drivers/i2c/busses/i2c-mxs.c

   1 /*
   2  * Freescale MXS I2C bus driver
   3  *
   4  * Copyright (C) 2011 Wolfram Sang, Pengutronix e.K.
   5  *
   6  * based on a (non-working) driver which was:
   7  *
   8  * Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
   9  *
  10  * TODO: add dma-support if platform-support for it is available
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  */
  18
  19 #include <linux/slab.h>
  20 #include <linux/device.h>
  21 #include <linux/module.h>
  22 #include <linux/i2c.h>
  23 #include <linux/err.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/completion.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/jiffies.h>
  28 #include <linux/io.h>
  29 #include <linux/pinctrl/consumer.h>
  30 #include <linux/of.h>
  31 #include <linux/of_device.h>
  32 #include <linux/of_i2c.h>
  33
  34 #include <mach/common.h>
  35
  36 #define DRIVER_NAME "mxs-i2c"
  37
  38 #define MXS_I2C_CTRL0           (0x00)
  39 #define MXS_I2C_CTRL0_SET       (0x04)
  40
  41 #define MXS_I2C_CTRL0_SFTRST                    0x80000000
  42 #define MXS_I2C_CTRL0_SEND_NAK_ON_LAST          0x02000000
  43 #define MXS_I2C_CTRL0_RETAIN_CLOCK              0x00200000
  44 #define MXS_I2C_CTRL0_POST_SEND_STOP            0x00100000
  45 #define MXS_I2C_CTRL0_PRE_SEND_START            0x00080000
  46 #define MXS_I2C_CTRL0_MASTER_MODE               0x00020000
  47 #define MXS_I2C_CTRL0_DIRECTION                 0x00010000
  48 #define MXS_I2C_CTRL0_XFER_COUNT(v)             ((v) & 0x0000FFFF)
  49
  50 #define MXS_I2C_CTRL1           (0x40)
  51 #define MXS_I2C_CTRL1_SET       (0x44)
  52 #define MXS_I2C_CTRL1_CLR       (0x48)
  53
  54 #define MXS_I2C_CTRL1_BUS_FREE_IRQ              0x80
  55 #define MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ     0x40
  56 #define MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ          0x20
  57 #define MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ    0x10
  58 #define MXS_I2C_CTRL1_EARLY_TERM_IRQ            0x08
  59 #define MXS_I2C_CTRL1_MASTER_LOSS_IRQ           0x04
  60 #define MXS_I2C_CTRL1_SLAVE_STOP_IRQ            0x02
  61 #define MXS_I2C_CTRL1_SLAVE_IRQ                 0x01
  62
  63 #define MXS_I2C_IRQ_MASK        (MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ | \
  64                                  MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ | \
  65                                  MXS_I2C_CTRL1_EARLY_TERM_IRQ | \
  66                                  MXS_I2C_CTRL1_MASTER_LOSS_IRQ | \
  67                                  MXS_I2C_CTRL1_SLAVE_STOP_IRQ | \
  68                                  MXS_I2C_CTRL1_SLAVE_IRQ)
  69
  70 #define MXS_I2C_QUEUECTRL       (0x60)
  71 #define MXS_I2C_QUEUECTRL_SET   (0x64)
  72 #define MXS_I2C_QUEUECTRL_CLR   (0x68)
  73
  74 #define MXS_I2C_QUEUECTRL_QUEUE_RUN             0x20
  75 #define MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE        0x04
  76
  77 #define MXS_I2C_QUEUESTAT       (0x70)
  78 #define MXS_I2C_QUEUESTAT_RD_QUEUE_EMPTY        0x00002000
  79 #define MXS_I2C_QUEUESTAT_WRITE_QUEUE_CNT_MASK  0x0000001F
  80
  81 #define MXS_I2C_QUEUECMD        (0x80)
  82
  83 #define MXS_I2C_QUEUEDATA       (0x90)
  84
  85 #define MXS_I2C_DATA            (0xa0)
  86
  87
  88 #define MXS_CMD_I2C_SELECT      (MXS_I2C_CTRL0_RETAIN_CLOCK |   \
  89                                  MXS_I2C_CTRL0_PRE_SEND_START | \
  90                                  MXS_I2C_CTRL0_MASTER_MODE |    \
  91                                  MXS_I2C_CTRL0_DIRECTION |      \
  92                                  MXS_I2C_CTRL0_XFER_COUNT(1))
  93
  94 #define MXS_CMD_I2C_WRITE       (MXS_I2C_CTRL0_PRE_SEND_START | \
  95                                  MXS_I2C_CTRL0_MASTER_MODE |    \
  96                                  MXS_I2C_CTRL0_DIRECTION)
  97
  98 #define MXS_CMD_I2C_READ        (MXS_I2C_CTRL0_SEND_NAK_ON_LAST | \
  99                                  MXS_I2C_CTRL0_MASTER_MODE)
 100
 101 /**
 102  * struct mxs_i2c_dev - per device, private MXS-I2C data
 103  *
 104  * @dev: driver model device node
 105  * @regs: IO registers pointer
 106  * @cmd_complete: completion object for transaction wait
 107  * @cmd_err: error code for last transaction
 108  * @adapter: i2c subsystem adapter node
 109  */
 110 struct mxs_i2c_dev {
 111         struct device *dev;
 112         void __iomem *regs;
 113         struct completion cmd_complete;
 114         u32 cmd_err;
 115         struct i2c_adapter adapter;
 116 };
 117
 118 /*
 119  * TODO: check if calls to here are really needed. If not, we could get rid of
 120  * mxs_reset_block and the mach-dependency. Needs an I2C analyzer, probably.
