/*
 * comedi/drivers/mite.c
 * Hardware driver for NI Mite PCI interface chip
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 1997-2002 David A. Schleef <ds@schleef.org>
 *
 * 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.
 */

/*
 * The PCI-MIO E series driver was originally written by
 * Tomasz Motylewski <...>, and ported to comedi by ds.
 *
 * References for specifications:
 *
 *    321747b.pdf  Register Level Programmer Manual (obsolete)
 *    321747c.pdf  Register Level Programmer Manual (new)
 *    DAQ-STC reference manual
 *
 * Other possibly relevant info:
 *
 *    320517c.pdf  User manual (obsolete)
 *    320517f.pdf  User manual (new)
 *    320889a.pdf  delete
 *    320906c.pdf  maximum signal ratings
 *    321066a.pdf  about 16x
 *    321791a.pdf  discontinuation of at-mio-16e-10 rev. c
 *    321808a.pdf  about at-mio-16e-10 rev P
 *    321837a.pdf  discontinuation of at-mio-16de-10 rev d
 *    321838a.pdf  about at-mio-16de-10 rev N
 *
 * ISSUES:
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/slab.h>

#include "../comedi_pci.h"

#include "mite.h"

#define TOP_OF_PAGE(x) ((x)|(~(PAGE_MASK)))

struct mite_struct *mite_alloc(struct pci_dev *pcidev)
{
	struct mite_struct *mite;
	unsigned int i;

	mite = kzalloc(sizeof(*mite), GFP_KERNEL);
	if (mite) {
		spin_lock_init(&mite->lock);
		mite->pcidev = pcidev;
		for (i = 0; i < MAX_MITE_DMA_CHANNELS; ++i) {
			mite->channels[i].mite = mite;
			mite->channels[i].channel = i;
			mite->channels[i].done = 1;
		}
	}
	return mite;
}
EXPORT_SYMBOL_GPL(mite_alloc);

static void dump_chip_signature(u32 csigr_bits)
{
	pr_info("version = %i, type = %i, mite mode = %i, interface mode = %i\n",
		mite_csigr_version(csigr_bits), mite_csigr_type(csigr_bits),
		mite_csigr_mmode(csigr_bits), mite_csigr_imode(csigr_bits));
	pr_info("num channels = %i, write post fifo depth = %i, wins = %i, iowins = %i\n",
		mite_csigr_dmac(csigr_bits), mite_csigr_wpdep(csigr_bits),
		mite_csigr_wins(csigr_bits), mite_csigr_iowins(csigr_bits));
}

static unsigned mite_fifo_size(struct mite_struct *mite, unsigned channel)
{
	unsigned fcr_bits = readl(mite->mite_io_addr + MITE_FCR(channel));
	unsigned empty_count = (fcr_bits >> 16) & 0xff;
	unsigned full_count = fcr_bits & 0xff;

	return empty_count + full_count;
}

int mite_setup2(struct comedi_device *dev,
		struct mite_struct *mite, bool use_win1)
{
	unsigned long length;
	int i;
	u32 csigr_bits;
	unsigned unknown_dma_burst_bits;

	pci_set_master(mite->pcidev);

	mite->mite_io_addr = pci_ioremap_bar(mite->pcidev, 0);
	if (!mite->mite_io_addr) {
		dev_err(dev->class_dev,
			"Failed to remap mite io memory address\n");
		return -ENOMEM;
	}
	mite->mite_phys_addr = pci_resource_start(mite->pcidev, 0);

	dev->mmio = pci_ioremap_bar(mite->pcidev, 1);
	if (!dev->mmio) {
		dev_err(dev->class_dev,
			"Failed to remap daq io memory address\n");
		return -ENOMEM;
	}
	mite->daq_phys_addr = pci_resource_start(mite->pcidev, 1);
	length = pci_resource_len(mite->pcidev, 1);

