root/drivers/i2c/busses/i2c-emev2.c

DEFINITIONS

1. em_clear_set_bit
2. em_i2c_wait_for_event
3. em_i2c_stop
4. em_i2c_reset
5. __em_i2c_xfer
6. em_i2c_xfer
7. em_i2c_slave_irq
8. em_i2c_irq_handler
9. em_i2c_func
10. em_i2c_reg_slave
11. em_i2c_unreg_slave
12. em_i2c_probe
13. em_i2c_remove

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * I2C driver for the Renesas EMEV2 SoC
   4  *
   5  * Copyright (C) 2015 Wolfram Sang <wsa@sang-engineering.com>
   6  * Copyright 2013 Codethink Ltd.
   7  * Copyright 2010-2015 Renesas Electronics Corporation
   8  */
   9 
  10 #include <linux/clk.h>
  11 #include <linux/completion.h>
  12 #include <linux/device.h>
  13 #include <linux/i2c.h>
  14 #include <linux/init.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/io.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/of_device.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/sched.h>
  22 
  23 /* I2C Registers */
  24 #define I2C_OFS_IICACT0         0x00    /* start */
  25 #define I2C_OFS_IIC0            0x04    /* shift */
  26 #define I2C_OFS_IICC0           0x08    /* control */
  27 #define I2C_OFS_SVA0            0x0c    /* slave address */
  28 #define I2C_OFS_IICCL0          0x10    /* clock select */
  29 #define I2C_OFS_IICX0           0x14    /* extension */
  30 #define I2C_OFS_IICS0           0x18    /* status */
  31 #define I2C_OFS_IICSE0          0x1c    /* status For emulation */
  32 #define I2C_OFS_IICF0           0x20    /* IIC flag */
  33 
  34 /* I2C IICACT0 Masks */
  35 #define I2C_BIT_IICE0           0x0001
  36 
  37 /* I2C IICC0 Masks */
  38 #define I2C_BIT_LREL0           0x0040
  39 #define I2C_BIT_WREL0           0x0020
  40 #define I2C_BIT_SPIE0           0x0010
  41 #define I2C_BIT_WTIM0           0x0008
  42 #define I2C_BIT_ACKE0           0x0004
  43 #define I2C_BIT_STT0            0x0002
  44 #define I2C_BIT_SPT0            0x0001
  45 
  46 /* I2C IICCL0 Masks */
  47 #define I2C_BIT_SMC0            0x0008
  48 #define I2C_BIT_DFC0            0x0004
  49 
  50 /* I2C IICSE0 Masks */
  51 #define I2C_BIT_MSTS0           0x0080
  52 #define I2C_BIT_ALD0            0x0040
  53 #define I2C_BIT_EXC0            0x0020
  54 #define I2C_BIT_COI0            0x0010
  55 #define I2C_BIT_TRC0            0x0008
  56 #define I2C_BIT_ACKD0           0x0004
  57 #define I2C_BIT_STD0            0x0002
  58 #define I2C_BIT_SPD0            0x0001
  59 
  60 /* I2C IICF0 Masks */
  61 #define I2C_BIT_STCF            0x0080
  62 #define I2C_BIT_IICBSY          0x0040
  63 #define I2C_BIT_STCEN           0x0002
  64 #define I2C_BIT_IICRSV          0x0001
  65 
  66 struct em_i2c_device {
  67         void __iomem *base;
  68         struct i2c_adapter adap;
  69         struct completion msg_done;
  70         struct clk *sclk;
  71         struct i2c_client *slave;
  72         int irq;
  73 };
  74 
  75 static inline void em_clear_set_bit(struct em_i2c_device *priv, u8 clear, u8 set, u8 reg)
  76 {
  77         writeb((readb(priv->base + reg) & ~clear) | set, priv->base + reg);
  78 }
  79 
  80 static int em_i2c_wait_for_event(struct em_i2c_device *priv)
  81 {
  82         unsigned long time_left;
  83         int status;
  84 
  85         reinit_completion(&priv->msg_done);
  86 
  87         time_left = wait_for_completion_timeout(&priv->msg_done, priv->adap.timeout);
  88 
  89         if (!time_left)
  90                 return -ETIMEDOUT;
  91 
  92         status = readb(priv->base + I2C_OFS_IICSE0);
  93         return status & I2C_BIT_ALD0 ? -EAGAIN : status;
  94 }
  95 
  96 static void em_i2c_stop(struct em_i2c_device *priv)
  97 {
  98         /* Send Stop condition */
  99         em_clear_set_bit(priv, 0, I2C_BIT_SPT0 | I2C_BIT_SPIE0, I2C_OFS_IICC0);
 100 
 101         /* Wait for stop condition */
 102         em_i2c_wait_for_event(priv);
 103 }
 104 
 105 static void em_i2c_reset(struct i2c_adapter *adap)
 106 {
 107         struct em_i2c_device *priv = i2c_get_adapdata(adap);
 108         int retr;
 109 
 110         /* If I2C active */
 111         if (readb(priv->base + I2C_OFS_IICACT0) & I2C_BIT_IICE0) {
 112                 /* Disable I2C operation */
 113                 writeb(0, priv->base + I2C_OFS_IICACT0);
 114 
 115                 retr = 1000;
 116                 while (readb(priv->base + I2C_OFS_IICACT0) == 1 && retr)
