[PATCH RFC v3 2/2] clk: Add handling of clk parent and rate assigned from DT

Bartlomiej Zolnierkiewicz
2014-03-27T17:19:51Z

Hi Sylwester,

On Thursday, March 27, 2014 01:16:19 PM Sylwester Nawrocki wrote:
> This function adds a helper function to configure clock parents and rates
> as specified in clock-parents, clock-rates DT properties for a consumer
> device and a call to it before driver is bound to a device.
>
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
> ---
> 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 | 26 ++++++
> drivers/base/dd.c | 7 ++
> drivers/clk/Makefile | 1 +
> drivers/clk/clk-conf.c | 87 ++++++++++++++++++++
> drivers/clk/clk.c | 10 ++-
> include/linux/clk/clk-conf.h | 19 +++++
> 6 files changed, 149 insertions(+), 1 deletion(-)
> 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 7c52c29..b452f80 100644
> --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt
> +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt
> @@ -115,3 +115,29 @@ 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 require static initial configuration of parts of the clocks
> +controller. Such a configuration can be specified in a clock consumer node
> +through clock-parents and clock-rates DT properties. The former should contain
> +a list of parent clocks in form of phandle and clock specifier pairs, the
> +latter the list of assigned clock frequency values (one cell each).
> +
> + uart at a000 {
> + compatible = "fsl,imx-uart";
> + reg = <0xa000 0x1000>;
> + ...
> + clocks = <&clkcon 0>, <&clkcon 3>;
> + clock-names = "baud", "mux";
> +
> + clock-parents = <0>, <&pll 1>;
> + clock-rates = <460800>;
> + };
> +
> +In this example the pll is set as parent of "mux" clock and frequency of "baud"
> +clock is specified as 460800 Hz.
> +
> +For clocks which are not directly connected to any consumer device similarly
> +clocks, clock-parents and/or clock-rates properties should be specified in
> +assigned-clocks subnode of a clock controller DT node.
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 0605176..4c633e7 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -25,6 +25,7 @@
> #include <linux/async.h>
> #include <linux/pm_runtime.h>
> #include <linux/pinctrl/devinfo.h>
> +#include <linux/clk/clk-conf.h>
>
> #include "base.h"
> #include "power/power.h"
> @@ -278,6 +279,12 @@ static int really_probe(struct device *dev, struct device_driver *drv)
> if (ret)
> goto probe_failed;
>
> + if (dev->of_node) {
> + ret = of_clk_device_init(dev->of_node);
> + if (ret)
> + goto probe_failed;
> + }
> +
> if (driver_sysfs_add(dev)) {
> printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
> __func__, dev_name(dev));
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index a367a98..c720e4b 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -8,6 +8,7 @@ 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
> +obj-$(CONFIG_COMMON_CLK) += clk-conf.o
>
> # 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..a2e992e
> --- /dev/null
> +++ b/drivers/clk/clk-conf.c
> @@ -0,0 +1,87 @@
> +/*
> + * Copyright (C) 2014 Samsung Electronics Co., Ltd.
> + * Sylwester Nawrocki <s.nawrocki@samsung.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.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/device.h>
> +#include <linux/of.h>
> +#include <linux/printk.h>
> +
> +/**
> + * of_clk_device_init() - parse and set clk configuration assigned to a device
> + * @node: device node to apply the configuration for
> + *
> + * This function parses 'clock-parents' and 'clock-rates' properties and sets
> + * any specified clock parents and rates.
> + */
> +int of_clk_device_init(struct device_node *node)
> +{
> + struct property *prop;
> + const __be32 *cur;
> + int rc, index, num_parents;
> + struct clk *clk, *pclk;
> + u32 rate;
> +
> + num_parents = of_count_phandle_with_args(node, "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++) {
> + pclk = of_clk_get_by_property(node, "clock-parents", index);
> + if (IS_ERR(pclk)) {
> + /* skip empty (null) phandles */
> + if (PTR_ERR(pclk) == -ENOENT)
> + continue;
> +
> + pr_warn("clk: couldn't get parent clock %d for %s\n",
> + index, node->full_name);
> + return PTR_ERR(pclk);
> + }
> +
> + clk = of_clk_get(node, index);
> + 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_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);
> + else
> + pr_debug("clk: set %s as parent of %s\n",
> + __clk_get_name(pclk), __clk_get_name(clk));
> + }
> +
> + index = 0;
> + of_property_for_each_u32(node, "clock-rates", prop, cur, rate) {
> + if (rate) {
> + clk = of_clk_get(node, index);
> + 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);
> + else
> + pr_debug("clk: set rate of clock %s to %lu\n",
> + __clk_get_name(clk), clk_get_rate(clk));
> + }
> + index++;
> + }
> +
> + return 0;
> +}
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 29dc1e7..240d776 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>
> @@ -2604,7 +2605,15 @@ 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);
> +
> + /* Set any assigned clock parents and rates */
> + np = of_get_child_by_name(clk_provider->np,
> + "assigned-clocks");
> + if (np)
> + of_clk_device_init(np);
> +
> list_del(&clk_provider->node);
> kfree(clk_provider);
> is_init_done = true;
> @@ -2619,7 +2628,6 @@ void __init of_clk_init(const struct of_device_id *matches)
> */
> if (!is_init_done)
> force = true;
> -
> }
> }
> #endif
> diff --git a/include/linux/clk/clk-conf.h b/include/linux/clk/clk-conf.h
> new file mode 100644
> index 0000000..f06b1c2
> --- /dev/null
> +++ b/include/linux/clk/clk-conf.h
> @@ -0,0 +1,19 @@
> +/*
> + * Copyright (C) 2014 Samsung Electronics Co., Ltd.
> + * Sylwester Nawrocki <s.nawrocki@samsung.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.
> + */
> +
> +struct device_node;
> +
> +#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
> +int of_clk_device_init(struct device_node *node);
> +#else
> +int of_clk_device_init(struct device_node *node)

It causes build brake with s3c6400_defconfig.

It should be marked with 'static inline' and clk-conf.c should be build
only for CONFIG_OF=y.

> +{
> + return 0;
> +}
> +#endif

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics