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clk: divider: Make generic for usage elsewhere
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Some devices don't use mmio to interact with dividers. Split out the
logic from the register read/write parts so that we can reuse the
division logic elsewhere.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Tested-by: Kenneth Westfield <kwestfie@codeaurora.org>
Signed-off-by: Michael Turquette <mturquette@linaro.org>
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Stephen Boyd authored and Michael Turquette committed Jan 27, 2015
1 parent 15a02c1 commit bca9690
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Showing 2 changed files with 139 additions and 84 deletions.
212 changes: 128 additions & 84 deletions drivers/clk/clk-divider.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@

#define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)

#define div_mask(d) ((1 << ((d)->width)) - 1)
#define div_mask(width) ((1 << (width)) - 1)

static unsigned int _get_table_maxdiv(const struct clk_div_table *table)
{
Expand All @@ -54,15 +54,16 @@ static unsigned int _get_table_mindiv(const struct clk_div_table *table)
return mindiv;
}

static unsigned int _get_maxdiv(struct clk_divider *divider)
static unsigned int _get_maxdiv(const struct clk_div_table *table, u8 width,
unsigned long flags)
{
if (divider->flags & CLK_DIVIDER_ONE_BASED)
return div_mask(divider);
if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
return 1 << div_mask(divider);
if (divider->table)
return _get_table_maxdiv(divider->table);
return div_mask(divider) + 1;
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);
return div_mask(width) + 1;
}

static unsigned int _get_table_div(const struct clk_div_table *table,
Expand All @@ -76,14 +77,15 @@ static unsigned int _get_table_div(const struct clk_div_table *table,
return 0;
}

static unsigned int _get_div(struct clk_divider *divider, unsigned int val)
static unsigned int _get_div(const struct clk_div_table *table,
unsigned int val, unsigned long flags)
{
if (divider->flags & CLK_DIVIDER_ONE_BASED)
if (flags & CLK_DIVIDER_ONE_BASED)
return val;
if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
if (flags & CLK_DIVIDER_POWER_OF_TWO)
return 1 << val;
if (divider->table)
return _get_table_div(divider->table, val);
if (table)
return _get_table_div(table, val);
return val + 1;
}

Expand All @@ -98,36 +100,49 @@ static unsigned int _get_table_val(const struct clk_div_table *table,
return 0;
}

static unsigned int _get_val(struct clk_divider *divider, unsigned int div)
static unsigned int _get_val(const struct clk_div_table *table,
unsigned int div, unsigned long flags)
{
if (divider->flags & CLK_DIVIDER_ONE_BASED)
if (flags & CLK_DIVIDER_ONE_BASED)
return div;
if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
if (flags & CLK_DIVIDER_POWER_OF_TWO)
return __ffs(div);
if (divider->table)
return _get_table_val(divider->table, div);
if (table)
return _get_table_val(table, div);
return div - 1;
}

static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
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, val;
unsigned int div;

val = clk_readl(divider->reg) >> divider->shift;
val &= div_mask(divider);

div = _get_div(divider, val);
div = _get_div(table, val, flags);
if (!div) {
WARN(!(divider->flags & CLK_DIVIDER_ALLOW_ZERO),
WARN(!(flags & CLK_DIVIDER_ALLOW_ZERO),
"%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
__clk_get_name(hw->clk));
return parent_rate;
}

return DIV_ROUND_UP(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);
}

/*
* The reverse of DIV_ROUND_UP: The maximum number which
Expand All @@ -146,12 +161,13 @@ static bool _is_valid_table_div(const struct clk_div_table *table,
return false;
}

static bool _is_valid_div(struct clk_divider *divider, unsigned int div)
static bool _is_valid_div(const struct clk_div_table *table, unsigned int div,
unsigned long flags)
{
if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
if (flags & CLK_DIVIDER_POWER_OF_TWO)
return is_power_of_2(div);
if (divider->table)
return _is_valid_table_div(divider->table, div);
if (table)
return _is_valid_table_div(table, div);
return true;
}

Expand Down Expand Up @@ -191,91 +207,88 @@ static int _round_down_table(const struct clk_div_table *table, int div)
return down;
}

static int _div_round_up(struct clk_divider *divider,
unsigned long parent_rate, unsigned long rate)
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(parent_rate, rate);

if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
if (flags & CLK_DIVIDER_POWER_OF_TWO)
div = __roundup_pow_of_two(div);
if (divider->table)
div = _round_up_table(divider->table, div);
if (table)
div = _round_up_table(table, div);

return div;
}

static int _div_round_closest(struct clk_divider *divider,
unsigned long parent_rate, unsigned long rate)
static int _div_round_closest(const struct clk_div_table *table,
unsigned long parent_rate, unsigned long rate,
unsigned long flags)
{
int up, down, div;

up = down = div = DIV_ROUND_CLOSEST(parent_rate, rate);

if (divider->flags & CLK_DIVIDER_POWER_OF_TWO) {
if (flags & CLK_DIVIDER_POWER_OF_TWO) {
up = __roundup_pow_of_two(div);
down = __rounddown_pow_of_two(div);
} else if (divider->table) {
up = _round_up_table(divider->table, div);
down = _round_down_table(divider->table, div);
} else if (table) {
up = _round_up_table(table, div);
down = _round_down_table(table, div);
}

