arch/arm/plat-samsung/clock-clksrc.c

   1 /* linux/arch/arm/plat-samsung/clock-clksrc.c
   2  *
   3  * Copyright 2008 Simtec Electronics
   4  *      Ben Dooks <ben@simtec.co.uk>
   5  *      http://armlinux.simtec.co.uk/
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10 */
  11
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/kernel.h>
  15 #include <linux/list.h>
  16 #include <linux/errno.h>
  17 #include <linux/err.h>
  18 #include <linux/clk.h>
  19 #include <linux/device.h>
  20 #include <linux/io.h>
  21
  22 #include <plat/clock.h>
  23 #include <plat/clock-clksrc.h>
  24 #include <plat/cpu-freq.h>
  25
  26 static inline struct clksrc_clk *to_clksrc(struct clk *clk)
  27 {
  28         return container_of(clk, struct clksrc_clk, clk);
  29 }
  30
  31 static inline u32 bit_mask(u32 shift, u32 nr_bits)
  32 {
  33         u32 mask = 0xffffffff >> (32 - nr_bits);
  34
  35         return mask << shift;
  36 }
  37
  38 static unsigned long s3c_getrate_clksrc(struct clk *clk)
  39 {
  40         struct clksrc_clk *sclk = to_clksrc(clk);
  41         unsigned long rate = clk_get_rate(clk->parent);
  42         u32 clkdiv = __raw_readl(sclk->reg_div.reg);
  43         u32 mask = bit_mask(sclk->reg_div.shift, sclk->reg_div.size);
  44
  45         clkdiv &= mask;
  46         clkdiv >>= sclk->reg_div.shift;
  47         clkdiv++;
  48
  49         rate /= clkdiv;
  50         return rate;
  51 }
  52
  53 static int s3c_setrate_clksrc(struct clk *clk, unsigned long rate)
  54 {
  55         struct clksrc_clk *sclk = to_clksrc(clk);
  56         void __iomem *reg = sclk->reg_div.reg;
  57         unsigned int div;
  58         u32 mask = bit_mask(sclk->reg_div.shift, sclk->reg_div.size);
  59         u32 val;
  60
  61         rate = clk_round_rate(clk, rate);
  62         div = clk_get_rate(clk->parent) / rate;
  63         if (div > (1 << sclk->reg_div.size))
  64                 return -EINVAL;
  65
  66         val = __raw_readl(reg);
  67         val &= ~mask;
  68         val |= (div - 1) << sclk->reg_div.shift;
  69         __raw_writel(val, reg);
  70
  71         return 0;
  72 }
  73
  74 static int s3c_setparent_clksrc(struct clk *clk, struct clk *parent)
  75 {
  76         struct clksrc_clk *sclk = to_clksrc(clk);
  77         struct clksrc_sources *srcs = sclk->sources;
  78         u32 clksrc = __raw_readl(sclk->reg_src.reg);
  79         u32 mask = bit_mask(sclk->reg_src.shift, sclk->reg_src.size);
  80         int src_nr = -1;
  81         int ptr;
  82
  83         for (ptr = 0; ptr < srcs->nr_sources; ptr++)
  84                 if (srcs->sources[ptr] == parent) {
  85                         src_nr = ptr;
  86                         break;
  87                 }
  88
  89         if (src_nr >= 0) {
  90                 clk->parent = parent;
  91
  92                 clksrc &= ~mask;
  93                 clksrc |= src_nr << sclk->reg_src.shift;
  94
  95                 __raw_writel(clksrc, sclk->reg_src.reg);
  96                 return 0;
  97         }
  98
  99         return -EINVAL;
 100 }
 101
 102 static unsigned long s3c_roundrate_clksrc(struct clk *clk,
 103                                               unsigned long rate)
 104 {
 105         struct clksrc_clk *sclk = to_clksrc(clk);
 106         unsigned long parent_rate = clk_get_rate(clk->parent);
 107         int max_div = 1 << sclk->reg_div.size;
 108         int div;
 109
 110         if (rate >= parent_rate)
 111                 rate = parent_rate;
 112         else {
 113                 div = parent_rate / rate;
 114                 if (parent_rate % rate)
