145 lines
3.1 KiB
C
145 lines
3.1 KiB
C
/*
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* Copyright 2012 Freescale Semiconductor, Inc.
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*
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* The code contained herein is licensed under the GNU General Public
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* License. You may obtain a copy of the GNU General Public License
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* Version 2 or later at the following locations:
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*
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* http://www.opensource.org/licenses/gpl-license.html
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* http://www.gnu.org/copyleft/gpl.html
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*/
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#include <linux/clk-provider.h>
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#include <linux/err.h>
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#include <linux/io.h>
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#include <linux/slab.h>
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#include "clk.h"
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/**
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* struct clk_frac - mxs fractional divider clock
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* @hw: clk_hw for the fractional divider clock
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* @reg: register address
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* @shift: the divider bit shift
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* @width: the divider bit width
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* @busy: busy bit shift
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*
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* The clock is an adjustable fractional divider with a busy bit to wait
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* when the divider is adjusted.
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*/
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struct clk_frac {
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struct clk_hw hw;
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void __iomem *reg;
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u8 shift;
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u8 width;
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u8 busy;
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};
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#define to_clk_frac(_hw) container_of(_hw, struct clk_frac, hw)
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static unsigned long clk_frac_recalc_rate(struct clk_hw *hw,
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unsigned long parent_rate)
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{
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struct clk_frac *frac = to_clk_frac(hw);
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u32 div;
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u64 tmp_rate;
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div = readl_relaxed(frac->reg) >> frac->shift;
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div &= (1 << frac->width) - 1;
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tmp_rate = (u64)parent_rate * div;
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return tmp_rate >> frac->width;
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}
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static long clk_frac_round_rate(struct clk_hw *hw, unsigned long rate,
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unsigned long *prate)
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{
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struct clk_frac *frac = to_clk_frac(hw);
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unsigned long parent_rate = *prate;
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u32 div;
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u64 tmp, tmp_rate, result;
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if (rate > parent_rate)
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return -EINVAL;
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tmp = rate;
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tmp <<= frac->width;
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do_div(tmp, parent_rate);
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div = tmp;
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if (!div)
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return -EINVAL;
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tmp_rate = (u64)parent_rate * div;
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result = tmp_rate >> frac->width;
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if ((result << frac->width) < tmp_rate)
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result += 1;
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return result;
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}
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static int clk_frac_set_rate(struct clk_hw *hw, unsigned long rate,
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unsigned long parent_rate)
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{
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struct clk_frac *frac = to_clk_frac(hw);
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unsigned long flags;
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u32 div, val;
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u64 tmp;
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if (rate > parent_rate)
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return -EINVAL;
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tmp = rate;
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tmp <<= frac->width;
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do_div(tmp, parent_rate);
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div = tmp;
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if (!div)
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return -EINVAL;
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spin_lock_irqsave(&mxs_lock, flags);
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val = readl_relaxed(frac->reg);
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val &= ~(((1 << frac->width) - 1) << frac->shift);
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val |= div << frac->shift;
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writel_relaxed(val, frac->reg);
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spin_unlock_irqrestore(&mxs_lock, flags);
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return mxs_clk_wait(frac->reg, frac->busy);
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}
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static const struct clk_ops clk_frac_ops = {
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.recalc_rate = clk_frac_recalc_rate,
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.round_rate = clk_frac_round_rate,
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.set_rate = clk_frac_set_rate,
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};
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struct clk *mxs_clk_frac(const char *name, const char *parent_name,
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void __iomem *reg, u8 shift, u8 width, u8 busy)
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{
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struct clk_frac *frac;
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struct clk *clk;
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struct clk_init_data init;
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frac = kzalloc(sizeof(*frac), GFP_KERNEL);
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if (!frac)
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return ERR_PTR(-ENOMEM);
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init.name = name;
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init.ops = &clk_frac_ops;
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init.flags = CLK_SET_RATE_PARENT;
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init.parent_names = (parent_name ? &parent_name: NULL);
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init.num_parents = (parent_name ? 1 : 0);
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frac->reg = reg;
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frac->shift = shift;
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frac->width = width;
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frac->busy = busy;
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frac->hw.init = &init;
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clk = clk_register(NULL, &frac->hw);
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if (IS_ERR(clk))
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kfree(frac);
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return clk;
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}
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