 117                         retr--;
 118                 WARN_ON(retr == 0);
 119         }
 120 
 121         /* Transfer mode set */
 122         writeb(I2C_BIT_DFC0, priv->base + I2C_OFS_IICCL0);
 123 
 124         /* Can Issue start without detecting a stop, Reservation disabled. */
 125         writeb(I2C_BIT_STCEN | I2C_BIT_IICRSV, priv->base + I2C_OFS_IICF0);
 126 
 127         /* I2C enable, 9 bit interrupt mode */
 128         writeb(I2C_BIT_WTIM0, priv->base + I2C_OFS_IICC0);
 129 
 130         /* Enable I2C operation */
 131         writeb(I2C_BIT_IICE0, priv->base + I2C_OFS_IICACT0);
 132 
 133         retr = 1000;
 134         while (readb(priv->base + I2C_OFS_IICACT0) == 0 && retr)
 135                 retr--;
 136         WARN_ON(retr == 0);
 137 }
 138 
 139 static int __em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msg,
 140                                 int stop)
 141 {
 142         struct em_i2c_device *priv = i2c_get_adapdata(adap);
 143         int count, status, read = !!(msg->flags & I2C_M_RD);
 144 
 145         /* Send start condition */
 146         em_clear_set_bit(priv, 0, I2C_BIT_ACKE0 | I2C_BIT_WTIM0, I2C_OFS_IICC0);
 147         em_clear_set_bit(priv, 0, I2C_BIT_STT0, I2C_OFS_IICC0);
 148 
 149         /* Send slave address and R/W type */
 150         writeb(i2c_8bit_addr_from_msg(msg), priv->base + I2C_OFS_IIC0);
 151 
 152         /* Wait for transaction */
 153         status = em_i2c_wait_for_event(priv);
 154         if (status < 0)
 155                 goto out_reset;
 156 
 157         /* Received NACK (result of setting slave address and R/W) */
 158         if (!(status & I2C_BIT_ACKD0)) {
 159                 em_i2c_stop(priv);
 160                 goto out;
 161         }
 162 
 163         /* Extra setup for read transactions */
 164         if (read) {
 165                 /* 8 bit interrupt mode */
 166                 em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_ACKE0, I2C_OFS_IICC0);
 167                 em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_WREL0, I2C_OFS_IICC0);
 168 
 169                 /* Wait for transaction */
 170                 status = em_i2c_wait_for_event(priv);
 171                 if (status < 0)
 172                         goto out_reset;
 173         }
 174 
 175         /* Send / receive data */
 176         for (count = 0; count < msg->len; count++) {
 177                 if (read) { /* Read transaction */
 178                         msg->buf[count] = readb(priv->base + I2C_OFS_IIC0);
 179                         em_clear_set_bit(priv, 0, I2C_BIT_WREL0, I2C_OFS_IICC0);
 180 
 181                 } else { /* Write transaction */
 182                         /* Received NACK */
 183                         if (!(status & I2C_BIT_ACKD0)) {
 184                                 em_i2c_stop(priv);
 185                                 goto out;
 186                         }
 187 
 188                         /* Write data */
 189                         writeb(msg->buf[count], priv->base + I2C_OFS_IIC0);
 190                 }
 191 
 192                 /* Wait for R/W transaction */
 193                 status = em_i2c_wait_for_event(priv);
 194                 if (status < 0)
 195                         goto out_reset;
 196         }
 197 
 198         if (stop)
 199                 em_i2c_stop(priv);
 200 
 201         return count;
 202 
 203 out_reset:
 204         em_i2c_reset(adap);
 205 out:
 206         return status < 0 ? status : -ENXIO;
 207 }
 208 
 209 static int em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 210         int num)
 211 {
 212         struct em_i2c_device *priv = i2c_get_adapdata(adap);
 213         int ret, i;
 214 
 215         if (readb(priv->base + I2C_OFS_IICF0) & I2C_BIT_IICBSY)
 216                 return -EAGAIN;
 217 
 218         for (i = 0; i < num; i++) {
 219                 ret = __em_i2c_xfer(adap, &msgs[i], (i == (num - 1)));
 220                 if (ret < 0)
 221                         return ret;
 222         }
 223 
 224         /* I2C transfer completed */
 225         return num;
 226 }
 227 
 228 static bool em_i2c_slave_irq(struct em_i2c_device *priv)
 229 {
 230         u8 status, value;
 231         enum i2c_slave_event event;
 232         int ret;
 233 
 234         if (!priv->slave)
 235                 return false;
