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/slab.h>
  13
  14 #include "ccu_common.h"
  15 #include "ccu_gate.h"
  16 #include "ccu_reset.h"
  17
  18 struct sunxi_ccu {
  19         const struct sunxi_ccu_desc     *desc;
  20         struct ccu_reset                reset;
  21 };
  22
  23 static DEFINE_SPINLOCK(ccu_lock);
  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
  41 /*
  42  * This clock notifier is called when the frequency of a PLL clock is
  43  * changed. In common PLL designs, changes to the dividers take effect
  44  * almost immediately, while changes to the multipliers (implemented
  45  * as dividers in the feedback loop) take a few cycles to work into
  46  * the feedback loop for the PLL to stablize.
  47  *
  48  * Sometimes when the PLL clock rate is changed, the decrease in the
  49  * divider is too much for the decrease in the multiplier to catch up.
  50  * The PLL clock rate will spike, and in some cases, might lock up
  51  * completely.
  52  *
  53  * This notifier callback will gate and then ungate the clock,
  54  * effectively resetting it, so it proceeds to work. Care must be
  55  * taken to reparent consumers to other temporary clocks during the
  56  * rate change, and that this notifier callback must be the first
  57  * to be registered.
  58  */
  59 static int ccu_pll_notifier_cb(struct notifier_block *nb,
  60                                unsigned long event, void *data)
  61 {
  62         struct ccu_pll_nb *pll = to_ccu_pll_nb(nb);
  63         int ret = 0;
  64
  65         if (event != POST_RATE_CHANGE)
  66                 goto out;
  67
  68         ccu_gate_helper_disable(pll->common, pll->enable);
  69
  70         ret = ccu_gate_helper_enable(pll->common, pll->enable);
  71         if (ret)
  72                 goto out;
  73
  74         ccu_helper_wait_for_lock(pll->common, pll->lock);
  75
  76 out:
  77         return notifier_from_errno(ret);
  78 }
  79
  80 int ccu_pll_notifier_register(struct ccu_pll_nb *pll_nb)
  81 {
  82         pll_nb->clk_nb.notifier_call = ccu_pll_notifier_cb;
  83
  84         return clk_notifier_register(pll_nb->common->hw.clk,
  85                                      &pll_nb->clk_nb);
  86 }
  87
  88 static int sunxi_ccu_probe(struct sunxi_ccu *ccu, struct device *dev,
  89                            struct device_node *node, void __iomem *reg,
  90                            const struct sunxi_ccu_desc *desc)
  91 {
  92         struct ccu_reset *reset;
  93         int i, ret;
  94
  95         ccu->desc = desc;
  96
  97         for (i = 0; i < desc->num_ccu_clks; i++) {
  98                 struct ccu_common *cclk = desc->ccu_clks[i];
  99
 100                 if (!cclk)
 101                         continue;
 102
 103                 cclk->base = reg;
 104                 cclk->lock = &ccu_lock;
 105         }
 106
 107         for (i = 0; i < desc->hw_clks->num ; i++) {
 108                 struct clk_hw *hw = desc->hw_clks->hws[i];
 109                 const char *name;
 110
 111                 if (!hw)
 112                         continue;
 113
 114                 name = hw->init->name;
 115                 if (dev)
 116                         ret = clk_hw_register(dev, hw);
 117                 else
 118                         ret = of_clk_hw_register(node, hw);
 119                 if (ret) {
 120                         pr_err("Couldn't register clock %d - %s\n", i, name);
 121                         goto err_clk_unreg;
 122                 }
 123         }
 124
 125         ret = of_clk_add_hw_provider(node, of_clk_hw_onecell_get,
 126                                      desc->hw_clks);
 127         if (ret)
 128                 goto err_clk_unreg;
 129
 130         reset = &ccu->reset;
 131         reset->rcdev.of_node = node;
 132         reset->rcdev.ops = &ccu_reset_ops;
 133         reset->rcdev.owner = dev ? dev->driver->owner : THIS_MODULE;
 134         reset->rcdev.nr_resets = desc->num_resets;
 135         reset->base = reg;
 136         reset->lock = &ccu_lock;
 137         reset->reset_map = desc->resets;
 138
 139         ret = reset_controller_register(&reset->rcdev);
 140         if (ret)
 141                 goto err_del_provider;
 142
 143         return 0;
 144
 145 err_del_provider:
 146         of_clk_del_provider(node);
 147 err_clk_unreg:
 148         while (--i >= 0) {
 149                 struct clk_hw *hw = desc->hw_clks->hws[i];
 150
 151                 if (!hw)
 152                         continue;
 153                 clk_hw_unregister(hw);
 154         }
 155         return ret;
 156 }
 157
 158 static void devm_sunxi_ccu_release(struct device *dev, void *res)
 159 {
 160         struct sunxi_ccu *ccu = res;
 161         const struct sunxi_ccu_desc *desc = ccu->desc;
 162         int i;
 163
 164         reset_controller_unregister(&ccu->reset.rcdev);
 165         of_clk_del_provider(dev->of_node);
 166
 167         for (i = 0; i < desc->hw_clks->num; i++) {
 168                 struct clk_hw *hw = desc->hw_clks->hws[i];
 169
 170                 if (!hw)
 171                         continue;
 172                 clk_hw_unregister(hw);
 173         }
 174 }
 175
 176 int devm_sunxi_ccu_probe(struct device *dev, void __iomem *reg,
 177                          const struct sunxi_ccu_desc *desc)
 178 {
 179         struct sunxi_ccu *ccu;
 180         int ret;
 181
 182         ccu = devres_alloc(devm_sunxi_ccu_release, sizeof(*ccu), GFP_KERNEL);
 183         if (!ccu)
 184                 return -ENOMEM;
 185
 186         ret = sunxi_ccu_probe(ccu, dev, dev->of_node, reg, desc);
 187         if (ret) {
 188                 devres_free(ccu);
 189                 return ret;
 190         }
 191
 192         devres_add(dev, ccu);
 193
 194         return 0;
 195 }
 196
 197 void of_sunxi_ccu_probe(struct device_node *node, void __iomem *reg,
 198                         const struct sunxi_ccu_desc *desc)
 199 {
 200         struct sunxi_ccu *ccu;
 201         int ret;
 202
 203         ccu = kzalloc(sizeof(*ccu), GFP_KERNEL);
 204         if (!ccu)
 205                 return;
 206
 207         ret = sunxi_ccu_probe(ccu, NULL, node, reg, desc);
 208         if (ret) {
 209                 pr_err("%pOF: probing clocks failed: %d\n", node, ret);
 210                 kfree(ccu);
 211         }
 212 }