drivers/i2c/busses/i2c-uniphier.c

   1 /*
   2  * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <linux/clk.h>
  16 #include <linux/i2c.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/io.h>
  19 #include <linux/module.h>
  20 #include <linux/platform_device.h>
  21
  22 #define UNIPHIER_I2C_DTRM       0x00    /* TX register */
  23 #define     UNIPHIER_I2C_DTRM_IRQEN     BIT(11) /* enable interrupt */
  24 #define     UNIPHIER_I2C_DTRM_STA       BIT(10) /* start condition */
  25 #define     UNIPHIER_I2C_DTRM_STO       BIT(9)  /* stop condition */
  26 #define     UNIPHIER_I2C_DTRM_NACK      BIT(8)  /* do not return ACK */
  27 #define     UNIPHIER_I2C_DTRM_RD        BIT(0)  /* read transaction */
  28 #define UNIPHIER_I2C_DREC       0x04    /* RX register */
  29 #define     UNIPHIER_I2C_DREC_MST       BIT(14) /* 1 = master, 0 = slave */
  30 #define     UNIPHIER_I2C_DREC_TX        BIT(13) /* 1 = transmit, 0 = receive */
  31 #define     UNIPHIER_I2C_DREC_STS       BIT(12) /* stop condition detected */
  32 #define     UNIPHIER_I2C_DREC_LRB       BIT(11) /* no ACK */
  33 #define     UNIPHIER_I2C_DREC_LAB       BIT(9)  /* arbitration lost */
  34 #define     UNIPHIER_I2C_DREC_BBN       BIT(8)  /* bus not busy */
  35 #define UNIPHIER_I2C_MYAD       0x08    /* slave address */
  36 #define UNIPHIER_I2C_CLK        0x0c    /* clock frequency control */
  37 #define UNIPHIER_I2C_BRST       0x10    /* bus reset */
  38 #define     UNIPHIER_I2C_BRST_FOEN      BIT(1)  /* normal operation */
  39 #define     UNIPHIER_I2C_BRST_RSCL      BIT(0)  /* release SCL */
  40 #define UNIPHIER_I2C_HOLD       0x14    /* hold time control */
  41 #define UNIPHIER_I2C_BSTS       0x18    /* bus status monitor */
  42 #define     UNIPHIER_I2C_BSTS_SDA       BIT(1)  /* readback of SDA line */
  43 #define     UNIPHIER_I2C_BSTS_SCL       BIT(0)  /* readback of SCL line */
  44 #define UNIPHIER_I2C_NOISE      0x1c    /* noise filter control */
  45 #define UNIPHIER_I2C_SETUP      0x20    /* setup time control */
  46
  47 #define UNIPHIER_I2C_DEFAULT_SPEED      100000
  48 #define UNIPHIER_I2C_MAX_SPEED          400000
  49
  50 struct uniphier_i2c_priv {
  51         struct completion comp;
  52         struct i2c_adapter adap;
  53         void __iomem *membase;
  54         struct clk *clk;
  55         unsigned int busy_cnt;
  56         unsigned int clk_cycle;
  57 };
  58
  59 static irqreturn_t uniphier_i2c_interrupt(int irq, void *dev_id)
  60 {
  61         struct uniphier_i2c_priv *priv = dev_id;
  62
  63         /*
  64          * This hardware uses edge triggered interrupt.  Do not touch the
  65          * hardware registers in this handler to make sure to catch the next
  66          * interrupt edge.  Just send a complete signal and return.
