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/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_SHIFT   12
  38 #define REG_CTRL_CLKDIV_MASK    GENMASK(21, 12)
  39 #define REG_CTRL_CLKDIVEXT_SHIFT 28
  40 #define REG_CTRL_CLKDIVEXT_MASK GENMASK(29, 28)
  41
  42 #define I2C_TIMEOUT_MS          500
  43
  44 enum {
  45         TOKEN_END = 0,
  46         TOKEN_START,
  47         TOKEN_SLAVE_ADDR_WRITE,
  48         TOKEN_SLAVE_ADDR_READ,
  49         TOKEN_DATA,
  50         TOKEN_DATA_LAST,
  51         TOKEN_STOP,
  52 };
  53
  54 enum {
  55         STATE_IDLE,
  56         STATE_READ,
  57         STATE_WRITE,
  58 };
  59
  60 /**
  61  * struct meson_i2c - Meson I2C device private data
  62  *
  63  * @adap:       I2C adapter instance
  64  * @dev:        Pointer to device structure
  65  * @regs:       Base address of the device memory mapped registers
  66  * @clk:        Pointer to clock structure
  67  * @irq:        IRQ number
  68  * @msg:        Pointer to the current I2C message
  69  * @state:      Current state in the driver state machine
  70  * @last:       Flag set for the last message in the transfer
  71  * @count:      Number of bytes to be sent/received in current transfer
  72  * @pos:        Current position in the send/receive buffer
  73  * @error:      Flag set when an error is received
  74  * @lock:       To avoid race conditions between irq handler and xfer code
  75  * @done:       Completion used to wait for transfer termination
  76  * @tokens:     Sequence of tokens to be written to the device
  77  * @num_tokens: Number of tokens
  78  */
  79 struct meson_i2c {
  80         struct i2c_adapter      adap;
  81         struct device           *dev;
  82         void __iomem            *regs;
  83         struct clk              *clk;
  84
  85         struct i2c_msg          *msg;
  86         int                     state;
  87         bool                    last;
  88         int                     count;
  89         int                     pos;
  90         int                     error;
  91
  92         spinlock_t              lock;
  93         struct completion       done;
  94         u32                     tokens[2];
  95         int                     num_tokens;
  96 };
  97
  98 static void meson_i2c_set_mask(struct meson_i2c *i2c, int reg, u32 mask,
  99                                u32 val)
 100 {
 101         u32 data;
 102
 103         data = readl(i2c->regs + reg);
 104         data &= ~mask;
 105         data |= val & mask;
 106         writel(data, i2c->regs + reg);
 107 }
 108
 109 static void meson_i2c_reset_tokens(struct meson_i2c *i2c)
 110 {
 111         i2c->tokens[0] = 0;
 112         i2c->tokens[1] = 0;
 113         i2c->num_tokens = 0;
 114 }
 115
 116 static void meson_i2c_add_token(struct meson_i2c *i2c, int token)
 117 {
 118         if (i2c->num_tokens < 8)
 119                 i2c->tokens[0] |= (token & 0xf) << (i2c->num_tokens * 4);
 120         else
 121                 i2c->tokens[1] |= (token & 0xf) << ((i2c->num_tokens % 8) * 4);
 122
 123         i2c->num_tokens++;
 124 }
 125
 126 static void meson_i2c_write_tokens(struct meson_i2c *i2c)
 127 {
 128         writel(i2c->tokens[0], i2c->regs + REG_TOK_LIST0);
 129         writel(i2c->tokens[1], i2c->regs + REG_TOK_LIST1);
 130 }
 131
 132 static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq)
 133 {
 134         unsigned long clk_rate = clk_get_rate(i2c->clk);
 135         unsigned int div;
 136
 137         div = DIV_ROUND_UP(clk_rate, freq * 4);
 138
 139         /* clock divider has 12 bits */
 140         if (div >= (1 << 12)) {
