/**
    Network Driver for Beckhoff CCAT communication controller
    Copyright (C) 2014  Beckhoff Automation GmbH
    Author: Patrick Bruenn <p.bruenn@beckhoff.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 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, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include "module.h"

#define CCAT_DEVICES_MAX 5
#define CCAT_DATA_IN_4 0x038
#define CCAT_DATA_IN_N 0x7F0
#define CCAT_DATA_OUT_4 0x030
#define CCAT_DATA_BLOCK_SIZE (size_t)((CCAT_DATA_IN_N - CCAT_DATA_IN_4)/8)
#define CCAT_WRITE_BLOCK_SIZE 128
#define CCAT_FLASH_SIZE (size_t)0xE0000

/**     FUNCTION_NAME            CMD,  CLOCKS          */
#define CCAT_BULK_ERASE          0xE3, 8
#define CCAT_GET_PROM_ID         0xD5, 40
#define CCAT_READ_FLASH          0xC0, 32
#define CCAT_READ_STATUS         0xA0, 16
#define CCAT_WRITE_ENABLE        0x60, 8
#define CCAT_WRITE_FLASH         0x40, 32

/* from http://graphics.stanford.edu/~seander/bithacks.html#ReverseByteWith32Bits */
#define SWAP_BITS(B) \
	((((B) * 0x0802LU & 0x22110LU) | ((B) * 0x8020LU & 0x88440LU)) * 0x10101LU >> 16)

/**
 * wait_until_busy_reset() - wait until the busy flag was reset
 * @ioaddr: address of the CCAT Update function in PCI config space
 */
static inline void wait_until_busy_reset(void __iomem * const ioaddr)
{
	wmb();
	while (ioread8(ioaddr + 1)) {
		schedule();
	}
}

/**
 * __ccat_update_cmd() - Helper to issue a FPGA flash command
 * @ioaddr: address of the CCAT Update function in PCI config space
 * @cmd: the command identifier
 * @clocks: the number of clocks associated with the specified command
 *
 * no write memory barrier is called and the busy flag is not evaluated
 */
static inline void __ccat_update_cmd(void __iomem * const ioaddr, u8 cmd,
				     u16 clocks)
{
	iowrite8((0xff00 & clocks) >> 8, ioaddr);
	iowrite8(0x00ff & clocks, ioaddr + 0x8);
	iowrite8(cmd, ioaddr + 0x10);
}

/**
 * ccat_update_cmd() - Helper to issue a FPGA flash command
 * @ioaddr: address of the CCAT Update function in PCI config space
 * @cmd: the command identifier
 * @clocks: the number of clocks associated with the specified command
 *
 * Triggers a full flash command cycle with write memory barrier and
 * command activate. This call blocks until the busy flag is reset.
 */
static inline void ccat_update_cmd(void __iomem * const ioaddr, u8 cmd,
				   u16 clocks)
{
	__ccat_update_cmd(ioaddr, cmd, clocks);
	wmb();
	iowrite8(0xff, ioaddr + 0x7f8);
	wait_until_busy_reset(ioaddr);
}

/**
 * ccat_update_cmd_addr() - Helper to issue a FPGA flash command with address parameter
 * @ioaddr: address of the CCAT Update function in PCI config space
 * @cmd: the command identifier
 * @clocks: the number of clocks associated with the specified command
 * @addr: 24 bit address associated with the specified command
 *
 * Triggers a full flash command cycle with write memory barrier and
 * command activate. This call blocks until the busy flag is reset.
 */
static inline void ccat_update_cmd_addr(void __iomem * const ioaddr,
					u8 cmd, u16 clocks, u32 addr)
{
	const u8 addr_0 = SWAP_BITS(addr & 0xff);
	const u8 addr_1 = SWAP_BITS((addr & 0xff00) >> 8);
	const u8 addr_2 = SWAP_BITS((addr & 0xff0000) >> 16);

	__ccat_update_cmd(ioaddr, cmd, clocks);
	iowrite8(addr_2, ioaddr + 0x18);
	iowrite8(addr_1, ioaddr + 0x20);
	iowrite8(addr_0, ioaddr + 0x28);
	wmb();
	iowrite8(0xff, ioaddr + 0x7f8);
	wait_until_busy_reset(ioaddr);
}

