/*
 * Support for the OLPC DCON and OLPC EC access
 *
 * Copyright © 2006  Advanced Micro Devices, Inc.
 * Copyright © 2007-2008  Andres Salomon <dilinger@debian.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.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include <linux/string.h>
#include <asm/geode.h>
#include <asm/olpc.h>

#ifdef CONFIG_OPEN_FIRMWARE
#include <asm/ofw.h>
#endif

struct olpc_platform_t olpc_platform_info;
EXPORT_SYMBOL_GPL(olpc_platform_info);

static DEFINE_SPINLOCK(ec_lock);

/* what the timeout *should* be (in ms) */
#define EC_BASE_TIMEOUT 20

/* the timeout that bugs in the EC might force us to actually use */
static int ec_timeout = EC_BASE_TIMEOUT;

static int __init olpc_ec_timeout_set(char *str)
{
	if (get_option(&str, &ec_timeout) != 1) {
		ec_timeout = EC_BASE_TIMEOUT;
		printk(KERN_ERR "olpc-ec:  invalid argument to "
				"'olpc_ec_timeout=', ignoring!\n");
	}
	printk(KERN_DEBUG "olpc-ec:  using %d ms delay for EC commands.\n",
			ec_timeout);
	return 1;
}
__setup("olpc_ec_timeout=", olpc_ec_timeout_set);

/*
 * These {i,o}bf_status functions return whether the buffers are full or not.
 */

static inline unsigned int ibf_status(unsigned int port)
{
	return !!(inb(port) & 0x02);
}

static inline unsigned int obf_status(unsigned int port)
{
	return inb(port) & 0x01;
}

#define wait_on_ibf(p, d) __wait_on_ibf(__LINE__, (p), (d))
static int __wait_on_ibf(unsigned int line, unsigned int port, int desired)
{
	unsigned int timeo;
	int state = ibf_status(port);

	for (timeo = ec_timeout; state != desired && timeo; timeo--) {
		mdelay(1);
		state = ibf_status(port);
	}

	if ((state == desired) && (ec_timeout > EC_BASE_TIMEOUT) &&
			timeo < (ec_timeout - EC_BASE_TIMEOUT)) {
		printk(KERN_WARNING "olpc-ec:  %d: waited %u ms for IBF!\n",
				line, ec_timeout - timeo);
	}

	return !(state == desired);
}

#define wait_on_obf(p, d) __wait_on_obf(__LINE__, (p), (d))
static int __wait_on_obf(unsigned int line, unsigned int port, int desired)
{
	unsigned int timeo;
	int state = obf_status(port);

	for (timeo = ec_timeout; state != desired && timeo; timeo--) {
		mdelay(1);
		state = obf_status(port);
	}

	if ((state == desired) && (ec_timeout > EC_BASE_TIMEOUT) &&
			timeo < (ec_timeout - EC_BASE_TIMEOUT)) {
		printk(KERN_WARNING "olpc-ec:  %d: waited %u ms for OBF!\n",
				line, ec_timeout - timeo);
	}

	return !(state == desired);
}

/*
 * This allows the kernel to run Embedded Controller commands.  The EC is
 * documented at <http://wiki.laptop.org/go/Embedded_controller>, and the
 * available EC commands are here:
 * <http://wiki.laptop.org/go/Ec_specification>.  Unfortunately, while
 * OpenFirmware's source is available, the EC's is not.
 */
int olpc_ec_cmd(unsigned char cmd, unsigned char *inbuf, size_t inlen,
		unsigned char *outbuf,  size_t outlen)
{
	unsigned long flags;
	int ret = -EIO;
	int i;

	spin_lock_irqsave(&ec_lock, flags);

