linux-stable/drivers/clk/clk-divider.c
Stephen Boyd fab88ca788 clk: divider: Cap table divider values to 'width' member
When we use a clk divider with a divider table, we limit the
maximum divider value in divider_get_val() to the
div_mask(width), but when we calculate the divider in
divider_round_rate() we don't consider that the maximum divider
may be limited by the width. Pass the width along to
_get_table_maxdiv() so that we only return the maximum divider
that is valid. This is useful for clocks that want to share the
same divider table while limiting the available dividers to some
subset of the table depending on the width of the bitfield.

Cc: Rajendra Nayak <rnayak@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
2015-11-30 18:24:20 -08:00

533 lines
14 KiB
C

/*
* 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 to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)
#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 = 1; i <= maxdiv; i = _next_div(table, i, flags)) {
if (!_is_valid_div(table, i, flags))
continue;
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);
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;
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);