 141                 dev_err(i2c->dev, "requested bus frequency too low\n");
 142                 div = (1 << 12) - 1;
 143         }
 144
 145         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK,
 146                            (div & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);
 147
 148         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT_MASK,
 149                            (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
 150
 151         dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
 152                 clk_rate, freq, div);
 153 }
 154
 155 static void meson_i2c_get_data(struct meson_i2c *i2c, char *buf, int len)
 156 {
 157         u32 rdata0, rdata1;
 158         int i;
 159
 160         rdata0 = readl(i2c->regs + REG_TOK_RDATA0);
 161         rdata1 = readl(i2c->regs + REG_TOK_RDATA1);
 162
 163         dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
 164                 rdata0, rdata1, len);
 165
 166         for (i = 0; i < min(4, len); i++)
 167                 *buf++ = (rdata0 >> i * 8) & 0xff;
 168
 169         for (i = 4; i < min(8, len); i++)
 170                 *buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
 171 }
 172
 173 static void meson_i2c_put_data(struct meson_i2c *i2c, char *buf, int len)
 174 {
 175         u32 wdata0 = 0, wdata1 = 0;
 176         int i;
 177
 178         for (i = 0; i < min(4, len); i++)
 179                 wdata0 |= *buf++ << (i * 8);
 180
 181         for (i = 4; i < min(8, len); i++)
 182                 wdata1 |= *buf++ << ((i - 4) * 8);
 183
 184         writel(wdata0, i2c->regs + REG_TOK_WDATA0);
 185         writel(wdata1, i2c->regs + REG_TOK_WDATA1);
 186
 187         dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
 188                 wdata0, wdata1, len);
 189 }
 190
 191 static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
 192 {
 193         bool write = !(i2c->msg->flags & I2C_M_RD);
 194         int i;
 195
 196         i2c->count = min(i2c->msg->len - i2c->pos, 8);
 197
 198         for (i = 0; i < i2c->count - 1; i++)
 199                 meson_i2c_add_token(i2c, TOKEN_DATA);
 200
 201         if (i2c->count) {
 202                 if (write || i2c->pos + i2c->count < i2c->msg->len)
 203                         meson_i2c_add_token(i2c, TOKEN_DATA);
 204                 else
 205                         meson_i2c_add_token(i2c, TOKEN_DATA_LAST);
 206         }
 207
 208         if (write)
 209                 meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);
 210
 211         if (i2c->last && i2c->pos + i2c->count >= i2c->msg->len)
 212                 meson_i2c_add_token(i2c, TOKEN_STOP);
 213 }
 214
 215 static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
 216 {
 217         struct meson_i2c *i2c = dev_id;
 218         unsigned int ctrl;
 219
 220         spin_lock(&i2c->lock);
 221
 222         meson_i2c_reset_tokens(i2c);
 223         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
 224         ctrl = readl(i2c->regs + REG_CTRL);
 225
 226         dev_dbg(i2c->dev, "irq: state %d, pos %d, count %d, ctrl %08x\n",
 227                 i2c->state, i2c->pos, i2c->count, ctrl);
 228
 229         if (i2c->state == STATE_IDLE) {
 230                 spin_unlock(&i2c->lock);
 231                 return IRQ_NONE;
 232         }
 233
 234         if (ctrl & REG_CTRL_ERROR) {
 235                 /*
 236                  * The bit is set when the IGNORE_NAK bit is cleared
 237                  * and the device didn't respond. In this case, the
 238                  * I2C controller automatically generates a STOP
 239                  * condition.
