Subject: [PATCHv9 11/43] CLK: TI: add support for gate clock

From: [email-masked] (Nishanth Menon)
Date: Fri, 1 Nov 2013 15:11:39 -0500

On 10/25/2013 10:57 AM, Tero Kristo wrote:
> This patch adds support for TI specific gate clocks. These behave as basic
> gate-clock, but have different ops / hw-ops for controlling the actual
> gate, for example waiting until the clock is ready. Several sub-types
> are supported:
> - ti,gate-clock: basic gate clock with default ops/hwops
> - ti,clkdm-gate-clock: clockdomain level gate control
> - ti,dss-gate-clock: gate clock with DSS specific hardware handling
> - ti,am35xx-gate-clock: gate clock with AM35xx specific hardware handling
> - ti,hsdiv-gate-clock: gate clock with OMAP36xx hardware errata handling
> 
> Signed-off-by: Tero Kristo <[email-masked]>
> ---
>  .../devicetree/bindings/clock/ti/gate.txt          |   77 ++++++
>  arch/arm/mach-omap2/clock.h                        |   29 ---
>  drivers/clk/ti/Makefile                            |    2 +-
>  drivers/clk/ti/gate.c                              |  258 ++++++++++++++++++++
>  include/linux/clk/ti.h                             |   36 +++
>  5 files changed, 372 insertions(+), 30 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/clock/ti/gate.txt
>  create mode 100644 drivers/clk/ti/gate.c
> 
> diff --git a/Documentation/devicetree/bindings/clock/ti/gate.txt b/Documentation/devicetree/bindings/clock/ti/gate.txt
> new file mode 100644
> index 0000000..18c4d86
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/ti/gate.txt
> @@ -0,0 +1,77 @@
> +Binding for Texas Instruments gate clock.
> +
> +Binding status: Unstable - ABI compatibility may be broken in the future
> +
> +This binding uses the common clock binding[1]. This clock is
> +quite much similar to the basic gate-clock [2], however,
> +it supports a number of additional features. If no register
> +is provided for this clock, the code assumes that a clockdomain
> +will be controlled instead and the corresponding hw-ops for
> +that is used.
> +
> +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
> +[2] Documentation/devicetree/bindings/clock/gate-clock.txt
> +[3] Documentation/devicetree/bindings/clock/ti/clockdomain.txt

i think you may want to sequence patch #12 before this if you would
like to refer to this.

> +
> +Required properties:
> +- compatible : shall be one of:
> +  "ti,gate-clock" - basic gate clock
> +  "ti,wait-gate-clock" - gate clock which waits until clock is active before
> +			 returning from clk_enable()
an example will be nice for this.

[...]
> diff --git a/drivers/clk/ti/gate.c b/drivers/clk/ti/gate.c
> new file mode 100644
> index 0000000..1a201f8
> --- /dev/null
> +++ b/drivers/clk/ti/gate.c

[...]
> +/**
> + * omap36xx_gate_clk_enable_with_hsdiv_restore - enable clocks suffering
> + *         from HSDivider PWRDN problem Implements Errata ID: i556.
> + * @clk: DPLL output struct clk
> + *
> + * 3630 only: dpll3_m3_ck, dpll4_m2_ck, dpll4_m3_ck, dpll4_m4_ck,
> + * dpll4_m5_ck & dpll4_m6_ck dividers gets loaded with reset
> + * valueafter their respective PWRDN bits are set.  Any dummy write
> + * (Any other value different from the Read value) to the
> + * corresponding CM_CLKSEL register will refresh the dividers.
> + */
> +static int omap36xx_gate_clk_enable_with_hsdiv_restore(struct clk_hw *clk)
> +{
> +	struct clk_divider *parent;
> +	struct clk_hw *parent_hw;
> +	u32 dummy_v, orig_v;
> +	int ret;
> +
> +	/* Clear PWRDN bit of HSDIVIDER */
> +	ret = omap2_dflt_clk_enable(clk);
> +
> +	/* Parent is the x2 node, get parent of parent for the m2 div */
> +	parent_hw = __clk_get_hw(__clk_get_parent(__clk_get_parent(clk->clk)));
> +	parent = to_clk_divider(parent_hw);
> +
> +	/* Restore the dividers */
> +	if (!ret) {
> +		orig_v = __raw_readl(parent->reg);
> +		dummy_v = orig_v;
> +
> +		/* Write any other value different from the Read value */
> +		dummy_v ^= (1 << parent->shift);
> +		__raw_writel(dummy_v, parent->reg);
> +
> +		/* Write the original divider */
> +		__raw_writel(orig_v, parent->reg);

i think we already did state that these need to be regmap_updatebits..

> +	}
> +
> +	return ret;
> +}
> +
> +static int __init _of_ti_gate_clk_setup(struct device_node *node,
> +					const struct clk_ops *ops,
> +					const struct clk_hw_omap_ops *hw_ops,
> +					struct regmap *regmap)
> +{
> +	struct clk *clk;
> +	struct clk_init_data init = { NULL };
> +	struct clk_hw_omap *clk_hw;
> +	const char *clk_name = node->name;
> +	const char *parent_name;
> +	u32 val;
> +
> +	clk_hw = kzalloc(sizeof(*clk_hw), GFP_KERNEL);
> +	if (!clk_hw) {
> +		pr_err("%s: could not allocate clk_hw_omap\n", __func__);
> +		return -ENOMEM;
> +	}
> +
> +	clk_hw->hw.init = &init;
> +
> +	of_property_read_string(node, "clock-output-names", &clk_name);
> +
> +	init.name = clk_name;
> +	init.ops = ops;
> +
> +	if (!of_property_read_u32(node, "reg", &val))
> +		clk_hw->enable_reg = (void *)val;

seems reg is a mandatory as per bindings for everything other than
ti,clkdm-gate-clock.. no error handling?

> +
> +	clk_hw->regmap = regmap;
> +
> +	if (!of_property_read_u32(node, "ti,bit-shift", &val))
> +		clk_hw->enable_bit = val;

Again -> bindings state this is mandatory for non ti,clkdm-gate-clock
clocks. no error handling?

> +	clk_hw->ops = hw_ops;
> +
> +	parent_name = of_clk_get_parent_name(node, 0);
> +	init.parent_names = &parent_name;
> +	init.num_parents = 1;

error checks for parent clk which seems to be mandatory?

> +
> +	if (of_property_read_bool(node, "ti,set-rate-parent"))
> +		init.flags |= CLK_SET_RATE_PARENT;
> +
> +	if (of_property_read_bool(node, "ti,set-bit-to-disable"))
> +		clk_hw->flags |= INVERT_ENABLE;
> +
> +	clk = clk_register(NULL, &clk_hw->hw);
> +
> +	if (!IS_ERR(clk)) {
> +		of_clk_add_provider(node, of_clk_src_simple_get, clk);
> +		return 0;
> +	}
> +

free(clk_hw)?

> +	return PTR_ERR(clk);
> +}
> +

-- 
Regards,
Nishanth Menon