text: /*
   * Driver for IBM Power 842 compression accelerator
   *
   * 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, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
   *
   * Copyright (C) IBM Corporation, 2012
   *
   * Authors: Robert Jennings <rcj@linux.vnet.ibm.com>
   *          Seth Jennings <sjenning@linux.vnet.ibm.com>
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/nx842.h>
  #include <linux/of.h>
  #include <linux/slab.h>
  
  #include <asm/page.h>
  #include <asm/vio.h>
  
  #include "nx_csbcpb.h" /* struct nx_csbcpb */
  
  #define MODULE_NAME "nx-compress"
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Robert Jennings <rcj@linux.vnet.ibm.com>");
  MODULE_DESCRIPTION("842 H/W Compression driver for IBM Power processors");
  
  #define SHIFT_4K 12
  #define SHIFT_64K 16
  #define SIZE_4K (1UL << SHIFT_4K)
  #define SIZE_64K (1UL << SHIFT_64K)
  
  /* IO buffer must be 128 byte aligned */
  #define IO_BUFFER_ALIGN 128
  
  struct nx842_header {
  	int blocks_nr; /* number of compressed blocks */
  	int offset; /* offset of the first block (from beginning of header) */
  	int sizes[0]; /* size of compressed blocks */
  };
  
  static inline int nx842_header_size(const struct nx842_header *hdr)
  {
  	return sizeof(struct nx842_header) +
  			hdr->blocks_nr * sizeof(hdr->sizes[0]);
  }
  
  /* Macros for fields within nx_csbcpb */
  /* Check the valid bit within the csbcpb valid field */
  #define NX842_CSBCBP_VALID_CHK(x) (x & BIT_MASK(7))
  
  /* CE macros operate on the completion_extension field bits in the csbcpb.
   * CE0 0=full completion, 1=partial completion
   * CE1 0=CE0 indicates completion, 1=termination (output may be modified)
   * CE2 0=processed_bytes is source bytes, 1=processed_bytes is target bytes */
  #define NX842_CSBCPB_CE0(x)	(x & BIT_MASK(7))
  #define NX842_CSBCPB_CE1(x)	(x & BIT_MASK(6))
  #define NX842_CSBCPB_CE2(x)	(x & BIT_MASK(5))
  
  /* The NX unit accepts data only on 4K page boundaries */
  #define NX842_HW_PAGE_SHIFT	SHIFT_4K
  #define NX842_HW_PAGE_SIZE	(ASM_CONST(1) << NX842_HW_PAGE_SHIFT)
  #define NX842_HW_PAGE_MASK	(~(NX842_HW_PAGE_SIZE-1))
  
  enum nx842_status {
  	UNAVAILABLE,
  	AVAILABLE
  };
  
  struct ibm_nx842_counters {
  	atomic64_t comp_complete;
  	atomic64_t comp_failed;
  	atomic64_t decomp_complete;
  	atomic64_t decomp_failed;
  	atomic64_t swdecomp;
  	atomic64_t comp_times[32];
  	atomic64_t decomp_times[32];
  };
  
  static struct nx842_devdata {
  	struct vio_dev *vdev;
  	struct device *dev;
  	struct ibm_nx842_counters *counters;
  	unsigned int max_sg_len;
  	unsigned int max_sync_size;
  	unsigned int max_sync_sg;
  	enum nx842_status status;
  } __rcu *devdata;
  static DEFINE_SPINLOCK(devdata_mutex);
  
  #define NX842_COUNTER_INC(_x) \
  static inline void nx842_inc_##_x( \
  	const struct nx842_devdata *dev) { \
  	if (dev) \
  		atomic64_inc(&dev->counters->_x); \
  }
  NX842_COUNTER_INC(comp_complete);
  NX842_COUNTER_INC(comp_failed);
  NX842_COUNTER_INC(decomp_complete);
  NX842_COUNTER_INC(decomp_failed);
  NX842_COUNTER_INC(swdecomp);
  
  #define NX842_HIST_SLOTS 16
  
  static void ibm_nx842_incr_hist(atomic64_t *times, unsigned int time)
  {
  	int bucket = fls(time);
  
  	if (bucket)
  		bucket = min((NX842_HIST_SLOTS - 1), bucket - 1);
  
  	atomic64_inc(&times[bucket]);
  }
  
  /* NX unit operation flags */
  #define NX842_OP_COMPRESS	0x0
  #define NX842_OP_CRC		0x1
  #define NX842_OP_DECOMPRESS	0x2
  #define NX842_OP_COMPRESS_CRC   (NX842_OP_COMPRESS | NX842_OP_CRC)
  #define NX842_OP_DECOMPRESS_CRC (NX842_OP_DECOMPRESS | NX842_OP_CRC)
  #define NX842_OP_ASYNC		(1<<23)
  #define NX842_OP_NOTIFY		(1<<22)
  #define NX842_OP_NOTIFY_INT(x)	((x & 0xff)<<8)
  
  static unsigned long nx842_get_desired_dma(struct vio_dev *viodev)
  {
  	/* No use of DMA mappings within the driver. */
  	return 0;
  }
  
  struct nx842_slentry {
  	unsigned long ptr; /* Real address (use __pa()) */
  	unsigned long len;
  };
  
  /* pHyp scatterlist entry */
  struct nx842_scatterlist {
  	int entry_nr; /* number of slentries */
  	struct nx842_slentry *entries; /* ptr to array of slentries */
  };
  
  /* Does not include sizeof(entry_nr) in the size */
  static inline unsigned long nx842_get_scatterlist_size(
  				struct nx842_scatterlist *sl)
  {
  	return sl->entry_nr * sizeof(struct nx842_slentry);
  }
  
  static inline unsigned long nx842_get_pa(void *addr)
  {
  	if (is_vmalloc_addr(addr))
  		return page_to_phys(vmalloc_to_page(addr))
  		       + offset_in_page(addr);
  	else
  		return __pa(addr);
  }
  
  static int nx842_build_scatterlist(unsigned long buf, int len,
  			struct nx842_scatterlist *sl)
  {
  	unsigned long nextpage;
  	struct nx842_slentry *entry;
  
  	sl->entry_nr = 0;
  
  	entry = sl->entries;
  	while (len) {
  		entry->ptr = nx842_get_pa((void *)buf);
  		nextpage = ALIGN(buf + 1, NX842_HW_PAGE_SIZE);
  		if (nextpage < buf + len) {
  			/* we aren't at the end yet */
  			if (IS_ALIGNED(buf, NX842_HW_PAGE_SIZE))
  				/* we are in the middle (or beginning) */
  				entry->len = NX842_HW_PAGE_SIZE;
  			else
  				/* we are at the beginning */
  				entry->len = nextpage - buf;
  		} else {
  			/* at the end */
  			entry->len = len;
  		}
  
  		len -= entry->len;
  		buf += entry->len;
  		sl->entry_nr++;
  		entry++;
  	}
  
  	return 0;
  }
  
  /*
   * Working memory for software decompression
   */
  struct sw842_fifo {
  	union {
  		char f8[256][8];
  		char f4[512][4];
  	};
  	char f2[256][2];
  	unsigned char f84_full;
  	unsigned char f2_full;
  	unsigned char f8_count;
  	unsigned char f2_count;
  	unsigned int f4_count;
  };
  