 240                  */
 241                 dev_dbg(i2c->dev, "error bit set\n");
 242                 i2c->error = -ENXIO;
 243                 i2c->state = STATE_IDLE;
 244                 complete(&i2c->done);
 245                 goto out;
 246         }
 247
 248         switch (i2c->state) {
 249         case STATE_READ:
 250                 if (i2c->count > 0) {
 251                         meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos,
 252                                            i2c->count);
 253                         i2c->pos += i2c->count;
 254                 }
 255
 256                 if (i2c->pos >= i2c->msg->len) {
 257                         i2c->state = STATE_IDLE;
 258                         complete(&i2c->done);
 259                         break;
 260                 }
 261
 262                 meson_i2c_prepare_xfer(i2c);
 263                 break;
 264         case STATE_WRITE:
 265                 i2c->pos += i2c->count;
 266
 267                 if (i2c->pos >= i2c->msg->len) {
 268                         i2c->state = STATE_IDLE;
 269                         complete(&i2c->done);
 270                         break;
 271                 }
 272
 273                 meson_i2c_prepare_xfer(i2c);
 274                 break;
 275         }
 276
 277 out:
 278         if (i2c->state != STATE_IDLE) {
 279                 /* Restart the processing */
 280                 meson_i2c_write_tokens(i2c);
 281                 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START,
 282                                    REG_CTRL_START);
 283         }
 284
 285         spin_unlock(&i2c->lock);
 286
 287         return IRQ_HANDLED;
 288 }
 289
 290 static void meson_i2c_do_start(struct meson_i2c *i2c, struct i2c_msg *msg)
 291 {
 292         int token;
 293
 294         token = (msg->flags & I2C_M_RD) ? TOKEN_SLAVE_ADDR_READ :
 295                 TOKEN_SLAVE_ADDR_WRITE;
 296
 297         writel(msg->addr << 1, i2c->regs + REG_SLAVE_ADDR);
 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)
 304 {
 305         unsigned long time_left, flags;
 306         int ret = 0;
 307
 308         i2c->msg = msg;
 309         i2c->last = last;
 310         i2c->pos = 0;
 311         i2c->count = 0;
 312         i2c->error = 0;
 313
 314         meson_i2c_reset_tokens(i2c);
 315
 316         flags = (msg->flags & I2C_M_IGNORE_NAK) ? REG_CTRL_ACK_IGNORE : 0;
 317         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_ACK_IGNORE, flags);
 318
 319         if (!(msg->flags & I2C_M_NOSTART))
 320                 meson_i2c_do_start(i2c, msg);
 321
 322         i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
 323         meson_i2c_prepare_xfer(i2c);
 324         meson_i2c_write_tokens(i2c);
 325         reinit_completion(&i2c->done);
 326
 327         /* Start the transfer */
 328         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, REG_CTRL_START);
 329
 330         time_left = msecs_to_jiffies(I2C_TIMEOUT_MS);
 331         time_left = wait_for_completion_timeout(&i2c->done, time_left);
 332
 333         /*
 334          * Protect access to i2c struct and registers from interrupt
 335          * handlers triggered by a transfer terminated after the
 336          * timeout period
 337          */
 338         spin_lock_irqsave(&i2c->lock, flags);
 339
 340         /* Abort any active operation */
 341         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
 342
 343         if (!time_left) {
 344                 i2c->state = STATE_IDLE;
 345                 ret = -ETIMEDOUT;
 346         }
 347
 348         if (i2c->error)
 349                 ret = i2c->error;
 350
 351         spin_unlock_irqrestore(&i2c->lock, flags);
 352
 353         return ret;
 354 }
 355
 356 static int meson_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 357                           int num)
 358 {
 359         struct meson_i2c *i2c = adap->algo_data;
 360         int i, ret = 0;
 361
 362         clk_enable(i2c->clk);
 363
 364         for (i = 0; i < num; i++) {