	if (use_win1) {
		writel(0, mite->mite_io_addr + MITE_IODWBSR);
		dev_info(dev->class_dev,
			 "using I/O Window Base Size register 1\n");
		writel(mite->daq_phys_addr | WENAB |
		       MITE_IODWBSR_1_WSIZE_bits(length),
		       mite->mite_io_addr + MITE_IODWBSR_1);
		writel(0, mite->mite_io_addr + MITE_IODWCR_1);
	} else {
		writel(mite->daq_phys_addr | WENAB,
		       mite->mite_io_addr + MITE_IODWBSR);
	}
	/*
	 * Make sure dma bursts work. I got this from running a bus analyzer
	 * on a pxi-6281 and a pxi-6713. 6713 powered up with register value
	 * of 0x61f and bursts worked. 6281 powered up with register value of
	 * 0x1f and bursts didn't work. The NI windows driver reads the
	 * register, then does a bitwise-or of 0x600 with it and writes it back.
	 */
	unknown_dma_burst_bits =
	    readl(mite->mite_io_addr + MITE_UNKNOWN_DMA_BURST_REG);
	unknown_dma_burst_bits |= UNKNOWN_DMA_BURST_ENABLE_BITS;
	writel(unknown_dma_burst_bits,
	       mite->mite_io_addr + MITE_UNKNOWN_DMA_BURST_REG);

	csigr_bits = readl(mite->mite_io_addr + MITE_CSIGR);
	mite->num_channels = mite_csigr_dmac(csigr_bits);
	if (mite->num_channels > MAX_MITE_DMA_CHANNELS) {
		dev_warn(dev->class_dev,
			 "mite: bug? chip claims to have %i dma channels. Setting to %i.\n",
			 mite->num_channels, MAX_MITE_DMA_CHANNELS);
		mite->num_channels = MAX_MITE_DMA_CHANNELS;
	}
	dump_chip_signature(csigr_bits);
	for (i = 0; i < mite->num_channels; i++) {
		writel(CHOR_DMARESET, mite->mite_io_addr + MITE_CHOR(i));
		/* disable interrupts */
		writel(CHCR_CLR_DMA_IE | CHCR_CLR_LINKP_IE | CHCR_CLR_SAR_IE |
		       CHCR_CLR_DONE_IE | CHCR_CLR_MRDY_IE | CHCR_CLR_DRDY_IE |
		       CHCR_CLR_LC_IE | CHCR_CLR_CONT_RB_IE,
		       mite->mite_io_addr + MITE_CHCR(i));
	}
	mite->fifo_size = mite_fifo_size(mite, 0);
	dev_info(dev->class_dev, "fifo size is %i.\n", mite->fifo_size);
	return 0;
}
EXPORT_SYMBOL_GPL(mite_setup2);

void mite_detach(struct mite_struct *mite)
{
	if (!mite)
		return;

	if (mite->mite_io_addr)
		iounmap(mite->mite_io_addr);

	kfree(mite);
}
EXPORT_SYMBOL_GPL(mite_detach);

struct mite_dma_descriptor_ring *mite_alloc_ring(struct mite_struct *mite)
{
	struct mite_dma_descriptor_ring *ring =
	    kmalloc(sizeof(struct mite_dma_descriptor_ring), GFP_KERNEL);

	if (!ring)
		return NULL;
	ring->hw_dev = get_device(&mite->pcidev->dev);
	if (!ring->hw_dev) {
		kfree(ring);
		return NULL;
	}
	ring->n_links = 0;
	ring->descriptors = NULL;
	ring->descriptors_dma_addr = 0;
	return ring;
};
EXPORT_SYMBOL_GPL(mite_alloc_ring);

void mite_free_ring(struct mite_dma_descriptor_ring *ring)
{
	if (ring) {
		if (ring->descriptors) {
			dma_free_coherent(ring->hw_dev,
					  ring->n_links *
					  sizeof(struct mite_dma_descriptor),
					  ring->descriptors,
					  ring->descriptors_dma_addr);
		}
		put_device(ring->hw_dev);
		kfree(ring);
	}
};
EXPORT_SYMBOL_GPL(mite_free_ring);

struct mite_channel *mite_request_channel_in_range(struct mite_struct *mite,
						   struct
						   mite_dma_descriptor_ring
						   *ring, unsigned min_channel,
						   unsigned max_channel)
{
	int i;
	unsigned long flags;
	struct mite_channel *channel = NULL;