 121  */
 122 static void mxs_i2c_reset(struct mxs_i2c_dev *i2c)
 123 {
 124         mxs_reset_block(i2c->regs);
 125         writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
 126         writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE,
 127                         i2c->regs + MXS_I2C_QUEUECTRL_SET);
 128 }
 129
 130 static void mxs_i2c_pioq_setup_read(struct mxs_i2c_dev *i2c, u8 addr, int len,
 131                                         int flags)
 132 {
 133         u32 data;
 134
 135         writel(MXS_CMD_I2C_SELECT, i2c->regs + MXS_I2C_QUEUECMD);
 136
 137         data = (addr << 1) | I2C_SMBUS_READ;
 138         writel(data, i2c->regs + MXS_I2C_DATA);
 139
 140         data = MXS_CMD_I2C_READ | MXS_I2C_CTRL0_XFER_COUNT(len) | flags;
 141         writel(data, i2c->regs + MXS_I2C_QUEUECMD);
 142 }
 143
 144 static void mxs_i2c_pioq_setup_write(struct mxs_i2c_dev *i2c,
 145                                     u8 addr, u8 *buf, int len, int flags)
 146 {
 147         u32 data;
 148         int i, shifts_left;
 149
 150         data = MXS_CMD_I2C_WRITE | MXS_I2C_CTRL0_XFER_COUNT(len + 1) | flags;
 151         writel(data, i2c->regs + MXS_I2C_QUEUECMD);
 152
 153         /*
 154          * We have to copy the slave address (u8) and buffer (arbitrary number
 155          * of u8) into the data register (u32). To achieve that, the u8 are put
 156          * into the MSBs of 'data' which is then shifted for the next u8. When
 157          * appropriate, 'data' is written to MXS_I2C_DATA. So, the first u32
 158          * looks like this:
 159          *
 160          *  3          2          1          0
 161          * 10987654|32109876|54321098|76543210
 162          * --------+--------+--------+--------
 163          * buffer+2|buffer+1|buffer+0|slave_addr
 164          */
 165
 166         data = ((addr << 1) | I2C_SMBUS_WRITE) << 24;
 167
 168         for (i = 0; i < len; i++) {
 169                 data >>= 8;
 170                 data |= buf[i] << 24;
 171                 if ((i & 3) == 2)
 172                         writel(data, i2c->regs + MXS_I2C_DATA);
 173         }
 174
 175         /* Write out the remaining bytes if any */
 176         shifts_left = 24 - (i & 3) * 8;
 177         if (shifts_left)
 178                 writel(data >> shifts_left, i2c->regs + MXS_I2C_DATA);
 179 }
 180
 181 /*
 182  * TODO: should be replaceable with a waitqueue and RD_QUEUE_IRQ (setting the
 183  * rd_threshold to 1). Couldn't get this to work, though.