 365                 ret = meson_i2c_xfer_msg(i2c, msgs + i, i == num - 1);
 366                 if (ret)
 367                         break;
 368         }
 369
 370         clk_disable(i2c->clk);
 371
 372         return ret ?: i;
 373 }
 374
 375 static u32 meson_i2c_func(struct i2c_adapter *adap)
 376 {
 377         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 378 }
 379
 380 static const struct i2c_algorithm meson_i2c_algorithm = {
 381         .master_xfer    = meson_i2c_xfer,
 382         .functionality  = meson_i2c_func,
 383 };
 384
 385 static int meson_i2c_probe(struct platform_device *pdev)
 386 {
 387         struct device_node *np = pdev->dev.of_node;
 388         struct meson_i2c *i2c;
 389         struct resource *mem;
 390         struct i2c_timings timings;
 391         int irq, ret = 0;
 392
 393         i2c = devm_kzalloc(&pdev->dev, sizeof(struct meson_i2c), GFP_KERNEL);
 394         if (!i2c)
 395                 return -ENOMEM;
 396
 397         i2c_parse_fw_timings(&pdev->dev, &timings, true);
 398
 399         i2c->dev = &pdev->dev;
 400         platform_set_drvdata(pdev, i2c);
 401
 402         spin_lock_init(&i2c->lock);
 403         init_completion(&i2c->done);
 404
 405         i2c->clk = devm_clk_get(&pdev->dev, NULL);
 406         if (IS_ERR(i2c->clk)) {
 407                 dev_err(&pdev->dev, "can't get device clock\n");
 408                 return PTR_ERR(i2c->clk);
 409         }
 410
 411         mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 412         i2c->regs = devm_ioremap_resource(&pdev->dev, mem);
 413         if (IS_ERR(i2c->regs))
 414                 return PTR_ERR(i2c->regs);
 415
 416         irq = platform_get_irq(pdev, 0);
 417         if (irq < 0) {
 418                 dev_err(&pdev->dev, "can't find IRQ\n");
 419                 return irq;
 420         }
 421
 422         ret = devm_request_irq(&pdev->dev, irq, meson_i2c_irq, 0, NULL, i2c);
 423         if (ret < 0) {
 424                 dev_err(&pdev->dev, "can't request IRQ\n");
 425                 return ret;
 426         }
 427
 428         ret = clk_prepare(i2c->clk);
 429         if (ret < 0) {
 430                 dev_err(&pdev->dev, "can't prepare clock\n");
 431                 return ret;
 432         }
 433
 434         strlcpy(i2c->adap.name, "Meson I2C adapter",
 435                 sizeof(i2c->adap.name));
 436         i2c->adap.owner = THIS_MODULE;
 437         i2c->adap.algo = &meson_i2c_algorithm;
 438         i2c->adap.dev.parent = &pdev->dev;
 439         i2c->adap.dev.of_node = np;
 440         i2c->adap.algo_data = i2c;
 441
 442         /*
 443          * A transfer is triggered when START bit changes from 0 to 1.
 444          * Ensure that the bit is set to 0 after probe
 445          */
 446         meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
 447
 448         ret = i2c_add_adapter(&i2c->adap);
 449         if (ret < 0) {
 450                 clk_unprepare(i2c->clk);
 451                 return ret;
 452         }
 453
 454         meson_i2c_set_clk_div(i2c, timings.bus_freq_hz);
 455
 456         return 0;
 457 }
 458
 459 static int meson_i2c_remove(struct platform_device *pdev)
 460 {
 461         struct meson_i2c *i2c = platform_get_drvdata(pdev);
 462
 463         i2c_del_adapter(&i2c->adap);
 464         clk_unprepare(i2c->clk);
 465
 466         return 0;
 467 }
 468
 469 static const struct of_device_id meson_i2c_match[] = {
 470         { .compatible = "amlogic,meson6-i2c" },
 471         { .compatible = "amlogic,meson-gxbb-i2c" },
 472         { },
 473 };
 474 MODULE_DEVICE_TABLE(of, meson_i2c_match);
 475
 476 static struct platform_driver meson_i2c_driver = {
 477         .probe   = meson_i2c_probe,
 478         .remove  = meson_i2c_remove,
 479         .driver  = {
 480                 .name  = "meson-i2c",
 481                 .of_match_table = meson_i2c_match,
 482         },
 483 };
 484
 485 module_platform_driver(meson_i2c_driver);
 486
 487 MODULE_DESCRIPTION("Amlogic Meson I2C Bus driver");
 488 MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
 489 MODULE_LICENSE("GPL v2");