  /*
   * Working memory for crypto API
   */
  struct nx842_workmem {
  	char bounce[PAGE_SIZE]; /* bounce buffer for decompression input */
  	union {
  		/* hardware working memory */
  		struct {
  			/* scatterlist */
  			char slin[SIZE_4K];
  			char slout[SIZE_4K];
  			/* coprocessor status/parameter block */
  			struct nx_csbcpb csbcpb;
  		};
  		/* software working memory */
  		struct sw842_fifo swfifo; /* software decompression fifo */
  	};
  };
  
  int nx842_get_workmem_size(void)
  {
  	return sizeof(struct nx842_workmem) + NX842_HW_PAGE_SIZE;
  }
  EXPORT_SYMBOL_GPL(nx842_get_workmem_size);
  
  int nx842_get_workmem_size_aligned(void)
  {
  	return sizeof(struct nx842_workmem);
  }
  EXPORT_SYMBOL_GPL(nx842_get_workmem_size_aligned);
  
  static int nx842_validate_result(struct device *dev,
  	struct cop_status_block *csb)
  {
  	/* The csb must be valid after returning from vio_h_cop_sync */
  	if (!NX842_CSBCBP_VALID_CHK(csb->valid)) {
  		dev_err(dev, "%s: cspcbp not valid upon completion.\n",
  				__func__);
  		dev_dbg(dev, "valid:0x%02x cs:0x%02x cc:0x%02x ce:0x%02x\n",
  				csb->valid,
  				csb->crb_seq_number,
  				csb->completion_code,
  				csb->completion_extension);
  		dev_dbg(dev, "processed_bytes:%d address:0x%016lx\n",
  				csb->processed_byte_count,
  				(unsigned long)csb->address);
  		return -EIO;
  	}
  
  	/* Check return values from the hardware in the CSB */
  	switch (csb->completion_code) {
  	case 0:	/* Completed without error */
  		break;
  	case 64: /* Target bytes > Source bytes during compression */
  	case 13: /* Output buffer too small */
  		dev_dbg(dev, "%s: Compression output larger than input\n",
  					__func__);
  		return -ENOSPC;
  	case 66: /* Input data contains an illegal template field */
  	case 67: /* Template indicates data past the end of the input stream */
  		dev_dbg(dev, "%s: Bad data for decompression (code:%d)\n",
  					__func__, csb->completion_code);
  		return -EINVAL;
  	default:
  		dev_dbg(dev, "%s: Unspecified error (code:%d)\n",
  					__func__, csb->completion_code);
  		return -EIO;
  	}
  
  	/* Hardware sanity check */
  	if (!NX842_CSBCPB_CE2(csb->completion_extension)) {
  		dev_err(dev, "%s: No error returned by hardware, but "
  				"data returned is unusable, contact support.\n"
  				"(Additional info: csbcbp->processed bytes "
  				"does not specify processed bytes for the "
  				"target buffer.)\n", __func__);
  		return -EIO;
  	}
  
  	return 0;
  }
  
  /**
   * nx842_compress - Compress data using the 842 algorithm
   *
   * Compression provide by the NX842 coprocessor on IBM Power systems.
   * The input buffer is compressed and the result is stored in the
   * provided output buffer.
   *
   * Upon return from this function @outlen contains the length of the
   * compressed data.  If there is an error then @outlen will be 0 and an
   * error will be specified by the return code from this function.
   *
   * @in: Pointer to input buffer, must be page aligned
   * @inlen: Length of input buffer, must be PAGE_SIZE
   * @out: Pointer to output buffer
   * @outlen: Length of output buffer
   * @wrkmem: ptr to buffer for working memory, size determined by
   *          nx842_get_workmem_size()
   *
   * Returns:
   *   0		Success, output of length @outlen stored in the buffer at @out
   *   -ENOMEM	Unable to allocate internal buffers
   *   -ENOSPC	Output buffer is to small
   *   -EMSGSIZE	XXX Difficult to describe this limitation
   *   -EIO	Internal error
   *   -ENODEV	Hardware unavailable
   */
  int nx842_compress(const unsigned char *in, unsigned int inlen,
  		       unsigned char *out, unsigned int *outlen, void *wmem)
  {
  	struct nx842_header *hdr;
  	struct nx842_devdata *local_devdata;
  	struct device *dev = NULL;
  	struct nx842_workmem *workmem;
  	struct nx842_scatterlist slin, slout;
  	struct nx_csbcpb *csbcpb;
  	int ret = 0, max_sync_size, i, bytesleft, size, hdrsize;
  	unsigned long inbuf, outbuf, padding;
  	struct vio_pfo_op op = {
  		.done = NULL,
  		.handle = 0,
  		.timeout = 0,
  	};
  	unsigned long start_time = get_tb();
  
  	/*
  	 * Make sure input buffer is 64k page aligned.  This is assumed since
  	 * this driver is designed for page compression only (for now).  This
  	 * is very nice since we can now use direct DDE(s) for the input and
  	 * the alignment is guaranteed.
  	*/
  	inbuf = (unsigned long)in;
  	if (!IS_ALIGNED(inbuf, PAGE_SIZE) || inlen != PAGE_SIZE)
  		return -EINVAL;
  
  	rcu_read_lock();
  	local_devdata = rcu_dereference(devdata);
  	if (!local_devdata || !local_devdata->dev) {
  		rcu_read_unlock();
  		return -ENODEV;
  	}
  	max_sync_size = local_devdata->max_sync_size;
  	dev = local_devdata->dev;
  
  	/* Create the header */
  	hdr = (struct nx842_header *)out;
  	hdr->blocks_nr = PAGE_SIZE / max_sync_size;
  	hdrsize = nx842_header_size(hdr);
  	outbuf = (unsigned long)out + hdrsize;
  	bytesleft = *outlen - hdrsize;
  
  	/* Init scatterlist */
  	workmem = (struct nx842_workmem *)ALIGN((unsigned long)wmem,
  		NX842_HW_PAGE_SIZE);
  	slin.entries = (struct nx842_slentry *)workmem->slin;
  	slout.entries = (struct nx842_slentry *)workmem->slout;
  
  	/* Init operation */
  	op.flags = NX842_OP_COMPRESS;
  	csbcpb = &workmem->csbcpb;
  	memset(csbcpb, 0, sizeof(*csbcpb));
  	op.csbcpb = nx842_get_pa(csbcpb);
  	op.out = nx842_get_pa(slout.entries);
  
  	for (i = 0; i < hdr->blocks_nr; i++) {
  		/*
  		 * Aligning the output blocks to 128 bytes does waste space,
  		 * but it prevents the need for bounce buffers and memory
  		 * copies.  It also simplifies the code a lot.  In the worst
  		 * case (64k page, 4k max_sync_size), you lose up to
  		 * (128*16)/64k = ~3% the compression factor. For 64k
  		 * max_sync_size, the loss would be at most 128/64k = ~0.2%.
  		 */
  		padding = ALIGN(outbuf, IO_BUFFER_ALIGN) - outbuf;
  		outbuf += padding;
  		bytesleft -= padding;
  		if (i == 0)
  			/* save offset into first block in header */
  			hdr->offset = padding + hdrsize;
  
  		if (bytesleft <= 0) {
  			ret = -ENOSPC;
  			goto unlock;
  		}
  
  		/*
  		 * NOTE: If the default max_sync_size is changed from 4k
  		 * to 64k, remove the "likely" case below, since a
  		 * scatterlist will always be needed.
  		 */
  		if (likely(max_sync_size == NX842_HW_PAGE_SIZE)) {
  			/* Create direct DDE */
  			op.in = nx842_get_pa((void *)inbuf);
  			op.inlen = max_sync_size;
  
