kernel_optimize_test/drivers/clk/mmp/clk-frac.c
Chao Xie 5d26c15d3b clk: mmp: try to use closer one when do round rate
The orignal code will use the bigger rate between
"previous rate" and "current rate" when caculate the
rate.
In fact, hardware cares about the closest one.
So choose the closer rate between "previous rate" and
"current rate".

Signed-off-by: Chao Xie <chao.xie@marvell.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
2014-03-26 20:59:27 -07:00

158 lines
3.7 KiB
C

/*
* mmp factor clock operation source file
*
* Copyright (C) 2012 Marvell
* Chao Xie <xiechao.mail@gmail.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/clk-provider.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/err.h>
#include "clk.h"
/*
* It is M/N clock
*
* Fout from synthesizer can be given from two equations:
* numerator/denominator = Fin / (Fout * factor)
*/
#define to_clk_factor(hw) container_of(hw, struct clk_factor, hw)
struct clk_factor {
struct clk_hw hw;
void __iomem *base;
struct clk_factor_masks *masks;
struct clk_factor_tbl *ftbl;
unsigned int ftbl_cnt;
};
static long clk_factor_round_rate(struct clk_hw *hw, unsigned long drate,
unsigned long *prate)
{
struct clk_factor *factor = to_clk_factor(hw);
unsigned long rate = 0, prev_rate;
int i;
for (i = 0; i < factor->ftbl_cnt; i++) {
prev_rate = rate;
rate = (((*prate / 10000) * factor->ftbl[i].den) /
(factor->ftbl[i].num * factor->masks->factor)) * 10000;
if (rate > drate)
break;
}
if ((i == 0) || (i == factor->ftbl_cnt)) {
return rate;
} else {
if ((drate - prev_rate) > (rate - drate))
return rate;
else
return prev_rate;
}
}
static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct clk_factor *factor = to_clk_factor(hw);
struct clk_factor_masks *masks = factor->masks;
unsigned int val, num, den;
val = readl_relaxed(factor->base);
/* calculate numerator */
num = (val >> masks->num_shift) & masks->num_mask;
/* calculate denominator */
den = (val >> masks->den_shift) & masks->den_mask;
if (!den)
return 0;
return (((parent_rate / 10000) * den) /
(num * factor->masks->factor)) * 10000;
}
/* Configures new clock rate*/
static int clk_factor_set_rate(struct clk_hw *hw, unsigned long drate,
unsigned long prate)
{
struct clk_factor *factor = to_clk_factor(hw);
struct clk_factor_masks *masks = factor->masks;
int i;
unsigned long val;
unsigned long prev_rate, rate = 0;
for (i = 0; i < factor->ftbl_cnt; i++) {
prev_rate = rate;
rate = (((prate / 10000) * factor->ftbl[i].den) /
(factor->ftbl[i].num * factor->masks->factor)) * 10000;
if (rate > drate)
break;
}
if (i > 0)
i--;
val = readl_relaxed(factor->base);
val &= ~(masks->num_mask << masks->num_shift);
val |= (factor->ftbl[i].num & masks->num_mask) << masks->num_shift;
val &= ~(masks->den_mask << masks->den_shift);
val |= (factor->ftbl[i].den & masks->den_mask) << masks->den_shift;
writel_relaxed(val, factor->base);
return 0;
}
static struct clk_ops clk_factor_ops = {
.recalc_rate = clk_factor_recalc_rate,
.round_rate = clk_factor_round_rate,
.set_rate = clk_factor_set_rate,
};
struct clk *mmp_clk_register_factor(const char *name, const char *parent_name,
unsigned long flags, void __iomem *base,
struct clk_factor_masks *masks, struct clk_factor_tbl *ftbl,
unsigned int ftbl_cnt)
{
struct clk_factor *factor;
struct clk_init_data init;
struct clk *clk;
if (!masks) {
pr_err("%s: must pass a clk_factor_mask\n", __func__);
return ERR_PTR(-EINVAL);
}
factor = kzalloc(sizeof(*factor), GFP_KERNEL);
if (!factor) {
pr_err("%s: could not allocate factor clk\n", __func__);
return ERR_PTR(-ENOMEM);
}
/* struct clk_aux assignments */
factor->base = base;
factor->masks = masks;
factor->ftbl = ftbl;
factor->ftbl_cnt = ftbl_cnt;
factor->hw.init = &init;
init.name = name;
init.ops = &clk_factor_ops;
init.flags = flags;
init.parent_names = &parent_name;
init.num_parents = 1;
clk = clk_register(NULL, &factor->hw);
if (IS_ERR_OR_NULL(clk))
kfree(factor);
return clk;
}