return (up - div) <= (div - down) ? up : down;
}

static int _div_round(struct clk_divider *divider, unsigned long parent_rate,
unsigned long rate)
static int _div_round(const struct clk_div_table *table,
unsigned long parent_rate, unsigned long rate,
unsigned long flags)
{
if (divider->flags & CLK_DIVIDER_ROUND_CLOSEST)
return _div_round_closest(divider, parent_rate, rate);
if (flags & CLK_DIVIDER_ROUND_CLOSEST)
return _div_round_closest(table, parent_rate, rate, flags);

return _div_round_up(divider, parent_rate, rate);
return _div_round_up(table, parent_rate, rate, flags);
}

static bool _is_best_div(struct clk_divider *divider,
unsigned long rate, unsigned long now, unsigned long best)
static bool _is_best_div(unsigned long rate, unsigned long now,
unsigned long best, unsigned long flags)
{
if (divider->flags & CLK_DIVIDER_ROUND_CLOSEST)
if (flags & CLK_DIVIDER_ROUND_CLOSEST)
return abs(rate - now) < abs(rate - best);

return now <= rate && now > best;
}

static int _next_div(struct clk_divider *divider, int div)
static int _next_div(const struct clk_div_table *table, int div,
unsigned long flags)
{
div++;

if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
if (flags & CLK_DIVIDER_POWER_OF_TWO)
return __roundup_pow_of_two(div);
if (divider->table)
return _round_up_table(divider->table, 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)
unsigned long *best_parent_rate,
const struct clk_div_table *table, u8 width,
unsigned long flags)
{
struct clk_divider *divider = to_clk_divider(hw);
int i, bestdiv = 0;
unsigned long parent_rate, best = 0, now, maxdiv;
unsigned long parent_rate_saved = *best_parent_rate;

if (!rate)
rate = 1;

/* if read only, just return current value */
if (divider->flags & CLK_DIVIDER_READ_ONLY) {
bestdiv = readl(divider->reg) >> divider->shift;
bestdiv &= div_mask(divider);
bestdiv = _get_div(divider, bestdiv);
return bestdiv;
}

maxdiv = _get_maxdiv(divider);
maxdiv = _get_maxdiv(table, width, flags);

if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
parent_rate = *best_parent_rate;
bestdiv = _div_round(divider, parent_rate, rate);
bestdiv = _div_round(table, parent_rate, rate, flags);
bestdiv = bestdiv == 0 ? 1 : bestdiv;
bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
return bestdiv;
Expand All @@ -287,8 +300,8 @@ static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
*/
maxdiv = min(ULONG_MAX / rate, maxdiv);

for (i = 1; i <= maxdiv; i = _next_div(divider, i)) {
if (!_is_valid_div(divider, i))
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) {
/*
Expand All @@ -302,56 +315,87 @@ static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
parent_rate = __clk_round_rate(__clk_get_parent(hw->clk),
MULT_ROUND_UP(rate, i));
now = DIV_ROUND_UP(parent_rate, i);
if (_is_best_div(divider, rate, now, best)) {
if (_is_best_div(rate, now, best, flags)) {
bestdiv = i;
best = now;
*best_parent_rate = parent_rate;
}
}

if (!bestdiv) {
bestdiv = _get_maxdiv(divider);
bestdiv = _get_maxdiv(table, width, flags);
*best_parent_rate = __clk_round_rate(__clk_get_parent(hw->clk), 1);
}

return bestdiv;
}

static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *prate)
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);

div = clk_divider_bestdiv(hw, rate, prate, table, width, flags);

return DIV_ROUND_UP(*prate, div);
}
EXPORT_SYMBOL_GPL(divider_round_rate);

static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_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);
return 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;
unsigned long flags = 0;
u32 val;

div = DIV_ROUND_UP(parent_rate, rate);

if (!_is_valid_div(divider, div))
if (!_is_valid_div(table, div, flags))
return -EINVAL;

value = _get_val(divider, div);
value = _get_val(table, div, flags);

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;

if (value > div_mask(divider))
value = div_mask(divider);
value = divider_get_val(rate, parent_rate, divider->table,
divider->width, divider->flags);

if (divider->lock)
spin_lock_irqsave(divider->lock, flags);

if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
val = div_mask(divider) << (divider->shift + 16);
val = div_mask(divider->width) << (divider->shift + 16);
} else {
val = clk_readl(divider->reg);
val &= ~(div_mask(divider) << divider->shift);
val &= ~(div_mask(divider->width) << divider->shift);
}
val |= value << divider->shift;
clk_writel(val, divider->reg);
Expand Down
11 changes: 11 additions & 0 deletions include/linux/clk-provider.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -353,6 +353,17 @@ struct clk_divider {
#define CLK_DIVIDER_READ_ONLY BIT(5)

extern const struct clk_ops clk_divider_ops;

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);
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 divider_get_val(unsigned long rate, unsigned long parent_rate,
const struct clk_div_table *table, u8 width,
unsigned long flags);

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,
Expand Down

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