drivers/i2c/busses/i2c-zx2967.c

   1 /*
   2  * Copyright (C) 2017 Sanechips Technology Co., Ltd.
   3  * Copyright 2017 Linaro Ltd.
   4  *
   5  * Author: Baoyou Xie <baoyou.xie@linaro.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/clk.h>
  13 #include <linux/i2c.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/io.h>
  16 #include <linux/module.h>
  17 #include <linux/platform_device.h>
  18
  19 #define REG_CMD                         0x04
  20 #define REG_DEVADDR_H                   0x0C
  21 #define REG_DEVADDR_L                   0x10
  22 #define REG_CLK_DIV_FS                  0x14
  23 #define REG_CLK_DIV_HS                  0x18
  24 #define REG_WRCONF                      0x1C
  25 #define REG_RDCONF                      0x20
  26 #define REG_DATA                        0x24
  27 #define REG_STAT                        0x28
  28
  29 #define I2C_STOP                        0
  30 #define I2C_MASTER                      BIT(0)
  31 #define I2C_ADDR_MODE_TEN               BIT(1)
  32 #define I2C_IRQ_MSK_ENABLE              BIT(3)
  33 #define I2C_RW_READ                     BIT(4)
  34 #define I2C_CMB_RW_EN                   BIT(5)
  35 #define I2C_START                       BIT(6)
  36
  37 #define I2C_ADDR_LOW_MASK               GENMASK(6, 0)
  38 #define I2C_ADDR_LOW_SHIFT              0
  39 #define I2C_ADDR_HI_MASK                GENMASK(2, 0)
  40 #define I2C_ADDR_HI_SHIFT               7
  41
  42 #define I2C_WFIFO_RESET                 BIT(7)
  43 #define I2C_RFIFO_RESET                 BIT(7)
  44
  45 #define I2C_IRQ_ACK_CLEAR               BIT(7)
  46 #define I2C_INT_MASK                    GENMASK(6, 0)
  47
  48 #define I2C_TRANS_DONE                  BIT(0)
  49 #define I2C_SR_EDEVICE                  BIT(1)
  50 #define I2C_SR_EDATA                    BIT(2)
  51
  52 #define I2C_FIFO_MAX                    16
  53
  54 #define I2C_TIMEOUT                     msecs_to_jiffies(1000)
  55
  56 #define DEV(i2c)                        ((i2c)->adap.dev.parent)
  57
  58 struct zx2967_i2c {
  59         struct i2c_adapter      adap;
  60         struct clk              *clk;
  61         struct completion       complete;
  62         u32                     clk_freq;
  63         void __iomem            *reg_base;
  64         size_t                  residue;
  65         int                     irq;
  66         int                     msg_rd;
  67         u8                      *cur_trans;
  68         u8                      access_cnt;
  69         bool                    is_suspended;
  70         int                     error;
  71 };
  72
  73 static void zx2967_i2c_writel(struct zx2967_i2c *i2c,
  74                               u32 val, unsigned long reg)
  75 {
  76         writel_relaxed(val, i2c->reg_base + reg);
  77 }
  78
  79 static u32 zx2967_i2c_readl(struct zx2967_i2c *i2c, unsigned long reg)
  80 {
  81         return readl_relaxed(i2c->reg_base + reg);
  82 }
  83
  84 static void zx2967_i2c_writesb(struct zx2967_i2c *i2c,
  85                                void *data, unsigned long reg, int len)
  86 {
  87         writesb(i2c->reg_base + reg, data, len);
  88 }
  89
  90 static void zx2967_i2c_readsb(struct zx2967_i2c *i2c,
  91                               void *data, unsigned long reg, int len)
  92 {
  93         readsb(i2c->reg_base + reg, data, len);
  94 }
  95