	/* Clear OBF */
	for (i = 0; i < 10 && (obf_status(0x6c) == 1); i++)
		inb(0x68);
	if (i == 10) {
		printk(KERN_ERR "olpc-ec:  timeout while attempting to "
				"clear OBF flag!\n");
		goto err;
	}

	if (wait_on_ibf(0x6c, 0)) {
		printk(KERN_ERR "olpc-ec:  timeout waiting for EC to "
				"quiesce!\n");
		goto err;
	}

restart:
	/*
	 * Note that if we time out during any IBF checks, that's a failure;
	 * we have to return.  There's no way for the kernel to clear that.
	 *
	 * If we time out during an OBF check, we can restart the command;
	 * reissuing it will clear the OBF flag, and we should be alright.
	 * The OBF flag will sometimes misbehave due to what we believe
	 * is a hardware quirk..
	 */
	printk(KERN_DEBUG "olpc-ec:  running cmd 0x%x\n", cmd);
	outb(cmd, 0x6c);

	if (wait_on_ibf(0x6c, 0)) {
		printk(KERN_ERR "olpc-ec:  timeout waiting for EC to read "
				"command!\n");
		goto err;
	}

	if (inbuf && inlen) {
		/* write data to EC */
		for (i = 0; i < inlen; i++) {
			if (wait_on_ibf(0x6c, 0)) {
				printk(KERN_ERR "olpc-ec:  timeout waiting for"
						" EC accept data!\n");
				goto err;
			}
			printk(KERN_DEBUG "olpc-ec:  sending cmd arg 0x%x\n",
					inbuf[i]);
			outb(inbuf[i], 0x68);
		}
	}
	if (outbuf && outlen) {
		/* read data from EC */
		for (i = 0; i < outlen; i++) {
			if (wait_on_obf(0x6c, 1)) {
				printk(KERN_ERR "olpc-ec:  timeout waiting for"
						" EC to provide data!\n");
				goto restart;
			}
			outbuf[i] = inb(0x68);
			printk(KERN_DEBUG "olpc-ec:  received 0x%x\n",
					outbuf[i]);
		}
	}

	ret = 0;
err:
	spin_unlock_irqrestore(&ec_lock, flags);
	return ret;
}
EXPORT_SYMBOL_GPL(olpc_ec_cmd);

#ifdef CONFIG_OPEN_FIRMWARE
static void __init platform_detect(void)
{
	size_t propsize;
	__be32 rev;

	if (ofw("getprop", 4, 1, NULL, "board-revision-int", &rev, 4,
			&propsize) || propsize != 4) {
		printk(KERN_ERR "ofw: getprop call failed!\n");
		rev = cpu_to_be32(0);
	}
	olpc_platform_info.boardrev = be32_to_cpu(rev);
}
#else
static void __init platform_detect(void)
{
	/* stopgap until OFW support is added to the kernel */
	olpc_platform_info.boardrev = 0xc2;
}
#endif

static int __init olpc_init(void)
{
	unsigned char *romsig;

	/* The ioremap check is dangerous; limit what we run it on */
	if (!is_geode() || geode_has_vsa2())
		return 0;

	spin_lock_init(&ec_lock);

	romsig = ioremap(0xffffffc0, 16);
	if (!romsig)
		return 0;

	if (strncmp(romsig, "CL1   Q", 7))
		goto unmap;
	if (strncmp(romsig+6, romsig+13, 3)) {
		printk(KERN_INFO "OLPC BIOS signature looks invalid.  "
				"Assuming not OLPC\n");
		goto unmap;
	}

	printk(KERN_INFO "OLPC board with OpenFirmware %.16s\n", romsig);
	olpc_platform_info.flags |= OLPC_F_PRESENT;

	/* get the platform revision */
	platform_detect();

	/* assume B1 and above models always have a DCON */
	if (olpc_board_at_least(olpc_board(0xb1)))
		olpc_platform_info.flags |= OLPC_F_DCON;

	/* get the EC revision */
	olpc_ec_cmd(EC_FIRMWARE_REV, NULL, 0,
			(unsigned char *) &olpc_platform_info.ecver, 1);

	/* check to see if the VSA exists */
	if (geode_has_vsa2())
		olpc_platform_info.flags |= OLPC_F_VSA;

	printk(KERN_INFO "OLPC board revision %s%X (EC=%x)\n",
			((olpc_platform_info.boardrev & 0xf) < 8) ? "pre" : "",
			olpc_platform_info.boardrev >> 4,
			olpc_platform_info.ecver);

unmap:
	iounmap(romsig);
	return 0;
}

postcore_initcall(olpc_init);
