/*
 * Copyright (C) 2007 Wolfgang Grandegger <wg@grandegger.com>
 * Copyright (C) 2008 Markus Plessing <plessing@ems-wuensche.com>
 * Copyright (C) 2008 Sebastian Haas <haas@ems-wuensche.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the version 2 of the GNU General Public License
 * as published by the Free Software Foundation
 *
 * 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/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/netdevice.h>
#include <linux/delay.h>
#include <linux/pci.h>
#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/io.h>

#include "sja1000.h"

#define DRV_NAME  "ems_pci"

MODULE_AUTHOR("Sebastian Haas <haas@ems-wuenche.com>");
MODULE_DESCRIPTION("Socket-CAN driver for EMS CPC-PCI/PCIe CAN cards");
MODULE_SUPPORTED_DEVICE("EMS CPC-PCI/PCIe CAN card");
MODULE_LICENSE("GPL v2");

#define EMS_PCI_MAX_CHAN 2

struct ems_pci_card {
	int channels;

	struct pci_dev *pci_dev;
	struct net_device *net_dev[EMS_PCI_MAX_CHAN];

	void __iomem *conf_addr;
	void __iomem *base_addr;
};

#define EMS_PCI_CAN_CLOCK (16000000 / 2)

/*
 * Register definitions and descriptions are from LinCAN 0.3.3.
 *
 * PSB4610 PITA-2 bridge control registers
 */
#define PITA2_ICR           0x00	/* Interrupt Control Register */
#define PITA2_ICR_INT0      0x00000002	/* [RC] INT0 Active/Clear */
#define PITA2_ICR_INT0_EN   0x00020000	/* [RW] Enable INT0 */

#define PITA2_MISC          0x1c	/* Miscellaneous Register */
#define PITA2_MISC_CONFIG   0x04000000	/* Multiplexed parallel interface */

/*
 * The board configuration is probably following:
 * RX1 is connected to ground.
 * TX1 is not connected.
 * CLKO is not connected.
 * Setting the OCR register to 0xDA is a good idea.
 * This means  normal output mode , push-pull and the correct polarity.
 */
#define EMS_PCI_OCR         (OCR_TX0_PUSHPULL | OCR_TX1_PUSHPULL)

/*
 * In the CDR register, you should set CBP to 1.
 * You will probably also want to set the clock divider value to 7
 * (meaning direct oscillator output) because the second SJA1000 chip
 * is driven by the first one CLKOUT output.
 */
#define EMS_PCI_CDR             (CDR_CBP | CDR_CLKOUT_MASK)
#define EMS_PCI_MEM_SIZE        4096  /* Size of the remapped io-memory */
#define EMS_PCI_CAN_BASE_OFFSET 0x400 /* offset where the controllers starts */
#define EMS_PCI_CAN_CTRL_SIZE   0x200 /* memory size for each controller */

#define EMS_PCI_PORT_BYTES  0x4     /* Each register occupies 4 bytes */

#define EMS_PCI_VENDOR_ID   0x110a  /* PCI device and vendor ID */
#define EMS_PCI_DEVICE_ID   0x2104

static struct pci_device_id ems_pci_tbl[] = {
	{EMS_PCI_VENDOR_ID, EMS_PCI_DEVICE_ID, PCI_ANY_ID, PCI_ANY_ID,},
	{0,}
};
MODULE_DEVICE_TABLE(pci, ems_pci_tbl);

/*
 * Helper to read internal registers from card logic (not CAN)
 */
static u8 ems_pci_readb(struct ems_pci_card *card, unsigned int port)
{
	return readb(card->base_addr + (port * EMS_PCI_PORT_BYTES));
}

static u8 ems_pci_read_reg(const struct sja1000_priv *priv, int port)
{
	return readb(priv->reg_base + (port * EMS_PCI_PORT_BYTES));
}

static void ems_pci_write_reg(const struct sja1000_priv *priv, int port, u8 val)
{
	writeb(val, priv->reg_base + (port * EMS_PCI_PORT_BYTES));
}

static void ems_pci_post_irq(const struct sja1000_priv *priv)
{
	struct ems_pci_card *card = (struct ems_pci_card *)priv->priv;

	/* reset int flag of pita */
	writel(PITA2_ICR_INT0_EN | PITA2_ICR_INT0, card->conf_addr
		+ PITA2_ICR);
}

/*
 * Check if a CAN controller is present at the specified location
 * by trying to set 'em into the PeliCAN mode
 */
static inline int ems_pci_check_chan(const struct sja1000_priv *priv)
{
	unsigned char res;

	/* Make sure SJA1000 is in reset mode */
	ems_pci_write_reg(priv, REG_MOD, 1);

	ems_pci_write_reg(priv, REG_CDR, CDR_PELICAN);

