Currently on OMAP, it is not possible to specify a clock consumer to any of the OMAP generated clocks using the device tree. This can pose a problem for external devices that run off an OMAP clock as we can't reliably provide a reference to the clock in the device tree.
This patch allows device trees to provide a node that contains the clock identifier, clock alias and the device phandle. The board initialization code then creates a clock alias to this clock id, and associates it with the device whose phandle was supplied. Discussion http://www.spinics.net/lists/linux-omap/msg86241.html CC: Russell King <li...@arm.linux.org.uk> CC: Rajendra Nayak <rna...@ti.com> CC: Santosh Shilimkar <santosh.shilim...@ti.com> Signed-off-by: Roger Quadros <rog...@ti.com> --- .../devicetree/bindings/clock/ti-clock-alias.txt | 26 ++++++++ arch/arm/mach-omap2/board-generic.c | 67 ++++++++++++++++++++ 2 files changed, 93 insertions(+), 0 deletions(-) create mode 100644 Documentation/devicetree/bindings/clock/ti-clock-alias.txt diff --git a/Documentation/devicetree/bindings/clock/ti-clock-alias.txt b/Documentation/devicetree/bindings/clock/ti-clock-alias.txt new file mode 100644 index 0000000..87ef4c3 --- /dev/null +++ b/Documentation/devicetree/bindings/clock/ti-clock-alias.txt @@ -0,0 +1,26 @@ +* Clock alias provision for TI OMAP2+ boards + +This binding allows the board's device tree file to specify a clock name, +device phandle and clock alias so that that clock can be associated +to the device with the alias. + +This is required in cases where an external device is clocked by an +OMAP generated clock and needs to be assocated to it. + +NOTE: The node's name should be clock_alias + +Required properties +- clock-name: The clock identifier string. Should be one of the + clock ids defined in OMAP common clock data. +- clock-alias: A string specifying the alias that must be created to the clock. +- device: A phandle to the device this clock should be associated to. + +e.g. On the OMAP4 Panda board, the USB PHY device is clocked by the +FREF_CLK3 (auxclk3_ck) from the OMAP. The PHY driver expexts the clock to +be named "main_clk". This binding can be provided like so + +clock_alias { + clock-name = "auxclk3_ck"; + clock-alias = "main_clk"; + device = <&hsusb1_phy>; +}; diff --git a/arch/arm/mach-omap2/board-generic.c b/arch/arm/mach-omap2/board-generic.c index 0274ff7..2fc48f9 100644 --- a/arch/arm/mach-omap2/board-generic.c +++ b/arch/arm/mach-omap2/board-generic.c @@ -15,6 +15,9 @@ #include <linux/of_irq.h> #include <linux/of_platform.h> #include <linux/irqdomain.h> +#include <linux/clk.h> +#include <linux/string.h> +#include <linux/slab.h> #include <asm/mach/arch.h> @@ -35,12 +38,76 @@ static struct of_device_id omap_dt_match_table[] __initdata = { { } }; +static int __init omap_create_clk_alias(struct device_node *np) +{ + int ret = 0; + const char *s, *alias; + char *clk_id; + struct device_node *dev_np; + struct platform_device *pdev; + + of_property_read_string(np, "clock-name", &s); + if (!s) { + pr_err("%s: couldn't find clock-name property in node %s\n", + __func__, np->name); + return -ENODEV; + } + + clk_id = kstrdup(s, GFP_KERNEL); + if (!clk_id) + return -ENOMEM; + + dev_np = of_parse_phandle(np, "device", 0); + if (!dev_np) { + pr_err("%s: couldn't find device phandle for \'%s\'\n", + __func__, clk_id); + ret = -ENODEV; + goto exit; + } + + pdev = of_find_device_by_node(dev_np); + if (!pdev) { + pr_err("%s: couldn't find device for clock \'%s\'\n", + __func__, clk_id); + ret = -ENODEV; + goto exit; + } + + ret = of_property_read_string(np, "clock-alias", &alias); + if (ret) { + pr_err("%s: couldn't find alias for clock \'%s\'\n", + __func__, clk_id); + ret = -ENODEV; + goto exit; + } + + ret = clk_add_alias(alias, dev_name(&pdev->dev), clk_id, NULL); + if (ret) { + pr_err("%s: couldn't add alias \'%s\' to clock \'%s\'\n", + __func__, alias, clk_id); + ret = -ENODEV; + goto exit; + } + +exit: + kfree(clk_id); + return ret; +} + static void __init omap_generic_init(void) { + struct device_node *np; + omap_sdrc_init(NULL, NULL); of_platform_populate(NULL, omap_dt_match_table, NULL, NULL); + /* create clock aliases based on 'clock_alias' nodes */ + for_each_node_by_name(np, "clock_alias") { + omap_create_clk_alias(np); + of_node_put(np); + } + /* * HACK: call display setup code for selected boards to enable omapdss. * This will be removed when omapdss supports DT. -- 1.7.4.1 _______________________________________________ devicetree-discuss mailing list devicetree-discuss@lists.ozlabs.org https://lists.ozlabs.org/listinfo/devicetree-discuss
