LXR linux/drivers/clk/versatile/clk-icst.c

   1/*
   2 * Driver for the ICST307 VCO clock found in the ARM Reference designs.
   3 * We wrap the custom interface from <asm/hardware/icst.h> into the generic
   4 * clock framework.
   5 *
   6 * Copyright (C) 2012 Linus Walleij
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 *
  12 * TODO: when all ARM reference designs are migrated to generic clocks, the
  13 * ICST clock code from the ARM tree should probably be merged into this
  14 * file.
  15 */
  16#include <linux/clk.h>
  17#include <linux/clkdev.h>
  18#include <linux/err.h>
  19#include <linux/clk-provider.h>
  20#include <linux/io.h>
  21
  22#include "clk-icst.h"
  23
  24/**
  25 * struct clk_icst - ICST VCO clock wrapper
  26 * @hw: corresponding clock hardware entry
  27 * @vcoreg: VCO register address
  28 * @lockreg: VCO lock register address
  29 * @params: parameters for this ICST instance
  30 * @rate: current rate
  31 */
  32struct clk_icst {
  33        struct clk_hw hw;
  34        void __iomem *vcoreg;
  35        void __iomem *lockreg;
  36        const struct icst_params *params;
  37        unsigned long rate;
  38};
  39
  40#define to_icst(_hw) container_of(_hw, struct clk_icst, hw)
  41
  42/**
  43 * vco_get() - get ICST VCO settings from a certain register
  44 * @vcoreg: register containing the VCO settings
  45 */
  46static struct icst_vco vco_get(void __iomem *vcoreg)
  47{
  48        u32 val;
  49        struct icst_vco vco;
  50
  51        val = readl(vcoreg);
  52        vco.v = val & 0x1ff;
  53        vco.r = (val >> 9) & 0x7f;
  54        vco.s = (val >> 16) & 03;
  55        return vco;
  56}
  57
  58/**
  59 * vco_set() - commit changes to an ICST VCO
  60 * @locreg: register to poke to unlock the VCO for writing
  61 * @vcoreg: register containing the VCO settings
  62 * @vco: ICST VCO parameters to commit
  63 */
  64static void vco_set(void __iomem *lockreg,
  65                        void __iomem *vcoreg,
  66                        struct icst_vco vco)
  67{
  68        u32 val;
  69
  70        val = readl(vcoreg) & ~0x7ffff;
  71        val |= vco.v | (vco.r << 9) | (vco.s << 16);
  72
  73        /* This magic unlocks the VCO so it can be controlled */
  74        writel(0xa05f, lockreg);
  75        writel(val, vcoreg);
  76        /* This locks the VCO again */
  77        writel(0, lockreg);
  78}
  79
  80
  81static unsigned long icst_recalc_rate(struct clk_hw *hw,
  82                                      unsigned long parent_rate)
  83{
  84        struct clk_icst *icst = to_icst(hw);
  85        struct icst_vco vco;
  86
  87        vco = vco_get(icst->vcoreg);
  88        icst->rate = icst_hz(icst->params, vco);
  89        return icst->rate;
  90}
  91
  92static long icst_round_rate(struct clk_hw *hw, unsigned long rate,
  93                            unsigned long *prate)
  94{
  95        struct clk_icst *icst = to_icst(hw);
  96        struct icst_vco vco;
  97
  98        vco = icst_hz_to_vco(icst->params, rate);
  99        return icst_hz(icst->params, vco);
 100}
 101
 102static int icst_set_rate(struct clk_hw *hw, unsigned long rate,
 103                         unsigned long parent_rate)
 104{
 105        struct clk_icst *icst = to_icst(hw);
 106        struct icst_vco vco;
 107
 108        vco = icst_hz_to_vco(icst->params, rate);
 109        icst->rate = icst_hz(icst->params, vco);
 110        vco_set(icst->lockreg, icst->vcoreg, vco);
 111        return 0;
 112}
 113
 114static const struct clk_ops icst_ops = {
 115        .recalc_rate = icst_recalc_rate,
 116        .round_rate = icst_round_rate,
 117        .set_rate = icst_set_rate,
 118};
 119
 120struct clk *icst_clk_register(struct device *dev,
 121                        const struct clk_icst_desc *desc,
 122                        const char *name,
 123                        void __iomem *base)
 124{
 125        struct clk *clk;
 126        struct clk_icst *icst;
 127        struct clk_init_data init;
 128
 129        icst = kzalloc(sizeof(struct clk_icst), GFP_KERNEL);
 130        if (!icst) {
 131                pr_err("could not allocate ICST clock!\n");
 132                return ERR_PTR(-ENOMEM);
 133        }
 134        init.name = name;
 135        init.ops = &icst_ops;
 136        init.flags = CLK_IS_ROOT;
 137        init.parent_names = NULL;
 138        init.num_parents = 0;
 139        icst->hw.init = &init;
 140        icst->params = desc->params;
 141        icst->vcoreg = base + desc->vco_offset;
 142        icst->lockreg = base + desc->lock_offset;
 143
 144        clk = clk_register(dev, &icst->hw);
 145        if (IS_ERR(clk))
 146                kfree(icst);
 147
 148        return clk;
 149}
 150