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