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