drivers/i2c/busses/i2c-emev2.c

   1 /*
   2  * I2C driver for the Renesas EMEV2 SoC
   3  *
   4  * Copyright (C) 2015 Wolfram Sang <wsa@sang-engineering.com>
   5  * Copyright 2013 Codethink Ltd.
   6  * Copyright 2010-2015 Renesas Electronics Corporation
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2
  10  * as published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/clk.h>
  14 #include <linux/completion.h>
  15 #include <linux/device.h>
  16 #include <linux/i2c.h>
  17 #include <linux/init.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/io.h>
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/of_device.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/sched.h>
  25
  26 /* I2C Registers */
  27 #define I2C_OFS_IICACT0         0x00    /* start */
  28 #define I2C_OFS_IIC0            0x04    /* shift */
  29 #define I2C_OFS_IICC0           0x08    /* control */
  30 #define I2C_OFS_SVA0            0x0c    /* slave address */
  31 #define I2C_OFS_IICCL0          0x10    /* clock select */
  32 #define I2C_OFS_IICX0           0x14    /* extension */
  33 #define I2C_OFS_IICS0           0x18    /* status */
  34 #define I2C_OFS_IICSE0          0x1c    /* status For emulation */
  35 #define I2C_OFS_IICF0           0x20    /* IIC flag */
  36
  37 /* I2C IICACT0 Masks */
  38 #define I2C_BIT_IICE0           0x0001
  39
  40 /* I2C IICC0 Masks */
  41 #define I2C_BIT_LREL0           0x0040
  42 #define I2C_BIT_WREL0           0x0020
  43 #define I2C_BIT_SPIE0           0x0010
  44 #define I2C_BIT_WTIM0           0x0008
  45 #define I2C_BIT_ACKE0           0x0004
  46 #define I2C_BIT_STT0            0x0002
  47 #define I2C_BIT_SPT0            0x0001
  48
  49 /* I2C IICCL0 Masks */
  50 #define I2C_BIT_SMC0            0x0008
  51 #define I2C_BIT_DFC0            0x0004
  52
  53 /* I2C IICSE0 Masks */
  54 #define I2C_BIT_MSTS0           0x0080
  55 #define I2C_BIT_ALD0            0x0040
  56 #define I2C_BIT_EXC0            0x0020
  57 #define I2C_BIT_COI0            0x0010
  58 #define I2C_BIT_TRC0            0x0008
  59 #define I2C_BIT_ACKD0           0x0004
  60 #define I2C_BIT_STD0            0x0002
  61 #define I2C_BIT_SPD0            0x0001
  62
  63 /* I2C IICF0 Masks */
  64 #define I2C_BIT_STCF            0x0080
  65 #define I2C_BIT_IICBSY          0x0040
  66 #define I2C_BIT_STCEN           0x0002
  67 #define I2C_BIT_IICRSV          0x0001
  68
  69 struct em_i2c_device {
  70         void __iomem *base;
  71         struct i2c_adapter adap;
  72         struct completion msg_done;
  73         struct clk *sclk;
  74         struct i2c_client *slave;
  75 };
  76
  77 static inline void em_clear_set_bit(struct em_i2c_device *priv, u8 clear, u8 set, u8 reg)
  78 {
  79         writeb((readb(priv->base + reg) & ~clear) | set, priv->base + reg);
  80 }
  81
  82 static int em_i2c_wait_for_event(struct em_i2c_device *priv)
  83 {
  84         unsigned long time_left;
  85         int status;
  86
  87         reinit_completion(&priv->msg_done);
  88
  89         time_left = wait_for_completion_timeout(&priv->msg_done, priv->adap.timeout);
  90
  91         if (!time_left)
  92                 return -ETIMEDOUT;
  93
  94         status = readb(priv->base + I2C_OFS_IICSE0);
  95         return status & I2C_BIT_ALD0 ? -EAGAIN : status;
  96 }
  97
  98 static void em_i2c_stop(struct em_i2c_device *priv)
  99 {
 100         /* Send Stop condition */
 101         em_clear_set_bit(priv, 0, I2C_BIT_SPT0 | I2C_BIT_SPIE0, I2C_OFS_IICC0);
 102
 103         /* Wait for stop condition */
 104         em_i2c_wait_for_event(priv);
 105 }
 106
 107 static void em_i2c_reset(struct i2c_adapter *adap)
 108 {
 109         struct em_i2c_device *priv = i2c_get_adapdata(adap);
 110         int retr;
 111
 112         /* If I2C active */
 113         if (readb(priv->base + I2C_OFS_IICACT0) & I2C_BIT_IICE0) {
 114                 /* Disable I2C operation */
