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/*
* Copyright 2016 Maxime Ripard
*
* Maxime Ripard <maxime.ripard@free-electrons.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/iopoll.h>
#include <linux/slab.h>
#include "ccu_common.h"
#include "ccu_gate.h"
#include "ccu_reset.h"
static DEFINE_SPINLOCK(ccu_lock);
void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock)
{
void __iomem *addr;
u32 reg;
if (!lock)
return;
if (common->features & CCU_FEATURE_LOCK_REG)
addr = common->base + common->lock_reg;
else
addr = common->base + common->reg;
WARN_ON(readl_relaxed_poll_timeout(addr, reg, reg & lock, 100, 70000));
}
/*
* 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)
{
struct ccu_pll_nb *pll = to_ccu_pll_nb(nb);
int ret = 0;
if (event != POST_RATE_CHANGE)
goto out;
ccu_gate_helper_disable(pll->common, pll->enable);
ret = ccu_gate_helper_enable(pll->common, pll->enable);
if (ret)
goto out;
ccu_helper_wait_for_lock(pll->common, pll->lock);
out:
return notifier_from_errno(ret);
}
int ccu_pll_notifier_register(struct ccu_pll_nb *pll_nb)
{
pll_nb->clk_nb.notifier_call = ccu_pll_notifier_cb;
return clk_notifier_register(pll_nb->common->hw.clk,
&pll_nb->clk_nb);
}
int sunxi_ccu_probe(struct device_node *node, void __iomem *reg,
const struct sunxi_ccu_desc *desc)
{
struct ccu_reset *reset;
int i, ret;
for (i = 0; i < desc->num_ccu_clks; i++) {
struct ccu_common *cclk = desc->ccu_clks[i];
if (!cclk)
continue;
cclk->base = reg;
cclk->lock = &ccu_lock;
}
for (i = 0; i < desc->hw_clks->num ; i++) {
struct clk_hw *hw = desc->hw_clks->hws[i];
if (!hw)
continue;
ret = clk_hw_register(NULL, hw);
if (ret) {
pr_err("Couldn't register clock %s\n",
clk_hw_get_name(hw));
goto err_clk_unreg;
}
}
ret = of_clk_add_hw_provider(node, of_clk_hw_onecell_get,
desc->hw_clks);
if (ret)
goto err_clk_unreg;
reset = kzalloc(sizeof(*reset), GFP_KERNEL);
if (!reset) {
ret = -ENOMEM;
goto err_alloc_reset;
}
reset->rcdev.of_node = node;
reset->rcdev.ops = &ccu_reset_ops;
reset->rcdev.owner = THIS_MODULE;
reset->rcdev.nr_resets = desc->num_resets;
reset->base = reg;
reset->lock = &ccu_lock;
reset->reset_map = desc->resets;
ret = reset_controller_register(&reset->rcdev);
if (ret)
goto err_of_clk_unreg;
return 0;
err_of_clk_unreg:
kfree(reset);
err_alloc_reset:
of_clk_del_provider(node);
err_clk_unreg:
while (--i >= 0) {
struct clk_hw *hw = desc->hw_clks->hws[i];
if (!hw)
continue;
clk_hw_unregister(hw);
}
return ret;
}
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