/*
 * OMAP3-specific clock framework functions
 *
 * Copyright (C) 2007-2008 Texas Instruments, Inc.
 * Copyright (C) 2007-2008 Nokia Corporation
 *
 * Written by Paul Walmsley
 * Testing and integration fixes by Jouni Högander
 *
 * Parts of this code are based on code written by
 * Richard Woodruff, Tony Lindgren, Tuukka Tikkanen, Karthik Dasu
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#undef DEBUG

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/limits.h>
#include <linux/bitops.h>

#include <mach/clock.h>
#include <mach/sram.h>
#include <asm/div64.h>

#include "memory.h"
#include "clock.h"
#include "clock34xx.h"
#include "prm.h"
#include "prm-regbits-34xx.h"
#include "cm.h"
#include "cm-regbits-34xx.h"

/* CM_AUTOIDLE_PLL*.AUTO_* bit values */
#define DPLL_AUTOIDLE_DISABLE			0x0
#define DPLL_AUTOIDLE_LOW_POWER_STOP		0x1

#define MAX_DPLL_WAIT_TRIES		1000000

/**
 * omap3_dpll_recalc - recalculate DPLL rate
 * @clk: DPLL struct clk
 *
 * Recalculate and propagate the DPLL rate.
 */
static void omap3_dpll_recalc(struct clk *clk)
{
	clk->rate = omap2_get_dpll_rate(clk);

	propagate_rate(clk);
}

/* _omap3_dpll_write_clken - write clken_bits arg to a DPLL's enable bits */
static void _omap3_dpll_write_clken(struct clk *clk, u8 clken_bits)
{
	const struct dpll_data *dd;

	dd = clk->dpll_data;

	cm_rmw_reg_bits(dd->enable_mask, clken_bits << __ffs(dd->enable_mask),
			dd->control_reg);
}

/* _omap3_wait_dpll_status: wait for a DPLL to enter a specific state */
static int _omap3_wait_dpll_status(struct clk *clk, u8 state)
{
	const struct dpll_data *dd;
	int i = 0;
	int ret = -EINVAL;
	u32 idlest_mask;

	dd = clk->dpll_data;

	state <<= dd->idlest_bit;
	idlest_mask = 1 << dd->idlest_bit;

	while (((cm_read_reg(dd->idlest_reg) & idlest_mask) != state) &&
	       i < MAX_DPLL_WAIT_TRIES) {
		i++;
		udelay(1);
	}

	if (i == MAX_DPLL_WAIT_TRIES) {
		printk(KERN_ERR "clock: %s failed transition to '%s'\n",
		       clk->name, (state) ? "locked" : "bypassed");
	} else {
		pr_debug("clock: %s transition to '%s' in %d loops\n",
			 clk->name, (state) ? "locked" : "bypassed", i);

		ret = 0;
	}

	return ret;
}

/* Non-CORE DPLL (e.g., DPLLs that do not control SDRC) clock functions */

/*
 * _omap3_noncore_dpll_lock - instruct a DPLL to lock and wait for readiness
 * @clk: pointer to a DPLL struct clk
 *
 * Instructs a non-CORE DPLL to lock.  Waits for the DPLL to report
 * readiness before returning.  Will save and restore the DPLL's
 * autoidle state across the enable, per the CDP code.  If the DPLL
 * locked successfully, return 0; if the DPLL did not lock in the time
 * allotted, or DPLL3 was passed in, return -EINVAL.
 */
static int _omap3_noncore_dpll_lock(struct clk *clk)
{
	u8 ai;
	int r;

	if (clk == &dpll3_ck)
		return -EINVAL;

	pr_debug("clock: locking DPLL %s\n", clk->name);

	ai = omap3_dpll_autoidle_read(clk);

