Re: [PATCH 10/16] clk: sunxi-ng: Add M-P factor clock support

Maxime Ripard
2016-05-23T17:18:45Z

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Hi,

On Mon, May 23, 2016 at 09:45:16PM +0800, Chen-Yu Tsai wrote:
> Hi,
>
> On Mon, May 9, 2016 at 4:01 AM, Maxime Ripard
> <maxime.ripard@free-electrons.com> wrote:
> > Introduce support for the clocks that combine a linear divider and a
> > power-of-two based one.
>
> A description or formula in the source code (for those of us that forget)
> would be nice. :)

Ack :)

>
> >
> > Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> > ---
> > drivers/clk/sunxi-ng/Makefile | 1 +
> > drivers/clk/sunxi-ng/ccu_mp.c | 158 ++++++++++++++++++++++++++++++++++++++++++
> > drivers/clk/sunxi-ng/ccu_mp.h | 79 +++++++++++++++++++++
> > 3 files changed, 238 insertions(+)
> > create mode 100644 drivers/clk/sunxi-ng/ccu_mp.c
> > create mode 100644 drivers/clk/sunxi-ng/ccu_mp.h
> >
> > diff --git a/drivers/clk/sunxi-ng/Makefile b/drivers/clk/sunxi-ng/Makefile
> > index 063c50f35ad4..09fce7467784 100644
> > --- a/drivers/clk/sunxi-ng/Makefile
> > +++ b/drivers/clk/sunxi-ng/Makefile
> > @@ -5,6 +5,7 @@ obj-y += ccu_div_table.o
> > obj-y += ccu_fixed_factor.o
> > obj-y += ccu_gate.o
> > obj-y += ccu_m.o
> > +obj-y += ccu_mp.o
> > obj-y += ccu_mux.o
> > obj-y += ccu_p.o
> > obj-y += ccu_phase.o
> > diff --git a/drivers/clk/sunxi-ng/ccu_mp.c b/drivers/clk/sunxi-ng/ccu_mp.c
> > new file mode 100644
> > index 000000000000..7181188deba7
> > --- /dev/null
> > +++ b/drivers/clk/sunxi-ng/ccu_mp.c
> > @@ -0,0 +1,158 @@
> > +/*
> > + * Copyright (C) 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.
> > + */
> > +
> > +#include <linux/clk-provider.h>
> > +
> > +#include "ccu_gate.h"
> > +#include "ccu_mp.h"
> > +
> > +static void ccu_mp_find_best(unsigned long parent, unsigned long rate,
> > + unsigned int max_m, unsigned int max_p,
> > + unsigned int *m, unsigned int *p)
> > +{
> > + unsigned long best_rate = 0;
> > + unsigned int best_m = 0, best_p = 0;
> > + unsigned int _m, _p;
> > +
> > + for (_p = 0; _p <= max_p; _p++) {
> > + for (_m = 1; _m <= max_m; _m++) {
> > + unsigned long tmp_rate = (parent >> _p) / _m;
> > +
> > + if (tmp_rate > rate)
> > + continue;
> > +
> > + if ((rate - tmp_rate) < (rate - best_rate)) {
> > + best_rate = tmp_rate;
> > + best_m = _m;
> > + best_p = _p;
> > + }
> > + }
> > + }
> > +
> > + *m = best_m;
> > + *p = best_p;
> > +}
> > +
> > +static unsigned long ccu_mp_round_rate(struct ccu_mux_internal *mux,
> > + unsigned long parent_rate,
> > + unsigned long rate,
> > + void *data)
> > +{
> > + struct ccu_mp *cmp = data;
> > + unsigned int m, p;
> > +
> > + ccu_mp_find_best(parent_rate, rate,
> > + 1 << cmp->m.width, (1 << cmp->p.width) - 1,
> > + &m, &p);
> > +
> > + return (parent_rate >> p) / m;
> > +}
> > +
> > +static void ccu_mp_disable(struct clk_hw *hw)
> > +{
> > + struct ccu_mp *cmp = hw_to_ccu_mp(hw);
> > +
> > + return ccu_gate_helper_disable(&cmp->common, cmp->enable);
> > +}
> > +
> > +static int ccu_mp_enable(struct clk_hw *hw)
> > +{
> > + struct ccu_mp *cmp = hw_to_ccu_mp(hw);
> > +
> > + return ccu_gate_helper_enable(&cmp->common, cmp->enable);
> > +}
> > +
> > +static int ccu_mp_is_enabled(struct clk_hw *hw)
> > +{
> > + struct ccu_mp *cmp = hw_to_ccu_mp(hw);
> > +
> > + return ccu_gate_helper_is_enabled(&cmp->common, cmp->enable);
> > +}
> > +
> > +static unsigned long ccu_mp_recalc_rate(struct clk_hw *hw,
> > + unsigned long parent_rate)
> > +{
> > + struct ccu_mp *cmp = hw_to_ccu_mp(hw);
> > + unsigned int m, p;
> > + u32 reg;
> > +
> > + reg = readl(cmp->common.base + cmp->common.reg);
> > +
> > + m = reg >> cmp->m.shift;
> > + m &= (1 << cmp->m.width) - 1;
> > +
> > + p = reg >> cmp->p.shift;
> > + p &= (1 << cmp->p.width) - 1;
> > +
> > + return (parent_rate >> p) / (m + 1);
> > +}
> > +
> > +static int ccu_mp_determine_rate(struct clk_hw *hw,
> > + struct clk_rate_request *req)
> > +{
> > + struct ccu_mp *cmp = hw_to_ccu_mp(hw);
> > +
> > + return ccu_mux_helper_determine_rate(&cmp->common, &cmp->mux,
> > + req, ccu_mp_round_rate, cmp);
> > +}
> > +
> > +static int ccu_mp_set_rate(struct clk_hw *hw, unsigned long rate,
> > + unsigned long parent_rate)
> > +{
> > + struct ccu_mp *cmp = hw_to_ccu_mp(hw);
> > + unsigned long flags;
> > + unsigned int m, p;
> > + u32 reg;
> > +
> > + ccu_mp_find_best(parent_rate, rate,
> > + 1 << cmp->m.width, (1 << cmp->p.width) - 1,
> > + &m, &p);
> > +
> > +
> > + spin_lock_irqsave(cmp->common.lock, flags);
> > +
> > + reg = readl(cmp->common.base + cmp->common.reg);
> > + reg &= ~GENMASK(cmp->m.width + cmp->m.shift, cmp->m.shift);
> > + reg &= ~GENMASK(cmp->p.width + cmp->p.shift, cmp->p.shift);
>
> width + shift - 1 ? IIRC GENMASK is inclusive at both ends.

