i3c: master: svc: fix i3c suspend/resume issue

When system suspends, if i3c module is powered down, register
value will lose.
Need to save the key registers before system suspend.
So save these registers value in runtime pm suspend, and restore them
if these register's value is different with the saved values
when runtime pm resume.

Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20230517033030.3068085-1-xiaoning.wang@nxp.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: wangxiaoningnxp

drivers/i3c/master/svc-i3c-master.c

@@ -145,6 +145,11 @@ struct svc_i3c_xfer {
 	struct svc_i3c_cmd cmds[];
 };
 
+struct svc_i3c_regs_save {
+	u32 mconfig;
+	u32 mdynaddr;
+};
+
 /**
  * struct svc_i3c_master - Silvaco I3C Master structure
  * @base: I3C master controller
@@ -173,6 +178,7 @@ struct svc_i3c_master {
 	struct i3c_master_controller base;
 	struct device *dev;
 	void __iomem *regs;
+	struct svc_i3c_regs_save saved_regs;
 	u32 free_slots;
 	u8 addrs[SVC_I3C_MAX_DEVS];
 	struct i3c_dev_desc *descs[SVC_I3C_MAX_DEVS];
@@ -1579,10 +1585,28 @@ static void svc_i3c_master_remove(struct platform_device *pdev)
 	pm_runtime_disable(&pdev->dev);
 }
 
+static void svc_i3c_save_regs(struct svc_i3c_master *master)
+{
+	master->saved_regs.mconfig = readl(master->regs + SVC_I3C_MCONFIG);
+	master->saved_regs.mdynaddr = readl(master->regs + SVC_I3C_MDYNADDR);
+}
+
+static void svc_i3c_restore_regs(struct svc_i3c_master *master)
+{
+	if (readl(master->regs + SVC_I3C_MDYNADDR) !=
+	    master->saved_regs.mdynaddr) {
+		writel(master->saved_regs.mconfig,
+		       master->regs + SVC_I3C_MCONFIG);
+		writel(master->saved_regs.mdynaddr,
+		       master->regs + SVC_I3C_MDYNADDR);
+	}
+}
+
 static int __maybe_unused svc_i3c_runtime_suspend(struct device *dev)
 {
 	struct svc_i3c_master *master = dev_get_drvdata(dev);
 
+	svc_i3c_save_regs(master);
 	svc_i3c_master_unprepare_clks(master);
 	pinctrl_pm_select_sleep_state(dev);
 
@@ -1596,6 +1620,8 @@ static int __maybe_unused svc_i3c_runtime_resume(struct device *dev)
 	pinctrl_pm_select_default_state(dev);
 	svc_i3c_master_prepare_clks(master);
 
+	svc_i3c_restore_regs(master);
+
 	return 0;
 }