 115                 writeb(0, priv->base + I2C_OFS_IICACT0);
 116
 117                 retr = 1000;
 118                 while (readb(priv->base + I2C_OFS_IICACT0) == 1 && retr)
 119                         retr--;
 120                 WARN_ON(retr == 0);
 121         }
 122
 123         /* Transfer mode set */
 124         writeb(I2C_BIT_DFC0, priv->base + I2C_OFS_IICCL0);
 125
 126         /* Can Issue start without detecting a stop, Reservation disabled. */
 127         writeb(I2C_BIT_STCEN | I2C_BIT_IICRSV, priv->base + I2C_OFS_IICF0);
 128
 129         /* I2C enable, 9 bit interrupt mode */
 130         writeb(I2C_BIT_WTIM0, priv->base + I2C_OFS_IICC0);
 131
 132         /* Enable I2C operation */
 133         writeb(I2C_BIT_IICE0, priv->base + I2C_OFS_IICACT0);
 134
 135         retr = 1000;
 136         while (readb(priv->base + I2C_OFS_IICACT0) == 0 && retr)
 137                 retr--;
 138         WARN_ON(retr == 0);
 139 }
 140
 141 static int __em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msg,
 142                                 int stop)
 143 {
 144         struct em_i2c_device *priv = i2c_get_adapdata(adap);
 145         int count, status, read = !!(msg->flags & I2C_M_RD);
 146
 147         /* Send start condition */
 148         em_clear_set_bit(priv, 0, I2C_BIT_ACKE0 | I2C_BIT_WTIM0, I2C_OFS_IICC0);
 149         em_clear_set_bit(priv, 0, I2C_BIT_STT0, I2C_OFS_IICC0);
 150
 151         /* Send slave address and R/W type */
 152         writeb(i2c_8bit_addr_from_msg(msg), priv->base + I2C_OFS_IIC0);
 153
 154         /* Wait for transaction */
 155         status = em_i2c_wait_for_event(priv);
 156         if (status < 0)
 157                 goto out_reset;
 158
 159         /* Received NACK (result of setting slave address and R/W) */
 160         if (!(status & I2C_BIT_ACKD0)) {
 161                 em_i2c_stop(priv);
 162                 goto out;
 163         }
 164
 165         /* Extra setup for read transactions */
 166         if (read) {
 167                 /* 8 bit interrupt mode */
 168                 em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_ACKE0, I2C_OFS_IICC0);
 169                 em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_WREL0, I2C_OFS_IICC0);
 170
 171                 /* Wait for transaction */
 172                 status = em_i2c_wait_for_event(priv);
 173                 if (status < 0)
 174                         goto out_reset;
 175         }
 176
 177         /* Send / receive data */
 178         for (count = 0; count < msg->len; count++) {
 179                 if (read) { /* Read transaction */
 180                         msg->buf[count] = readb(priv->base + I2C_OFS_IIC0);
 181                         em_clear_set_bit(priv, 0, I2C_BIT_WREL0, I2C_OFS_IICC0);
 182
 183                 } else { /* Write transaction */
 184                         /* Received NACK */
 185                         if (!(status & I2C_BIT_ACKD0)) {
 186                                 em_i2c_stop(priv);
 187                                 goto out;
 188                         }
 189
 190                         /* Write data */
 191                         writeb(msg->buf[count], priv->base + I2C_OFS_IIC0);
 192                 }
 193
 194                 /* Wait for R/W transaction */
 195                 status = em_i2c_wait_for_event(priv);
 196                 if (status < 0)
 197                         goto out_reset;
 198         }
 199
 200         if (stop)
 201                 em_i2c_stop(priv);
 202
 203         return count;
 204
 205 out_reset:
 206         em_i2c_reset(adap);
 207 out:
 208         return status < 0 ? status : -ENXIO;
 209 }
 210
 211 static int em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 212         int num)
 213 {
 214         struct em_i2c_device *priv = i2c_get_adapdata(adap);
 215         int ret, i;
 216
 217         if (readb(priv->base + I2C_OFS_IICF0) & I2C_BIT_IICBSY)