  96 static void zx2967_i2c_start_ctrl(struct zx2967_i2c *i2c)
  97 {
  98         u32 status;
  99         u32 ctl;
 100
 101         status = zx2967_i2c_readl(i2c, REG_STAT);
 102         status |= I2C_IRQ_ACK_CLEAR;
 103         zx2967_i2c_writel(i2c, status, REG_STAT);
 104
 105         ctl = zx2967_i2c_readl(i2c, REG_CMD);
 106         if (i2c->msg_rd)
 107                 ctl |= I2C_RW_READ;
 108         else
 109                 ctl &= ~I2C_RW_READ;
 110         ctl &= ~I2C_CMB_RW_EN;
 111         ctl |= I2C_START;
 112         zx2967_i2c_writel(i2c, ctl, REG_CMD);
 113 }
 114
 115 static void zx2967_i2c_flush_fifos(struct zx2967_i2c *i2c)
 116 {
 117         u32 offset;
 118         u32 val;
 119
 120         if (i2c->msg_rd) {
 121                 offset = REG_RDCONF;
 122                 val = I2C_RFIFO_RESET;
 123         } else {
 124                 offset = REG_WRCONF;
 125                 val = I2C_WFIFO_RESET;
 126         }
 127
 128         val |= zx2967_i2c_readl(i2c, offset);
 129         zx2967_i2c_writel(i2c, val, offset);
 130 }
 131
 132 static int zx2967_i2c_empty_rx_fifo(struct zx2967_i2c *i2c, u32 size)
 133 {
 134         u8 val[I2C_FIFO_MAX] = {0};
 135         int i;
 136
 137         if (size > I2C_FIFO_MAX) {
 138                 dev_err(DEV(i2c), "fifo size %d over the max value %d\n",
 139                         size, I2C_FIFO_MAX);
 140                 return -EINVAL;
 141         }
 142
 143         zx2967_i2c_readsb(i2c, val, REG_DATA, size);
 144         for (i = 0; i < size; i++) {
 145                 *i2c->cur_trans++ = val[i];
 146                 i2c->residue--;
 147         }
 148
 149         barrier();
 150
 151         return 0;
 152 }
 153
 154 static int zx2967_i2c_fill_tx_fifo(struct zx2967_i2c *i2c)
 155 {
 156         size_t residue = i2c->residue;
 157         u8 *buf = i2c->cur_trans;
 158
 159         if (residue == 0) {
 160                 dev_err(DEV(i2c), "residue is %d\n", (int)residue);
 161                 return -EINVAL;
 162         }
 163
 164         if (residue <= I2C_FIFO_MAX) {
 165                 zx2967_i2c_writesb(i2c, buf, REG_DATA, residue);
 166
 167                 /* Again update before writing to FIFO to make sure isr sees. */
 168                 i2c->residue = 0;
 169                 i2c->cur_trans = NULL;
 170         } else {
 171                 zx2967_i2c_writesb(i2c, buf, REG_DATA, I2C_FIFO_MAX);
 172                 i2c->residue -= I2C_FIFO_MAX;
 173                 i2c->cur_trans += I2C_FIFO_MAX;
 174         }
 175
 176         barrier();
 177
 178         return 0;
 179 }
 180
 181 static int zx2967_i2c_reset_hardware(struct zx2967_i2c *i2c)
 182 {
 183         u32 val;
 184         u32 clk_div;
 185
 186         val = I2C_MASTER | I2C_IRQ_MSK_ENABLE;
 187         zx2967_i2c_writel(i2c, val, REG_CMD);
 188
 189         clk_div = clk_get_rate(i2c->clk) / i2c->clk_freq - 1;
 190         zx2967_i2c_writel(i2c, clk_div, REG_CLK_DIV_FS);
 191         zx2967_i2c_writel(i2c, clk_div, REG_CLK_DIV_HS);
 192
 193         zx2967_i2c_writel(i2c, I2C_FIFO_MAX - 1, REG_WRCONF);
 194         zx2967_i2c_writel(i2c, I2C_FIFO_MAX - 1, REG_RDCONF);
 195         zx2967_i2c_writel(i2c, 1, REG_RDCONF);
 196
 197         zx2967_i2c_flush_fifos(i2c);
 198
 199         return 0;
 200 }
 201
 202 static void zx2967_i2c_isr_clr(struct zx2967_i2c *i2c)
 203 {
 204         u32 status;
 205
