drivers/i2c/busses/i2c-meson.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * I2C bus driver for Amlogic Meson SoCs
   4  *
   5  * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com>
   6  */
   7
   8 #include <linux/bitfield.h>
   9 #include <linux/clk.h>
  10 #include <linux/completion.h>
  11 #include <linux/i2c.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/io.h>
  14 #include <linux/iopoll.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/of_device.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/types.h>
  21
  22 /* Meson I2C register map */
  23 #define REG_CTRL                0x00
  24 #define REG_SLAVE_ADDR          0x04
  25 #define REG_TOK_LIST0           0x08
  26 #define REG_TOK_LIST1           0x0c
  27 #define REG_TOK_WDATA0          0x10
  28 #define REG_TOK_WDATA1          0x14
  29 #define REG_TOK_RDATA0          0x18
  30 #define REG_TOK_RDATA1          0x1c
  31
  32 /* Control register fields */
  33 #define REG_CTRL_START          BIT(0)
  34 #define REG_CTRL_ACK_IGNORE     BIT(1)
  35 #define REG_CTRL_STATUS         BIT(2)
  36 #define REG_CTRL_ERROR          BIT(3)
  37 #define REG_CTRL_CLKDIV         GENMASK(21, 12)
  38 #define REG_CTRL_CLKDIVEXT      GENMASK(29, 28)
  39
  40 #define REG_SLV_ADDR            GENMASK(7, 0)
  41 #define REG_SLV_SDA_FILTER      GENMASK(10, 8)
  42 #define REG_SLV_SCL_FILTER      GENMASK(13, 11)
  43 #define REG_SLV_SCL_LOW         GENMASK(27, 16)
  44 #define REG_SLV_SCL_LOW_EN      BIT(28)
  45
  46 #define I2C_TIMEOUT_MS          500
  47 #define FILTER_DELAY            15
  48
  49 enum {
  50         TOKEN_END = 0,
  51         TOKEN_START,
  52         TOKEN_SLAVE_ADDR_WRITE,
  53         TOKEN_SLAVE_ADDR_READ,
  54         TOKEN_DATA,
  55         TOKEN_DATA_LAST,
  56         TOKEN_STOP,
  57 };
  58
  59 enum {
  60         STATE_IDLE,
  61         STATE_READ,
  62         STATE_WRITE,
  63 };
  64
  65 struct meson_i2c_data {
  66         unsigned char div_factor;
  67 };
  68
  69 /**
  70  * struct meson_i2c - Meson I2C device private data
  71  *
  72  * @adap:       I2C adapter instance
  73  * @dev:        Pointer to device structure
  74  * @regs:       Base address of the device memory mapped registers
  75  * @clk:        Pointer to clock structure
  76  * @msg:        Pointer to the current I2C message
  77  * @state:      Current state in the driver state machine
  78  * @last:       Flag set for the last message in the transfer
  79  * @count:      Number of bytes to be sent/received in current transfer
  80  * @pos:        Current position in the send/receive buffer
  81  * @error:      Flag set when an error is received
  82  * @lock:       To avoid race conditions between irq handler and xfer code
  83  * @done:       Completion used to wait for transfer termination
  84  * @tokens:     Sequence of tokens to be written to the device
  85  * @num_tokens: Number of tokens
  86  * @data:       Pointer to the controlller's platform data
  87  */
  88 struct meson_i2c {
  89         struct i2c_adapter      adap;
  90         struct device           *dev;
  91         void __iomem            *regs;
  92         struct clk              *clk;
  93
  94         struct i2c_msg          *msg;
  95         int                     state;
  96         bool                    last;
  97         int                     count;
  98         int                     pos;
  99         int                     error;
 100
 101         spinlock_t              lock;
 102         struct completion       done;
 103         u32                     tokens[2];
 104         int                     num_tokens;
 105
 106         const struct meson_i2c_data *data;
 107 };
 108
 109 static void meson_i2c_set_mask(struct meson_i2c *i2c, int reg, u32 mask,
 110                                u32 val)
 111 {
 112         u32 data;
 113
 114         data = readl(i2c->regs + reg);
 115         data &= ~mask;
 116         data |= val & mask;
 117         writel(data, i2c->regs + reg);
 118 }
 119
 120 static void meson_i2c_reset_tokens(struct meson_i2c *i2c)
 121 {
 122         i2c->tokens[0] = 0;
