diff options
Diffstat (limited to 'drivers/clk/clk-divider.c')
| -rw-r--r-- | drivers/clk/clk-divider.c | 176 |
1 files changed, 160 insertions, 16 deletions
diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c index 68b40210117..18a9de29df0 100644 --- a/drivers/clk/clk-divider.c +++ b/drivers/clk/clk-divider.c @@ -24,7 +24,7 @@ * 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 = parent->rate / divisor + * rate - rate is adjustable. clk->rate = DIV_ROUND_UP(parent->rate / divisor) * parent - fixed parent. No clk_set_parent support */ @@ -43,6 +43,17 @@ static unsigned int _get_table_maxdiv(const struct clk_div_table *table) 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(struct clk_divider *divider) { if (divider->flags & CLK_DIVIDER_ONE_BASED) @@ -87,7 +98,7 @@ static unsigned int _get_table_val(const struct clk_div_table *table, return 0; } -static unsigned int _get_val(struct clk_divider *divider, u8 div) +static unsigned int _get_val(struct clk_divider *divider, unsigned int div) { if (divider->flags & CLK_DIVIDER_ONE_BASED) return div; @@ -104,17 +115,18 @@ static unsigned long clk_divider_recalc_rate(struct clk_hw *hw, struct clk_divider *divider = to_clk_divider(hw); unsigned int div, val; - val = readl(divider->reg) >> divider->shift; + val = clk_readl(divider->reg) >> divider->shift; val &= div_mask(divider); div = _get_div(divider, val); if (!div) { - WARN(1, "%s: Invalid divisor for clock %s\n", __func__, - __clk_get_name(hw->clk)); + WARN(!(divider->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 parent_rate / div; + return DIV_ROUND_UP(parent_rate, div); } /* @@ -143,12 +155,110 @@ static bool _is_valid_div(struct clk_divider *divider, unsigned int 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(struct clk_divider *divider, + unsigned long parent_rate, unsigned long rate) +{ + int div = DIV_ROUND_UP(parent_rate, rate); + + if (divider->flags & CLK_DIVIDER_POWER_OF_TWO) + div = __roundup_pow_of_two(div); + if (divider->table) + div = _round_up_table(divider->table, div); + + return div; +} + +static int _div_round_closest(struct clk_divider *divider, + unsigned long parent_rate, unsigned long rate) +{ + int up, down, div; + + up = down = div = DIV_ROUND_CLOSEST(parent_rate, rate); + + if (divider->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); + } + + return (up - div) <= (div - down) ? up : down; +} + +static int _div_round(struct clk_divider *divider, unsigned long parent_rate, + unsigned long rate) +{ + if (divider->flags & CLK_DIVIDER_ROUND_CLOSEST) + return _div_round_closest(divider, parent_rate, rate); + + return _div_round_up(divider, parent_rate, rate); +} + +static bool _is_best_div(struct clk_divider *divider, + unsigned long rate, unsigned long now, unsigned long best) +{ + if (divider->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) +{ + div++; + + if (divider->flags & CLK_DIVIDER_POWER_OF_TWO) + return __roundup_pow_of_two(div); + if (divider->table) + return _round_up_table(divider->table, div); + + return div; +} + static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate, unsigned long *best_parent_rate) { 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; @@ -157,7 +267,7 @@ static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate, if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) { parent_rate = *best_parent_rate; - bestdiv = DIV_ROUND_UP(parent_rate, rate); + bestdiv = _div_round(divider, parent_rate, rate); bestdiv = bestdiv == 0 ? 1 : bestdiv; bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv; return bestdiv; @@ -169,13 +279,22 @@ static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate, */ maxdiv = min(ULONG_MAX / rate, maxdiv); - for (i = 1; i <= maxdiv; i++) { + for (i = 1; i <= maxdiv; i = _next_div(divider, i)) { if (!_is_valid_div(divider, i)) 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_round_rate(__clk_get_parent(hw->clk), MULT_ROUND_UP(rate, i)); - now = parent_rate / i; - if (now <= rate && now > best) { + now = DIV_ROUND_UP(parent_rate, i); + if (_is_best_div(divider, rate, now, best)) { bestdiv = i; best = now; *best_parent_rate = parent_rate; @@ -196,7 +315,7 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate, int div; div = clk_divider_bestdiv(hw, rate, prate); - return *prate / div; + return DIV_ROUND_UP(*prate, div); } static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate, @@ -207,7 +326,11 @@ static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate, unsigned long flags = 0; u32 val; - div = parent_rate / rate; + div = DIV_ROUND_UP(parent_rate, rate); + + if (!_is_valid_div(divider, div)) + return -EINVAL; + value = _get_val(divider, div); if (value > div_mask(divider)) @@ -216,10 +339,14 @@ static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate, if (divider->lock) spin_lock_irqsave(divider->lock, flags); - val = readl(divider->reg); - val &= ~(div_mask(divider) << divider->shift); + if (divider->flags & CLK_DIVIDER_HIWORD_MASK) { + val = div_mask(divider) << (divider->shift + 16); + } else { + val = clk_readl(divider->reg); + val &= ~(div_mask(divider) << divider->shift); + } val |= value << divider->shift; - writel(val, divider->reg); + clk_writel(val, divider->reg); if (divider->lock) spin_unlock_irqrestore(divider->lock, flags); @@ -234,6 +361,11 @@ const struct clk_ops clk_divider_ops = { }; EXPORT_SYMBOL_GPL(clk_divider_ops); +const struct clk_ops clk_divider_ro_ops = { + .recalc_rate = clk_divider_recalc_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, @@ -244,6 +376,13 @@ static struct clk *_register_divider(struct device *dev, const char *name, 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(struct clk_divider), GFP_KERNEL); if (!div) { @@ -252,7 +391,10 @@ static struct clk *_register_divider(struct device *dev, const char *name, } init.name = name; - init.ops = &clk_divider_ops; + 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); @@ -295,6 +437,7 @@ struct clk *clk_register_divider(struct device *dev, const char *name, 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 @@ -319,3 +462,4 @@ struct clk *clk_register_divider_table(struct device *dev, const char *name, return _register_divider(dev, name, parent_name, flags, reg, shift, width, clk_divider_flags, table, lock); } +EXPORT_SYMBOL_GPL(clk_register_divider_table); |