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) 2012-2015 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 #include <linux/regmap.h>
  23 #include <linux/mfd/syscon.h>
  24
  25 #include "clk-icst.h"
  26
  27 /* Magic unlocking token used on all Versatile boards */
  28 #define VERSATILE_LOCK_VAL      0xA05F
  29
  30 /**
  31  * struct clk_icst - ICST VCO clock wrapper
  32  * @hw: corresponding clock hardware entry
  33  * @vcoreg: VCO register address
  34  * @lockreg: VCO lock register address
  35  * @params: parameters for this ICST instance
  36  * @rate: current rate
  37  */
  38 struct clk_icst {
  39         struct clk_hw hw;
  40         struct regmap *map;
  41         u32 vcoreg_off;
  42         u32 lockreg_off;
  43         struct icst_params *params;
  44         unsigned long rate;
  45 };
  46
  47 #define to_icst(_hw) container_of(_hw, struct clk_icst, hw)
  48
  49 /**
  50  * vco_get() - get ICST VCO settings from a certain ICST
  51  * @icst: the ICST clock to get
  52  * @vco: the VCO struct to return the value in
  53  */
  54 static int vco_get(struct clk_icst *icst, struct icst_vco *vco)
  55 {
  56         u32 val;
  57         int ret;
  58
  59         ret = regmap_read(icst->map, icst->vcoreg_off, &val);
  60         if (ret)
  61                 return ret;
  62         vco->v = val & 0x1ff;
  63         vco->r = (val >> 9) & 0x7f;
  64         vco->s = (val >> 16) & 03;
  65         return 0;
  66 }
  67
  68 /**
  69  * vco_set() - commit changes to an ICST VCO
  70  * @icst: the ICST clock to set
  71  * @vco: the VCO struct to set the changes from
  72  */
  73 static int vco_set(struct clk_icst *icst, struct icst_vco vco)
  74 {
  75         u32 val;
  76         int ret;
  77
  78         ret = regmap_read(icst->map, icst->vcoreg_off, &val);
  79         if (ret)
  80                 return ret;
  81
  82         /* Mask the 18 bits used by the VCO */
  83         val &= ~0x7ffff;
  84         val |= vco.v | (vco.r << 9) | (vco.s << 16);
  85
  86         /* This magic unlocks the VCO so it can be controlled */
  87         ret = regmap_write(icst->map, icst->lockreg_off, VERSATILE_LOCK_VAL);
  88         if (ret)
  89                 return ret;
  90         ret = regmap_write(icst->map, icst->vcoreg_off, val);
  91         if (ret)
  92                 return ret;
  93         /* This locks the VCO again */
  94         ret = regmap_write(icst->map, icst->lockreg_off, 0);
  95         if (ret)
  96                 return ret;
  97         return 0;
  98 }
  99
 100 static unsigned long icst_recalc_rate(struct clk_hw *hw,
 101                                       unsigned long parent_rate)
 102 {
 103         struct clk_icst *icst = to_icst(hw);
 104         struct icst_vco vco;
 105         int ret;
 106
 107         if (parent_rate)
 108                 icst->params->ref = parent_rate;
 109         ret = vco_get(icst, &vco);
 110         if (ret) {
 111                 pr_err("ICST: could not get VCO setting\n");
 112                 return 0;
 113         }
 114         icst->rate = icst_hz(icst->params, vco);
 115         return icst->rate;
 116 }
 117
 118 static long icst_round_rate(struct clk_hw *hw, unsigned long rate,
 119                             unsigned long *prate)
 120 {
 121         struct clk_icst *icst = to_icst(hw);
 122         struct icst_vco vco;
 123
 124         vco = icst_hz_to_vco(icst->params, rate);
 125         return icst_hz(icst->params, vco);
 126 }
 127
 128 static int icst_set_rate(struct clk_hw *hw, unsigned long rate,
 129                          unsigned long parent_rate)
 130 {
 131         struct clk_icst *icst = to_icst(hw);
 132         struct icst_vco vco;
 133
 134         if (parent_rate)
 135                 icst->params->ref = parent_rate;
 136         vco = icst_hz_to_vco(icst->params, rate);
 137         icst->rate = icst_hz(icst->params, vco);
 138         return vco_set(icst, vco);
 139 }
 140
 141 static const struct clk_ops icst_ops = {
 142         .recalc_rate = icst_recalc_rate,
 143         .round_rate = icst_round_rate,
 144         .set_rate = icst_set_rate,
 145 };
 146
 147 static struct clk *icst_clk_setup(struct device *dev,
 148                                   const struct clk_icst_desc *desc,
 149                                   const char *name,
 150                                   const char *parent_name,
 151                                   struct regmap *map)
 152 {
 153         struct clk *clk;
 154         struct clk_icst *icst;
 155         struct clk_init_data init;
 156         struct icst_params *pclone;
 157
 158         icst = kzalloc(sizeof(struct clk_icst), GFP_KERNEL);
 159         if (!icst) {
 160                 pr_err("could not allocate ICST clock!\n");
 161                 return ERR_PTR(-ENOMEM);
 162         }
 163
 164         pclone = kmemdup(desc->params, sizeof(*pclone), GFP_KERNEL);
 165         if (!pclone) {
