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Commit c088c335 authored by Sagar Dharia's avatar Sagar Dharia Committed by Greg Kroah-Hartman
Browse files

slimbus: qcom: Add runtime-pm support using clock-pause 



Slimbus HW mandates that clock-pause sequence has to be executed
before disabling relevant interface and core clocks.
Runtime-PM's autosuspend feature is used here to enter/exit low
power mode for Qualcomm's Slimbus controller. Autosuspend feature
enables driver to avoid changing power-modes too frequently since
entering clock-pause is an expensive sequence

Signed-off-by: default avatarSagar Dharia <sdharia@codeaurora.org>
Signed-off-by: default avatarSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviwed-by: default avatarMark Brown <broonie@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ad7fcbc3

drivers/slimbus/qcom-ctrl.c

+98 −3
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/clk.h>

#include <linux/of.h>

#include <linux/dma-mapping.h>

#include <linux/pm_runtime.h>

#include "slimbus.h"



/* Manager registers */
@@ -65,6 +66,7 @@ 
		((l) | ((mt) << 5) | ((mc) << 8) | ((dt) << 15) | ((ad) << 16))



#define SLIM_ROOT_FREQ 24576000

#define QCOM_SLIM_AUTOSUSPEND 1000



/* MAX message size over control channel */

#define SLIM_MSGQ_BUF_LEN	40
@@ -275,6 +277,30 @@ static irqreturn_t qcom_slim_interrupt(int irq, void *d) 
	return ret;

}



static int qcom_clk_pause_wakeup(struct slim_controller *sctrl)

{

	struct qcom_slim_ctrl *ctrl = dev_get_drvdata(sctrl->dev);



	clk_prepare_enable(ctrl->hclk);

	clk_prepare_enable(ctrl->rclk);

	enable_irq(ctrl->irq);



	writel_relaxed(1, ctrl->base + FRM_WAKEUP);

	/* Make sure framer wakeup write goes through before ISR fires */

	mb();

	/*

	 * HW Workaround: Currently, slave is reporting lost-sync messages

	 * after SLIMbus comes out of clock pause.

	 * Transaction with slave fail before slave reports that message

	 * Give some time for that report to come

	 * SLIMbus wakes up in clock gear 10 at 24.576MHz. With each superframe

	 * being 250 usecs, we wait for 5-10 superframes here to ensure

	 * we get the message

	 */

	usleep_range(1250, 2500);

	return 0;

}



void *slim_alloc_txbuf(struct qcom_slim_ctrl *ctrl, struct slim_msg_txn *txn,

		       struct completion *done)

{
@@ -511,6 +537,7 @@ static int qcom_slim_probe(struct platform_device *pdev) 


	sctrl->set_laddr = qcom_set_laddr;

	sctrl->xfer_msg = qcom_xfer_msg;

	sctrl->wakeup =  qcom_clk_pause_wakeup;

	ctrl->tx.n = QCOM_TX_MSGS;

	ctrl->tx.sl_sz = SLIM_MSGQ_BUF_LEN;

	ctrl->rx.n = QCOM_RX_MSGS;
@@ -618,13 +645,80 @@ static int qcom_slim_remove(struct platform_device *pdev) 
{

	struct qcom_slim_ctrl *ctrl = platform_get_drvdata(pdev);



	pm_runtime_disable(&pdev->dev);

	slim_unregister_controller(&ctrl->ctrl);

	destroy_workqueue(ctrl->rxwq);

	return 0;

}



/*

 * If PM_RUNTIME is not defined, these 2 functions become helper

 * functions to be called from system suspend/resume.

 */

#ifdef CONFIG_PM

static int qcom_slim_runtime_suspend(struct device *device)

{

	struct platform_device *pdev = to_platform_device(device);

	struct qcom_slim_ctrl *ctrl = platform_get_drvdata(pdev);

	int ret;



	dev_dbg(device, "pm_runtime: suspending...\n");

	ret = slim_ctrl_clk_pause(&ctrl->ctrl, false, SLIM_CLK_UNSPECIFIED);

	if (ret) {

		dev_err(device, "clk pause not entered:%d", ret);

	} else {

		disable_irq(ctrl->irq);

		clk_disable_unprepare(ctrl->hclk);

		clk_disable_unprepare(ctrl->rclk);

	slim_unregister_controller(&ctrl->ctrl);

	destroy_workqueue(ctrl->rxwq);

	}

	return ret;

}



static int qcom_slim_runtime_resume(struct device *device)

{

	struct platform_device *pdev = to_platform_device(device);

	struct qcom_slim_ctrl *ctrl = platform_get_drvdata(pdev);

	int ret = 0;



	dev_dbg(device, "pm_runtime: resuming...\n");

	ret = slim_ctrl_clk_pause(&ctrl->ctrl, true, 0);

	if (ret)

		dev_err(device, "clk pause not exited:%d", ret);

	return ret;

}

#endif



#ifdef CONFIG_PM_SLEEP

static int qcom_slim_suspend(struct device *dev)

{

	int ret = 0;



	if (!pm_runtime_enabled(dev) ||

		(!pm_runtime_suspended(dev))) {

		dev_dbg(dev, "system suspend");

		ret = qcom_slim_runtime_suspend(dev);

	}



	return ret;

}



static int qcom_slim_resume(struct device *dev)

{

	if (!pm_runtime_enabled(dev) || !pm_runtime_suspended(dev)) {

		int ret;



		dev_dbg(dev, "system resume");

		ret = qcom_slim_runtime_resume(dev);

		if (!ret) {

			pm_runtime_mark_last_busy(dev);

			pm_request_autosuspend(dev);

		}

		return ret;



	}

	return 0;

}

#endif /* CONFIG_PM_SLEEP */



static const struct dev_pm_ops qcom_slim_dev_pm_ops = {

	SET_SYSTEM_SLEEP_PM_OPS(qcom_slim_suspend, qcom_slim_resume)
@@ -647,6 +741,7 @@ static struct platform_driver qcom_slim_driver = { 
	.driver	= {

		.name = "qcom_slim_ctrl",

		.of_match_table = qcom_slim_dt_match,

		.pm = &qcom_slim_dev_pm_ops,

	},

};

module_platform_driver(qcom_slim_driver);