arch/arm/mach-omap2/dpll44xx.c

   1 /*
   2  * OMAP4-specific DPLL control functions
   3  *
   4  * Copyright (C) 2011 Texas Instruments, Inc.
   5  * Rajendra Nayak
   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/kernel.h>
  13 #include <linux/errno.h>
  14 #include <linux/clk.h>
  15 #include <linux/io.h>
  16 #include <linux/bitops.h>
  17
  18 #include "soc.h"
  19 #include "clock.h"
  20 #include "clock44xx.h"
  21 #include "cm-regbits-44xx.h"
  22
  23 /*
  24  * Maximum DPLL input frequency (FINT) and output frequency (FOUT) that
  25  * can supported when using the DPLL low-power mode. Frequencies are
  26  * defined in OMAP4430/60 Public TRM section 3.6.3.3.2 "Enable Control,
  27  * Status, and Low-Power Operation Mode".
  28  */
  29 #define OMAP4_DPLL_LP_FINT_MAX  1000000
  30 #define OMAP4_DPLL_LP_FOUT_MAX  100000000
  31
  32 /* Supported only on OMAP4 */
  33 int omap4_dpllmx_gatectrl_read(struct clk_hw_omap *clk)
  34 {
  35         u32 v;
  36         u32 mask;
  37
  38         if (!clk || !clk->clksel_reg || !cpu_is_omap44xx())
  39                 return -EINVAL;
  40
  41         mask = clk->flags & CLOCK_CLKOUTX2 ?
  42                         OMAP4430_DPLL_CLKOUTX2_GATE_CTRL_MASK :
  43                         OMAP4430_DPLL_CLKOUT_GATE_CTRL_MASK;
  44
  45         v = omap2_clk_readl(clk, clk->clksel_reg);
  46         v &= mask;
  47         v >>= __ffs(mask);
  48
  49         return v;
  50 }
  51
  52 void omap4_dpllmx_allow_gatectrl(struct clk_hw_omap *clk)
  53 {
  54         u32 v;
  55         u32 mask;
  56
  57         if (!clk || !clk->clksel_reg || !cpu_is_omap44xx())
  58                 return;
  59
  60         mask = clk->flags & CLOCK_CLKOUTX2 ?
  61                         OMAP4430_DPLL_CLKOUTX2_GATE_CTRL_MASK :
  62                         OMAP4430_DPLL_CLKOUT_GATE_CTRL_MASK;
  63
  64         v = omap2_clk_readl(clk, clk->clksel_reg);
  65         /* Clear the bit to allow gatectrl */
  66         v &= ~mask;
  67         omap2_clk_writel(v, clk, clk->clksel_reg);
  68 }
  69
  70 void omap4_dpllmx_deny_gatectrl(struct clk_hw_omap *clk)
  71 {
  72         u32 v;
  73         u32 mask;
  74
  75         if (!clk || !clk->clksel_reg || !cpu_is_omap44xx())
  76                 return;
  77
  78         mask = clk->flags & CLOCK_CLKOUTX2 ?
  79                         OMAP4430_DPLL_CLKOUTX2_GATE_CTRL_MASK :
  80                         OMAP4430_DPLL_CLKOUT_GATE_CTRL_MASK;
  81
  82         v = omap2_clk_readl(clk, clk->clksel_reg);
  83         /* Set the bit to deny gatectrl */
  84         v |= mask;
  85         omap2_clk_writel(v, clk, clk->clksel_reg);
  86 }
  87
  88 const struct clk_hw_omap_ops clkhwops_omap4_dpllmx = {
  89         .allow_idle     = omap4_dpllmx_allow_gatectrl,
  90         .deny_idle      = omap4_dpllmx_deny_gatectrl,
  91 };
  92
  93 /**
  94  * omap4_dpll_lpmode_recalc - compute DPLL low-power setting
  95  * @dd: pointer to the dpll data structure
  96  *
  97  * Calculates if low-power mode can be enabled based upon the last
  98  * multiplier and divider values calculated. If low-power mode can be
  99  * enabled, then the bit to enable low-power mode is stored in the
 100  * last_rounded_lpmode variable. This implementation is based upon the
 101  * criteria for enabling low-power mode as described in the OMAP4430/60
 102  * Public TRM section 3.6.3.3.2 "Enable Control, Status, and Low-Power
 103  * Operation Mode".