 236 
 237         status = readb(priv->base + I2C_OFS_IICSE0);
 238 
 239         /* Extension code, do not participate */
 240         if (status & I2C_BIT_EXC0) {
 241                 em_clear_set_bit(priv, 0, I2C_BIT_LREL0, I2C_OFS_IICC0);
 242                 return true;
 243         }
 244 
 245         /* Stop detected, we don't know if it's for slave or master */
 246         if (status & I2C_BIT_SPD0) {
 247                 /* Notify slave device */
 248                 i2c_slave_event(priv->slave, I2C_SLAVE_STOP, &value);
 249                 /* Pretend we did not handle the interrupt */
 250                 return false;
 251         }
 252 
 253         /* Only handle interrupts addressed to us */
 254         if (!(status & I2C_BIT_COI0))
 255                 return false;
 256 
 257         /* Enable stop interrupts */
 258         em_clear_set_bit(priv, 0, I2C_BIT_SPIE0, I2C_OFS_IICC0);
 259 
 260         /* Transmission or Reception */
 261         if (status & I2C_BIT_TRC0) {
 262                 if (status & I2C_BIT_ACKD0) {
 263                         /* 9 bit interrupt mode */
 264                         em_clear_set_bit(priv, 0, I2C_BIT_WTIM0, I2C_OFS_IICC0);
 265 
 266                         /* Send data */
 267                         event = status & I2C_BIT_STD0 ?
 268                                 I2C_SLAVE_READ_REQUESTED :
 269                                 I2C_SLAVE_READ_PROCESSED;
 270                         i2c_slave_event(priv->slave, event, &value);
 271                         writeb(value, priv->base + I2C_OFS_IIC0);
 272                 } else {
 273                         /* NACK, stop transmitting */
 274                         em_clear_set_bit(priv, 0, I2C_BIT_LREL0, I2C_OFS_IICC0);
 275                 }
 276         } else {
 277                 /* 8 bit interrupt mode */
 278                 em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_ACKE0,
 279                                 I2C_OFS_IICC0);
 280                 em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_WREL0,
 281                                 I2C_OFS_IICC0);
 282 
 283                 if (status & I2C_BIT_STD0) {
 284                         i2c_slave_event(priv->slave, I2C_SLAVE_WRITE_REQUESTED,
 285                                         &value);
 286                 } else {
 287                         /* Recv data */
 288                         value = readb(priv->base + I2C_OFS_IIC0);
 289                         ret = i2c_slave_event(priv->slave,
 290                                         I2C_SLAVE_WRITE_RECEIVED, &value);
 291                         if (ret < 0)
 292                                 em_clear_set_bit(priv, I2C_BIT_ACKE0, 0,
 293                                                 I2C_OFS_IICC0);
 294                 }
 295         }
 296 
 297         return true;
 298 }
 299 
 300 static irqreturn_t em_i2c_irq_handler(int this_irq, void *dev_id)
 301 {
 302         struct em_i2c_device *priv = dev_id;
 303 
 304         if (em_i2c_slave_irq(priv))
 305                 return IRQ_HANDLED;
 306 
 307         complete(&priv->msg_done);
 308 
 309         return IRQ_HANDLED;
 310 }
 311 
 312 static u32 em_i2c_func(struct i2c_adapter *adap)
 313 {
 314         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SLAVE;
 315 }
 316 
 317 static int em_i2c_reg_slave(struct i2c_client *slave)
 318 {
 319         struct em_i2c_device *priv = i2c_get_adapdata(slave->adapter);
 320 
 321         if (priv->slave)
 322                 return -EBUSY;
 323 
 324         if (slave->flags & I2C_CLIENT_TEN)
 325                 return -EAFNOSUPPORT;
 326 
 327         priv->slave = slave;
 328 
 329         /* Set slave address */
 330         writeb(slave->addr << 1, priv->base + I2C_OFS_SVA0);
 331 
 332         return 0;
 333 }
 334 
 335 static int em_i2c_unreg_slave(struct i2c_client *slave)
 336 {
 337         struct em_i2c_device *priv = i2c_get_adapdata(slave->adapter);
 338 
 339         WARN_ON(!priv->slave);
 340 
 341         writeb(0, priv->base + I2C_OFS_SVA0);
 342 
 343         /*
 344          * Wait for interrupt to finish. New slave irqs cannot happen because we
 345          * cleared the slave address and, thus, only extension codes will be
 346          * detected which do not use the slave ptr.
