/*
   * Flash memory interface rev.5 driver for the Intel
   * Flash chips used on the NetWinder.
   *
   * 20/08/2000	RMK	use __ioremap to map flash into virtual memory
   *			make a few more places use "volatile"
   * 22/05/2001	RMK	- Lock read against write
   *			- merge printk level changes (with mods) from Alan Cox.
   *			- use *ppos as the file position, not file->f_pos.
   *			- fix check for out of range pos and r/w size
   *
   * Please note that we are tampering with the only flash chip in the
   * machine, which contains the bootup code.  We therefore have the
   * power to convert these machines into doorstops...
   */
  
  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/fs.h>
  #include <linux/errno.h>
  #include <linux/mm.h>
  #include <linux/delay.h>
  #include <linux/proc_fs.h>
  #include <linux/miscdevice.h>
  #include <linux/spinlock.h>
  #include <linux/rwsem.h>
  #include <linux/init.h>
  #include <linux/mutex.h>
  #include <linux/jiffies.h>
  
  #include <asm/hardware/dec21285.h>
  #include <asm/io.h>
  #include <asm/mach-types.h>
  #include <asm/uaccess.h>
  
  /*****************************************************************************/
  #include <asm/nwflash.h>
  
  #define	NWFLASH_VERSION "6.4"
  
  static DEFINE_MUTEX(flash_mutex);
  static void kick_open(void);
  static int get_flash_id(void);
  static int erase_block(int nBlock);
  static int write_block(unsigned long p, const char __user *buf, int count);
  
  #define KFLASH_SIZE	1024*1024	//1 Meg
  #define KFLASH_SIZE4	4*1024*1024	//4 Meg
  #define KFLASH_ID	0x89A6		//Intel flash
  #define KFLASH_ID4	0xB0D4		//Intel flash 4Meg
  
  static bool flashdebug;		//if set - we will display progress msgs
  
  static int gbWriteEnable;
  static int gbWriteBase64Enable;
  static volatile unsigned char *FLASH_BASE;
  static int gbFlashSize = KFLASH_SIZE;
  static DEFINE_MUTEX(nwflash_mutex);
  
  static int get_flash_id(void)
  {
  	volatile unsigned int c1, c2;
  
  	/*
  	 * try to get flash chip ID
  	 */
  	kick_open();
  	c2 = inb(0x80);
  	*(volatile unsigned char *) (FLASH_BASE + 0x8000) = 0x90;
  	udelay(15);
  	c1 = *(volatile unsigned char *) FLASH_BASE;
  	c2 = inb(0x80);
  
  	/*
  	 * on 4 Meg flash the second byte is actually at offset 2...
  	 */
  	if (c1 == 0xB0)
  		c2 = *(volatile unsigned char *) (FLASH_BASE + 2);
  	else
  		c2 = *(volatile unsigned char *) (FLASH_BASE + 1);
  
  	c2 += (c1 << 8);
  
  	/*
  	 * set it back to read mode
  	 */
  	*(volatile unsigned char *) (FLASH_BASE + 0x8000) = 0xFF;
  
  	if (c2 == KFLASH_ID4)
  		gbFlashSize = KFLASH_SIZE4;
  
  	return c2;
  }
  
  static long flash_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
  {
  	mutex_lock(&flash_mutex);
  	switch (cmd) {
  	case CMD_WRITE_DISABLE:
  		gbWriteBase64Enable = 0;
  		gbWriteEnable = 0;
  		break;
  
  	case CMD_WRITE_ENABLE:
  		gbWriteEnable = 1;
  		break;
  
  	case CMD_WRITE_BASE64K_ENABLE:
  		gbWriteBase64Enable = 1;
  		break;
  
  	default:
  		gbWriteBase64Enable = 0;
  		gbWriteEnable = 0;
  		mutex_unlock(&flash_mutex);
  		return -EINVAL;
  	}
  	mutex_unlock(&flash_mutex);
  	return 0;
  }
  
