Re: [PATCH/RFC V8 1/1] clk: Support for clock parents and rates assigned from device tree

[Sylwester Nawrocki]

On 18/06/14 17:29, Sylwester Nawrocki wrote:
> This patch adds helper functions to configure clock parents and rates
> as specified through 'assigned-clock-parents', 'assigned-clock-rates'
> DT properties for a clock provider or clock consumer device.
> The helpers are now being called by the bus code for the platform, I2C
> and SPI busses, before the driver probing and also in the clock core
> after registration of a clock provider.
> 
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
> Acked-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>

Could someone please take a look and review that patch ?
Any further suggestions, ACKs/NAKs ?

I would appreciate a DT, SPI or the I2C maintainer opinions.

Thanks,
Sylwester
> ---
> Changes since v6:
>  - use a set of separate DT properties to specify the default parent
>    clocks and rates;
>  - the clock defaults setting extended to the I2C and SPI busses.
> 
> Changes since v5:
>  - updated the DT binding description (dropped 'assigned-clocks' node);
>  - fixed detecting of null phandles (ENOENT error handling);
>  - modified of_clk_init() to account for that the clocks property may now
>    contain a clock specifier with a phandle that points to our node;
> 
> Changes since v4:
>  - added note explaining how to skip setting parent and rate
>    of a clock,
>  - moved of_clk_dev_init() calls to the platform bus,
>  - added missing call to of_node_put(),
>  - dropped debug traces.
> 
> Changes since v3:
>  - added detailed description of the assigned-clocks subnode,
>  - added missing 'static inline' to the function stub definition,
>  - clk-conf.c is now excluded when CONFIG_OF is not set,
>  - s/of_clk_device_setup/of_clk_device_init.
> 
> Changes since v2:
>  - edited in clock-bindings.txt, added note about 'assigned-clocks'
>    subnode which may be used to specify "global" clocks configuration
>    at a clock provider node,
>  - moved of_clk_device_setup() function declaration from clk-provider.h
>    to clk-conf.h so required function stubs are available when
>    CONFIG_COMMON_CLK is not enabled,
> 
> Changes since v1:
>  - the helper function to parse and set assigned clock parents and
>    rates made public so it is available to clock providers to call
>    directly;
>  - dropped the platform bus notification and call of_clk_device_setup()
>    is is now called from the driver core, rather than from the
>    notification callback;
>  - s/of_clk_get_list_entry/of_clk_get_by_property.
> ---
>  .../devicetree/bindings/clock/clock-bindings.txt   |   36 +++++
>  drivers/base/platform.c                            |    5 +
>  drivers/clk/Makefile                               |    3 +
>  drivers/clk/clk-conf.c                             |  143 ++++++++++++++++++++
>  drivers/clk/clk.c                                  |   12 +-
>  drivers/i2c/i2c-core.c                             |    5 +
>  drivers/spi/spi.c                                  |    5 +
>  include/linux/clk/clk-conf.h                       |   20 +++
>  8 files changed, 227 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/clk/clk-conf.c
>  create mode 100644 include/linux/clk/clk-conf.h
> 
> diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt
> index f1578781..06fc6d5 100644
> --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt
> +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt
> @@ -131,3 +131,39 @@ clock signal, and a UART.
>    ("pll" and "pll-switched").
>  * The UART has its baud clock connected the external oscillator and its
>    register clock connected to the PLL clock (the "pll-switched" signal)
> +
> +==Assigned clock parents and rates==
> +
> +Some platforms may require initial configuration of default parent clocks
> +and clock frequencies. Such a configuration can be specified in a device tree
> +node through assigned-clocks, assigned-clock-parents and assigned-clock-rates
> +properties. The assigned-clock-parents property should contain a list of parent
> +clocks in form of phandle and clock specifier pairs, the assigned-clock-parents
> +property the list of assigned clock frequency values - corresponding to clocks
> +listed in the assigned-clocks property.
