drivers/i2c/busses/i2c-sirf.c

   1 /*
   2  * I2C bus driver for CSR SiRFprimaII
   3  *
   4  * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
   5  *
   6  * Licensed under GPLv2 or later.
   7  */
   8
   9 #include <linux/interrupt.h>
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/i2c.h>
  15 #include <linux/clk.h>
  16 #include <linux/err.h>
  17 #include <linux/io.h>
  18
  19 #define SIRFSOC_I2C_CLK_CTRL            0x00
  20 #define SIRFSOC_I2C_STATUS              0x0C
  21 #define SIRFSOC_I2C_CTRL                0x10
  22 #define SIRFSOC_I2C_IO_CTRL             0x14
  23 #define SIRFSOC_I2C_SDA_DELAY           0x18
  24 #define SIRFSOC_I2C_CMD_START           0x1C
  25 #define SIRFSOC_I2C_CMD_BUF             0x30
  26 #define SIRFSOC_I2C_DATA_BUF            0x80
  27
  28 #define SIRFSOC_I2C_CMD_BUF_MAX         16
  29 #define SIRFSOC_I2C_DATA_BUF_MAX        16
  30
  31 #define SIRFSOC_I2C_CMD(x)              (SIRFSOC_I2C_CMD_BUF + (x)*0x04)
  32 #define SIRFSOC_I2C_DATA_MASK(x)        (0xFF<<(((x)&3)*8))
  33 #define SIRFSOC_I2C_DATA_SHIFT(x)       (((x)&3)*8)
  34
  35 #define SIRFSOC_I2C_DIV_MASK            (0xFFFF)
  36
  37 /* I2C status flags */
  38 #define SIRFSOC_I2C_STAT_BUSY           BIT(0)
  39 #define SIRFSOC_I2C_STAT_TIP            BIT(1)
  40 #define SIRFSOC_I2C_STAT_NACK           BIT(2)
  41 #define SIRFSOC_I2C_STAT_TR_INT         BIT(4)
  42 #define SIRFSOC_I2C_STAT_STOP           BIT(6)
  43 #define SIRFSOC_I2C_STAT_CMD_DONE       BIT(8)
  44 #define SIRFSOC_I2C_STAT_ERR            BIT(9)
  45 #define SIRFSOC_I2C_CMD_INDEX           (0x1F<<16)
  46
  47 /* I2C control flags */
  48 #define SIRFSOC_I2C_RESET               BIT(0)
  49 #define SIRFSOC_I2C_CORE_EN             BIT(1)
  50 #define SIRFSOC_I2C_MASTER_MODE         BIT(2)
  51 #define SIRFSOC_I2C_CMD_DONE_EN         BIT(11)
  52 #define SIRFSOC_I2C_ERR_INT_EN          BIT(12)
  53
  54 #define SIRFSOC_I2C_SDA_DELAY_MASK      (0xFF)
  55 #define SIRFSOC_I2C_SCLF_FILTER         (3<<8)
  56
  57 #define SIRFSOC_I2C_START_CMD           BIT(0)
  58
  59 #define SIRFSOC_I2C_CMD_RP(x)           ((x)&0x7)
  60 #define SIRFSOC_I2C_NACK                BIT(3)
  61 #define SIRFSOC_I2C_WRITE               BIT(4)
  62 #define SIRFSOC_I2C_READ                BIT(5)
  63 #define SIRFSOC_I2C_STOP                BIT(6)
  64 #define SIRFSOC_I2C_START               BIT(7)
  65
  66 #define SIRFSOC_I2C_DEFAULT_SPEED 100000
  67 #define SIRFSOC_I2C_ERR_NOACK      1
  68 #define SIRFSOC_I2C_ERR_TIMEOUT    2
  69
  70 struct sirfsoc_i2c {
  71         void __iomem *base;
  72         struct clk *clk;
  73         u32 cmd_ptr;            /* Current position in CMD buffer */
  74         u8 *buf;                /* Buffer passed by user */
  75         u32 msg_len;            /* Message length */
  76         u32 finished_len;       /* number of bytes read/written */
  77         u32 read_cmd_len;       /* number of read cmd sent */
  78         int msg_read;           /* 1 indicates a read message */
  79         int err_status;         /* 1 indicates an error on bus */
  80
  81         u32 sda_delay;          /* For suspend/resume */
  82         u32 clk_div;
  83         int last;               /* Last message in transfer, STOP cmd can be sent */
  84
  85         struct completion done; /* indicates completion of message transfer */
  86         struct i2c_adapter adapter;
  87 };
  88
  89 static void i2c_sirfsoc_read_data(struct sirfsoc_i2c *siic)
  90 {
  91         u32 data = 0;
  92         int i;
  93
  94         for (i = 0; i < siic->read_cmd_len; i++) {
  95                 if (!(i & 0x3))
  96                         data = readl(siic->base + SIRFSOC_I2C_DATA_BUF + i);
  97                 siic->buf[siic->finished_len++] =
