Skip to content
Fetching contributors…
Cannot retrieve contributors at this time
540 lines (452 sloc) 13.9 KB
/*
* Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
* Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
* Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
*
* 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.
*
* Adjustable divider clock implementation
*/
#include <linux/clk-provider.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/string.h>
#include <linux/log2.h>
/*
* DOC: basic adjustable divider clock that cannot gate
*
* Traits of this clock:
* prepare - clk_prepare only ensures that parents are prepared
* enable - clk_enable only ensures that parents are enabled
* rate - rate is adjustable. clk->rate = ceiling(parent->rate / divisor)
* parent - fixed parent. No clk_set_parent support
*/
#define div_mask(width) ((1 << (width)) - 1)
static unsigned int _get_table_maxdiv(const struct clk_div_table *table,
u8 width)
{
unsigned int maxdiv = 0, mask = div_mask(width);
const struct clk_div_table *clkt;
for (clkt = table; clkt->div; clkt++)
if (clkt->div > maxdiv && clkt->val <= mask)
maxdiv = clkt->div;
return maxdiv;
}
static unsigned int _get_table_mindiv(const struct clk_div_table *table)
{
unsigned int mindiv = UINT_MAX;
const struct clk_div_table *clkt;
for (clkt = table; clkt->div; clkt++)
if (clkt->div < mindiv)
mindiv = clkt->div;
return mindiv;
}
static unsigned int _get_maxdiv(const struct clk_div_table *table, u8 width,
unsigned long flags)
{
if (flags & CLK_DIVIDER_ONE_BASED)
return div_mask(width);
if (flags & CLK_DIVIDER_POWER_OF_TWO)
return 1 << div_mask(width);
if (table)
return _get_table_maxdiv(table, width);
return div_mask(width) + 1;
}
static unsigned int _get_table_div(const struct clk_div_table *table,
unsigned int val)
{
const struct clk_div_table *clkt;
for (clkt = table; clkt->div; clkt++)
if (clkt->val == val)
return clkt->div;
return 0;
}
static unsigned int _get_div(const struct clk_div_table *table,
unsigned int val, unsigned long flags, u8 width)
{
if (flags & CLK_DIVIDER_ONE_BASED)
return val;
if (flags & CLK_DIVIDER_POWER_OF_TWO)
return 1 << val;
if (flags & CLK_DIVIDER_MAX_AT_ZERO)
return val ? val : div_mask(width) + 1;
if (table)
return _get_table_div(table, val);
return val + 1;
}
static unsigned int _get_table_val(const struct clk_div_table *table,
unsigned int div)
{
const struct clk_div_table *clkt;
for (clkt = table; clkt->div; clkt++)
if (clkt->div == div)
return clkt->val;
return 0;
}
static unsigned int _get_val(const struct clk_div_table *table,
unsigned int div, unsigned long flags, u8 width)
{
if (flags & CLK_DIVIDER_ONE_BASED)
return div;
if (flags & CLK_DIVIDER_POWER_OF_TWO)
return __ffs(div);
if (flags & CLK_DIVIDER_MAX_AT_ZERO)
return (div == div_mask(width) + 1) ? 0 : div;
if (table)
return _get_table_val(table, div);
return div - 1;
}
unsigned long divider_recalc_rate(struct clk_hw *hw, unsigned long parent_rate,
unsigned int val,
const struct clk_div_table *table,
unsigned long flags)
{
struct clk_divider *divider = to_clk_divider(hw);
unsigned int div;
div = _get_div(table, val, flags, divider->width);
if (!div) {
WARN(!(flags & CLK_DIVIDER_ALLOW_ZERO),
"%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
clk_hw_get_name(hw));
return parent_rate;
}
return DIV_ROUND_UP_ULL((u64)parent_rate, div);
}
EXPORT_SYMBOL_GPL(divider_recalc_rate);
static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct clk_divider *divider = to_clk_divider(hw);
unsigned int val;
val = clk_readl(divider->reg) >> divider->shift;
val &= div_mask(divider->width);
return divider_recalc_rate(hw, parent_rate, val, divider->table,
divider->flags);
}
static bool _is_valid_table_div(const struct clk_div_table *table,
unsigned int div)
{
const struct clk_div_table *clkt;
for (clkt = table; clkt->div; clkt++)
if (clkt->div == div)
return true;
return false;
}
static bool _is_valid_div(const struct clk_div_table *table, unsigned int div,
unsigned long flags)
{
if (flags & CLK_DIVIDER_POWER_OF_TWO)
return is_power_of_2(div);
if (table)
return _is_valid_table_div(table, div);
return true;
}
static int _round_up_table(const struct clk_div_table *table, int div)
{
const struct clk_div_table *clkt;
int up = INT_MAX;
for (clkt = table; clkt->div; clkt++) {
if (clkt->div == div)
return clkt->div;
else if (clkt->div < div)
continue;
if ((clkt->div - div) < (up - div))
up = clkt->div;
}
return up;
}