  static ssize_t flash_read(struct file *file, char __user *buf, size_t size,
  			  loff_t *ppos)
  {
  	ssize_t ret;
  
  	if (flashdebug)
  		printk(KERN_DEBUG "flash_read: flash_read: offset=0x%llx, "
  		       "buffer=%p, count=0x%zx.
  ", *ppos, buf, size);
  	/*
  	 * We now lock against reads and writes. --rmk
  	 */
  	if (mutex_lock_interruptible(&nwflash_mutex))
  		return -ERESTARTSYS;
  
  	ret = simple_read_from_buffer(buf, size, ppos, (void *)FLASH_BASE, gbFlashSize);
  	mutex_unlock(&nwflash_mutex);
  
  	return ret;
  }
  
  static ssize_t flash_write(struct file *file, const char __user *buf,
  			   size_t size, loff_t * ppos)
  {
  	unsigned long p = *ppos;
  	unsigned int count = size;
  	int written;
  	int nBlock, temp, rc;
  	int i, j;
  
  	if (flashdebug)
  		printk("flash_write: offset=0x%lX, buffer=0x%p, count=0x%X.
  ",
  		       p, buf, count);
  
  	if (!gbWriteEnable)
  		return -EINVAL;
  
  	if (p < 64 * 1024 && (!gbWriteBase64Enable))
  		return -EINVAL;
  
  	/*
  	 * check for out of range pos or count
  	 */
  	if (p >= gbFlashSize)
  		return count ? -ENXIO : 0;
  
  	if (count > gbFlashSize - p)
  		count = gbFlashSize - p;
  			
  	if (!access_ok(VERIFY_READ, buf, count))
  		return -EFAULT;
  
  	/*
  	 * We now lock against reads and writes. --rmk
  	 */
  	if (mutex_lock_interruptible(&nwflash_mutex))
  		return -ERESTARTSYS;
  
  	written = 0;
  
  	nBlock = (int) p >> 16;	//block # of 64K bytes
  
  	/*
  	 * # of 64K blocks to erase and write
  	 */
  	temp = ((int) (p + count) >> 16) - nBlock + 1;
  
  	/*
  	 * write ends at exactly 64k boundary?
  	 */
  	if (((int) (p + count) & 0xFFFF) == 0)
  		temp -= 1;
  
  	if (flashdebug)
  		printk(KERN_DEBUG "flash_write: writing %d block(s) "
  			"starting at %d.
  ", temp, nBlock);
  
  	for (; temp; temp--, nBlock++) {
  		if (flashdebug)
  			printk(KERN_DEBUG "flash_write: erasing block %d.
  ", nBlock);
  
  		/*
  		 * first we have to erase the block(s), where we will write...
  		 */
  		i = 0;
  		j = 0;
  	  RetryBlock:
  		do {
  			rc = erase_block(nBlock);
  			i++;
  		} while (rc && i < 10);
  
  		if (rc) {
  			printk(KERN_ERR "flash_write: erase error %x
  ", rc);
  			break;
  		}
  		if (flashdebug)
  			printk(KERN_DEBUG "flash_write: writing offset %lX, "
  			       "from buf %p, bytes left %X.
  ", p, buf,
  			       count - written);
  
  		/*
  		 * write_block will limit write to space left in this block
  		 */
  		rc = write_block(p, buf, count - written);
  		j++;
  
  		/*
  		 * if somehow write verify failed? Can't happen??
  		 */
  		if (!rc) {
  			/*
  			 * retry up to 10 times
  			 */
  			if (j < 10)
  				goto RetryBlock;
  			else
  				/*
  				 * else quit with error...
  				 */
  				rc = -1;
  