 206         status = zx2967_i2c_readl(i2c, REG_STAT);
 207         status |= I2C_IRQ_ACK_CLEAR;
 208         zx2967_i2c_writel(i2c, status, REG_STAT);
 209 }
 210
 211 static irqreturn_t zx2967_i2c_isr(int irq, void *dev_id)
 212 {
 213         u32 status;
 214         struct zx2967_i2c *i2c = (struct zx2967_i2c *)dev_id;
 215
 216         status = zx2967_i2c_readl(i2c, REG_STAT) & I2C_INT_MASK;
 217         zx2967_i2c_isr_clr(i2c);
 218
 219         if (status & I2C_SR_EDEVICE)
 220                 i2c->error = -ENXIO;
 221         else if (status & I2C_SR_EDATA)
 222                 i2c->error = -EIO;
 223         else if (status & I2C_TRANS_DONE)
 224                 i2c->error = 0;
 225         else
 226                 goto done;
 227
 228         complete(&i2c->complete);
 229 done:
 230         return IRQ_HANDLED;
 231 }
 232
 233 static void zx2967_set_addr(struct zx2967_i2c *i2c, u16 addr)
 234 {
 235         u16 val;
 236
 237         val = (addr >> I2C_ADDR_LOW_SHIFT) & I2C_ADDR_LOW_MASK;
 238         zx2967_i2c_writel(i2c, val, REG_DEVADDR_L);
 239
 240         val = (addr >> I2C_ADDR_HI_SHIFT) & I2C_ADDR_HI_MASK;
 241         zx2967_i2c_writel(i2c, val, REG_DEVADDR_H);
 242         if (val)
 243                 val = zx2967_i2c_readl(i2c, REG_CMD) | I2C_ADDR_MODE_TEN;
 244         else
 245                 val = zx2967_i2c_readl(i2c, REG_CMD) & ~I2C_ADDR_MODE_TEN;
 246         zx2967_i2c_writel(i2c, val, REG_CMD);
 247 }
 248
 249 static int zx2967_i2c_xfer_bytes(struct zx2967_i2c *i2c, u32 bytes)
 250 {
 251         unsigned long time_left;
 252         int rd = i2c->msg_rd;
 253         int ret;
 254
 255         reinit_completion(&i2c->complete);
 256
 257         if (rd) {
 258                 zx2967_i2c_writel(i2c, bytes - 1, REG_RDCONF);
 259         } else {
 260                 ret = zx2967_i2c_fill_tx_fifo(i2c);
 261                 if (ret)
 262                         return ret;
 263         }
 264
 265         zx2967_i2c_start_ctrl(i2c);
 266
 267         time_left = wait_for_completion_timeout(&i2c->complete,
 268                                                 I2C_TIMEOUT);
 269         if (time_left == 0)
 270                 return -ETIMEDOUT;
 271
 272         if (i2c->error)
 273                 return i2c->error;
 274
 275         return rd ? zx2967_i2c_empty_rx_fifo(i2c, bytes) : 0;
 276 }
 277
 278 static int zx2967_i2c_xfer_msg(struct zx2967_i2c *i2c,
 279                                struct i2c_msg *msg)
 280 {
 281         int ret;
 282         int i;
 283
 284         if (msg->len == 0)
 285                 return -EINVAL;
 286
 287         zx2967_i2c_flush_fifos(i2c);
 288
 289         i2c->cur_trans = msg->buf;
 290         i2c->residue = msg->len;
 291         i2c->access_cnt = msg->len / I2C_FIFO_MAX;
 292         i2c->msg_rd = msg->flags & I2C_M_RD;
 293
 294         for (i = 0; i < i2c->access_cnt; i++) {
 295                 ret = zx2967_i2c_xfer_bytes(i2c, I2C_FIFO_MAX);
 296                 if (ret)
 297                         return ret;
 298         }
 299
 300         if (i2c->residue > 0) {
 301                 ret = zx2967_i2c_xfer_bytes(i2c, i2c->residue);
 302                 if (ret)
 303                         return ret;
 304         }
 305
 306         i2c->residue = 0;
 307         i2c->access_cnt = 0;
 308
 309         return 0;
 310 }
 311
 312 static int zx2967_i2c_xfer(struct i2c_adapter *adap,