	/*
	 * spin lock so mite_release_channel can be called safely
	 * from interrupts
	 */
	spin_lock_irqsave(&mite->lock, flags);
	for (i = min_channel; i <= max_channel; ++i) {
		if (mite->channel_allocated[i] == 0) {
			mite->channel_allocated[i] = 1;
			channel = &mite->channels[i];
			channel->ring = ring;
			break;
		}
	}
	spin_unlock_irqrestore(&mite->lock, flags);
	return channel;
}
EXPORT_SYMBOL_GPL(mite_request_channel_in_range);

void mite_release_channel(struct mite_channel *mite_chan)
{
	struct mite_struct *mite = mite_chan->mite;
	unsigned long flags;

	/* spin lock to prevent races with mite_request_channel */
	spin_lock_irqsave(&mite->lock, flags);
	if (mite->channel_allocated[mite_chan->channel]) {
		mite_dma_disarm(mite_chan);
		mite_dma_reset(mite_chan);
		/*
		 * disable all channel's interrupts (do it after disarm/reset so
		 * MITE_CHCR reg isn't changed while dma is still active!)
		 */
		writel(CHCR_CLR_DMA_IE | CHCR_CLR_LINKP_IE |
		       CHCR_CLR_SAR_IE | CHCR_CLR_DONE_IE |
		       CHCR_CLR_MRDY_IE | CHCR_CLR_DRDY_IE |
		       CHCR_CLR_LC_IE | CHCR_CLR_CONT_RB_IE,
		       mite->mite_io_addr + MITE_CHCR(mite_chan->channel));
		mite->channel_allocated[mite_chan->channel] = 0;
		mite_chan->ring = NULL;
		mmiowb();
	}
	spin_unlock_irqrestore(&mite->lock, flags);
}
EXPORT_SYMBOL_GPL(mite_release_channel);

void mite_dma_arm(struct mite_channel *mite_chan)
{
	struct mite_struct *mite = mite_chan->mite;
	int chor;
	unsigned long flags;

	/*
	 * memory barrier is intended to insure any twiddling with the buffer
	 * is done before writing to the mite to arm dma transfer
	 */
	smp_mb();
	/* arm */
	chor = CHOR_START;
	spin_lock_irqsave(&mite->lock, flags);
	mite_chan->done = 0;
	writel(chor, mite->mite_io_addr + MITE_CHOR(mite_chan->channel));
	mmiowb();
	spin_unlock_irqrestore(&mite->lock, flags);
	/* mite_dma_tcr(mite, channel); */
}
EXPORT_SYMBOL_GPL(mite_dma_arm);

/**************************************/

int mite_buf_change(struct mite_dma_descriptor_ring *ring,
		    struct comedi_subdevice *s)
{
	struct comedi_async *async = s->async;
	unsigned int n_links;
	int i;

	if (ring->descriptors) {
		dma_free_coherent(ring->hw_dev,
				  ring->n_links *
				  sizeof(struct mite_dma_descriptor),
				  ring->descriptors,
				  ring->descriptors_dma_addr);
	}
	ring->descriptors = NULL;
	ring->descriptors_dma_addr = 0;
	ring->n_links = 0;

	if (async->prealloc_bufsz == 0)
		return 0;

	n_links = async->prealloc_bufsz >> PAGE_SHIFT;

