clk-icst.c
3.56 KB
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/*
* Driver for the ICST307 VCO clock found in the ARM Reference designs.
* We wrap the custom interface from <asm/hardware/icst.h> into the generic
* clock framework.
*
* Copyright (C) 2012 Linus Walleij
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* TODO: when all ARM reference designs are migrated to generic clocks, the
* ICST clock code from the ARM tree should probably be merged into this
* file.
*/
#include <linux/clk.h>
#include <linux/clkdev.h>
#include <linux/err.h>
#include <linux/clk-provider.h>
#include <linux/io.h>
#include "clk-icst.h"
/**
* struct clk_icst - ICST VCO clock wrapper
* @hw: corresponding clock hardware entry
* @vcoreg: VCO register address
* @lockreg: VCO lock register address
* @params: parameters for this ICST instance
* @rate: current rate
*/
struct clk_icst {
struct clk_hw hw;
void __iomem *vcoreg;
void __iomem *lockreg;
const struct icst_params *params;
unsigned long rate;
};
#define to_icst(_hw) container_of(_hw, struct clk_icst, hw)
/**
* vco_get() - get ICST VCO settings from a certain register
* @vcoreg: register containing the VCO settings
*/
static struct icst_vco vco_get(void __iomem *vcoreg)
{
u32 val;
struct icst_vco vco;
val = readl(vcoreg);
vco.v = val & 0x1ff;
vco.r = (val >> 9) & 0x7f;
vco.s = (val >> 16) & 03;
return vco;
}
/**
* vco_set() - commit changes to an ICST VCO
* @locreg: register to poke to unlock the VCO for writing
* @vcoreg: register containing the VCO settings
* @vco: ICST VCO parameters to commit
*/
static void vco_set(void __iomem *lockreg,
void __iomem *vcoreg,
struct icst_vco vco)
{
u32 val;
val = readl(vcoreg) & ~0x7ffff;
val |= vco.v | (vco.r << 9) | (vco.s << 16);
/* This magic unlocks the VCO so it can be controlled */
writel(0xa05f, lockreg);
writel(val, vcoreg);
/* This locks the VCO again */
writel(0, lockreg);
}
static unsigned long icst_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct clk_icst *icst = to_icst(hw);
struct icst_vco vco;
vco = vco_get(icst->vcoreg);
icst->rate = icst_hz(icst->params, vco);
return icst->rate;
}
static long icst_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *prate)
{
struct clk_icst *icst = to_icst(hw);
struct icst_vco vco;
vco = icst_hz_to_vco(icst->params, rate);
return icst_hz(icst->params, vco);
}
static int icst_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct clk_icst *icst = to_icst(hw);
struct icst_vco vco;
vco = icst_hz_to_vco(icst->params, rate);
icst->rate = icst_hz(icst->params, vco);
vco_set(icst->lockreg, icst->vcoreg, vco);
return 0;
}
static const struct clk_ops icst_ops = {
.recalc_rate = icst_recalc_rate,
.round_rate = icst_round_rate,
.set_rate = icst_set_rate,
};
struct clk *icst_clk_register(struct device *dev,
const struct clk_icst_desc *desc,
const char *name,
void __iomem *base)
{
struct clk *clk;
struct clk_icst *icst;
struct clk_init_data init;
icst = kzalloc(sizeof(struct clk_icst), GFP_KERNEL);
if (!icst) {
pr_err("could not allocate ICST clock!\n");
return ERR_PTR(-ENOMEM);
}
init.name = name;
init.ops = &icst_ops;
init.flags = CLK_IS_ROOT;
init.parent_names = NULL;
init.num_parents = 0;
icst->hw.init = &init;
icst->params = desc->params;
icst->vcoreg = base + desc->vco_offset;
icst->lockreg = base + desc->lock_offset;
clk = clk_register(dev, &icst->hw);
if (IS_ERR(clk))
kfree(icst);
return clk;
}