drivers/i2c/busses/i2c-meson.c

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