 184  */
 185 static int mxs_i2c_wait_for_data(struct mxs_i2c_dev *i2c)
 186 {
 187         unsigned long timeout = jiffies + msecs_to_jiffies(1000);
 188
 189         while (readl(i2c->regs + MXS_I2C_QUEUESTAT)
 190                         & MXS_I2C_QUEUESTAT_RD_QUEUE_EMPTY) {
 191                         if (time_after(jiffies, timeout))
 192                                 return -ETIMEDOUT;
 193                         cond_resched();
 194         }
 195
 196         return 0;
 197 }
 198
 199 static int mxs_i2c_finish_read(struct mxs_i2c_dev *i2c, u8 *buf, int len)
 200 {
 201         u32 data;
 202         int i;
 203
 204         for (i = 0; i < len; i++) {
 205                 if ((i & 3) == 0) {
 206                         if (mxs_i2c_wait_for_data(i2c))
 207                                 return -ETIMEDOUT;
 208                         data = readl(i2c->regs + MXS_I2C_QUEUEDATA);
 209                 }
 210                 buf[i] = data & 0xff;
 211                 data >>= 8;
 212         }
 213
 214         return 0;
 215 }
 216
 217 /*
 218  * Low level master read/write transaction.
 219  */
 220 static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
 221                                 int stop)
 222 {
 223         struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
 224         int ret;
 225         int flags;
 226
 227         dev_dbg(i2c->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
 228                 msg->addr, msg->len, msg->flags, stop);
 229
 230         if (msg->len == 0)
 231                 return -EINVAL;
 232
 233         init_completion(&i2c->cmd_complete);
 234         i2c->cmd_err = 0;
 235
 236         flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
 237
 238         if (msg->flags & I2C_M_RD)
 239                 mxs_i2c_pioq_setup_read(i2c, msg->addr, msg->len, flags);
 240         else
 241                 mxs_i2c_pioq_setup_write(i2c, msg->addr, msg->buf, msg->len,
 242                                         flags);
 243
 244         writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
 245                         i2c->regs + MXS_I2C_QUEUECTRL_SET);
 246
 247         ret = wait_for_completion_timeout(&i2c->cmd_complete,
 248                                                 msecs_to_jiffies(1000));
 249         if (ret == 0)
 250                 goto timeout;
 251
 252         if ((!i2c->cmd_err) && (msg->flags & I2C_M_RD)) {
 253                 ret = mxs_i2c_finish_read(i2c, msg->buf, msg->len);
 254                 if (ret)
 255                         goto timeout;
 256         }
 257
 258         if (i2c->cmd_err == -ENXIO)
 259                 mxs_i2c_reset(i2c);
 260         else
 261                 writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
 262                                 i2c->regs + MXS_I2C_QUEUECTRL_CLR);
 263
 264         dev_dbg(i2c->dev, "Done with err=%d\n", i2c->cmd_err);
 265
 266         return i2c->cmd_err;
 267
 268 timeout:
 269         dev_dbg(i2c->dev, "Timeout!\n");
 270         mxs_i2c_reset(i2c);
 271         return -ETIMEDOUT;
 272 }
 273
 274 static int mxs_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 275                         int num)
 276 {
 277         int i;
 278         int err;
 279
 280         for (i = 0; i < num; i++) {
 281                 err = mxs_i2c_xfer_msg(adap, &msgs[i], i == (num - 1));
 282                 if (err)
 283                         return err;
 284         }
 285
 286         return num;
 287 }
 288
 289 static u32 mxs_i2c_func(struct i2c_adapter *adap)
 290 {
 291         return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
 292 }
 293
 294 static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id)
 295 {
 296         struct mxs_i2c_dev *i2c = dev_id;
 297         u32 stat = readl(i2c->regs + MXS_I2C_CTRL1) & MXS_I2C_IRQ_MASK;
 298         bool is_last_cmd;
 299
 300         if (!stat)
 301                 return IRQ_NONE;
 302
 303         if (stat & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
 304                 i2c->cmd_err = -ENXIO;
 305         else if (stat & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
 306                     MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
 307                     MXS_I2C_CTRL1_SLAVE_STOP_IRQ | MXS_I2C_CTRL1_SLAVE_IRQ))
