drivers/clk/sunxi-ng/ccu_common.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright 2016 Maxime Ripard
   4  *
   5  * Maxime Ripard <maxime.ripard@free-electrons.com>
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/clk-provider.h>
  10 #include <linux/device.h>
  11 #include <linux/iopoll.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14
  15 #include "ccu_common.h"
  16 #include "ccu_gate.h"
  17 #include "ccu_reset.h"
  18
  19 struct sunxi_ccu {
  20         const struct sunxi_ccu_desc     *desc;
  21         spinlock_t                      lock;
  22         struct ccu_reset                reset;
  23 };
  24
  25 void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock)
  26 {
  27         void __iomem *addr;
  28         u32 reg;
  29
  30         if (!lock)
  31                 return;
  32
  33         if (common->features & CCU_FEATURE_LOCK_REG)
  34                 addr = common->base + common->lock_reg;
  35         else
  36                 addr = common->base + common->reg;
  37
  38         WARN_ON(readl_relaxed_poll_timeout(addr, reg, reg & lock, 100, 70000));
  39 }
  40 EXPORT_SYMBOL_NS_GPL(ccu_helper_wait_for_lock, "SUNXI_CCU");
  41
  42 bool ccu_is_better_rate(struct ccu_common *common,
  43                         unsigned long target_rate,
  44                         unsigned long current_rate,
  45                         unsigned long best_rate)
  46 {
  47         unsigned long min_rate, max_rate;
  48
  49         clk_hw_get_rate_range(&common->hw, &min_rate, &max_rate);
  50
  51         if (current_rate > max_rate)
  52                 return false;
  53
  54         if (current_rate < min_rate)
  55                 return false;
  56
  57         if (common->features & CCU_FEATURE_CLOSEST_RATE)
  58                 return abs(current_rate - target_rate) < abs(best_rate - target_rate);
  59
  60         return current_rate <= target_rate && current_rate > best_rate;
  61 }
  62 EXPORT_SYMBOL_NS_GPL(ccu_is_better_rate, "SUNXI_CCU");
  63
  64 /*
  65  * This clock notifier is called when the frequency of a PLL clock is
  66  * changed. In common PLL designs, changes to the dividers take effect
  67  * almost immediately, while changes to the multipliers (implemented
  68  * as dividers in the feedback loop) take a few cycles to work into
  69  * the feedback loop for the PLL to stablize.
  70  *
  71  * Sometimes when the PLL clock rate is changed, the decrease in the
  72  * divider is too much for the decrease in the multiplier to catch up.
  73  * The PLL clock rate will spike, and in some cases, might lock up
  74  * completely.
  75  *
  76  * This notifier callback will gate and then ungate the clock,
  77  * effectively resetting it, so it proceeds to work. Care must be
  78  * taken to reparent consumers to other temporary clocks during the
  79  * rate change, and that this notifier callback must be the first
  80  * to be registered.
  81  */
  82 static int ccu_pll_notifier_cb(struct notifier_block *nb,
  83                                unsigned long event, void *data)
  84 {
  85         struct ccu_pll_nb *pll = to_ccu_pll_nb(nb);
  86         int ret = 0;
  87
  88         if (event != POST_RATE_CHANGE)
  89                 goto out;
  90
  91         ccu_gate_helper_disable(pll->common, pll->enable);
  92
  93         ret = ccu_gate_helper_enable(pll->common, pll->enable);
  94         if (ret)
  95                 goto out;
  96
  97         ccu_helper_wait_for_lock(pll->common, pll->lock);
  98
  99 out:
 100         return notifier_from_errno(ret);
 101 }
 102
 103 int ccu_pll_notifier_register(struct ccu_pll_nb *pll_nb)
 104 {
 105         pll_nb->clk_nb.notifier_call = ccu_pll_notifier_cb;
 106
 107         return clk_notifier_register(pll_nb->common->hw.clk,
 108                                      &pll_nb->clk_nb);
 109 }
 110 EXPORT_SYMBOL_NS_GPL(ccu_pll_notifier_register, "SUNXI_CCU");
 111
 112 static int sunxi_ccu_probe(struct sunxi_ccu *ccu, struct device *dev,
 113                            struct device_node *node, void __iomem *reg,
 114                            const struct sunxi_ccu_desc *desc)
 115 {
 116         struct ccu_reset *reset;
 117         int i, ret;
 118
 119         ccu->desc = desc;
 120
 121         spin_lock_init(&ccu->lock);
 122
 123         for (i = 0; i < desc->num_ccu_clks; i++) {
 124                 struct ccu_common *cclk = desc->ccu_clks[i];
 125
