117 lines
3 KiB
C
117 lines
3 KiB
C
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/*
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* Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
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* Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
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* Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Simple multiplexer clock implementation
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*/
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#include <linux/clk.h>
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#include <linux/clk-provider.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/io.h>
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#include <linux/err.h>
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/*
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* DOC: basic adjustable multiplexer clock that cannot gate
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*
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* Traits of this clock:
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* prepare - clk_prepare only ensures that parents are prepared
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* enable - clk_enable only ensures that parents are enabled
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* rate - rate is only affected by parent switching. No clk_set_rate support
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* parent - parent is adjustable through clk_set_parent
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*/
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#define to_clk_mux(_hw) container_of(_hw, struct clk_mux, hw)
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static u8 clk_mux_get_parent(struct clk_hw *hw)
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{
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struct clk_mux *mux = to_clk_mux(hw);
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u32 val;
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/*
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* FIXME need a mux-specific flag to determine if val is bitwise or numeric
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* e.g. sys_clkin_ck's clksel field is 3 bits wide, but ranges from 0x1
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* to 0x7 (index starts at one)
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* OTOH, pmd_trace_clk_mux_ck uses a separate bit for each clock, so
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* val = 0x4 really means "bit 2, index starts at bit 0"
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*/
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val = readl(mux->reg) >> mux->shift;
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val &= (1 << mux->width) - 1;
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if (val && (mux->flags & CLK_MUX_INDEX_BIT))
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val = ffs(val) - 1;
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if (val && (mux->flags & CLK_MUX_INDEX_ONE))
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val--;
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if (val >= __clk_get_num_parents(hw->clk))
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return -EINVAL;
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return val;
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}
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EXPORT_SYMBOL_GPL(clk_mux_get_parent);
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static int clk_mux_set_parent(struct clk_hw *hw, u8 index)
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{
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struct clk_mux *mux = to_clk_mux(hw);
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u32 val;
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unsigned long flags = 0;
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if (mux->flags & CLK_MUX_INDEX_BIT)
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index = (1 << ffs(index));
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if (mux->flags & CLK_MUX_INDEX_ONE)
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index++;
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if (mux->lock)
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spin_lock_irqsave(mux->lock, flags);
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val = readl(mux->reg);
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val &= ~(((1 << mux->width) - 1) << mux->shift);
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val |= index << mux->shift;
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writel(val, mux->reg);
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if (mux->lock)
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spin_unlock_irqrestore(mux->lock, flags);
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return 0;
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}
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EXPORT_SYMBOL_GPL(clk_mux_set_parent);
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struct clk_ops clk_mux_ops = {
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.get_parent = clk_mux_get_parent,
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.set_parent = clk_mux_set_parent,
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};
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EXPORT_SYMBOL_GPL(clk_mux_ops);
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struct clk *clk_register_mux(struct device *dev, const char *name,
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char **parent_names, u8 num_parents, unsigned long flags,
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void __iomem *reg, u8 shift, u8 width,
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u8 clk_mux_flags, spinlock_t *lock)
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{
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struct clk_mux *mux;
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mux = kmalloc(sizeof(struct clk_mux), GFP_KERNEL);
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if (!mux) {
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pr_err("%s: could not allocate mux clk\n", __func__);
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return ERR_PTR(-ENOMEM);
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}
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/* struct clk_mux assignments */
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mux->reg = reg;
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mux->shift = shift;
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mux->width = width;
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mux->flags = clk_mux_flags;
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mux->lock = lock;
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return clk_register(dev, name, &clk_mux_ops, &mux->hw,
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parent_names, num_parents, flags);
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}
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