Messages in this thread | | | Date | Mon, 14 Nov 2011 10:14:00 +0800 | From | Richard Zhao <> | Subject | Re: [RFC 6/8] of: add clock providers |
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On Tue, Nov 08, 2011 at 08:49:42PM -0600, Rob Herring wrote: > On 11/08/2011 07:19 PM, Grant Likely wrote: > > Based on work by Ben Herrenschmidt and Jeremy Kerr, this patch adds an > > of_clk_get function to allow platforms to retrieve clock data from the > > device tree. > > > > Platform register a provider through of_clk_add_provider, which will be > > called when a device references the provider's OF node for a clock > > reference. > > > > Signed-off-by: Grant Likely <grant.likely@secretlab.ca> > > --- > > .../devicetree/bindings/clock/clock-bindings.txt | 109 +++++++++++++++++ > > drivers/of/Kconfig | 6 + > > drivers/of/Makefile | 1 + > > drivers/of/clock.c | 129 ++++++++++++++++++++ > > include/linux/of_clk.h | 37 ++++++ > > 5 files changed, 282 insertions(+), 0 deletions(-) > > create mode 100644 Documentation/devicetree/bindings/clock/clock-bindings.txt > > create mode 100644 drivers/of/clock.c > > create mode 100644 include/linux/of_clk.h > > > > diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt > > new file mode 100644 > > index 0000000..4770c7e > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt > > @@ -0,0 +1,109 @@ > > +This binding is a work-in-progress, and are based on some experimental > > +work by benh[1]. > > + > > +Sources of clock signal can be represented by any node in the device > > +tree. Those nodes are designated as clock providers. Clock consumer > > +nodes use a phandle and clock specifier pair to connect clock provider > > +outputs to clock inputs. Similar to the gpio specifiers, a clock > > +specifier is an array of one more more cells identifying the clock > > +output on a device. The length of a clock specifier is defined by the > > +value of a #clock-cells property in the clock provider node. > > + > > +[1] http://patchwork.ozlabs.org/patch/31551/ > > + > > +==Clock providers== > > + > > +Required properties: > > +#clock-cells: Number of cells in a clock specifier; typically will be > > + set to 1 > > + > > +Optional properties: > > +clock-output-name: Recommended to be a list of strings of clock output signal > > + names indexed by the first cell in the clock specifier. > > + However, the meaning of clock-output-names is domain > > + specific to the clock provider, and is only provided to > > + encourage using the same meaning for the majority of clock > > + providers. This format may not work for clock providers > > + using a complex clock specifier format. In those cases it > > + is recommended to omit this property and create a binding > > + specific names property. > > + > > + Clock consumer nodes must never directly reference > > + the provider's clock-output-names property. > > + > > +For example: > > + > > + oscillator { > > + #clock-cells = <1>; > > + clock-output-name = "ckil", "ckih"; > > + }; > > + > > +- this node defines a device with two clock outputs, the first named > > + "ckil" and the second named "ckih". Consumer nodes always reference > > + clocks by index. The names should reflect the clock output signal > > + names for the device. > > + > > +==Clock consumers== > > + > > +Required properties: > > +clock-input: List of phandle and clock specifier pairs, one pair > > + for each clock input to the device. > > +clock-input-name: List of clock input name strings sorted in the same > > + order as the clock-input property. Consumers drivers > > + will use clock-input-name to match clock input names > > + with clock-input specifiers. > > + > > +For example: > > + > > + uart { > > + clock-input = <&osc 1> <&ref 0>; > > + clock-input-name = "baud", "register"; > > + }; > > This is duplicated below. > > > + > > + > > +This represents a device with two clock inputs, named "baud" and "register". > > +The baud clock is connected to output 1 of the &osc device, and the register > > +clock is connected to output 0 of the &ref. > > + > > +==Example== > > + > > + /* external oscillator */ > > + osc: oscillator { > > + compatible = "fixed-clock"; > > + #clock-cells = <1>; > > + frequency = <32678>; > > The code is using "clock-frequency" here. > > > + clock-output-name = "osc"; > > + }; > > + > > + /* phase-locked-loop device, generates a higher frequency clock > > + * from the external oscillator reference */ > > + pll: pll { > > + compatible = "some-pll-interface" > > + #clock-cells = <1>; > > + clock-input = <&osc 0>; > > There's a mismatch in #clock-cells size and this. osc #clock-cells is 1. "0" is one cell too. Nothing wrong. Correct my understanding? > > > + clock-input-name = "ref"; > > + reg = <0x4c000 0x1000>; > > + clock-output-name = "pll", "pll-switched"; > > + }; > > + > > + /* UART, using the low frequency oscillator for the baud clock, > > + * and the high frequency switched PLL output for register > > + * clocking */ > > + uart { > > + compatible = "fsl,imx-uart"; > > + reg = <0xa000 0x1000>; > > + interrupts = <33>; > > + clock-input = <&osc 0>, <&pll 1>; > > + clock-input-name = "baud", "register"; > > + }; > > + > > +This DT fragment defines three devices: an external oscillator to provide a > > +low-frequency reference clock, a PLL device to generate a higher frequency > > +clock signal, and a UART. > > + > > +* The oscillator is fixed-frequency, and provides one clock output, named "osc". > > +* The PLL is both a clock provider and a clock consumer. It uses the clock > > + signal generated by the external oscillator, and provides two output signals > > + ("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) > > diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig > > index 268163d..b49ab9c 100644 > > --- a/drivers/of/Kconfig > > +++ b/drivers/of/Kconfig > > @@ -47,6 +47,12 @@ config OF_IRQ > > def_bool y > > depends on !SPARC > > > > +config OF_CLOCK > > + def_bool y > > + depends on HAVE_CLK > > + help > > + OpenFirmware clock accessors > > + > > config OF_DEVICE > > def_bool y > > > > diff --git a/drivers/of/Makefile b/drivers/of/Makefile > > index a73f5a5..e7ad1e9 100644 > > --- a/drivers/of/Makefile > > +++ b/drivers/of/Makefile > > @@ -5,6 +5,7 @@ obj-$(CONFIG_OF_ADDRESS) += address.o > > obj-$(CONFIG_OF_IRQ) += irq.o > > obj-$(CONFIG_OF_DEVICE) += device.o platform.o > > obj-$(CONFIG_OF_GPIO) += gpio.o > > +obj-$(CONFIG_OF_CLOCK) += clock.o > > obj-$(CONFIG_OF_I2C) += of_i2c.o > > obj-$(CONFIG_OF_NET) += of_net.o > > obj-$(CONFIG_OF_SPI) += of_spi.o > > diff --git a/drivers/of/clock.c b/drivers/of/clock.c > > new file mode 100644 > > index 0000000..542b9e4 > > --- /dev/null > > +++ b/drivers/of/clock.c > > @@ -0,0 +1,129 @@ > > +/* > > + * Clock infrastructure for device tree platforms > > + */ > > + > > +#include <linux/clk.h> > > +#include <linux/err.h> > > +#include <linux/errno.h> > > +#include <linux/module.h> > > +#include <linux/of.h> > > +#include <linux/of_clk.h> > > +#include <linux/list.h> > > +#include <linux/mutex.h> > > +#include <linux/slab.h> > > +#include <linux/device.h> > > + > > +/** > > + * struct of_clk_provider - Clock provider registration structure > > + * @link: Entry in global list of clock providers > > + * @node: Pointer to device tree node of clock provider > > + * @get: Get clock callback. Returns NULL or a struct clk for the > > + * given clock specifier > > + * @data: context pointer to be passed into @get callback > > + */ > > +struct of_clk_provider { > > + struct list_head link; > > + > > + struct device_node *node; > > + struct clk *(*get)(struct of_phandle_args *clkspec, void *data); > > + void *data; > > +}; > > + > > +static LIST_HEAD(of_clk_providers); > > +static DEFINE_MUTEX(of_clk_lock); > > + > > +/** > > + * of_clk_add_provider() - Register