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mxc_i2c_slave.c

/*
 * Copyright 2007-2008 Freescale Semiconductor, Inc. All Rights Reserved.
 */

/*
 * The code contained herein is licensed under the GNU General Public
 * License. You may obtain a copy of the GNU General Public License
 * Version 2 or later at the following locations:
 *
 * http://www.opensource.org/licenses/gpl-license.html
 * http://www.gnu.org/copyleft/gpl.html
 */

#include <asm/io.h>
#include <linux/pm.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include "i2c_slave_device.h"
#include "mxc_i2c_slave.h"
#include "mxc_i2c_slave_reg.h"

struct mxc_i2c_slave_clk {
      int reg_value;
      int div;
};

static const struct mxc_i2c_slave_clk i2c_clk_table[] = {
      {0x20, 22}, {0x21, 24}, {0x22, 26}, {0x23, 28},
      {0, 30}, {1, 32}, {0x24, 32}, {2, 36},
      {0x25, 36}, {0x26, 40}, {3, 42}, {0x27, 44},
      {4, 48}, {0x28, 48}, {5, 52}, {0x29, 56},
      {6, 60}, {0x2A, 64}, {7, 72}, {0x2B, 72},
      {8, 80}, {0x2C, 80}, {9, 88}, {0x2D, 96},
      {0xA, 104}, {0x2E, 112}, {0xB, 128}, {0x2F, 128},
      {0xC, 144}, {0xD, 160}, {0x30, 160}, {0xE, 192},
      {0x31, 192}, {0x32, 224}, {0xF, 240}, {0x33, 256},
      {0x10, 288}, {0x11, 320}, {0x34, 320}, {0x12, 384},
      {0x35, 384}, {0x36, 448}, {0x13, 480}, {0x37, 512},
      {0x14, 576}, {0x15, 640}, {0x38, 640}, {0x16, 768},
      {0x39, 768}, {0x3A, 896}, {0x17, 960}, {0x3B, 1024},
      {0x18, 1152}, {0x19, 1280}, {0x3C, 1280}, {0x1A, 1536},
      {0x3D, 1536}, {0x3E, 1792}, {0x1B, 1920}, {0x3F, 2048},
      {0x1C, 2304}, {0x1D, 2560}, {0x1E, 3072}, {0x1F, 3840},
      {0, 0}
};

extern void gpio_i2c_active(int i2c_num);
extern void gpio_i2c_inactive(int i2c_num);

static irqreturn_t interrupt_handler(int irq, void *dev_id)
{
      u16 status, ctl;
      int num;
      u16 data;
      struct mxc_i2c_slave_device *mxc_i2c =
          (struct mxc_i2c_slave_device *)dev_id;

      status = readw(mxc_i2c->reg_base + MXC_I2SR);
      ctl = readw(mxc_i2c->reg_base + MXC_I2CR);

      dev_dbg(mxc_i2c->dev->dev, "status=%x, ctl=%x\n", status, ctl);

      if (status & MXC_I2SR_IAAS) {
            if (status & MXC_I2SR_SRW) {
                  /*slave send */
                  num =
                      i2c_slave_device_consume(mxc_i2c->dev, 1,
                                         (u8 *) &data);
                  if (num < 1) {
                        /*FIXME:not ready to send data */
                        printk(KERN_ERR
                               " i2c-slave:%s:data not ready\n",
                               __func__);
                  } else {
                        ctl |= MXC_I2CR_MTX;
                        writew(ctl, mxc_i2c->reg_base + MXC_I2CR);
                        /*send data */
                        writew(data, mxc_i2c->reg_base + MXC_I2DR);
                  }

            } else {
                  /*slave receive */
                  ctl &= ~MXC_I2CR_MTX;
                  writew(ctl, mxc_i2c->reg_base + MXC_I2CR);

