[PATCH v1 1/5] drm: bridge: dw_hdmi: cec: Add cec suspend/resume function

[Sandor . yu]

From: Sandor Yu <Sandor.yu@xxxxxxx>

CEC interrupt status/mask and logical address registers
will be reset when device enter suspend.
It will cause cec fail to work after device resume.
Add CEC suspend/resume functions, save these registers status
when suspend and restore them when resume.

Signed-off-by: Sandor Yu <Sandor.yu@xxxxxxx>
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c | 35 +++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c
index c8f44bcb298a..ceb619b32fde 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c
@@ -18,6 +18,8 @@
 
 #include "dw-hdmi-cec.h"
 
+static u8 cec_saved_regs[5];
+
 enum {
 	HDMI_IH_CEC_STAT0	= 0x0106,
 	HDMI_IH_MUTE_CEC_STAT0	= 0x0186,
@@ -306,11 +308,44 @@ static int dw_hdmi_cec_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static int __maybe_unused dw_hdmi_cec_resume(struct device *dev)
+{
+	struct dw_hdmi_cec *cec = dev_get_drvdata(dev);
+
+	/* Restore logical address and interrupt status/mask register */
+	dw_hdmi_write(cec, cec_saved_regs[0], HDMI_CEC_ADDR_L);
+	dw_hdmi_write(cec, cec_saved_regs[1], HDMI_CEC_ADDR_H);
+	dw_hdmi_write(cec, cec_saved_regs[2], HDMI_CEC_POLARITY);
+	dw_hdmi_write(cec, cec_saved_regs[3], HDMI_CEC_MASK);
+	dw_hdmi_write(cec, cec_saved_regs[4], HDMI_IH_MUTE_CEC_STAT0);
+
+	return 0;
+}
+
+static int __maybe_unused dw_hdmi_cec_suspend(struct device *dev)
+{
+	struct dw_hdmi_cec *cec = dev_get_drvdata(dev);
+
+	/* store logical address and interrupt status/mask register */
+	cec_saved_regs[0] = dw_hdmi_read(cec, HDMI_CEC_ADDR_L);
+	cec_saved_regs[1] = dw_hdmi_read(cec, HDMI_CEC_ADDR_H);
+	cec_saved_regs[2] = dw_hdmi_read(cec, HDMI_CEC_POLARITY);
+	cec_saved_regs[3] = dw_hdmi_read(cec, HDMI_CEC_MASK);
+	cec_saved_regs[4] = dw_hdmi_read(cec, HDMI_IH_MUTE_CEC_STAT0);
+
+	return 0;
+}
+
+static const struct dev_pm_ops dw_hdmi_cec_pm = {
+	SET_SYSTEM_SLEEP_PM_OPS(dw_hdmi_cec_suspend, dw_hdmi_cec_resume)
+};
+
 static struct platform_driver dw_hdmi_cec_driver = {
 	.probe	= dw_hdmi_cec_probe,
 	.remove	= dw_hdmi_cec_remove,
 	.driver = {
 		.name = "dw-hdmi-cec",
+		.pm = &dw_hdmi_cec_pm,
 	},
 };
 module_platform_driver(dw_hdmi_cec_driver);
-- 
2.25.1