static int _round_down_table(const struct clk_div_table *table, int div)
{
const struct clk_div_table *clkt;
int down = _get_table_mindiv(table);
for (clkt = table; clkt->div; clkt++) {
if (clkt->div == div)
return clkt->div;
else if (clkt->div > div)
continue;
if ((div - clkt->div) < (div - down))
down = clkt->div;
}
return down;
}
static int _div_round_up(const struct clk_div_table *table,
unsigned long parent_rate, unsigned long rate,
unsigned long flags)
{
int div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
if (flags & CLK_DIVIDER_POWER_OF_TWO)
div = __roundup_pow_of_two(div);
if (table)
div = _round_up_table(table, div);
return div;
}
static int _div_round_closest(const struct clk_div_table *table,
unsigned long parent_rate, unsigned long rate,
unsigned long flags)
{
int up, down;
unsigned long up_rate, down_rate;
up = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
down = parent_rate / rate;
if (flags & CLK_DIVIDER_POWER_OF_TWO) {
up = __roundup_pow_of_two(up);
down = __rounddown_pow_of_two(down);
} else if (table) {
up = _round_up_table(table, up);
down = _round_down_table(table, down);
}
up_rate = DIV_ROUND_UP_ULL((u64)parent_rate, up);
down_rate = DIV_ROUND_UP_ULL((u64)parent_rate, down);
return (rate - up_rate) <= (down_rate - rate) ? up : down;
}
static int _div_round(const struct clk_div_table *table,
unsigned long parent_rate, unsigned long rate,
unsigned long flags)
{
if (flags & CLK_DIVIDER_ROUND_CLOSEST)
return _div_round_closest(table, parent_rate, rate, flags);
return _div_round_up(table, parent_rate, rate, flags);
}
static bool _is_best_div(unsigned long rate, unsigned long now,
unsigned long best, unsigned long flags)
{
if (flags & CLK_DIVIDER_ROUND_CLOSEST)
return abs(rate - now) < abs(rate - best);
return now <= rate && now > best;
}
static int _next_div(const struct clk_div_table *table, int div,
unsigned long flags)
{
div++;
if (flags & CLK_DIVIDER_POWER_OF_TWO)
return __roundup_pow_of_two(div);
if (table)
return _round_up_table(table, div);
return div;
}
static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
unsigned long *best_parent_rate,
const struct clk_div_table *table, u8 width,
unsigned long flags)
{
int i, bestdiv = 0;
unsigned long parent_rate, best = 0, now, maxdiv;
unsigned long parent_rate_saved = *best_parent_rate;
if (!rate)
rate = 1;
maxdiv = _get_maxdiv(table, width, flags);
if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
parent_rate = *best_parent_rate;
bestdiv = _div_round(table, parent_rate, rate, flags);
bestdiv = bestdiv == 0 ? 1 : bestdiv;
bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
return bestdiv;
}
/*
* The maximum divider we can use without overflowing
* unsigned long in rate * i below
*/
maxdiv = min(ULONG_MAX / rate, maxdiv);
for (i = _next_div(table, 0, flags); i <= maxdiv;
i = _next_div(table, i, flags)) {
if (rate * i == parent_rate_saved) {
/*
* It's the most ideal case if the requested rate can be
* divided from parent clock without needing to change
* parent rate, so return the divider immediately.
*/
*best_parent_rate = parent_rate_saved;
return i;
}
parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw),
rate * i);
now = DIV_ROUND_UP_ULL((u64)parent_rate, i);
if (_is_best_div(rate, now, best, flags)) {
bestdiv = i;
best = now;
*best_parent_rate = parent_rate;
}
}
if (!bestdiv) {
bestdiv = _get_maxdiv(table, width, flags);
*best_parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw), 1);
}
return bestdiv;
}
long divider_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *prate, const struct clk_div_table *table,
u8 width, unsigned long flags)
{
int div;
div = clk_divider_bestdiv(hw, rate, prate, table, width, flags);
return DIV_ROUND_UP_ULL((u64)*prate, div);
}
EXPORT_SYMBOL_GPL(divider_round_rate);
static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *prate)
{
struct clk_divider *divider = to_clk_divider(hw);
int bestdiv;
/* if read only, just return current value */
if (divider->flags & CLK_DIVIDER_READ_ONLY) {
bestdiv = readl(divider->reg) >> divider->shift;
bestdiv &= div_mask(divider->width);
bestdiv = _get_div(divider->table, bestdiv, divider->flags,
divider->width);
return DIV_ROUND_UP_ULL((u64)*prate, bestdiv);
}
return divider_round_rate(hw, rate, prate, divider->table,
divider->width, divider->flags);
}
int divider_get_val(unsigned long rate, unsigned long parent_rate,
const struct clk_div_table *table, u8 width,
unsigned long flags)
{
unsigned int div, value;
