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    SubjectRe: [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@canonical.com>
    >
    > Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
    > Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
    > Signed-off-by: Jamie Iles <jamie@jamieiles.com>
    > Signed-off-by: Mike Turquette <mturquette@ti.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@canonical.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@lists.infradead.org
    > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
    >



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