Re: [PATCHv9 09/43] CLK: ti: add support for ti divider-clock

[Tero Kristo <t-kristo@ti.com>]

On 10/31/2013 08:02 PM, Nishanth Menon wrote:
> On 10/25/2013 10:57 AM, Tero Kristo wrote:
>> This patch adds support for TI divider clock binding, which simply uses
>> the basic clock divider to provide the features needed.
>>
>> Signed-off-by: Tero Kristo <t-kristo@ti.com>
>> ---
>>   .../devicetree/bindings/clock/ti/divider.txt       |   86 +++++++
>>   drivers/clk/ti/Makefile                            |    3 +-
>>   drivers/clk/ti/divider.c                           |  239 ++++++++++++++++++++
>>   3 files changed, 327 insertions(+), 1 deletion(-)
>>   create mode 100644 Documentation/devicetree/bindings/clock/ti/divider.txt
>>   create mode 100644 drivers/clk/ti/divider.c
>>
>> diff --git a/Documentation/devicetree/bindings/clock/ti/divider.txt b/Documentation/devicetree/bindings/clock/ti/divider.txt
>> new file mode 100644
>> index 0000000..65e3dcd
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/clock/ti/divider.txt
>> @@ -0,0 +1,86 @@
>> +Binding for TI divider clock
>> +
>> +Binding status: Unstable - ABI compatibility may be broken in the future
>> +
>> +This binding uses the common clock binding[1].  It assumes a
>> +register-mapped adjustable clock rate divider that does not gate and has
>> +only one input clock or parent.  By default the value programmed into
>> +the register is one less than the actual divisor value.  E.g:
>> +
>> +register value		actual divisor value
>> +0			1
>> +1			2
>> +2			3
>> +
>> +This assumption may be modified by the following optional properties:
>> +
>> +ti,index-starts-at-one - valid divisor values start at 1, not the default
>> +of 0.  E.g:
>> +register value		actual divisor value
>> +1			1
>> +2			2
>> +3			3
>> +
>> +ti,index-power-of-two - valid divisor values are powers of two.  E.g:
>> +register value		actual divisor value
>> +0			1
>> +1			2
>> +2			4
>> +
>> +Additionally an array of valid dividers may be supplied like so:
>> +
>> +	dividers = <4>, <8>, <0>, <16>;
> ti,dividers I believe.

True.

>
>> +
>> +Which will map the resulting values to a divisor table by their index:
>> +register value		actual divisor value
>> +0			4
>> +1			8
>> +2			<invalid divisor, skipped>
>> +3			16
>> +
>> +Any zero value in this array means the corresponding bit-value is invalid
>> +and must not be used.
>> +
>> +The binding must also provide the register to control the divider and
>> +unless the divider array is provided, min and max dividers. Optionally
>> +the number of bits to shift that mask, if necessary. If the shift value
>> +is missing it is the same as supplying a zero shift.
>> +
>> +Required properties:
>> +- compatible : shall be "ti,divider-clock".
>
> ti,composite-divider-clock undocumented?

Hmm yea true.

>
>> +- #clock-cells : from common clock binding; shall be set to 0.
>> +- clocks : link to phandle of parent clock
>> +- reg : offset for register controlling adjustable divider
>> +
>> +Optional properties:
>> +- clock-output-names : from common clock binding.
>> +- ti,dividers : array of integers defining divisors
>> +- ti,bit-shift : number of bits to shift the divider value, defaults to 0
>> +- ti,min-div : min divisor for dividing the input clock rate, only
>> +  needed if the first divisor is offset from the default value (1)
>> +- ti,max-div : max divisor for dividing the input clock rate, only needed
>> +  if ti,dividers is not defined.
>> +- ti,index-starts-at-one : valid divisor programming starts at 1, not zero
>
> makes sense only if ti,dividers are not defined, right?
> CLK_DIVIDER_ONE_BASED is used with !table

Yeah, ignored if table is present.

>
>> +- ti,index-power-of-two : valid divisor programming must be a power of two
>
> makes sense only if ti,dividers are not defined, right?
> CLK_DIVIDER_POWER_OF_TWO is used with !table

Yea.

>
>> +- ti,autoidle-shift : bit shift of the autoidle enable bit for the clock
>> +- ti,invert-autoidle-bit : autoidle is enabled by setting the bit to 0
>
> These are part of auto idle driver bindings, so maybe give a link to that?

Yea can do.

>
>> +- ti,set-rate-parent : clk_set_rate is propagated to parent
>
> yeah - this is one of those properties that should probably become
> generic at a later point in time.
>
>> +
>> +Examples:
>> +dpll_usb_m2_ck: dpll_usb_m2_ck@4a008190 {
>> +	#clock-cells = <0>;
>> +	compatible = "ti,divider-clock";
>> +	clocks = <&dpll_usb_ck>;
>> +	ti,max-div = <127>;
>> +	reg = <0x190>;
>> +	ti,index-starts-at-one;
>> +};
>> +
>> +aess_fclk: aess_fclk@4a004528 {
>> +	#clock-cells = <0>;
>> +	compatible = "ti,divider-clock";
>> +	clocks = <&abe_clk>;
>> +	ti,bit-shift = <24>;
>> +	reg = <0x528>;
>> +	ti,max-div = <2>;
>> +};
>
> an example of ti,dividers will be useful as well.

