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Commit 35264033 authored by Linus Walleij's avatar Linus Walleij Committed by Lee Jones
Browse files

mfd: qcom_rpm: Handle message RAM clock 



The MSM8660, APQ8060, IPQ806x and MSM8960 have a GCC clock
to the message RAM used by the RPM. This needs to be enabled
for messages to pass through. This is a crude solution that
simply prepare/enable at probe() and disable/unprepare
at remove(). More elaborate PM is probably possible to
add later.

The construction uses IS_ERR() to gracefully handle the
platforms that do not provide a message RAM clock. It will
bail out of probe only if the clock is hitting a probe
deferral situation.

Of course this requires the proper device tree set-up:

rpm: rpm@104000 {
    compatible = "qcom,rpm-msm8660";
    clocks = <&gcc RPM_MSG_RAM_H_CLK>;
    clock-names = "ram";
    ...
};

I have provided this in the MSM8660 device tree, and will
provide patches for the other targets.

Cc: Björn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
parent 8c5d0571

drivers/mfd/qcom_rpm.c

+20 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <linux/mfd/qcom_rpm.h>

#include <linux/mfd/syscon.h>

#include <linux/regmap.h>

#include <linux/clk.h>



#include <dt-bindings/mfd/qcom-rpm.h>
@@ -48,6 +49,7 @@ struct qcom_rpm { 
	struct regmap *ipc_regmap;

	unsigned ipc_offset;

	unsigned ipc_bit;

	struct clk *ramclk;



	struct completion ack;

	struct mutex lock;
@@ -552,6 +554,20 @@ static int qcom_rpm_probe(struct platform_device *pdev) 
	mutex_init(&rpm->lock);

	init_completion(&rpm->ack);



	/* Enable message RAM clock */

	rpm->ramclk = devm_clk_get(&pdev->dev, "ram");

	if (IS_ERR(rpm->ramclk)) {

		ret = PTR_ERR(rpm->ramclk);

		if (ret == -EPROBE_DEFER)

			return ret;

		/*

		 * Fall through in all other cases, as the clock is

		 * optional. (Does not exist on all platforms.)

		 */

		rpm->ramclk = NULL;

	}

	clk_prepare_enable(rpm->ramclk); /* Accepts NULL */



	irq_ack = platform_get_irq_byname(pdev, "ack");

	if (irq_ack < 0) {

		dev_err(&pdev->dev, "required ack interrupt missing\n");
@@ -672,7 +688,11 @@ static int qcom_rpm_probe(struct platform_device *pdev) 


static int qcom_rpm_remove(struct platform_device *pdev)

{

	struct qcom_rpm *rpm = dev_get_drvdata(&pdev->dev);



	of_platform_depopulate(&pdev->dev);

	clk_disable_unprepare(rpm->ramclk);



	return 0;

}