 104  */
 105 static void omap4_dpll_lpmode_recalc(struct dpll_data *dd)
 106 {
 107         long fint, fout;
 108
 109         fint = __clk_get_rate(dd->clk_ref) / (dd->last_rounded_n + 1);
 110         fout = fint * dd->last_rounded_m;
 111
 112         if ((fint < OMAP4_DPLL_LP_FINT_MAX) && (fout < OMAP4_DPLL_LP_FOUT_MAX))
 113                 dd->last_rounded_lpmode = 1;
 114         else
 115                 dd->last_rounded_lpmode = 0;
 116 }
 117
 118 /**
 119  * omap4_dpll_regm4xen_recalc - compute DPLL rate, considering REGM4XEN bit
 120  * @clk: struct clk * of the DPLL to compute the rate for
 121  *
 122  * Compute the output rate for the OMAP4 DPLL represented by @clk.
 123  * Takes the REGM4XEN bit into consideration, which is needed for the
 124  * OMAP4 ABE DPLL.  Returns the DPLL's output rate (before M-dividers)
 125  * upon success, or 0 upon error.
 126  */
 127 unsigned long omap4_dpll_regm4xen_recalc(struct clk_hw *hw,
 128                         unsigned long parent_rate)
 129 {
 130         struct clk_hw_omap *clk = to_clk_hw_omap(hw);
 131         u32 v;
 132         unsigned long rate;
 133         struct dpll_data *dd;
 134
 135         if (!clk || !clk->dpll_data)
 136                 return 0;
 137
 138         dd = clk->dpll_data;
 139
 140         rate = omap2_get_dpll_rate(clk);
 141
 142         /* regm4xen adds a multiplier of 4 to DPLL calculations */
 143         v = omap2_clk_readl(clk, dd->control_reg);
 144         if (v & OMAP4430_DPLL_REGM4XEN_MASK)
 145                 rate *= OMAP4430_REGM4XEN_MULT;
 146
 147         return rate;
 148 }
 149
 150 /**
 151  * omap4_dpll_regm4xen_round_rate - round DPLL rate, considering REGM4XEN bit
 152  * @clk: struct clk * of the DPLL to round a rate for
 153  * @target_rate: the desired rate of the DPLL
 154  *
 155  * Compute the rate that would be programmed into the DPLL hardware
 156  * for @clk if set_rate() were to be provided with the rate
 157  * @target_rate.  Takes the REGM4XEN bit into consideration, which is
 158  * needed for the OMAP4 ABE DPLL.  Returns the rounded rate (before
 159  * M-dividers) upon success, -EINVAL if @clk is null or not a DPLL, or
 160  * ~0 if an error occurred in omap2_dpll_round_rate().
 161  */
 162 long omap4_dpll_regm4xen_round_rate(struct clk_hw *hw,
 163                                     unsigned long target_rate,
 164                                     unsigned long *parent_rate)
 165 {
 166         struct clk_hw_omap *clk = to_clk_hw_omap(hw);
 167         struct dpll_data *dd;
 168         long r;
 169
 170         if (!clk || !clk->dpll_data)
 171                 return -EINVAL;
 172
 173         dd = clk->dpll_data;
 174
 175         dd->last_rounded_m4xen = 0;
 176
 177         /*
 178          * First try to compute the DPLL configuration for
 179          * target rate without using the 4X multiplier.
 180          */
 181         r = omap2_dpll_round_rate(hw, target_rate, NULL);
 182         if (r != ~0)
 183                 goto out;
 184
 185         /*
 186          * If we did not find a valid DPLL configuration, try again, but
 187          * this time see if using the 4X multiplier can help. Enabling the
 188          * 4X multiplier is equivalent to dividing the target rate by 4.
 189          */
 190         r = omap2_dpll_round_rate(hw, target_rate / OMAP4430_REGM4XEN_MULT,
 191                                   NULL);
 192         if (r == ~0)
 193                 return r;
 194
 195         dd->last_rounded_rate *= OMAP4430_REGM4XEN_MULT;
 196         dd->last_rounded_m4xen = 1;
 197
 198 out:
 199         omap4_dpll_lpmode_recalc(dd);
 200
 201         return dd->last_rounded_rate;
 202 }