clk-ref.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Copyright 2012 Freescale Semiconductor, Inc.
  4 */
  5
  6#include <linux/clk-provider.h>
  7#include <linux/err.h>
  8#include <linux/io.h>
  9#include <linux/slab.h>
 10#include "clk.h"
 11
 12/**
 13 * struct clk_ref - mxs reference clock
 14 * @hw: clk_hw for the reference clock
 15 * @reg: register address
 16 * @idx: the index of the reference clock within the same register
 17 *
 18 * The mxs reference clock sources from pll.  Every 4 reference clocks share
 19 * one register space, and @idx is used to identify them.  Each reference
 20 * clock has a gate control and a fractional * divider.  The rate is calculated
 21 * as pll rate  * (18 / FRAC), where FRAC = 18 ~ 35.
 22 */
 23struct clk_ref {
 24	struct clk_hw hw;
 25	void __iomem *reg;
 26	u8 idx;
 27};
 28
 29#define to_clk_ref(_hw) container_of(_hw, struct clk_ref, hw)
 30
 31static int clk_ref_enable(struct clk_hw *hw)
 32{
 33	struct clk_ref *ref = to_clk_ref(hw);
 34
 35	writel_relaxed(1 << ((ref->idx + 1) * 8 - 1), ref->reg + CLR);
 36
 37	return 0;
 38}
 39
 40static void clk_ref_disable(struct clk_hw *hw)
 41{
 42	struct clk_ref *ref = to_clk_ref(hw);
 43
 44	writel_relaxed(1 << ((ref->idx + 1) * 8 - 1), ref->reg + SET);
 45}
 46
 47static unsigned long clk_ref_recalc_rate(struct clk_hw *hw,
 48					 unsigned long parent_rate)
 49{
 50	struct clk_ref *ref = to_clk_ref(hw);
 51	u64 tmp = parent_rate;
 52	u8 frac = (readl_relaxed(ref->reg) >> (ref->idx * 8)) & 0x3f;
 53
 54	tmp *= 18;
 55	do_div(tmp, frac);
 56
 57	return tmp;
 58}
 59
 60static int clk_ref_determine_rate(struct clk_hw *hw,
 61				  struct clk_rate_request *req)
 62{
 63	unsigned long parent_rate = req->best_parent_rate;
 64	u64 tmp = parent_rate;
 65	u8 frac;
 66
 67	tmp = tmp * 18 + req->rate / 2;
 68	do_div(tmp, req->rate);
 69	frac = clamp(tmp, 18, 35);
 70
 71	tmp = parent_rate;
 72	tmp *= 18;
 73	do_div(tmp, frac);
 74
 75	req->rate = tmp;
 76
 77	return 0;
 78}
 79
 80static int clk_ref_set_rate(struct clk_hw *hw, unsigned long rate,
 81			    unsigned long parent_rate)
 82{
 83	struct clk_ref *ref = to_clk_ref(hw);
 84	unsigned long flags;
 85	u64 tmp = parent_rate;
 86	u32 val;
 87	u8 frac, shift = ref->idx * 8;
 88
 89	tmp = tmp * 18 + rate / 2;
 90	do_div(tmp, rate);
 91	frac = clamp(tmp, 18, 35);
 92
 93	spin_lock_irqsave(&mxs_lock, flags);
 94
 95	val = readl_relaxed(ref->reg);
 96	val &= ~(0x3f << shift);
 97	val |= frac << shift;
 98	writel_relaxed(val, ref->reg);
 99
100	spin_unlock_irqrestore(&mxs_lock, flags);
101
102	return 0;
103}
104
105static const struct clk_ops clk_ref_ops = {
106	.enable		= clk_ref_enable,
107	.disable	= clk_ref_disable,
108	.recalc_rate	= clk_ref_recalc_rate,
109	.determine_rate = clk_ref_determine_rate,
110	.set_rate	= clk_ref_set_rate,
111};
112
113struct clk *mxs_clk_ref(const char *name, const char *parent_name,
114			void __iomem *reg, u8 idx)
115{
116	struct clk_ref *ref;
117	struct clk *clk;
118	struct clk_init_data init;
119
120	ref = kzalloc(sizeof(*ref), GFP_KERNEL);
121	if (!ref)
122		return ERR_PTR(-ENOMEM);
123
124	init.name = name;
125	init.ops = &clk_ref_ops;
126	init.flags = 0;
127	init.parent_names = (parent_name ? &parent_name: NULL);
128	init.num_parents = (parent_name ? 1 : 0);
129
130	ref->reg = reg;
131	ref->idx = idx;
132	ref->hw.init = &init;
133
134	clk = clk_register(NULL, &ref->hw);
135	if (IS_ERR(clk))
136		kfree(ref);
137
138	return clk;
139}