 313                            struct i2c_msg *msgs, int num)
 314 {
 315         struct zx2967_i2c *i2c = i2c_get_adapdata(adap);
 316         int ret;
 317         int i;
 318
 319         if (i2c->is_suspended)
 320                 return -EBUSY;
 321
 322         zx2967_set_addr(i2c, msgs->addr);
 323
 324         for (i = 0; i < num; i++) {
 325                 ret = zx2967_i2c_xfer_msg(i2c, &msgs[i]);
 326                 if (ret)
 327                         return ret;
 328         }
 329
 330         return num;
 331 }
 332
 333 static void
 334 zx2967_smbus_xfer_prepare(struct zx2967_i2c *i2c, u16 addr,
 335                           char read_write, u8 command, int size,
 336                           union i2c_smbus_data *data)
 337 {
 338         u32 val;
 339
 340         val = zx2967_i2c_readl(i2c, REG_RDCONF);
 341         val |= I2C_RFIFO_RESET;
 342         zx2967_i2c_writel(i2c, val, REG_RDCONF);
 343         zx2967_set_addr(i2c, addr);
 344         val = zx2967_i2c_readl(i2c, REG_CMD);
 345         val &= ~I2C_RW_READ;
 346         zx2967_i2c_writel(i2c, val, REG_CMD);
 347
 348         switch (size) {
 349         case I2C_SMBUS_BYTE:
 350                 zx2967_i2c_writel(i2c, command, REG_DATA);
 351                 break;
 352         case I2C_SMBUS_BYTE_DATA:
 353                 zx2967_i2c_writel(i2c, command, REG_DATA);
 354                 if (read_write == I2C_SMBUS_WRITE)
 355                         zx2967_i2c_writel(i2c, data->byte, REG_DATA);
 356                 break;
 357         case I2C_SMBUS_WORD_DATA:
 358                 zx2967_i2c_writel(i2c, command, REG_DATA);
 359                 if (read_write == I2C_SMBUS_WRITE) {
 360                         zx2967_i2c_writel(i2c, (data->word >> 8), REG_DATA);
 361                         zx2967_i2c_writel(i2c, (data->word & 0xff),
 362                                           REG_DATA);
 363                 }
 364                 break;
 365         }
 366 }
 367
 368 static int zx2967_smbus_xfer_read(struct zx2967_i2c *i2c, int size,
 369                                   union i2c_smbus_data *data)
 370 {
 371         unsigned long time_left;
 372         u8 buf[2];
 373         u32 val;
 374
 375         reinit_completion(&i2c->complete);
 376
 377         val = zx2967_i2c_readl(i2c, REG_CMD);
 378         val |= I2C_CMB_RW_EN;
 379         zx2967_i2c_writel(i2c, val, REG_CMD);
 380
 381         val = zx2967_i2c_readl(i2c, REG_CMD);
 382         val |= I2C_START;
 383         zx2967_i2c_writel(i2c, val, REG_CMD);
 384
 385         time_left = wait_for_completion_timeout(&i2c->complete,
 386                                                 I2C_TIMEOUT);
 387         if (time_left == 0)
 388                 return -ETIMEDOUT;
 389
 390         if (i2c->error)
 391                 return i2c->error;
 392
 393         switch (size) {
 394         case I2C_SMBUS_BYTE:
 395         case I2C_SMBUS_BYTE_DATA:
 396                 val = zx2967_i2c_readl(i2c, REG_DATA);
 397                 data->byte = val;
 398                 break;
 399         case I2C_SMBUS_WORD_DATA:
 400         case I2C_SMBUS_PROC_CALL:
 401                 buf[0] = zx2967_i2c_readl(i2c, REG_DATA);
 402                 buf[1] = zx2967_i2c_readl(i2c, REG_DATA);
 403                 data->word = (buf[0] << 8) | buf[1];
 404                 break;
 405         default:
