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Subject[PATCH 4/4] bus: sunxi-rsb: Implement runtime power management
Date
Gate the clock to save power while the controller is idle.

Signed-off-by: Samuel Holland <samuel@sholland.org>
---
drivers/bus/sunxi-rsb.c | 44 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)

diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
index efd222f36cdc..ba5100dfc413 100644
--- a/drivers/bus/sunxi-rsb.c
+++ b/drivers/bus/sunxi-rsb.c
@@ -46,6 +46,7 @@
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
+#include <linux/pm_runtime.h>
#include <linux/regmap.h>
#include <linux/reset.h>
#include <linux/slab.h>
@@ -337,6 +338,10 @@ static int sunxi_rsb_read(struct sunxi_rsb *rsb, u8 rtaddr, u8 addr,
return -EINVAL;
}

+ ret = pm_runtime_resume_and_get(rsb->dev);
+ if (ret)
+ return ret;
+
mutex_lock(&rsb->lock);

writel(addr, rsb->regs + RSB_ADDR);
@@ -352,6 +357,9 @@ static int sunxi_rsb_read(struct sunxi_rsb *rsb, u8 rtaddr, u8 addr,
unlock:
mutex_unlock(&rsb->lock);

+ pm_runtime_mark_last_busy(rsb->dev);
+ pm_runtime_put_autosuspend(rsb->dev);
+
return ret;
}

@@ -379,6 +387,10 @@ static int sunxi_rsb_write(struct sunxi_rsb *rsb, u8 rtaddr, u8 addr,
return -EINVAL;
}

+ ret = pm_runtime_resume_and_get(rsb->dev);
+ if (ret)
+ return ret;
+
mutex_lock(&rsb->lock);

writel(addr, rsb->regs + RSB_ADDR);
@@ -389,6 +401,9 @@ static int sunxi_rsb_write(struct sunxi_rsb *rsb, u8 rtaddr, u8 addr,

mutex_unlock(&rsb->lock);

+ pm_runtime_mark_last_busy(rsb->dev);
+ pm_runtime_put_autosuspend(rsb->dev);
+
return ret;
}

@@ -672,10 +687,29 @@ static int sunxi_rsb_hw_init(struct sunxi_rsb *rsb)

static void sunxi_rsb_hw_exit(struct sunxi_rsb *rsb)
{
+ /* Keep the clock and PM reference counts consistent. */
+ if (pm_runtime_status_suspended(rsb->dev))
+ pm_runtime_resume(rsb->dev);
reset_control_assert(rsb->rstc);
clk_disable_unprepare(rsb->clk);
}

+static int __maybe_unused sunxi_rsb_runtime_suspend(struct device *dev)
+{
+ struct sunxi_rsb *rsb = dev_get_drvdata(dev);
+
+ clk_disable_unprepare(rsb->clk);
+
+ return 0;
+}
+
+static int __maybe_unused sunxi_rsb_runtime_resume(struct device *dev)
+{
+ struct sunxi_rsb *rsb = dev_get_drvdata(dev);
+
+ return clk_prepare_enable(rsb->clk);
+}
+
static int __maybe_unused sunxi_rsb_suspend(struct device *dev)
{
struct sunxi_rsb *rsb = dev_get_drvdata(dev);
@@ -758,6 +792,12 @@ static int sunxi_rsb_probe(struct platform_device *pdev)
if (ret)
dev_warn(dev, "Initialize device mode failed: %d\n", ret);

+ pm_suspend_ignore_children(dev, true);
+ pm_runtime_set_active(dev);
+ pm_runtime_set_autosuspend_delay(dev, MSEC_PER_SEC);
+ pm_runtime_use_autosuspend(dev);
+ pm_runtime_enable(dev);
+
of_rsb_register_devices(rsb);

return 0;
@@ -768,6 +808,7 @@ static int sunxi_rsb_remove(struct platform_device *pdev)
struct sunxi_rsb *rsb = platform_get_drvdata(pdev);

device_for_each_child(rsb->dev, NULL, sunxi_rsb_remove_devices);
+ pm_runtime_disable(&pdev->dev);
sunxi_rsb_hw_exit(rsb);

return 0;
@@ -777,10 +818,13 @@ static void sunxi_rsb_shutdown(struct platform_device *pdev)
{
struct sunxi_rsb *rsb = platform_get_drvdata(pdev);

+ pm_runtime_disable(&pdev->dev);
sunxi_rsb_hw_exit(rsb);
}

static const struct dev_pm_ops sunxi_rsb_dev_pm_ops = {
+ SET_RUNTIME_PM_OPS(sunxi_rsb_runtime_suspend,
+ sunxi_rsb_runtime_resume, NULL)
SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(sunxi_rsb_suspend, sunxi_rsb_resume)
};

--
2.26.2
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