                  /*dummy read */
                  data = readw(mxc_i2c->reg_base + MXC_I2DR);
            }
      } else {
            /*slave send */
            if (ctl & MXC_I2CR_MTX) {
                  if (!(status & MXC_I2SR_RXAK)) {    /*ACK received */
                        num =
                            i2c_slave_device_consume(mxc_i2c->dev, 1,
                                               (u8 *) &data);
                        if (num < 1) {
                              /*FIXME:not ready to send data */
                              printk(KERN_ERR
                                     " i2c-slave:%s:data not ready\n",
                                     __func__);
                        } else {
                              ctl |= MXC_I2CR_MTX;
                              writew(ctl,
                                     mxc_i2c->reg_base + MXC_I2CR);
                              writew(data,
                                     mxc_i2c->reg_base + MXC_I2DR);
                        }
                  } else {
                        /*no ACK. */
                        /*dummy read */
                        ctl &= ~MXC_I2CR_MTX;
                        writew(ctl, mxc_i2c->reg_base + MXC_I2CR);
                        data = readw(mxc_i2c->reg_base + MXC_I2DR);
                  }
            } else {    /*read */
                  ctl &= ~MXC_I2CR_MTX;
                  writew(ctl, mxc_i2c->reg_base + MXC_I2CR);

                  /*read */
                  data = readw(mxc_i2c->reg_base + MXC_I2DR);
                  i2c_slave_device_produce(mxc_i2c->dev, 1,
                                     (u8 *) &data);
            }

      }

      writew(0x0, mxc_i2c->reg_base + MXC_I2SR);

      return IRQ_HANDLED;
}

static int start(i2c_slave_device_t *device)
{
      volatile unsigned int cr;
      unsigned int addr;
      struct mxc_i2c_slave_device *mxc_dev;

      mxc_dev = (struct mxc_i2c_slave_device *)device->private_data;
      if (!mxc_dev) {
            dev_err(device->dev, "%s: get mxc_dev error\n", __func__);
            return -ENODEV;
      }

      clk_enable(mxc_dev->clk);
      /* Set the frequency divider */
      writew(mxc_dev->clkdiv, mxc_dev->reg_base + MXC_IFDR);

      /* Set the Slave bit */
      cr = readw(mxc_dev->reg_base + MXC_I2CR);
      cr &= (!MXC_I2CR_MSTA);
      writew(cr, mxc_dev->reg_base + MXC_I2CR);

      /*Set Slave Address */
      addr = mxc_dev->dev->address << 1;
      writew(addr, mxc_dev->reg_base + MXC_IADR);

      /* Clear the status register */
      writew(0x0, mxc_dev->reg_base + MXC_I2SR);

      /* Enable I2C and its interrupts */
      writew(MXC_I2CR_IEN, mxc_dev->reg_base + MXC_I2CR);
      writew(MXC_I2CR_IEN | MXC_I2CR_IIEN, mxc_dev->reg_base + MXC_I2CR);

      return 0;

}

static int stop(i2c_slave_device_t *device)
{
      struct mxc_i2c_slave_device *mxc_dev;

      mxc_dev = (struct mxc_i2c_slave_device *)device->private_data;

      writew(0x0, mxc_dev->reg_base + MXC_I2CR);
      clk_disable(mxc_dev->clk);

      return 0;
}

static int mxc_i2c_slave_probe(struct platform_device *pdev)
{
      int i;
      u32 clk_freq;
      struct resource *res;
      struct mxc_i2c_slave_device *mxc_dev;

      mxc_dev = kzalloc(sizeof(struct mxc_i2c_slave_device), GFP_KERNEL);
      if (!mxc_dev) {
            goto error0;
      }
      mxc_dev->dev = i2c_slave_device_alloc();
      if (mxc_dev->dev == 0) {
            dev_err(&pdev->dev, "%s: i2c_slave_device_alloc error\n",
                  __func__);
            goto error1;
      }

      i2c_slave_device_set_address(mxc_dev->dev, MXC_I2C_SLAVE_ADDRESS);
      i2c_slave_device_set_freq(mxc_dev->dev, MXC_I2C_SLAVE_FREQ);
      i2c_slave_device_set_name(mxc_dev->dev, MXC_I2C_SLAVE_NAME);
      mxc_dev->dev->start = start;
      mxc_dev->dev->stop = stop;

