[PATCH v4 4/5] HID: intel-thc-hid: intel-ipts: handle system sleep

[Emfox Zhou <emfox@debian.org>]

System sleep takes the port down and builds it up again rather than
keeping the HID device across it: the controller forgets the streaming
mode user space asked it for, and hidraw offers no way to tell user
space to ask again. The device goes away and comes back, so the daemon
watching it restarts and repeats the request.

Signed-off-by: Emfox Zhou <emfox@debian.org>
---
 .../hid/intel-thc-hid/intel-ipts/pci-ipts.c   | 36 +++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/hid/intel-thc-hid/intel-ipts/pci-ipts.c b/drivers/hid/intel-thc-hid/intel-ipts/pci-ipts.c
index 8f8db21d..81a46149 100644
--- a/drivers/hid/intel-thc-hid/intel-ipts/pci-ipts.c
+++ b/drivers/hid/intel-thc-hid/intel-ipts/pci-ipts.c
@@ -142,6 +142,41 @@ static void thc_ipts_remove(struct pci_dev *pci)
 	pci_clear_master(pci);
 }
 
+/*
+ * The controller forgets the streaming mode and hidraw cannot ask user space
+ * to repeat itself, so the port is taken down and rebuilt: the HID device
+ * comes back and the daemon restarts with it.
+ */
+static int thc_ipts_suspend(struct device *dev)
+{
+	struct thc_ipts *idev = dev_get_drvdata(dev);
+
+	if (!idev)
+		return -ENODEV;
+
+	thc_ipts_port_stop(idev);
+
+	return 0;
+}
+
+static int thc_ipts_resume(struct device *dev)
+{
+	struct thc_ipts *idev = dev_get_drvdata(dev);
+	int ret;
+
+	if (!idev)
+		return -ENODEV;
+
+	ret = thc_ipts_port_start(idev);
+	if (ret)
+		thc_ipts_port_stop(idev);
+
+	return ret;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(thc_ipts_pm_ops, thc_ipts_suspend,
+				thc_ipts_resume);
+
 static void thc_ipts_shutdown(struct pci_dev *pci)
 {
 	struct thc_ipts *idev = pci_get_drvdata(pci);
@@ -156,6 +191,7 @@ static struct pci_driver thc_ipts_driver = {
 	.probe		= thc_ipts_probe,
 	.remove		= thc_ipts_remove,
 	.shutdown	= thc_ipts_shutdown,
+	.driver.pm	= pm_ptr(&thc_ipts_pm_ops),
 	/* Bring-up waits for the controller, up to a few seconds. */
 	.driver.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 };