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Subject[PATCH v9 12/13] slimbus: qcom: Add runtime-pm support using clock-pause
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/qcom-ctrl.c | 101 ++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 98 insertions(+), 3 deletions(-)

diff --git a/drivers/slimbus/qcom-ctrl.c b/drivers/slimbus/qcom-ctrl.c
index 36e828b703b4..2c9a275d8d9e 100644
--- a/drivers/slimbus/qcom-ctrl.c
+++ b/drivers/slimbus/qcom-ctrl.c
@@ -12,6 +12,7 @@
#include <linux/clk.h>
#include <linux/of.h>
#include <linux/dma-mapping.h>
+#include <linux/pm_runtime.h>
#include "slimbus.h"

/* Manager registers */
@@ -63,6 +64,7 @@
((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
@@ -273,6 +275,30 @@ 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)
{
@@ -509,6 +535,7 @@ 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;
@@ -616,14 +643,81 @@ static int qcom_slim_remove(struct platform_device *pdev)
{
struct qcom_slim_ctrl *ctrl = platform_get_drvdata(pdev);

- disable_irq(ctrl->irq);
- clk_disable_unprepare(ctrl->hclk);
- clk_disable_unprepare(ctrl->rclk);
+ 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);
+ }
+ 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)
SET_RUNTIME_PM_OPS(
@@ -645,6 +739,7 @@ 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);
--
2.15.0
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