i2c-s3c2410.c

嵌入式arm-linux 2.6内核 s3c2410 的i2c总线驱动程序

/* linux/drivers/i2c/busses/i2c-s3c2410.c 
 * 
 * Copyright (C) 2004,2005 Simtec Electronics 
 * Ben Dooks <[e-mail]> 
 * 
 * S3C2410 I2C Controller 
 * 
 * This program is free software; you can redistribute it and/or modify 
 * it under the terms of the GNU General Public License as published by 
 * the Free Software Foundation; either version 2 of the License, or 
 * (at your option) any later version. 
 * 
 * This program is distributed in the hope that it will be useful, 
 * but WITHOUT ANY WARRANTY; without even the implied warranty of 
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * GNU General Public License for more details. 
 * 
 * You should have received a copy of the GNU General Public License 
 * along with this program; if not, write to the Free Software 
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
*/ 

#include <linux/config.h> 
#include <linux/kernel.h> 
#include <linux/module.h> 

#include <linux/i2c.h> 
#include <linux/i2c-id.h> 
#include <linux/init.h> 
#include <linux/time.h> 
#include <linux/interrupt.h> 
#include <linux/sched.h> 
#include <linux/delay.h> 
#include <linux/errno.h> 
#include <linux/err.h> 
#include <linux/platform_device.h> 

#include <asm/hardware.h> 
#include <asm/irq.h> 
#include <asm/io.h> 

#include <asm/hardware/clock.h> 
#include <asm/arch/regs-gpio.h> 
#include <asm/arch/regs-iic.h> 
#include <asm/arch/iic.h> 

/* i2c controller state */ 

enum s3c24xx_i2c_state { 
 STATE_IDLE, 
 STATE_START, 
 STATE_READ, 
 STATE_WRITE, 
 STATE_STOP 
}; 

struct s3c24xx_i2c { 
 spinlock_t  lock; 
 wait_queue_head_t wait; 

 struct i2c_msg  *msg; 
 unsigned int  msg_num; 
 unsigned int  msg_idx; 
 unsigned int  msg_ptr; 

 enum s3c24xx_i2c_state state; 

 void __iomem  *regs; 
 struct clk  *clk; 
 struct device  *dev; 
 struct resource  *irq; 
 struct resource  *ioarea; 
 struct i2c_adapter adap; 
}; 

/* default platform data to use if not supplied in the platform_device 
*/ 

static struct s3c2410_platform_i2c s3c24xx_i2c_default_platform = { 
 .flags  = 0, 
 .slave_addr = 0x10, 
 .bus_freq = 100*1000, 
 .max_freq = 400*1000, 
 .sda_delay = S3C2410_IICLC_SDA_DELAY5 | S3C2410_IICLC_FILTER_ON, 
}; 

/* s3c24xx_i2c_is2440() 
 * 
 * return true is this is an s3c2440 
*/ 

static inline int s3c24xx_i2c_is2440(struct s3c24xx_i2c *i2c) 
{ 
 struct platform_device *pdev = to_platform_device(i2c->dev); 

 return !strcmp(pdev->name, "s3c2440-i2c"); 
} 


/* s3c24xx_i2c_get_platformdata 
 * 
 * get the platform data associated with the given device, or return 
 * the default if there is none 
*/ 

static inline struct s3c2410_platform_i2c *s3c24xx_i2c_get_platformdata(
struct device *dev) 
{ 
 if (dev->platform_data != NULL) 
  return (struct s3c2410_platform_i2c *)dev->platform_data; 

 return &s3c24xx_i2c_default_platform; 
} 

/* s3c24xx_i2c_master_complete 
 * 
 * complete the message and wake up the caller, using the given return code, 
 * or zero to mean ok. 
*/ 

static inline void s3c24xx_i2c_master_complete(struct s3c24xx_i2c *i2c, int 
ret) 
{ 
 dev_dbg(i2c->dev, "master_complete %d\n", ret); 

 i2c->msg_ptr = 0; 
 i2c->msg = NULL; 
 i2c->msg_idx ++; 
 i2c->msg_num = 0; 
 if (ret) 
  i2c->msg_idx = ret; 

 wake_up(&i2c->wait); 
} 

static inline void s3c24xx_i2c_disable_ack(struct s3c24xx_i2c *i2c) 
{ 
 unsigned long tmp; 
  
 tmp = readl(i2c->regs + S3C2410_IICCON); 
 writel(tmp & ~S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON); 

} 

static inline void s3c24xx_i2c_enable_ack(struct s3c24xx_i2c *i2c) 
{ 
 unsigned long tmp; 
  
 tmp = readl(i2c->regs + S3C2410_IICCON); 
 writel(tmp | S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON); 

