2C_BUS_NUM,
 451 };
 452
 453 static int mlxcpld_i2c_probe(struct platform_device *pdev)
 454 {
 455         struct mlxcpld_i2c_priv *priv;
 456         int err;
 457
 458         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 459         if (!priv)
 460                 return -ENOMEM;
 461
 462         mutex_init(&priv->lock);
 463         platform_set_drvdata(pdev, priv);
 464
 465         priv->dev = &pdev->dev;
 466
 467         /* Register with i2c layer */
 468         mlxcpld_i2c_adapter.timeout = usecs_to_jiffies(MLXCPLD_I2C_XFER_TO);
 469         priv->adap = mlxcpld_i2c_adapter;
 470         priv->adap.dev.parent = &pdev->dev;
 471         priv->base_addr = MLXPLAT_CPLD_LPC_I2C_BASE_ADDR;
 472         i2c_set_adapdata(&priv->adap, priv);
 473
 474         err = i2c_add_numbered_adapter(&priv->adap);
 475         if (err)
 476                 mutex_destroy(&priv->lock);
 477
 478         return err;
 479 }
 480
 481 static int mlxcpld_i2c_remove(struct platform_device *pdev)
 482 {
 483         struct mlxcpld_i2c_priv *priv = platform_get_drvdata(pdev);
 484
 485         i2c_del_adapter(&priv->adap);
 486         mutex_destroy(&priv->lock);
 487
 488         return 0;
 489 }
 490
 491 static struct platform_driver mlxcpld_i2c_driver = {
 492         .probe          = mlxcpld_i2c_probe,
 493         .remove         = mlxcpld_i2c_remove,
 494         .driver = {
 495                 .name = MLXCPLD_I2C_DEVICE_NAME,
 496         },
 497 };
 498
 499 module_platform_driver(mlxcpld_i2c_driver);
 500
 501 MODULE_AUTHOR("Michael Shych <michaels@mellanox.com>");
 502 MODULE_DESCRIPTION("Mellanox I2C-CPLD controller driver");
 503 MODULE_LICENSE("Dual BSD/GPL");
 504 MODULE_ALIAS("platform:i2c-mlxcpld");