Date:	Wed, 12 Oct 2011 14:46:47 +0800
From:	Richard Zhao <richard.zhao@...escale.com>
To:	Mike Turquette <mturquette@...com>
CC:	<linux-kernel@...r.kernel.org>, <paul@...an.com>,
	<linaro-dev@...ts.linaro.org>, <linus.walleij@...ricsson.com>,
	<patches@...aro.org>, <eric.miao@...aro.org>,
	<broonie@...nsource.wolfsonmicro.com>, <magnus.damm@...il.com>,
	<amit.kucheria@...aro.org>, <richard.zhao@...aro.org>,
	<grant.likely@...retlab.ca>, <dsaxena@...aro.org>,
	<arnd.bergmann@...aro.org>, <shawn.guo@...escale.com>,
	Jamie Iles <jamie@...ieiles.com>, <skannan@...cinc.com>,
	<linux@....linux.org.uk>, <jeremy.kerr@...onical.com>,
	<tglx@...utronix.de>, <linux-arm-kernel@...ts.infradead.org>,
	<sboyd@...inc.com>
Subject: Re: [PATCH v2 4/7] clk: Add simple gated clock

On Thu, Sep 22, 2011 at 03:26:59PM -0700, Mike Turquette wrote:
> From: Jeremy Kerr <jeremy.kerr@...onical.com>
> 
> Signed-off-by: Jeremy Kerr <jeremy.kerr@...onical.com>
> Signed-off-by: Mark Brown <broonie@...nsource.wolfsonmicro.com>
> Signed-off-by: Jamie Iles <jamie@...ieiles.com>
> Signed-off-by: Mike Turquette <mturquette@...com>
> ---
> Changes since v1:
> Add copyright header
> Fold in Jamie's patch for set-to-disable clks
> Use BIT macro instead of shift
> 
>  drivers/clk/Kconfig    |    4 ++
>  drivers/clk/Makefile   |    1 +
>  drivers/clk/clk-gate.c |   78 ++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/clk.h    |   13 ++++++++
>  4 files changed, 96 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/clk/clk-gate.c

I feel hard to tell the tree the clk parent, at register/init time. For the
simple gate clk, the only way is to set .get_parent. But normally, for clk
without any divider we set .get_parent to NULL. Maybe we can put .parent to
struct clk_hw?

Thanks
Richard
> 
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index d8313d7..a78967c 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -12,3 +12,7 @@ config GENERIC_CLK
>  config GENERIC_CLK_FIXED
>  	bool
>  	depends on GENERIC_CLK
> +
> +config GENERIC_CLK_GATE
> +	bool
> +	depends on GENERIC_CLK
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index 9a3325a..d186446 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -2,3 +2,4 @@
>  obj-$(CONFIG_CLKDEV_LOOKUP)	+= clkdev.o
>  obj-$(CONFIG_GENERIC_CLK)	+= clk.o
>  obj-$(CONFIG_GENERIC_CLK_FIXED)	+= clk-fixed.o
> +obj-$(CONFIG_GENERIC_CLK_GATE)	+= clk-gate.o
> diff --git a/drivers/clk/clk-gate.c b/drivers/clk/clk-gate.c
> new file mode 100644
> index 0000000..a1d8e79
> --- /dev/null
> +++ b/drivers/clk/clk-gate.c
> @@ -0,0 +1,78 @@
> +/*
> + * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@...onical.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * Simple clk gate implementation
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/module.h>
> +#include <asm/io.h>
> +
> +#define to_clk_gate(clk) container_of(clk, struct clk_gate, hw)
> +
> +static unsigned long clk_gate_get_rate(struct clk_hw *clk)
> +{
> +	return clk_get_rate(clk_get_parent(clk->clk));
> +}
> +
> +static void clk_gate_set_bit(struct clk_hw *clk)
> +{
> +	struct clk_gate *gate = to_clk_gate(clk);
> +	u32 reg;
> +
> +	reg = __raw_readl(gate->reg);
> +	reg |= BIT(gate->bit_idx);
> +	__raw_writel(reg, gate->reg);
> +}
> +
> +static void clk_gate_clear_bit(struct clk_hw *clk)
> +{
> +	struct clk_gate *gate = to_clk_gate(clk);
> +	u32 reg;
> +
> +	reg = __raw_readl(gate->reg);
> +	reg &= ~BIT(gate->bit_idx);
> +	__raw_writel(reg, gate->reg);
> +}
> +
> +static int clk_gate_enable_set(struct clk_hw *clk)
> +{
> +	clk_gate_set_bit(clk);
> +
> +	return 0;
> +}
> +
> +static void clk_gate_disable_clear(struct clk_hw *clk)
> +{
> +	clk_gate_clear_bit(clk);
> +}
> +
> +struct clk_hw_ops clk_gate_set_enable_ops = {
> +	.recalc_rate = clk_gate_get_rate,
> +	.enable = clk_gate_enable_set,
> +	.disable = clk_gate_disable_clear,
> +};
> +EXPORT_SYMBOL_GPL(clk_gate_set_enable_ops);
> +
> +static int clk_gate_enable_clear(struct clk_hw *clk)
> +{
> +	clk_gate_clear_bit(clk);
> +
> +	return 0;
> +}
> +
> +static void clk_gate_disable_set(struct clk_hw *clk)
> +{
> +	clk_gate_set_bit(clk);
> +}
> +
> +struct clk_hw_ops clk_gate_set_disable_ops = {
> +	.recalc_rate = clk_gate_get_rate,
> +	.enable = clk_gate_enable_clear,
> +	.disable = clk_gate_disable_set,
> +};
> +EXPORT_SYMBOL_GPL(clk_gate_set_disable_ops);
> diff --git a/include/linux/clk.h b/include/linux/clk.h
> index 1903dd8..626fd0d 100644
> --- a/include/linux/clk.h
> +++ b/include/linux/clk.h
> @@ -124,6 +124,19 @@ extern struct clk_hw_ops clk_fixed_ops;
>  
>  #endif /* CONFIG_GENERIC_CLK_FIXED */
>  
> +#ifdef CONFIG_GENERIC_CLK_GATE
> +
> +struct clk_gate {
> +	struct clk_hw	hw;
> +	void __iomem	*reg;
> +	u8		bit_idx;
> +};
> +
> +extern struct clk_hw_ops clk_gate_set_enable_ops;
> +extern struct clk_hw_ops clk_gate_set_disable_ops;
> +
> +#endif /* CONFIG_GENERIC_CLK_GATE */
> +
>  /**
>   * clk_register - register and initialize a new clock
>   *
> -- 
> 1.7.4.1
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

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