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/iopoll.h>
 11#include <linux/slab.h>
 12
 13#include "ccu_common.h"
 14#include "ccu_gate.h"
 15#include "ccu_reset.h"
 16
 17static DEFINE_SPINLOCK(ccu_lock);
 18
 19void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock)
 20{
 21	void __iomem *addr;
 22	u32 reg;
 23
 24	if (!lock)
 25		return;
 26
 27	if (common->features & CCU_FEATURE_LOCK_REG)
 28		addr = common->base + common->lock_reg;
 29	else
 30		addr = common->base + common->reg;
 31
 32	WARN_ON(readl_relaxed_poll_timeout(addr, reg, reg & lock, 100, 70000));
 33}
 34
 35/*
 36 * This clock notifier is called when the frequency of a PLL clock is
 37 * changed. In common PLL designs, changes to the dividers take effect
 38 * almost immediately, while changes to the multipliers (implemented
 39 * as dividers in the feedback loop) take a few cycles to work into
 40 * the feedback loop for the PLL to stablize.
 41 *
 42 * Sometimes when the PLL clock rate is changed, the decrease in the
 43 * divider is too much for the decrease in the multiplier to catch up.
 44 * The PLL clock rate will spike, and in some cases, might lock up
 45 * completely.
 46 *
 47 * This notifier callback will gate and then ungate the clock,
 48 * effectively resetting it, so it proceeds to work. Care must be
 49 * taken to reparent consumers to other temporary clocks during the
 50 * rate change, and that this notifier callback must be the first
 51 * to be registered.
 52 */
 53static int ccu_pll_notifier_cb(struct notifier_block *nb,
 54			       unsigned long event, void *data)
 55{
 56	struct ccu_pll_nb *pll = to_ccu_pll_nb(nb);
 57	int ret = 0;
 58
 59	if (event != POST_RATE_CHANGE)
 60		goto out;
 61
 62	ccu_gate_helper_disable(pll->common, pll->enable);
 63
 64	ret = ccu_gate_helper_enable(pll->common, pll->enable);
 65	if (ret)
 66		goto out;
 67
 68	ccu_helper_wait_for_lock(pll->common, pll->lock);
 69
 70out:
 71	return notifier_from_errno(ret);
 72}
 73
 74int ccu_pll_notifier_register(struct ccu_pll_nb *pll_nb)
 75{
 76	pll_nb->clk_nb.notifier_call = ccu_pll_notifier_cb;
 77
 78	return clk_notifier_register(pll_nb->common->hw.clk,
 79				     &pll_nb->clk_nb);
 80}
 81
 82int sunxi_ccu_probe(struct device_node *node, void __iomem *reg,
 83		    const struct sunxi_ccu_desc *desc)
 84{
 85	struct ccu_reset *reset;
 86	int i, ret;
 87
 88	for (i = 0; i < desc->num_ccu_clks; i++) {
 89		struct ccu_common *cclk = desc->ccu_clks[i];
 90
 91		if (!cclk)
 92			continue;
 93
 94		cclk->base = reg;
 95		cclk->lock = &ccu_lock;
 96	}
 97
 98	for (i = 0; i < desc->hw_clks->num ; i++) {
 99		struct clk_hw *hw = desc->hw_clks->hws[i];
100		const char *name;
101
102		if (!hw)
103			continue;
104
105		name = hw->init->name;
106		ret = of_clk_hw_register(node, hw);
107		if (ret) {
108			pr_err("Couldn't register clock %d - %s\n", i, name);
109			goto err_clk_unreg;
110		}
111	}
112
113	ret = of_clk_add_hw_provider(node, of_clk_hw_onecell_get,
114				     desc->hw_clks);
115	if (ret)
116		goto err_clk_unreg;
117
118	reset = kzalloc(sizeof(*reset), GFP_KERNEL);
119	if (!reset) {
120		ret = -ENOMEM;
121		goto err_alloc_reset;
122	}
123
124	reset->rcdev.of_node = node;
125	reset->rcdev.ops = &ccu_reset_ops;
126	reset->rcdev.owner = THIS_MODULE;
127	reset->rcdev.nr_resets = desc->num_resets;
128	reset->base = reg;
129	reset->lock = &ccu_lock;
130	reset->reset_map = desc->resets;
131
132	ret = reset_controller_register(&reset->rcdev);
133	if (ret)
134		goto err_of_clk_unreg;
135
136	return 0;
137
138err_of_clk_unreg:
139	kfree(reset);
140err_alloc_reset:
141	of_clk_del_provider(node);
142err_clk_unreg:
143	while (--i >= 0) {
144		struct clk_hw *hw = desc->hw_clks->hws[i];
145
146		if (!hw)
147			continue;
148		clk_hw_unregister(hw);
149	}
150	return ret;
151}