  98                         (u8)((data & SIRFSOC_I2C_DATA_MASK(i)) >>
  99                                 SIRFSOC_I2C_DATA_SHIFT(i));
 100         }
 101 }
 102
 103 static void i2c_sirfsoc_queue_cmd(struct sirfsoc_i2c *siic)
 104 {
 105         u32 regval;
 106         int i = 0;
 107
 108         if (siic->msg_read) {
 109                 while (((siic->finished_len + i) < siic->msg_len)
 110                                 && (siic->cmd_ptr < SIRFSOC_I2C_CMD_BUF_MAX)) {
 111                         regval = SIRFSOC_I2C_READ | SIRFSOC_I2C_CMD_RP(0);
 112                         if (((siic->finished_len + i) ==
 113                                         (siic->msg_len - 1)) && siic->last)
 114                                 regval |= SIRFSOC_I2C_STOP | SIRFSOC_I2C_NACK;
 115                         writel(regval,
 116                                 siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
 117                         i++;
 118                 }
 119
 120                 siic->read_cmd_len = i;
 121         } else {
 122                 while ((siic->cmd_ptr < SIRFSOC_I2C_CMD_BUF_MAX - 1)
 123                                 && (siic->finished_len < siic->msg_len)) {
 124                         regval = SIRFSOC_I2C_WRITE | SIRFSOC_I2C_CMD_RP(0);
 125                         if ((siic->finished_len == (siic->msg_len - 1))
 126                                 && siic->last)
 127                                 regval |= SIRFSOC_I2C_STOP;
 128                         writel(regval,
 129                                 siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
 130                         writel(siic->buf[siic->finished_len++],
 131                                 siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
 132                 }
 133         }
 134         siic->cmd_ptr = 0;
 135
 136         /* Trigger the transfer */
 137         writel(SIRFSOC_I2C_START_CMD, siic->base + SIRFSOC_I2C_CMD_START);
 138 }
 139
 140 static irqreturn_t i2c_sirfsoc_irq(int irq, void *dev_id)
 141 {
 142         struct sirfsoc_i2c *siic = (struct sirfsoc_i2c *)dev_id;
 143         u32 i2c_stat = readl(siic->base + SIRFSOC_I2C_STATUS);
 144
 145         if (i2c_stat & SIRFSOC_I2C_STAT_ERR) {
 146                 /* Error conditions */
 147                 siic->err_status = SIRFSOC_I2C_ERR_NOACK;
 148                 writel(SIRFSOC_I2C_STAT_ERR, siic->base + SIRFSOC_I2C_STATUS);
 149
 150                 if (i2c_stat & SIRFSOC_I2C_STAT_NACK)
 151                         dev_dbg(&siic->adapter.dev, "ACK not received\n");
 152                 else
 153                         dev_err(&siic->adapter.dev, "I2C error\n");
 154
 155                 /*
 156                  * Due to hardware ANOMALY, we need to reset I2C earlier after
 157                  * we get NOACK while accessing non-existing clients, otherwise
 158                  * we will get errors even we access existing clients later
 159                  */
 160                 writel(readl(siic->base + SIRFSOC_I2C_CTRL) | SIRFSOC_I2C_RESET,
 161                                 siic->base + SIRFSOC_I2C_CTRL);
 162                 while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
 163                         cpu_relax();
 164
 165                 complete(&siic->done);
 166         } else if (i2c_stat & SIRFSOC_I2C_STAT_CMD_DONE) {
 167                 /* CMD buffer execution complete */
 168                 if (siic->msg_read)
 169                         i2c_sirfsoc_read_data(siic);
 170                 if (siic->finished_len == siic->msg_len)
 171                         complete(&siic->done);
 172                 else /* Fill a new CMD buffer for left data */
 173                         i2c_sirfsoc_queue_cmd(siic);
 174
