1. 根目录:
2. drivers
3. clk
4. socfpga
5. clk-periph.c

/*
 *  Copyright 2011-2012 Calxeda, Inc.
 *  Copyright (C) 2012-2013 Altera Corporation <www.altera.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * Based from clk-highbank.c
 *
 */
#include <linux/clk.h>
#include <linux/clkdev.h>
#include <linux/clk-provider.h>
#include <linux/io.h>
#include <linux/of.h>

#include "clk.h"

#define to_socfpga_periph_clk(p) container_of(p, struct socfpga_periph_clk, hw.hw)

static unsigned long clk_periclk_recalc_rate(struct clk_hw *hwclk,
					     unsigned long parent_rate)
{
	struct socfpga_periph_clk *socfpgaclk = to_socfpga_periph_clk(hwclk);
	u32 div, val;

	if (socfpgaclk->fixed_div) {
		div = socfpgaclk->fixed_div;
	} else {
		if (socfpgaclk->div_reg) {
			val = readl(socfpgaclk->div_reg) >> socfpgaclk->shift;
			val &= div_mask(socfpgaclk->width);
			parent_rate /= (val + 1);
		}
		div = ((readl(socfpgaclk->hw.reg) & 0x1ff) + 1);
	}

	return parent_rate / div;
}

static const struct clk_ops periclk_ops = {
	.recalc_rate = clk_periclk_recalc_rate,
};

static __init void __socfpga_periph_init(struct device_node *node,
	const struct clk_ops *ops)
{
	u32 reg;
	struct clk *clk;
	struct socfpga_periph_clk *periph_clk;
	const char *clk_name = node->name;
	const char *parent_name;
	struct clk_init_data init;
	int rc;
	u32 fixed_div;
	u32 div_reg[3];

	of_property_read_u32(node, "reg", &reg);

	periph_clk = kzalloc(sizeof(*periph_clk), GFP_KERNEL);
	if (WARN_ON(!periph_clk))
		return;

	periph_clk->hw.reg = clk_mgr_base_addr + reg;

	rc = of_property_read_u32_array(node, "div-reg", div_reg, 3);
	if (!rc) {
		periph_clk->div_reg = clk_mgr_base_addr + div_reg[0];
		periph_clk->shift = div_reg[1];
		periph_clk->width = div_reg[2];
	} else {
		periph_clk->div_reg = 0;
	}

	rc = of_property_read_u32(node, "fixed-divider", &fixed_div);
	if (rc)
		periph_clk->fixed_div = 0;
	else
		periph_clk->fixed_div = fixed_div;

	of_property_read_string(node, "clock-output-names", &clk_name);

	init.name = clk_name;
	init.ops = ops;
	init.flags = 0;
	parent_name = of_clk_get_parent_name(node, 0);
	init.parent_names = &parent_name;
	init.num_parents = 1;

	periph_clk->hw.hw.init = &init;

	clk = clk_register(NULL, &periph_clk->hw.hw);
	if (WARN_ON(IS_ERR(clk))) {
		kfree(periph_clk);
		return;
	}
	rc = of_clk_add_provider(node, of_clk_src_simple_get, clk);
}

void __init socfpga_periph_init(struct device_node *node)
{
	__socfpga_periph_init(node, &periclk_ops);
}