/*
 * Generic PXA PATA driver
 *
 * Copyright (C) 2010 Marek Vasut <marek.vasut@gmail.com>
 *
 *  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, 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; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/ata.h>
#include <linux/libata.h>
#include <linux/platform_device.h>
#include <linux/dmaengine.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/completion.h>

#include <scsi/scsi_host.h>

#include <linux/platform_data/ata-pxa.h>

#define DRV_NAME	"pata_pxa"
#define DRV_VERSION	"0.1"

struct pata_pxa_data {
	struct dma_chan		*dma_chan;
	dma_cookie_t		dma_cookie;
	struct completion	dma_done;
};

/*
 * DMA interrupt handler.
 */
static void pxa_ata_dma_irq(void *d)
{
	struct pata_pxa_data *pd = d;
	enum dma_status status;

	status = dmaengine_tx_status(pd->dma_chan, pd->dma_cookie, NULL);
	if (status == DMA_ERROR || status == DMA_COMPLETE)
		complete(&pd->dma_done);
}

/*
 * Prepare taskfile for submission.
 */
static enum ata_completion_errors pxa_qc_prep(struct ata_queued_cmd *qc)
{
	struct pata_pxa_data *pd = qc->ap->private_data;
	struct dma_async_tx_descriptor *tx;
	enum dma_transfer_direction dir;

	if (!(qc->flags & ATA_QCFLAG_DMAMAP))
		return AC_ERR_OK;

	dir = (qc->dma_dir == DMA_TO_DEVICE ? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM);
	tx = dmaengine_prep_slave_sg(pd->dma_chan, qc->sg, qc->n_elem, dir,
				     DMA_PREP_INTERRUPT);
	if (!tx) {
		ata_dev_err(qc->dev, "prep_slave_sg() failed\n");
		return AC_ERR_OK;
	}
	tx->callback = pxa_ata_dma_irq;
	tx->callback_param = pd;
	pd->dma_cookie = dmaengine_submit(tx);

	return AC_ERR_OK;
}

/*
 * Configure the DMA controller, load the DMA descriptors, but don't start the
 * DMA controller yet. Only issue the ATA command.
 */
static void pxa_bmdma_setup(struct ata_queued_cmd *qc)
{
	qc->ap->ops->sff_exec_command(qc->ap, &qc->tf);
}

/*
 * Execute the DMA transfer.
 */
static void pxa_bmdma_start(struct ata_queued_cmd *qc)
{
	struct pata_pxa_data *pd = qc->ap->private_data;
	init_completion(&pd->dma_done);
	dma_async_issue_pending(pd->dma_chan);
}

/*
 * Wait until the DMA transfer completes, then stop the DMA controller.
 */
static void pxa_bmdma_stop(struct ata_queued_cmd *qc)
{
	struct pata_pxa_data *pd = qc->ap->private_data;
	enum dma_status status;

	status = dmaengine_tx_status(pd->dma_chan, pd->dma_cookie, NULL);
	if (status != DMA_ERROR && status != DMA_COMPLETE &&
	    wait_for_completion_timeout(&pd->dma_done, HZ))
		ata_dev_err(qc->dev, "Timeout waiting for DMA completion!");

	dmaengine_terminate_all(pd->dma_chan);
}

/*
 * Read DMA status. The bmdma_stop() will take care of properly finishing the
 * DMA transfer so we always have DMA-complete interrupt here.
 */
static unsigned char pxa_bmdma_status(struct ata_port *ap)
{
	struct pata_pxa_data *pd = ap->private_data;
	unsigned char ret = ATA_DMA_INTR;
	struct dma_tx_state state;
	enum dma_status status;

	status = dmaengine_tx_status(pd->dma_chan, pd->dma_cookie, &state);
	if (status != DMA_COMPLETE)
		ret |= ATA_DMA_ERR;

	return ret;
}

/*
 * No IRQ register present so we do nothing.
 */
static void pxa_irq_clear(struct ata_port *ap)
{
}

/*
 * Check for ATAPI DMA. ATAPI DMA is unsupported by this driver. It's still
 * unclear why ATAPI has DMA issues.
 */
static int pxa_check_atapi_dma(struct ata_queued_cmd *qc)
{
	return -EOPNOTSUPP;
}

static struct scsi_host_template pxa_ata_sht = {
	ATA_BMDMA_SHT(DRV_NAME),
};

static struct ata_port_operations pxa_ata_port_ops = {
	.inherits		= &ata_bmdma_port_ops,
	.cable_detect		= ata_cable_40wire,

	.bmdma_setup		= pxa_bmdma_setup,
	.bmdma_start		= pxa_bmdma_start,
	.bmdma_stop		= pxa_bmdma_stop,
	.bmdma_status		= pxa_bmdma_status,

	.check_atapi_dma	= pxa_check_atapi_dma,

	.sff_irq_clear		= pxa_irq_clear,

	.qc_prep		= pxa_qc_prep,
};

static int pxa_ata_probe(struct platform_device *pdev)
{
	struct ata_host *host;
	struct ata_port *ap;
	struct pata_pxa_data *data;
	struct resource *cmd_res;
	struct resource *ctl_res;
	struct resource *dma_res;
	struct resource *irq_res;
	struct pata_pxa_pdata *pdata = dev_get_platdata(&pdev->dev);
	struct dma_slave_config	config;
	int ret = 0;