> +
> +To skip setting parent or rate of a clock its corresponding entry should be
> +set to 0, or can be omitted if it is not followed by any non-zero entry.
> +
> +    uart@a000 {
> +        compatible = "fsl,imx-uart";
> +        reg = <0xa000 0x1000>;
> +        ...
> +        clocks = <&osc 0>, <&pll 1>;
> +        clock-names = "baud", "register";
> +
> +        assigned-clocks = <&clkcon 0>, <&pll 2>;
> +        assigned-clock-parents = <&pll 2>;
> +        assigned-clock-rates = <0>, <460800>;
> +    };
> +
> +In this example the <&pll 2> clock is set as parent of clock <&clkcon 0> and
> +the <&pll 2> clock is assigned a frequency value of 460800 Hz.
> +
> +Configuring a clock's parent and rate through the device node that consumes
> +the clock can be done only for clocks that have a single user. Specifying
> +conflicting parent or rate configuration in multiple consumer nodes for
> +a shared clock is forbidden.
> +
> +Configuration of common clocks, which affect multiple consumer devices can
> +be similarly specified in the clock provider node.
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 5b47210..f622733 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -23,6 +23,7 @@
>  #include <linux/pm_runtime.h>
>  #include <linux/idr.h>
>  #include <linux/acpi.h>
> +#include <linux/clk/clk-conf.h>
> 
>  #include "base.h"
>  #include "power/power.h"
> @@ -486,6 +487,10 @@ static int platform_drv_probe(struct device *_dev)
>  	struct platform_device *dev = to_platform_device(_dev);
>  	int ret;
> 
> +	ret = of_clk_set_defaults(_dev->of_node, false);
> +	if (ret < 0)
> +		return ret;
> +
>  	acpi_dev_pm_attach(_dev, true);
> 
>  	ret = drv->probe(dev);
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index b25a1fe..7fe358c 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -8,6 +8,9 @@ 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
> +ifeq ($(CONFIG_OF), y)
> +obj-$(CONFIG_COMMON_CLK)	+= clk-conf.o
> +endif
> 
>  # hardware specific clock types
>  # please keep this section sorted lexicographically by file/directory path name
> diff --git a/drivers/clk/clk-conf.c b/drivers/clk/clk-conf.c
> new file mode 100644
> index 0000000..1f73019
> --- /dev/null
> +++ b/drivers/clk/clk-conf.c
> @@ -0,0 +1,143 @@
> +/*
> + * Copyright (C) 2014 Samsung Electronics Co., Ltd.
> + * Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
> + *
> + * 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.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/clk/clk-conf.h>
> +#include <linux/device.h>
> +#include <linux/of.h>
> +#include <linux/printk.h>
> +#include "clk.h"
> +
> +static int __set_clk_parents(struct device_node *node, bool clk_supplier)
> +{
> +	struct of_phandle_args clkspec;
> +	int index, rc, num_parents;
> +	struct clk *clk, *pclk;
> +
> +	num_parents = of_count_phandle_with_args(node, "assigned-clock-parents",
> +						 "#clock-cells");
> +	if (num_parents == -EINVAL)
> +		pr_err("clk: invalid value of clock-parents property at %s\n",
> +		       node->full_name);