  		}
  		if (rc < 0) {
  			printk(KERN_ERR "flash_write: write error %X
  ", rc);
  			break;
  		}
  		p += rc;
  		buf += rc;
  		written += rc;
  		*ppos += rc;
  
  		if (flashdebug)
  			printk(KERN_DEBUG "flash_write: written 0x%X bytes OK.
  ", written);
  	}
  
  	mutex_unlock(&nwflash_mutex);
  
  	return written;
  }
  
  
  /*
   * The memory devices use the full 32/64 bits of the offset, and so we cannot
   * check against negative addresses: they are ok. The return value is weird,
   * though, in that case (0).
   *
   * also note that seeking relative to the "end of file" isn't supported:
   * it has no meaning, so it returns -EINVAL.
   */
  static loff_t flash_llseek(struct file *file, loff_t offset, int orig)
  {
  	loff_t ret;
  
  	mutex_lock(&flash_mutex);
  	if (flashdebug)
  		printk(KERN_DEBUG "flash_llseek: offset=0x%X, orig=0x%X.
  ",
  		       (unsigned int) offset, orig);
  
  	switch (orig) {
  	case 0:
  		if (offset < 0) {
  			ret = -EINVAL;
  			break;
  		}
  
  		if ((unsigned int) offset > gbFlashSize) {
  			ret = -EINVAL;
  			break;
  		}
  
  		file->f_pos = (unsigned int) offset;
  		ret = file->f_pos;
  		break;
  	case 1:
  		if ((file->f_pos + offset) > gbFlashSize) {
  			ret = -EINVAL;
  			break;
  		}
  		if ((file->f_pos + offset) < 0) {
  			ret = -EINVAL;
  			break;
  		}
  		file->f_pos += offset;
  		ret = file->f_pos;
  		break;
  	default:
  		ret = -EINVAL;
  	}
  	mutex_unlock(&flash_mutex);
  	return ret;
  }
  
  
  /*
   * assume that main Write routine did the parameter checking...
   * so just go ahead and erase, what requested!
   */
  
  static int erase_block(int nBlock)
  {
  	volatile unsigned int c1;
  	volatile unsigned char *pWritePtr;
  	unsigned long timeout;
  	int temp, temp1;
  
  	/*
  	 * reset footbridge to the correct offset 0 (...0..3)
  	 */
  	*CSR_ROMWRITEREG = 0;
  
  	/*
  	 * dummy ROM read
  	 */
  	c1 = *(volatile unsigned char *) (FLASH_BASE + 0x8000);
  
  	kick_open();
  	/*
  	 * reset status if old errors
  	 */
  	*(volatile unsigned char *) (FLASH_BASE + 0x8000) = 0x50;
  
  	/*
  	 * erase a block...
  	 * aim at the middle of a current block...
  	 */
  	pWritePtr = (unsigned char *) ((unsigned int) (FLASH_BASE + 0x8000 + (nBlock << 16)));
  	/*
  	 * dummy read
  	 */
  	c1 = *pWritePtr;
  
  	kick_open();
  	/*
  	 * erase
  	 */
  	*(volatile unsigned char *) pWritePtr = 0x20;
  
  	/*
  	 * confirm
  	 */
  	*(volatile unsigned char *) pWritePtr = 0xD0;
  
  	/*
  	 * wait 10 ms
  	 */
  	msleep(10);
  
  	/*
  	 * wait while erasing in process (up to 10 sec)
  	 */
  	timeout = jiffies + 10 * HZ;
  	c1 = 0;
  	while (!(c1 & 0x80) && time_before(jiffies, timeout)) {
  		msleep(10);
  		/*
  		 * read any address
  		 */
  		c1 = *(volatile unsigned char *) (pWritePtr);
  		//              printk("Flash_erase: status=%X.
  ",c1);
  	}
  
  	/*
  	 * set flash for normal read access
  	 */
  	kick_open();
  //      *(volatile unsigned char*)(FLASH_BASE+0x8000) = 0xFF;
  	*(volatile unsigned char *) pWritePtr = 0xFF;	//back to normal operation
  