  67          */
  68         complete(&priv->comp);
  69
  70         return IRQ_HANDLED;
  71 }
  72
  73 static int uniphier_i2c_xfer_byte(struct i2c_adapter *adap, u32 txdata,
  74                                   u32 *rxdatap)
  75 {
  76         struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
  77         unsigned long time_left;
  78         u32 rxdata;
  79
  80         reinit_completion(&priv->comp);
  81
  82         txdata |= UNIPHIER_I2C_DTRM_IRQEN;
  83         dev_dbg(&adap->dev, "write data: 0x%04x\n", txdata);
  84         writel(txdata, priv->membase + UNIPHIER_I2C_DTRM);
  85
  86         time_left = wait_for_completion_timeout(&priv->comp, adap->timeout);
  87         if (unlikely(!time_left)) {
  88                 dev_err(&adap->dev, "transaction timeout\n");
  89                 return -ETIMEDOUT;
  90         }
  91
  92         rxdata = readl(priv->membase + UNIPHIER_I2C_DREC);
  93         dev_dbg(&adap->dev, "read data: 0x%04x\n", rxdata);
  94
  95         if (rxdatap)
  96                 *rxdatap = rxdata;
  97
  98         return 0;
  99 }
 100
 101 static int uniphier_i2c_send_byte(struct i2c_adapter *adap, u32 txdata)
 102 {
 103         u32 rxdata;
 104         int ret;
 105
 106         ret = uniphier_i2c_xfer_byte(adap, txdata, &rxdata);
 107         if (ret)
 108                 return ret;
 109
 110         if (unlikely(rxdata & UNIPHIER_I2C_DREC_LAB)) {
 111                 dev_dbg(&adap->dev, "arbitration lost\n");
 112                 return -EAGAIN;
 113         }
 114         if (unlikely(rxdata & UNIPHIER_I2C_DREC_LRB)) {
 115                 dev_dbg(&adap->dev, "could not get ACK\n");
 116                 return -ENXIO;
 117         }
 118
 119         return 0;
 120 }
 121
 122 static int uniphier_i2c_tx(struct i2c_adapter *adap, u16 addr, u16 len,
 123                            const u8 *buf)
 124 {
 125         int ret;
 126
 127         dev_dbg(&adap->dev, "start condition\n");
 128         ret = uniphier_i2c_send_byte(adap, addr << 1 |
 129                                      UNIPHIER_I2C_DTRM_STA |
 130                                      UNIPHIER_I2C_DTRM_NACK);
 131         if (ret)
 132                 return ret;
 133
 134         while (len--) {
 135                 ret = uniphier_i2c_send_byte(adap,
 136                                              UNIPHIER_I2C_DTRM_NACK | *buf++);
 137                 if (ret)
 138                         return ret;
 139         }
 140
 141         return 0;
 142 }
 143
 144 static int uniphier_i2c_rx(struct i2c_adapter *adap, u16 addr, u16 len,
 145                            u8 *buf)
 146 {
 147         int ret;
 148
 149         dev_dbg(&adap->dev, "start condition\n");
 150         ret = uniphier_i2c_send_byte(adap, addr << 1 |
 151                                      UNIPHIER_I2C_DTRM_STA |
 152                                      UNIPHIER_I2C_DTRM_NACK |
 153                                      UNIPHIER_I2C_DTRM_RD);
 154         if (ret)
 155                 return ret;
 156
 157         while (len--) {
 158                 u32 rxdata;
 159
 160                 ret = uniphier_i2c_xfer_byte(adap,
 161                                              len ? 0 : UNIPHIER_I2C_DTRM_NACK,
 162                                              &rxdata);
 163                 if (ret)
 164                         return ret;
 165                 *buf++ = rxdata;
 166         }
 167
 168         return 0;
 169 }
 170
 171 static int uniphier_i2c_stop(struct i2c_adapter *adap)
 172 {
 173         dev_dbg(&adap->dev, "stop condition\n");
 174         return uniphier_i2c_send_byte(adap, UNIPHIER_I2C_DTRM_STO |
 175                                       UNIPHIER_I2C_DTRM_NACK);
 176 }
 177
 178 static int uniphier_i2c_master_xfer_one(struct i2c_adapter *adap,
 179                                         struct i2c_msg *msg, bool stop)
 180 {
 181         bool is_read = msg->flags & I2C_M_RD;
 182         bool recovery = false;
 183         int ret;
 184
 185         dev_dbg(&adap->dev, "%s: addr=0x%02x, len=%d, stop=%d\n",
 186                 is_read ? "receive" : "transmit", msg->addr, msg->len, stop);
 187
 188         if (is_read)
 189                 ret = uniphier_i2c_rx(adap, msg->addr, msg->len, msg->buf);
 190         else
 191                 ret = uniphier_i2c_tx(adap, msg->addr, msg->len, msg->buf);
 192
 193         if (ret == -EAGAIN) /* could not acquire bus. bail out without STOP */
 194                 return ret;
 195
 196         if (ret == -ETIMEDOUT) {
 197                 /* This error is fatal.  Needs recovery. */
 198                 stop = false;
 199                 recovery = true;
 200         }
 201
 202         if (stop) {
 203                 int ret2 = uniphier_i2c_stop(adap);
 204
 205                 if (ret2) {
 206                         /* Failed to issue STOP.  The bus needs recovery. */
 207                         recovery = true;
 208                         ret = ret ?: ret2;
 209                 }
 210         }
 211
 212         if (recovery)
 213                 i2c_recover_bus(adap);
 214
 215         return ret;
 216 }
 217
 218 static int uniphier_i2c_check_bus_busy(struct i2c_adapter *adap)
 219 {
 220         struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
 221
 222         if (!(readl(priv->membase + UNIPHIER_I2C_DREC) &
 223                                                 UNIPHIER_I2C_DREC_BBN)) {
 224                 if (priv->busy_cnt++ > 3) {
 225                         /*
 226                          * If bus busy continues too long, it is probably
 227                          * in a wrong state.  Try bus recovery.
