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linux/drivers/clk/sprd/composite.c

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// SPDX-License-Identifier: GPL-2.0
//
// Spreadtrum composite clock driver
//
// Copyright (C) 2017 Spreadtrum, Inc.
// Author: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
#include <linux/clk-provider.h>
#include "composite.h"
clk: sprd: composite: Switch to determine_rate The Spreadtrum composite clocks implements a mux with a set_parent hook, but doesn't provide a determine_rate implementation. This is a bit odd, since set_parent() is there to, as its name implies, change the parent of a clock. However, the most likely candidate to trigger that parent change is a call to clk_set_rate(), with determine_rate() figuring out which parent is the best suited for a given rate. The other trigger would be a call to clk_set_parent(), but it's far less used, and it doesn't look like there's any obvious user for that clock. So, the set_parent hook is effectively unused, possibly because of an oversight. However, it could also be an explicit decision by the original author to avoid any reparenting but through an explicit call to clk_set_parent(). The driver does implement round_rate() though, which means that we can change the rate of the clock, but we will never get to change the parent. However, It's hard to tell whether it's been done on purpose or not. Since we'll start mandating a determine_rate() implementation, let's convert the round_rate() implementation to a determine_rate(), which will also make the current behavior explicit. And if it was an oversight, the clock behaviour can be adjusted later on. Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Chunyan Zhang <zhang.lyra@gmail.com> Cc: Orson Zhai <orsonzhai@gmail.com> Acked-by: Chunyan Zhang <zhang.lyra@gmail.com> Signed-off-by: Maxime Ripard <maxime@cerno.tech> Link: https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v4-61-971d5077e7d2@cerno.tech Signed-off-by: Stephen Boyd <sboyd@kernel.org>
2023-05-05 04:26:03 -07:00
static int sprd_comp_determine_rate(struct clk_hw *hw,
struct clk_rate_request *req)
{
struct sprd_comp *cc = hw_to_sprd_comp(hw);
return divider_determine_rate(hw, req, NULL, cc->div.width, 0);
}
static unsigned long sprd_comp_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct sprd_comp *cc = hw_to_sprd_comp(hw);
return sprd_div_helper_recalc_rate(&cc->common, &cc->div, parent_rate);
}
static int sprd_comp_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct sprd_comp *cc = hw_to_sprd_comp(hw);
return sprd_div_helper_set_rate(&cc->common, &cc->div,
rate, parent_rate);
}
static u8 sprd_comp_get_parent(struct clk_hw *hw)
{
struct sprd_comp *cc = hw_to_sprd_comp(hw);
return sprd_mux_helper_get_parent(&cc->common, &cc->mux);
}
static int sprd_comp_set_parent(struct clk_hw *hw, u8 index)
{
struct sprd_comp *cc = hw_to_sprd_comp(hw);
return sprd_mux_helper_set_parent(&cc->common, &cc->mux, index);
}
const struct clk_ops sprd_comp_ops = {
.get_parent = sprd_comp_get_parent,
.set_parent = sprd_comp_set_parent,
clk: sprd: composite: Switch to determine_rate The Spreadtrum composite clocks implements a mux with a set_parent hook, but doesn't provide a determine_rate implementation. This is a bit odd, since set_parent() is there to, as its name implies, change the parent of a clock. However, the most likely candidate to trigger that parent change is a call to clk_set_rate(), with determine_rate() figuring out which parent is the best suited for a given rate. The other trigger would be a call to clk_set_parent(), but it's far less used, and it doesn't look like there's any obvious user for that clock. So, the set_parent hook is effectively unused, possibly because of an oversight. However, it could also be an explicit decision by the original author to avoid any reparenting but through an explicit call to clk_set_parent(). The driver does implement round_rate() though, which means that we can change the rate of the clock, but we will never get to change the parent. However, It's hard to tell whether it's been done on purpose or not. Since we'll start mandating a determine_rate() implementation, let's convert the round_rate() implementation to a determine_rate(), which will also make the current behavior explicit. And if it was an oversight, the clock behaviour can be adjusted later on. Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Chunyan Zhang <zhang.lyra@gmail.com> Cc: Orson Zhai <orsonzhai@gmail.com> Acked-by: Chunyan Zhang <zhang.lyra@gmail.com> Signed-off-by: Maxime Ripard <maxime@cerno.tech> Link: https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v4-61-971d5077e7d2@cerno.tech Signed-off-by: Stephen Boyd <sboyd@kernel.org>
2023-05-05 04:26:03 -07:00
.determine_rate = sprd_comp_determine_rate,
.recalc_rate = sprd_comp_recalc_rate,
.set_rate = sprd_comp_set_rate,
};
EXPORT_SYMBOL_GPL(sprd_comp_ops);