	_omap3_dpll_write_clken(clk, DPLL_LOCKED);

	if (ai) {
		/*
		 * If no downstream clocks are enabled, CM_IDLEST bit
		 * may never become active, so don't wait for DPLL to lock.
		 */
		r = 0;
		omap3_dpll_allow_idle(clk);
	} else {
		r = _omap3_wait_dpll_status(clk, 1);
		omap3_dpll_deny_idle(clk);
	};

	return r;
}

/*
 * omap3_noncore_dpll_bypass - instruct a DPLL to bypass and wait for readiness
 * @clk: pointer to a DPLL struct clk
 *
 * Instructs a non-CORE DPLL to enter low-power bypass mode.  In
 * bypass mode, the DPLL's rate is set equal to its parent clock's
 * rate.  Waits for the DPLL to report readiness before returning.
 * Will save and restore the DPLL's autoidle state across the enable,
 * per the CDP code.  If the DPLL entered bypass mode successfully,
 * return 0; if the DPLL did not enter bypass in the time allotted, or
 * DPLL3 was passed in, or the DPLL does not support low-power bypass,
 * return -EINVAL.
 */
static int _omap3_noncore_dpll_bypass(struct clk *clk)
{
	int r;
	u8 ai;

	if (clk == &dpll3_ck)
		return -EINVAL;

	if (!(clk->dpll_data->modes & (1 << DPLL_LOW_POWER_BYPASS)))
		return -EINVAL;

	pr_debug("clock: configuring DPLL %s for low-power bypass\n",
		 clk->name);

	ai = omap3_dpll_autoidle_read(clk);

	_omap3_dpll_write_clken(clk, DPLL_LOW_POWER_BYPASS);

	r = _omap3_wait_dpll_status(clk, 0);

	if (ai)
		omap3_dpll_allow_idle(clk);
	else
		omap3_dpll_deny_idle(clk);

	return r;
}

/*
 * _omap3_noncore_dpll_stop - instruct a DPLL to stop
 * @clk: pointer to a DPLL struct clk
 *
 * Instructs a non-CORE DPLL to enter low-power stop. Will save and
 * restore the DPLL's autoidle state across the stop, per the CDP
 * code.  If DPLL3 was passed in, or the DPLL does not support
 * low-power stop, return -EINVAL; otherwise, return 0.
 */
static int _omap3_noncore_dpll_stop(struct clk *clk)
{
	u8 ai;

	if (clk == &dpll3_ck)
		return -EINVAL;

	if (!(clk->dpll_data->modes & (1 << DPLL_LOW_POWER_STOP)))
		return -EINVAL;

	pr_debug("clock: stopping DPLL %s\n", clk->name);

	ai = omap3_dpll_autoidle_read(clk);

	_omap3_dpll_write_clken(clk, DPLL_LOW_POWER_STOP);

	if (ai)
		omap3_dpll_allow_idle(clk);
	else
		omap3_dpll_deny_idle(clk);

	return 0;
}

/**
 * omap3_noncore_dpll_enable - instruct a DPLL to enter bypass or lock mode
 * @clk: pointer to a DPLL struct clk
 *
 * Instructs a non-CORE DPLL to enable, e.g., to enter bypass or lock.
 * The choice of modes depends on the DPLL's programmed rate: if it is
 * the same as the DPLL's parent clock, it will enter bypass;
 * otherwise, it will enter lock.  This code will wait for the DPLL to
 * indicate readiness before returning, unless the DPLL takes too long
 * to enter the target state.  Intended to be used as the struct clk's
 * enable function.  If DPLL3 was passed in, or the DPLL does not
 * support low-power stop, or if the DPLL took too long to enter
 * bypass or lock, return -EINVAL; otherwise, return 0.
 */
static int omap3_noncore_dpll_enable(struct clk *clk)
{
	int r;

	if (clk == &dpll3_ck)
		return -EINVAL;

	if (clk->parent->rate == clk_get_rate(clk))
		r = _omap3_noncore_dpll_bypass(clk);
	else
		r = _omap3_noncore_dpll_lock(clk);

	return r;
}

/**
 * omap3_noncore_dpll_enable - instruct a DPLL to enter bypass or lock mode
 * @clk: pointer to a DPLL struct clk
 *
 * Instructs a non-CORE DPLL to enable, e.g., to enter bypass or lock.
 * The choice of modes depends on the DPLL's programmed rate: if it is
 * the same as the DPLL's parent clock, it will enter bypass;
 * otherwise, it will enter lock.  This code will wait for the DPLL to
 * indicate readiness before returning, unless the DPLL takes too long
 * to enter the target state.  Intended to be used as the struct clk's
 * enable function.  If DPLL3 was passed in, or the DPLL does not
 * support low-power stop, or if the DPLL took too long to enter
 * bypass or lock, return -EINVAL; otherwise, return 0.
 */
static void omap3_noncore_dpll_disable(struct clk *clk)
{
	if (clk == &dpll3_ck)
		return;