	/* read reset-values */
	res = ems_pci_read_reg(priv, REG_CDR);

	if (res == CDR_PELICAN)
		return 1;

	return 0;
}

static void ems_pci_del_card(struct pci_dev *pdev)
{
	struct ems_pci_card *card = pci_get_drvdata(pdev);
	struct net_device *dev;
	int i = 0;

	for (i = 0; i < card->channels; i++) {
		dev = card->net_dev[i];

		if (!dev)
			continue;

		dev_info(&pdev->dev, "Removing %s.\n", dev->name);
		unregister_sja1000dev(dev);
		free_sja1000dev(dev);
	}

	if (card->base_addr != NULL)
		pci_iounmap(card->pci_dev, card->base_addr);

	if (card->conf_addr != NULL)
		pci_iounmap(card->pci_dev, card->conf_addr);

	kfree(card);

	pci_disable_device(pdev);
	pci_set_drvdata(pdev, NULL);
}

static void ems_pci_card_reset(struct ems_pci_card *card)
{
	/* Request board reset */
	writeb(0, card->base_addr);
}

/*
 * Probe PCI device for EMS CAN signature and register each available
 * CAN channel to SJA1000 Socket-CAN subsystem.
 */
static int __devinit ems_pci_add_card(struct pci_dev *pdev,
					const struct pci_device_id *ent)
{
	struct sja1000_priv *priv;
	struct net_device *dev;
	struct ems_pci_card *card;
	int err, i;

	/* Enabling PCI device */
	if (pci_enable_device(pdev) < 0) {
		dev_err(&pdev->dev, "Enabling PCI device failed\n");
		return -ENODEV;
	}

	/* Allocating card structures to hold addresses, ... */
	card = kzalloc(sizeof(struct ems_pci_card), GFP_KERNEL);
	if (card == NULL) {
		dev_err(&pdev->dev, "Unable to allocate memory\n");
		pci_disable_device(pdev);
		return -ENOMEM;
	}

	pci_set_drvdata(pdev, card);

	card->pci_dev = pdev;

	card->channels = 0;

	/* Remap PITA configuration space, and controller memory area */
	card->conf_addr = pci_iomap(pdev, 0, EMS_PCI_MEM_SIZE);
	if (card->conf_addr == NULL) {
		err = -ENOMEM;
		goto failure_cleanup;
	}

	card->base_addr = pci_iomap(pdev, 1, EMS_PCI_MEM_SIZE);
	if (card->base_addr == NULL) {
		err = -ENOMEM;
		goto failure_cleanup;
	}

	/* Configure PITA-2 parallel interface (enable MUX) */
	writel(PITA2_MISC_CONFIG, card->conf_addr + PITA2_MISC);

	/* Check for unique EMS CAN signature */
	if (ems_pci_readb(card, 0) != 0x55 ||
	    ems_pci_readb(card, 1) != 0xAA ||
	    ems_pci_readb(card, 2) != 0x01 ||
	    ems_pci_readb(card, 3) != 0xCB ||
	    ems_pci_readb(card, 4) != 0x11) {
		dev_err(&pdev->dev, "Not EMS Dr. Thomas Wuensche interface\n");
		err = -ENODEV;
		goto failure_cleanup;
	}

	ems_pci_card_reset(card);

	/* Detect available channels */
	for (i = 0; i < EMS_PCI_MAX_CHAN; i++) {
		dev = alloc_sja1000dev(0);
		if (dev == NULL) {
			err = -ENOMEM;
			goto failure_cleanup;
		}

		card->net_dev[i] = dev;
		priv = netdev_priv(dev);
		priv->priv = card;
		priv->irq_flags = IRQF_SHARED;

		dev->irq = pdev->irq;
		priv->reg_base = card->base_addr + EMS_PCI_CAN_BASE_OFFSET
					+ (i * EMS_PCI_CAN_CTRL_SIZE);

		/* Check if channel is present */
		if (ems_pci_check_chan(priv)) {
			priv->read_reg  = ems_pci_read_reg;
			priv->write_reg = ems_pci_write_reg;
			priv->post_irq  = ems_pci_post_irq;
			priv->can.clock.freq = EMS_PCI_CAN_CLOCK;
			priv->ocr = EMS_PCI_OCR;
			priv->cdr = EMS_PCI_CDR;

			SET_NETDEV_DEV(dev, &pdev->dev);

			/* Enable interrupts from card */
			writel(PITA2_ICR_INT0_EN, card->conf_addr + PITA2_ICR);

			/* Register SJA1000 device */
			err = register_sja1000dev(dev);
			if (err) {
				dev_err(&pdev->dev, "Registering device failed "
							"(err=%d)\n", err);
				free_sja1000dev(dev);
				goto failure_cleanup;
			}

			card->channels++;

			dev_info(&pdev->dev, "Channel #%d at 0x%p, irq %d\n",
					i + 1, priv->reg_base, dev->irq);
		} else {
			free_sja1000dev(dev);
		}
	}

	return 0;

failure_cleanup:
	dev_err(&pdev->dev, "Error: %d. Cleaning Up.\n", err);

	ems_pci_del_card(pdev);

	return err;
}

static struct pci_driver ems_pci_driver = {
	.name = DRV_NAME,
	.id_table = ems_pci_tbl,
	.probe = ems_pci_add_card,
	.remove = ems_pci_del_card,
};

static int __init ems_pci_init(void)
{
	return pci_register_driver(&ems_pci_driver);
}

static void __exit ems_pci_exit(void)
{
	pci_unregister_driver(&ems_pci_driver);
}

module_init(ems_pci_init);
module_exit(ems_pci_exit);