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  */
  32 struct 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  */
  46 static 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  */
  64 static 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
  81 static 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
  92 static 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
 102 static 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
 114 static 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
 120 struct clk *icst_clk_register(struct device *dev,
 121                         const struct clk_icst_desc *desc,
 122                         void __iomem *base)
 123 {
 124         struct clk *clk;
 125         struct clk_icst *icst;
 126         struct clk_init_data init;
 127
 128         icst = kzalloc(sizeof(struct clk_icst), GFP_KERNEL);
 129         if (!icst) {
 130                 pr_err("could not allocate ICST clock!\n");
 131                 return ERR_PTR(-ENOMEM);
 132         }
 133         init.name = "icst";
 134         init.ops = &icst_ops;
 135         init.flags = CLK_IS_ROOT;
 136         init.parent_names = NULL;
 137         init.num_parents = 0;
 138         icst->hw.init = &init;
 139         icst->params = desc->params;
 140         icst->vcoreg = base + desc->vco_offset;
 141         icst->lockreg = base + desc->lock_offset;
 142
 143         clk = clk_register(dev, &icst->hw);
 144         if (IS_ERR(clk))
 145                 kfree(icst);
 146
 147         return clk;
 148 }