 228                          */
 229                         i2c_recover_bus(adap);
 230                         priv->busy_cnt = 0;
 231                 }
 232
 233                 return -EAGAIN;
 234         }
 235
 236         priv->busy_cnt = 0;
 237         return 0;
 238 }
 239
 240 static int uniphier_i2c_master_xfer(struct i2c_adapter *adap,
 241                                     struct i2c_msg *msgs, int num)
 242 {
 243         struct i2c_msg *msg, *emsg = msgs + num;
 244         int ret;
 245
 246         ret = uniphier_i2c_check_bus_busy(adap);
 247         if (ret)
 248                 return ret;
 249
 250         for (msg = msgs; msg < emsg; msg++) {
 251                 /* If next message is read, skip the stop condition */
 252                 bool stop = !(msg + 1 < emsg && msg[1].flags & I2C_M_RD);
 253                 /* but, force it if I2C_M_STOP is set */
 254                 if (msg->flags & I2C_M_STOP)
 255                         stop = true;
 256
 257                 ret = uniphier_i2c_master_xfer_one(adap, msg, stop);
 258                 if (ret)
 259                         return ret;
 260         }
 261
 262         return num;
 263 }
 264
 265 static u32 uniphier_i2c_functionality(struct i2c_adapter *adap)
 266 {
 267         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 268 }
 269
 270 static const struct i2c_algorithm uniphier_i2c_algo = {
 271         .master_xfer = uniphier_i2c_master_xfer,
 272         .functionality = uniphier_i2c_functionality,
 273 };
 274
 275 static void uniphier_i2c_reset(struct uniphier_i2c_priv *priv, bool reset_on)
 276 {
 277         u32 val = UNIPHIER_I2C_BRST_RSCL;
 278
 279         val |= reset_on ? 0 : UNIPHIER_I2C_BRST_FOEN;
 280         writel(val, priv->membase + UNIPHIER_I2C_BRST);
 281 }
 282
 283 static int uniphier_i2c_get_scl(struct i2c_adapter *adap)
 284 {
 285         struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
 286
 287         return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) &
 288                                                         UNIPHIER_I2C_BSTS_SCL);
 289 }
 290
 291 static void uniphier_i2c_set_scl(struct i2c_adapter *adap, int val)
 292 {
 293         struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
 294
 295         writel(val ? UNIPHIER_I2C_BRST_RSCL : 0,
 296                priv->membase + UNIPHIER_I2C_BRST);
 297 }
 298
 299 static int uniphier_i2c_get_sda(struct i2c_adapter *adap)
 300 {
 301         struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
 302
 303         return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) &
 304                                                         UNIPHIER_I2C_BSTS_SDA);
 305 }
 306
 307 static void uniphier_i2c_unprepare_recovery(struct i2c_adapter *adap)
 308 {
 309         uniphier_i2c_reset(i2c_get_adapdata(adap), false);
 310 }
 311
 312 static struct i2c_bus_recovery_info uniphier_i2c_bus_recovery_info = {
 313         .recover_bus = i2c_generic_scl_recovery,
 314         .get_scl = uniphier_i2c_get_scl,
 315         .set_scl = uniphier_i2c_set_scl,
 316         .get_sda = uniphier_i2c_get_sda,
 317         .unprepare_recovery = uniphier_i2c_unprepare_recovery,
 318 };
 319
 320 static void uniphier_i2c_hw_init(struct uniphier_i2c_priv *priv)
 321 {
 322         unsigned int cyc = priv->clk_cycle;
 323
 324         uniphier_i2c_reset(priv, true);
 325
 326         writel((cyc / 2 << 16) | cyc, priv->membase + UNIPHIER_I2C_CLK);
 327
 328         uniphier_i2c_reset(priv, false);
 329 }
 330
 331 static int uniphier_i2c_probe(struct platform_device *pdev)
 332 {
 333         struct device *dev = &pdev->dev;
 334         struct uniphier_i2c_priv *priv;
 335         struct resource *regs;
 336         u32 bus_speed;
 337         unsigned long clk_rate;
 338         int irq, ret;
 339
 340         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 341         if (!priv)
 342                 return -ENOMEM;
 343
 344         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 345         priv->membase = devm_ioremap_resource(dev, regs);
