linux/drivers/clk/sunxi-ng/ccu_common.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright 2016 Maxime Ripard
 *
 * Maxime Ripard <[email protected]>
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/device.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/slab.h>

#include "ccu_common.h"
#include "ccu_gate.h"
#include "ccu_reset.h"

struct sunxi_ccu { … };

void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock)
{ … }
EXPORT_SYMBOL_NS_GPL(…);

bool ccu_is_better_rate(struct ccu_common *common,
			unsigned long target_rate,
			unsigned long current_rate,
			unsigned long best_rate)
{ … }
EXPORT_SYMBOL_NS_GPL(…);

/*
 * This clock notifier is called when the frequency of a PLL clock is
 * changed. In common PLL designs, changes to the dividers take effect
 * almost immediately, while changes to the multipliers (implemented
 * as dividers in the feedback loop) take a few cycles to work into
 * the feedback loop for the PLL to stablize.
 *
 * Sometimes when the PLL clock rate is changed, the decrease in the
 * divider is too much for the decrease in the multiplier to catch up.
 * The PLL clock rate will spike, and in some cases, might lock up
 * completely.
 *
 * This notifier callback will gate and then ungate the clock,
 * effectively resetting it, so it proceeds to work. Care must be
 * taken to reparent consumers to other temporary clocks during the
 * rate change, and that this notifier callback must be the first
 * to be registered.
 */
static int ccu_pll_notifier_cb(struct notifier_block *nb,
			       unsigned long event, void *data)
{ … }

int ccu_pll_notifier_register(struct ccu_pll_nb *pll_nb)
{ … }
EXPORT_SYMBOL_NS_GPL(…);

static int sunxi_ccu_probe(struct sunxi_ccu *ccu, struct device *dev,
			   struct device_node *node, void __iomem *reg,
			   const struct sunxi_ccu_desc *desc)
{ … }

static void devm_sunxi_ccu_release(struct device *dev, void *res)
{ … }

int devm_sunxi_ccu_probe(struct device *dev, void __iomem *reg,
			 const struct sunxi_ccu_desc *desc)
{ … }
EXPORT_SYMBOL_NS_GPL(…);

void of_sunxi_ccu_probe(struct device_node *node, void __iomem *reg,
			const struct sunxi_ccu_desc *desc)
{ … }

MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;