 123         i2c->tokens[1] = 0;
 124         i2c->num_tokens = 0;
 125 }
 126
 127 static void meson_i2c_add_token(struct meson_i2c *i2c, int token)
 128 {
 129         if (i2c->num_tokens < 8)
 130                 i2c->tokens[0] |= (token & 0xf) << (i2c->num_tokens * 4);
 131         else
 132                 i2c->tokens[1] |= (token & 0xf) << ((i2c->num_tokens % 8) * 4);
 133
 134         i2c->num_tokens++;
 135 }
 136
 137 static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq)
 138 {
 139         unsigned long clk_rate = clk_get_rate(i2c->clk);
 140         unsigned int div;
 141
 142         div = DIV_ROUND_UP(clk_rate, freq);
 143         div -= FILTER_DELAY;
 144         div = DIV_ROUND_UP(div, i2c->data->div_factor);
 145
 146         /* clock divider has 12 bits */
 147         if (div > GENMASK(11, 0)) {
 148                 dev_err(i2c->dev, "requested bus frequency too low\n");
 149                 div = GENMASK(11, 0);
 150         }
 151
 152         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV,
 153                            FIELD_PREP(REG_CTRL_CLKDIV, div & GENMASK(9, 0)));
 154
 155         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT,
 156                            FIELD_PREP(REG_CTRL_CLKDIVEXT, div >> 10));
 157
 158         /* Disable HIGH/LOW mode */
 159         meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_SCL_LOW_EN, 0);
 160
 161         dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
 162                 clk_rate, freq, div);
 163 }
 164
 165 static void meson_i2c_get_data(struct meson_i2c *i2c, char *buf, int len)
 166 {
 167         u32 rdata0, rdata1;
 168         int i;
 169
 170         rdata0 = readl(i2c->regs + REG_TOK_RDATA0);
 171         rdata1 = readl(i2c->regs + REG_TOK_RDATA1);
 172
 173         dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
 174                 rdata0, rdata1, len);
 175
 176         for (i = 0; i < min(4, len); i++)
 177                 *buf++ = (rdata0 >> i * 8) & 0xff;
 178
 179         for (i = 4; i < min(8, len); i++)
 180                 *buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
 181 }
 182
 183 static void meson_i2c_put_data(struct meson_i2c *i2c, char *buf, int len)
 184 {
 185         u32 wdata0 = 0, wdata1 = 0;
 186         int i;
 187
 188         for (i = 0; i < min(4, len); i++)
 189                 wdata0 |= *buf++ << (i * 8);
 190
 191         for (i = 4; i < min(8, len); i++)
 192                 wdata1 |= *buf++ << ((i - 4) * 8);
 193
 194         writel(wdata0, i2c->regs + REG_TOK_WDATA0);
 195         writel(wdata1, i2c->regs + REG_TOK_WDATA1);
 196
 197         dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
 198                 wdata0, wdata1, len);
 199 }
 200
 201 static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
 202 {
 203         bool write = !(i2c->msg->flags & I2C_M_RD);
 204         int i;
 205
 206         i2c->count = min(i2c->msg->len - i2c->pos, 8);
 207
 208         for (i = 0; i < i2c->count - 1; i++)
 209                 meson_i2c_add_token(i2c, TOKEN_DATA);
 210
 211         if (i2c->count) {
 212                 if (write || i2c->pos + i2c->count < i2c->msg->len)
 213                         meson_i2c_add_token(i2c, TOKEN_DATA);
 214                 else
 215                         meson_i2c_add_token(i2c, TOKEN_DATA_LAST);
 216         }
 217
 218         if (write)
 219                 meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);
 220
 221         if (i2c->last && i2c->pos + i2c->count >= i2c->msg->len)
 222                 meson_i2c_add_token(i2c, TOKEN_STOP);
 223
 224         writel(i2c->tokens[0], i2c->regs + REG_TOK_LIST0);
 225         writel(i2c->tokens[1], i2c->regs + REG_TOK_LIST1);
 226 }
 227
 228 static void meson_i2c_transfer_complete(struct meson_i2c *i2c, u32 ctrl)
 229 {
 230         if (ctrl & REG_CTRL_ERROR) {
 231                 /*
 232                  * The bit is set when the IGNORE_NAK bit is cleared
 233                  * and the device didn't respond. In this case, the
 234                  * I2C controller automatically generates a STOP
 235                  * condition.
