pwm: lpss: Add support for runtime PM

To be able to save some power when PWM is not in use, add support for
runtime PM for this driver. This also allows the platform to transition to
low power S0ix states when the system is idle.

Signed-off-by: Huiquan Zhong <huiquan.zhong@intel.com>
Signed-off-by: Qipeng Zha <qipeng.zha@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/drivers/pwm/pwm-lpss-pci.c b/drivers/pwm/pwm-lpss-pci.c
index c15bc6d00f1a..7160e8ab38a4 100644
--- a/drivers/pwm/pwm-lpss-pci.c
+++ b/drivers/pwm/pwm-lpss-pci.c
@@ -13,6 +13,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/pm_runtime.h>
 
 #include "pwm-lpss.h"
 
@@ -33,6 +34,10 @@ static int pwm_lpss_probe_pci(struct pci_dev *pdev,
 		return PTR_ERR(lpwm);
 
 	pci_set_drvdata(pdev, lpwm);
+
+	pm_runtime_put(&pdev->dev);
+	pm_runtime_allow(&pdev->dev);
+
 	return 0;
 }
 
@@ -40,9 +45,33 @@ static void pwm_lpss_remove_pci(struct pci_dev *pdev)
 {
 	struct pwm_lpss_chip *lpwm = pci_get_drvdata(pdev);
 
+	pm_runtime_forbid(&pdev->dev);
+	pm_runtime_get_sync(&pdev->dev);
+
 	pwm_lpss_remove(lpwm);
 }
 
+#ifdef CONFIG_PM
+static int pwm_lpss_runtime_suspend_pci(struct device *dev)
+{
+	/*
+	 * The PCI core will handle transition to D3 automatically. We only
+	 * need to provide runtime PM hooks for that to happen.
+	 */
+	return 0;
+}
+
+static int pwm_lpss_runtime_resume_pci(struct device *dev)
+{
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops pwm_lpss_pci_pm = {
+	SET_RUNTIME_PM_OPS(pwm_lpss_runtime_suspend_pci,
+			   pwm_lpss_runtime_resume_pci, NULL)
+};
+
 static const struct pci_device_id pwm_lpss_pci_ids[] = {
 	{ PCI_VDEVICE(INTEL, 0x0ac8), (unsigned long)&pwm_lpss_bxt_info},
 	{ PCI_VDEVICE(INTEL, 0x0f08), (unsigned long)&pwm_lpss_byt_info},
@@ -60,6 +89,9 @@ static struct pci_driver pwm_lpss_driver_pci = {
 	.id_table = pwm_lpss_pci_ids,
 	.probe = pwm_lpss_probe_pci,
 	.remove = pwm_lpss_remove_pci,
+	.driver = {
+		.pm = &pwm_lpss_pci_pm,
+	},
 };
 module_pci_driver(pwm_lpss_driver_pci);