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 af7b109e3d28..8c05346cd69c 100644 --- a/drivers/slimbus/qcom-ctrl.c +++ b/drivers/slimbus/qcom-ctrl.c @@ -20,6 +20,7 @@ #include <linux/clk.h> #include <linux/of.h> #include <linux/dma-mapping.h> +#include <linux/pm_runtime.h> #include "slimbus.h"
/* Manager registers */ @@ -71,6 +72,7 @@ ((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 @@ -281,6 +283,30 @@ 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) { @@ -517,6 +543,7 @@ 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; @@ -624,14 +651,81 @@ 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( @@ -653,6 +747,7 @@ 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);