drivers/clk/at91/clk-generated.c

   1 /*
   2  * Copyright (C) 2016 Atmel Corporation
   3  *               Wenyou.Yang <wenyou.yang@atmel.com>
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 #include <common.h>
   9 #include <clk-uclass.h>
  10 #include <dm.h>
  11 #include <linux/io.h>
  12 #include <mach/at91_pmc.h>
  13 #include "pmc.h"
  14
  15 DECLARE_GLOBAL_DATA_PTR;
  16
  17 #define GENERATED_SOURCE_MAX    6
  18 #define GENERATED_MAX_DIV       255
  19
  20 /**
  21  * generated_clk_bind() - for the generated clock driver
  22  * Recursively bind its children as clk devices.
  23  *
  24  * @return: 0 on success, or negative error code on failure
  25  */
  26 static int generated_clk_bind(struct udevice *dev)
  27 {
  28         return at91_clk_sub_device_bind(dev, "generic-clk");
  29 }
  30
  31 static const struct udevice_id generated_clk_match[] = {
  32         { .compatible = "atmel,sama5d2-clk-generated" },
  33         {}
  34 };
  35
  36 U_BOOT_DRIVER(generated_clk) = {
  37         .name = "generated-clk",
  38         .id = UCLASS_MISC,
  39         .of_match = generated_clk_match,
  40         .bind = generated_clk_bind,
  41 };
  42
  43 /*-------------------------------------------------------------*/
  44
  45 struct generic_clk_priv {
  46         u32 num_parents;
  47 };
  48
  49 static ulong generic_clk_get_rate(struct clk *clk)
  50 {
  51         struct pmc_platdata *plat = dev_get_platdata(clk->dev);
  52         struct at91_pmc *pmc = plat->reg_base;
  53         struct clk parent;
  54         ulong clk_rate;
  55         u32 tmp, gckdiv;
  56         u8 clock_source, parent_index;
  57         int ret;
  58
  59         writel(clk->id & AT91_PMC_PCR_PID_MASK, &pmc->pcr);
  60         tmp = readl(&pmc->pcr);
  61         clock_source = (tmp >> AT91_PMC_PCR_GCKCSS_OFFSET) &
  62                     AT91_PMC_PCR_GCKCSS_MASK;
  63         gckdiv = (tmp >> AT91_PMC_PCR_GCKDIV_OFFSET) & AT91_PMC_PCR_GCKDIV_MASK;
  64
  65         parent_index = clock_source - 1;
  66         ret = clk_get_by_index(dev_get_parent(clk->dev), parent_index, &parent);
  67         if (ret)
  68                 return 0;
  69
  70         clk_rate = clk_get_rate(&parent) / (gckdiv + 1);
  71
  72         clk_free(&parent);
  73
  74         return clk_rate;
  75 }
  76
  77 static ulong generic_clk_set_rate(struct clk *clk, ulong rate)
  78 {
  79         struct pmc_platdata *plat = dev_get_platdata(clk->dev);
  80         struct at91_pmc *pmc = plat->reg_base;
  81         struct generic_clk_priv *priv = dev_get_priv(clk->dev);
  82         struct clk parent, best_parent;
  83         ulong tmp_rate, best_rate = rate, parent_rate;
  84         int tmp_diff, best_diff = -1;
  85         u32 div, best_div = 0;
  86         u8 best_parent_index, best_clock_source = 0;
  87         u8 i;
  88         u32 tmp;
  89         int ret;
  90
  91         for (i = 0; i < priv->num_parents; i++) {
  92                 ret = clk_get_by_index(dev_get_parent(clk->dev), i, &parent);
  93                 if (ret)
  94                         return ret;
  95
  96                 parent_rate = clk_get_rate(&parent);
  97                 if (IS_ERR_VALUE(parent_rate))
  98                         return parent_rate;
  99
 100                 for (div = 1; div < GENERATED_MAX_DIV + 2; div++) {
 101                         tmp_rate = DIV_ROUND_CLOSEST(parent_rate, div);
 102                         tmp_diff = abs(rate - tmp_rate);
 103
 104                         if (best_diff < 0 || best_diff > tmp_diff) {
 105                                 best_rate = tmp_rate;
 106                                 best_diff = tmp_diff;
 107
 108                                 best_div = div - 1;
 109                                 best_parent = parent;
 110                                 best_parent_index = i;
 111                                 best_clock_source = best_parent_index + 1;
 112                         }
 113
 114                         if (!best_diff || tmp_rate < rate)
 115                                 break;
 116                 }
 117
 118                 if (!best_diff)
 119                         break;
 120         }
 121
 122         debug("GCK: best parent: %s, best_rate = %ld, best_div = %d\n",
 123               best_parent.dev->name, best_rate, best_div);
 124
 125         ret = clk_enable(&best_parent);
 126         if (ret)
 127                 return ret;
 128
 129         writel(clk->id & AT91_PMC_PCR_PID_MASK, &pmc->pcr);
 130         tmp = readl(&pmc->pcr);
 131         tmp &= ~(AT91_PMC_PCR_GCKDIV | AT91_PMC_PCR_GCKCSS);
 132         tmp |= AT91_PMC_PCR_GCKCSS_(best_clock_source) |
 133                AT91_PMC_PCR_CMD_WRITE |
 134                AT91_PMC_PCR_GCKDIV_(best_div) |
 135                AT91_PMC_PCR_GCKEN;
 136         writel(tmp, &pmc->pcr);
 137
 138         while (!(readl(&pmc->sr) & AT91_PMC_GCKRDY))
 139                 ;
 140
 141         return 0;
 142 }
 143
 144 static struct clk_ops generic_clk_ops = {
 145         .of_xlate = at91_clk_of_xlate,
 146         .get_rate = generic_clk_get_rate,
 147         .set_rate = generic_clk_set_rate,
 148 };
 149
 150 static int generic_clk_ofdata_to_platdata(struct udevice *dev)
 151 {
 152         struct generic_clk_priv *priv = dev_get_priv(dev);
 153         u32 cells[GENERATED_SOURCE_MAX];
 154         u32 num_parents;
 155
 156         num_parents = fdtdec_get_int_array_count(gd->fdt_blob,
 157                         dev_of_offset(dev_get_parent(dev)), "clocks", cells,
 158                         GENERATED_SOURCE_MAX);
 159
 160         if (!num_parents)
 161                 return -1;
 162
 163         priv->num_parents = num_parents;
 164
 165         return 0;
 166 }
 167
 168 U_BOOT_DRIVER(generic_clk) = {
 169         .name = "generic-clk",
 170         .id = UCLASS_CLK,
 171         .probe = at91_clk_probe,
 172         .ofdata_to_platdata = generic_clk_ofdata_to_platdata,
 173         .priv_auto_alloc_size = sizeof(struct generic_clk_priv),
 174         .platdata_auto_alloc_size = sizeof(struct pmc_platdata),
 175         .ops = &generic_clk_ops,
 176 };