sh: clkfwk: rate table construction and rounding for SH7785.

This adds support for constructing a rate table by looking at potential
divisors for a specified clock. Each FQRMR clock is given its own table.
Presently each table is rebuilt when the parent propagates down a new
rate, so some more logic needs to be added to do this more intelligently.

Additionally, a fairly generic round_rate() implementation is then
layered on top of it, which subsequently provides us with cpufreq support.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Paul Mundt 2009-05-13 20:28:15 +09:00
parent a77b5ac0ea
commit cc96eace48
3 changed files with 100 additions and 13 deletions

View File

@ -16,6 +16,7 @@ struct clk_ops {
int (*set_rate)(struct clk *clk, unsigned long rate, int algo_id);
int (*set_parent)(struct clk *clk, struct clk *parent);
long (*round_rate)(struct clk *clk, unsigned long rate);
void (*build_rate_table)(struct clk *clk);
};
struct clk {

View File

@ -63,6 +63,9 @@ void propagate_rate(struct clk *tclk)
list_for_each_entry(clkp, &tclk->children, sibling) {
if (clkp->ops && clkp->ops->recalc)
clkp->rate = clkp->ops->recalc(clkp);
if (clkp->ops && clkp->ops->build_rate_table)
clkp->ops->build_rate_table(clkp);
propagate_rate(clkp);
}
}

View File

@ -13,6 +13,7 @@
#include <linux/kernel.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/cpufreq.h>
#include <asm/clock.h>
#include <asm/freq.h>
@ -20,21 +21,35 @@ static unsigned int div2[] = { 1, 2, 4, 6, 8, 12, 16, 18,
24, 32, 36, 48 };
struct clk_priv {
unsigned int shift;
/* allowable divisor bitmap */
unsigned long div_bitmap;
/* Supportable frequencies + termination entry */
struct cpufreq_frequency_table freq_table[ARRAY_SIZE(div2)+1];
};
#define FRQMR_CLK_DATA(_name, _shift) \
static struct clk_priv _name##_data = { .shift = _shift, }
#define FRQMR_CLK_DATA(_name, _shift, _div_bitmap) \
static struct clk_priv _name##_data = { \
.shift = _shift, \
.div_bitmap = _div_bitmap, \
\
.freq_table[0] = { \
.index = 0, \
.frequency = CPUFREQ_TABLE_END, \
}, \
}
FRQMR_CLK_DATA(pfc, 0);
FRQMR_CLK_DATA(s3fc, 4);
FRQMR_CLK_DATA(s2fc, 8);
FRQMR_CLK_DATA(mfc, 12);
FRQMR_CLK_DATA(bfc, 16);
FRQMR_CLK_DATA(sfc, 20);
FRQMR_CLK_DATA(ufc, 24);
FRQMR_CLK_DATA(ifc, 28);
FRQMR_CLK_DATA(pfc, 0, 0x0f80);
FRQMR_CLK_DATA(s3fc, 4, 0x0ff0);
FRQMR_CLK_DATA(s2fc, 8, 0x0030);
FRQMR_CLK_DATA(mfc, 12, 0x000c);
FRQMR_CLK_DATA(bfc, 16, 0x0fe0);
FRQMR_CLK_DATA(sfc, 20, 0x000c);
FRQMR_CLK_DATA(ufc, 24, 0x000c);
FRQMR_CLK_DATA(ifc, 28, 0x000e);
static unsigned long frqmr_clk_recalc(struct clk *clk)
static unsigned long frqmr_recalc(struct clk *clk)
{
struct clk_priv *data = clk->priv;
unsigned int idx;
@ -49,8 +64,76 @@ static unsigned long frqmr_clk_recalc(struct clk *clk)
return clk->parent->rate * 36 / div2[idx];
}
static void frqmr_build_rate_table(struct clk *clk)
{
struct clk_priv *data = clk->priv;
int i, entry;
for (i = entry = 0; i < ARRAY_SIZE(div2); i++) {
if ((data->div_bitmap & (1 << i)) == 0)
continue;
data->freq_table[entry].index = entry;
data->freq_table[entry].frequency =
clk->parent->rate * 36 / div2[i];
entry++;
}
if (entry == 0) {
pr_warning("clkfwk: failed to build frequency table "
"for \"%s\" clk!\n", clk->name);
return;
}
/* Termination entry */
data->freq_table[entry].index = entry;
data->freq_table[entry].frequency = CPUFREQ_TABLE_END;
}
static long frqmr_round_rate(struct clk *clk, unsigned long rate)
{
struct clk_priv *data = clk->priv;
unsigned long rate_error, rate_error_prev = ~0UL;
unsigned long rate_best_fit = rate;
unsigned long highest, lowest;
int i;
highest = lowest = 0;
for (i = 0; data->freq_table[i].frequency != CPUFREQ_TABLE_END; i++) {
unsigned long freq = data->freq_table[i].frequency;
if (freq == CPUFREQ_ENTRY_INVALID)
continue;
if (freq > highest)
highest = freq;
if (freq < lowest)
lowest = freq;
rate_error = abs(freq - rate);
if (rate_error < rate_error_prev) {
rate_best_fit = freq;
rate_error_prev = rate_error;
}
if (rate_error == 0)
break;
}
if (rate >= highest)
rate_best_fit = highest;
if (rate <= lowest)
rate_best_fit = lowest;
return rate_best_fit;
}
static struct clk_ops frqmr_clk_ops = {
.recalc = frqmr_clk_recalc,
.recalc = frqmr_recalc,
.build_rate_table = frqmr_build_rate_table,
.round_rate = frqmr_round_rate,
};
/*