a clock provider for a node > > + * @np: Device node pointer associated with clock provider > > + * @clk_src_get: callback for decoding clock > > + * @data: context pointer for @clk_src_get callback. > > + */ > > +int of_clk_add_provider(struct device_node *np, > > + struct clk *(*clk_src_get)(struct of_phandle_args *clkspec, > > + void *data), > > + void *data) > > +{ > > + struct of_clk_provider *cp; > > + > > + cp = kzalloc(sizeof(struct of_clk_provider), GFP_KERNEL); > > + if (!cp) > > + return -ENOMEM; > > + > > + cp->node = of_node_get(np); > > + cp->data = data; > > + cp->get = clk_src_get; > > + > > + mutex_lock(&of_clk_lock); > > + list_add(&cp->link, &of_clk_providers); > > + mutex_unlock(&of_clk_lock); > > + pr_debug("Added clock from %s\n", np->full_name); > > + > > + return 0; > > +} > > + > > +/** > > + * of_clk_del_provider() - Remove a previously registered clock provider > > + * @np: Device node pointer associated with clock provider > > + */ > > +void of_clk_del_provider(struct device_node *np) > > +{ > > + struct of_clk_provider *cp; > > + > > + mutex_lock(&of_clk_lock); > > + list_for_each_entry(cp, &of_clk_providers, link) { > > + if (cp->node == np) { > > + list_del(&cp->link); > > + of_node_put(cp->node); > > + kfree(cp); > > + break; > > + } > > + } > > + mutex_unlock(&of_clk_lock); > > +} > > + > > +static struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec) > > +{ > > + struct of_clk_provider *provider; > > + struct clk *clk = NULL; > > + > > + /* Check if we have such a provider in our array */ > > + mutex_lock(&of_clk_lock); > > + list_for_each_entry(provider, &of_clk_providers, link) { > > + if (provider->node == clkspec->np) > > + clk = provider->get(clkspec, provider->data); > > How about: > > if (provider->get) > clk = provider->get(clkspec, provider->data); > else > clk = provider->data; > > > Or a default get function can do this. > > > + if (clk) > > + break; > > + } > > + mutex_unlock(&of_clk_lock); > > + > > + return clk; > > +} > > + > > +struct clk *of_clk_get(struct device_node *np, int index) > > +{ > > + struct of_phandle_args clkspec; > > + struct clk *clk; > > + int rc; > > + > > + if (index < 0) > > + return NULL; > > + > > + rc = of_parse_phandle_with_args(np, "clock", "#clock-cells", index, > > + &clkspec); > > + if (rc) > > + return NULL; > > + > > + clk = __of_clk_get_from_provider(&clkspec); > > + of_node_put(clkspec.np); > > + return clk; > > +} > > + > > +struct clk *of_clk_get_by_name(struct device_node *np, const char *name) > > +{ > > + int index = 0; > > + > > + if (name) > > + index = of_property_match_string(np, "clock-input-names", name); > > + return of_clk_get(np, index); > > +} > > + > > diff --git a/include/linux/of_clk.h b/include/linux/of_clk.h > > new file mode 100644 > > index 0000000..e476a5f > > --- /dev/null > > +++ b/include/linux/of_clk.h > > @@ -0,0 +1,37 @@ > > +/* > > + * Clock infrastructure for device tree platforms > > + */ > > +#ifndef __OF_CLK_H > > +#define __OF_CLK_H > > + > > +struct device; > > +struct clk; > > + > > +#ifdef CONFIG_OF_CLOCK > > + > > +struct device_node; > > + > > +int of_clk_add_provider(struct device_node *np, > > + struct clk *(*clk_src_get)(struct of_phandle_args *args, > > + void *data), > > + void *data); > > + > > +void of_clk_del_provider(struct device_node *np); > > + > > +struct clk *of_clk_get(struct device_node *np, int index); > > +struct clk *of_clk_get_by_name(struct device_node *np, const char *name); > > + > > +#else > > +static struct clk *of_clk_get(struct device_node *np, int index); > > +{ > > + return NULL; > > +} > > + > > +static struct clk *of_clk_get_by_name(struct device_node *np, const char *name) > > +{ > > + return NULL; > > +} > > +#endif > > + > > +#endif /* __OF_CLK_H */ > > + > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
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