 115                         div++;
 116
 117                 if (div == 0)
 118                         div = 1;
 119                 if (div > max_div)
 120                         div = max_div;
 121
 122                 rate = parent_rate / div;
 123         }
 124
 125         return rate;
 126 }
 127
 128 /* Clock initialisation code */
 129
 130 void __init_or_cpufreq s3c_set_clksrc(struct clksrc_clk *clk, bool announce)
 131 {
 132         struct clksrc_sources *srcs = clk->sources;
 133         u32 mask = bit_mask(clk->reg_src.shift, clk->reg_src.size);
 134         u32 clksrc;
 135
 136         if (!clk->reg_src.reg) {
 137                 if (!clk->clk.parent)
 138                         printk(KERN_ERR "%s: no parent clock specified\n",
 139                                 clk->clk.name);
 140                 return;
 141         }
 142
 143         clksrc = __raw_readl(clk->reg_src.reg);
 144         clksrc &= mask;
 145         clksrc >>= clk->reg_src.shift;
 146
 147         if (clksrc > srcs->nr_sources || !srcs->sources[clksrc]) {
 148                 printk(KERN_ERR "%s: bad source %d\n",
 149                        clk->clk.name, clksrc);
 150                 return;
 151         }
 152
 153         clk->clk.parent = srcs->sources[clksrc];
 154
 155         if (announce)
 156                 printk(KERN_INFO "%s: source is %s (%d), rate is %ld\n",
 157                        clk->clk.name, clk->clk.parent->name, clksrc,
 158                        clk_get_rate(&clk->clk));
 159 }
 160
 161 static struct clk_ops clksrc_ops = {
 162         .set_parent     = s3c_setparent_clksrc,
 163         .get_rate       = s3c_getrate_clksrc,
 164         .set_rate       = s3c_setrate_clksrc,
 165         .round_rate     = s3c_roundrate_clksrc,
 166 };
 167
 168 static struct clk_ops clksrc_ops_nodiv = {
 169         .set_parent     = s3c_setparent_clksrc,
 170 };
 171
 172 static struct clk_ops clksrc_ops_nosrc = {
 173         .get_rate       = s3c_getrate_clksrc,
 174         .set_rate       = s3c_setrate_clksrc,
 175         .round_rate     = s3c_roundrate_clksrc,
 176 };
 177
 178 void __init s3c_register_clksrc(struct clksrc_clk *clksrc, int size)
 179 {
 180         int ret;
 181
 182         for (; size > 0; size--, clksrc++) {
 183                 if (!clksrc->reg_div.reg && !clksrc->reg_src.reg)
 184                         printk(KERN_ERR "%s: clock %s has no registers set\n",
 185                                __func__, clksrc->clk.name);
 186
 187                 /* fill in the default functions */
 188
 189                 if (!clksrc->clk.ops) {
 190                         if (!clksrc->reg_div.reg)
 191                                 clksrc->clk.ops = &clksrc_ops_nodiv;
 192                         else if (!clksrc->reg_src.reg)
 193                                 clksrc->clk.ops = &clksrc_ops_nosrc;
 194                         else
 195                                 clksrc->clk.ops = &clksrc_ops;
 196                 }
 197
 198                 /* setup the clocksource, but do not announce it
 199                  * as it may be re-set by the setup routines
 200                  * called after the rest of the clocks have been
 201                  * registered
 202                  */
 203                 s3c_set_clksrc(clksrc, false);
 204
 205                 ret = s3c24xx_register_clock(&clksrc->clk);
 206
 207                 if (ret < 0) {
 208                         printk(KERN_ERR "%s: failed to register %s (%d)\n",
 209                                __func__, clksrc->clk.name, ret);
 210                 }
 211         }
 212 }