Ok.

>
>> diff --git a/drivers/clk/ti/Makefile b/drivers/clk/ti/Makefile
>> index a4a7595..640ebf9 100644
>> --- a/drivers/clk/ti/Makefile
>> +++ b/drivers/clk/ti/Makefile
>> @@ -1,3 +1,4 @@
>>   ifneq ($(CONFIG_OF),)
>> -obj-y					+= clk.o dpll.o autoidle.o composite.o
>> +obj-y					+= clk.o dpll.o autoidle.o divider.o \
>> +					   composite.o
>>   endif
>> diff --git a/drivers/clk/ti/divider.c b/drivers/clk/ti/divider.c
>> new file mode 100644
>> index 0000000..787bc8f
>> --- /dev/null
>> +++ b/drivers/clk/ti/divider.c
>> @@ -0,0 +1,239 @@
>> +/*
>> + * TI Divider Clock
>> + *
>> + * Copyright (C) 2013 Texas Instruments, Inc.
>> + *
>> + * Tero Kristo <t-kristo@ti.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.
>> + *
>> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
>> + * kind, whether express or implied; without even the implied warranty
>> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +#include <linux/clk-provider.h>
>> +#include <linux/slab.h>
>> +#include <linux/err.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/clk/ti.h>
>> +
>> +static struct clk_div_table
>> +__init *ti_clk_get_div_table(struct device_node *node)
>> +{
>> +	struct clk_div_table *table;
>> +	const __be32 *divspec;
>> +	u32 val;
>> +	u32 num_div;
>> +	u32 valid_div;
>> +	int i;
>> +
>> +	divspec = of_get_property(node, "ti,dividers", &num_div);
>> +
>> +	if (!divspec)
>> +		return NULL;
>> +
>> +	num_div /= 4;
>> +
>> +	valid_div = 0;
>> +
>> +	/* Determine required size for divider table */
>> +	for (i = 0; i < num_div; i++) {
>> +		of_property_read_u32_index(node, "ti,dividers", i, &val);
>> +		if (val)
>> +			valid_div++;
>> +	}
>> +
>> +	if (!valid_div) {
>> +		pr_err("%s: no valid dividers for %s table\n", __func__,
>> +		       node->name);
>> +		return ERR_PTR(-EINVAL);
>> +	}
>> +
>> +	table = kzalloc(sizeof(*table) * (valid_div + 1), GFP_KERNEL);
>> +
>> +	if (!table) {
>> +		pr_err("%s: unable to allocate memory for %s table\n", __func__,
>> +		       node->name);
>
> you could drop this.

True.

>
>> +		return ERR_PTR(-ENOMEM);
>> +	}
>> +
>> +	valid_div = 0;
>> +
>> +	for (i = 0; i < num_div; i++) {
>> +		of_property_read_u32_index(node, "ti,dividers", i, &val);
>> +		if (val) {
>> +			table[valid_div].div = val;
>> +			table[valid_div].val = i;
>> +			valid_div++;
>> +		}
>> +	}
>> +
>> +	return table;
>> +}
>> +
>> +static int _get_divider_width(struct device_node *node,
>> +			      const struct clk_div_table *table,
>> +			      u8 flags)
>> +{
>> +	u32 min_div;
>> +	u32 max_div;
>> +	u32 val = 0;
>> +	u32 div;
>> +
>> +	if (!table) {
>> +		/* Clk divider table not provided, determine min/max divs */
>> +		if (of_property_read_u32(node, "ti,min-div", &min_div)) {
>> +			pr_debug("%s: no min-div for %s, default=1\n",
>> +				 __func__, node->name);
>> +			min_div = 1;
>> +		}
>> +
>> +		if (of_property_read_u32(node, "ti,max-div", &max_div)) {
>> +			pr_err("%s: no max-div for %s!\n", __func__,
>> +			       node->name);
>> +			return -EINVAL;
>
> will be nice to get warning if ti,divider is defined and any of the
> non-operational properties are defined as well.

Hmm ok, can add checks for those.

