/* Copyright (c) 2010-2012, Code Aurora Forum. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 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.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/debugfs.h>
#include <linux/list.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>
#include <linux/string.h>
#include <linux/clk.h>

#include <mach/msm_xo.h>
#include <mach/rpm.h>
#include <mach/socinfo.h>

#include "rpm_resources.h"

static DEFINE_MUTEX(msm_xo_lock);

struct msm_xo {
	unsigned votes[NUM_MSM_XO_MODES];
	unsigned mode;
	struct list_head voters;
};

struct msm_xo_voter {
	const char *name;
	unsigned mode;
	struct msm_xo *xo;
	struct list_head list;
};

static struct msm_xo msm_xo_sources[NUM_MSM_XO_IDS];

#ifdef CONFIG_DEBUG_FS
static const char *msm_xo_to_str[NUM_MSM_XO_IDS] = {
	[MSM_XO_TCXO_D0] = "D0",
	[MSM_XO_TCXO_D1] = "D1",
	[MSM_XO_TCXO_A0] = "A0",
	[MSM_XO_TCXO_A1] = "A1",
	[MSM_XO_TCXO_A2] = "A2",
	[MSM_XO_CORE] = "CORE",
};

static const char *msm_xo_mode_to_str[NUM_MSM_XO_MODES] = {
	[MSM_XO_MODE_ON] = "ON",
	[MSM_XO_MODE_PIN_CTRL] = "PIN",
	[MSM_XO_MODE_OFF] = "OFF",
};

static int msm_xo_debugfs_open(struct inode *inode, struct file *filp)
{
	filp->private_data = inode->i_private;
	return 0;
}

static ssize_t msm_xo_debugfs_read(struct file *filp, char __user *ubuf,
		size_t cnt, loff_t *ppos)
{
	int r;
	char buf[10];
	struct msm_xo_voter *xo = filp->private_data;

	r = snprintf(buf, sizeof(buf), "%s\n", msm_xo_mode_to_str[xo->mode]);
	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}

static ssize_t msm_xo_debugfs_write(struct file *filp,
		const char __user *ubuf, size_t cnt, loff_t *ppos)
{
	struct msm_xo_voter *xo = filp->private_data;
	char buf[10], *b;
	int i, ret;

	if (cnt > sizeof(buf) - 1)
		return -EINVAL;

	if (copy_from_user(&buf, ubuf, cnt))
		return -EFAULT;
	buf[cnt] = '\0';
	b = strstrip(buf);

	for (i = 0; i < ARRAY_SIZE(msm_xo_mode_to_str); i++)
		if (!strncasecmp(b, msm_xo_mode_to_str[i], sizeof(buf))) {
			ret = msm_xo_mode_vote(xo, i);
			return ret ? : cnt;
		}

	return -EINVAL;
}

static const struct file_operations msm_xo_debugfs_fops = {
	.open	= msm_xo_debugfs_open,
	.read	= msm_xo_debugfs_read,
	.write	= msm_xo_debugfs_write,
};

static struct dentry *xo_debugfs_root;
static struct msm_xo_voter *xo_debugfs_voters[NUM_MSM_XO_IDS];

static int __init msm_xo_init_debugfs_voters(void)
{
	int i;

	xo_debugfs_root = debugfs_create_dir("msm_xo", NULL);
	if (!xo_debugfs_root)
		return -ENOMEM;

	for (i = 0; i < ARRAY_SIZE(msm_xo_sources); i++) {
		xo_debugfs_voters[i] = msm_xo_get(i, "debugfs");
		if (IS_ERR(xo_debugfs_voters[i]))
			goto err;
		debugfs_create_file(msm_xo_to_str[i], S_IRUGO | S_IWUSR,
				xo_debugfs_root, xo_debugfs_voters[i],
				&msm_xo_debugfs_fops);
	}
	return 0;
err:
	while (--i >= 0)
		msm_xo_put(xo_debugfs_voters[i]);
	debugfs_remove_recursive(xo_debugfs_root);
	return -ENOMEM;
}

static void msm_xo_dump_xo(struct seq_file *m, struct msm_xo *xo,
		const char *name)
{
	struct msm_xo_voter *voter;