  		} else {
  			/* Create indirect DDE (scatterlist) */
  			nx842_build_scatterlist(inbuf, max_sync_size, &slin);
  			op.in = nx842_get_pa(slin.entries);
  			op.inlen = -nx842_get_scatterlist_size(&slin);
  		}
  
  		/*
  		 * If max_sync_size != NX842_HW_PAGE_SIZE, an indirect
  		 * DDE is required for the outbuf.
  		 * If max_sync_size == NX842_HW_PAGE_SIZE, outbuf must
  		 * also be page aligned (1 in 128/4k=32 chance) in order
  		 * to use a direct DDE.
  		 * This is unlikely, just use an indirect DDE always.
  		 */
  		nx842_build_scatterlist(outbuf,
  			min(bytesleft, max_sync_size), &slout);
  		/* op.out set before loop */
  		op.outlen = -nx842_get_scatterlist_size(&slout);
  
  		/* Send request to pHyp */
  		ret = vio_h_cop_sync(local_devdata->vdev, &op);
  
  		/* Check for pHyp error */
  		if (ret) {
  			dev_dbg(dev, "%s: vio_h_cop_sync error (ret=%d, hret=%ld)\n",
  				__func__, ret, op.hcall_err);
  			ret = -EIO;
  			goto unlock;
  		}
  
  		/* Check for hardware error */
  		ret = nx842_validate_result(dev, &csbcpb->csb);
  		if (ret && ret != -ENOSPC)
  			goto unlock;
  
  		/* Handle incompressible data */
  		if (unlikely(ret == -ENOSPC)) {
  			if (bytesleft < max_sync_size) {
  				/*
  				 * Not enough space left in the output buffer
  				 * to store uncompressed block
  				 */
  				goto unlock;
  			} else {
  				/* Store incompressible block */
  				memcpy((void *)outbuf, (void *)inbuf,
  					max_sync_size);
  				hdr->sizes[i] = -max_sync_size;
  				outbuf += max_sync_size;
  				bytesleft -= max_sync_size;
  				/* Reset ret, incompressible data handled */
  				ret = 0;
  			}
  		} else {
  			/* Normal case, compression was successful */
  			size = csbcpb->csb.processed_byte_count;
  			dev_dbg(dev, "%s: processed_bytes=%d\n",
  				__func__, size);
  			hdr->sizes[i] = size;
  			outbuf += size;
  			bytesleft -= size;
  		}
  
  		inbuf += max_sync_size;
  	}
  
  	*outlen = (unsigned int)(outbuf - (unsigned long)out);
  
  unlock:
  	if (ret)
  		nx842_inc_comp_failed(local_devdata);
  	else {
  		nx842_inc_comp_complete(local_devdata);
  		ibm_nx842_incr_hist(local_devdata->counters->comp_times,
  			(get_tb() - start_time) / tb_ticks_per_usec);
  	}
  	rcu_read_unlock();
  	return ret;
  }
  EXPORT_SYMBOL_GPL(nx842_compress);
  
  static int sw842_decompress(const unsigned char *, int, unsigned char *, int *,
  			const void *);
  
  /**
   * nx842_decompress - Decompress data using the 842 algorithm
   *
   * Decompression provide by the NX842 coprocessor on IBM Power systems.
   * The input buffer is decompressed and the result is stored in the
   * provided output buffer.  The size allocated to the output buffer is
   * provided by the caller of this function in @outlen.  Upon return from
   * this function @outlen contains the length of the decompressed data.
   * If there is an error then @outlen will be 0 and an error will be
   * specified by the return code from this function.
   *
   * @in: Pointer to input buffer, will use bounce buffer if not 128 byte
   *      aligned
   * @inlen: Length of input buffer
   * @out: Pointer to output buffer, must be page aligned
   * @outlen: Length of output buffer, must be PAGE_SIZE
   * @wrkmem: ptr to buffer for working memory, size determined by
   *          nx842_get_workmem_size()
   *
   * Returns:
   *   0		Success, output of length @outlen stored in the buffer at @out
   *   -ENODEV	Hardware decompression device is unavailable
   *   -ENOMEM	Unable to allocate internal buffers
   *   -ENOSPC	Output buffer is to small
   *   -EINVAL	Bad input data encountered when attempting decompress
   *   -EIO	Internal error
   */
  int nx842_decompress(const unsigned char *in, unsigned int inlen,
  			 unsigned char *out, unsigned int *outlen, void *wmem)
  {
  	struct nx842_header *hdr;
  	struct nx842_devdata *local_devdata;
  	struct device *dev = NULL;
  	struct nx842_workmem *workmem;
  	struct nx842_scatterlist slin, slout;
  	struct nx_csbcpb *csbcpb;
  	int ret = 0, i, size, max_sync_size;
  	unsigned long inbuf, outbuf;
  	struct vio_pfo_op op = {
  		.done = NULL,
  		.handle = 0,
  		.timeout = 0,
  	};
  	unsigned long start_time = get_tb();
  
  	/* Ensure page alignment and size */
  	outbuf = (unsigned long)out;
  	if (!IS_ALIGNED(outbuf, PAGE_SIZE) || *outlen != PAGE_SIZE)
  		return -EINVAL;
  
  	rcu_read_lock();
  	local_devdata = rcu_dereference(devdata);
  	if (local_devdata)
  		dev = local_devdata->dev;
  
  	/* Get header */
  	hdr = (struct nx842_header *)in;
  
  	workmem = (struct nx842_workmem *)ALIGN((unsigned long)wmem,
  		NX842_HW_PAGE_SIZE);
  
  	inbuf = (unsigned long)in + hdr->offset;
  	if (likely(!IS_ALIGNED(inbuf, IO_BUFFER_ALIGN))) {
  		/* Copy block(s) into bounce buffer for alignment */
  		memcpy(workmem->bounce, in + hdr->offset, inlen - hdr->offset);
  		inbuf = (unsigned long)workmem->bounce;
  	}
  
  	/* Init scatterlist */
  	slin.entries = (struct nx842_slentry *)workmem->slin;
  	slout.entries = (struct nx842_slentry *)workmem->slout;
  
  	/* Init operation */
  	op.flags = NX842_OP_DECOMPRESS;
  	csbcpb = &workmem->csbcpb;
  	memset(csbcpb, 0, sizeof(*csbcpb));
  	op.csbcpb = nx842_get_pa(csbcpb);
  
  	/*
  	 * max_sync_size may have changed since compression,
  	 * so we can't read it from the device info. We need
  	 * to derive it from hdr->blocks_nr.
  	 */
  	max_sync_size = PAGE_SIZE / hdr->blocks_nr;
  
  	for (i = 0; i < hdr->blocks_nr; i++) {
  		/* Skip padding */
  		inbuf = ALIGN(inbuf, IO_BUFFER_ALIGN);
  
  		if (hdr->sizes[i] < 0) {
  			/* Negative sizes indicate uncompressed data blocks */
  			size = abs(hdr->sizes[i]);
  			memcpy((void *)outbuf, (void *)inbuf, size);
  			outbuf += size;
  			inbuf += size;
  			continue;
  		}
  
  		if (!dev)
  			goto sw;
  
