143 lines
3.6 KiB
C
143 lines
3.6 KiB
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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
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);
|