137 lines
2.8 KiB
C
137 lines
2.8 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 <common.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <io.h>
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#include <asm-generic/div64.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 clk;
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const char *parent;
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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, clk)
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static unsigned long clk_frac_recalc_rate(struct clk *clk,
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unsigned long parent_rate)
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{
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struct clk_frac *frac = to_clk_frac(clk);
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u32 div;
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div = readl(frac->reg) >> frac->shift;
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div &= (1 << frac->width) - 1;
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return (parent_rate >> frac->width) * div;
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}
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static long clk_frac_round_rate(struct clk *clk, 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(clk);
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unsigned long parent_rate = *prate;
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u32 div;
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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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return (parent_rate >> frac->width) * div;
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}
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static int clk_frac_set_rate(struct clk *clk, 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(clk);
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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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val = readl(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(val, frac->reg);
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if (clk_is_enabled(clk))
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while (readl(frac->reg) & 1 << frac->busy);
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return 0;
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}
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static 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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int ret;
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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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frac->parent = parent_name;
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frac->clk.name = name;
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frac->clk.ops = &clk_frac_ops;
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frac->clk.parent_names = &frac->parent;
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frac->clk.num_parents = 1;
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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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ret = clk_register(&frac->clk);
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if (ret)
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return ERR_PTR(ret);
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return &frac->clk;
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}
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