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Subject[PATCH RESEND] CLK: ARC: Set initial pll output frequency specified in device tree
Date
Add option to set initial output frequency of plls via
"clock-frequency" property in pll's device tree node.
This frequency will be set while pll driver probed.

The usage example is setting CPU clock frequency on boot
See discussion:
https://www.mail-archive.com/linux-snps-arc@lists.infradead.org/msg02689.html

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
---
.../bindings/clock/snps,hsdk-pll-clock.txt | 5 ++++
.../devicetree/bindings/clock/snps,pll-clock.txt | 5 ++++
drivers/clk/axs10x/pll_clock.c | 34 ++++++++++++++++++++--
drivers/clk/clk-hsdk-pll.c | 34 ++++++++++++++++++++--
4 files changed, 74 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/clock/snps,hsdk-pll-clock.txt b/Documentation/devicetree/bindings/clock/snps,hsdk-pll-clock.txt
index c56c755..5703059 100644
--- a/Documentation/devicetree/bindings/clock/snps,hsdk-pll-clock.txt
+++ b/Documentation/devicetree/bindings/clock/snps,hsdk-pll-clock.txt
@@ -13,6 +13,10 @@ Required properties:
- clocks: shall be the input parent clock phandle for the PLL.
- #clock-cells: from common clock binding; Should always be set to 0.

+Optional properties:
+- clock-frequency: output frequency generated by pll in Hz which will be set
+while probing. Should be a single cell.
+
Example:
input_clk: input-clk {
clock-frequency = <33333333>;
@@ -25,4 +29,5 @@ Example:
reg = <0x00 0x10>;
#clock-cells = <0>;
clocks = <&input_clk>;
+ clock-frequency = <1000000000>;
};
diff --git a/Documentation/devicetree/bindings/clock/snps,pll-clock.txt b/Documentation/devicetree/bindings/clock/snps,pll-clock.txt
index 11fe487..5908f99 100644
--- a/Documentation/devicetree/bindings/clock/snps,pll-clock.txt
+++ b/Documentation/devicetree/bindings/clock/snps,pll-clock.txt
@@ -13,6 +13,10 @@ registers and second for corresponding LOCK CGU register.
- clocks: shall be the input parent clock phandle for the PLL.
- #clock-cells: from common clock binding; Should always be set to 0.

+Optional properties:
+- clock-frequency: output frequency generated by pll in Hz which will be set
+while probing. Should be a single cell.
+
Example:
input-clk: input-clk {
clock-frequency = <33333333>;
@@ -25,4 +29,5 @@ Example:
reg = <0x80 0x10>, <0x100 0x10>;
#clock-cells = <0>;
clocks = <&input-clk>;
+ clock-frequency = <100000000>;
};
diff --git a/drivers/clk/axs10x/pll_clock.c b/drivers/clk/axs10x/pll_clock.c
index 25d8c24..3f4345d 100644
--- a/drivers/clk/axs10x/pll_clock.c
+++ b/drivers/clk/axs10x/pll_clock.c
@@ -11,6 +11,7 @@
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/clk-provider.h>
+#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/device.h>
@@ -215,6 +216,25 @@ static const struct clk_ops axs10x_pll_ops = {
.set_rate = axs10x_pll_set_rate,
};

+static void set_pll_rate_from_of(struct clk *clk, struct device_node *node)
+{
+ u32 requested_rate;
+
+ /* If we specify initial pll output frequency try to set it */
+ if (of_property_read_u32(node, "clock-frequency", &requested_rate))
+ return;
+
+ if (clk_prepare_enable(clk)) {
+ pr_err("Cannot enable %s clock.\n", node->name);
+ return;
+ }
+
+ if (clk_set_rate(clk, requested_rate))
+ pr_err("Cannot set %s clock rate.\n", node->name);
+
+ pr_debug("Set %s clock to %u\n", node->name, requested_rate);
+}
+
static int axs10x_pll_clk_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
@@ -258,8 +278,15 @@ static int axs10x_pll_clk_probe(struct platform_device *pdev)
return ret;
}

- return of_clk_add_hw_provider(dev->of_node, of_clk_hw_simple_get,
- &pll_clk->hw);
+ ret = of_clk_add_hw_provider(dev->of_node, of_clk_hw_simple_get,
+ &pll_clk->hw);
+ if (ret)
+ return ret;
+
+ /* If we specify initial pll output frequency in dts try to set it */
+ set_pll_rate_from_of(pll_clk->hw.clk, dev->of_node);
+
+ return 0;
}

static int axs10x_pll_clk_remove(struct platform_device *pdev)
@@ -311,6 +338,9 @@ static void __init of_axs10x_pll_clk_setup(struct device_node *node)
goto err_unregister_clk;
}

+ /* If we specify initial pll output frequency in dts try to set it */
+ set_pll_rate_from_of(pll_clk->hw.clk, node);
+
return;

err_unregister_clk:
diff --git a/drivers/clk/clk-hsdk-pll.c b/drivers/clk/clk-hsdk-pll.c
index bbf23717..74fd006 100644
--- a/drivers/clk/clk-hsdk-pll.c
+++ b/drivers/clk/clk-hsdk-pll.c
@@ -9,6 +9,7 @@
*/

#include <linux/clk-provider.h>
+#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
@@ -295,6 +296,25 @@ static const struct clk_ops hsdk_pll_ops = {
.set_rate = hsdk_pll_set_rate,
};

+static void set_pll_rate_from_of(struct clk *clk, struct device_node *node)
+{
+ u32 requested_rate;
+
+ /* If we specify initial pll output frequency try to set it */
+ if (of_property_read_u32(node, "clock-frequency", &requested_rate))
+ return;
+
+ if (clk_prepare_enable(clk)) {
+ pr_err("Cannot enable %s clock.\n", node->name);
+ return;
+ }
+
+ if (clk_set_rate(clk, requested_rate))
+ pr_err("Cannot set %s clock rate.\n", node->name);
+
+ pr_debug("Set %s clock to %u\n", node->name, requested_rate);
+}
+
static int hsdk_pll_clk_probe(struct platform_device *pdev)
{
int ret;
@@ -340,8 +360,15 @@ static int hsdk_pll_clk_probe(struct platform_device *pdev)
return ret;
}

- return of_clk_add_hw_provider(dev->of_node, of_clk_hw_simple_get,
- &pll_clk->hw);
+ ret = of_clk_add_hw_provider(dev->of_node, of_clk_hw_simple_get,
+ &pll_clk->hw);
+ if (ret)
+ return ret;
+
+ /* If we specify initial pll output frequency in dts try to set it */
+ set_pll_rate_from_of(pll_clk->hw.clk, dev->of_node);
+
+ return 0;
}

static int hsdk_pll_clk_remove(struct platform_device *pdev)
@@ -400,6 +427,9 @@ static void __init of_hsdk_pll_clk_setup(struct device_node *node)
goto err_unmap_spec_regs;
}

+ /* If we specify initial pll output frequency in dts try to set it */
+ set_pll_rate_from_of(pll_clk->hw.clk, node);
+
return;

err_unmap_spec_regs:
--
2.9.3
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