diff options
Diffstat (limited to 'drivers/clk/clk-mux.c')
| -rw-r--r-- | drivers/clk/clk-mux.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c new file mode 100644 index 00000000000..c71ad1f41a9 --- /dev/null +++ b/drivers/clk/clk-mux.c @@ -0,0 +1,116 @@ +/* + * 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. + * + * Simple multiplexer clock implementation + */ + +#include <linux/clk.h> +#include <linux/clk-provider.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/io.h> +#include <linux/err.h> + +/* + * DOC: basic adjustable multiplexer 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 only affected by parent switching. No clk_set_rate support + * parent - parent is adjustable through clk_set_parent + */ + +#define to_clk_mux(_hw) container_of(_hw, struct clk_mux, hw) + +static u8 clk_mux_get_parent(struct clk_hw *hw) +{ + struct clk_mux *mux = to_clk_mux(hw); + u32 val; + + /* + * FIXME need a mux-specific flag to determine if val is bitwise or numeric + * e.g. sys_clkin_ck's clksel field is 3 bits wide, but ranges from 0x1 + * to 0x7 (index starts at one) + * OTOH, pmd_trace_clk_mux_ck uses a separate bit for each clock, so + * val = 0x4 really means "bit 2, index starts at bit 0" + */ + val = readl(mux->reg) >> mux->shift; + val &= (1 << mux->width) - 1; + + if (val && (mux->flags & CLK_MUX_INDEX_BIT)) + val = ffs(val) - 1; + + if (val && (mux->flags & CLK_MUX_INDEX_ONE)) + val--; + + if (val >= __clk_get_num_parents(hw->clk)) + return -EINVAL; + + return val; +} +EXPORT_SYMBOL_GPL(clk_mux_get_parent); + +static int clk_mux_set_parent(struct clk_hw *hw, u8 index) +{ + struct clk_mux *mux = to_clk_mux(hw); + u32 val; + unsigned long flags = 0; + + if (mux->flags & CLK_MUX_INDEX_BIT) + index = (1 << ffs(index)); + + if (mux->flags & CLK_MUX_INDEX_ONE) + index++; + + if (mux->lock) + spin_lock_irqsave(mux->lock, flags); + + val = readl(mux->reg); + val &= ~(((1 << mux->width) - 1) << mux->shift); + val |= index << mux->shift; + writel(val, mux->reg); + + if (mux->lock) + spin_unlock_irqrestore(mux->lock, flags); + + return 0; +} +EXPORT_SYMBOL_GPL(clk_mux_set_parent); + +struct clk_ops clk_mux_ops = { + .get_parent = clk_mux_get_parent, + .set_parent = clk_mux_set_parent, +}; +EXPORT_SYMBOL_GPL(clk_mux_ops); + +struct clk *clk_register_mux(struct device *dev, const char *name, + char **parent_names, u8 num_parents, unsigned long flags, + void __iomem *reg, u8 shift, u8 width, + u8 clk_mux_flags, spinlock_t *lock) +{ + struct clk_mux *mux; + + mux = kmalloc(sizeof(struct clk_mux), GFP_KERNEL); + + if (!mux) { + pr_err("%s: could not allocate mux clk\n", __func__); + return ERR_PTR(-ENOMEM); + } + + /* struct clk_mux assignments */ + mux->reg = reg; + mux->shift = shift; + mux->width = width; + mux->flags = clk_mux_flags; + mux->lock = lock; + + return clk_register(dev, name, &clk_mux_ops, &mux->hw, + parent_names, num_parents, flags); +} |