 236                  */
 237                 dev_dbg(i2c->dev, "error bit set\n");
 238                 i2c->error = -ENXIO;
 239                 i2c->state = STATE_IDLE;
 240         } else {
 241                 if (i2c->state == STATE_READ && i2c->count)
 242                         meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos,
 243                                            i2c->count);
 244
 245                 i2c->pos += i2c->count;
 246
 247                 if (i2c->pos >= i2c->msg->len)
 248                         i2c->state = STATE_IDLE;
 249         }
 250 }
 251
 252 static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
 253 {
 254         struct meson_i2c *i2c = dev_id;
 255         unsigned int ctrl;
 256
 257         spin_lock(&i2c->lock);
 258
 259         meson_i2c_reset_tokens(i2c);
 260         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
 261         ctrl = readl(i2c->regs + REG_CTRL);
 262
 263         dev_dbg(i2c->dev, "irq: state %d, pos %d, count %d, ctrl %08x\n",
 264                 i2c->state, i2c->pos, i2c->count, ctrl);
 265
 266         if (i2c->state == STATE_IDLE) {
 267                 spin_unlock(&i2c->lock);
 268                 return IRQ_NONE;
 269         }
 270
 271         meson_i2c_transfer_complete(i2c, ctrl);
 272
 273         if (i2c->state == STATE_IDLE) {
 274                 complete(&i2c->done);
 275                 goto out;
 276         }
 277
 278         /* Restart the processing */
 279         meson_i2c_prepare_xfer(i2c);
 280         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, REG_CTRL_START);
 281 out:
 282         spin_unlock(&i2c->lock);
 283
 284         return IRQ_HANDLED;
 285 }
 286
 287 static void meson_i2c_do_start(struct meson_i2c *i2c, struct i2c_msg *msg)
 288 {
 289         int token;
 290
 291         token = (msg->flags & I2C_M_RD) ? TOKEN_SLAVE_ADDR_READ :
 292                 TOKEN_SLAVE_ADDR_WRITE;
 293
 294
 295         meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_ADDR,
 296                            FIELD_PREP(REG_SLV_ADDR, msg->addr << 1));
 297
 298         meson_i2c_add_token(i2c, TOKEN_START);
 299         meson_i2c_add_token(i2c, token);
 300 }
 301
 302 static int meson_i2c_xfer_msg(struct meson_i2c *i2c, struct i2c_msg *msg,
 303                               int last, bool atomic)
 304 {
 305         unsigned long time_left, flags;
 306         int ret = 0;
 307         u32 ctrl;
 308
 309         i2c->msg = msg;
 310         i2c->last = last;
 311         i2c->pos = 0;
 312         i2c->count = 0;
 313         i2c->error = 0;
 314
 315         meson_i2c_reset_tokens(i2c);
 316
 317         flags = (msg->flags & I2C_M_IGNORE_NAK) ? REG_CTRL_ACK_IGNORE : 0;
 318         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_ACK_IGNORE, flags);
 319
 320         if (!(msg->flags & I2C_M_NOSTART))
 321                 meson_i2c_do_start(i2c, msg);
 322
 323         i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
 324         meson_i2c_prepare_xfer(i2c);
 325
 326         if (!atomic)
 327                 reinit_completion(&i2c->done);
 328
 329         /* Start the transfer */
 330         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, REG_CTRL_START);
 331
 332         if (atomic) {
