This patch adds support for using clock gates (clk-gate) from DT based
on Rob Herrings DT clk binding support for 3.6.
It adds a helper function to clk-gate to allocate all resources required by
a set of individual clock gates, i.e. register base address and lock. Each
clock gate is described as a child of the clock-gating-control in DT and
also created by the helper function.
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxxxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
Cc: Rob Herring <rob.herring@xxxxxxxxxxx>
Cc: Rob Landley <rob@xxxxxxxxxxx>
Cc: Mike Turquette <mturquette@xxxxxx>
Cc: devicetree-discuss@xxxxxxxxxxxxxxxx
Cc: linux-doc@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
---
.../bindings/clock/clock-gating-control.txt | 80 +++++++++++++++++++
drivers/clk/clk-gate.c | 84 ++++++++++++++++++++
include/linux/clk-provider.h | 2 +
3 files changed, 166 insertions(+)
create mode 100644 Documentation/devicetree/bindings/clock/clock-gating-control.txt
diff --git a/Documentation/devicetree/bindings/clock/clock-gating-control.txt b/Documentation/devicetree/bindings/clock/clock-gating-control.txt
new file mode 100644
index 0000000..05f5728
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/clock-gating-control.txt
@@ -0,0 +1,80 @@
+Binding for simple clock gating control based on clock gate register with one
+bit per clock gate. This is a clock consumer and also a clock provider for a
+set of gated clocks that are described as children of this node. Each clock gate
+is described by a bit number and polarity to control the gate.
+
+This binding uses the common clock binding[1].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+==Clock gating control==
+
+Required properties:
+- compatible : shall be "clock-gating-control".
+- reg : should contain the register physical address and length for
+ the clock gating control.
+- clocks : shared parent clock for all gated clocks.
+- #clock-cells : from common clock binding; shall be set to 0.
+- #address-cells : number of cells required to describe a clock gate;
+ should be <2>.
+- #size-cells : should be zero.
+
+Each individual clock gate bit is described as a child of the
+corresponding gating control register with the following properties.
+
+Required child properties:
+- reg : should contain the individual bit and polarity to control
+ the clock gate. A polarity of 0 means that by setting the
+ bit to 1 the clock passes through the clock gate while
+ setting the bit to 0 disables the clock. Any other value
+ for polarity inverts the meaning of the control bit.
+
+Optional child properties:
+- clocks : overrides the shared parent clock for this clock gate
+ by the clock passed in this property.
+- clock-output-names : from common clock binding; allows to set
+ a specific name for the gated clock output.
+
+==Example==
+
+ /* fixed root clock */
+ osc: oscillator {
+ compatible = "fixed-clock";
+ #clock-cells = <0>;
+ clock-frequency = <166666667>;
+ };
+
+ /* sata peripheral clock */
+ sata_clk: ext-oscillator {
+ compatible = "fixed-clock";
+ #clock-cells = <0>;
+ clock-frequency = <25000000>;
+ };
+
+ /* register-based clock gating control */
+ gating-control@f10d0038 {
+ compatible = "clock-gating-control";
+ reg = <0xf10d0038 0x4>;
+ clocks = <&osc>;
+ #clock-cells = <0>;
+ #address-cells = <2>;
+ #size-cells = <0>;
+
+ /* USB0 clock gate on register bit 0 with inverted polarity */
+ cg_usb0: clockgate@0 {
+ reg = <0 1>; /* register bit 0, inverted polarity */
+ };
+
+ /* PCIe0 clock gate on register bit 1 with normal polarity
+ * and named output clock */
+ cg_pcie0: clockgate@1 {
+ reg = <1 0>; /* register bit 1, normal polarity */
+ clock-output-names = "pcie0_clk";
+ };
+
+ /* SATA clock gate with different parent clock */
+ cg_sata: clockgate@3 {
+ reg = <3 0>; /* register bit 3, normal polarity */
+ clocks = <&sata_clk>;
+ };
+ };
diff --git a/drivers/clk/clk-gate.c b/drivers/clk/clk-gate.c
index 578465e..1e88907 100644
--- a/drivers/clk/clk-gate.c
+++ b/drivers/clk/clk-gate.c
@@ -15,6 +15,9 @@
#include <linux/io.h>
#include <linux/err.h>
#include <linux/string.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
/**
* DOC: basic gatable clock which can gate and ungate it's ouput
@@ -148,3 +151,84 @@ struct clk *clk_register_gate(struct device *dev, const char *name,
return clk;
}
+
+#ifdef CONFIG_OF
+/**
+ * of_clock_gating_control_setup() - Setup function for clock gate control
+ * This is a helper for using clk-gate from OF device tree. It allocates
+ * a common lock for a base register and creates the individual clk-gates.
+ */
+void __init of_clock_gating_control_setup(struct device_node *np)
+{
+ struct device_node *child;
+ const char *pclk_name;
+ void __iomem *base;
+ spinlock_t *lockp;
+ unsigned int rnum;
+ u64 addr;
+
+ pclk_name = of_clk_get_parent_name(np, 0);
+ if (!pclk_name) {
+ pr_debug("%s: unable to get parent clock for %s\n",
+ __func__, np->full_name);
+ return;
+ }
+
+ lockp = kzalloc(sizeof(spinlock_t), GFP_KERNEL);
+ if (!lockp) {
+ pr_debug("%s: unable to allocate spinlock for %s\n",
+ __func__, np->full_name);
+ return;
+ }
+
+ spin_lock_init(lockp);
+ base = of_iomap(np, 0);
+ rnum = sizeof(resource_size_t) * 8;
+ addr = of_translate_address(np, of_get_property(np, "reg", NULL));
+
+ pr_debug("create clock gate control %s\n", np->full_name);
+
+ for_each_child_of_node(np, child) {
+ struct clk *cg;
+ const char *cg_name;
+ const char *cg_pclk_name;
+ u32 propval[2];
+ unsigned int rbit;
+
+ if (of_property_read_u32_array(child, "reg", propval, 2)) {
+ pr_debug("%s: wrong #reg on %s\n",
+ __func__, child->full_name);
+ continue;
+ }
+
+ rbit = propval[0];
+ if (rbit >= rnum) {
+ pr_debug("%s: bit position of %s exceeds resources\n",
+ __func__, child->full_name);
+ continue;
+ }
+
+ cg_pclk_name = of_clk_get_parent_name(child, 0);
+ if (!pclk_name)
+ cg_pclk_name = pclk_name;
+
+ if (of_property_read_string(child, "clock-output-names",
+ &cg_name)) {
+ unsigned int nlen = 4 + 16 + strlen(child->name);
+ char *name = kzalloc(nlen+1, GFP_KERNEL);
+ if (!name)
+ continue;
+ snprintf(name, nlen, "%u@%llx.%s", rbit,
+ (unsigned long long)addr, child->name);
+ cg_name = name;
+ }
+
+ pr_debug(" create clock gate: %s\n", cg_name);
+
+ cg = clk_register_gate(NULL, cg_name, cg_pclk_name, 0,
+ base, rbit, propval[1], lockp);
+ if (cg)
+ of_clk_add_provider(child, of_clk_src_simple_get, cg);
+ }
+}
+#endif
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index b97f61e..499eac2 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -205,6 +205,8 @@ struct clk *clk_register_gate(struct device *dev, const char *name,
void __iomem *reg, u8 bit_idx,
u8 clk_gate_flags, spinlock_t *lock);
+void of_clock_gating_control_setup(struct device_node *np);
+
/**
* struct clk_divider - adjustable divider clock
*
--
1.7.10
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