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Message-ID: <50651277-d8db-0a38-3ca8-c991480c1e6a@gmail.com>
Date: Thu, 31 Oct 2019 20:07:44 +0300
From: Dmitry Osipenko <digetx@...il.com>
To: Peter De Schrijver <pdeschrijver@...dia.com>
Cc: Thierry Reding <thierry.reding@...il.com>,
Jonathan Hunter <jonathanh@...dia.com>,
Prashant Gaikwad <pgaikwad@...dia.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Viresh Kumar <viresh.kumar@...aro.org>,
Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>,
Peter Geis <pgwipeout@...il.com>,
Nicolas Chauvet <kwizart@...il.com>,
Marcel Ziswiler <marcel.ziswiler@...adex.com>,
linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 01/10] clk: tegra: Add custom CCLK implementation
31.10.2019 00:33, Dmitry Osipenko пишет:
> CCLK stands for "CPU Clock", CPU core is running off CCLK. CCLK supports
> multiple parents, it has internal clock divider and a clock skipper.
> PLLX is the main CCLK parent that provides clock rates above 1GHz and it
> has special property such that the CCLK's internal divider is set into
> bypass mode when PLLX is selected as a parent for CCLK.
>
> This patch forks generic Super Clock into CCLK implementation which takes
> into account all CCLK specifics. The proper CCLK implementation is needed
> by the upcoming Tegra20 CPUFreq driver update that will allow to utilize
> the generic cpufreq-dt driver by moving intermediate clock selection into
> the clock driver.
>
> Note that technically this patch could be squashed into clk-super.c, but
> it is cleaner to have a separate source file. Also note that currently all
> CCLKLP bits are left in the clk-super.c and only CCLKG is supported by
> clk-tegra-super-cclk. It shouldn't be difficult to move the CCLKLP bits,
> but CCLKLP is not used by anything in kernel and thus better not to touch
> it for now.
>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
> drivers/clk/tegra/Makefile | 1 +
> drivers/clk/tegra/clk-tegra-super-cclk.c | 176 +++++++++++++++++++++++
> drivers/clk/tegra/clk.h | 11 +-
> 3 files changed, 186 insertions(+), 2 deletions(-)
> create mode 100644 drivers/clk/tegra/clk-tegra-super-cclk.c
>
> diff --git a/drivers/clk/tegra/Makefile b/drivers/clk/tegra/Makefile
> index df966ca06788..f04b490f5416 100644
> --- a/drivers/clk/tegra/Makefile
> +++ b/drivers/clk/tegra/Makefile
> @@ -14,6 +14,7 @@ obj-y += clk-tegra-audio.o
> obj-y += clk-tegra-periph.o
> obj-y += clk-tegra-pmc.o
> obj-y += clk-tegra-fixed.o
> +obj-y += clk-tegra-super-cclk.o
> obj-y += clk-tegra-super-gen4.o
> obj-$(CONFIG_TEGRA_CLK_EMC) += clk-emc.o
> obj-$(CONFIG_ARCH_TEGRA_2x_SOC) += clk-tegra20.o
> diff --git a/drivers/clk/tegra/clk-tegra-super-cclk.c b/drivers/clk/tegra/clk-tegra-super-cclk.c
> new file mode 100644
> index 000000000000..5cff8363c978
> --- /dev/null
> +++ b/drivers/clk/tegra/clk-tegra-super-cclk.c
> @@ -0,0 +1,176 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Based on clk-super.c
> + * Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
> + *
> + * Based on older tegra20-cpufreq driver by Colin Cross <ccross@...gle.com>
> + * Copyright (C) 2010 Google, Inc.
> + *
> + * Author: Dmitry Osipenko <digetx@...il.com>
> + * Copyright (C) 2019 GRATE-DRIVER project
> + */
> +
> +#include <linux/bits.h>
> +#include <linux/clk-provider.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +
> +#include "clk.h"
> +
> +#define PLLP_INDEX 4
> +#define PLLX_INDEX 8
> +
> +#define SUPER_CDIV_ENB BIT(31)
> +
> +static u8 cclk_super_get_parent(struct clk_hw *hw)
> +{
> + return tegra_clk_super_ops.get_parent(hw);
> +}
> +
> +static int cclk_super_set_parent(struct clk_hw *hw, u8 index)
> +{
> + return tegra_clk_super_ops.set_parent(hw, index);
> +}
> +
> +static int cclk_super_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + return tegra_clk_super_ops.set_rate(hw, rate, parent_rate);
> +}
> +
> +static unsigned long cclk_super_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + if (cclk_super_get_parent(hw) == PLLX_INDEX)
> + return parent_rate;
> +
> + return tegra_clk_super_ops.recalc_rate(hw, parent_rate);
> +}
> +
> +static int cclk_super_determine_rate(struct clk_hw *hw,
> + struct clk_rate_request *req)
> +{
> + struct clk_hw *pllp_hw = clk_hw_get_parent_by_index(hw, PLLP_INDEX);
> + struct clk_hw *pllx_hw = clk_hw_get_parent_by_index(hw, PLLX_INDEX);
> + struct tegra_clk_super_mux *super = to_clk_super_mux(hw);
> + unsigned long pllp_rate;
> + long rate = req->rate;
> +
> + if (WARN_ON_ONCE(!pllp_hw || !pllx_hw))
> + return -EINVAL;
> +
> + /*
> + * Switch parent to PLLP for all CCLK rates that are suitable for PLLP.