 218                 return -EAGAIN;
 219
 220         for (i = 0; i < num; i++) {
 221                 ret = __em_i2c_xfer(adap, &msgs[i], (i == (num - 1)));
 222                 if (ret < 0)
 223                         return ret;
 224         }
 225
 226         /* I2C transfer completed */
 227         return num;
 228 }
 229
 230 static bool em_i2c_slave_irq(struct em_i2c_device *priv)
 231 {
 232         u8 status, value;
 233         enum i2c_slave_event event;
 234         int ret;
 235
 236         if (!priv->slave)
 237                 return false;
 238
 239         status = readb(priv->base + I2C_OFS_IICSE0);
 240
 241         /* Extension code, do not participate */
 242         if (status & I2C_BIT_EXC0) {
 243                 em_clear_set_bit(priv, 0, I2C_BIT_LREL0, I2C_OFS_IICC0);
 244                 return true;
 245         }
 246
 247         /* Stop detected, we don't know if it's for slave or master */
 248         if (status & I2C_BIT_SPD0) {
 249                 /* Notify slave device */
 250                 i2c_slave_event(priv->slave, I2C_SLAVE_STOP, &value);
 251                 /* Pretend we did not handle the interrupt */
 252                 return false;
 253         }
 254
 255         /* Only handle interrupts addressed to us */
 256         if (!(status & I2C_BIT_COI0))
 257                 return false;
 258
 259         /* Enable stop interrupts */
 260         em_clear_set_bit(priv, 0, I2C_BIT_SPIE0, I2C_OFS_IICC0);
 261
 262         /* Transmission or Reception */
 263         if (status & I2C_BIT_TRC0) {
 264                 if (status & I2C_BIT_ACKD0) {
 265                         /* 9 bit interrupt mode */
 266                         em_clear_set_bit(priv, 0, I2C_BIT_WTIM0, I2C_OFS_IICC0);
 267
 268                         /* Send data */
 269                         event = status & I2C_BIT_STD0 ?
 270                                 I2C_SLAVE_READ_REQUESTED :
 271                                 I2C_SLAVE_READ_PROCESSED;
 272                         i2c_slave_event(priv->slave, event, &value);
 273                         writeb(value, priv->base + I2C_OFS_IIC0);
 274                 } else {
 275                         /* NACK, stop transmitting */
 276                         em_clear_set_bit(priv, 0, I2C_BIT_LREL0, I2C_OFS_IICC0);
 277                 }
 278         } else {
 279                 /* 8 bit interrupt mode */
 280                 em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_ACKE0,
 281                                 I2C_OFS_IICC0);
 282                 em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_WREL0,
 283                                 I2C_OFS_IICC0);
 284
 285                 if (status & I2C_BIT_STD0) {
 286                         i2c_slave_event(priv->slave, I2C_SLAVE_WRITE_REQUESTED,
 287                                         &value);
 288                 } else {
 289                         /* Recv data */
 290                         value = readb(priv->base + I2C_OFS_IIC0);
 291                         ret = i2c_slave_event(priv->slave,
 292                                         I2C_SLAVE_WRITE_RECEIVED, &value);
 293                         if (ret < 0)
 294                                 em_clear_set_bit(priv, I2C_BIT_ACKE0, 0,
 295                                                 I2C_OFS_IICC0);
 296                 }
 297         }
 298
 299         return true;
 300 }
 301
 302 static irqreturn_t em_i2c_irq_handler(int this_irq, void *dev_id)
 303 {
 304         struct em_i2c_device *priv = dev_id;
 305
 306         if (em_i2c_slave_irq(priv))
 307                 return IRQ_HANDLED;
 308
 309         complete(&priv->msg_done);
 310
 311         return IRQ_HANDLED;
 312 }
 313
 314 static u32 em_i2c_func(struct i2c_adapter *adap)
 315 {
 316         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SLAVE;
 317 }
 318