  		/*
  		 * The better the compression, the more likely the "likely"
  		 * case becomes.
  		 */
  		if (likely((inbuf & NX842_HW_PAGE_MASK) ==
  			((inbuf + hdr->sizes[i] - 1) & NX842_HW_PAGE_MASK))) {
  			/* Create direct DDE */
  			op.in = nx842_get_pa((void *)inbuf);
  			op.inlen = hdr->sizes[i];
  		} else {
  			/* Create indirect DDE (scatterlist) */
  			nx842_build_scatterlist(inbuf, hdr->sizes[i] , &slin);
  			op.in = nx842_get_pa(slin.entries);
  			op.inlen = -nx842_get_scatterlist_size(&slin);
  		}
  
  		/*
  		 * NOTE: If the default max_sync_size is changed from 4k
  		 * to 64k, remove the "likely" case below, since a
  		 * scatterlist will always be needed.
  		 */
  		if (likely(max_sync_size == NX842_HW_PAGE_SIZE)) {
  			/* Create direct DDE */
  			op.out = nx842_get_pa((void *)outbuf);
  			op.outlen = max_sync_size;
  		} else {
  			/* Create indirect DDE (scatterlist) */
  			nx842_build_scatterlist(outbuf, max_sync_size, &slout);
  			op.out = nx842_get_pa(slout.entries);
  			op.outlen = -nx842_get_scatterlist_size(&slout);
  		}
  
  		/* Send request to pHyp */
  		ret = vio_h_cop_sync(local_devdata->vdev, &op);
  
  		/* Check for pHyp error */
  		if (ret) {
  			dev_dbg(dev, "%s: vio_h_cop_sync error (ret=%d, hret=%ld)\n",
  				__func__, ret, op.hcall_err);
  			dev = NULL;
  			goto sw;
  		}
  
  		/* Check for hardware error */
  		ret = nx842_validate_result(dev, &csbcpb->csb);
  		if (ret) {
  			dev = NULL;
  			goto sw;
  		}
  
  		/* HW decompression success */
  		inbuf += hdr->sizes[i];
  		outbuf += csbcpb->csb.processed_byte_count;
  		continue;
  
  sw:
  		/* software decompression */
  		size = max_sync_size;
  		ret = sw842_decompress(
  			(unsigned char *)inbuf, hdr->sizes[i],
  			(unsigned char *)outbuf, &size, wmem);
  		if (ret)
  			pr_debug("%s: sw842_decompress failed with %d\n",
  				__func__, ret);
  
  		if (ret) {
  			if (ret != -ENOSPC && ret != -EINVAL &&
  					ret != -EMSGSIZE)
  				ret = -EIO;
  			goto unlock;
  		}
  
  		/* SW decompression success */
  		inbuf += hdr->sizes[i];
  		outbuf += size;
  	}
  
  	*outlen = (unsigned int)(outbuf - (unsigned long)out);
  
  unlock:
  	if (ret)
  		/* decompress fail */
  		nx842_inc_decomp_failed(local_devdata);
  	else {
  		if (!dev)
  			/* software decompress */
  			nx842_inc_swdecomp(local_devdata);
  		nx842_inc_decomp_complete(local_devdata);
  		ibm_nx842_incr_hist(local_devdata->counters->decomp_times,
  			(get_tb() - start_time) / tb_ticks_per_usec);
  	}
  
  	rcu_read_unlock();
  	return ret;
  }
  EXPORT_SYMBOL_GPL(nx842_decompress);
  
  /**
   * nx842_OF_set_defaults -- Set default (disabled) values for devdata
   *
   * @devdata - struct nx842_devdata to update
   *
   * Returns:
   *  0 on success
   *  -ENOENT if @devdata ptr is NULL
   */
  static int nx842_OF_set_defaults(struct nx842_devdata *devdata)
  {
  	if (devdata) {
  		devdata->max_sync_size = 0;
  		devdata->max_sync_sg = 0;
  		devdata->max_sg_len = 0;
  		devdata->status = UNAVAILABLE;
  		return 0;
  	} else
  		return -ENOENT;
  }
  
  /**
   * nx842_OF_upd_status -- Update the device info from OF status prop
   *
   * The status property indicates if the accelerator is enabled.  If the
   * device is in the OF tree it indicates that the hardware is present.
   * The status field indicates if the device is enabled when the status
   * is 'okay'.  Otherwise the device driver will be disabled.
   *
   * @devdata - struct nx842_devdata to update
   * @prop - struct property point containing the maxsyncop for the update
   *
   * Returns:
   *  0 - Device is available
   *  -EINVAL - Device is not available
   */
  static int nx842_OF_upd_status(struct nx842_devdata *devdata,
  					struct property *prop) {
  	int ret = 0;
  	const char *status = (const char *)prop->value;
  
  	if (!strncmp(status, "okay", (size_t)prop->length)) {
  		devdata->status = AVAILABLE;
  	} else {
  		dev_info(devdata->dev, "%s: status '%s' is not 'okay'\n",
  				__func__, status);
  		devdata->status = UNAVAILABLE;
  	}
  
  	return ret;
  }
  
  /**
   * nx842_OF_upd_maxsglen -- Update the device info from OF maxsglen prop
   *
   * Definition of the 'ibm,max-sg-len' OF property:
   *  This field indicates the maximum byte length of a scatter list
   *  for the platform facility. It is a single cell encoded as with encode-int.
   *
   * Example:
   *  # od -x ibm,max-sg-len
   *  0000000 0000 0ff0
   *
   *  In this example, the maximum byte length of a scatter list is
   *  0x0ff0 (4,080).
   *
   * @devdata - struct nx842_devdata to update
   * @prop - struct property point containing the maxsyncop for the update
   *
   * Returns:
   *  0 on success
   *  -EINVAL on failure
   */
  static int nx842_OF_upd_maxsglen(struct nx842_devdata *devdata,
  					struct property *prop) {
  	int ret = 0;
  	const int *maxsglen = prop->value;
  
  	if (prop->length != sizeof(*maxsglen)) {
  		dev_err(devdata->dev, "%s: unexpected format for ibm,max-sg-len property\n", __func__);
  		dev_dbg(devdata->dev, "%s: ibm,max-sg-len is %d bytes long, expected %lu bytes\n", __func__,
  				prop->length, sizeof(*maxsglen));
  		ret = -EINVAL;
  	} else {
  		devdata->max_sg_len = (unsigned int)min(*maxsglen,
  				(int)NX842_HW_PAGE_SIZE);
  	}
  
  	return ret;
  }
  
  /**
   * nx842_OF_upd_maxsyncop -- Update the device info from OF maxsyncop prop
   *
   * Definition of the 'ibm,max-sync-cop' OF property:
   *  Two series of cells.  The first series of cells represents the maximums
   *  that can be synchronously compressed. The second series of cells
   *  represents the maximums that can be synchronously decompressed.
   *  1. The first cell in each series contains the count of the number of
   *     data length, scatter list elements pairs that follow – each being
   *     of the form
   *    a. One cell data byte length
   *    b. One cell total number of scatter list elements
   *
   * Example:
   *  # od -x ibm,max-sync-cop
   *  0000000 0000 0001 0000 1000 0000 01fe 0000 0001
   *  0000020 0000 1000 0000 01fe
   *
   *  In this example, compression supports 0x1000 (4,096) data byte length
   *  and 0x1fe (510) total scatter list elements.  Decompression supports
   *  0x1000 (4,096) data byte length and 0x1f3 (510) total scatter list
   *  elements.
   *
   * @devdata - struct nx842_devdata to update
   * @prop - struct property point containing the maxsyncop for the update
   *
   * Returns:
   *  0 on success
   *  -EINVAL on failure
   */
  static int nx842_OF_upd_maxsyncop(struct nx842_devdata *devdata,
  					struct property *prop) {
  	int ret = 0;
  	const struct maxsynccop_t {
  		int comp_elements;
  		int comp_data_limit;
  		int comp_sg_limit;
  		int decomp_elements;
  		int decomp_data_limit;
  		int decomp_sg_limit;
  	} *maxsynccop;
  
  	if (prop->length != sizeof(*maxsynccop)) {
  		dev_err(devdata->dev, "%s: unexpected format for ibm,max-sync-cop property\n", __func__);
  		dev_dbg(devdata->dev, "%s: ibm,max-sync-cop is %d bytes long, expected %lu bytes\n", __func__, prop->length,
  				sizeof(*maxsynccop));
  		ret = -EINVAL;
  		goto out;
  	}
  
  	maxsynccop = (const struct maxsynccop_t *)prop->value;
  
