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/kernel.h>
  17 #include <linux/slab.h>
  18 #include <linux/export.h>
  19 #include <linux/err.h>
  20 #include <linux/clk-provider.h>
  21 #include <linux/io.h>
  22
  23 #include "clk-icst.h"
  24
  25 /**
  26  * struct clk_icst - ICST VCO clock wrapper
  27  * @hw: corresponding clock hardware entry
  28  * @vcoreg: VCO register address
  29  * @lockreg: VCO lock register address
  30  * @params: parameters for this ICST instance
  31  * @rate: current rate
  32  */
  33 struct clk_icst {
  34         struct clk_hw hw;
  35         void __iomem *vcoreg;
  36         void __iomem *lockreg;
  37         struct icst_params *params;
  38         unsigned long rate;
  39 };
  40
  41 #define to_icst(_hw) container_of(_hw, struct clk_icst, hw)
  42
  43 /**
  44  * vco_get() - get ICST VCO settings from a certain register
  45  * @vcoreg: register containing the VCO settings
  46  */
  47 static struct icst_vco vco_get(void __iomem *vcoreg)
  48 {
  49         u32 val;
  50         struct icst_vco vco;
  51
  52         val = readl(vcoreg);
  53         vco.v = val & 0x1ff;
  54         vco.r = (val >> 9) & 0x7f;
  55         vco.s = (val >> 16) & 03;
  56         return vco;
  57 }
  58
  59 /**
  60  * vco_set() - commit changes to an ICST VCO
  61  * @locreg: register to poke to unlock the VCO for writing
  62  * @vcoreg: register containing the VCO settings
  63  * @vco: ICST VCO parameters to commit
  64  */
  65 static void vco_set(void __iomem *lockreg,
  66                         void __iomem *vcoreg,
  67                         struct icst_vco vco)
  68 {
  69         u32 val;
  70
  71         val = readl(vcoreg) & ~0x7ffff;
  72         val |= vco.v | (vco.r << 9) | (vco.s << 16);
  73
  74         /* This magic unlocks the VCO so it can be controlled */
  75         writel(0xa05f, lockreg);
  76         writel(val, vcoreg);
  77         /* This locks the VCO again */
  78         writel(0, lockreg);
  79 }
  80
  81
  82 static unsigned long icst_recalc_rate(struct clk_hw *hw,
  83                                       unsigned long parent_rate)
  84 {
  85         struct clk_icst *icst = to_icst(hw);
  86         struct icst_vco vco;
  87
  88         if (parent_rate)
  89                 icst->params->ref = parent_rate;
  90         vco = vco_get(icst->vcoreg);
  91         icst->rate = icst_hz(icst->params, vco);
  92         return icst->rate;
  93 }
  94
  95 static long icst_round_rate(struct clk_hw *hw, unsigned long rate,
  96                             unsigned long *prate)
  97 {
  98         struct clk_icst *icst = to_icst(hw);
  99         struct icst_vco vco;
 100
 101         vco = icst_hz_to_vco(icst->params, rate);
 102         return icst_hz(icst->params, vco);
 103 }
 104
 105 static int icst_set_rate(struct clk_hw *hw, unsigned long rate,
 106                          unsigned long parent_rate)
 107 {
 108         struct clk_icst *icst = to_icst(hw);
 109         struct icst_vco vco;
 110
 111         if (parent_rate)
 112                 icst->params->ref = parent_rate;
 113         vco = icst_hz_to_vco(icst->params, rate);
 114         icst->rate = icst_hz(icst->params, vco);
 115         vco_set(icst->lockreg, icst->vcoreg, vco);
 116         return 0;
 117 }
 118
 119 static const struct clk_ops icst_ops = {
 120         .recalc_rate = icst_recalc_rate,
 121         .round_rate = icst_round_rate,
 122         .set_rate = icst_set_rate,
 123 };
 124
 125 struct clk *icst_clk_register(struct device *dev,
 126                         const struct clk_icst_desc *desc,
 127                         const char *name,
 128                         const char *parent_name,
 129                         void __iomem *base)
 130 {
 131         struct clk *clk;
 132         struct clk_icst *icst;
 133         struct clk_init_data init;
 134         struct icst_params *pclone;
 135
 136         icst = kzalloc(sizeof(struct clk_icst), GFP_KERNEL);
 137         if (!icst) {
 138                 pr_err("could not allocate ICST clock!\n");
 139                 return ERR_PTR(-ENOMEM);
 140         }
 141
 142         pclone = kmemdup(desc->params, sizeof(*pclone), GFP_KERNEL);
 143         if (!pclone) {
 144                 kfree(icst);
 145                 pr_err("could not clone ICST params\n");
 146                 return ERR_PTR(-ENOMEM);
 147         }
 148
 149         init.name = name;
 150         init.ops = &icst_ops;
 151         init.flags = CLK_IS_ROOT;
 152         init.parent_names = (parent_name ? &parent_name : NULL);
 153         init.num_parents = (parent_name ? 1 : 0);
 154         icst->hw.init = &init;
 155         icst->params = pclone;
 156         icst->vcoreg = base + desc->vco_offset;
 157         icst->lockreg = base + desc->lock_offset;
 158
 159         clk = clk_register(dev, &icst->hw);
 160         if (IS_ERR(clk)) {
 161                 kfree(pclone);
 162                 kfree(icst);
 163         }
 164
 165         return clk;
 166 }
 167 EXPORT_SYMBOL_GPL(icst_clk_register);