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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: Sagar Dharia <sdharia@codeaurora.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviwed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sagar Dharia 2017-12-11 23:43:06 +00:00 committed by Greg Kroah-Hartman
parent ad7fcbc308
commit c088c335b4
1 changed files with 98 additions and 3 deletions
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101
drivers/slimbus/qcom-ctrl.c
View File

@ -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;
@ -618,14 +645,81 @@ 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(
@ -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);