> +
> +	for (index = 0; index < num_parents; index++) {
> +		rc = of_parse_phandle_with_args(node, "assigned-clock-parents",
> +					"#clock-cells",	index, &clkspec);
> +		if (rc < 0) {
> +			/* skip empty (null) phandles */
> +			if (rc == -ENOENT)
> +				continue;
> +			else
> +				return rc;
> +		}
> +		if (clkspec.np == node && !clk_supplier)
> +			return 0;
> +		pclk = of_clk_get_by_clkspec(&clkspec);
> +		if (IS_ERR(pclk)) {
> +			pr_warn("clk: couldn't get parent clock %d for %s\n",
> +				index, node->full_name);
> +			return PTR_ERR(pclk);
> +		}
> +
> +		rc = of_parse_phandle_with_args(node, "assigned-clocks",
> +					"#clock-cells", index, &clkspec);
> +		if (rc < 0)
> +			goto err;
> +		if (clkspec.np == node && !clk_supplier) {
> +			rc = 0;
> +			goto err;
> +		}
> +		clk = of_clk_get_by_clkspec(&clkspec);
> +		if (IS_ERR(pclk)) {
> +			pr_warn("clk: couldn't get parent clock %d for %s\n",
> +				index, node->full_name);
> +			rc = PTR_ERR(pclk);
> +			goto err;
> +		}
> +
> +		rc = clk_set_parent(clk, pclk);
> +		if (rc < 0)
> +			pr_err("clk: failed to reparent %s to %s: %d\n",
> +			       __clk_get_name(clk), __clk_get_name(pclk), rc);
> +		clk_put(clk);
> +		clk_put(pclk);
> +	}
> +	return 0;
> +err:
> +	clk_put(pclk);
> +	return rc;
> +}
> +
> +static int __set_clk_rates(struct device_node *node, bool clk_supplier)
> +{
> +	struct of_phandle_args clkspec;
> +	struct property	*prop;
> +	const __be32 *cur;
> +	int rc, index = 0;
> +	struct clk *clk;
> +	u32 rate;
> +
> +	of_property_for_each_u32(node, "assigned-clock-rates", prop, cur, rate) {
> +		if (rate) {
> +			rc = of_parse_phandle_with_args(node, "assigned-clocks",
> +					"#clock-cells",	index, &clkspec);
> +			if (rc < 0) {
> +				/* skip empty (null) phandles */
> +				if (rc == -ENOENT)
> +					continue;
> +				else
> +					return rc;
> +			}
> +			if (clkspec.np == node && !clk_supplier)
> +				return 0;
> +
> +			clk = of_clk_get_by_clkspec(&clkspec);
> +			if (IS_ERR(clk)) {
> +				pr_warn("clk: couldn't get clock %d for %s\n",
> +					index, node->full_name);
> +				return PTR_ERR(clk);
> +			}
> +
> +			rc = clk_set_rate(clk, rate);
> +			if (rc < 0)
> +				pr_err("clk: couldn't set %s clock rate: %d\n",
> +				       __clk_get_name(clk), rc);
> +			clk_put(clk);
> +		}
> +		index++;
> +	}
> +	return 0;
> +}
> +
> +/**
> + * of_clk_set_defaults() - parse and set assigned clocks configuration
> + * @node: device node to apply clock settings for
> + * @clk_supplier: true if clocks supplied by @node should also be considered
> + *
> + * This function parses 'assigned-{clocks/clock-parents/clock-rates}' properties
> + * and sets any specified clock parents and rates. The @clk_supplier argument
> + * should be set to true if @node may be also a clock supplier of any clock
> + * listed in its 'assigned-clocks' or 'assigned-clock-parents' properties.
> + * If @clk_supplier is false the function exits returnning 0 as soon as it
> + * determines the @node is also a supplier of any of the clocks.
