Re: [PATCH V2] clk: Add composite clock type

[Tomasz Figa]

Hi Prashant,

Thank you for your patch. Please see some comments inline.

On Monday 04 of February 2013 13:41:22 Prashant Gaikwad wrote:
> Not all clocks are required to be decomposed into basic clock
> types but at the same time want to use the functionality
> provided by these basic clock types instead of duplicating.
> 
> For example, Tegra SoC has ~100 clocks which can be decomposed
> into Mux -> Div -> Gate clock types making the clock count to
> ~300. Also, parent change operation can not be performed on gate
> clock which forces to use mux clock in driver if want to change
> the parent.
> 
> Instead aggregate the basic clock types functionality into one
> clock and just use this clock for all operations. This clock
> type re-uses the functionality of basic clock types and not
> limited to basic clock types but any hardware-specific
> implementation.
> 
> Signed-off-by: Prashant Gaikwad <pgaikwad@xxxxxxxxxx>
> ---
> 
> Changes from V1:
> - 2nd patch dropped as the concept is acked by Mike.
> - Fixed comments from Stephen.
> 
> ---
>  drivers/clk/Makefile         |    1 +
>  drivers/clk/clk-composite.c  |  208
> ++++++++++++++++++++++++++++++++++++++++++ include/linux/clk-provider.h
> |   30 ++++++
>  3 files changed, 239 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/clk/clk-composite.c
> 
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index ce77077..2287848 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -7,6 +7,7 @@ obj-$(CONFIG_COMMON_CLK)	+= clk-fixed-factor.o
>  obj-$(CONFIG_COMMON_CLK)	+= clk-fixed-rate.o
>  obj-$(CONFIG_COMMON_CLK)	+= clk-gate.o
>  obj-$(CONFIG_COMMON_CLK)	+= clk-mux.o
> +obj-$(CONFIG_COMMON_CLK)	+= clk-composite.o
> 
>  # SoCs specific
>  obj-$(CONFIG_ARCH_BCM2835)	+= clk-bcm2835.o
> diff --git a/drivers/clk/clk-composite.c b/drivers/clk/clk-composite.c
> new file mode 100644
> index 0000000..5a6587f
> --- /dev/null
> +++ b/drivers/clk/clk-composite.c
> @@ -0,0 +1,208 @@
> +/*
> + * Copyright (c) 2013 NVIDIA CORPORATION.  All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify
> it + * under the terms and conditions of the GNU General Public
> License, + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see
> <http://www.gnu.org/licenses/>. + */
> +
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/err.h>
> +#include <linux/slab.h>
> +
> +#define to_clk_composite(_hw) container_of(_hw, struct clk_composite,
> hw) +
> +static u8 clk_composite_get_parent(struct clk_hw *hw)
> +{
> +	struct clk_composite *composite = to_clk_composite(hw);
> +	const struct clk_ops *mux_ops = composite->mux_ops;
> +	struct clk_hw *mux_hw = composite->mux_hw;
> +
> +	mux_hw->clk = hw->clk;

Why is this needed? Looks like this filed is already being initialized in 
clk_register_composite.

> +
> +	return mux_ops->get_parent(mux_hw);
> +}
> +
> +static int clk_composite_set_parent(struct clk_hw *hw, u8 index)
> +{
> +	struct clk_composite *composite = to_clk_composite(hw);
> +	const struct clk_ops *mux_ops = composite->mux_ops;
> +	struct clk_hw *mux_hw = composite->mux_hw;
> +
> +	mux_hw->clk = hw->clk;

Ditto.

> +
> +	return mux_ops->set_parent(mux_hw, index);
> +}
> +
> +static unsigned long clk_composite_recalc_rate(struct clk_hw *hw,
> +					    unsigned long parent_rate)
> +{
> +	struct clk_composite *composite = to_clk_composite(hw);
> +	const struct clk_ops *div_ops = composite->div_ops;
> +	struct clk_hw *div_hw = composite->div_hw;
> +
> +	div_hw->clk = hw->clk;

Ditto.