	/*
	 * Resource validation, three resources are needed:
	 *  - CMD port base address
	 *  - CTL port base address
	 *  - DMA port base address
	 *  - IRQ pin
	 */
	if (pdev->num_resources != 4) {
		dev_err(&pdev->dev, "invalid number of resources\n");
		return -EINVAL;
	}

	/*
	 * CMD port base address
	 */
	cmd_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (unlikely(cmd_res == NULL))
		return -EINVAL;

	/*
	 * CTL port base address
	 */
	ctl_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
	if (unlikely(ctl_res == NULL))
		return -EINVAL;

	/*
	 * DMA port base address
	 */
	dma_res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
	if (unlikely(dma_res == NULL))
		return -EINVAL;

	/*
	 * IRQ pin
	 */
	irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	if (unlikely(irq_res == NULL))
		return -EINVAL;

	/*
	 * Allocate the host
	 */
	host = ata_host_alloc(&pdev->dev, 1);
	if (!host)
		return -ENOMEM;

	ap		= host->ports[0];
	ap->ops		= &pxa_ata_port_ops;
	ap->pio_mask	= ATA_PIO4;
	ap->mwdma_mask	= ATA_MWDMA2;

	ap->ioaddr.cmd_addr	= devm_ioremap(&pdev->dev, cmd_res->start,
						resource_size(cmd_res));
	ap->ioaddr.ctl_addr	= devm_ioremap(&pdev->dev, ctl_res->start,
						resource_size(ctl_res));
	ap->ioaddr.bmdma_addr	= devm_ioremap(&pdev->dev, dma_res->start,
						resource_size(dma_res));

	/*
	 * Adjust register offsets
	 */
	ap->ioaddr.altstatus_addr = ap->ioaddr.ctl_addr;
	ap->ioaddr.data_addr	= ap->ioaddr.cmd_addr +
					(ATA_REG_DATA << pdata->reg_shift);
	ap->ioaddr.error_addr	= ap->ioaddr.cmd_addr +
					(ATA_REG_ERR << pdata->reg_shift);
	ap->ioaddr.feature_addr	= ap->ioaddr.cmd_addr +
					(ATA_REG_FEATURE << pdata->reg_shift);
	ap->ioaddr.nsect_addr	= ap->ioaddr.cmd_addr +
					(ATA_REG_NSECT << pdata->reg_shift);
	ap->ioaddr.lbal_addr	= ap->ioaddr.cmd_addr +
					(ATA_REG_LBAL << pdata->reg_shift);
	ap->ioaddr.lbam_addr	= ap->ioaddr.cmd_addr +
					(ATA_REG_LBAM << pdata->reg_shift);
	ap->ioaddr.lbah_addr	= ap->ioaddr.cmd_addr +
					(ATA_REG_LBAH << pdata->reg_shift);
	ap->ioaddr.device_addr	= ap->ioaddr.cmd_addr +
					(ATA_REG_DEVICE << pdata->reg_shift);
	ap->ioaddr.status_addr	= ap->ioaddr.cmd_addr +
					(ATA_REG_STATUS << pdata->reg_shift);
	ap->ioaddr.command_addr	= ap->ioaddr.cmd_addr +
					(ATA_REG_CMD << pdata->reg_shift);

	/*
	 * Allocate and load driver's internal data structure
	 */
	data = devm_kzalloc(&pdev->dev, sizeof(struct pata_pxa_data),
								GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	ap->private_data = data;

	memset(&config, 0, sizeof(config));
	config.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
	config.dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
	config.src_addr = dma_res->start;
	config.dst_addr = dma_res->start;
	config.src_maxburst = 32;
	config.dst_maxburst = 32;

	/*
	 * Request the DMA channel
	 */
	data->dma_chan =
		dma_request_slave_channel(&pdev->dev, "data");
	if (!data->dma_chan)
		return -EBUSY;
	ret = dmaengine_slave_config(data->dma_chan, &config);
	if (ret < 0) {
		dev_err(&pdev->dev, "dma configuration failed: %d\n", ret);
		return ret;
	}

	/*
	 * Activate the ATA host
	 */
	ret = ata_host_activate(host, irq_res->start, ata_sff_interrupt,
				pdata->irq_flags, &pxa_ata_sht);
	if (ret)
		dma_release_channel(data->dma_chan);

	return ret;
}

static int pxa_ata_remove(struct platform_device *pdev)
{
	struct ata_host *host = platform_get_drvdata(pdev);
	struct pata_pxa_data *data = host->ports[0]->private_data;

	dma_release_channel(data->dma_chan);

	ata_host_detach(host);

	return 0;
}

static struct platform_driver pxa_ata_driver = {
	.probe		= pxa_ata_probe,
	.remove		= pxa_ata_remove,
	.driver		= {
		.name		= DRV_NAME,
	},
};

module_platform_driver(pxa_ata_driver);

MODULE_AUTHOR("Marek Vasut <marek.vasut@gmail.com>");
MODULE_DESCRIPTION("DMA-capable driver for PATA on PXA CPU");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);
MODULE_ALIAS("platform:" DRV_NAME);