	_omap3_noncore_dpll_stop(clk);
}

/**
 * omap3_dpll_autoidle_read - read a DPLL's autoidle bits
 * @clk: struct clk * of the DPLL to read
 *
 * Return the DPLL's autoidle bits, shifted down to bit 0.  Returns
 * -EINVAL if passed a null pointer or if the struct clk does not
 * appear to refer to a DPLL.
 */
static u32 omap3_dpll_autoidle_read(struct clk *clk)
{
	const struct dpll_data *dd;
	u32 v;

	if (!clk || !clk->dpll_data)
		return -EINVAL;

	dd = clk->dpll_data;

	v = cm_read_reg(dd->autoidle_reg);
	v &= dd->autoidle_mask;
	v >>= __ffs(dd->autoidle_mask);

	return v;
}

/**
 * omap3_dpll_allow_idle - enable DPLL autoidle bits
 * @clk: struct clk * of the DPLL to operate on
 *
 * Enable DPLL automatic idle control.  This automatic idle mode
 * switching takes effect only when the DPLL is locked, at least on
 * OMAP3430.  The DPLL will enter low-power stop when its downstream
 * clocks are gated.  No return value.
 */
static void omap3_dpll_allow_idle(struct clk *clk)
{
	const struct dpll_data *dd;

	if (!clk || !clk->dpll_data)
		return;

	dd = clk->dpll_data;

	/*
	 * REVISIT: CORE DPLL can optionally enter low-power bypass
	 * by writing 0x5 instead of 0x1.  Add some mechanism to
	 * optionally enter this mode.
	 */
	cm_rmw_reg_bits(dd->autoidle_mask,
			DPLL_AUTOIDLE_LOW_POWER_STOP << __ffs(dd->autoidle_mask),
			dd->autoidle_reg);
}

/**
 * omap3_dpll_deny_idle - prevent DPLL from automatically idling
 * @clk: struct clk * of the DPLL to operate on
 *
 * Disable DPLL automatic idle control.  No return value.
 */
static void omap3_dpll_deny_idle(struct clk *clk)
{
	const struct dpll_data *dd;

	if (!clk || !clk->dpll_data)
		return;

	dd = clk->dpll_data;

	cm_rmw_reg_bits(dd->autoidle_mask,
			DPLL_AUTOIDLE_DISABLE << __ffs(dd->autoidle_mask),
			dd->autoidle_reg);
}

/* Clock control for DPLL outputs */

/**
 * omap3_clkoutx2_recalc - recalculate DPLL X2 output virtual clock rate
 * @clk: DPLL output struct clk
 *
 * Using parent clock DPLL data, look up DPLL state.  If locked, set our
 * rate to the dpll_clk * 2; otherwise, just use dpll_clk.
 */
static void omap3_clkoutx2_recalc(struct clk *clk)
{
	const struct dpll_data *dd;
	u32 v;
	struct clk *pclk;

	/* Walk up the parents of clk, looking for a DPLL */
	pclk = clk->parent;
	while (pclk && !pclk->dpll_data)
		pclk = pclk->parent;

	/* clk does not have a DPLL as a parent? */
	WARN_ON(!pclk);

	dd = pclk->dpll_data;

	WARN_ON(!dd->control_reg || !dd->enable_mask);

	v = __raw_readl(dd->control_reg) & dd->enable_mask;
	v >>= __ffs(dd->enable_mask);
	if (v != DPLL_LOCKED)
		clk->rate = clk->parent->rate;
	else
		clk->rate = clk->parent->rate * 2;

	if (clk->flags & RATE_PROPAGATES)
		propagate_rate(clk);
}

/* Common clock code */

/*
 * As it is structured now, this will prevent an OMAP2/3 multiboot
 * kernel from compiling.  This will need further attention.
 */
#if defined(CONFIG_ARCH_OMAP3)

static struct clk_functions omap2_clk_functions = {
	.clk_enable		= omap2_clk_enable,
	.clk_disable		= omap2_clk_disable,
	.clk_round_rate		= omap2_clk_round_rate,
	.clk_set_rate		= omap2_clk_set_rate,
	.clk_set_parent		= omap2_clk_set_parent,
	.clk_disable_unused	= omap2_clk_disable_unused,
};

