arch/sh/kernel/cpu/sh4/clock-sh4-202.c

   1 /*
   2  * arch/sh/kernel/cpu/sh4/clock-sh4-202.c
   3  *
   4  * Additional SH4-202 support for the clock framework
   5  *
   6  *  Copyright (C) 2005  Paul Mundt
   7  *
   8  * This file is subject to the terms and conditions of the GNU General Public
   9  * License.  See the file "COPYING" in the main directory of this archive
  10  * for more details.
  11  */
  12 #include <linux/init.h>
  13 #include <linux/kernel.h>
  14 #include <linux/err.h>
  15 #include <linux/io.h>
  16 #include <linux/clkdev.h>
  17 #include <asm/clock.h>
  18 #include <asm/freq.h>
  19
  20 #define CPG2_FRQCR3     0xfe0a0018
  21
  22 static int frqcr3_divisors[] = { 1, 2, 3, 4, 6, 8, 16 };
  23 static int frqcr3_values[]   = { 0, 1, 2, 3, 4, 5, 6  };
  24
  25 static unsigned long emi_clk_recalc(struct clk *clk)
  26 {
  27         int idx = __raw_readl(CPG2_FRQCR3) & 0x0007;
  28         return clk->parent->rate / frqcr3_divisors[idx];
  29 }
  30
  31 static inline int frqcr3_lookup(struct clk *clk, unsigned long rate)
  32 {
  33         int divisor = clk->parent->rate / rate;
  34         int i;
  35
  36         for (i = 0; i < ARRAY_SIZE(frqcr3_divisors); i++)
  37                 if (frqcr3_divisors[i] == divisor)
  38                         return frqcr3_values[i];
  39
  40         /* Safe fallback */
  41         return 5;
  42 }
  43
  44 static struct clk_ops sh4202_emi_clk_ops = {
  45         .recalc         = emi_clk_recalc,
  46 };
  47
  48 static struct clk sh4202_emi_clk = {
  49         .flags          = CLK_ENABLE_ON_INIT,
  50         .ops            = &sh4202_emi_clk_ops,
  51 };
  52
  53 static unsigned long femi_clk_recalc(struct clk *clk)
  54 {
  55         int idx = (__raw_readl(CPG2_FRQCR3) >> 3) & 0x0007;
  56         return clk->parent->rate / frqcr3_divisors[idx];
  57 }
  58
  59 static struct clk_ops sh4202_femi_clk_ops = {
  60         .recalc         = femi_clk_recalc,
  61 };
  62
  63 static struct clk sh4202_femi_clk = {
  64         .flags          = CLK_ENABLE_ON_INIT,
  65         .ops            = &sh4202_femi_clk_ops,
  66 };
  67
  68 static void shoc_clk_init(struct clk *clk)
  69 {
  70         int i;
  71
  72         /*
  73          * For some reason, the shoc_clk seems to be set to some really
  74          * insane value at boot (values outside of the allowable frequency
  75          * range for instance). We deal with this by scaling it back down
  76          * to something sensible just in case.
  77          *
  78          * Start scaling from the high end down until we find something
  79          * that passes rate verification..
  80          */
  81         for (i = 0; i < ARRAY_SIZE(frqcr3_divisors); i++) {
  82                 int divisor = frqcr3_divisors[i];
  83
  84                 if (clk->ops->set_rate(clk, clk->parent->rate / divisor) == 0)
  85                         break;
  86         }
  87
  88         WARN_ON(i == ARRAY_SIZE(frqcr3_divisors));      /* Undefined clock */
  89 }
  90
  91 static unsigned long shoc_clk_recalc(struct clk *clk)
  92 {
  93         int idx = (__raw_readl(CPG2_FRQCR3) >> 6) & 0x0007;
  94         return clk->parent->rate / frqcr3_divisors[idx];
  95 }
  96
  97 static int shoc_clk_verify_rate(struct clk *clk, unsigned long rate)
  98 {
  99         struct clk *bclk = clk_get(NULL, "bus_clk");
 100         unsigned long bclk_rate = clk_get_rate(bclk);
 101
 102         clk_put(bclk);
 103
 104         if (rate > bclk_rate)
 105                 return 1;
 106         if (rate > 66000000)
 107                 return 1;
 108
 109         return 0;
 110 }
 111
 112 static int shoc_clk_set_rate(struct clk *clk, unsigned long rate)
 113 {
 114         unsigned long frqcr3;
 115         unsigned int tmp;
 116
 117         /* Make sure we have something sensible to switch to */
 118         if (shoc_clk_verify_rate(clk, rate) != 0)
 119                 return -EINVAL;
 120
 121         tmp = frqcr3_lookup(clk, rate);
 122
 123         frqcr3 = __raw_readl(CPG2_FRQCR3);
 124         frqcr3 &= ~(0x0007 << 6);
 125         frqcr3 |= tmp << 6;
 126         __raw_writel(frqcr3, CPG2_FRQCR3);
 127
 128         clk->rate = clk->parent->rate / frqcr3_divisors[tmp];
 129
 130         return 0;
 131 }
 132
 133 static struct clk_ops sh4202_shoc_clk_ops = {
 134         .init           = shoc_clk_init,
 135         .recalc         = shoc_clk_recalc,
 136         .set_rate       = shoc_clk_set_rate,
 137 };
 138
 139 static struct clk sh4202_shoc_clk = {
 140         .flags          = CLK_ENABLE_ON_INIT,
 141         .ops            = &sh4202_shoc_clk_ops,
 142 };
 143
 144 static struct clk *sh4202_onchip_clocks[] = {
 145         &sh4202_emi_clk,
 146         &sh4202_femi_clk,
 147         &sh4202_shoc_clk,
 148 };
 149
 150 static struct clk_lookup lookups[] = {
 151         /* main clocks */
 152         CLKDEV_CON_ID("emi_clk", &sh4202_emi_clk),
 153         CLKDEV_CON_ID("femi_clk", &sh4202_femi_clk),
 154         CLKDEV_CON_ID("shoc_clk", &sh4202_shoc_clk),
 155 };
 156
 157 int __init arch_clk_init(void)
 158 {
 159         struct clk *clk;
 160         int i, ret = 0;
 161
 162         cpg_clk_init();
 163
 164         clk = clk_get(NULL, "master_clk");
 165         for (i = 0; i < ARRAY_SIZE(sh4202_onchip_clocks); i++) {
 166                 struct clk *clkp = sh4202_onchip_clocks[i];
 167
 168                 clkp->parent = clk;
 169                 ret |= clk_register(clkp);
 170         }
 171
 172         clk_put(clk);
 173
 174         clkdev_add_table(lookups, ARRAY_SIZE(lookups));
 175
 176         return ret;
 177 }