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Subject[Patch v6 5/7] slimbus: qcom: Add runtime-pm support using clock-pause feature
Date
From: Sagar Dharia <sdharia@codeaurora.org>

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: Sagar Dharia <sdharia@codeaurora.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
---
drivers/slimbus/slim-qcom-ctrl.c | 128 +++++++++++++++++++++++++++++++++++++--
drivers/slimbus/slim-qcom.h | 1 +
2 files changed, 125 insertions(+), 4 deletions(-)

diff --git a/drivers/slimbus/slim-qcom-ctrl.c b/drivers/slimbus/slim-qcom-ctrl.c
index d0574e1..05ba44f 100644
--- a/drivers/slimbus/slim-qcom-ctrl.c
+++ b/drivers/slimbus/slim-qcom-ctrl.c
@@ -21,6 +21,7 @@
#include <linux/of.h>
#include <linux/dma-mapping.h>
#include <linux/slimbus.h>
+#include <linux/pm_runtime.h>
#include "slim-qcom.h"

#define MSM_SLIM_NAME "msm_slim_ctrl"
@@ -217,6 +218,30 @@ static irqreturn_t msm_slim_interrupt(int irq, void *d)
return ret;
}

+static int msm_clk_pause_wakeup(struct slim_controller *ctrl)
+{
+ struct msm_slim_ctrl *dev = slim_get_ctrldata(ctrl);
+
+ clk_prepare_enable(dev->hclk);
+ clk_prepare_enable(dev->rclk);
+ enable_irq(dev->irq);
+
+ writel_relaxed(1, dev->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;
+}
+
static int msm_xfer_msg(struct slim_controller *ctrl, struct slim_msg_txn *txn,
void *pbuf)
{
@@ -286,7 +311,6 @@ static int msm_set_laddr(struct slim_controller *ctrl,
*/
msg.wbuf = buf;
msg.num_bytes = 7;
-
ret = slim_processtxn(&dev->ctrl, &txn);

if (ret)
@@ -417,6 +441,8 @@ static int msm_slim_probe(struct platform_device *pdev)

dev->ctrl.set_laddr = msm_set_laddr;
dev->ctrl.xfer_msg = msm_xfer_msg;
+ dev->ctrl.wakeup = msm_clk_pause_wakeup;
+
dev->ctrl.tx.n = MSM_TX_MSGS;
dev->ctrl.rx.n = MSM_RX_MSGS;
dev->ctrl.tx.sl_sz = SLIM_MSGQ_BUF_LEN;
@@ -532,6 +558,12 @@ static int msm_slim_probe(struct platform_device *pdev)
*/
mb();

+ pm_runtime_use_autosuspend(&pdev->dev);
+ pm_runtime_set_autosuspend_delay(&pdev->dev, MSM_SLIM_AUTOSUSPEND);
+ pm_runtime_set_active(&pdev->dev);
+ pm_runtime_mark_last_busy(&pdev->dev);
+ pm_runtime_enable(&pdev->dev);
+
dev_dbg(dev->dev, "MSM SB controller is up:ver:0x%x!\n", dev->ver);
return 0;

@@ -562,14 +594,101 @@ static int msm_slim_remove(struct platform_device *pdev)
dma_free_coherent(&pdev->dev, (ctrl->tx.sl_sz * ctrl->tx.n),
ctrl->tx.base, ctrl->tx.phy);

- disable_irq(dev->irq);
- clk_disable_unprepare(dev->rclk);
- clk_disable_unprepare(dev->hclk);
+ pm_runtime_disable(&pdev->dev);
slim_del_controller(&dev->ctrl);
destroy_workqueue(dev->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 msm_slim_runtime_suspend(struct device *device)
+{
+ struct platform_device *pdev = to_platform_device(device);
+ struct msm_slim_ctrl *dev = platform_get_drvdata(pdev);
+ int ret;
+
+ dev_dbg(device, "pm_runtime: suspending...\n");
+ ret = slim_ctrl_clk_pause(&dev->ctrl, false, SLIM_CLK_UNSPECIFIED);
+ if (ret) {
+ dev_err(device, "clk pause not entered:%d", ret);
+ } else {
+ disable_irq(dev->irq);
+ clk_disable_unprepare(dev->hclk);
+ clk_disable_unprepare(dev->rclk);
+ }
+ return ret;
+}
+
+static int msm_slim_runtime_resume(struct device *device)
+{
+ struct platform_device *pdev = to_platform_device(device);
+ struct msm_slim_ctrl *dev = platform_get_drvdata(pdev);
+ int ret = 0;
+
+ dev_dbg(device, "pm_runtime: resuming...\n");
+ ret = slim_ctrl_clk_pause(&dev->ctrl, true, 0);
+ if (ret)
+ dev_err(device, "clk pause not exited:%d", ret);
+ return ret;
+}
+#endif
+
+#ifdef CONFIG_PM_SLEEP
+static int msm_slim_suspend(struct device *dev)
+{
+ int ret = 0;
+
+ if (!pm_runtime_enabled(dev) ||
+ (!pm_runtime_suspended(dev))) {
+ dev_dbg(dev, "system suspend");
+ ret = msm_slim_runtime_suspend(dev);
+ }
+ if (ret == -EISCONN) {
+ /**
+ * If the clock pause failed due to active channels, there is
+ * a possibility that some audio stream is active during suspend.
+ * (e.g. modem usecase during suspend)
+ * We dont want to return suspend failure in that case so that
+ * display and relevant components can still go to suspend.
+ * If there is some other error, then it should prevent
+ * system level suspend
+ */
+ ret = 0;
+ }
+ return ret;
+}
+
+static int msm_slim_resume(struct device *dev)
+{
+ if (!pm_runtime_enabled(dev) || !pm_runtime_suspended(dev)) {
+ int ret;
+
+ dev_dbg(dev, "system resume");
+ ret = msm_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 msm_slim_dev_pm_ops = {
+ SET_SYSTEM_SLEEP_PM_OPS(msm_slim_suspend, msm_slim_resume)
+ SET_RUNTIME_PM_OPS(
+ msm_slim_runtime_suspend,
+ msm_slim_runtime_resume,
+ NULL
+ )
+};
+
static const struct of_device_id msm_slim_dt_match[] = {
{
.compatible = "qcom,slim",
@@ -584,6 +703,7 @@ static struct platform_driver msm_slim_driver = {
.name = MSM_SLIM_NAME,
.owner = THIS_MODULE,
.of_match_table = msm_slim_dt_match,
+ .pm = &msm_slim_dev_pm_ops,
},
};
module_platform_driver(msm_slim_driver);
diff --git a/drivers/slimbus/slim-qcom.h b/drivers/slimbus/slim-qcom.h
index 0ad59c3..8b1d649 100644
--- a/drivers/slimbus/slim-qcom.h
+++ b/drivers/slimbus/slim-qcom.h
@@ -23,6 +23,7 @@
((l) | ((mt) << 5) | ((mc) << 8) | ((dt) << 15) | ((ad) << 16))

#define SLIM_ROOT_FREQ 24576000
+#define MSM_SLIM_AUTOSUSPEND 1000

/* MAX message size over control channel */
#define SLIM_MSGQ_BUF_LEN 40
--
2.9.3
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