>
>> +		}
>> +
>> +		/* Determine bit width for the field */
>> +		if (flags & CLK_DIVIDER_ONE_BASED)
>> +			val = 1;
>> +
>> +		div = min_div;
>> +
>> +		while (div < max_div) {
>> +			if (flags & CLK_DIVIDER_POWER_OF_TWO)
>> +				div <<= 1;
>> +			else
>> +				div++;
>> +			val++;
>> +		}
>> +	} else {
>> +		div = 0;
>> +
>> +		while (table[div].div) {
>> +			val = table[div].val;
>> +			div++;
>> +		}
>> +	}
>> +
>> +	return fls(val);
>> +}
>> +
>> +/**
>> + * of_ti_divider_clk_setup() - Setup function for simple div rate clock
>> + */
>> +static int __init of_ti_divider_clk_setup(struct device_node *node,
>> +					  struct regmap *regmap)
>> +{
>> +	struct clk *clk;
>> +	const char *clk_name = node->name;
>> +	void __iomem *reg;
>> +	const char *parent_name;
>> +	u8 clk_divider_flags = 0;
>> +	u8 width = 0;
>> +	u8 shift = 0;
>> +	struct clk_div_table *table = NULL;
>> +	u32 val = 0;
>> +	u32 flags = 0;
>> +	int ret = 0;
>> +
>> +	parent_name = of_clk_get_parent_name(node, 0);
>> +
>> +	if (of_property_read_u32(node, "reg", &val)) {
>> +		pr_err("%s: %s must have reg\n", __func__, clk_name);
>> +		return -EINVAL;
>> +	}
>> +
>> +	reg = (void *)val;
>> +
>> +	if (!of_property_read_u32(node, "ti,bit-shift", &val))
>> +		shift = val;
>> +
>> +	if (of_property_read_bool(node, "ti,index-starts-at-one"))
>> +		clk_divider_flags |= CLK_DIVIDER_ONE_BASED;
>> +
>> +	if (of_property_read_bool(node, "ti,index-power-of-two"))
>> +		clk_divider_flags |= CLK_DIVIDER_POWER_OF_TWO;
>> +
>> +	if (of_property_read_bool(node, "ti,set-rate-parent"))
>> +		flags |= CLK_SET_RATE_PARENT;
>> +
>> +	table = ti_clk_get_div_table(node);
>> +
>> +	if (IS_ERR(table))
>> +		return PTR_ERR(table);
>> +
>> +	ret = _get_divider_width(node, table, clk_divider_flags);
>> +	if (ret < 0)
>> +		goto cleanup;
>> +
>> +	width = ret;
>> +
>> +	clk = clk_register_divider_table_regmap(NULL, clk_name, parent_name,
>> +						flags, reg, regmap, shift,
>> +						width, clk_divider_flags, table,
>> +						NULL);
>> +
>> +	if (!IS_ERR(clk)) {
>> +		of_clk_add_provider(node, of_clk_src_simple_get, clk);
>> +		ret = of_ti_autoidle_setup(node, regmap);
>
> if this fails, table will be freed though, we have added provider and
> registerd table_regmap, no?

Provider and regmap are shared for the whole IP block (CM/PRM whatever.) 
Those are only initialized once.

>
>> +	} else {
>> +		ret = PTR_ERR(clk);
>> +	}
>> +
>> +	if (!ret)
>> +		return 0;
>> +cleanup:
>> +	kfree(table);
>> +	return ret;
>> +}
>> +CLK_OF_DECLARE(divider_clk, "ti,divider-clock", of_ti_divider_clk_setup);
>> +
>> +static int __init of_ti_composite_divider_clk_setup(struct device_node *node,
>> +						     struct regmap *regmap)
>> +{
>> +	struct clk_divider *div;
>> +	u32 val;
>> +	int ret;
>> +
>> +	div = kzalloc(sizeof(*div), GFP_KERNEL);
>> +	if (!div)
>> +		return -ENOMEM;
>> +
>> +	of_property_read_u32(node, "reg", &val);
>
> reg is a mandatory property, no? error checks?

Ok can add. :P

>
>> +	div->reg = (void *)val;
>> +	div->regmap = regmap;
>> +
>> +	div->table = ti_clk_get_div_table(node);
>> +
>> +	if (of_property_read_bool(node, "ti,index-starts-at-one"))
>> +		div->flags |= CLK_DIVIDER_ONE_BASED;
>
> alright, this does not really map back to ti,divder-clock style
> handling.. aren't they supposed to be consistent?
> how about "ti,index-power-of-two", bit shift etc?

I can add non-used property checks yes.

>> +
>> +	ret = _get_divider_width(node, div->table, div->flags);
>> +	if (ret < 0)
>> +		goto cleanup;
>> +
>> +	div->width = ret;
>> +
>> +	if (of_property_read_u32(node, "ti,bit-shift", &val)) {
>> +		pr_debug("%s: missing bit-shift property for %s, default=0\n",
>> +			 __func__, node->name);
>> +		val = 0;
>> +	}
>> +	div->shift = val;
>> +
>> +	ret = ti_clk_add_component(node, &div->hw, CLK_COMPONENT_TYPE_DIVIDER);
>> +	if (!ret)
>> +		return 0;
>> +
>> +cleanup:
>> +	kfree(div);
>> +	return ret;
>> +}
>> +CLK_OF_DECLARE(ti_composite_divider_clk, "ti,composite-divider-clock",
>> +	       of_ti_composite_divider_clk_setup);
>>
>
>