drivers/clk/ti/dpll44xx.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * OMAP4-specific DPLL control functions
   4  *
   5  * Copyright (C) 2011 Texas Instruments, Inc.
   6  * Rajendra Nayak
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/errno.h>
  11 #include <linux/clk.h>
  12 #include <linux/io.h>
  13 #include <linux/bitops.h>
  14 #include <linux/clk/ti.h>
  15
  16 #include "clock.h"
  17
  18 /*
  19  * Maximum DPLL input frequency (FINT) and output frequency (FOUT) that
  20  * can supported when using the DPLL low-power mode. Frequencies are
  21  * defined in OMAP4430/60 Public TRM section 3.6.3.3.2 "Enable Control,
  22  * Status, and Low-Power Operation Mode".
  23  */
  24 #define OMAP4_DPLL_LP_FINT_MAX  1000000
  25 #define OMAP4_DPLL_LP_FOUT_MAX  100000000
  26
  27 /*
  28  * Bitfield declarations
  29  */
  30 #define OMAP4430_DPLL_CLKOUT_GATE_CTRL_MASK             BIT(8)
  31 #define OMAP4430_DPLL_CLKOUTX2_GATE_CTRL_MASK           BIT(10)
  32 #define OMAP4430_DPLL_REGM4XEN_MASK                     BIT(11)
  33
  34 /* Static rate multiplier for OMAP4 REGM4XEN clocks */
  35 #define OMAP4430_REGM4XEN_MULT                          4
  36
  37 static void omap4_dpllmx_allow_gatectrl(struct clk_hw_omap *clk)
  38 {
  39         u32 v;
  40         u32 mask;
  41
  42         if (!clk)
  43                 return;
  44
  45         mask = clk->flags & CLOCK_CLKOUTX2 ?
  46                         OMAP4430_DPLL_CLKOUTX2_GATE_CTRL_MASK :
  47                         OMAP4430_DPLL_CLKOUT_GATE_CTRL_MASK;
  48
  49         v = ti_clk_ll_ops->clk_readl(&clk->clksel_reg);
  50         /* Clear the bit to allow gatectrl */
  51         v &= ~mask;
  52         ti_clk_ll_ops->clk_writel(v, &clk->clksel_reg);
  53 }
  54
  55 static void omap4_dpllmx_deny_gatectrl(struct clk_hw_omap *clk)
  56 {
  57         u32 v;
  58         u32 mask;
  59
  60         if (!clk)
  61                 return;
  62
  63         mask = clk->flags & CLOCK_CLKOUTX2 ?
  64                         OMAP4430_DPLL_CLKOUTX2_GATE_CTRL_MASK :
  65                         OMAP4430_DPLL_CLKOUT_GATE_CTRL_MASK;
  66
  67         v = ti_clk_ll_ops->clk_readl(&clk->clksel_reg);
  68         /* Set the bit to deny gatectrl */
  69         v |= mask;
  70         ti_clk_ll_ops->clk_writel(v, &clk->clksel_reg);
  71 }
  72
  73 const struct clk_hw_omap_ops clkhwops_omap4_dpllmx = {
  74         .allow_idle     = omap4_dpllmx_allow_gatectrl,
  75         .deny_idle      = omap4_dpllmx_deny_gatectrl,
  76 };
  77
  78 /**
  79  * omap4_dpll_lpmode_recalc - compute DPLL low-power setting
  80  * @dd: pointer to the dpll data structure
  81  *
  82  * Calculates if low-power mode can be enabled based upon the last
  83  * multiplier and divider values calculated. If low-power mode can be
  84  * enabled, then the bit to enable low-power mode is stored in the
  85  * last_rounded_lpmode variable. This implementation is based upon the
  86  * criteria for enabling low-power mode as described in the OMAP4430/60
  87  * Public TRM section 3.6.3.3.2 "Enable Control, Status, and Low-Power
  88  * Operation Mode".
  89  */
  90 static void omap4_dpll_lpmode_recalc(struct dpll_data *dd)
  91 {
  92         long fint, fout;
  93
  94         fint = clk_hw_get_rate(dd->clk_ref) / (dd->last_rounded_n + 1);
  95         fout = fint * dd->last_rounded_m;
  96
  97         if ((fint < OMAP4_DPLL_LP_FINT_MAX) && (fout < OMAP4_DPLL_LP_FOUT_MAX))
  98                 dd->last_rounded_lpmode = 1;
  99         else
 100                 dd->last_rounded_lpmode = 0;
 101 }
 102
 103 /**
 104  * omap4_dpll_regm4xen_recalc - compute DPLL rate, considering REGM4XEN bit
 105  * @clk: struct clk * of the DPLL to compute the rate for
 106  *
 107  * Compute the output rate for the OMAP4 DPLL represented by @clk.