 126                 if (!cclk)
 127                         continue;
 128
 129                 cclk->base = reg;
 130                 cclk->lock = &ccu->lock;
 131         }
 132
 133         for (i = 0; i < desc->hw_clks->num ; i++) {
 134                 struct clk_hw *hw = desc->hw_clks->hws[i];
 135                 const char *name;
 136
 137                 if (!hw)
 138                         continue;
 139
 140                 name = hw->init->name;
 141                 if (dev)
 142                         ret = clk_hw_register(dev, hw);
 143                 else
 144                         ret = of_clk_hw_register(node, hw);
 145                 if (ret) {
 146                         pr_err("Couldn't register clock %d - %s\n", i, name);
 147                         goto err_clk_unreg;
 148                 }
 149         }
 150
 151         for (i = 0; i < desc->num_ccu_clks; i++) {
 152                 struct ccu_common *cclk = desc->ccu_clks[i];
 153
 154                 if (!cclk)
 155                         continue;
 156
 157                 if (cclk->max_rate)
 158                         clk_hw_set_rate_range(&cclk->hw, cclk->min_rate,
 159                                               cclk->max_rate);
 160                 else
 161                         WARN(cclk->min_rate,
 162                              "No max_rate, ignoring min_rate of clock %d - %s\n",
 163                              i, clk_hw_get_name(&cclk->hw));
 164         }
 165
 166         ret = of_clk_add_hw_provider(node, of_clk_hw_onecell_get,
 167                                      desc->hw_clks);
 168         if (ret)
 169                 goto err_clk_unreg;
 170
 171         reset = &ccu->reset;
 172         reset->rcdev.of_node = node;
 173         reset->rcdev.ops = &ccu_reset_ops;
 174         reset->rcdev.owner = dev ? dev->driver->owner : THIS_MODULE;
 175         reset->rcdev.nr_resets = desc->num_resets;
 176         reset->base = reg;
 177         reset->lock = &ccu->lock;
 178         reset->reset_map = desc->resets;
 179
 180         ret = reset_controller_register(&reset->rcdev);
 181         if (ret)
 182                 goto err_del_provider;
 183
 184         return 0;
 185
 186 err_del_provider:
 187         of_clk_del_provider(node);
 188 err_clk_unreg:
 189         while (--i >= 0) {
 190                 struct clk_hw *hw = desc->hw_clks->hws[i];
 191
 192                 if (!hw)
 193                         continue;
 194                 clk_hw_unregister(hw);
 195         }
 196         return ret;
 197 }
 198
 199 static void devm_sunxi_ccu_release(struct device *dev, void *res)
 200 {
 201         struct sunxi_ccu *ccu = res;
 202         const struct sunxi_ccu_desc *desc = ccu->desc;
 203         int i;
 204
 205         reset_controller_unregister(&ccu->reset.rcdev);
 206         of_clk_del_provider(dev->of_node);
 207
 208         for (i = 0; i < desc->hw_clks->num; i++) {
 209                 struct clk_hw *hw = desc->hw_clks->hws[i];
 210
 211                 if (!hw)
 212                         continue;
 213                 clk_hw_unregister(hw);
 214         }
 215 }
 216
 217 int devm_sunxi_ccu_probe(struct device *dev, void __iomem *reg,
 218                          const struct sunxi_ccu_desc *desc)
 219 {
 220         struct sunxi_ccu *ccu;
 221         int ret;
 222
 223         ccu = devres_alloc(devm_sunxi_ccu_release, sizeof(*ccu), GFP_KERNEL);
 224         if (!ccu)
 225                 return -ENOMEM;
 226
 227         ret = sunxi_ccu_probe(ccu, dev, dev->of_node, reg, desc);
 228         if (ret) {
 229                 devres_free(ccu);
 230                 return ret;
 231         }
 232
 233         devres_add(dev, ccu);
 234
 235         return 0;
 236 }
 237 EXPORT_SYMBOL_NS_GPL(devm_sunxi_ccu_probe, "SUNXI_CCU");
 238
 239 void of_sunxi_ccu_probe(struct device_node *node, void __iomem *reg,
 240                         const struct sunxi_ccu_desc *desc)
 241 {
 242         struct sunxi_ccu *ccu;
 243         int ret;
 244
 245         ccu = kzalloc(sizeof(*ccu), GFP_KERNEL);
 246         if (!ccu)
 247                 return;
 248
 249         ret = sunxi_ccu_probe(ccu, NULL, node, reg, desc);
 250         if (ret) {
 251                 pr_err("%pOF: probing clocks failed: %d\n", node, ret);
 252                 kfree(ccu);
 253         }
 254 }
 255
 256 MODULE_DESCRIPTION("Common clock support for Allwinner SoCs");
 257 MODULE_LICENSE("GPL");