} 

/* irq enable/disable functions */ 

static inline void s3c24xx_i2c_disable_irq(struct s3c24xx_i2c *i2c) 
{ 
 unsigned long tmp; 
  
 tmp = readl(i2c->regs + S3C2410_IICCON); 
 writel(tmp & ~S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON); 
} 

static inline void s3c24xx_i2c_enable_irq(struct s3c24xx_i2c *i2c) 
{ 
 unsigned long tmp; 
  
 tmp = readl(i2c->regs + S3C2410_IICCON); 
 writel(tmp | S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON); 
} 


/* s3c24xx_i2c_message_start 
 * 
 * put the start of a message onto the bus  
*/ 

static void s3c24xx_i2c_message_start(struct s3c24xx_i2c *i2c,  
          struct i2c_msg *msg) 
{ 
 unsigned int addr = (msg->addr & 0x7f) << 1; 
 unsigned long stat; 
 unsigned long iiccon; 

 stat = 0; 
 stat |=  S3C2410_IICSTAT_TXRXEN; 

 if (msg->flags & I2C_M_RD) { 
  stat |= S3C2410_IICSTAT_MASTER_RX; 
  addr |= 1; 
 } else 
  stat |= S3C2410_IICSTAT_MASTER_TX; 

 if (msg->flags & I2C_M_REV_DIR_ADDR) 
  addr ^= 1; 

 // todo - check for wether ack wanted or not 
 s3c24xx_i2c_enable_ack(i2c); 

 iiccon = readl(i2c->regs + S3C2410_IICCON); 
 writel(stat, i2c->regs + S3C2410_IICSTAT); 
  
 dev_dbg(i2c->dev, "START: %08lx to IICSTAT, %02x to DS\n", stat, addr); 
 writeb(addr, i2c->regs + S3C2410_IICDS); 
  
 // delay a bit and reset iiccon before setting start (per samsung) 
 udelay(1); 
 dev_dbg(i2c->dev, "iiccon, %08lx\n", iiccon); 
 writel(iiccon, i2c->regs + S3C2410_IICCON); 
  
 stat |=  S3C2410_IICSTAT_START; 
 writel(stat, i2c->regs + S3C2410_IICSTAT); 
} 

static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret) 
{ 
 unsigned long iicstat = readl(i2c->regs + S3C2410_IICSTAT); 

 dev_dbg(i2c->dev, "STOP\n"); 

 /* stop the transfer */ 
 iicstat &= ~ S3C2410_IICSTAT_START; 
 writel(iicstat, i2c->regs + S3C2410_IICSTAT); 
  
 i2c->state = STATE_STOP; 
  
 s3c24xx_i2c_master_complete(i2c, ret); 
 s3c24xx_i2c_disable_irq(i2c); 
} 

/* helper functions to determine the current state in the set of 
 * messages we are sending */ 

/* is_lastmsg() 
 * 
 * returns TRUE if the current message is the last in the set  
*/ 

static inline int is_lastmsg(struct s3c24xx_i2c *i2c) 
{ 
 return i2c->msg_idx >= (i2c->msg_num - 1); 
} 

/* is_msglast 
 * 
 * returns TRUE if we this is the last byte in the current message 
*/ 

static inline int is_msglast(struct s3c24xx_i2c *i2c) 
{ 
 return i2c->msg_ptr == i2c->msg->len-1; 
} 

/* is_msgend 
 * 
 * returns TRUE if we reached the end of the current message 
*/ 

static inline int is_msgend(struct s3c24xx_i2c *i2c) 
{ 
 return i2c->msg_ptr >= i2c->msg->len; 
} 

/* i2s_s3c_irq_nextbyte 
 * 
 * process an interrupt and work out what to do 
 */ 

static int i2s_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat
) 
{ 
 unsigned long tmp; 
 unsigned char byte; 
 int ret = 0; 

 switch (i2c->state) { 

 case STATE_IDLE: 
  dev_err(i2c->dev, "%s: called in STATE_IDLE\n", __FUNCTION__); 
  goto out; 
  break; 

 case STATE_STOP: 
  dev_err(i2c->dev, "%s: called in STATE_STOP\n", __FUNCTION__); 
  s3c24xx_i2c_disable_irq(i2c);   
  goto out_ack; 

 case STATE_START: 
  /* last thing we did was send a start condition on the 
   * bus, or started a new i2c message 
   */ 
   
  if (iicstat  & S3C2410_IICSTAT_LASTBIT && 
      !(i2c->msg->flags & I2C_M_IGNORE_NAK)) { 
   /* ack was not received... */ 

   dev_dbg(i2c->dev, "ack was not received\n"); 
   s3c24xx_i2c_stop(i2c, -EREMOTEIO); 
   goto out_ack; 
  } 

  if (i2c->msg->flags & I2C_M_RD) 
   i2c->state = STATE_READ; 
  else 
   i2c->state = STATE_WRITE; 

  /* terminate the transfer if there is nothing to do 
   * (used by the i2c probe to find devices */ 

  if (is_lastmsg(i2c) && i2c->msg->len == 0) { 
   s3c24xx_i2c_stop(i2c, 0); 
   goto out_ack; 
  } 

  if (i2c->state == STATE_READ) 
   goto prepare_read; 

