Release 4.11 drivers/clk/clk-multiplier.c
/*
* Copyright (C) 2015 Maxime Ripard <maxime.ripard@free-electrons.com>
*
* 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.
*/
#include <linux/bitops.h>
#include <linux/clk-provider.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/slab.h>
static unsigned long __get_mult(struct clk_multiplier *mult,
unsigned long rate,
unsigned long parent_rate)
{
if (mult->flags & CLK_MULTIPLIER_ROUND_CLOSEST)
return DIV_ROUND_CLOSEST(rate, parent_rate);
return rate / parent_rate;
}
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static unsigned long clk_multiplier_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct clk_multiplier *mult = to_clk_multiplier(hw);
unsigned long val;
val = clk_readl(mult->reg) >> mult->shift;
val &= GENMASK(mult->width - 1, 0);
if (!val && mult->flags & CLK_MULTIPLIER_ZERO_BYPASS)
val = 1;
return parent_rate * val;
}
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static bool __is_best_rate(unsigned long rate, unsigned long new,
unsigned long best, unsigned long flags)
{
if (flags & CLK_MULTIPLIER_ROUND_CLOSEST)
return abs(rate - new) < abs(rate - best);
return new >= rate && new < best;
}
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static unsigned long __bestmult(struct clk_hw *hw, unsigned long rate,
unsigned long *best_parent_rate,
u8 width, unsigned long flags)
{
struct clk_multiplier *mult = to_clk_multiplier(hw);
unsigned long orig_parent_rate = *best_parent_rate;
unsigned long parent_rate, current_rate, best_rate = ~0;
unsigned int i, bestmult = 0;
unsigned int maxmult = (1 << width) - 1;
if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
bestmult = rate / orig_parent_rate;
/* Make sure we don't end up with a 0 multiplier */
if ((bestmult == 0) &&
!(mult->flags & CLK_MULTIPLIER_ZERO_BYPASS))
bestmult = 1;
/* Make sure we don't overflow the multiplier */
if (bestmult > maxmult)
bestmult = maxmult;
return bestmult;
}
for (i = 1; i < maxmult; i++) {
if (rate == orig_parent_rate * i) {
/*
* This is the best case for us if we have a
* perfect match without changing the parent
* rate.
*/
*best_parent_rate = orig_parent_rate;
return i;
}
parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw),
rate / i);
current_rate = parent_rate * i;
if (__is_best_rate(rate, current_rate, best_rate, flags)) {
bestmult = i;
best_rate = current_rate;
*best_parent_rate = parent_rate;
}
}
return bestmult;
}
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static long clk_multiplier_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *parent_rate)
{
struct clk_multiplier *mult = to_clk_multiplier(hw);
unsigned long factor = __bestmult(hw, rate, parent_rate,
mult->width, mult->flags);
return *parent_rate * factor;
}
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static int clk_multiplier_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct clk_multiplier *mult = to_clk_multiplier(hw);
unsigned long factor = __get_mult(mult, rate, parent_rate);
unsigned long flags = 0;
unsigned long val;
if (mult->lock)
spin_lock_irqsave(mult->lock, flags);
else
__acquire(mult->lock);
val = clk_readl(mult->reg);
val &= ~GENMASK(mult->width + mult->shift - 1, mult->shift);
val |= factor << mult->shift;
clk_writel(val, mult->reg);
if (mult->lock)
spin_unlock_irqrestore(mult->lock, flags);
else
__release(mult->lock);
return 0;
}
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const struct clk_ops clk_multiplier_ops = {
.recalc_rate = clk_multiplier_recalc_rate,
.round_rate = clk_multiplier_round_rate,
.set_rate = clk_multiplier_set_rate,
};
EXPORT_SYMBOL_GPL(clk_multiplier_ops);
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