[PATCH V5 1/6] clk: OMAP: introduce device tree binding to kernel clock data

Based on discussion contributions from Roger Quadros, Grygorii Strashko
and others.

Cc: Kevin Hilman <redacted>
Cc: Mike Turquette <redacted>
Cc: Paul Walmsley <paul@pwsan.com>
[tony at atomide.com: co-developed]
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
---
Changes in this version:
        - review comments incorporated.
Previous version of this patch was discussed in:
        http://marc.info/?t=136580758500001&r=1&w=2

 .../devicetree/bindings/clock/omap-clock.txt       |   40 +++++++++
 drivers/clk/Makefile                               |    1 +
 drivers/clk/omap/Makefile                          |    1 +
 drivers/clk/omap/clk.c                             |   91 ++++++++++++++++++++
 4 files changed, 133 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/omap-clock.txt
 create mode 100644 drivers/clk/omap/Makefile
 create mode 100644 drivers/clk/omap/clk.c

diff --git a/Documentation/devicetree/bindings/clock/omap-clock.txt b/Documentation/devicetree/bindings/clock/omap-clock.txt
new file mode 100644
index 0000000..047c1e7
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/omap-clock.txt

@@ -0,0 +1,40 @@
+Device Tree Clock bindings for Texas Instrument's OMAP compatible platforms
+
+This binding is an initial minimal binding that may be enhanced as part of
+transitioning OMAP clock data out of kernel image.
+
+This binding uses the common clock binding[1].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible : shall be "ti,omap-clock"
+- #clock-cells : from common clock binding; shall be set to 0.
+NOTE:
+node name should map to clock database in arch/arm/mach-omap2/cclock<SoC>_data.c
+Since all clocks are described with _ck, the node name is optimized to drop the
+usage of _ck. For example, a clock called dpll1_ck will be defined as dpll1.
+
+Example #1: describing clock node for CPU on OMAP34xx platform:
+Ref: arch/arm/mach-omap2/cclock3xxx_data.c
+describes the CPU clock to be as follows
+       CLK(NULL,       "dpll1_ck",     &dpll1_ck,      CK_3XXX),
+Corresponding binding will be:
+       dpll1: dpll1 {
+               #clock-cells = <0>;
+               compatible = "ti,omap-clock";
+       };
+And it's usage will be:
+               clocks = <&dpll1>;
+
+Example #2: describing clock node for auxilary clock #3 on OMAP443x platform:
+Ref: arch/arm/mach-omap2/cclock44xx_data.c
+describes the auxclk3 clock to be as follows:
+       CLK(NULL,       "auxclk3_ck",   &auxclk3_ck,    CK_443X),
+Corresponding binding will be:
+       auxclk3: auxclk3 {
+               #clock-cells = <0>;
+               compatible = "ti,omap-clock";
+       };
+And it's usage will be:
+       clocks = <&auxclk3>;

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 137d3e7..1d5a2ec 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile

@@ -30,6 +30,7 @@ obj-$(CONFIG_ARCH_VT8500)     += clk-vt8500.o
 obj-$(CONFIG_ARCH_ZYNQ)                += clk-zynq.o
 obj-$(CONFIG_ARCH_TEGRA)       += tegra/
 obj-$(CONFIG_PLAT_SAMSUNG)     += samsung/
+obj-$(CONFIG_ARCH_OMAP)                += omap/
 
 obj-$(CONFIG_X86)              += x86/
 

diff --git a/drivers/clk/omap/Makefile b/drivers/clk/omap/Makefile
new file mode 100644
index 0000000..8195931
--- /dev/null
+++ b/drivers/clk/omap/Makefile

@@ -0,0 +1 @@
+obj-y                                  += clk.o

diff --git a/drivers/clk/omap/clk.c b/drivers/clk/omap/clk.c
new file mode 100644
index 0000000..5a3c6d9
--- /dev/null
+++ b/drivers/clk/omap/clk.c

@@ -0,0 +1,91 @@
+/*
+ * Texas Instruments OMAP Clock driver
+ *
+ * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com/
+ *     Nishanth Menon <nm@ti.com>
+ *     Tony Lindgren <tony@atomide.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.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/string.h>
+
+static const struct of_device_id omap_clk_of_match[] = {
+       {.compatible = "ti,omap-clock",},
+       {},
+};
+
+/**
+ * omap_clk_src_get() - Get OMAP clock from node name when needed
+ * @clkspec:   clkspec argument
+ * @data:      unused
+ *
+ * REVISIT: We assume the following:
+ * 1. omap clock names end with _ck
+ * 2. omap clock names are under 32 characters in length
+ */
+static struct clk *omap_clk_src_get(struct of_phandle_args *clkspec, void *data)
+{
+       struct clk *clk;
+       char clk_name[32];
+       struct device_node *np = clkspec->np;
+
+       snprintf(clk_name, 32, "%s_ck", np->name);
+       clk = clk_get(NULL, clk_name);
+       if (IS_ERR(clk))
+               pr_err("%s: could not get clock %s(%ld)\n", __func__,
+                      clk_name, PTR_ERR(clk));
+
+       return clk;
+}
+
+/**
+ * omap_clk_probe() - create link from DT definition to clock data
+ * @pdev:      device node
+ *
+ * NOTE: we look up the clock lazily when the consumer driver does
+ * of_clk_get() and initialize a NULL clock here.
+ */
+static int omap_clk_probe(struct platform_device *pdev)
+{
+       int res;
+       struct device_node *np = pdev->dev.of_node;
+
+       /* This allows the driver to of_clk_get() */
+       res = of_clk_add_provider(np, omap_clk_src_get, NULL);
+       if (res)
+               dev_err(&pdev->dev, "could not add provider(%d)\n", res);
+
+       return res;
+}
+
+static struct platform_driver omap_clk_driver = {
+       .probe = omap_clk_probe,
+       .driver = {
+                  .name = "omap_clk",
+                  .of_match_table = of_match_ptr(omap_clk_of_match),
+                  },
+};
+
+static int __init omap_clk_init(void)
+{
+       return platform_driver_register(&omap_clk_driver);
+}
+arch_initcall(omap_clk_init);
+
+MODULE_DESCRIPTION("OMAP Clock driver");
+MODULE_AUTHOR("Texas Instruments Inc.");
+MODULE_LICENSE("GPL v2");

-- 
1.7.9.5