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