diff options
author | Ingo Molnar <mingo@kernel.org> | 2012-04-14 13:18:27 +0200 |
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committer | Ingo Molnar <mingo@kernel.org> | 2012-04-14 13:19:04 +0200 |
commit | 6ac1ef482d7ae0c690f1640bf6eb818ff9a2d91e (patch) | |
tree | 021cc9f6b477146fcebe6f3be4752abfa2ba18a9 /drivers/clk/clk-divider.c | |
parent | 682968e0c425c60f0dde37977e5beb2b12ddc4cc (diff) | |
parent | a385ec4f11bdcf81af094c03e2444ee9b7fad2e5 (diff) |
Merge branch 'perf/core' into perf/uprobes
Merge in latest upstream (and the latest perf development tree),
to prepare for tooling changes, and also to pick up v3.4 MM
changes that the uprobes code needs to take care of.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'drivers/clk/clk-divider.c')
-rw-r--r-- | drivers/clk/clk-divider.c | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c new file mode 100644 index 00000000000..d5ac6a75ea5 --- /dev/null +++ b/drivers/clk/clk-divider.c @@ -0,0 +1,200 @@ +/* + * 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> + +/* + * 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 = 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 long clk_divider_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct clk_divider *divider = to_clk_divider(hw); + unsigned int div; + + div = readl(divider->reg) >> divider->shift; + div &= div_mask(divider); + + if (!(divider->flags & CLK_DIVIDER_ONE_BASED)) + div++; + + return parent_rate / div; +} +EXPORT_SYMBOL_GPL(clk_divider_recalc_rate); + +/* + * 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 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; + + if (!rate) + rate = 1; + + maxdiv = (1 << divider->width); + + if (divider->flags & CLK_DIVIDER_ONE_BASED) + maxdiv--; + + if (!best_parent_rate) { + parent_rate = __clk_get_rate(__clk_get_parent(hw->clk)); + bestdiv = DIV_ROUND_UP(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++) { + parent_rate = __clk_round_rate(__clk_get_parent(hw->clk), + MULT_ROUND_UP(rate, i)); + now = parent_rate / i; + if (now <= rate && now > best) { + bestdiv = i; + best = now; + *best_parent_rate = parent_rate; + } + } + + if (!bestdiv) { + bestdiv = (1 << divider->width); + if (divider->flags & CLK_DIVIDER_ONE_BASED) + bestdiv--; + *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); + + if (prate) + return *prate / div; + else { + unsigned long r; + r = __clk_get_rate(__clk_get_parent(hw->clk)); + return r / div; + } +} +EXPORT_SYMBOL_GPL(clk_divider_round_rate); + +static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate) +{ + struct clk_divider *divider = to_clk_divider(hw); + unsigned int div; + unsigned long flags = 0; + u32 val; + + div = __clk_get_rate(__clk_get_parent(hw->clk)) / rate; + + if (!(divider->flags & CLK_DIVIDER_ONE_BASED)) + div--; + + if (div > div_mask(divider)) + div = div_mask(divider); + + if (divider->lock) + spin_lock_irqsave(divider->lock, flags); + + val = readl(divider->reg); + val &= ~(div_mask(divider) << divider->shift); + val |= div << divider->shift; + writel(val, divider->reg); + + if (divider->lock) + spin_unlock_irqrestore(divider->lock, flags); + + return 0; +} +EXPORT_SYMBOL_GPL(clk_divider_set_rate); + +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); + +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) +{ + struct clk_divider *div; + struct clk *clk; + + div = kzalloc(sizeof(struct clk_divider), GFP_KERNEL); + + if (!div) { + pr_err("%s: could not allocate divider clk\n", __func__); + return NULL; + } + + /* struct clk_divider assignments */ + div->reg = reg; + div->shift = shift; + div->width = width; + div->flags = clk_divider_flags; + div->lock = lock; + + if (parent_name) { + div->parent[0] = kstrdup(parent_name, GFP_KERNEL); + if (!div->parent[0]) + goto out; + } + + clk = clk_register(dev, name, + &clk_divider_ops, &div->hw, + div->parent, + (parent_name ? 1 : 0), + flags); + if (clk) + return clk; + +out: + kfree(div->parent[0]); + kfree(div); + + return NULL; +} |