div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
if (!_is_valid_div(table, div, flags))
return -EINVAL;
value = _get_val(table, div, flags, width);
return min_t(unsigned int, value, div_mask(width));
}
EXPORT_SYMBOL_GPL(divider_get_val);
static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct clk_divider *divider = to_clk_divider(hw);
unsigned int value;
unsigned long flags = 0;
u32 val;
value = divider_get_val(rate, parent_rate, divider->table,
divider->width, divider->flags);
if (divider->lock)
spin_lock_irqsave(divider->lock, flags);
else
__acquire(divider->lock);
if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
val = div_mask(divider->width) << (divider->shift + 16);
} else {
val = clk_readl(divider->reg);
val &= ~(div_mask(divider->width) << divider->shift);
}
val |= value << divider->shift;
clk_writel(val, divider->reg);
if (divider->lock)
spin_unlock_irqrestore(divider->lock, flags);
else
__release(divider->lock);
return 0;
}
const struct clk_ops clk_divider_ops = {
.recalc_rate = clk_divider_recalc_rate,
.round_rate = clk_divider_round_rate,
.set_rate = clk_divider_set_rate,
};
EXPORT_SYMBOL_GPL(clk_divider_ops);
const struct clk_ops clk_divider_ro_ops = {
.recalc_rate = clk_divider_recalc_rate,
.round_rate = clk_divider_round_rate,
};
EXPORT_SYMBOL_GPL(clk_divider_ro_ops);
static struct clk *_register_divider(struct device *dev, const char *name,
const char *parent_name, unsigned long flags,
void __iomem *reg, u8 shift, u8 width,
u8 clk_divider_flags, const struct clk_div_table *table,
spinlock_t *lock)
{
struct clk_divider *div;
struct clk *clk;
struct clk_init_data init;
if (clk_divider_flags & CLK_DIVIDER_HIWORD_MASK) {
if (width + shift > 16) {
pr_warn("divider value exceeds LOWORD field\n");
return ERR_PTR(-EINVAL);
}
}
/* allocate the divider */
div = kzalloc(sizeof(*div), GFP_KERNEL);
if (!div)
return ERR_PTR(-ENOMEM);
init.name = name;
if (clk_divider_flags & CLK_DIVIDER_READ_ONLY)
init.ops = &clk_divider_ro_ops;
else
init.ops = &clk_divider_ops;
init.flags = flags | CLK_IS_BASIC;
init.parent_names = (parent_name ? &parent_name: NULL);
init.num_parents = (parent_name ? 1 : 0);
/* struct clk_divider assignments */
div->reg = reg;
div->shift = shift;
div->width = width;
div->flags = clk_divider_flags;
div->lock = lock;
div->hw.init = &init;
div->table = table;
/* register the clock */
clk = clk_register(dev, &div->hw);
if (IS_ERR(clk))
kfree(div);
return clk;
}
/**
* clk_register_divider - register a divider clock with the clock framework
* @dev: device registering this clock
* @name: name of this clock
* @parent_name: name of clock's parent
* @flags: framework-specific flags
* @reg: register address to adjust divider
* @shift: number of bits to shift the bitfield
* @width: width of the bitfield
* @clk_divider_flags: divider-specific flags for this clock
* @lock: shared register lock for this clock
*/
struct clk *clk_register_divider(struct device *dev, const char *name,
const char *parent_name, unsigned long flags,
void __iomem *reg, u8 shift, u8 width,
u8 clk_divider_flags, spinlock_t *lock)
{
return _register_divider(dev, name, parent_name, flags, reg, shift,
width, clk_divider_flags, NULL, lock);
}
EXPORT_SYMBOL_GPL(clk_register_divider);
/**
* clk_register_divider_table - register a table based divider clock with
* the clock framework
* @dev: device registering this clock
* @name: name of this clock
* @parent_name: name of clock's parent
* @flags: framework-specific flags
* @reg: register address to adjust divider
* @shift: number of bits to shift the bitfield
* @width: width of the bitfield
* @clk_divider_flags: divider-specific flags for this clock
* @table: array of divider/value pairs ending with a div set to 0
* @lock: shared register lock for this clock
*/
struct clk *clk_register_divider_table(struct device *dev, const char *name,
const char *parent_name, unsigned long flags,
void __iomem *reg, u8 shift, u8 width,
u8 clk_divider_flags, const struct clk_div_table *table,
spinlock_t *lock)
{
return _register_divider(dev, name, parent_name, flags, reg, shift,
width, clk_divider_flags, table, lock);
}
EXPORT_SYMBOL_GPL(clk_register_divider_table);
void clk_unregister_divider(struct clk *clk)
{
struct clk_divider *div;
struct clk_hw *hw;
hw = __clk_get_hw(clk);
if (!hw)
return;
div = to_clk_divider(hw);
clk_unregister(clk);
kfree(div);
}
EXPORT_SYMBOL_GPL(clk_unregister_divider);
Something went wrong with that request. Please try again.