  	/* Use one limit rather than separate limits for compression and
  	 * decompression. Set a maximum for this so as not to exceed the
  	 * size that the header can support and round the value down to
  	 * the hardware page size (4K) */
  	devdata->max_sync_size =
  			(unsigned int)min(maxsynccop->comp_data_limit,
  					maxsynccop->decomp_data_limit);
  
  	devdata->max_sync_size = min_t(unsigned int, devdata->max_sync_size,
  					SIZE_64K);
  
  	if (devdata->max_sync_size < SIZE_4K) {
  		dev_err(devdata->dev, "%s: hardware max data size (%u) is "
  				"less than the driver minimum, unable to use "
  				"the hardware device\n",
  				__func__, devdata->max_sync_size);
  		ret = -EINVAL;
  		goto out;
  	}
  
  	devdata->max_sync_sg = (unsigned int)min(maxsynccop->comp_sg_limit,
  						maxsynccop->decomp_sg_limit);
  	if (devdata->max_sync_sg < 1) {
  		dev_err(devdata->dev, "%s: hardware max sg size (%u) is "
  				"less than the driver minimum, unable to use "
  				"the hardware device\n",
  				__func__, devdata->max_sync_sg);
  		ret = -EINVAL;
  		goto out;
  	}
  
  out:
  	return ret;
  }
  
  /**
   *
   * nx842_OF_upd -- Handle OF properties updates for the device.
   *
   * Set all properties from the OF tree.  Optionally, a new property
   * can be provided by the @new_prop pointer to overwrite an existing value.
   * The device will remain disabled until all values are valid, this function
   * will return an error for updates unless all values are valid.
   *
   * @new_prop: If not NULL, this property is being updated.  If NULL, update
   *  all properties from the current values in the OF tree.
   *
   * Returns:
   *  0 - Success
   *  -ENOMEM - Could not allocate memory for new devdata structure
   *  -EINVAL - property value not found, new_prop is not a recognized
   *	property for the device or property value is not valid.
   *  -ENODEV - Device is not available
   */
  static int nx842_OF_upd(struct property *new_prop)
  {
  	struct nx842_devdata *old_devdata = NULL;
  	struct nx842_devdata *new_devdata = NULL;
  	struct device_node *of_node = NULL;
  	struct property *status = NULL;
  	struct property *maxsglen = NULL;
  	struct property *maxsyncop = NULL;
  	int ret = 0;
  	unsigned long flags;
  
  	spin_lock_irqsave(&devdata_mutex, flags);
  	old_devdata = rcu_dereference_check(devdata,
  			lockdep_is_held(&devdata_mutex));
  	if (old_devdata)
  		of_node = old_devdata->dev->of_node;
  
  	if (!old_devdata || !of_node) {
  		pr_err("%s: device is not available\n", __func__);
  		spin_unlock_irqrestore(&devdata_mutex, flags);
  		return -ENODEV;
  	}
  
  	new_devdata = kzalloc(sizeof(*new_devdata), GFP_NOFS);
  	if (!new_devdata) {
  		dev_err(old_devdata->dev, "%s: Could not allocate memory for device data\n", __func__);
  		ret = -ENOMEM;
  		goto error_out;
  	}
  
  	memcpy(new_devdata, old_devdata, sizeof(*old_devdata));
  	new_devdata->counters = old_devdata->counters;
  
  	/* Set ptrs for existing properties */
  	status = of_find_property(of_node, "status", NULL);
  	maxsglen = of_find_property(of_node, "ibm,max-sg-len", NULL);
  	maxsyncop = of_find_property(of_node, "ibm,max-sync-cop", NULL);
  	if (!status || !maxsglen || !maxsyncop) {
  		dev_err(old_devdata->dev, "%s: Could not locate device properties\n", __func__);
  		ret = -EINVAL;
  		goto error_out;
  	}
  
  	/*
  	 * If this is a property update, there are only certain properties that
  	 * we care about. Bail if it isn't in the below list
  	 */
  	if (new_prop && (strncmp(new_prop->name, "status", new_prop->length) ||
  		         strncmp(new_prop->name, "ibm,max-sg-len", new_prop->length) ||
  		         strncmp(new_prop->name, "ibm,max-sync-cop", new_prop->length)))
  		goto out;
  
  	/* Perform property updates */
  	ret = nx842_OF_upd_status(new_devdata, status);
  	if (ret)
  		goto error_out;
  
  	ret = nx842_OF_upd_maxsglen(new_devdata, maxsglen);
  	if (ret)
  		goto error_out;
  
  	ret = nx842_OF_upd_maxsyncop(new_devdata, maxsyncop);
  	if (ret)
  		goto error_out;
  
  out:
  	dev_info(old_devdata->dev, "%s: max_sync_size new:%u old:%u\n",
  			__func__, new_devdata->max_sync_size,
  			old_devdata->max_sync_size);
  	dev_info(old_devdata->dev, "%s: max_sync_sg new:%u old:%u\n",
  			__func__, new_devdata->max_sync_sg,
  			old_devdata->max_sync_sg);
  	dev_info(old_devdata->dev, "%s: max_sg_len new:%u old:%u\n",
  			__func__, new_devdata->max_sg_len,
  			old_devdata->max_sg_len);
  
  	rcu_assign_pointer(devdata, new_devdata);
  	spin_unlock_irqrestore(&devdata_mutex, flags);
  	synchronize_rcu();
  	dev_set_drvdata(new_devdata->dev, new_devdata);
  	kfree(old_devdata);
  	return 0;
  
  error_out:
  	if (new_devdata) {
  		dev_info(old_devdata->dev, "%s: device disabled\n", __func__);
  		nx842_OF_set_defaults(new_devdata);
  		rcu_assign_pointer(devdata, new_devdata);
  		spin_unlock_irqrestore(&devdata_mutex, flags);
  		synchronize_rcu();
  		dev_set_drvdata(new_devdata->dev, new_devdata);
  		kfree(old_devdata);
  	} else {
  		dev_err(old_devdata->dev, "%s: could not update driver from hardware\n", __func__);
  		spin_unlock_irqrestore(&devdata_mutex, flags);
  	}
  
  	if (!ret)
  		ret = -EINVAL;
  	return ret;
  }
  
  /**
   * nx842_OF_notifier - Process updates to OF properties for the device
   *
   * @np: notifier block
   * @action: notifier action
   * @update: struct pSeries_reconfig_prop_update pointer if action is
   *	PSERIES_UPDATE_PROPERTY
   *
   * Returns:
   *	NOTIFY_OK on success
   *	NOTIFY_BAD encoded with error number on failure, use
   *		notifier_to_errno() to decode this value
   */
  static int nx842_OF_notifier(struct notifier_block *np, unsigned long action,
  			     void *update)
  {
  	struct of_prop_reconfig *upd = update;
  	struct nx842_devdata *local_devdata;
  	struct device_node *node = NULL;
  
  	rcu_read_lock();
  	local_devdata = rcu_dereference(devdata);
  	if (local_devdata)
  		node = local_devdata->dev->of_node;
  
  	if (local_devdata &&
  			action == OF_RECONFIG_UPDATE_PROPERTY &&
  			!strcmp(upd->dn->name, node->name)) {
  		rcu_read_unlock();
  		nx842_OF_upd(upd->prop);
  	} else
  		rcu_read_unlock();
  
  	return NOTIFY_OK;
  }
  
  static struct notifier_block nx842_of_nb = {
  	.notifier_call = nx842_OF_notifier,
  };
  
