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

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