diff options
Diffstat (limited to 'drivers/clk/clk-divider.c')
| -rw-r--r-- | drivers/clk/clk-divider.c | 524 |
1 files changed, 524 insertions, 0 deletions
diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c new file mode 100644 index 000000000..25006a8bb --- /dev/null +++ b/drivers/clk/clk-divider.c @@ -0,0 +1,524 @@ +/* + * 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 = DIV_ROUND_UP(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) +{ + unsigned int maxdiv = 0; + const struct clk_div_table *clkt; + + for (clkt = table; clkt->div; clkt++) + if (clkt->div > maxdiv) + 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); + 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) +{ + if (flags & CLK_DIVIDER_ONE_BASED) + return val; + if (flags & CLK_DIVIDER_POWER_OF_TWO) + return 1 << val; + 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) +{ + if (flags & CLK_DIVIDER_ONE_BASED) + return div; + if (flags & CLK_DIVIDER_POWER_OF_TWO) + return __ffs(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) +{ + unsigned int div; + + div = _get_div(table, val, flags); + if (!div) { + 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); +} + +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(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(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(parent_rate, up); + down_rate = DIV_ROUND_UP(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_get_flags(hw->clk) & 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_round_rate(__clk_get_parent(hw->clk), + rate * i); + now = DIV_ROUND_UP(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_round_rate(__clk_get_parent(hw->clk), 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(*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); + return DIV_ROUND_UP(*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(parent_rate, rate); + + if (!_is_valid_div(table, div, flags)) + return -EINVAL; + + 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; + + 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->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); + + 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(struct clk_divider), GFP_KERNEL); + if (!div) { + pr_err("%s: could not allocate divider clk\n", __func__); + 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); |