/*
 * Set clocks for bypass mode for reboot to work.
 */
void omap2_clk_prepare_for_reboot(void)
{
	/* REVISIT: Not ready for 343x */
#if 0
	u32 rate;

	if (vclk == NULL || sclk == NULL)
		return;

	rate = clk_get_rate(sclk);
	clk_set_rate(vclk, rate);
#endif
}

/* REVISIT: Move this init stuff out into clock.c */

/*
 * Switch the MPU rate if specified on cmdline.
 * We cannot do this early until cmdline is parsed.
 */
static int __init omap2_clk_arch_init(void)
{
	if (!mpurate)
		return -EINVAL;

	/* REVISIT: not yet ready for 343x */
#if 0
	if (omap2_select_table_rate(&virt_prcm_set, mpurate))
		printk(KERN_ERR "Could not find matching MPU rate\n");
#endif

	recalculate_root_clocks();

	printk(KERN_INFO "Switched to new clocking rate (Crystal/DPLL3/MPU): "
	       "%ld.%01ld/%ld/%ld MHz\n",
	       (osc_sys_ck.rate / 1000000), (osc_sys_ck.rate / 100000) % 10,
	       (core_ck.rate / 1000000), (dpll1_fck.rate / 1000000)) ;

	return 0;
}
arch_initcall(omap2_clk_arch_init);

int __init omap2_clk_init(void)
{
	/* struct prcm_config *prcm; */
	struct clk **clkp;
	/* u32 clkrate; */
	u32 cpu_clkflg;

	/* REVISIT: Ultimately this will be used for multiboot */
#if 0
	if (cpu_is_omap242x()) {
		cpu_mask = RATE_IN_242X;
		cpu_clkflg = CLOCK_IN_OMAP242X;
		clkp = onchip_24xx_clks;
	} else if (cpu_is_omap2430()) {
		cpu_mask = RATE_IN_243X;
		cpu_clkflg = CLOCK_IN_OMAP243X;
		clkp = onchip_24xx_clks;
	}
#endif
	if (cpu_is_omap34xx()) {
		cpu_mask = RATE_IN_343X;
		cpu_clkflg = CLOCK_IN_OMAP343X;
		clkp = onchip_34xx_clks;

		/*
		 * Update this if there are further clock changes between ES2
		 * and production parts
		 */
		if (is_sil_rev_equal_to(OMAP3430_REV_ES1_0)) {
			/* No 3430ES1-only rates exist, so no RATE_IN_3430ES1 */
			cpu_clkflg |= CLOCK_IN_OMAP3430ES1;
		} else {
			cpu_mask |= RATE_IN_3430ES2;
			cpu_clkflg |= CLOCK_IN_OMAP3430ES2;
		}
	}

	clk_init(&omap2_clk_functions);

	for (clkp = onchip_34xx_clks;
	     clkp < onchip_34xx_clks + ARRAY_SIZE(onchip_34xx_clks);
	     clkp++) {
		if ((*clkp)->flags & cpu_clkflg)
			clk_register(*clkp);
	}

	/* REVISIT: Not yet ready for OMAP3 */
#if 0
	/* Check the MPU rate set by bootloader */
	clkrate = omap2_get_dpll_rate_24xx(&dpll_ck);
	for (prcm = rate_table; prcm->mpu_speed; prcm++) {
		if (!(prcm->flags & cpu_mask))
			continue;
		if (prcm->xtal_speed != sys_ck.rate)
			continue;
		if (prcm->dpll_speed <= clkrate)
			 break;
	}
	curr_prcm_set = prcm;
#endif

	recalculate_root_clocks();

	printk(KERN_INFO "Clocking rate (Crystal/DPLL/ARM core): "
	       "%ld.%01ld/%ld/%ld MHz\n",
	       (osc_sys_ck.rate / 1000000), (osc_sys_ck.rate / 100000) % 10,
	       (core_ck.rate / 1000000), (arm_fck.rate / 1000000));

	/*
	 * Only enable those clocks we will need, let the drivers
	 * enable other clocks as necessary
	 */
	clk_enable_init_clocks();

	/* Avoid sleeping during omap2_clk_prepare_for_reboot() */
	/* REVISIT: not yet ready for 343x */
#if 0
	vclk = clk_get(NULL, "virt_prcm_set");
	sclk = clk_get(NULL, "sys_ck");
#endif
	return 0;
}

#endif