  /* fall through to the write state, as we will need to  
   * send a byte as well */ 

 case STATE_WRITE: 
  /* we are writing data to the device... check for the 
   * end of the message, and if so, work out what to do 
   */ 

 retry_write: 
  if (!is_msgend(i2c)) { 
   byte = i2c->msg->buf[i2c->msg_ptr++]; 
   writeb(byte, i2c->regs + S3C2410_IICDS); 
    
  } else if (!is_lastmsg(i2c)) { 
   /* we need to go to the next i2c message */ 

   dev_dbg(i2c->dev, "WRITE: Next Message\n"); 

   i2c->msg_ptr = 0; 
   i2c->msg_idx ++; 
   i2c->msg++; 
    
   /* check to see if we need to do another message */ 
   if (i2c->msg->flags & I2C_M_NOSTART) { 

    if (i2c->msg->flags & I2C_M_RD) { 
     /* cannot do this, the controller 
      * forces us to send a new START 
      * when we change direction */ 

     s3c24xx_i2c_stop(i2c, -EINVAL); 
    } 

    goto retry_write; 
   } else { 
    
    /* send the new start */ 
    s3c24xx_i2c_message_start(i2c, i2c->msg); 
    i2c->state = STATE_START; 
   } 

  } else { 
   /* send stop */ 

   s3c24xx_i2c_stop(i2c, 0); 
  } 
  break; 

 case STATE_READ: 
  /* we have a byte of data in the data register, do  
   * something with it, and then work out wether we are 
   * going to do any more read/write 
   */ 

  if (!(i2c->msg->flags & I2C_M_IGNORE_NAK) && 
      !(is_msglast(i2c) && is_lastmsg(i2c))) { 

   if (iicstat & S3C2410_IICSTAT_LASTBIT) { 
    dev_dbg(i2c->dev, "READ: No Ack\n"); 

    s3c24xx_i2c_stop(i2c, -ECONNREFUSED); 
    goto out_ack; 
   } 
  } 

  byte = readb(i2c->regs + S3C2410_IICDS); 
  i2c->msg->buf[i2c->msg_ptr++] = byte; 



prepare_read: 
  if (is_msglast(i2c)) { 
   /* last byte of buffer */ 

   if (is_lastmsg(i2c)) 
    s3c24xx_i2c_disable_ack(i2c); 
    
  } else if (is_msgend(i2c)) { 
   /* ok, we’ve read the entire buffer, see if there 
    * is anything else we need to do */ 

   if (is_lastmsg(i2c)) { 
    /* last message, send stop and complete */ 
    dev_dbg(i2c->dev, "READ: Send Stop\n"); 

    s3c24xx_i2c_stop(i2c, 0); 
   } else { 
    /* go to the next transfer */ 
    dev_dbg(i2c->dev, "READ: Next Transfer\n"); 

    i2c->msg_ptr = 0; 
    i2c->msg_idx++; 
    i2c->msg++; 
   } 
  } 

  break; 
 } 

 /* acknowlegde the IRQ and get back on with the work */ 

 out_ack: 
 tmp = readl(i2c->regs + S3C2410_IICCON);  
 tmp &= ~S3C2410_IICCON_IRQPEND; 
 writel(tmp, i2c->regs + S3C2410_IICCON); 
 out: 
 return ret; 
} 

/* s3c24xx_i2c_irq 
 * 
 * top level IRQ servicing routine 
*/ 

static irqreturn_t s3c24xx_i2c_irq(int irqno, void *dev_id, 
       struct pt_regs *regs) 
{ 
 struct s3c24xx_i2c *i2c = dev_id; 
 unsigned long status; 
 unsigned long tmp; 

 status = readl(i2c->regs + S3C2410_IICSTAT); 

 if (status & S3C2410_IICSTAT_ARBITR) { 
  // deal with arbitration loss 
  dev_err(i2c->dev, "deal with arbitration loss\n"); 
 } 

 if (i2c->state == STATE_IDLE) { 
  dev_dbg(i2c->dev, "IRQ: error i2c->state == IDLE\n"); 

  tmp = readl(i2c->regs + S3C2410_IICCON);  
  tmp &= ~S3C2410_IICCON_IRQPEND; 
  writel(tmp, i2c->regs +  S3C2410_IICCON); 
  goto out; 
 } 
  
 /* pretty much this leaves us with the fact that we’ve 
  * transmitted or received whatever byte we last sent */ 

 i2s_s3c_irq_nextbyte(i2c, status); 

 out: 
 return IRQ_HANDLED; 
} 


/* s3c24xx_i2c_set_master 
 * 
 * get the i2c bus for a master transaction 
*/ 

static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c) 
{ 
 unsigned long iicstat; 
 int timeout = 400; 

 while (timeout-- > 0) { 
  iicstat = readl(i2c->regs + S3C2410_IICSTAT);