  #define nx842_counter_read(_name)					\
  static ssize_t nx842_##_name##_show(struct device *dev,		\
  		struct device_attribute *attr,				\
  		char *buf) {						\
  	struct nx842_devdata *local_devdata;			\
  	int p = 0;							\
  	rcu_read_lock();						\
  	local_devdata = rcu_dereference(devdata);			\
  	if (local_devdata)						\
  		p = snprintf(buf, PAGE_SIZE, "%ld\n",			\
  		       atomic64_read(&local_devdata->counters->_name));	\
  	rcu_read_unlock();						\
  	return p;							\
  }
  
  #define NX842DEV_COUNTER_ATTR_RO(_name)					\
  	nx842_counter_read(_name);					\
  	static struct device_attribute dev_attr_##_name = __ATTR(_name,	\
  						0444,			\
  						nx842_##_name##_show,\
  						NULL);
  
  NX842DEV_COUNTER_ATTR_RO(comp_complete);
  NX842DEV_COUNTER_ATTR_RO(comp_failed);
  NX842DEV_COUNTER_ATTR_RO(decomp_complete);
  NX842DEV_COUNTER_ATTR_RO(decomp_failed);
  NX842DEV_COUNTER_ATTR_RO(swdecomp);
  
  static ssize_t nx842_timehist_show(struct device *,
  		struct device_attribute *, char *);
  
  static struct device_attribute dev_attr_comp_times = __ATTR(comp_times, 0444,
  		nx842_timehist_show, NULL);
  static struct device_attribute dev_attr_decomp_times = __ATTR(decomp_times,
  		0444, nx842_timehist_show, NULL);
  
  static ssize_t nx842_timehist_show(struct device *dev,
  		struct device_attribute *attr, char *buf) {
  	char *p = buf;
  	struct nx842_devdata *local_devdata;
  	atomic64_t *times;
  	int bytes_remain = PAGE_SIZE;
  	int bytes;
  	int i;
  
  	rcu_read_lock();
  	local_devdata = rcu_dereference(devdata);
  	if (!local_devdata) {
  		rcu_read_unlock();
  		return 0;
  	}
  
  	if (attr == &dev_attr_comp_times)
  		times = local_devdata->counters->comp_times;
  	else if (attr == &dev_attr_decomp_times)
  		times = local_devdata->counters->decomp_times;
  	else {
  		rcu_read_unlock();
  		return 0;
  	}
  
  	for (i = 0; i < (NX842_HIST_SLOTS - 2); i++) {
  		bytes = snprintf(p, bytes_remain, "%u-%uus:\t%ld\n",
  			       i ? (2<<(i-1)) : 0, (2<<i)-1,
  			       atomic64_read(&times[i]));
  		bytes_remain -= bytes;
  		p += bytes;
  	}
  	/* The last bucket holds everything over
  	 * 2<<(NX842_HIST_SLOTS - 2) us */
  	bytes = snprintf(p, bytes_remain, "%uus - :\t%ld\n",
  			2<<(NX842_HIST_SLOTS - 2),
  			atomic64_read(&times[(NX842_HIST_SLOTS - 1)]));
  	p += bytes;
  
  	rcu_read_unlock();
  	return p - buf;
  }
  
  static struct attribute *nx842_sysfs_entries[] = {
  	&dev_attr_comp_complete.attr,
  	&dev_attr_comp_failed.attr,
  	&dev_attr_decomp_complete.attr,
  	&dev_attr_decomp_failed.attr,
  	&dev_attr_swdecomp.attr,
  	&dev_attr_comp_times.attr,
  	&dev_attr_decomp_times.attr,
  	NULL,
  };
  
  static struct attribute_group nx842_attribute_group = {
  	.name = NULL,		/* put in device directory */
  	.attrs = nx842_sysfs_entries,
  };
  
  static int __init nx842_probe(struct vio_dev *viodev,
  				  const struct vio_device_id *id)
  {
  	struct nx842_devdata *old_devdata, *new_devdata = NULL;
  	unsigned long flags;
  	int ret = 0;
  
  	spin_lock_irqsave(&devdata_mutex, flags);
  	old_devdata = rcu_dereference_check(devdata,
  			lockdep_is_held(&devdata_mutex));
  
  	if (old_devdata && old_devdata->vdev != NULL) {
  		dev_err(&viodev->dev, "%s: Attempt to register more than one instance of the hardware\n", __func__);
  		ret = -1;
  		goto error_unlock;
  	}
  
  	dev_set_drvdata(&viodev->dev, NULL);
  
  	new_devdata = kzalloc(sizeof(*new_devdata), GFP_NOFS);
  	if (!new_devdata) {
  		dev_err(&viodev->dev, "%s: Could not allocate memory for device data\n", __func__);
  		ret = -ENOMEM;
  		goto error_unlock;
  	}
  
  	new_devdata->counters = kzalloc(sizeof(*new_devdata->counters),
  			GFP_NOFS);
  	if (!new_devdata->counters) {
  		dev_err(&viodev->dev, "%s: Could not allocate memory for performance counters\n", __func__);
  		ret = -ENOMEM;
  		goto error_unlock;
  	}
  
  	new_devdata->vdev = viodev;
  	new_devdata->dev = &viodev->dev;
  	nx842_OF_set_defaults(new_devdata);
  
  	rcu_assign_pointer(devdata, new_devdata);
  	spin_unlock_irqrestore(&devdata_mutex, flags);
  	synchronize_rcu();
  	kfree(old_devdata);
  
  	of_reconfig_notifier_register(&nx842_of_nb);
  
  	ret = nx842_OF_upd(NULL);
  	if (ret && ret != -ENODEV) {
  		dev_err(&viodev->dev, "could not parse device tree. %d\n", ret);
  		ret = -1;
  		goto error;
  	}
  
  	rcu_read_lock();
  	dev_set_drvdata(&viodev->dev, rcu_dereference(devdata));
  	rcu_read_unlock();
  
  	if (sysfs_create_group(&viodev->dev.kobj, &nx842_attribute_group)) {
  		dev_err(&viodev->dev, "could not create sysfs device attributes\n");
  		ret = -1;
  		goto error;
  	}
  
  	return 0;
  
  error_unlock:
  	spin_unlock_irqrestore(&devdata_mutex, flags);
  	if (new_devdata)
  		kfree(new_devdata->counters);
  	kfree(new_devdata);
  error:
  	return ret;
  }
  
  static int __exit nx842_remove(struct vio_dev *viodev)
  {
  	struct nx842_devdata *old_devdata;
  	unsigned long flags;
  
