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         if (common->features & CCU_FEATURE_CLOSEST_RATE)
  48                 return abs(current_rate - target_rate) < abs(best_rate - target_rate);
  49
  50         return current_rate <= target_rate && current_rate > best_rate;
  51 }
  52 EXPORT_SYMBOL_NS_GPL(ccu_is_better_rate, SUNXI_CCU);
  53
  54 /*
  55  * This clock notifier is called when the frequency of a PLL clock is
  56  * changed. In common PLL designs, changes to the dividers take effect
  57  * almost immediately, while changes to the multipliers (implemented
  58  * as dividers in the feedback loop) take a few cycles to work into
  59  * the feedback loop for the PLL to stablize.
  60  *
  61  * Sometimes when the PLL clock rate is changed, the decrease in the
  62  * divider is too much for the decrease in the multiplier to catch up.
  63  * The PLL clock rate will spike, and in some cases, might lock up
  64  * completely.
  65  *
  66  * This notifier callback will gate and then ungate the clock,
  67  * effectively resetting it, so it proceeds to work. Care must be
  68  * taken to reparent consumers to other temporary clocks during the
  69  * rate change, and that this notifier callback must be the first
  70  * to be registered.
  71  */
  72 static int ccu_pll_notifier_cb(struct notifier_block *nb,
  73                                unsigned long event, void *data)
  74 {
  75         struct ccu_pll_nb *pll = to_ccu_pll_nb(nb);
  76         int ret = 0;
  77
  78         if (event != POST_RATE_CHANGE)
  79                 goto out;
  80
  81         ccu_gate_helper_disable(pll->common, pll->enable);
  82
  83         ret = ccu_gate_helper_enable(pll->common, pll->enable);
  84         if (ret)
  85                 goto out;
  86
  87         ccu_helper_wait_for_lock(pll->common, pll->lock);
  88
  89 out:
  90         return notifier_from_errno(ret);
  91 }
  92
  93 int ccu_pll_notifier_register(struct ccu_pll_nb *pll_nb)
  94 {
  95         pll_nb->clk_nb.notifier_call = ccu_pll_notifier_cb;
  96
  97         return clk_notifier_register(pll_nb->common->hw.clk,
  98                                      &pll_nb->clk_nb);
  99 }
 100 EXPORT_SYMBOL_NS_GPL(ccu_pll_notifier_register, SUNXI_CCU);
 101
 102 static int sunxi_ccu_probe(struct sunxi_ccu *ccu, struct device *dev,
 103                            struct device_node *node, void __iomem *reg,
 104                            const struct sunxi_ccu_desc *desc)
 105 {
 106         struct ccu_reset *reset;
 107         int i, ret;
 108
 109         ccu->desc = desc;
 110
 111         spin_lock_init(&ccu->lock);
 112
 113         for (i = 0; i < desc->num_ccu_clks; i++) {
 114                 struct ccu_common *cclk = desc->ccu_clks[i];
 115
 116                 if (!cclk)
 117                         continue;
 118
 119                 cclk->base = reg;
 120                 cclk->lock = &ccu->lock;
 121         }
 122
 123         for (i = 0; i < desc->hw_clks->num ; i++) {
 124                 struct clk_hw *hw = desc->hw_clks->hws[i];
 125                 const char *name;
 126
 127                 if (!hw)
 128                         continue;
 129
 130                 name = hw->init->name;
 131                 if (dev)
 132                         ret = clk_hw_register(dev, hw);
 133                 else
 134                         ret = of_clk_hw_register(node, hw);
 135                 if (ret) {
 136                         pr_err("Couldn't register clock %d - %s\n", i, name);
 137                         goto err_clk_unreg;
 138                 }
 139         }
 140
 141         ret = of_clk_add_hw_provider(node, of_clk_hw_onecell_get,
 142                                      desc->hw_clks);
 143         if (ret)
 144                 goto err_clk_unreg;
 145
 146         reset = &ccu->reset;
 147         reset->rcdev.of_node = node;
 148         reset->rcdev.ops = &ccu_reset_ops;
 149         reset->rcdev.owner = dev ? dev->driver->owner : THIS_MODULE;
 150         reset->rcdev.nr_resets = desc->num_resets;
 151         reset->base = reg;
 152         reset->lock = &ccu->lock;
 153         reset->reset_map = desc->resets;
 154
 155         ret = reset_controller_register(&reset->rcdev);
 156         if (ret)
 157                 goto err_del_provider;
 158
 159         return 0;
 160
 161 err_del_provider:
 162         of_clk_del_provider(node);
 163 err_clk_unreg:
 164         while (--i >= 0) {
 165                 struct clk_hw *hw = desc->hw_clks->hws[i];
 166
 167                 if (!hw)
 168                         continue;
 169                 clk_hw_unregister(hw);
 170         }
 171         return ret;
 172 }
 173
 174 static void devm_sunxi_ccu_release(struct device *dev, void *res)
 175 {
 176         struct sunxi_ccu *ccu = res;
 177         const struct sunxi_ccu_desc *desc = ccu->desc;
 178         int i;
 179
 180         reset_controller_unregister(&ccu->reset.rcdev);
 181         of_clk_del_provider(dev->of_node);
 182
 183         for (i = 0; i < desc->hw_clks->num; i++) {
 184                 struct clk_hw *hw = desc->hw_clks->hws[i];
 185
 186                 if (!hw)
 187                         continue;
 188                 clk_hw_unregister(hw);
 189         }
 190 }
 191
 192 int devm_sunxi_ccu_probe(struct device *dev, void __iomem *reg,
 193                          const struct sunxi_ccu_desc *desc)
 194 {
 195         struct sunxi_ccu *ccu;
 196         int ret;
 197
 198         ccu = devres_alloc(devm_sunxi_ccu_release, sizeof(*ccu), GFP_KERNEL);
 199         if (!ccu)
 200                 return -ENOMEM;
 201
 202         ret = sunxi_ccu_probe(ccu, dev, dev->of_node, reg, desc);
 203         if (ret) {
 204                 devres_free(ccu);
 205                 return ret;
 206         }
 207
 208         devres_add(dev, ccu);
 209
 210         return 0;
 211 }
 212 EXPORT_SYMBOL_NS_GPL(devm_sunxi_ccu_probe, SUNXI_CCU);
 213
 214 void of_sunxi_ccu_probe(struct device_node *node, void __iomem *reg,
 215                         const struct sunxi_ccu_desc *desc)
 216 {
 217         struct sunxi_ccu *ccu;
 218         int ret;
 219
 220         ccu = kzalloc(sizeof(*ccu), GFP_KERNEL);
 221         if (!ccu)
 222                 return;
 223
 224         ret = sunxi_ccu_probe(ccu, NULL, node, reg, desc);
 225         if (ret) {
 226                 pr_err("%pOF: probing clocks failed: %d\n", node, ret);
 227                 kfree(ccu);
 228         }
 229 }
 230
 231 MODULE_LICENSE("GPL");