 319 static int em_i2c_reg_slave(struct i2c_client *slave)
 320 {
 321         struct em_i2c_device *priv = i2c_get_adapdata(slave->adapter);
 322
 323         if (priv->slave)
 324                 return -EBUSY;
 325
 326         if (slave->flags & I2C_CLIENT_TEN)
 327                 return -EAFNOSUPPORT;
 328
 329         priv->slave = slave;
 330
 331         /* Set slave address */
 332         writeb(slave->addr << 1, priv->base + I2C_OFS_SVA0);
 333
 334         return 0;
 335 }
 336
 337 static int em_i2c_unreg_slave(struct i2c_client *slave)
 338 {
 339         struct em_i2c_device *priv = i2c_get_adapdata(slave->adapter);
 340
 341         WARN_ON(!priv->slave);
 342
 343         writeb(0, priv->base + I2C_OFS_SVA0);
 344
 345         priv->slave = NULL;
 346
 347         return 0;
 348 }
 349
 350 static const struct i2c_algorithm em_i2c_algo = {
 351         .master_xfer = em_i2c_xfer,
 352         .functionality = em_i2c_func,
 353         .reg_slave      = em_i2c_reg_slave,
 354         .unreg_slave    = em_i2c_unreg_slave,
 355 };
 356
 357 static int em_i2c_probe(struct platform_device *pdev)
 358 {
 359         struct em_i2c_device *priv;
 360         struct resource *r;
 361         int irq, ret;
 362
 363         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 364         if (!priv)
 365                 return -ENOMEM;
 366
 367         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 368         priv->base = devm_ioremap_resource(&pdev->dev, r);
 369         if (IS_ERR(priv->base))
 370                 return PTR_ERR(priv->base);
 371
 372         strlcpy(priv->adap.name, "EMEV2 I2C", sizeof(priv->adap.name));
 373
 374         priv->sclk = devm_clk_get(&pdev->dev, "sclk");
 375         if (IS_ERR(priv->sclk))
 376                 return PTR_ERR(priv->sclk);
 377
 378         ret = clk_prepare_enable(priv->sclk);
 379         if (ret)
 380                 return ret;
 381
 382         priv->adap.timeout = msecs_to_jiffies(100);
 383         priv->adap.retries = 5;
 384         priv->adap.dev.parent = &pdev->dev;
 385         priv->adap.algo = &em_i2c_algo;
 386         priv->adap.owner = THIS_MODULE;
 387         priv->adap.dev.of_node = pdev->dev.of_node;
 388
 389         init_completion(&priv->msg_done);
 390
 391         platform_set_drvdata(pdev, priv);
 392         i2c_set_adapdata(&priv->adap, priv);
 393
 394         em_i2c_reset(&priv->adap);
 395
 396         irq = platform_get_irq(pdev, 0);
 397         ret = devm_request_irq(&pdev->dev, irq, em_i2c_irq_handler, 0,
 398                                 "em_i2c", priv);
 399         if (ret)
 400                 goto err_clk;
 401
 402         ret = i2c_add_adapter(&priv->adap);
 403
 404         if (ret)
 405                 goto err_clk;
 406
 407         dev_info(&pdev->dev, "Added i2c controller %d, irq %d\n", priv->adap.nr, irq);
 408
 409         return 0;
 410
 411 err_clk:
 412         clk_disable_unprepare(priv->sclk);
 413         return ret;
 414 }
 415
 416 static int em_i2c_remove(struct platform_device *dev)
 417 {
 418         struct em_i2c_device *priv = platform_get_drvdata(dev);
 419
 420         i2c_del_adapter(&priv->adap);
 421         clk_disable_unprepare(priv->sclk);
 422
 423         return 0;
 424 }
 425
 426 static const struct of_device_id em_i2c_ids[] = {
 427         { .compatible = "renesas,iic-emev2", },
 428         { }
 429 };
 430
 431 static struct platform_driver em_i2c_driver = {
 432         .probe = em_i2c_probe,
 433         .remove = em_i2c_remove,
 434         .driver = {
 435                 .name = "em-i2c",
 436                 .of_match_table = em_i2c_ids,
 437         }
 438 };
 439 module_platform_driver(em_i2c_driver);
 440
 441 MODULE_DESCRIPTION("EMEV2 I2C bus driver");
 442 MODULE_AUTHOR("Ian Molton and Wolfram Sang <wsa@sang-engineering.com>");
 443 MODULE_LICENSE("GPL v2");
 444 MODULE_DEVICE_TABLE(of, em_i2c_ids);