 175                 writel(SIRFSOC_I2C_STAT_CMD_DONE, siic->base + SIRFSOC_I2C_STATUS);
 176         }
 177
 178         return IRQ_HANDLED;
 179 }
 180
 181 static void i2c_sirfsoc_set_address(struct sirfsoc_i2c *siic,
 182         struct i2c_msg *msg)
 183 {
 184         unsigned char addr;
 185         u32 regval = SIRFSOC_I2C_START | SIRFSOC_I2C_CMD_RP(0) | SIRFSOC_I2C_WRITE;
 186
 187         /* no data and last message -> add STOP */
 188         if (siic->last && (msg->len == 0))
 189                 regval |= SIRFSOC_I2C_STOP;
 190
 191         writel(regval, siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
 192
 193         addr = i2c_8bit_addr_from_msg(msg);
 194
 195         /* Reverse direction bit */
 196         if (msg->flags & I2C_M_REV_DIR_ADDR)
 197                 addr ^= 1;
 198
 199         writel(addr, siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
 200 }
 201
 202 static int i2c_sirfsoc_xfer_msg(struct sirfsoc_i2c *siic, struct i2c_msg *msg)
 203 {
 204         u32 regval = readl(siic->base + SIRFSOC_I2C_CTRL);
 205         /* timeout waiting for the xfer to finish or fail */
 206         int timeout = msecs_to_jiffies((msg->len + 1) * 50);
 207
 208         i2c_sirfsoc_set_address(siic, msg);
 209
 210         writel(regval | SIRFSOC_I2C_CMD_DONE_EN | SIRFSOC_I2C_ERR_INT_EN,
 211                 siic->base + SIRFSOC_I2C_CTRL);
 212         i2c_sirfsoc_queue_cmd(siic);
 213
 214         if (wait_for_completion_timeout(&siic->done, timeout) == 0) {
 215                 siic->err_status = SIRFSOC_I2C_ERR_TIMEOUT;
 216                 dev_err(&siic->adapter.dev, "Transfer timeout\n");
 217         }
 218
 219         writel(regval & ~(SIRFSOC_I2C_CMD_DONE_EN | SIRFSOC_I2C_ERR_INT_EN),
 220                 siic->base + SIRFSOC_I2C_CTRL);
 221         writel(0, siic->base + SIRFSOC_I2C_CMD_START);
 222
 223         /* i2c control doesn't response, reset it */
 224         if (siic->err_status == SIRFSOC_I2C_ERR_TIMEOUT) {
 225                 writel(readl(siic->base + SIRFSOC_I2C_CTRL) | SIRFSOC_I2C_RESET,
 226                         siic->base + SIRFSOC_I2C_CTRL);
 227                 while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
 228                         cpu_relax();
 229         }
 230         return siic->err_status ? -EAGAIN : 0;
 231 }
 232
 233 static u32 i2c_sirfsoc_func(struct i2c_adapter *adap)
 234 {
 235         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 236 }
 237
 238 static int i2c_sirfsoc_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 239         int num)
 240 {
 241         struct sirfsoc_i2c *siic = adap->algo_data;
 242         int i, ret;
 243
 244         clk_enable(siic->clk);
 245
 246         for (i = 0; i < num; i++) {
 247                 siic->buf = msgs[i].buf;
 248                 siic->msg_len = msgs[i].len;
 249                 siic->msg_read = !!(msgs[i].flags & I2C_M_RD);
 250                 siic->err_status = 0;
 251                 siic->cmd_ptr = 0;
 252                 siic->finished_len = 0;
 253                 siic->last = (i == (num - 1));
 254
 255                 ret = i2c_sirfsoc_xfer_msg(siic, &msgs[i]);
 256                 if (ret) {
 257                         clk_disable(siic->clk);
 258                         return ret;
 259                 }
 260         }
 261
 262         clk_disable(siic->clk);
 263         return num;
 264 }
 265
 266 /* I2C algorithms associated with this master controller driver */
 267 static const struct i2c_algorithm i2c_sirfsoc_algo = {
 268         .master_xfer = i2c_sirfsoc_xfer,
 269         .functionality = i2c_sirfsoc_func,
 270 };
 271
 272 static int i2c_sirfsoc_probe(struct platform_device *pdev)
 273 {
 274         struct sirfsoc_i2c *siic;
 275         struct i2c_adapter *adap;
 276         struct resource *mem_res;