	seq_printf(m, "CXO %-16s%s\n", name, msm_xo_mode_to_str[xo->mode]);
	list_for_each_entry(voter, &xo->voters, list)
		seq_printf(m, " %s %-16s %s\n",
				xo->mode == voter->mode ? "*" : " ",
				voter->name,
				msm_xo_mode_to_str[voter->mode]);
}

static int msm_xo_show_voters(struct seq_file *m, void *v)
{
	int i;

	mutex_lock(&msm_xo_lock);
	for (i = 0; i < ARRAY_SIZE(msm_xo_sources); i++)
		msm_xo_dump_xo(m, &msm_xo_sources[i], msm_xo_to_str[i]);
	mutex_unlock(&msm_xo_lock);

	return 0;
}

static int msm_xo_voters_open(struct inode *inode, struct file *file)
{
	return single_open(file, msm_xo_show_voters, inode->i_private);
}

static const struct file_operations msm_xo_voters_ops = {
	.open		= msm_xo_voters_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= seq_release,
};

static int __init msm_xo_debugfs_init(void)
{
	msm_xo_init_debugfs_voters();
	if (!debugfs_create_file("xo_voters", S_IRUGO, NULL, NULL,
			&msm_xo_voters_ops))
		return -ENOMEM;
	return 0;
}
#else
static int __init msm_xo_debugfs_init(void) { return 0; }
#endif

static int msm_xo_update_vote(struct msm_xo *xo)
{
	int ret;
	unsigned vote, prev_vote = xo->mode;
	struct msm_rpm_iv_pair cmd;

	if (xo->votes[MSM_XO_MODE_ON])
		vote = MSM_XO_MODE_ON;
	else if (xo->votes[MSM_XO_MODE_PIN_CTRL])
		vote = MSM_XO_MODE_PIN_CTRL;
	else
		vote = MSM_XO_MODE_OFF;

	if (vote == prev_vote)
		return 0;

	/*
	 * Change the vote here to simplify the TCXO logic. If the RPM
	 * command fails we'll rollback.
	 */
	xo->mode = vote;
	cmd.id = MSM_RPM_ID_CXO_BUFFERS;
	cmd.value = (msm_xo_sources[MSM_XO_TCXO_D0].mode << 0)  |
		    (msm_xo_sources[MSM_XO_TCXO_D1].mode << 8)  |
		    (msm_xo_sources[MSM_XO_TCXO_A0].mode << 16) |
		    (msm_xo_sources[MSM_XO_TCXO_A1].mode << 24) |
		    (msm_xo_sources[MSM_XO_TCXO_A2].mode << 28) |
		    /*
		     * 8660 RPM has XO_CORE at bit 18 and 8960 RPM has
		     * XO_CORE at bit 20. Since the opposite bit is
		     * reserved in both cases, just set both and be
		     * done with it.
		     */
		    ((msm_xo_sources[MSM_XO_CORE].mode ? 1 : 0) << 20) |
		    ((msm_xo_sources[MSM_XO_CORE].mode ? 1 : 0) << 18);
	ret = msm_rpm_set(MSM_RPM_CTX_SET_0, &cmd, 1);

	if (ret)
		xo->mode = prev_vote;

	return ret;
}

static int __msm_xo_mode_vote(struct msm_xo_voter *xo_voter, unsigned mode)
{
	int ret;
	struct msm_xo *xo = xo_voter->xo;
	int is_d0 = xo == &msm_xo_sources[MSM_XO_TCXO_D0];
	int needs_workaround = cpu_is_msm8960() || cpu_is_apq8064() ||
			       cpu_is_msm8930() || cpu_is_msm9615();

	if (xo_voter->mode == mode)
		return 0;

	xo->votes[mode]++;
	xo->votes[xo_voter->mode]--;
	ret = msm_xo_update_vote(xo);
	if (ret) {
		xo->votes[xo_voter->mode]++;
		xo->votes[mode]--;
		goto out;
	}
	/* TODO: Remove once RPM separates the concept of D0 and CXO */
	if (is_d0 && needs_workaround) {
		static struct clk *xo_clk;

		if (!xo_clk) {
			xo_clk = clk_get_sys("msm_xo", "xo");
			BUG_ON(IS_ERR(xo_clk));
		}
		/* Ignore transitions from pin to on or vice versa */
		if (mode && xo_voter->mode == MSM_XO_MODE_OFF)
			clk_enable(xo_clk);
		else if (!mode)
			clk_disable(xo_clk);
	}
	xo_voter->mode = mode;
out:
	return ret;
}