> +
> +	return div_ops->recalc_rate(div_hw, parent_rate);
> +}
> +
> +static long clk_composite_round_rate(struct clk_hw *hw, unsigned long
> rate, +				  unsigned long *prate)
> +{
> +	struct clk_composite *composite = to_clk_composite(hw);
> +	const struct clk_ops *div_ops = composite->div_ops;
> +	struct clk_hw *div_hw = composite->div_hw;
> +
> +	div_hw->clk = hw->clk;

Ditto.

> +
> +	return div_ops->round_rate(div_hw, rate, prate);
> +}
> +
> +static int clk_composite_set_rate(struct clk_hw *hw, unsigned long
> rate, +			       unsigned long parent_rate)
> +{
> +	struct clk_composite *composite = to_clk_composite(hw);
> +	const struct clk_ops *div_ops = composite->div_ops;
> +	struct clk_hw *div_hw = composite->div_hw;
> +
> +	div_hw->clk = hw->clk;

Ditto.

> +
> +	return div_ops->set_rate(div_hw, rate, parent_rate);
> +}
> +
> +static int clk_composite_is_enabled(struct clk_hw *hw)
> +{
> +	struct clk_composite *composite = to_clk_composite(hw);
> +	const struct clk_ops *gate_ops = composite->gate_ops;
> +	struct clk_hw *gate_hw = composite->gate_hw;
> +
> +	gate_hw->clk = hw->clk;

Ditto.

> +
> +	return gate_ops->is_enabled(gate_hw);
> +}
> +
> +static int clk_composite_enable(struct clk_hw *hw)
> +{
> +	struct clk_composite *composite = to_clk_composite(hw);
> +	const struct clk_ops *gate_ops = composite->gate_ops;
> +	struct clk_hw *gate_hw = composite->gate_hw;
> +
> +	gate_hw->clk = hw->clk;

Ditto.

> +
> +	return gate_ops->enable(gate_hw);
> +}
> +
> +static void clk_composite_disable(struct clk_hw *hw)
> +{
> +	struct clk_composite *composite = to_clk_composite(hw);
> +	const struct clk_ops *gate_ops = composite->gate_ops;
> +	struct clk_hw *gate_hw = composite->gate_hw;
> +
> +	gate_hw->clk = hw->clk;

Ditto.

> +
> +	gate_ops->disable(gate_hw);
> +}
> +
> +struct clk *clk_register_composite(struct device *dev, const char
> *name, +			const char **parent_names, int num_parents,
> +			struct clk_hw *mux_hw, const struct clk_ops *mux_ops,
> +			struct clk_hw *div_hw, const struct clk_ops *div_ops,
> +			struct clk_hw *gate_hw, const struct clk_ops *gate_ops,
> +			unsigned long flags)
> +{
> +	struct clk *clk;
> +	struct clk_init_data init;
> +	struct clk_composite *composite;
> +	struct clk_ops *clk_composite_ops;
> +
> +	composite = kzalloc(sizeof(*composite), GFP_KERNEL);
> +	if (!composite) {
> +		pr_err("%s: could not allocate composite clk\n", __func__);
> +		return ERR_PTR(-ENOMEM);
> +	}
> +
> +	init.name = name;
> +	init.flags = flags | CLK_IS_BASIC;
> +	init.parent_names = parent_names;
> +	init.num_parents = num_parents;
> +
> +	/* allocate the clock ops */
> +	clk_composite_ops = kzalloc(sizeof(*clk_composite_ops), GFP_KERNEL);
> +	if (!clk_composite_ops) {
> +		pr_err("%s: could not allocate clk ops\n", __func__);
> +		kfree(composite);
> +		return ERR_PTR(-ENOMEM);
> +	}

Maybe it would be better to embed this struct clk_ops inside struct 
clk_composite? This would allow to get rid of this allocation.

> +
> +	if (mux_hw && mux_ops) {
> +		if (!mux_ops->get_parent || !mux_ops->set_parent) {
> +			clk = ERR_PTR(-EINVAL);
> +			goto err;
> +		}
> +
> +		composite->mux_hw = mux_hw;
> +		composite->mux_ops = mux_ops;
> +		clk_composite_ops->get_parent = clk_composite_get_parent;
> +		clk_composite_ops->set_parent = clk_composite_set_parent;
> +	}
> +
> +	if (div_hw && div_ops) {
> +		if (!div_ops->recalc_rate || !div_ops->round_rate ||
> +		    !div_ops->set_rate) {
> +			clk = ERR_PTR(-EINVAL);
> +			goto err;
> +		}
> +
> +		composite->div_hw = div_hw;
> +		composite->div_ops = div_ops;
> +		clk_composite_ops->recalc_rate = clk_composite_recalc_rate;
> +		clk_composite_ops->round_rate = clk_composite_round_rate;
> +		clk_composite_ops->set_rate = clk_composite_set_rate;
> +	}
> +
> +	if (gate_hw && gate_ops) {
> +		if (!gate_ops->is_enabled || !gate_ops->enable ||
> +		    !gate_ops->disable) {
> +			clk = ERR_PTR(-EINVAL);
> +			goto err;
> +		}
> +
> +		composite->gate_hw = gate_hw;
> +		composite->gate_ops = gate_ops;
> +		clk_composite_ops->is_enabled = clk_composite_is_enabled;
> +		clk_composite_ops->enable = clk_composite_enable;
> +		clk_composite_ops->disable = clk_composite_disable;
> +	}
> +
> +	init.ops = clk_composite_ops;
> +	composite->hw.init = &init;
> +
> +	clk = clk_register(dev, &composite->hw);
> +	if (IS_ERR(clk))
> +		goto err;
> +
> +	if (composite->mux_hw)
> +		composite->mux_hw->clk = clk;
> +
> +	if (composite->div_hw)
> +		composite->div_hw->clk = clk;
> +
> +	if (composite->gate_hw)
> +		composite->gate_hw->clk = clk;
> +
> +	return clk;
> +
> +err:
> +	kfree(clk_composite_ops);
> +	kfree(composite);
> +	return clk;
> +}
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 7f197d7..f1a36aa 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -325,6 +325,36 @@ struct clk *clk_register_fixed_factor(struct device
> *dev, const char *name, const char *parent_name, unsigned long flags,
>  		unsigned int mult, unsigned int div);
> 
> +/***
> + * struct clk_composite - aggregate clock of mux, divider and gate
> clocks + *
> + * @hw:		handle between common and hardware-specific interfaces
> + * @mux_hw:	handle between composite and hardware-specifix mux clock
> + * @div_hw:	handle between composite and hardware-specifix divider
> clock + * @gate_hw:	handle between composite and hardware-specifix gate
> clock + * @mux_ops:	clock ops for mux
> + * @div_ops:	clock ops for divider
> + * @gate_ops:	clock ops for gate
> + */
> +struct clk_composite {
> +	struct clk_hw	hw;

As I suggested above:

	struct clk_ops	ops;

> +
> +	struct clk_hw	*mux_hw;
> +	struct clk_hw	*div_hw;
> +	struct clk_hw	*gate_hw;
> +
> +	const struct clk_ops	*mux_ops;
> +	const struct clk_ops	*div_ops;
> +	const struct clk_ops	*gate_ops;
> +};
> +
> +struct clk *clk_register_composite(struct device *dev, const char
> *name, +		const char **parent_names, int num_parents,
> +		struct clk_hw *mux_hw, const struct clk_ops *mux_ops,
> +		struct clk_hw *div_hw, const struct clk_ops *div_ops,
> +		struct clk_hw *gate_hw, const struct clk_ops *gate_ops,
> +		unsigned long flags);
> +
>  /**
>   * clk_register - allocate a new clock, register it and return an
> opaque cookie * @dev: device that is registering this clock

Best regards,
-- 
Tomasz Figa
Samsung Poland R&D Center
SW Solution Development, Linux Platform

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