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>

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"
 
@@ -33,16 +34,44 @@ 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;
 }
 
 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);
 

drivers/pwm/pwm-lpss-platform.c

@@ -14,6 +14,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 
 #include "pwm-lpss.h"
 
@@ -36,13 +37,18 @@ static int pwm_lpss_probe_platform(struct platform_device *pdev)
 		return PTR_ERR(lpwm);
 
 	platform_set_drvdata(pdev, lpwm);
+
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
 	return 0;
 }
 
 static int pwm_lpss_remove_platform(struct platform_device *pdev)
 {
 	struct pwm_lpss_chip *lpwm = platform_get_drvdata(pdev);
 
+	pm_runtime_disable(&pdev->dev);
 	return pwm_lpss_remove(lpwm);
 }
 

drivers/pwm/pwm-lpss.c

@@ -16,6 +16,7 @@
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/pm_runtime.h>
 
 #include "pwm-lpss.h"
 
@@ -105,6 +106,8 @@ static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
 		duty_ns = 1;
 	on_time_div = 255 - (255 * duty_ns / period_ns);
 
+	pm_runtime_get_sync(chip->dev);
+
 	ctrl = pwm_lpss_read(pwm);
 	ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
 	ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT;
@@ -113,18 +116,22 @@ static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	ctrl |= PWM_SW_UPDATE;
 	pwm_lpss_write(pwm, ctrl);
 
+	pm_runtime_put(chip->dev);
+
 	return 0;
 }
 
 static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
+	pm_runtime_get_sync(chip->dev);
 	pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_ENABLE);
 	return 0;
 }
 
 static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE);
+	pm_runtime_put(chip->dev);
 }
 
 static const struct pwm_ops pwm_lpss_ops = {