/**
 * msm_xo_mode_vote() - Vote for an XO to be ON, OFF, or under PIN_CTRL
 * @xo_voter - Valid handle returned from msm_xo_get()
 * @mode - Mode to vote for (ON, OFF, PIN_CTRL)
 *
 * Vote for an XO to be either ON, OFF, or under PIN_CTRL. Votes are
 * aggregated with ON taking precedence over PIN_CTRL taking precedence
 * over OFF.
 *
 * This function returns 0 on success or a negative error code on failure.
 */
int msm_xo_mode_vote(struct msm_xo_voter *xo_voter, enum msm_xo_modes mode)
{
	int ret;

	if (!xo_voter)
		return 0;

	if (mode >= NUM_MSM_XO_MODES || IS_ERR(xo_voter))
		return -EINVAL;

	mutex_lock(&msm_xo_lock);
	ret = __msm_xo_mode_vote(xo_voter, mode);
	mutex_unlock(&msm_xo_lock);

	return ret;
}
EXPORT_SYMBOL(msm_xo_mode_vote);

/**
 * msm_xo_get() - Get a voting handle for an XO
 * @xo_id - XO identifier
 * @voter - Debug string to identify users
 *
 * XO voters vote for OFF by default. This function returns a pointer
 * indicating success. An ERR_PTR is returned on failure.
 *
 * If XO voting is disabled, %NULL is returned.
 */
struct msm_xo_voter *msm_xo_get(enum msm_xo_ids xo_id, const char *voter)
{
	int ret;
	struct msm_xo_voter *xo_voter;

	if (xo_id >= NUM_MSM_XO_IDS) {
		ret = -EINVAL;
		goto err;
	}

	xo_voter = kzalloc(sizeof(*xo_voter), GFP_KERNEL);
	if (!xo_voter) {
		ret = -ENOMEM;
		goto err;
	}

	xo_voter->name = kstrdup(voter, GFP_KERNEL);
	if (!xo_voter->name) {
		ret = -ENOMEM;
		goto err_name;
	}

	xo_voter->xo = &msm_xo_sources[xo_id];

	/* Voters vote for OFF by default */
	mutex_lock(&msm_xo_lock);
	xo_voter->xo->votes[MSM_XO_MODE_OFF]++;
	list_add(&xo_voter->list, &xo_voter->xo->voters);
	mutex_unlock(&msm_xo_lock);

	return xo_voter;

err_name:
	kfree(xo_voter);
err:
	return ERR_PTR(ret);
}
EXPORT_SYMBOL(msm_xo_get);

/**
 * msm_xo_put() - Release a voting handle
 * @xo_voter - Valid handle returned from msm_xo_get()
 *
 * Release a reference to an XO voting handle. This also removes the voter's
 * vote, therefore calling msm_xo_mode_vote(xo_voter, MSM_XO_MODE_OFF)
 * beforehand is unnecessary.
 */
void msm_xo_put(struct msm_xo_voter *xo_voter)
{
	if (!xo_voter || IS_ERR(xo_voter))
		return;

	mutex_lock(&msm_xo_lock);
	__msm_xo_mode_vote(xo_voter, MSM_XO_MODE_OFF);
	xo_voter->xo->votes[MSM_XO_MODE_OFF]--;
	list_del(&xo_voter->list);
	mutex_unlock(&msm_xo_lock);

	kfree(xo_voter->name);
	kfree(xo_voter);
}
EXPORT_SYMBOL(msm_xo_put);

int __init msm_xo_init(void)
{
	int i, ret;
	struct msm_rpm_iv_pair cmd[1];

	for (i = 0; i < ARRAY_SIZE(msm_xo_sources); i++)
		INIT_LIST_HEAD(&msm_xo_sources[i].voters);

	cmd[0].id = MSM_RPM_ID_CXO_BUFFERS;
	cmd[0].value = 0;
	ret = msm_rpmrs_set(MSM_RPM_CTX_SET_0, cmd, ARRAY_SIZE(cmd));
	if (ret)
		return ret;
	msm_xo_debugfs_init();
	return 0;
}
