path: root/drivers/clk/bcm/clk-kona.c

/*
 * Copyright (C) 2013 Broadcom Corporation
 * Copyright 2013 Linaro Limited
 *
 * 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 version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include "clk-kona.h"

#include <linux/delay.h>

/*
 * "Policies" affect the frequencies of bus clocks provided by a
 * CCU.  (I believe these polices are named "Deep Sleep", "Economy",
 * "Normal", and "Turbo".)  A lower policy number has lower power
 * consumption, and policy 2 is the default.
 */
#define CCU_POLICY_COUNT	4

#define CCU_ACCESS_PASSWORD      0xA5A500
#define CLK_GATE_DELAY_LOOP      2000

/* Bitfield operations */

/* Produces a mask of set bits covering a range of a 32-bit value */
static inline u32 bitfield_mask(u32 shift, u32 width)
{
	return ((1 << width) - 1) << shift;
}

/* Extract the value of a bitfield found within a given register value */
static inline u32 bitfield_extract(u32 reg_val, u32 shift, u32 width)
{
	return (reg_val & bitfield_mask(shift, width)) >> shift;
}

/* Replace the value of a bitfield found within a given register value */
static inline u32 bitfield_replace(u32 reg_val, u32 shift, u32 width, u32 val)
{
	u32 mask = bitfield_mask(shift, width);

	return (reg_val & ~mask) | (val << shift);
}

/* Divider and scaling helpers */

/*
 * Implement DIV_ROUND_CLOSEST() for 64-bit dividend and both values
 * unsigned.  Note that unlike do_div(), the remainder is discarded
 * and the return value is the quotient (not the remainder).
 */
u64 do_div_round_closest(u64 dividend, unsigned long divisor)
{
	u64 result;

	result = dividend + ((u64)divisor >> 1);
	(void)do_div(result, divisor);

	return result;
}

/* Convert a divider into the scaled divisor value it represents. */
static inline u64 scaled_div_value(struct bcm_clk_div *div, u32 reg_div)
{
	return (u64)reg_div + ((u64)1 << div->u.s.frac_width);
}

/*
 * Build a scaled divider value as close as possible to the
 * given whole part (div_value) and fractional part (expressed
 * in billionths).
 */
u64 scaled_div_build(struct bcm_clk_div *div, u32 div_value, u32 billionths)
{
	u64 combined;

	BUG_ON(!div_value);
	BUG_ON(billionths >= BILLION);

	combined = (u64)div_value * BILLION + billionths;
	combined <<= div->u.s.frac_width;

	return do_div_round_closest(combined, BILLION);
}

/* The scaled minimum divisor representable by a divider */
static inline u64
scaled_div_min(struct bcm_clk_div *div)
{
	if (divider_is_fixed(div))
		return (u64)div->u.fixed;

	return scaled_div_value(div, 0);
}

/* The scaled maximum divisor representable by a divider */
u64 scaled_div_max(struct bcm_clk_div *div)
{
	u32 reg_div;

	if (divider_is_fixed(div</