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 <asm/clock.h>
  16 #include <asm/freq.h>
  17 #include <asm/io.h>
  18
  19 #define CPG2_FRQCR3     0xfe0a0018
  20
  21 static int frqcr3_divisors[] = { 1, 2, 3, 4, 6, 8, 16 };
  22 static int frqcr3_values[]   = { 0, 1, 2, 3, 4, 5, 6  };
  23
  24 static void emi_clk_recalc(struct clk *clk)
  25 {
  26         int idx = ctrl_inl(CPG2_FRQCR3) & 0x0007;
  27         clk->rate = clk->parent->rate / frqcr3_divisors[idx];
  28 }
  29
  30 static inline int frqcr3_lookup(struct clk *clk, unsigned long rate)
  31 {
  32         int divisor = clk->parent->rate / rate;
  33         int i;
  34
  35         for (i = 0; i < ARRAY_SIZE(frqcr3_divisors); i++)
  36                 if (frqcr3_divisors[i] == divisor)
  37                         return frqcr3_values[i];
  38
  39         /* Safe fallback */
  40         return 5;
  41 }
  42
  43 static struct clk_ops sh4202_emi_clk_ops = {
  44         .recalc         = emi_clk_recalc,
  45 };
  46
  47 static struct clk sh4202_emi_clk = {
  48         .name           = "emi_clk",
  49         .flags          = CLK_ALWAYS_ENABLED,
  50         .ops            = &sh4202_emi_clk_ops,
  51 };
  52
  53 static void femi_clk_recalc(struct clk *clk)
  54 {
  55         int idx = (ctrl_inl(CPG2_FRQCR3) >> 3) & 0x0007;
  56         clk->rate = 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         .name           = "femi_clk",
  65         .flags          = CLK_ALWAYS_ENABLED,
  66         .ops            = &sh4202_femi_clk_ops,
  67 };
  68
  69 static void shoc_clk_init(struct clk *clk)
  70 {
  71         int i;
  72
  73         /*
  74          * For some reason, the shoc_clk seems to be set to some really
  75          * insane value at boot (values outside of the allowable frequency
  76          * range for instance). We deal with this by scaling it back down
  77          * to something sensible just in case.
  78          *
  79          * Start scaling from the high end down until we find something
  80          * that passes rate verification..
  81          */
  82         for (i = 0; i < ARRAY_SIZE(frqcr3_divisors); i++) {
  83                 int divisor = frqcr3_divisors[i];
  84
  85                 if (clk->ops->set_rate(clk, clk->parent->rate / divisor) == 0)
  86                         break;
  87         }
  88
  89         WARN_ON(i == ARRAY_SIZE(frqcr3_divisors));      /* Undefined clock */
  90 }
  91
  92 static void shoc_clk_recalc(struct clk *clk)
  93 {
  94         int idx = (ctrl_inl(CPG2_FRQCR3) >> 6) & 0x0007;
  95         clk->rate = clk->parent->rate / frqcr3_divisors[idx];
  96 }
  97
  98 static int shoc_clk_verify_rate(struct clk *clk, unsigned long rate)
  99 {
 100         struct clk *bclk = clk_get("bus_clk");
 101         unsigned long bclk_rate = clk_get_rate(bclk);
 102
 103         clk_put(bclk);
 104
 105         if (rate > bclk_rate)
 106                 return 1;
 107         if (rate > 66000000)
 108                 return 1;
 109
 110         return 0;
 111 }
 112
 113 static int shoc_clk_set_rate(struct clk *clk, unsigned long rate)
 114 {
 115         unsigned long frqcr3;
 116         unsigned int tmp;
 117
 118         /* Make sure we have something sensible to switch to */
 119         if (shoc_clk_verify_rate(clk, rate) != 0)
 120                 return -EINVAL;
 121
 122         tmp = frqcr3_lookup(clk, rate);
 123
 124         frqcr3 = ctrl_inl(CPG2_FRQCR3);
 125         frqcr3 &= ~(0x0007 << 6);
 126         frqcr3 |= tmp << 6;
 127         ctrl_outl(frqcr3, CPG2_FRQCR3);
 128
 129         clk->rate = clk->parent->rate / frqcr3_divisors[tmp];
 130
 131         return 0;
 132 }
 133
 134 static struct clk_ops sh4202_shoc_clk_ops = {
 135         .init           = shoc_clk_init,
 136         .recalc         = shoc_clk_recalc,
 137         .set_rate       = shoc_clk_set_rate,
 138 };
 139
 140 static struct clk sh4202_shoc_clk = {
 141         .name           = "shoc_clk",
 142         .flags          = CLK_ALWAYS_ENABLED,
 143         .ops            = &sh4202_shoc_clk_ops,
 144 };
 145
 146 static struct clk *sh4202_onchip_clocks[] = {
 147         &sh4202_emi_clk,
 148         &sh4202_femi_clk,
 149         &sh4202_shoc_clk,
 150 };
 151
 152 static int __init sh4202_clk_init(void)
 153 {
 154         struct clk *clk = clk_get("master_clk");
 155         int i;
 156
 157         for (i = 0; i < ARRAY_SIZE(sh4202_onchip_clocks); i++) {
 158                 struct clk *clkp = sh4202_onchip_clocks[i];
 159
 160                 clkp->parent = clk;
 161                 clk_register(clkp);
 162                 clk_enable(clkp);
 163         }
 164
 165         /*
 166          * Now that we have the rest of the clocks registered, we need to
 167          * force the parent clock to propagate so that these clocks will
 168          * automatically figure out their rate. We cheat by handing the
 169          * parent clock its current rate and forcing child propagation.
 170          */
 171         clk_set_rate(clk, clk_get_rate(clk));
 172
 173         clk_put(clk);
 174
 175         return 0;
 176 }
 177
 178 arch_initcall(sh4202_clk_init);
 179