1 files changed, 465 insertions, 0 deletions
diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
new file mode 100644
index 00000000000..18a9de29df0
--- /dev/null
+++ b/drivers/clk/clk-divider.c
@@ -0,0 +1,465 @@
+/*
+ * 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(d)	((1 << ((d)->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(struct clk_divider *divider)
+{
+	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;
+}
+
+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(struct clk_divider *divider, unsigned int val)
+{
+	if (divider->flags & CLK_DIVIDER_ONE_BASED)
+		return val;
+	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
+		return 1 << val;
+	if (divider->table)
+		return _get_table_div(divider->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(struct clk_divider *divider, unsigned int div)
+{
+	if (divider->flags & CLK_DIVIDER_ONE_BASED)
+		return div;
+	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
+		return __ffs(div);
+	if (divider->table)
+		return  _get_table_val(divider->table, div);
+	return div - 1;
+}
+
+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 div, val;
+
+	val = clk_readl(divider->reg) >> divider->shift;
+	val &= div_mask(divider);
+
+	div = _get_div(divider, val);
+	if (!div) {
+		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 DIV_ROUND_UP(parent_rate, div);
+}
+
+/*
+ * The reverse of DIV_ROUND_UP: The maximum number which
+ * divided by m is r
+ */
+#define MULT_ROUND_UP(r, m) ((r) * (m) + (m) - 1)
+
+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(struct clk_divider *divider, unsigned int div)
+{
+	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
+		return is_power_of_2(div);
+	if (divider->table)
+		return _is_valid_table_div(divider->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(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;
+
+	maxdiv = _get_maxdiv(divider);
+
+	if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
+		parent_rate = *best_parent_rate;
+		bestdiv = _div_round(divider, parent_rate, rate);
+		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(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 = DIV_ROUND_UP(parent_rate, i);
+		if (_is_best_div(divider, rate, now, best)) {
+			bestdiv = i;
+			best = now;
+			*best_parent_rate = parent_rate;
+		}
+	}
+
+	if (!bestdiv) {
+		bestdiv = _get_maxdiv(divider);
+		*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)
+{
+	int div;
+	div = clk_divider_bestdiv(hw, rate, prate);
+
+	return DIV_ROUND_UP(*prate, div);
+}
+
+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 div, value;
+	unsigned long flags = 0;
+	u32 val;
+
+	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))
+		value = div_mask(divider);
+
+	if (divider->lock)
+		spin_lock_irqsave(divider->lock, flags);
+
+	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;
+	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);
+
+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,
+		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;
+	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);