> + * PLLX will be disabled in this case, saving some power.
> + */
> + pllp_rate = clk_hw_get_rate(pllp_hw);
> +
> + if (rate <= pllp_rate) {
> + if (super->flags & TEGRA20_SUPER_CLK)
> + rate = pllp_rate;
> + else
> + rate = tegra_clk_super_ops.round_rate(hw, rate,
> + &pllp_rate);
> +
> + req->best_parent_rate = pllp_rate;
> + req->best_parent_hw = pllp_hw;
> + req->rate = rate;
> + } else {
> + rate = clk_hw_round_rate(pllx_hw, rate);
> + req->best_parent_rate = rate;
> + req->best_parent_hw = pllx_hw;
> + req->rate = rate;
> + }
> +
> + if (WARN_ON_ONCE(rate <= 0))
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static const struct clk_ops tegra_cclk_super_ops = {
> + .get_parent = cclk_super_get_parent,
> + .set_parent = cclk_super_set_parent,
> + .set_rate = cclk_super_set_rate,
> + .recalc_rate = cclk_super_recalc_rate,
> + .determine_rate = cclk_super_determine_rate,
> +};
> +
> +static const struct clk_ops tegra_cclk_super_mux_ops = {
> + .get_parent = cclk_super_get_parent,
> + .set_parent = cclk_super_set_parent,
> + .determine_rate = cclk_super_determine_rate,
> +};
> +
> +struct clk *tegra_clk_register_super_cclk(const char *name,
> + const char * const *parent_names, u8 num_parents,
> + unsigned long flags, void __iomem *reg, u8 clk_super_flags,
> + spinlock_t *lock)
> +{
> + struct tegra_clk_super_mux *super;
> + struct clk *clk;
> + struct clk_init_data init;
> + u32 val;
> +
> + super = kzalloc(sizeof(*super), GFP_KERNEL);
> + if (!super)
> + return ERR_PTR(-ENOMEM);
> +
> + init.name = name;
> + init.flags = flags;
> + init.parent_names = parent_names;
> + init.num_parents = num_parents;
> +
> + super->reg = reg;
> + super->lock = lock;
> + super->width = 4;
> + super->flags = clk_super_flags;
> + super->hw.init = &init;
> +
> + if (super->flags & TEGRA20_SUPER_CLK) {
> + init.ops = &tegra_cclk_super_mux_ops;
> + } else {
> + init.ops = &tegra_cclk_super_ops;
> +
> + super->frac_div.reg = reg + 4;
> + super->frac_div.shift = 16;
> + super->frac_div.width = 8;
> + super->frac_div.frac_width = 1;
> + super->frac_div.lock = lock;
> + super->div_ops = &tegra_clk_frac_div_ops;
> + }
> +
> + /*
> + * Tegra30+ has the following CPUG clock topology:
> + *
> + * OVERHEAT+----+
> + * +---+ +-------+ +---+ |
> + * PLLP+->+ +->+DIVIDER+->+0 | v
> + * | | +-------+ | | +-------+ +-+-+
> + * PLLC+->+MUX| |OUT+->+SKIPPER+-+------------>+0 |
> + * ... | | | | +-------+ | | |
> + * PLLX+->+-->+------------>+1 | | |OUT|->+CPU
> + * +---+ +-+-+ | +-------+ | |
> + * ^ +->+ DIV2 +->+1 |
> + * | |SKIPPER| +---+
> + * PLLX_SEL+---+ +-------+
Probably this will be a bit better:
+---+ +-------+ +-+ +-+ +-+
PLLP+->+ +->+DIVIDER+->+0| +-------->+0| ------------->+0|
| | +-------+ | | | +---+ | | | | |
PLLC+->+MUX| | +->+ | S | | +->+ | +>
... | | | | | | K | | | | +-------+ | |
PLLX+->+-->+------------>+1| +->+ I +->+1| +->+ DIV2 +->+1|
+---+ +++ | P | +++ |SKIPPER| +++
^ | P | ^ +-------+ ^
| | E | | |
PLLX_SEL+--+ | R | | OVERHEAT+--+
+---+ |
|
SUPER_CDIV_ENB+--+
[snip]
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