From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: Re: [RFC 6/8] of: add clock providers Date: Tue, 08 Nov 2011 20:49:42 -0600 Message-ID: <4EB9EA46.3030300@gmail.com> References: <1320801583-12774-1-git-send-email-grant.likely@secretlab.ca> <1320801583-12774-7-git-send-email-grant.likely@secretlab.ca> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1320801583-12774-7-git-send-email-grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: Grant Likely Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, Sascha Hauer , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org 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 > --- > .../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. > + 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 > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +/** > + * 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 */ > +