From 843107498f91e57d1d4b22cd8787112726fdaeb4 Mon Sep 17 00:00:00 2001
From: Samuel Holland <samuel@sholland.org>
Date: Sun, 3 Jan 2021 05:06:34 -0600
Subject: [PATCH] bus: sunxi-rsb: Implement suspend/resume/shutdown callbacks

Since system firmware is likely to use the RSB bus to communicate with a
PMIC while the system is suspended, we cannot make any assumptions about
the controller state after resuming. Thus it is important to completely
reinitialize the controller.

The RSB bus needs to be ready as soon as IRQs are enabled, to handle
wakeup event IRQs coming from the PMIC. Thus it uses NOIRQ callbacks.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
 drivers/bus/sunxi-rsb.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
index 3f290da45619..efd222f36cdc 100644
--- a/drivers/bus/sunxi-rsb.c
+++ b/drivers/bus/sunxi-rsb.c
@@ -45,6 +45,7 @@
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
+#include <linux/pm.h>
 #include <linux/regmap.h>
 #include <linux/reset.h>
 #include <linux/slab.h>
@@ -675,6 +676,22 @@ static void sunxi_rsb_hw_exit(struct sunxi_rsb *rsb)
 	clk_disable_unprepare(rsb->clk);
 }
 
+static int __maybe_unused sunxi_rsb_suspend(struct device *dev)
+{
+	struct sunxi_rsb *rsb = dev_get_drvdata(dev);
+
+	sunxi_rsb_hw_exit(rsb);
+
+	return 0;
+}
+
+static int __maybe_unused sunxi_rsb_resume(struct device *dev)
+{
+	struct sunxi_rsb *rsb = dev_get_drvdata(dev);
+
+	return sunxi_rsb_hw_init(rsb);
+}
+
 static int sunxi_rsb_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -756,6 +773,17 @@ static int sunxi_rsb_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static void sunxi_rsb_shutdown(struct platform_device *pdev)
+{
+	struct sunxi_rsb *rsb = platform_get_drvdata(pdev);
+
+	sunxi_rsb_hw_exit(rsb);
+}
+
+static const struct dev_pm_ops sunxi_rsb_dev_pm_ops = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(sunxi_rsb_suspend, sunxi_rsb_resume)
+};
+
 static const struct of_device_id sunxi_rsb_of_match_table[] = {
 	{ .compatible = "allwinner,sun8i-a23-rsb" },
 	{}
@@ -765,9 +793,11 @@ MODULE_DEVICE_TABLE(of, sunxi_rsb_of_match_table);
 static struct platform_driver sunxi_rsb_driver = {
 	.probe = sunxi_rsb_probe,
 	.remove	= sunxi_rsb_remove,
+	.shutdown = sunxi_rsb_shutdown,
 	.driver	= {
 		.name = RSB_CTRL_NAME,
 		.of_match_table = sunxi_rsb_of_match_table,
+		.pm = &sunxi_rsb_dev_pm_ops,
 	},
 };