 333                 ret = readl_poll_timeout_atomic(i2c->regs + REG_CTRL, ctrl,
 334                                                 !(ctrl & REG_CTRL_STATUS),
 335                                                 10, I2C_TIMEOUT_MS * 1000);
 336         } else {
 337                 time_left = msecs_to_jiffies(I2C_TIMEOUT_MS);
 338                 time_left = wait_for_completion_timeout(&i2c->done, time_left);
 339
 340                 if (!time_left)
 341                         ret = -ETIMEDOUT;
 342         }
 343
 344         /*
 345          * Protect access to i2c struct and registers from interrupt
 346          * handlers triggered by a transfer terminated after the
 347          * timeout period
 348          */
 349         spin_lock_irqsave(&i2c->lock, flags);
 350
 351         if (atomic && !ret)
 352                 meson_i2c_transfer_complete(i2c, ctrl);
 353
 354         /* Abort any active operation */
 355         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
 356
 357         if (ret)
 358                 i2c->state = STATE_IDLE;
 359
 360         if (i2c->error)
 361                 ret = i2c->error;
 362
 363         spin_unlock_irqrestore(&i2c->lock, flags);
 364
 365         return ret;
 366 }
 367
 368 static int meson_i2c_xfer_messages(struct i2c_adapter *adap,
 369                                    struct i2c_msg *msgs, int num, bool atomic)
 370 {
 371         struct meson_i2c *i2c = adap->algo_data;
 372         int i, ret = 0;
 373
 374         for (i = 0; i < num; i++) {
 375                 ret = meson_i2c_xfer_msg(i2c, msgs + i, i == num - 1, atomic);
 376                 if (ret)
 377                         break;
 378         }
 379
 380         return ret ?: i;
 381 }
 382
 383 static int meson_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 384                           int num)
 385 {
 386         return meson_i2c_xfer_messages(adap, msgs, num, false);
 387 }
 388
 389 static int meson_i2c_xfer_atomic(struct i2c_adapter *adap,
 390                                  struct i2c_msg *msgs, int num)
 391 {
 392         return meson_i2c_xfer_messages(adap, msgs, num, true);
 393 }
 394
 395 static u32 meson_i2c_func(struct i2c_adapter *adap)
 396 {
 397         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 398 }
 399
 400 static const struct i2c_algorithm meson_i2c_algorithm = {
 401         .master_xfer = meson_i2c_xfer,
 402         .master_xfer_atomic = meson_i2c_xfer_atomic,
 403         .functionality = meson_i2c_func,
 404 };
 405
 406 static int meson_i2c_probe(struct platform_device *pdev)
 407 {
 408         struct device_node *np = pdev->dev.of_node;
 409         struct meson_i2c *i2c;
 410         struct i2c_timings timings;
 411         int irq, ret = 0;
 412
 413         i2c = devm_kzalloc(&pdev->dev, sizeof(struct meson_i2c), GFP_KERNEL);
 414         if (!i2c)
 415                 return -ENOMEM;
 416
 417         i2c_parse_fw_timings(&pdev->dev, &timings, true);
 418
 419         i2c->dev = &pdev->dev;
 420         platform_set_drvdata(pdev, i2c);
 421
 422         spin_lock_init(&i2c->lock);
 423         init_completion(&i2c->done);
 424
 425         i2c->data = (const struct meson_i2c_data *)
 426                 of_device_get_match_data(&pdev->dev);
 427
 428         i2c->clk = devm_clk_get(&pdev->dev, NULL);