  	/*
  	 * check if erase errors were reported
  	 */
  	if (c1 & 0x20) {
  		printk(KERN_ERR "flash_erase: err at %p
  ", pWritePtr);
  
  		/*
  		 * reset error
  		 */
  		*(volatile unsigned char *) (FLASH_BASE + 0x8000) = 0x50;
  		return -2;
  	}
  
  	/*
  	 * just to make sure - verify if erased OK...
  	 */
  	msleep(10);
  
  	pWritePtr = (unsigned char *) ((unsigned int) (FLASH_BASE + (nBlock << 16)));
  
  	for (temp = 0; temp < 16 * 1024; temp++, pWritePtr += 4) {
  		if ((temp1 = *(volatile unsigned int *) pWritePtr) != 0xFFFFFFFF) {
  			printk(KERN_ERR "flash_erase: verify err at %p = %X
  ",
  			       pWritePtr, temp1);
  			return -1;
  		}
  	}
  
  	return 0;
  
  }
  
  /*
   * write_block will limit number of bytes written to the space in this block
   */
  static int write_block(unsigned long p, const char __user *buf, int count)
  {
  	volatile unsigned int c1;
  	volatile unsigned int c2;
  	unsigned char *pWritePtr;
  	unsigned int uAddress;
  	unsigned int offset;
  	unsigned long timeout;
  	unsigned long timeout1;
  
  	pWritePtr = (unsigned char *) ((unsigned int) (FLASH_BASE + p));
  
  	/*
  	 * check if write will end in this block....
  	 */
  	offset = p & 0xFFFF;
  
  	if (offset + count > 0x10000)
  		count = 0x10000 - offset;
  
  	/*
  	 * wait up to 30 sec for this block
  	 */
  	timeout = jiffies + 30 * HZ;
  
  	for (offset = 0; offset < count; offset++, pWritePtr++) {
  		uAddress = (unsigned int) pWritePtr;
  		uAddress &= 0xFFFFFFFC;
  		if (__get_user(c2, buf + offset))
  			return -EFAULT;
  
  	  WriteRetry:
  	  	/*
  	  	 * dummy read
  	  	 */
  		c1 = *(volatile unsigned char *) (FLASH_BASE + 0x8000);
  
  		/*
  		 * kick open the write gate
  		 */
  		kick_open();
  
  		/*
  		 * program footbridge to the correct offset...0..3
  		 */
  		*CSR_ROMWRITEREG = (unsigned int) pWritePtr & 3;
  
  		/*
  		 * write cmd
  		 */
  		*(volatile unsigned char *) (uAddress) = 0x40;
  
  		/*
  		 * data to write
  		 */
  		*(volatile unsigned char *) (uAddress) = c2;
  
  		/*
  		 * get status
  		 */
  		*(volatile unsigned char *) (FLASH_BASE + 0x10000) = 0x70;
  
  		c1 = 0;
  
  		/*
  		 * wait up to 1 sec for this byte
  		 */
  		timeout1 = jiffies + 1 * HZ;
  
  		/*
  		 * while not ready...
  		 */
  		while (!(c1 & 0x80) && time_before(jiffies, timeout1))
  			c1 = *(volatile unsigned char *) (FLASH_BASE + 0x8000);
  
  		/*
  		 * if timeout getting status
  		 */
  		if (time_after_eq(jiffies, timeout1)) {
  			kick_open();
  			/*
  			 * reset err
  			 */
  			*(volatile unsigned char *) (FLASH_BASE + 0x8000) = 0x50;
  
  			goto WriteRetry;
  		}
  		/*
  		 * switch on read access, as a default flash operation mode
  		 */
  		kick_open();
  		/*
  		 * read access
  		 */
  		*(volatile unsigned char *) (FLASH_BASE + 0x8000) = 0xFF;
  