 277         struct clk *clk;
 278         int bitrate;
 279         int ctrl_speed;
 280         int irq;
 281
 282         int err;
 283         u32 regval;
 284
 285         clk = clk_get(&pdev->dev, NULL);
 286         if (IS_ERR(clk)) {
 287                 err = PTR_ERR(clk);
 288                 dev_err(&pdev->dev, "Clock get failed\n");
 289                 goto err_get_clk;
 290         }
 291
 292         err = clk_prepare(clk);
 293         if (err) {
 294                 dev_err(&pdev->dev, "Clock prepare failed\n");
 295                 goto err_clk_prep;
 296         }
 297
 298         err = clk_enable(clk);
 299         if (err) {
 300                 dev_err(&pdev->dev, "Clock enable failed\n");
 301                 goto err_clk_en;
 302         }
 303
 304         ctrl_speed = clk_get_rate(clk);
 305
 306         siic = devm_kzalloc(&pdev->dev, sizeof(*siic), GFP_KERNEL);
 307         if (!siic) {
 308                 err = -ENOMEM;
 309                 goto out;
 310         }
 311         adap = &siic->adapter;
 312         adap->class = I2C_CLASS_DEPRECATED;
 313
 314         mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 315         siic->base = devm_ioremap_resource(&pdev->dev, mem_res);
 316         if (IS_ERR(siic->base)) {
 317                 err = PTR_ERR(siic->base);
 318                 goto out;
 319         }
 320
 321         irq = platform_get_irq(pdev, 0);
 322         if (irq < 0) {
 323                 err = irq;
 324                 goto out;
 325         }
 326         err = devm_request_irq(&pdev->dev, irq, i2c_sirfsoc_irq, 0,
 327                 dev_name(&pdev->dev), siic);
 328         if (err)
 329                 goto out;
 330
 331         adap->algo = &i2c_sirfsoc_algo;
 332         adap->algo_data = siic;
 333         adap->retries = 3;
 334
 335         adap->dev.of_node = pdev->dev.of_node;
 336         adap->dev.parent = &pdev->dev;
 337         adap->nr = pdev->id;
 338
 339         strlcpy(adap->name, "sirfsoc-i2c", sizeof(adap->name));
 340
 341         platform_set_drvdata(pdev, adap);
 342         init_completion(&siic->done);
 343
 344         /* Controller initialisation */
 345
 346         writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);
 347         while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
 348                 cpu_relax();
 349         writel(SIRFSOC_I2C_CORE_EN | SIRFSOC_I2C_MASTER_MODE,
 350                 siic->base + SIRFSOC_I2C_CTRL);
 351
 352         siic->clk = clk;
 353
 354         err = of_property_read_u32(pdev->dev.of_node,
 355                 "clock-frequency", &bitrate);
 356         if (err < 0)
 357                 bitrate = SIRFSOC_I2C_DEFAULT_SPEED;
 358
 359         /*
 360          * Due to some hardware design issues, we need to tune the formula.
 361          * Since i2c is open drain interface that allows the slave to
 362          * stall the transaction by holding the SCL line at '0', the RTL
 363          * implementation is waiting for SCL feedback from the pin after
 364          * setting it to High-Z ('1'). This wait adds to the high-time
 365          * interval counter few cycles of the input synchronization
 366          * (depending on the SCL_FILTER_REG field), and also the time it
 367          * takes for the board pull-up resistor to rise the SCL line.
 368          * For slow SCL settings these additions are negligible,
 369          * but they start to affect the speed when clock is set to faster
 370          * frequencies.
 371          * Through the actual tests, use the different user_div value(which
 372          * in the divider formula 'Fio / (Fi2c * user_div)') to adapt
 373          * the different ranges of i2c bus clock frequency, to make the SCL
 374          * more accurate.
