cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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clk-multiplier.c (3930B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Copyright (C) 2015 Maxime Ripard <maxime.ripard@free-electrons.com>
      4 */
      5
      6#include <linux/bitops.h>
      7#include <linux/clk-provider.h>
      8#include <linux/err.h>
      9#include <linux/export.h>
     10#include <linux/io.h>
     11#include <linux/kernel.h>
     12#include <linux/of.h>
     13#include <linux/slab.h>
     14
     15static inline u32 clk_mult_readl(struct clk_multiplier *mult)
     16{
     17	if (mult->flags & CLK_MULTIPLIER_BIG_ENDIAN)
     18		return ioread32be(mult->reg);
     19
     20	return readl(mult->reg);
     21}
     22
     23static inline void clk_mult_writel(struct clk_multiplier *mult, u32 val)
     24{
     25	if (mult->flags & CLK_MULTIPLIER_BIG_ENDIAN)
     26		iowrite32be(val, mult->reg);
     27	else
     28		writel(val, mult->reg);
     29}
     30
     31static unsigned long __get_mult(struct clk_multiplier *mult,
     32				unsigned long rate,
     33				unsigned long parent_rate)
     34{
     35	if (mult->flags & CLK_MULTIPLIER_ROUND_CLOSEST)
     36		return DIV_ROUND_CLOSEST(rate, parent_rate);
     37
     38	return rate / parent_rate;
     39}
     40
     41static unsigned long clk_multiplier_recalc_rate(struct clk_hw *hw,
     42						unsigned long parent_rate)
     43{
     44	struct clk_multiplier *mult = to_clk_multiplier(hw);
     45	unsigned long val;
     46
     47	val = clk_mult_readl(mult) >> mult->shift;
     48	val &= GENMASK(mult->width - 1, 0);
     49
     50	if (!val && mult->flags & CLK_MULTIPLIER_ZERO_BYPASS)
     51		val = 1;
     52
     53	return parent_rate * val;
     54}
     55
     56static bool __is_best_rate(unsigned long rate, unsigned long new,
     57			   unsigned long best, unsigned long flags)
     58{
     59	if (flags & CLK_MULTIPLIER_ROUND_CLOSEST)
     60		return abs(rate - new) < abs(rate - best);
     61
     62	return new >= rate && new < best;
     63}
     64
     65static unsigned long __bestmult(struct clk_hw *hw, unsigned long rate,
     66				unsigned long *best_parent_rate,
     67				u8 width, unsigned long flags)
     68{
     69	struct clk_multiplier *mult = to_clk_multiplier(hw);
     70	unsigned long orig_parent_rate = *best_parent_rate;
     71	unsigned long parent_rate, current_rate, best_rate = ~0;
     72	unsigned int i, bestmult = 0;
     73	unsigned int maxmult = (1 << width) - 1;
     74
     75	if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
     76		bestmult = rate / orig_parent_rate;
     77
     78		/* Make sure we don't end up with a 0 multiplier */
     79		if ((bestmult == 0) &&
     80		    !(mult->flags & CLK_MULTIPLIER_ZERO_BYPASS))
     81			bestmult = 1;
     82
     83		/* Make sure we don't overflow the multiplier */
     84		if (bestmult > maxmult)
     85			bestmult = maxmult;
     86
     87		return bestmult;
     88	}
     89
     90	for (i = 1; i < maxmult; i++) {
     91		if (rate == orig_parent_rate * i) {
     92			/*
     93			 * This is the best case for us if we have a
     94			 * perfect match without changing the parent
     95			 * rate.
     96			 */
     97			*best_parent_rate = orig_parent_rate;
     98			return i;
     99		}
    100
    101		parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw),
    102						rate / i);
    103		current_rate = parent_rate * i;
    104
    105		if (__is_best_rate(rate, current_rate, best_rate, flags)) {
    106			bestmult = i;
    107			best_rate = current_rate;
    108			*best_parent_rate = parent_rate;
    109		}
    110	}
    111
    112	return bestmult;
    113}
    114
    115static long clk_multiplier_round_rate(struct clk_hw *hw, unsigned long rate,
    116				  unsigned long *parent_rate)
    117{
    118	struct clk_multiplier *mult = to_clk_multiplier(hw);
    119	unsigned long factor = __bestmult(hw, rate, parent_rate,
    120					  mult->width, mult->flags);
    121
    122	return *parent_rate * factor;
    123}
    124
    125static int clk_multiplier_set_rate(struct clk_hw *hw, unsigned long rate,
    126			       unsigned long parent_rate)
    127{
    128	struct clk_multiplier *mult = to_clk_multiplier(hw);
    129	unsigned long factor = __get_mult(mult, rate, parent_rate);
    130	unsigned long flags = 0;
    131	unsigned long val;
    132
    133	if (mult->lock)
    134		spin_lock_irqsave(mult->lock, flags);
    135	else
    136		__acquire(mult->lock);
    137
    138	val = clk_mult_readl(mult);
    139	val &= ~GENMASK(mult->width + mult->shift - 1, mult->shift);
    140	val |= factor << mult->shift;
    141	clk_mult_writel(mult, val);
    142
    143	if (mult->lock)
    144		spin_unlock_irqrestore(mult->lock, flags);
    145	else
    146		__release(mult->lock);
    147
    148	return 0;
    149}
    150
    151const struct clk_ops clk_multiplier_ops = {
    152	.recalc_rate	= clk_multiplier_recalc_rate,
    153	.round_rate	= clk_multiplier_round_rate,
    154	.set_rate	= clk_multiplier_set_rate,
    155};
    156EXPORT_SYMBOL_GPL(clk_multiplier_ops);