2 * Copyright (C) 2014 Intel Corporation
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
8 * Adjustable fractional divider clock implementation.
9 * Output rate = (m / n) * parent_rate.
12 #include <linux/clk-provider.h>
13 #include <linux/module.h>
14 #include <linux/device.h>
15 #include <linux/slab.h>
16 #include <linux/gcd.h>
18 #define to_clk_fd(_hw) container_of(_hw, struct clk_fractional_divider, hw)
20 static unsigned long clk_fd_recalc_rate(struct clk_hw *hw,
21 unsigned long parent_rate)
23 struct clk_fractional_divider *fd = to_clk_fd(hw);
24 unsigned long flags = 0;
29 spin_lock_irqsave(fd->lock, flags);
31 val = clk_readl(fd->reg);
34 spin_unlock_irqrestore(fd->lock, flags);
36 m = (val & fd->mmask) >> fd->mshift;
37 n = (val & fd->nmask) >> fd->nshift;
42 ret = (u64)parent_rate * m;
48 static long clk_fd_round_rate(struct clk_hw *hw, unsigned long rate,
51 struct clk_fractional_divider *fd = to_clk_fd(hw);
52 unsigned maxn = (fd->nmask >> fd->nshift) + 1;
55 if (!rate || rate >= *prate)
58 div = gcd(*prate, rate);
60 while ((*prate / div) > maxn) {
68 static int clk_fd_set_rate(struct clk_hw *hw, unsigned long rate,
69 unsigned long parent_rate)
71 struct clk_fractional_divider *fd = to_clk_fd(hw);
72 unsigned long flags = 0;
77 div = gcd(parent_rate, rate);
79 n = parent_rate / div;
82 spin_lock_irqsave(fd->lock, flags);
84 val = clk_readl(fd->reg);
85 val &= ~(fd->mmask | fd->nmask);
86 val |= (m << fd->mshift) | (n << fd->nshift);
87 clk_writel(val, fd->reg);
90 spin_unlock_irqrestore(fd->lock, flags);
95 const struct clk_ops clk_fractional_divider_ops = {
96 .recalc_rate = clk_fd_recalc_rate,
97 .round_rate = clk_fd_round_rate,
98 .set_rate = clk_fd_set_rate,
100 EXPORT_SYMBOL_GPL(clk_fractional_divider_ops);
102 struct clk *clk_register_fractional_divider(struct device *dev,
103 const char *name, const char *parent_name, unsigned long flags,
104 void __iomem *reg, u8 mshift, u8 mwidth, u8 nshift, u8 nwidth,
105 u8 clk_divider_flags, spinlock_t *lock)
107 struct clk_fractional_divider *fd;
108 struct clk_init_data init;
111 fd = kzalloc(sizeof(*fd), GFP_KERNEL);
113 dev_err(dev, "could not allocate fractional divider clk\n");
114 return ERR_PTR(-ENOMEM);
118 init.ops = &clk_fractional_divider_ops;
119 init.flags = flags | CLK_IS_BASIC;
120 init.parent_names = parent_name ? &parent_name : NULL;
121 init.num_parents = parent_name ? 1 : 0;
125 fd->mmask = (BIT(mwidth) - 1) << mshift;
127 fd->nmask = (BIT(nwidth) - 1) << nshift;
128 fd->flags = clk_divider_flags;
132 clk = clk_register(dev, &fd->hw);
138 EXPORT_SYMBOL_GPL(clk_register_fractional_divider);