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