	ring->descriptors =
	    dma_alloc_coherent(ring->hw_dev,
			       n_links * sizeof(struct mite_dma_descriptor),
			       &ring->descriptors_dma_addr, GFP_KERNEL);
	if (!ring->descriptors) {
		dev_err(s->device->class_dev,
			"mite: ring buffer allocation failed\n");
		return -ENOMEM;
	}
	ring->n_links = n_links;

	for (i = 0; i < n_links; i++) {
		ring->descriptors[i].count = cpu_to_le32(PAGE_SIZE);
		ring->descriptors[i].addr =
		    cpu_to_le32(async->buf_map->page_list[i].dma_addr);
		ring->descriptors[i].next =
		    cpu_to_le32(ring->descriptors_dma_addr + (i +
							      1) *
				sizeof(struct mite_dma_descriptor));
	}
	ring->descriptors[n_links - 1].next =
	    cpu_to_le32(ring->descriptors_dma_addr);
	/*
	 * barrier is meant to insure that all the writes to the dma descriptors
	 * have completed before the dma controller is commanded to read them
	 */
	smp_wmb();
	return 0;
}
EXPORT_SYMBOL_GPL(mite_buf_change);

void mite_prep_dma(struct mite_channel *mite_chan,
		   unsigned int num_device_bits, unsigned int num_memory_bits)
{
	unsigned int chor, chcr, mcr, dcr, lkcr;
	struct mite_struct *mite = mite_chan->mite;

	/* reset DMA and FIFO */
	chor = CHOR_DMARESET | CHOR_FRESET;
	writel(chor, mite->mite_io_addr + MITE_CHOR(mite_chan->channel));

	/* short link chaining mode */
	chcr = CHCR_SET_DMA_IE | CHCR_LINKSHORT | CHCR_SET_DONE_IE |
	    CHCR_BURSTEN;
	/*
	 * Link Complete Interrupt: interrupt every time a link
	 * in MITE_RING is completed. This can generate a lot of
	 * extra interrupts, but right now we update the values
	 * of buf_int_ptr and buf_int_count at each interrupt. A
	 * better method is to poll the MITE before each user
	 * "read()" to calculate the number of bytes available.
	 */
	chcr |= CHCR_SET_LC_IE;
	if (num_memory_bits == 32 && num_device_bits == 16) {
		/*
		 * Doing a combined 32 and 16 bit byteswap gets the 16 bit
		 * samples into the fifo in the right order. Tested doing 32 bit
		 * memory to 16 bit device transfers to the analog out of a
		 * pxi-6281, which has mite version = 1, type = 4. This also
		 * works for dma reads from the counters on e-series boards.
		 */
		chcr |= CHCR_BYTE_SWAP_DEVICE | CHCR_BYTE_SWAP_MEMORY;
	}
	if (mite_chan->dir == COMEDI_INPUT)
		chcr |= CHCR_DEV_TO_MEM;

	writel(chcr, mite->mite_io_addr + MITE_CHCR(mite_chan->channel));

	/* to/from memory */
	mcr = CR_RL(64) | CR_ASEQUP;
	switch (num_memory_bits) {
	case 8:
		mcr |= CR_PSIZE8;
		break;
	case 16:
		mcr |= CR_PSIZE16;
		break;
	case 32:
		mcr |= CR_PSIZE32;
		break;
	default:
		pr_warn("bug! invalid mem bit width for dma transfer\n");
		break;
	}
	writel(mcr, mite->mite_io_addr + MITE_MCR(mite_chan->channel));

	/* from/to device */
	dcr = CR_RL(64) | CR_ASEQUP;
	dcr |= CR_PORTIO | CR_AMDEVICE | CR_REQSDRQ(mite_chan->channel);
	switch (num_device_bits) {
	case 8:
		dcr |= CR_PSIZE8;
		break;
	case 16:
		dcr |= CR_PSIZE16;
		break;
	case 32:
		dcr |= CR_PSIZE32;
		break;
	default:
		pr_warn("bug! invalid dev bit width for dma transfer\n");
		break;
	}
	writel(dcr, mite->mite_io_addr + MITE_DCR(mite_chan->channel));