 346         if (IS_ERR(priv->membase))
 347                 return PTR_ERR(priv->membase);
 348
 349         irq = platform_get_irq(pdev, 0);
 350         if (irq < 0) {
 351                 dev_err(dev, "failed to get IRQ number\n");
 352                 return irq;
 353         }
 354
 355         if (of_property_read_u32(dev->of_node, "clock-frequency", &bus_speed))
 356                 bus_speed = UNIPHIER_I2C_DEFAULT_SPEED;
 357
 358         if (!bus_speed || bus_speed > UNIPHIER_I2C_MAX_SPEED) {
 359                 dev_err(dev, "invalid clock-frequency %d\n", bus_speed);
 360                 return -EINVAL;
 361         }
 362
 363         priv->clk = devm_clk_get(dev, NULL);
 364         if (IS_ERR(priv->clk)) {
 365                 dev_err(dev, "failed to get clock\n");
 366                 return PTR_ERR(priv->clk);
 367         }
 368
 369         ret = clk_prepare_enable(priv->clk);
 370         if (ret)
 371                 return ret;
 372
 373         clk_rate = clk_get_rate(priv->clk);
 374         if (!clk_rate) {
 375                 dev_err(dev, "input clock rate should not be zero\n");
 376                 ret = -EINVAL;
 377                 goto disable_clk;
 378         }
 379
 380         priv->clk_cycle = clk_rate / bus_speed;
 381         init_completion(&priv->comp);
 382         priv->adap.owner = THIS_MODULE;
 383         priv->adap.algo = &uniphier_i2c_algo;
 384         priv->adap.dev.parent = dev;
 385         priv->adap.dev.of_node = dev->of_node;
 386         strlcpy(priv->adap.name, "UniPhier I2C", sizeof(priv->adap.name));
 387         priv->adap.bus_recovery_info = &uniphier_i2c_bus_recovery_info;
 388         i2c_set_adapdata(&priv->adap, priv);
 389         platform_set_drvdata(pdev, priv);
 390
 391         uniphier_i2c_hw_init(priv);
 392
 393         ret = devm_request_irq(dev, irq, uniphier_i2c_interrupt, 0, pdev->name,
 394                                priv);
 395         if (ret) {
 396                 dev_err(dev, "failed to request irq %d\n", irq);
 397                 goto disable_clk;
 398         }
 399
 400         ret = i2c_add_adapter(&priv->adap);
 401 disable_clk:
 402         if (ret)
 403                 clk_disable_unprepare(priv->clk);
 404
 405         return ret;
 406 }
 407
 408 static int uniphier_i2c_remove(struct platform_device *pdev)
 409 {
 410         struct uniphier_i2c_priv *priv = platform_get_drvdata(pdev);
 411
 412         i2c_del_adapter(&priv->adap);
 413         clk_disable_unprepare(priv->clk);
 414
 415         return 0;
 416 }
 417
 418 static int __maybe_unused uniphier_i2c_suspend(struct device *dev)
 419 {
 420         struct uniphier_i2c_priv *priv = dev_get_drvdata(dev);
 421
 422         clk_disable_unprepare(priv->clk);
 423
 424         return 0;
 425 }
 426
 427 static int __maybe_unused uniphier_i2c_resume(struct device *dev)
 428 {
 429         struct uniphier_i2c_priv *priv = dev_get_drvdata(dev);
 430         int ret;
 431
 432         ret = clk_prepare_enable(priv->clk);
 433         if (ret)
 434                 return ret;
 435
 436         uniphier_i2c_hw_init(priv);
 437
 438         return 0;
 439 }
 440
 441 static const struct dev_pm_ops uniphier_i2c_pm_ops = {
 442         SET_SYSTEM_SLEEP_PM_OPS(uniphier_i2c_suspend, uniphier_i2c_resume)
 443 };
 444
 445 static const struct of_device_id uniphier_i2c_match[] = {
 446         { .compatible = "socionext,uniphier-i2c" },
 447         { /* sentinel */ }
 448 };
 449 MODULE_DEVICE_TABLE(of, uniphier_i2c_match);
 450
 451 static struct platform_driver uniphier_i2c_drv = {
 452         .probe  = uniphier_i2c_probe,
 453         .remove = uniphier_i2c_remove,
 454         .driver = {
 455                 .name  = "uniphier-i2c",
 456                 .of_match_table = uniphier_i2c_match,
 457                 .pm = &uniphier_i2c_pm_ops,
 458         },
 459 };
 460 module_platform_driver(uniphier_i2c_drv);
 461
 462 MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
 463 MODULE_DESCRIPTION("UniPhier I2C bus driver");
 464 MODULE_LICENSE("GPL");