 347          */
 348         synchronize_irq(priv->irq);
 349         priv->slave = NULL;
 350 
 351         return 0;
 352 }
 353 
 354 static const struct i2c_algorithm em_i2c_algo = {
 355         .master_xfer = em_i2c_xfer,
 356         .functionality = em_i2c_func,
 357         .reg_slave      = em_i2c_reg_slave,
 358         .unreg_slave    = em_i2c_unreg_slave,
 359 };
 360 
 361 static int em_i2c_probe(struct platform_device *pdev)
 362 {
 363         struct em_i2c_device *priv;
 364         struct resource *r;
 365         int ret;
 366 
 367         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 368         if (!priv)
 369                 return -ENOMEM;
 370 
 371         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 372         priv->base = devm_ioremap_resource(&pdev->dev, r);
 373         if (IS_ERR(priv->base))
 374                 return PTR_ERR(priv->base);
 375 
 376         strlcpy(priv->adap.name, "EMEV2 I2C", sizeof(priv->adap.name));
 377 
 378         priv->sclk = devm_clk_get(&pdev->dev, "sclk");
 379         if (IS_ERR(priv->sclk))
 380                 return PTR_ERR(priv->sclk);
 381 
 382         ret = clk_prepare_enable(priv->sclk);
 383         if (ret)
 384                 return ret;
 385 
 386         priv->adap.timeout = msecs_to_jiffies(100);
 387         priv->adap.retries = 5;
 388         priv->adap.dev.parent = &pdev->dev;
 389         priv->adap.algo = &em_i2c_algo;
 390         priv->adap.owner = THIS_MODULE;
 391         priv->adap.dev.of_node = pdev->dev.of_node;
 392 
 393         init_completion(&priv->msg_done);
 394 
 395         platform_set_drvdata(pdev, priv);
 396         i2c_set_adapdata(&priv->adap, priv);
 397 
 398         em_i2c_reset(&priv->adap);
 399 
 400         priv->irq = platform_get_irq(pdev, 0);
 401         ret = devm_request_irq(&pdev->dev, priv->irq, em_i2c_irq_handler, 0,
 402                                 "em_i2c", priv);
 403         if (ret)
 404                 goto err_clk;
 405 
 406         ret = i2c_add_adapter(&priv->adap);
 407 
 408         if (ret)
 409                 goto err_clk;
 410 
 411         dev_info(&pdev->dev, "Added i2c controller %d, irq %d\n", priv->adap.nr,
 412                  priv->irq);
 413 
 414         return 0;
 415 
 416 err_clk:
 417         clk_disable_unprepare(priv->sclk);
 418         return ret;
 419 }
 420 
 421 static int em_i2c_remove(struct platform_device *dev)
 422 {
 423         struct em_i2c_device *priv = platform_get_drvdata(dev);
 424 
 425         i2c_del_adapter(&priv->adap);
 426         clk_disable_unprepare(priv->sclk);
 427 
 428         return 0;
 429 }
 430 
 431 static const struct of_device_id em_i2c_ids[] = {
 432         { .compatible = "renesas,iic-emev2", },
 433         { }
 434 };
 435 
 436 static struct platform_driver em_i2c_driver = {
 437         .probe = em_i2c_probe,
 438         .remove = em_i2c_remove,
 439         .driver = {
 440                 .name = "em-i2c",
 441                 .of_match_table = em_i2c_ids,
 442         }
 443 };
 444 module_platform_driver(em_i2c_driver);
 445 
 446 MODULE_DESCRIPTION("EMEV2 I2C bus driver");
 447 MODULE_AUTHOR("Ian Molton and Wolfram Sang <wsa@sang-engineering.com>");
 448 MODULE_LICENSE("GPL v2");
 449 MODULE_DEVICE_TABLE(of, em_i2c_ids);