linux_kernel/drivers/clk/clk-nspire.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 *  Copyright (C) 2013 Daniel Tang <tangrs@tangrs.id.au>
 */

#include <linux/clk-provider.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>

#define MHZ (1000 * 1000)

#define BASE_CPU_SHIFT		1
#define BASE_CPU_MASK		0x7F

#define CPU_AHB_SHIFT		12
#define CPU_AHB_MASK		0x07

#define FIXED_BASE_SHIFT	8
#define FIXED_BASE_MASK		0x01

#define CLASSIC_BASE_SHIFT	16
#define CLASSIC_BASE_MASK	0x1F

#define CX_BASE_SHIFT		15
#define CX_BASE_MASK		0x3F

#define CX_UNKNOWN_SHIFT	21
#define CX_UNKNOWN_MASK		0x03

struct nspire_clk_info {
	u32 base_clock;
	u16 base_cpu_ratio;
	u16 base_ahb_ratio;
};


#define EXTRACT(var, prop) (((var)>>prop##_SHIFT) & prop##_MASK)
static void nspire_clkinfo_cx(u32 val, struct nspire_clk_info *clk)
{
	if (EXTRACT(val, FIXED_BASE))
		clk->base_clock = 48 * MHZ;
	else
		clk->base_clock = 6 * EXTRACT(val, CX_BASE) * MHZ;

	clk->base_cpu_ratio = EXTRACT(val, BASE_CPU) * EXTRACT(val, CX_UNKNOWN);
	clk->base_ahb_ratio = clk->base_cpu_ratio * (EXTRACT(val, CPU_AHB) + 1);
}

static void nspire_clkinfo_classic(u32 val, struct nspire_clk_info *clk)
{
	if (EXTRACT(val, FIXED_BASE))
		clk->base_clock = 27 * MHZ;
	else
		clk->base_clock = (300 - 6 * EXTRACT(val, CLASSIC_BASE)) * MHZ;

	clk->base_cpu_ratio = EXTRACT(val, BASE_CPU) * 2;
	clk->base_ahb_ratio = clk->base_cpu_ratio * (EXTRACT(val, CPU_AHB) + 1);
}

static void __init nspire_ahbdiv_setup(struct device_node *node,
		void (*get_clkinfo)(u32, struct nspire_clk_info *))
{
	u32 val;
	void __iomem *io;
	struct clk_hw *hw;
	const char *clk_name = node->name;
	const char *parent_name;
	struct nspire_clk_info info;

	io = of_iomap(node, 0);
	if (!io)
		return;
	val = readl(io);
	iounmap(io);

	get_clkinfo(val, &info);

	of_property_read_string(node, "clock-output-names", &clk_name);
	parent_name = of_clk_get_parent_name(node, 0);

	hw = clk_hw_register_fixed_factor(NULL, clk_name, parent_name, 0,
					  1, info.base_ahb_ratio);
	if (!IS_ERR(hw))
		of_clk_add_hw_provider(node, of_clk_hw_simple_get, hw);
}

static void __init nspire_ahbdiv_setup_cx(struct device_node *node)
{
	nspire_ahbdiv_setup(node, nspire_clkinfo_cx);
}

static void __init nspire_ahbdiv_setup_classic(struct device_node *node)
{
	nspire_ahbdiv_setup(node, nspire_clkinfo_classic);
}

CLK_OF_DECLARE(nspire_ahbdiv_cx, "lsi,nspire-cx-ahb-divider",
		nspire_ahbdiv_setup_cx);
CLK_OF_DECLARE(nspire_ahbdiv_classic, "lsi,nspire-classic-ahb-divider",
		nspire_ahbdiv_setup_classic);

static void __init nspire_clk_setup(struct device_node *node,
		void (*get_clkinfo)(u32, struct nspire_clk_info *))
{
	u32 val;
	void __iomem *io;
	struct clk_hw *hw;
	const char *clk_name = node->name;
	struct nspire_clk_info info;

	io = of_iomap(node, 0);
	if (!io)
		return;
	val = readl(io);
	iounmap(io);

	get_clkinfo(val, &info);

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

	hw = clk_hw_register_fixed_rate(NULL, clk_name, NULL, 0,
					info.base_clock);
	if (!IS_ERR(hw))
		of_clk_add_hw_provider(node, of_clk_hw_simple_get, hw);
	else
		return;

	pr_info("TI-NSPIRE Base: %uMHz CPU: %uMHz AHB: %uMHz\n",
		info.base_clock / MHZ,
		info.base_clock / info.base_cpu_ratio / MHZ,
		info.base_clock / info.base_ahb_ratio / MHZ);
}

static void __init nspire_clk_setup_cx(struct device_node *node)
{
	nspire_clk_setup(node, nspire_clkinfo_cx);
}

static void __init nspire_clk_setup_classic(struct device_node *node)
{
	nspire_clk_setup(node, nspire_clkinfo_classic);
}

CLK_OF_DECLARE(nspire_clk_cx, "lsi,nspire-cx-clock", nspire_clk_setup_cx);
CLK_OF_DECLARE(nspire_clk_classic, "lsi,nspire-classic-clock",
		nspire_clk_setup_classic);