 375          */
 376         if (bitrate <= 30000)
 377                 regval = ctrl_speed / (bitrate * 5);
 378         else if (bitrate > 30000 && bitrate <= 280000)
 379                 regval = (2 * ctrl_speed) / (bitrate * 11);
 380         else
 381                 regval = ctrl_speed / (bitrate * 6);
 382
 383         writel(regval, siic->base + SIRFSOC_I2C_CLK_CTRL);
 384         if (regval > 0xFF)
 385                 writel(0xFF, siic->base + SIRFSOC_I2C_SDA_DELAY);
 386         else
 387                 writel(regval, siic->base + SIRFSOC_I2C_SDA_DELAY);
 388
 389         err = i2c_add_numbered_adapter(adap);
 390         if (err < 0)
 391                 goto out;
 392
 393         clk_disable(clk);
 394
 395         dev_info(&pdev->dev, " I2C adapter ready to operate\n");
 396
 397         return 0;
 398
 399 out:
 400         clk_disable(clk);
 401 err_clk_en:
 402         clk_unprepare(clk);
 403 err_clk_prep:
 404         clk_put(clk);
 405 err_get_clk:
 406         return err;
 407 }
 408
 409 static int i2c_sirfsoc_remove(struct platform_device *pdev)
 410 {
 411         struct i2c_adapter *adapter = platform_get_drvdata(pdev);
 412         struct sirfsoc_i2c *siic = adapter->algo_data;
 413
 414         writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);
 415         i2c_del_adapter(adapter);
 416         clk_unprepare(siic->clk);
 417         clk_put(siic->clk);
 418         return 0;
 419 }
 420
 421 #ifdef CONFIG_PM
 422 static int i2c_sirfsoc_suspend(struct device *dev)
 423 {
 424         struct i2c_adapter *adapter = dev_get_drvdata(dev);
 425         struct sirfsoc_i2c *siic = adapter->algo_data;
 426
 427         clk_enable(siic->clk);
 428         siic->sda_delay = readl(siic->base + SIRFSOC_I2C_SDA_DELAY);
 429         siic->clk_div = readl(siic->base + SIRFSOC_I2C_CLK_CTRL);
 430         clk_disable(siic->clk);
 431         return 0;
 432 }
 433
 434 static int i2c_sirfsoc_resume(struct device *dev)
 435 {
 436         struct i2c_adapter *adapter = dev_get_drvdata(dev);
 437         struct sirfsoc_i2c *siic = adapter->algo_data;
 438
 439         clk_enable(siic->clk);
 440         writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);
 441         while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
 442                 cpu_relax();
 443         writel(SIRFSOC_I2C_CORE_EN | SIRFSOC_I2C_MASTER_MODE,
 444                 siic->base + SIRFSOC_I2C_CTRL);
 445         writel(siic->clk_div, siic->base + SIRFSOC_I2C_CLK_CTRL);
 446         writel(siic->sda_delay, siic->base + SIRFSOC_I2C_SDA_DELAY);
 447         clk_disable(siic->clk);
 448         return 0;
 449 }
 450
 451 static const struct dev_pm_ops i2c_sirfsoc_pm_ops = {
 452         .suspend = i2c_sirfsoc_suspend,
 453         .resume = i2c_sirfsoc_resume,
 454 };
 455 #endif
 456
 457 static const struct of_device_id sirfsoc_i2c_of_match[] = {
 458         { .compatible = "sirf,prima2-i2c", },
 459         {},
 460 };
 461 MODULE_DEVICE_TABLE(of, sirfsoc_i2c_of_match);
 462
 463 static struct platform_driver i2c_sirfsoc_driver = {
 464         .driver = {
 465                 .name = "sirfsoc_i2c",
 466 #ifdef CONFIG_PM
 467                 .pm = &i2c_sirfsoc_pm_ops,
 468 #endif
 469                 .of_match_table = sirfsoc_i2c_of_match,
 470         },
 471         .probe = i2c_sirfsoc_probe,
 472         .remove = i2c_sirfsoc_remove,
 473 };
 474 module_platform_driver(i2c_sirfsoc_driver);
 475
 476 MODULE_DESCRIPTION("SiRF SoC I2C master controller driver");
 477 MODULE_AUTHOR("Zhiwu Song <Zhiwu.Song@csr.com>, "
 478         "Xiangzhen Ye <Xiangzhen.Ye@csr.com>");
 479 MODULE_LICENSE("GPL v2");