Indeed, will fix.

>
> > +
> > + writel(reg | (p << cmp->p.shift) | ((m - 1) << cmp->m.shift),
> > + cmp->common.base + cmp->common.reg);
> > +
> > + spin_unlock_irqrestore(cmp->common.lock, flags);
> > +
> > + return 0;
> > +}
> > +
> > +static u8 ccu_mp_get_parent(struct clk_hw *hw)
> > +{
> > + struct ccu_mp *cmp = hw_to_ccu_mp(hw);
> > +
> > + return ccu_mux_helper_get_parent(&cmp->common, &cmp->mux);
> > +}
> > +
> > +static int ccu_mp_set_parent(struct clk_hw *hw, u8 index)
> > +{
> > + struct ccu_mp *cmp = hw_to_ccu_mp(hw);
> > +
> > + return ccu_mux_helper_set_parent(&cmp->common, &cmp->mux, index);
> > +}
> > +
> > +const struct clk_ops ccu_mp_ops = {
> > + .disable = ccu_mp_disable,
> > + .enable = ccu_mp_enable,
> > + .is_enabled = ccu_mp_is_enabled,
> > +
> > + .get_parent = ccu_mp_get_parent,
> > + .set_parent = ccu_mp_set_parent,
> > +
> > + .determine_rate = ccu_mp_determine_rate,
> > + .recalc_rate = ccu_mp_recalc_rate,
> > + .set_rate = ccu_mp_set_rate,
> > +};
> > diff --git a/drivers/clk/sunxi-ng/ccu_mp.h b/drivers/clk/sunxi-ng/ccu_mp.h
> > new file mode 100644
> > index 000000000000..95da9c46cd4f
> > --- /dev/null
> > +++ b/drivers/clk/sunxi-ng/ccu_mp.h
> > @@ -0,0 +1,79 @@
> > +/*
> > + * Copyright (c) 2016 Maxime Ripard. All rights reserved.
> > + *
> > + * This software is licensed under the terms of the GNU General Public
> > + * License version 2, as published by the Free Software Foundation, and
> > + * may be copied, distributed, and modified under those terms.
> > + *
> > + * 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.
> > + */
> > +
> > +#ifndef _CCU_MP_H_
> > +#define _CCU_MP_H_
> > +
> > +#include <linux/clk-provider.h>
> > +
> > +#include "ccu_common.h"
> > +#include "ccu_factor.h"
> > +#include "ccu_mux.h"
> > +
> > +struct ccu_mp {
> > + u32 enable;
> > +
> > + struct ccu_factor m;
> > + struct ccu_factor p;
> > + struct ccu_mux_internal mux;
> > + struct ccu_common common;
> > +};
> > +
> > +#define SUNXI_CCU_MP_WITH_MUX(_struct, _name, _parents, _reg, \
> > + _mshift, _mwidth, \
> > + _pshift, _pwidth, \
> > + _muxshift, _muxwidth, \
> > + _flags) \
> > + struct ccu_mp _struct = { \
> > + .m = SUNXI_CLK_FACTOR(_mshift, _mwidth), \
> > + .p = SUNXI_CLK_FACTOR(_pshift, _pwidth), \
> > + .mux = SUNXI_CLK_MUX(_muxshift, _muxwidth), \
> > + .common = { \
> > + .reg = _reg, \
> > + .hw.init = SUNXI_HW_INIT_PARENTS(_name, \
> > + _parents, \
> > + &ccu_mp_ops, \
> > + _flags), \
> > + } \
> > + }
>
> Use the latter to simplify this one?
>
> > +
> > +#define SUNXI_CCU_MP_WITH_MUX_GATE(_struct, _name, _parents, _reg, \
>
> We could merge _struct with _name ...
>
> > + _mshift, _mwidth, \
> > + _pshift, _pwidth, \
> > + _muxshift, _muxwidth, \
> > + _gate, _flags) \
> > + struct ccu_mp _struct = { \
>
> and have struct ccu_mp _name##_clk = {

Unfortunately, that prevents to use dashes as clock names, which is
something we've done in the past. Having a separate name allows us to
use whatever we want.

Maxime

---
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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