drivers/clk/sunxi/clk-sun9i-cpus.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2015 Chen-Yu Tsai
   4  *
   5  * Chen-Yu Tsai <wens@csie.org>
   6  *
   7  * Allwinner A80 CPUS clock driver
   8  *
   9  */
  10
  11 #include <linux/clk.h>
  12 #include <linux/clk-provider.h>
  13 #include <linux/slab.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/of.h>
  16 #include <linux/of_address.h>
  17
  18 static DEFINE_SPINLOCK(sun9i_a80_cpus_lock);
  19
  20 /**
  21  * sun9i_a80_cpus_clk_setup() - Setup function for a80 cpus composite clk
  22  */
  23
  24 #define SUN9I_CPUS_MAX_PARENTS          4
  25 #define SUN9I_CPUS_MUX_PARENT_PLL4      3
  26 #define SUN9I_CPUS_MUX_SHIFT            16
  27 #define SUN9I_CPUS_MUX_MASK             GENMASK(17, 16)
  28 #define SUN9I_CPUS_MUX_GET_PARENT(reg)  ((reg & SUN9I_CPUS_MUX_MASK) >> \
  29                                                 SUN9I_CPUS_MUX_SHIFT)
  30
  31 #define SUN9I_CPUS_DIV_SHIFT            4
  32 #define SUN9I_CPUS_DIV_MASK             GENMASK(5, 4)
  33 #define SUN9I_CPUS_DIV_GET(reg)         ((reg & SUN9I_CPUS_DIV_MASK) >> \
  34                                                 SUN9I_CPUS_DIV_SHIFT)
  35 #define SUN9I_CPUS_DIV_SET(reg, div)    ((reg & ~SUN9I_CPUS_DIV_MASK) | \
  36                                                 (div << SUN9I_CPUS_DIV_SHIFT))
  37 #define SUN9I_CPUS_PLL4_DIV_SHIFT       8
  38 #define SUN9I_CPUS_PLL4_DIV_MASK        GENMASK(12, 8)
  39 #define SUN9I_CPUS_PLL4_DIV_GET(reg)    ((reg & SUN9I_CPUS_PLL4_DIV_MASK) >> \
  40                                                 SUN9I_CPUS_PLL4_DIV_SHIFT)
  41 #define SUN9I_CPUS_PLL4_DIV_SET(reg, div) ((reg & ~SUN9I_CPUS_PLL4_DIV_MASK) | \
  42                                                 (div << SUN9I_CPUS_PLL4_DIV_SHIFT))
  43
  44 struct sun9i_a80_cpus_clk {
  45         struct clk_hw hw;
  46         void __iomem *reg;
  47 };
  48
  49 #define to_sun9i_a80_cpus_clk(_hw) container_of(_hw, struct sun9i_a80_cpus_clk, hw)
  50
  51 static unsigned long sun9i_a80_cpus_clk_recalc_rate(struct clk_hw *hw,
  52                                                     unsigned long parent_rate)
  53 {
  54         struct sun9i_a80_cpus_clk *cpus = to_sun9i_a80_cpus_clk(hw);
  55         unsigned long rate;
  56         u32 reg;
  57
  58         /* Fetch the register value */
  59         reg = readl(cpus->reg);
  60
  61         /* apply pre-divider first if parent is pll4 */
  62         if (SUN9I_CPUS_MUX_GET_PARENT(reg) == SUN9I_CPUS_MUX_PARENT_PLL4)
  63                 parent_rate /= SUN9I_CPUS_PLL4_DIV_GET(reg) + 1;
  64
  65         /* clk divider */
  66         rate = parent_rate / (SUN9I_CPUS_DIV_GET(reg) + 1);
  67
  68         return rate;
  69 }
  70
  71 static long sun9i_a80_cpus_clk_round(unsigned long rate, u8 *divp, u8 *pre_divp,
  72                                      u8 parent, unsigned long parent_rate)
  73 {
  74         u8 div, pre_div = 1;
  75
  76         /*
  77          * clock can only divide, so we will never be able to achieve
  78          * frequencies higher than the parent frequency
  79          */
  80         if (parent_rate && rate > parent_rate)
  81                 rate = parent_rate;
  82
  83         div = DIV_ROUND_UP(parent_rate, rate);
  84
  85         /* calculate pre-divider if parent is pll4 */
  86         if (parent == SUN9I_CPUS_MUX_PARENT_PLL4 && div > 4) {
  87                 /* pre-divider is 1 ~ 32 */
  88                 if (div < 32) {
  89                         pre_div = div;
  90                         div = 1;
  91                 } else if (div < 64) {
  92                         pre_div = DIV_ROUND_UP(div, 2);
  93                         div = 2;
  94                 } else if (div < 96) {
  95                         pre_div = DIV_ROUND_UP(div, 3);
  96                         div = 3;
  97                 } else {
  98                         pre_div = DIV_ROUND_UP(div, 4);
  99                         div = 4;
 100                 }
 101         }
 102
 103         /* we were asked to pass back divider values */
 104         if (divp) {
 105                 *divp = div - 1;
 106                 *pre_divp = pre_div - 1;
 107         }
 108
 109         return parent_rate / pre_div / div;
 110 }
 111
 112 static int sun9i_a80_cpus_clk_determine_rate(struct clk_hw *clk,
 113                                              struct clk_rate_request *req)
 114 {
 115         struct clk_hw *parent, *best_parent = NULL;
 116         int i, num_parents;
 117         unsigned long parent_rate, best = 0, child_rate, best_child_rate = 0;
 118         unsigned long rate = req->rate;
