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mfd: qcom_rpm: Handle message RAM clock

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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: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
Linus Walleij 2016-08-18 20:40:45 +02:00 committed by Lee Jones
parent 8c5d057159
commit 3526403353
1 changed files with 20 additions and 0 deletions
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20
drivers/mfd/qcom_rpm.c
View File

@ -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;
}