> + */
> +int of_clk_set_defaults(struct device_node *node, bool clk_supplier)
> +{
> +	int rc;
> +
> +	if (!node)
> +		return 0;
> +
> +	rc = __set_clk_parents(node, clk_supplier);
> +	if (rc < 0)
> +		return rc;
> +
> +	return __set_clk_rates(node, clk_supplier);
> +}
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 8b73ede..a77af45 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -10,6 +10,7 @@
>   */
> 
>  #include <linux/clk-private.h>
> +#include <linux/clk/clk-conf.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
>  #include <linux/spinlock.h>
> @@ -2414,6 +2415,7 @@ int of_clk_add_provider(struct device_node *np,
>  			void *data)
>  {
>  	struct of_clk_provider *cp;
> +	int ret;
> 
>  	cp = kzalloc(sizeof(struct of_clk_provider), GFP_KERNEL);
>  	if (!cp)
> @@ -2428,7 +2430,11 @@ int of_clk_add_provider(struct device_node *np,
>  	mutex_unlock(&of_clk_mutex);
>  	pr_debug("Added clock from %s\n", np->full_name);
> 
> -	return 0;
> +	ret = of_clk_set_defaults(np, true);
> +	if (ret < 0)
> +		of_clk_del_provider(np);
> +
> +	return ret;
>  }
>  EXPORT_SYMBOL_GPL(of_clk_add_provider);
> 
> @@ -2605,7 +2611,10 @@ void __init of_clk_init(const struct of_device_id *matches)
>  		list_for_each_entry_safe(clk_provider, next,
>  					&clk_provider_list, node) {
>  			if (force || parent_ready(clk_provider->np)) {
> +
>  				clk_provider->clk_init_cb(clk_provider->np);
> +				of_clk_set_defaults(clk_provider->np, true);
> +
>  				list_del(&clk_provider->node);
>  				kfree(clk_provider);
>  				is_init_done = true;
> @@ -2620,7 +2629,6 @@ void __init of_clk_init(const struct of_device_id *matches)
>  		 */
>  		if (!is_init_done)
>  			force = true;
> -
>  	}
>  }
>  #endif
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index 7c7f4b8..66aa83b 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -42,6 +42,7 @@
>  #include <linux/of.h>
>  #include <linux/of_device.h>
>  #include <linux/of_irq.h>
> +#include <linux/clk/clk-conf.h>
>  #include <linux/completion.h>
>  #include <linux/hardirq.h>
>  #include <linux/irqflags.h>
> @@ -274,6 +275,10 @@ static int i2c_device_probe(struct device *dev)
>  					client->flags & I2C_CLIENT_WAKE);
>  	dev_dbg(dev, "probe\n");
> 
> +	status = of_clk_set_defaults(dev->of_node, false);
> +	if (status < 0)
> +		return status;
> +
>  	acpi_dev_pm_attach(&client->dev, true);
>  	status = driver->probe(client, i2c_match_id(driver->id_table, client));
>  	if (status)
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index 939edf4..8374620 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -29,6 +29,7 @@
>  #include <linux/mutex.h>
>  #include <linux/of_device.h>
>  #include <linux/of_irq.h>
> +#include <linux/clk/clk-conf.h>
>  #include <linux/slab.h>
>  #include <linux/mod_devicetable.h>
>  #include <linux/spi/spi.h>
> @@ -259,6 +260,10 @@ static int spi_drv_probe(struct device *dev)
>  	const struct spi_driver		*sdrv = to_spi_driver(dev->driver);
>  	int ret;
> 
> +	ret = of_clk_set_defaults(dev->of_node, false);
> +	if (ret)
> +		return ret;
> +
>  	acpi_dev_pm_attach(dev, true);
>  	ret = sdrv->probe(to_spi_device(dev));
>  	if (ret)
> diff --git a/include/linux/clk/clk-conf.h b/include/linux/clk/clk-conf.h
> new file mode 100644
> index 0000000..f3050e1
> --- /dev/null
> +++ b/include/linux/clk/clk-conf.h
> @@ -0,0 +1,20 @@
> +/*
> + * Copyright (C) 2014 Samsung Electronics Co., Ltd.
> + * Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
> + *
> + * 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.
> + */
> +
> +struct device_node;
> +
> +#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
> +int of_clk_set_defaults(struct device_node *node, bool clk_supplier);
> +#else
> +static inline int of_clk_set_defaults(struct device_node *node,
> +				      bool clk_supplier)
> +{
> +	return 0;
> +}
> +#endif
> --
> 1.7.9.5
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