 166                 kfree(icst);
 167                 pr_err("could not clone ICST params\n");
 168                 return ERR_PTR(-ENOMEM);
 169         }
 170
 171         init.name = name;
 172         init.ops = &icst_ops;
 173         init.flags = 0;
 174         init.parent_names = (parent_name ? &parent_name : NULL);
 175         init.num_parents = (parent_name ? 1 : 0);
 176         icst->map = map;
 177         icst->hw.init = &init;
 178         icst->params = pclone;
 179         icst->vcoreg_off = desc->vco_offset;
 180         icst->lockreg_off = desc->lock_offset;
 181
 182         clk = clk_register(dev, &icst->hw);
 183         if (IS_ERR(clk)) {
 184                 kfree(pclone);
 185                 kfree(icst);
 186         }
 187
 188         return clk;
 189 }
 190
 191 struct clk *icst_clk_register(struct device *dev,
 192                         const struct clk_icst_desc *desc,
 193                         const char *name,
 194                         const char *parent_name,
 195                         void __iomem *base)
 196 {
 197         struct regmap_config icst_regmap_conf = {
 198                 .reg_bits = 32,
 199                 .val_bits = 32,
 200                 .reg_stride = 4,
 201         };
 202         struct regmap *map;
 203
 204         map = regmap_init_mmio(dev, base, &icst_regmap_conf);
 205         if (IS_ERR(map)) {
 206                 pr_err("could not initialize ICST regmap\n");
 207                 return ERR_CAST(map);
 208         }
 209         return icst_clk_setup(dev, desc, name, parent_name, map);
 210 }
 211 EXPORT_SYMBOL_GPL(icst_clk_register);
 212
 213 #ifdef CONFIG_OF
 214 /*
 215  * In a device tree, an memory-mapped ICST clock appear as a child
 216  * of a syscon node. Assume this and probe it only as a child of a
 217  * syscon.
 218  */
 219
 220 static const struct icst_params icst525_params = {
 221         .vco_max        = ICST525_VCO_MAX_5V,
 222         .vco_min        = ICST525_VCO_MIN,
 223         .vd_min         = 8,
 224         .vd_max         = 263,
 225         .rd_min         = 3,
 226         .rd_max         = 65,
 227         .s2div          = icst525_s2div,
 228         .idx2s          = icst525_idx2s,
 229 };
 230
 231 static const struct icst_params icst307_params = {
 232         .vco_max        = ICST307_VCO_MAX,
 233         .vco_min        = ICST307_VCO_MIN,
 234         .vd_min         = 4 + 8,
 235         .vd_max         = 511 + 8,
 236         .rd_min         = 1 + 2,
 237         .rd_max         = 127 + 2,
 238         .s2div          = icst307_s2div,
 239         .idx2s          = icst307_idx2s,
 240 };
 241
 242 static void __init of_syscon_icst_setup(struct device_node *np)
 243 {
 244         struct device_node *parent;
 245         struct regmap *map;
 246         struct clk_icst_desc icst_desc;
 247         const char *name = np->name;
 248         const char *parent_name;
 249         struct clk *regclk;
 250
 251         /* We do not release this reference, we are using it perpetually */
 252         parent = of_get_parent(np);
 253         if (!parent) {
 254                 pr_err("no parent node for syscon ICST clock\n");
 255                 return;
 256         }
 257         map = syscon_node_to_regmap(parent);
 258         if (IS_ERR(map)) {
 259                 pr_err("no regmap for syscon ICST clock parent\n");
 260                 return;
 261         }
 262
 263         if (of_property_read_u32(np, "vco-offset", &icst_desc.vco_offset)) {
 264                 pr_err("no VCO register offset for ICST clock\n");
 265                 return;
 266         }
 267         if (of_property_read_u32(np, "lock-offset", &icst_desc.lock_offset)) {
 268                 pr_err("no lock register offset for ICST clock\n");
 269                 return;
 270         }
 271
 272         if (of_device_is_compatible(np, "arm,syscon-icst525"))
 273                 icst_desc.params = &icst525_params;
 274         else if (of_device_is_compatible(np, "arm,syscon-icst307"))
 275                 icst_desc.params = &icst307_params;
 276         else {
 277                 pr_err("unknown ICST clock %s\n", name);
 278                 return;
 279         }
 280
 281         /* Parent clock name is not the same as node parent */
 282         parent_name = of_clk_get_parent_name(np, 0);
 283
 284         regclk = icst_clk_setup(NULL, &icst_desc, name, parent_name, map);
 285         if (IS_ERR(regclk)) {
 286                 pr_err("error setting up syscon ICST clock %s\n", name);
 287                 return;
 288         }
 289         of_clk_add_provider(np, of_clk_src_simple_get, regclk);
 290         pr_debug("registered syscon ICST clock %s\n", name);
 291 }
 292
 293 CLK_OF_DECLARE(arm_syscon_icst525_clk,
 294                "arm,syscon-icst525", of_syscon_icst_setup);
 295 CLK_OF_DECLARE(arm_syscon_icst307_clk,
 296                "arm,syscon-icst307", of_syscon_icst_setup);
 297
 298 #endif