      mxc_dev->dev->private_data = mxc_dev;

      res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
      if (res == NULL) {
            dev_err(&pdev->dev, "%s: get resource error\n", __func__);
            goto error2;
      }
      mxc_dev->reg_base = IO_ADDRESS(res->start);

      mxc_dev->irq = platform_get_irq(pdev, 0);
      if (mxc_dev->irq < 0) {
            dev_err(&pdev->dev, "%s: get irq error\n", __func__);
            goto error2;
      }
      if (request_irq(mxc_dev->irq, interrupt_handler,
                  0, mxc_dev->dev->name, mxc_dev) < 0) {
            dev_err(&pdev->dev, "%s: request_irq error\n", __func__);
            goto error2;
      }

      /*i2c id on soc */
      mxc_dev->id = pdev->id;

      gpio_i2c_active(mxc_dev->id);

      /*clock */
      mxc_dev->clk = clk_get(&pdev->dev, "i2c_clk");
      clk_freq = clk_get_rate(mxc_dev->clk);
      mxc_dev->clkdiv = -1;
      if (mxc_dev->dev->scl_freq) {
            /* Calculate divider and round up any fractional part */
            int div = (clk_freq + mxc_dev->dev->scl_freq - 1) /
                mxc_dev->dev->scl_freq;
            for (i = 0; i2c_clk_table[i].div != 0; i++) {
                  if (i2c_clk_table[i].div >= div) {
                        mxc_dev->clkdiv = i2c_clk_table[i].reg_value;
                        break;
                  }
            }
      }
      if (mxc_dev->clkdiv == -1) {
            i--;
            mxc_dev->clkdiv = 0x1F; /* Use max divider */
      }
      dev_dbg(&pdev->dev,
            "i2c slave speed is %d/%d = %d bps, reg val = 0x%02X\n",
            clk_freq, i2c_clk_table[i].div, clk_freq / i2c_clk_table[i].div,
            mxc_dev->clkdiv);

      if (i2c_slave_device_register(mxc_dev->dev) < 0) {
            dev_err(&pdev->dev, "%s: i2c_slave_device_register error\n",
                  __func__);
            goto error3;
      }

      platform_set_drvdata(pdev, (void *)mxc_dev);

      /*start(mxc_dev->dev); */
      return 0;

      error3:
      error2:
      i2c_slave_device_free(mxc_dev->dev);
      error1:
      kfree(mxc_dev);
      error0:
      return -ENODEV;
}

static int mxc_i2c_slave_remove(struct platform_device *pdev)
{
      struct mxc_i2c_slave_device *mxc_dev;
      mxc_dev = (struct mxc_i2c_slave_device *)platform_get_drvdata(pdev);

      i2c_slave_device_unregister(mxc_dev->dev);
      kfree((void *)mxc_dev);

      return 0;
}

static int mxc_i2c_slave_suspend(struct platform_device *pdev,
                         pm_message_t state)
{
      return 0;
}

static int mxc_i2c_slave_resume(struct platform_device *pdev)
{
      return 0;
}

static struct platform_driver mxci2c_slave_driver = {
      .driver = {
               .name = "mxc_i2c_slave",
               .owner = THIS_MODULE,
               },
      .probe = mxc_i2c_slave_probe,
      .remove = mxc_i2c_slave_remove,
      .suspend = mxc_i2c_slave_suspend,
      .resume = mxc_i2c_slave_resume,
};

static int __init mxc_i2c_slave_init(void)
{
      /* Register the device driver structure. */
      return platform_driver_register(&mxci2c_slave_driver);
}

/*!
 * This function is used to cleanup all resources before the driver exits.
 */
static void __exit mxc_i2c_slave_exit(void)
{
      platform_driver_unregister(&mxci2c_slave_driver);
}

module_init(mxc_i2c_slave_init);
module_exit(mxc_i2c_slave_exit);

MODULE_AUTHOR("Freescale Semiconductor, Inc.");
MODULE_DESCRIPTION("MXC I2C Slave Driver");
MODULE_LICENSE("GPL");

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