 429         if (IS_ERR(i2c->clk)) {
 430                 dev_err(&pdev->dev, "can't get device clock\n");
 431                 return PTR_ERR(i2c->clk);
 432         }
 433
 434         i2c->regs = devm_platform_ioremap_resource(pdev, 0);
 435         if (IS_ERR(i2c->regs))
 436                 return PTR_ERR(i2c->regs);
 437
 438         irq = platform_get_irq(pdev, 0);
 439         if (irq < 0)
 440                 return irq;
 441
 442         ret = devm_request_irq(&pdev->dev, irq, meson_i2c_irq, 0, NULL, i2c);
 443         if (ret < 0) {
 444                 dev_err(&pdev->dev, "can't request IRQ\n");
 445                 return ret;
 446         }
 447
 448         ret = clk_prepare_enable(i2c->clk);
 449         if (ret < 0) {
 450                 dev_err(&pdev->dev, "can't prepare clock\n");
 451                 return ret;
 452         }
 453
 454         strlcpy(i2c->adap.name, "Meson I2C adapter",
 455                 sizeof(i2c->adap.name));
 456         i2c->adap.owner = THIS_MODULE;
 457         i2c->adap.algo = &meson_i2c_algorithm;
 458         i2c->adap.dev.parent = &pdev->dev;
 459         i2c->adap.dev.of_node = np;
 460         i2c->adap.algo_data = i2c;
 461
 462         /*
 463          * A transfer is triggered when START bit changes from 0 to 1.
 464          * Ensure that the bit is set to 0 after probe
 465          */
 466         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
 467
 468         /* Disable filtering */
 469         meson_i2c_set_mask(i2c, REG_SLAVE_ADDR,
 470                            REG_SLV_SDA_FILTER | REG_SLV_SCL_FILTER, 0);
 471
 472         meson_i2c_set_clk_div(i2c, timings.bus_freq_hz);
 473
 474         ret = i2c_add_adapter(&i2c->adap);
 475         if (ret < 0) {
 476                 clk_disable_unprepare(i2c->clk);
 477                 return ret;
 478         }
 479
 480         return 0;
 481 }
 482
 483 static int meson_i2c_remove(struct platform_device *pdev)
 484 {
 485         struct meson_i2c *i2c = platform_get_drvdata(pdev);
 486
 487         i2c_del_adapter(&i2c->adap);
 488         clk_disable_unprepare(i2c->clk);
 489
 490         return 0;
 491 }
 492
 493 static const struct meson_i2c_data i2c_meson6_data = {
 494         .div_factor = 4,
 495 };
 496
 497 static const struct meson_i2c_data i2c_gxbb_data = {
 498         .div_factor = 4,
 499 };
 500
 501 static const struct meson_i2c_data i2c_axg_data = {
 502         .div_factor = 3,
 503 };
 504
 505 static const struct of_device_id meson_i2c_match[] = {
 506         { .compatible = "amlogic,meson6-i2c", .data = &i2c_meson6_data },
 507         { .compatible = "amlogic,meson-gxbb-i2c", .data = &i2c_gxbb_data },
 508         { .compatible = "amlogic,meson-axg-i2c", .data = &i2c_axg_data },
 509         {},
 510 };
 511
 512 MODULE_DEVICE_TABLE(of, meson_i2c_match);
 513
 514 static struct platform_driver meson_i2c_driver = {
 515         .probe   = meson_i2c_probe,
 516         .remove  = meson_i2c_remove,
 517         .driver  = {
 518                 .name  = "meson-i2c",
 519                 .of_match_table = meson_i2c_match,
 520         },
 521 };
 522
 523 module_platform_driver(meson_i2c_driver);
 524
 525 MODULE_DESCRIPTION("Amlogic Meson I2C Bus driver");
 526 MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
 527 MODULE_LICENSE("GPL v2");