  		/*
  		 * if hardware reports an error writing, and not timeout - 
  		 * reset the chip and retry
  		 */
  		if (c1 & 0x10) {
  			kick_open();
  			/*
  			 * reset err
  			 */
  			*(volatile unsigned char *) (FLASH_BASE + 0x8000) = 0x50;
  
  			/*
  			 * before timeout?
  			 */
  			if (time_before(jiffies, timeout)) {
  				if (flashdebug)
  					printk(KERN_DEBUG "write_block: Retrying write at 0x%X)n",
  					       pWritePtr - FLASH_BASE);
  
  				/*
  				 * wait couple ms
  				 */
  				msleep(10);
  
  				goto WriteRetry;
  			} else {
  				printk(KERN_ERR "write_block: timeout at 0x%X
  ",
  				       pWritePtr - FLASH_BASE);
  				/*
  				 * return error -2
  				 */
  				return -2;
  
  			}
  		}
  	}
  
  	msleep(10);
  
  	pWritePtr = (unsigned char *) ((unsigned int) (FLASH_BASE + p));
  
  	for (offset = 0; offset < count; offset++) {
  		char c, c1;
  		if (__get_user(c, buf))
  			return -EFAULT;
  		buf++;
  		if ((c1 = *pWritePtr++) != c) {
  			printk(KERN_ERR "write_block: verify error at 0x%X (%02X!=%02X)
  ",
  			       pWritePtr - FLASH_BASE, c1, c);
  			return 0;
  		}
  	}
  
  	return count;
  }
  
  
  static void kick_open(void)
  {
  	unsigned long flags;
  
  	/*
  	 * we want to write a bit pattern XXX1 to Xilinx to enable
  	 * the write gate, which will be open for about the next 2ms.
  	 */
  	raw_spin_lock_irqsave(&nw_gpio_lock, flags);
  	nw_cpld_modify(CPLD_FLASH_WR_ENABLE, CPLD_FLASH_WR_ENABLE);
  	raw_spin_unlock_irqrestore(&nw_gpio_lock, flags);
  
  	/*
  	 * let the ISA bus to catch on...
  	 */
  	udelay(25);
  }
  
  static const struct file_operations flash_fops =
  {
  	.owner		= THIS_MODULE,
  	.llseek		= flash_llseek,
  	.read		= flash_read,
  	.write		= flash_write,
  	.unlocked_ioctl	= flash_ioctl,
  };
  
  static struct miscdevice flash_miscdev =
  {
  	FLASH_MINOR,
  	"nwflash",
  	&flash_fops
  };
  
  static int __init nwflash_init(void)
  {
  	int ret = -ENODEV;
  
  	if (machine_is_netwinder()) {
  		int id;
  
  		FLASH_BASE = ioremap(DC21285_FLASH, KFLASH_SIZE4);
  		if (!FLASH_BASE)
  			goto out;
  
  		id = get_flash_id();
  		if ((id != KFLASH_ID) && (id != KFLASH_ID4)) {
  			ret = -ENXIO;
  			iounmap((void *)FLASH_BASE);
  			printk("Flash: incorrect ID 0x%04X.
  ", id);
  			goto out;
  		}
  
  		printk("Flash ROM driver v.%s, flash device ID 0x%04X, size %d Mb.
  ",
  		       NWFLASH_VERSION, id, gbFlashSize / (1024 * 1024));
  
  		ret = misc_register(&flash_miscdev);
  		if (ret < 0) {
  			iounmap((void *)FLASH_BASE);
  		}
  	}
  out:
  	return ret;
  }
  
  static void __exit nwflash_exit(void)
  {
  	misc_deregister(&flash_miscdev);
  	iounmap((void *)FLASH_BASE);
  }
  
  MODULE_LICENSE("GPL");
  
  module_param(flashdebug, bool, 0644);
  
  module_init(nwflash_init);
  module_exit(nwflash_exit);