* [PATCH 01/10] metag: init common clk and use "core" clk
[not found] ` <1371125981-5184-1-git-send-email-james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
@ 2013-06-13 12:19 ` James Hogan
0 siblings, 0 replies; 2+ messages in thread
From: James Hogan @ 2013-06-13 12:19 UTC (permalink / raw)
To: linux-kernel-u79uwXL29TY76Z2rM5mHXA
Cc: Grant Likely, devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ,
James Hogan, Mike Turquette, Rob Herring
If the common clock framework is enabled, call of_clk_init(NULL) in
time_init() to register device tree clocks with the clock framework.
After this time_init() calls a new function init_metag_clocks(), which
looks for a clock named "core" in the node compatible with "img,meta"
(usually the root node). If found the get_core_freq machine callback is
overridden to obtain the core clock frequency using that clock.
Signed-off-by: James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
Cc: Mike Turquette <mturquette-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
---
Documentation/devicetree/bindings/metag/meta.txt | 30 +++++++++++++
arch/metag/include/asm/clock.h | 8 ++++
arch/metag/kernel/clock.c | 57 +++++++++++++++++++++++-
arch/metag/kernel/time.c | 14 +++++-
4 files changed, 106 insertions(+), 3 deletions(-)
create mode 100644 Documentation/devicetree/bindings/metag/meta.txt
diff --git a/Documentation/devicetree/bindings/metag/meta.txt b/Documentation/devicetree/bindings/metag/meta.txt
new file mode 100644
index 0000000..f4457f5
--- /dev/null
+++ b/Documentation/devicetree/bindings/metag/meta.txt
@@ -0,0 +1,30 @@
+* Meta Processor Binding
+
+This binding specifies what properties must be available in the device tree
+representation of a Meta Processor Core, which is the root node in the tree.
+
+Required properties:
+
+ - compatible: Specifies the compatibility list for the Meta processor.
+ The type shall be <string> and the value shall include "img,meta".
+
+Optional properties:
+
+ - clocks: Clock consumer specifiers as described in
+ Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+ - clock-names: Clock consumer names as described in
+ Documentation/devicetree/bindings/clock/clock-bindings.txt.
+
+Clocks are identified by name. Valid clocks are:
+
+ - "core": The Meta core clock from which the Meta timers are derived.
+
+* Examples
+
+/ {
+ compatible = "toumaz,tz1090", "img,meta";
+
+ clocks = <&meta_core_clk>;
+ clock-names = "core";
+};
diff --git a/arch/metag/include/asm/clock.h b/arch/metag/include/asm/clock.h
index 3e2915a..ded4ab2 100644
--- a/arch/metag/include/asm/clock.h
+++ b/arch/metag/include/asm/clock.h
@@ -19,6 +19,8 @@
* core frequency will be determined like this:
* Meta 1: based on loops_per_jiffy.
* Meta 2: (EXPAND_TIMER_DIV + 1) MHz.
+ * If a "core" clock is provided by the device tree, it
+ * will override this function.
*/
struct meta_clock_desc {
unsigned long (*get_core_freq)(void);
@@ -27,6 +29,12 @@ struct meta_clock_desc {
extern struct meta_clock_desc _meta_clock;
/*
+ * Perform platform clock initialisation, reading clocks from device tree etc.
+ * Only accessible during boot.
+ */
+void init_metag_clocks(void);
+
+/*
* Set up the default clock, ensuring all callbacks are valid - only accessible
* during boot.
*/
diff --git a/arch/metag/kernel/clock.c b/arch/metag/kernel/clock.c
index defc840..8bfd6a5 100644
--- a/arch/metag/kernel/clock.c
+++ b/arch/metag/kernel/clock.c
@@ -8,8 +8,10 @@
* published by the Free Software Foundation.
*/
+#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/io.h>
+#include <linux/of.h>
#include <asm/param.h>
#include <asm/clock.h>
@@ -34,8 +36,61 @@ static unsigned long get_core_freq_default(void)
#endif
}
+static struct clk *clk_core;
+
+/* Clk based get_core_freq callback. */
+static unsigned long get_core_freq_clk(void)
+{
+ return clk_get_rate(clk_core);
+}
+
+/**
+ * init_metag_core_clock() - Set up core clock from devicetree.
+ *
+ * Checks to see if a "core" clock is provided in the device tree, and overrides
+ * the get_core_freq callback to use it.
+ */
+static void __init init_metag_core_clock(void)
+{
+ /*
+ * See if a core clock is provided by the devicetree (and
+ * registered by the init callback above).
+ */
+ struct device_node *node;
+ node = of_find_compatible_node(NULL, NULL, "img,meta");
+ if (!node) {
+ pr_warn("%s: no compatible img,meta DT node found\n",
+ __func__);
+ return;
+ }
+
+ clk_core = of_clk_get_by_name(node, "core");
+ if (IS_ERR(clk_core)) {
+ pr_warn("%s: no core clock found in DT\n",
+ __func__);
+ return;
+ }
+
+ /*
+ * Override the core frequency callback to use
+ * this clk.
+ */
+ _meta_clock.get_core_freq = get_core_freq_clk;
+}
+
+/**
+ * init_metag_clocks() - Set up clocks from devicetree.
+ *
+ * Set up important clocks from device tree. In particular any needed for clock
+ * sources.
+ */
+void __init init_metag_clocks(void)
+{
+ init_metag_core_clock();
+}
+
/**
- * setup_meta_clocks() - Set up the Meta clock.
+ * setup_meta_clocks() - Early set up of the Meta clock.
* @desc: Clock descriptor usually provided by machine description
*
* Ensures all callbacks are valid.
diff --git a/arch/metag/kernel/time.c b/arch/metag/kernel/time.c
index 17dc107..f1c8c53 100644
--- a/arch/metag/kernel/time.c
+++ b/arch/metag/kernel/time.c
@@ -5,11 +5,21 @@
*
*/
-#include <linux/init.h>
-
#include <clocksource/metag_generic.h>
+#include <linux/clk-provider.h>
+#include <linux/init.h>
+#include <asm/clock.h>
void __init time_init(void)
{
+#ifdef CONFIG_COMMON_CLK
+ /* Init clocks from device tree */
+ of_clk_init(NULL);
+#endif
+
+ /* Init meta clocks, particularly the core clock */
+ init_metag_clocks();
+
+ /* Set up the timer clock sources */
metag_generic_timer_init();
}
--
1.8.1.2
^ permalink raw reply related [flat|nested] 2+ messages in thread