  	pr_info("Removing IBM Power 842 compression device\n");
  	sysfs_remove_group(&viodev->dev.kobj, &nx842_attribute_group);
  
  	spin_lock_irqsave(&devdata_mutex, flags);
  	old_devdata = rcu_dereference_check(devdata,
  			lockdep_is_held(&devdata_mutex));
  	of_reconfig_notifier_unregister(&nx842_of_nb);
  	RCU_INIT_POINTER(devdata, NULL);
  	spin_unlock_irqrestore(&devdata_mutex, flags);
  	synchronize_rcu();
  	dev_set_drvdata(&viodev->dev, NULL);
  	if (old_devdata)
  		kfree(old_devdata->counters);
  	kfree(old_devdata);
  	return 0;
  }
  
  static struct vio_device_id nx842_driver_ids[] = {
  	{"ibm,compression-v1", "ibm,compression"},
  	{"", ""},
  };
  
  static struct vio_driver nx842_driver = {
  	.name = MODULE_NAME,
  	.probe = nx842_probe,
  	.remove = __exit_p(nx842_remove),
  	.get_desired_dma = nx842_get_desired_dma,
  	.id_table = nx842_driver_ids,
  };
  
  static int __init nx842_init(void)
  {
  	struct nx842_devdata *new_devdata;
  	pr_info("Registering IBM Power 842 compression driver\n");
  
  	RCU_INIT_POINTER(devdata, NULL);
  	new_devdata = kzalloc(sizeof(*new_devdata), GFP_KERNEL);
  	if (!new_devdata) {
  		pr_err("Could not allocate memory for device data\n");
  		return -ENOMEM;
  	}
  	new_devdata->status = UNAVAILABLE;
  	RCU_INIT_POINTER(devdata, new_devdata);
  
  	return vio_register_driver(&nx842_driver);
  }
  
  module_init(nx842_init);
  
  static void __exit nx842_exit(void)
  {
  	struct nx842_devdata *old_devdata;
  	unsigned long flags;
  
  	pr_info("Exiting IBM Power 842 compression driver\n");
  	spin_lock_irqsave(&devdata_mutex, flags);
  	old_devdata = rcu_dereference_check(devdata,
  			lockdep_is_held(&devdata_mutex));
  	RCU_INIT_POINTER(devdata, NULL);
  	spin_unlock_irqrestore(&devdata_mutex, flags);
  	synchronize_rcu();
  	if (old_devdata)
  		dev_set_drvdata(old_devdata->dev, NULL);
  	kfree(old_devdata);
  	vio_unregister_driver(&nx842_driver);
  }
  
  module_exit(nx842_exit);
  
  /*********************************
   * 842 software decompressor
  *********************************/
  typedef int (*sw842_template_op)(const char **, int *, unsigned char **,
  						struct sw842_fifo *);
  
  static int sw842_data8(const char **, int *, unsigned char **,
  						struct sw842_fifo *);
  static int sw842_data4(const char **, int *, unsigned char **,
  						struct sw842_fifo *);
  static int sw842_data2(const char **, int *, unsigned char **,
  						struct sw842_fifo *);
  static int sw842_ptr8(const char **, int *, unsigned char **,
  						struct sw842_fifo *);
  static int sw842_ptr4(const char **, int *, unsigned char **,
  						struct sw842_fifo *);
  static int sw842_ptr2(const char **, int *, unsigned char **,
  						struct sw842_fifo *);
  
  /* special templates */
  #define SW842_TMPL_REPEAT 0x1B
  #define SW842_TMPL_ZEROS 0x1C
  #define SW842_TMPL_EOF 0x1E
  
  static sw842_template_op sw842_tmpl_ops[26][4] = {
  	{ sw842_data8, NULL}, /* 0 (00000) */
  	{ sw842_data4, sw842_data2, sw842_ptr2,  NULL},
  	{ sw842_data4, sw842_ptr2,  sw842_data2, NULL},
  	{ sw842_data4, sw842_ptr2,  sw842_ptr2,  NULL},
  	{ sw842_data4, sw842_ptr4,  NULL},
  	{ sw842_data2, sw842_ptr2,  sw842_data4, NULL},
  	{ sw842_data2, sw842_ptr2,  sw842_data2, sw842_ptr2},
  	{ sw842_data2, sw842_ptr2,  sw842_ptr2,  sw842_data2},
  	{ sw842_data2, sw842_ptr2,  sw842_ptr2,  sw842_ptr2,},
  	{ sw842_data2, sw842_ptr2,  sw842_ptr4,  NULL},
  	{ sw842_ptr2,  sw842_data2, sw842_data4, NULL}, /* 10 (01010) */
  	{ sw842_ptr2,  sw842_data4, sw842_ptr2,  NULL},
  	{ sw842_ptr2,  sw842_data2, sw842_ptr2,  sw842_data2},
  	{ sw842_ptr2,  sw842_data2, sw842_ptr2,  sw842_ptr2},
  	{ sw842_ptr2,  sw842_data2, sw842_ptr4,  NULL},
  	{ sw842_ptr2,  sw842_ptr2,  sw842_data4, NULL},
  	{ sw842_ptr2,  sw842_ptr2,  sw842_data2, sw842_ptr2},
  	{ sw842_ptr2,  sw842_ptr2,  sw842_ptr2,  sw842_data2},
  	{ sw842_ptr2,  sw842_ptr2,  sw842_ptr2,  sw842_ptr2},
  	{ sw842_ptr2,  sw842_ptr2,  sw842_ptr4,  NULL},
  	{ sw842_ptr4,  sw842_data4, NULL}, /* 20 (10100) */
  	{ sw842_ptr4,  sw842_data2, sw842_ptr2,  NULL},
  	{ sw842_ptr4,  sw842_ptr2,  sw842_data2, NULL},
  	{ sw842_ptr4,  sw842_ptr2,  sw842_ptr2,  NULL},
  	{ sw842_ptr4,  sw842_ptr4,  NULL},
  	{ sw842_ptr8,  NULL}
  };
  
  /* Software decompress helpers */
  
  static uint8_t sw842_get_byte(const char *buf, int bit)
  {
  	uint8_t tmpl;
  	uint16_t tmp;
  	tmp = htons(*(uint16_t *)(buf));
  	tmp = (uint16_t)(tmp << bit);
  	tmp = ntohs(tmp);
  	memcpy(&tmpl, &tmp, 1);
  	return tmpl;
  }
  
  static uint8_t sw842_get_template(const char **buf, int *bit)
  {
  	uint8_t byte;
  	byte = sw842_get_byte(*buf, *bit);
  	byte = byte >> 3;
  	byte &= 0x1F;
  	*buf += (*bit + 5) / 8;
  	*bit = (*bit + 5) % 8;
  	return byte;
  }
  
  /* repeat_count happens to be 5-bit too (like the template) */
  static uint8_t sw842_get_repeat_count(const char **buf, int *bit)
  {
  	uint8_t byte;
  	byte = sw842_get_byte(*buf, *bit);
  	byte = byte >> 2;
  	byte &= 0x3F;
  	*buf += (*bit + 6) / 8;
  	*bit = (*bit + 6) % 8;
  	return byte;
  }
  
  static uint8_t sw842_get_ptr2(const char **buf, int *bit)
  {
  	uint8_t ptr;
  	ptr = sw842_get_byte(*buf, *bit);
  	(*buf)++;
  	return ptr;
  }
  
  static uint16_t sw842_get_ptr4(const char **buf, int *bit,
  		struct sw842_fifo *fifo)
  {
  	uint16_t ptr;
  	ptr = htons(*(uint16_t *)(*buf));
  	ptr = (uint16_t)(ptr << *bit);
  	ptr = ptr >> 7;
  	ptr &= 0x01FF;
  	*buf += (*bit + 9) / 8;
  	*bit = (*bit + 9) % 8;
  	return ptr;
  }
  
  static uint8_t sw842_get_ptr8(const char **buf, int *bit,
  		struct sw842_fifo *fifo)
  {
  	return sw842_get_ptr2(buf, bit);
  }
  