 119
 120         /* find the parent that can help provide the fastest rate <= rate */
 121         num_parents = clk_hw_get_num_parents(clk);
 122         for (i = 0; i < num_parents; i++) {
 123                 parent = clk_hw_get_parent_by_index(clk, i);
 124                 if (!parent)
 125                         continue;
 126                 if (clk_hw_get_flags(clk) & CLK_SET_RATE_PARENT)
 127                         parent_rate = clk_hw_round_rate(parent, rate);
 128                 else
 129                         parent_rate = clk_hw_get_rate(parent);
 130
 131                 child_rate = sun9i_a80_cpus_clk_round(rate, NULL, NULL, i,
 132                                                       parent_rate);
 133
 134                 if (child_rate <= rate && child_rate > best_child_rate) {
 135                         best_parent = parent;
 136                         best = parent_rate;
 137                         best_child_rate = child_rate;
 138                 }
 139         }
 140
 141         if (!best_parent)
 142                 return -EINVAL;
 143
 144         req->best_parent_hw = best_parent;
 145         req->best_parent_rate = best;
 146         req->rate = best_child_rate;
 147
 148         return 0;
 149 }
 150
 151 static int sun9i_a80_cpus_clk_set_rate(struct clk_hw *hw, unsigned long rate,
 152                                        unsigned long parent_rate)
 153 {
 154         struct sun9i_a80_cpus_clk *cpus = to_sun9i_a80_cpus_clk(hw);
 155         unsigned long flags;
 156         u8 div, pre_div, parent;
 157         u32 reg;
 158
 159         spin_lock_irqsave(&sun9i_a80_cpus_lock, flags);
 160
 161         reg = readl(cpus->reg);
 162
 163         /* need to know which parent is used to apply pre-divider */
 164         parent = SUN9I_CPUS_MUX_GET_PARENT(reg);
 165         sun9i_a80_cpus_clk_round(rate, &div, &pre_div, parent, parent_rate);
 166
 167         reg = SUN9I_CPUS_DIV_SET(reg, div);
 168         reg = SUN9I_CPUS_PLL4_DIV_SET(reg, pre_div);
 169         writel(reg, cpus->reg);
 170
 171         spin_unlock_irqrestore(&sun9i_a80_cpus_lock, flags);
 172
 173         return 0;
 174 }
 175
 176 static const struct clk_ops sun9i_a80_cpus_clk_ops = {
 177         .determine_rate = sun9i_a80_cpus_clk_determine_rate,
 178         .recalc_rate    = sun9i_a80_cpus_clk_recalc_rate,
 179         .set_rate       = sun9i_a80_cpus_clk_set_rate,
 180 };
 181
 182 static void sun9i_a80_cpus_setup(struct device_node *node)
 183 {
 184         const char *clk_name = node->name;
 185         const char *parents[SUN9I_CPUS_MAX_PARENTS];
 186         struct resource res;
 187         struct sun9i_a80_cpus_clk *cpus;
 188         struct clk_mux *mux;
 189         struct clk *clk;
 190         int ret;
 191
 192         cpus = kzalloc(sizeof(*cpus), GFP_KERNEL);
 193         if (!cpus)
 194                 return;
 195
 196         cpus->reg = of_io_request_and_map(node, 0, of_node_full_name(node));
 197         if (IS_ERR(cpus->reg))
 198                 goto err_free_cpus;
 199
 200         of_property_read_string(node, "clock-output-names", &clk_name);
 201
 202         /* we have a mux, we will have >1 parents */
 203         ret = of_clk_parent_fill(node, parents, SUN9I_CPUS_MAX_PARENTS);
 204
 205         mux = kzalloc(sizeof(*mux), GFP_KERNEL);
 206         if (!mux)
 207                 goto err_unmap;
 208
 209         /* set up clock properties */
 210         mux->reg = cpus->reg;
 211         mux->shift = SUN9I_CPUS_MUX_SHIFT;
 212         /* un-shifted mask is what mux_clk expects */
 213         mux->mask = SUN9I_CPUS_MUX_MASK >> SUN9I_CPUS_MUX_SHIFT;
 214         mux->lock = &sun9i_a80_cpus_lock;
 215
 216         clk = clk_register_composite(NULL, clk_name, parents, ret,
 217                                      &mux->hw, &clk_mux_ops,
 218                                      &cpus->hw, &sun9i_a80_cpus_clk_ops,
 219                                      NULL, NULL, 0);
 220         if (IS_ERR(clk))
 221                 goto err_free_mux;
 222
 223         ret = of_clk_add_provider(node, of_clk_src_simple_get, clk);
 224         if (ret)
 225                 goto err_unregister;
 226
 227         return;
 228
 229 err_unregister:
 230         clk_unregister(clk);
 231 err_free_mux:
 232         kfree(mux);
 233 err_unmap:
 234         iounmap(cpus->reg);
 235         of_address_to_resource(node, 0, &res);
 236         release_mem_region(res.start, resource_size(&res));
 237 err_free_cpus:
 238         kfree(cpus);
 239 }
 240 CLK_OF_DECLARE(sun9i_a80_cpus, "allwinner,sun9i-a80-cpus-clk",
 241                sun9i_a80_cpus_setup);