/**
 * ccat_get_status() - Read CCAT Update status
 * @ioaddr: address of the CCAT Update function in PCI config space
 *
 * Return: the current status of the CCAT Update function
 */
static u8 ccat_get_status(void __iomem * const ioaddr)
{
	ccat_update_cmd(ioaddr, CCAT_READ_STATUS);
	return ioread8(ioaddr + 0x20);
}

/**
 * ccat_read_flash_block() - Read a block of CCAT configuration data from flash
 * @ioaddr: address of the CCAT Update function in PCI config space
 * @addr: 24 bit address of the block to read
 * @len: number of bytes to read from this block, len <= CCAT_DATA_BLOCK_SIZE
 * @buf: output buffer in user space
 *
 * Copies one block of configuration data from the CCAT FPGA's flash to
 * the user space buffer.
 * Note that the size of the FPGA's firmware is not known exactly so it
 * is very possible that the overall buffer ends with a lot of 0xff.
 *
 * Return: the number of bytes copied
 */
static int ccat_read_flash_block(void __iomem * const ioaddr,
				 const u32 addr, const u16 len,
				 char __user * const buf)
{
	u16 i;
	const u16 clocks = 8 * len;

	ccat_update_cmd_addr(ioaddr, CCAT_READ_FLASH + clocks, addr);
	for (i = 0; i < len; i++) {
		put_user(ioread8(ioaddr + CCAT_DATA_IN_4 + 8 * i), buf + i);
	}
	return len;
}

/**
 * ccat_read_flash() - Read a chunk of CCAT configuration data from flash
 * @ioaddr: address of the CCAT Update function in PCI config space
 * @buf: output buffer in user space
 * @len: number of bytes to read
 * @off: offset in the configuration data
 *
 * Copies multiple blocks of configuration data from the CCAT FPGA's
 * flash to the user space buffer.
 *
 * Return: the number of bytes copied
 */
static int ccat_read_flash(void __iomem * const ioaddr, char __user * buf,
			   u32 len, loff_t * off)
{
	const loff_t start = *off;

	while (len > CCAT_DATA_BLOCK_SIZE) {
		*off +=
		    ccat_read_flash_block(ioaddr, *off, CCAT_DATA_BLOCK_SIZE,
					  buf);
		buf += CCAT_DATA_BLOCK_SIZE;
		len -= CCAT_DATA_BLOCK_SIZE;
	}
	*off += ccat_read_flash_block(ioaddr, *off, len, buf);
	return *off - start;
}

/**
 * ccat_wait_status_cleared() - wait until CCAT status is cleared
 * @ioaddr: address of the CCAT Update function in PCI config space
 *
 * Blocks until bit 7 of the CCAT Update status is reset
 */
static void ccat_wait_status_cleared(void __iomem * const ioaddr)
{
	u8 status;

	do {
		status = ccat_get_status(ioaddr);
	} while (status & (1 << 7));
}

/**
 * ccat_write_flash_block() - Write a block of CCAT configuration data to flash
 * @ioaddr: address of the CCAT Update function in PCI config space
 * @addr: 24 bit start address in the CCAT FPGA's flash
 * @len: number of bytes to write in this block, len <= CCAT_WRITE_BLOCK_SIZE
 * @buf: input buffer
 *
 * Copies one block of configuration data to the CCAT FPGA's flash
 *
 * Return: the number of bytes copied
 */
static int ccat_write_flash_block(void __iomem * const ioaddr,
				  const u32 addr, const u16 len,
				  const char *const buf)
{
	const u16 clocks = 8 * len;
	u16 i;

	ccat_update_cmd(ioaddr, CCAT_WRITE_ENABLE);
	for (i = 0; i < len; i++) {
		iowrite8(buf[i], ioaddr + CCAT_DATA_OUT_4 + 8 * i);
	}
	ccat_update_cmd_addr(ioaddr, CCAT_WRITE_FLASH + clocks, addr);
	ccat_wait_status_cleared(ioaddr);
	return len;
}