 406                 return -EOPNOTSUPP;
 407         }
 408
 409         return 0;
 410 }
 411
 412 static int zx2967_smbus_xfer_write(struct zx2967_i2c *i2c)
 413 {
 414         unsigned long time_left;
 415         u32 val;
 416
 417         reinit_completion(&i2c->complete);
 418         val = zx2967_i2c_readl(i2c, REG_CMD);
 419         val |= I2C_START;
 420         zx2967_i2c_writel(i2c, val, REG_CMD);
 421
 422         time_left = wait_for_completion_timeout(&i2c->complete,
 423                                                 I2C_TIMEOUT);
 424         if (time_left == 0)
 425                 return -ETIMEDOUT;
 426
 427         if (i2c->error)
 428                 return i2c->error;
 429
 430         return 0;
 431 }
 432
 433 static int zx2967_smbus_xfer(struct i2c_adapter *adap, u16 addr,
 434                              unsigned short flags, char read_write,
 435                              u8 command, int size, union i2c_smbus_data *data)
 436 {
 437         struct zx2967_i2c *i2c = i2c_get_adapdata(adap);
 438
 439         if (size == I2C_SMBUS_QUICK)
 440                 read_write = I2C_SMBUS_WRITE;
 441
 442         switch (size) {
 443         case I2C_SMBUS_QUICK:
 444         case I2C_SMBUS_BYTE:
 445         case I2C_SMBUS_BYTE_DATA:
 446         case I2C_SMBUS_WORD_DATA:
 447                 zx2967_smbus_xfer_prepare(i2c, addr, read_write,
 448                                           command, size, data);
 449                 break;
 450         default:
 451                 return -EOPNOTSUPP;
 452         }
 453
 454         if (read_write == I2C_SMBUS_READ)
 455                 return zx2967_smbus_xfer_read(i2c, size, data);
 456
 457         return zx2967_smbus_xfer_write(i2c);
 458 }
 459
 460 static u32 zx2967_i2c_func(struct i2c_adapter *adap)
 461 {
 462         return I2C_FUNC_I2C |
 463                I2C_FUNC_SMBUS_QUICK |
 464                I2C_FUNC_SMBUS_BYTE |
 465                I2C_FUNC_SMBUS_BYTE_DATA |
 466                I2C_FUNC_SMBUS_WORD_DATA |
 467                I2C_FUNC_SMBUS_BLOCK_DATA |
 468                I2C_FUNC_SMBUS_PROC_CALL |
 469                I2C_FUNC_SMBUS_I2C_BLOCK;
 470 }
 471
 472 static int __maybe_unused zx2967_i2c_suspend(struct device *dev)
 473 {
 474         struct zx2967_i2c *i2c = dev_get_drvdata(dev);
 475
 476         i2c->is_suspended = true;
 477         clk_disable_unprepare(i2c->clk);
 478
 479         return 0;
 480 }
 481
 482 static int __maybe_unused zx2967_i2c_resume(struct device *dev)
 483 {
 484         struct zx2967_i2c *i2c = dev_get_drvdata(dev);
 485
 486         i2c->is_suspended = false;
 487         clk_prepare_enable(i2c->clk);
 488
 489         return 0;
 490 }
 491
 492 static SIMPLE_DEV_PM_OPS(zx2967_i2c_dev_pm_ops,
 493                          zx2967_i2c_suspend, zx2967_i2c_resume);
 494
 495 static const struct i2c_algorithm zx2967_i2c_algo = {
 496         .master_xfer = zx2967_i2c_xfer,
 497         .smbus_xfer = zx2967_smbus_xfer,
 498         .functionality = zx2967_i2c_func,
 499 };
 500
 501 static const struct of_device_id zx2967_i2c_of_match[] = {
 502         { .compatible = "zte,zx296718-i2c", },
 503         { },
 504 };
 505 MODULE_DEVICE_TABLE(of, zx2967_i2c_of_match);
 506
 507 static int zx2967_i2c_probe(struct platform_device *pdev)
 508 {
 509         struct zx2967_i2c *i2c;
 510         void __iomem *reg_base;