	/* reset the DAR */
	writel(0, mite->mite_io_addr + MITE_DAR(mite_chan->channel));

	/* the link is 32bits */
	lkcr = CR_RL(64) | CR_ASEQUP | CR_PSIZE32;
	writel(lkcr, mite->mite_io_addr + MITE_LKCR(mite_chan->channel));

	/* starting address for link chaining */
	writel(mite_chan->ring->descriptors_dma_addr,
	       mite->mite_io_addr + MITE_LKAR(mite_chan->channel));
}
EXPORT_SYMBOL_GPL(mite_prep_dma);

static u32 mite_device_bytes_transferred(struct mite_channel *mite_chan)
{
	struct mite_struct *mite = mite_chan->mite;

	return readl(mite->mite_io_addr + MITE_DAR(mite_chan->channel));
}

u32 mite_bytes_in_transit(struct mite_channel *mite_chan)
{
	struct mite_struct *mite = mite_chan->mite;

	return readl(mite->mite_io_addr +
		     MITE_FCR(mite_chan->channel)) & 0x000000FF;
}
EXPORT_SYMBOL_GPL(mite_bytes_in_transit);

/* returns lower bound for number of bytes transferred from device to memory */
u32 mite_bytes_written_to_memory_lb(struct mite_channel *mite_chan)
{
	u32 device_byte_count;

	device_byte_count = mite_device_bytes_transferred(mite_chan);
	return device_byte_count - mite_bytes_in_transit(mite_chan);
}
EXPORT_SYMBOL_GPL(mite_bytes_written_to_memory_lb);

/* returns upper bound for number of bytes transferred from device to memory */
u32 mite_bytes_written_to_memory_ub(struct mite_channel *mite_chan)
{
	u32 in_transit_count;

	in_transit_count = mite_bytes_in_transit(mite_chan);
	return mite_device_bytes_transferred(mite_chan) - in_transit_count;
}
EXPORT_SYMBOL_GPL(mite_bytes_written_to_memory_ub);

/* returns lower bound for number of bytes read from memory to device */
u32 mite_bytes_read_from_memory_lb(struct mite_channel *mite_chan)
{
	u32 device_byte_count;

	device_byte_count = mite_device_bytes_transferred(mite_chan);
	return device_byte_count + mite_bytes_in_transit(mite_chan);
}
EXPORT_SYMBOL_GPL(mite_bytes_read_from_memory_lb);

/* returns upper bound for number of bytes read from memory to device */
u32 mite_bytes_read_from_memory_ub(struct mite_channel *mite_chan)
{
	u32 in_transit_count;

	in_transit_count = mite_bytes_in_transit(mite_chan);
	return mite_device_bytes_transferred(mite_chan) + in_transit_count;
}
EXPORT_SYMBOL_GPL(mite_bytes_read_from_memory_ub);

unsigned mite_dma_tcr(struct mite_channel *mite_chan)
{
	struct mite_struct *mite = mite_chan->mite;

	return readl(mite->mite_io_addr + MITE_TCR(mite_chan->channel));
}
EXPORT_SYMBOL_GPL(mite_dma_tcr);

void mite_dma_disarm(struct mite_channel *mite_chan)
{
	struct mite_struct *mite = mite_chan->mite;
	unsigned chor;