/**
 * ccat_write_flash() - Write a new CCAT configuration to FPGA's flash
 * @update: a CCAT Update buffer containing the new FPGA configuration
 */
static void ccat_write_flash(const struct cdev_buffer *const buffer)
{
	const char *buf = buffer->data;
	u32 off = 0;
	size_t len = buffer->size;

	while (len > CCAT_WRITE_BLOCK_SIZE) {
		ccat_write_flash_block(buffer->ccdev->ioaddr, off,
				       (u16) CCAT_WRITE_BLOCK_SIZE, buf);
		off += CCAT_WRITE_BLOCK_SIZE;
		buf += CCAT_WRITE_BLOCK_SIZE;
		len -= CCAT_WRITE_BLOCK_SIZE;
	}
	ccat_write_flash_block(buffer->ccdev->ioaddr, off, (u16) len, buf);
}

static int ccat_update_release(struct inode *const i, struct file *const f)
{
	const struct cdev_buffer *const buf = f->private_data;
	void __iomem *ioaddr = buf->ccdev->ioaddr;

	if (buf->size > 0) {
		ccat_update_cmd(ioaddr, CCAT_WRITE_ENABLE);
		ccat_update_cmd(ioaddr, CCAT_BULK_ERASE);
		ccat_wait_status_cleared(ioaddr);
		ccat_write_flash(buf);
	}
	return ccat_cdev_release(i, f);
}

/**
 * ccat_update_read() - Read CCAT configuration data from flash
 * @f: file handle previously initialized with ccat_update_open()
 * @buf: buffer in user space provided for our data
 * @len: length of the user space buffer
 * @off: current offset of our file operation
 *
 * Copies data from the CCAT FPGA's configuration flash to user space.
 * Note that the size of the FPGA's firmware is not known exactly so it
 * is very possible that the overall buffer ends with a lot of 0xff.
 *
 * Return: the number of bytes written, or 0 if EOF reached
 */
static ssize_t ccat_update_read(struct file *const f, char __user * buf,
				size_t len, loff_t * off)
{
	struct cdev_buffer *buffer = f->private_data;
	const size_t iosize = buffer->ccdev->iosize;

	if (*off >= iosize) {
		return 0;
	}

	len = min(len, (size_t) (iosize - *off));

	return ccat_read_flash(buffer->ccdev->ioaddr, buf, len, off);
}

/**
 * ccat_update_write() - Write data to the CCAT FPGA's configuration flash
 * @f: file handle previously initialized with ccat_update_open()
 * @buf: buffer in user space providing the new configuration data (from *.rbf)
 * @len: length of the user space buffer
 * @off: current offset in the configuration data
 *
 * Copies data from user space (possibly a *.rbf) to the CCAT FPGA's
 * configuration flash.
 *
 * Return: the number of bytes written, or 0 if flash end is reached
 */
static ssize_t ccat_update_write(struct file *const f, const char __user * buf,
				 size_t len, loff_t * off)
{
	struct cdev_buffer *const buffer = f->private_data;

	if (*off + len > buffer->ccdev->iosize) {
		return 0;
	}

	if (copy_from_user(buffer->data + *off, buf, len)) {
		return -EFAULT;
	}

	*off += len;
	buffer->size = *off;
	return len;
}

static struct ccat_cdev dev_table[CCAT_DEVICES_MAX];
static struct ccat_class cdev_class = {
	.count = CCAT_DEVICES_MAX,
	.devices = dev_table,
	.name = "ccat_update",
	.fops = {
		 .owner = THIS_MODULE,
		 .open = ccat_cdev_open,
		 .release = ccat_update_release,
		 .read = ccat_update_read,
		 .write = ccat_update_write,
		 },
};

static int ccat_update_probe(struct ccat_function *func)
{
	static const u16 SUPPORTED_REVISION = 0x00;

	if (SUPPORTED_REVISION != func->info.rev) {
		pr_warn("CCAT Update rev. %d not supported\n", func->info.rev);
		return -ENODEV;
	}
	return ccat_cdev_probe(func, &cdev_class, CCAT_FLASH_SIZE);
}

struct ccat_driver update_driver = {
	.type = CCATINFO_EPCS_PROM,
	.probe = ccat_update_probe,
	.remove = ccat_cdev_remove,
	.cdev_class = &cdev_class,
};