  /* Software decompress template ops */
  
  static int sw842_data8(const char **inbuf, int *inbit,
  		unsigned char **outbuf, struct sw842_fifo *fifo)
  {
  	int ret;
  
  	ret = sw842_data4(inbuf, inbit, outbuf, fifo);
  	if (ret)
  		return ret;
  	ret = sw842_data4(inbuf, inbit, outbuf, fifo);
  	return ret;
  }
  
  static int sw842_data4(const char **inbuf, int *inbit,
  		unsigned char **outbuf, struct sw842_fifo *fifo)
  {
  	int ret;
  
  	ret = sw842_data2(inbuf, inbit, outbuf, fifo);
  	if (ret)
  		return ret;
  	ret = sw842_data2(inbuf, inbit, outbuf, fifo);
  	return ret;
  }
  
  static int sw842_data2(const char **inbuf, int *inbit,
  		unsigned char **outbuf, struct sw842_fifo *fifo)
  {
  	**outbuf = sw842_get_byte(*inbuf, *inbit);
  	(*inbuf)++;
  	(*outbuf)++;
  	**outbuf = sw842_get_byte(*inbuf, *inbit);
  	(*inbuf)++;
  	(*outbuf)++;
  	return 0;
  }
  
  static int sw842_ptr8(const char **inbuf, int *inbit,
  		unsigned char **outbuf, struct sw842_fifo *fifo)
  {
  	uint8_t ptr;
  	ptr = sw842_get_ptr8(inbuf, inbit, fifo);
  	if (!fifo->f84_full && (ptr >= fifo->f8_count))
  		return 1;
  	memcpy(*outbuf, fifo->f8[ptr], 8);
  	*outbuf += 8;
  	return 0;
  }
  
  static int sw842_ptr4(const char **inbuf, int *inbit,
  		unsigned char **outbuf, struct sw842_fifo *fifo)
  {
  	uint16_t ptr;
  	ptr = sw842_get_ptr4(inbuf, inbit, fifo);
  	if (!fifo->f84_full && (ptr >= fifo->f4_count))
  		return 1;
  	memcpy(*outbuf, fifo->f4[ptr], 4);
  	*outbuf += 4;
  	return 0;
  }
  
  static int sw842_ptr2(const char **inbuf, int *inbit,
  		unsigned char **outbuf, struct sw842_fifo *fifo)
  {
  	uint8_t ptr;
  	ptr = sw842_get_ptr2(inbuf, inbit);
  	if (!fifo->f2_full && (ptr >= fifo->f2_count))
  		return 1;
  	memcpy(*outbuf, fifo->f2[ptr], 2);
  	*outbuf += 2;
  	return 0;
  }
  
  static void sw842_copy_to_fifo(const char *buf, struct sw842_fifo *fifo)
  {
  	unsigned char initial_f2count = fifo->f2_count;
  
  	memcpy(fifo->f8[fifo->f8_count], buf, 8);
  	fifo->f4_count += 2;
  	fifo->f8_count += 1;
  
  	if (!fifo->f84_full && fifo->f4_count >= 512) {
  		fifo->f84_full = 1;
  		fifo->f4_count /= 512;
  	}
  
  	memcpy(fifo->f2[fifo->f2_count++], buf, 2);
  	memcpy(fifo->f2[fifo->f2_count++], buf + 2, 2);
  	memcpy(fifo->f2[fifo->f2_count++], buf + 4, 2);
  	memcpy(fifo->f2[fifo->f2_count++], buf + 6, 2);
  	if (fifo->f2_count < initial_f2count)
  		fifo->f2_full = 1;
  }
  
  static int sw842_decompress(const unsigned char *src, int srclen,
  			unsigned char *dst, int *destlen,
  			const void *wrkmem)
  {
  	uint8_t tmpl;
  	const char *inbuf;
  	int inbit = 0;
  	unsigned char *outbuf, *outbuf_end, *origbuf, *prevbuf;
  	const char *inbuf_end;
  	sw842_template_op op;
  	int opindex;
  	int i, repeat_count;
  	struct sw842_fifo *fifo;
  	int ret = 0;
  
  	fifo = &((struct nx842_workmem *)(wrkmem))->swfifo;
  	memset(fifo, 0, sizeof(*fifo));
  
  	origbuf = NULL;
  	inbuf = src;
  	inbuf_end = src + srclen;
  	outbuf = dst;
  	outbuf_end = dst + *destlen;
  
  	while ((tmpl = sw842_get_template(&inbuf, &inbit)) != SW842_TMPL_EOF) {
  		if (inbuf >= inbuf_end) {
  			ret = -EINVAL;
  			goto out;
  		}
  
  		opindex = 0;
  		prevbuf = origbuf;
  		origbuf = outbuf;
  		switch (tmpl) {
  		case SW842_TMPL_REPEAT:
  			if (prevbuf == NULL) {
  				ret = -EINVAL;
  				goto out;
  			}
  
  			repeat_count = sw842_get_repeat_count(&inbuf,
  								&inbit) + 1;
  
  			/* Did the repeat count advance past the end of input */
  			if (inbuf > inbuf_end) {
  				ret = -EINVAL;
  				goto out;
  			}
  
  			for (i = 0; i < repeat_count; i++) {
  				/* Would this overflow the output buffer */
  				if ((outbuf + 8) > outbuf_end) {
  					ret = -ENOSPC;
  					goto out;
  				}
  
  				memcpy(outbuf, prevbuf, 8);
  				sw842_copy_to_fifo(outbuf, fifo);
  				outbuf += 8;
  			}
  			break;
  
  		case SW842_TMPL_ZEROS:
  			/* Would this overflow the output buffer */
  			if ((outbuf + 8) > outbuf_end) {
  				ret = -ENOSPC;
  				goto out;
  			}
  
  			memset(outbuf, 0, 8);
  			sw842_copy_to_fifo(outbuf, fifo);
  			outbuf += 8;
  			break;
  
  		default:
  			if (tmpl > 25) {
  				ret = -EINVAL;
  				goto out;
  			}
  
  			/* Does this go past the end of the input buffer */
  			if ((inbuf + 2) > inbuf_end) {
  				ret = -EINVAL;
  				goto out;
  			}
  
  			/* Would this overflow the output buffer */
  			if ((outbuf + 8) > outbuf_end) {
  				ret = -ENOSPC;
  				goto out;
  			}
  
  			while (opindex < 4 &&
  				(op = sw842_tmpl_ops[tmpl][opindex++])
  					!= NULL) {
  				ret = (*op)(&inbuf, &inbit, &outbuf, fifo);
  				if (ret) {
  					ret = -EINVAL;
  					goto out;
  				}
  				sw842_copy_to_fifo(origbuf, fifo);
  			}
  		}
  	}
  
  out:
  	if (!ret)
  		*destlen = (unsigned int)(outbuf - dst);
  	else
  		*destlen = 0;
  
  	return ret;
  }
  