	/* disarm */
	chor = CHOR_ABORT;
	writel(chor, mite->mite_io_addr + MITE_CHOR(mite_chan->channel));
}
EXPORT_SYMBOL_GPL(mite_dma_disarm);

int mite_sync_input_dma(struct mite_channel *mite_chan,
			struct comedi_subdevice *s)
{
	struct comedi_async *async = s->async;
	int count;
	unsigned int nbytes, old_alloc_count;

	old_alloc_count = async->buf_write_alloc_count;
	/* write alloc as much as we can */
	comedi_buf_write_alloc(s, async->prealloc_bufsz);

	nbytes = mite_bytes_written_to_memory_lb(mite_chan);
	if ((int)(mite_bytes_written_to_memory_ub(mite_chan) -
		  old_alloc_count) > 0) {
		dev_warn(s->device->class_dev,
			 "mite: DMA overwrite of free area\n");
		async->events |= COMEDI_CB_OVERFLOW;
		return -1;
	}

	count = nbytes - async->buf_write_count;
	/*
	 * it's possible count will be negative due to conservative value
	 * returned by mite_bytes_written_to_memory_lb
	 */
	if (count <= 0)
		return 0;

	comedi_buf_write_free(s, count);
	comedi_inc_scan_progress(s, count);
	async->events |= COMEDI_CB_BLOCK;
	return 0;
}
EXPORT_SYMBOL_GPL(mite_sync_input_dma);

int mite_sync_output_dma(struct mite_channel *mite_chan,
			 struct comedi_subdevice *s)
{
	struct comedi_async *async = s->async;
	struct comedi_cmd *cmd = &async->cmd;
	u32 stop_count = cmd->stop_arg * comedi_bytes_per_scan(s);
	unsigned int old_alloc_count = async->buf_read_alloc_count;
	u32 nbytes_ub, nbytes_lb;
	int count;

	/* read alloc as much as we can */
	comedi_buf_read_alloc(s, async->prealloc_bufsz);
	nbytes_lb = mite_bytes_read_from_memory_lb(mite_chan);
	if (cmd->stop_src == TRIG_COUNT && (int)(nbytes_lb - stop_count) > 0)
		nbytes_lb = stop_count;
	nbytes_ub = mite_bytes_read_from_memory_ub(mite_chan);
	if (cmd->stop_src == TRIG_COUNT && (int)(nbytes_ub - stop_count) > 0)
		nbytes_ub = stop_count;
	if ((int)(nbytes_ub - old_alloc_count) > 0) {
		dev_warn(s->device->class_dev, "mite: DMA underrun\n");
		async->events |= COMEDI_CB_OVERFLOW;
		return -1;
	}
	count = nbytes_lb - async->buf_read_count;
	if (count <= 0)
		return 0;

	if (count) {
		comedi_buf_read_free(s, count);
		async->events |= COMEDI_CB_BLOCK;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(mite_sync_output_dma);

unsigned mite_get_status(struct mite_channel *mite_chan)
{
	struct mite_struct *mite = mite_chan->mite;
	unsigned status;
	unsigned long flags;

	spin_lock_irqsave(&mite->lock, flags);
	status = readl(mite->mite_io_addr + MITE_CHSR(mite_chan->channel));
	if (status & CHSR_DONE) {
		mite_chan->done = 1;
		writel(CHOR_CLRDONE,
		       mite->mite_io_addr + MITE_CHOR(mite_chan->channel));
	}
	mmiowb();
	spin_unlock_irqrestore(&mite->lock, flags);
	return status;
}
EXPORT_SYMBOL_GPL(mite_get_status);

int mite_done(struct mite_channel *mite_chan)
{
	struct mite_struct *mite = mite_chan->mite;
	unsigned long flags;
	int done;

	mite_get_status(mite_chan);
	spin_lock_irqsave(&mite->lock, flags);
	done = mite_chan->done;
	spin_unlock_irqrestore(&mite->lock, flags);
	return done;
}
EXPORT_SYMBOL_GPL(mite_done);

static int __init mite_module_init(void)
{
	return 0;
}

static void __exit mite_module_exit(void)
{
}

module_init(mite_module_init);
module_exit(mite_module_exit);

MODULE_AUTHOR("Comedi http://www.comedi.org");
MODULE_DESCRIPTION("Comedi helper for NI Mite PCI interface chip");
MODULE_LICENSE("GPL");