 511         struct resource *res;
 512         struct clk *clk;
 513         int ret;
 514
 515         i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
 516         if (!i2c)
 517                 return -ENOMEM;
 518
 519         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 520         reg_base = devm_ioremap_resource(&pdev->dev, res);
 521         if (IS_ERR(reg_base))
 522                 return PTR_ERR(reg_base);
 523
 524         clk = devm_clk_get(&pdev->dev, NULL);
 525         if (IS_ERR(clk)) {
 526                 dev_err(&pdev->dev, "missing controller clock");
 527                 return PTR_ERR(clk);
 528         }
 529
 530         ret = clk_prepare_enable(clk);
 531         if (ret) {
 532                 dev_err(&pdev->dev, "failed to enable i2c_clk\n");
 533                 return ret;
 534         }
 535
 536         ret = device_property_read_u32(&pdev->dev, "clock-frequency",
 537                                        &i2c->clk_freq);
 538         if (ret) {
 539                 dev_err(&pdev->dev, "missing clock-frequency");
 540                 return ret;
 541         }
 542
 543         ret = platform_get_irq(pdev, 0);
 544         if (ret < 0)
 545                 return ret;
 546
 547         i2c->irq = ret;
 548         i2c->reg_base = reg_base;
 549         i2c->clk = clk;
 550
 551         init_completion(&i2c->complete);
 552         platform_set_drvdata(pdev, i2c);
 553
 554         ret = zx2967_i2c_reset_hardware(i2c);
 555         if (ret) {
 556                 dev_err(&pdev->dev, "failed to initialize i2c controller\n");
 557                 goto err_clk_unprepare;
 558         }
 559
 560         ret = devm_request_irq(&pdev->dev, i2c->irq,
 561                         zx2967_i2c_isr, 0, dev_name(&pdev->dev), i2c);
 562         if (ret) {
 563                 dev_err(&pdev->dev, "failed to request irq %i\n", i2c->irq);
 564                 goto err_clk_unprepare;
 565         }
 566
 567         i2c_set_adapdata(&i2c->adap, i2c);
 568         strlcpy(i2c->adap.name, "zx2967 i2c adapter",
 569                 sizeof(i2c->adap.name));
 570         i2c->adap.algo = &zx2967_i2c_algo;
 571         i2c->adap.nr = pdev->id;
 572         i2c->adap.dev.parent = &pdev->dev;
 573         i2c->adap.dev.of_node = pdev->dev.of_node;
 574
 575         ret = i2c_add_numbered_adapter(&i2c->adap);
 576         if (ret)
 577                 goto err_clk_unprepare;
 578
 579         return 0;
 580
 581 err_clk_unprepare:
 582         clk_disable_unprepare(i2c->clk);
 583         return ret;
 584 }
 585
 586 static int zx2967_i2c_remove(struct platform_device *pdev)
 587 {
 588         struct zx2967_i2c *i2c = platform_get_drvdata(pdev);
 589
 590         i2c_del_adapter(&i2c->adap);
 591         clk_disable_unprepare(i2c->clk);
 592
 593         return 0;
 594 }
 595
 596 static struct platform_driver zx2967_i2c_driver = {
 597         .probe  = zx2967_i2c_probe,
 598         .remove = zx2967_i2c_remove,
 599         .driver = {
 600                 .name  = "zx2967_i2c",
 601                 .of_match_table = zx2967_i2c_of_match,
 602                 .pm = &zx2967_i2c_dev_pm_ops,
 603         },
 604 };
 605 module_platform_driver(zx2967_i2c_driver);
 606
 607 MODULE_AUTHOR("Baoyou Xie <baoyou.xie@linaro.org>");
 608 MODULE_DESCRIPTION("ZTE ZX2967 I2C Bus Controller driver");
 609 MODULE_LICENSE("GPL v2");