 308                 /* MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ is only for slaves */
 309                 i2c->cmd_err = -EIO;
 310
 311         is_last_cmd = (readl(i2c->regs + MXS_I2C_QUEUESTAT) &
 312                 MXS_I2C_QUEUESTAT_WRITE_QUEUE_CNT_MASK) == 0;
 313
 314         if (is_last_cmd || i2c->cmd_err)
 315                 complete(&i2c->cmd_complete);
 316
 317         writel(stat, i2c->regs + MXS_I2C_CTRL1_CLR);
 318
 319         return IRQ_HANDLED;
 320 }
 321
 322 static const struct i2c_algorithm mxs_i2c_algo = {
 323         .master_xfer = mxs_i2c_xfer,
 324         .functionality = mxs_i2c_func,
 325 };
 326
 327 static int __devinit mxs_i2c_probe(struct platform_device *pdev)
 328 {
 329         struct device *dev = &pdev->dev;
 330         struct mxs_i2c_dev *i2c;
 331         struct i2c_adapter *adap;
 332         struct pinctrl *pinctrl;
 333         struct resource *res;
 334         resource_size_t res_size;
 335         int err, irq;
 336
 337         pinctrl = devm_pinctrl_get_select_default(dev);
 338         if (IS_ERR(pinctrl))
 339                 return PTR_ERR(pinctrl);
 340
 341         i2c = devm_kzalloc(dev, sizeof(struct mxs_i2c_dev), GFP_KERNEL);
 342         if (!i2c)
 343                 return -ENOMEM;
 344
 345         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 346         if (!res)
 347                 return -ENOENT;
 348
 349         res_size = resource_size(res);
 350         if (!devm_request_mem_region(dev, res->start, res_size, res->name))
 351                 return -EBUSY;
 352
 353         i2c->regs = devm_ioremap_nocache(dev, res->start, res_size);
 354         if (!i2c->regs)
 355                 return -EBUSY;
 356
 357         irq = platform_get_irq(pdev, 0);
 358         if (irq < 0)
 359                 return irq;
 360
 361         err = devm_request_irq(dev, irq, mxs_i2c_isr, 0, dev_name(dev), i2c);
 362         if (err)
 363                 return err;
 364
 365         i2c->dev = dev;
 366         platform_set_drvdata(pdev, i2c);
 367
 368         /* Do reset to enforce correct startup after pinmuxing */
 369         mxs_i2c_reset(i2c);
 370
 371         adap = &i2c->adapter;
 372         strlcpy(adap->name, "MXS I2C adapter", sizeof(adap->name));
 373         adap->owner = THIS_MODULE;
 374         adap->algo = &mxs_i2c_algo;
 375         adap->dev.parent = dev;
 376         adap->nr = pdev->id;
 377         adap->dev.of_node = pdev->dev.of_node;
 378         i2c_set_adapdata(adap, i2c);
 379         err = i2c_add_numbered_adapter(adap);
 380         if (err) {
 381                 dev_err(dev, "Failed to add adapter (%d)\n", err);
 382                 writel(MXS_I2C_CTRL0_SFTRST,
 383                                 i2c->regs + MXS_I2C_CTRL0_SET);
 384                 return err;
 385         }
 386
 387         of_i2c_register_devices(adap);
 388
 389         return 0;
 390 }
 391
 392 static int __devexit mxs_i2c_remove(struct platform_device *pdev)
 393 {
 394         struct mxs_i2c_dev *i2c = platform_get_drvdata(pdev);
 395         int ret;
 396
 397         ret = i2c_del_adapter(&i2c->adapter);
 398         if (ret)
 399                 return -EBUSY;
 400
 401         writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);
 402
 403         platform_set_drvdata(pdev, NULL);
 404
 405         return 0;
 406 }
 407
 408 static const struct of_device_id mxs_i2c_dt_ids[] = {
 409         { .compatible = "fsl,imx28-i2c", },
 410         { /* sentinel */ }
 411 };
 412 MODULE_DEVICE_TABLE(of, mxs_i2c_dt_ids);
 413
 414 static struct platform_driver mxs_i2c_driver = {
 415         .driver = {
 416                    .name = DRIVER_NAME,
 417                    .owner = THIS_MODULE,
 418                    .of_match_table = mxs_i2c_dt_ids,
 419                    },
 420         .remove = __devexit_p(mxs_i2c_remove),
 421 };
 422
 423 static int __init mxs_i2c_init(void)
 424 {
 425         return platform_driver_probe(&mxs_i2c_driver, mxs_i2c_probe);
 426 }
 427 subsys_initcall(mxs_i2c_init);
 428
 429 static void __exit mxs_i2c_exit(void)
 430 {
 431         platform_driver_unregister(&mxs_i2c_driver);
 432 }
 433 module_exit(mxs_i2c_exit);
 434
 435 MODULE_AUTHOR("Wolfram Sang <w.sang@pengutronix.de>");
 436 MODULE_DESCRIPTION("MXS I2C Bus Driver");
 437 MODULE_LICENSE("GPL");
 438 MODULE_ALIAS("platform:" DRIVER_NAME);