 108  * Takes the REGM4XEN bit into consideration, which is needed for the
 109  * OMAP4 ABE DPLL.  Returns the DPLL's output rate (before M-dividers)
 110  * upon success, or 0 upon error.
 111  */
 112 unsigned long omap4_dpll_regm4xen_recalc(struct clk_hw *hw,
 113                                          unsigned long parent_rate)
 114 {
 115         struct clk_hw_omap *clk = to_clk_hw_omap(hw);
 116         u32 v;
 117         unsigned long rate;
 118         struct dpll_data *dd;
 119
 120         if (!clk || !clk->dpll_data)
 121                 return 0;
 122
 123         dd = clk->dpll_data;
 124
 125         rate = omap2_get_dpll_rate(clk);
 126
 127         /* regm4xen adds a multiplier of 4 to DPLL calculations */
 128         v = ti_clk_ll_ops->clk_readl(&dd->control_reg);
 129         if (v & OMAP4430_DPLL_REGM4XEN_MASK)
 130                 rate *= OMAP4430_REGM4XEN_MULT;
 131
 132         return rate;
 133 }
 134
 135 /**
 136  * omap4_dpll_regm4xen_round_rate - round DPLL rate, considering REGM4XEN bit
 137  * @clk: struct clk * of the DPLL to round a rate for
 138  * @target_rate: the desired rate of the DPLL
 139  *
 140  * Compute the rate that would be programmed into the DPLL hardware
 141  * for @clk if set_rate() were to be provided with the rate
 142  * @target_rate.  Takes the REGM4XEN bit into consideration, which is
 143  * needed for the OMAP4 ABE DPLL.  Returns the rounded rate (before
 144  * M-dividers) upon success, -EINVAL if @clk is null or not a DPLL, or
 145  * ~0 if an error occurred in omap2_dpll_round_rate().
 146  */
 147 long omap4_dpll_regm4xen_round_rate(struct clk_hw *hw,
 148                                     unsigned long target_rate,
 149                                     unsigned long *parent_rate)
 150 {
 151         struct clk_hw_omap *clk = to_clk_hw_omap(hw);
 152         struct dpll_data *dd;
 153         long r;
 154
 155         if (!clk || !clk->dpll_data)
 156                 return -EINVAL;
 157
 158         dd = clk->dpll_data;
 159
 160         dd->last_rounded_m4xen = 0;
 161
 162         /*
 163          * First try to compute the DPLL configuration for
 164          * target rate without using the 4X multiplier.
 165          */
 166         r = omap2_dpll_round_rate(hw, target_rate, NULL);
 167         if (r != ~0)
 168                 goto out;
 169
 170         /*
 171          * If we did not find a valid DPLL configuration, try again, but
 172          * this time see if using the 4X multiplier can help. Enabling the
 173          * 4X multiplier is equivalent to dividing the target rate by 4.
 174          */
 175         r = omap2_dpll_round_rate(hw, target_rate / OMAP4430_REGM4XEN_MULT,
 176                                   NULL);
 177         if (r == ~0)
 178                 return r;
 179
 180         dd->last_rounded_rate *= OMAP4430_REGM4XEN_MULT;
 181         dd->last_rounded_m4xen = 1;
 182
 183 out:
 184         omap4_dpll_lpmode_recalc(dd);
 185
 186         return dd->last_rounded_rate;
 187 }
 188
 189 /**
 190  * omap4_dpll_regm4xen_determine_rate - determine rate for a DPLL
 191  * @hw: pointer to the clock to determine rate for
 192  * @req: target rate request
 193  *
 194  * Determines which DPLL mode to use for reaching a desired rate.
 195  * Checks whether the DPLL shall be in bypass or locked mode, and if
 196  * locked, calculates the M,N values for the DPLL via round-rate.
 197  * Returns 0 on success and a negative error value otherwise.
 198  */
 199 int omap4_dpll_regm4xen_determine_rate(struct clk_hw *hw,
 200                                        struct clk_rate_request *req)
 201 {
 202         struct clk_hw_omap *clk = to_clk_hw_omap(hw);
 203         struct dpll_data *dd;
 204
 205         if (!req->rate)
 206                 return -EINVAL;
 207
 208         dd = clk->dpll_data;
 209         if (!dd)
 210                 return -EINVAL;
 211
 212         if (clk_hw_get_rate(dd->clk_bypass) == req->rate &&
 213             (dd->modes & (1 << DPLL_LOW_POWER_BYPASS))) {
 214                 req->best_parent_hw = dd->clk_bypass;
 215         } else {
 216                 req->rate = omap4_dpll_regm4xen_round_rate(hw, req->rate,
 217                                                 &req->best_parent_rate);
 218                 req->best_parent_hw = dd->clk_ref;
 219         }
 220
 221         req->best_parent_rate = req->rate;
 222
 223         return 0;
 224 }