usb: musb: omap2+: save and restore OTG_INTERFSEL

we need to save and restore OTG_INTERFSEL register
else we will be unable to function on resume after
OFF mode.
Reported-by: Devaraj Rangasamy <dev@ti.com>
Signed-off-by: Hema HK <hemahk@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Vikram Pandita <vikram.pandita@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/musb/musb_core.h

@@ -311,6 +311,7 @@ struct musb_context_registers {
 	u8 index, testmode;
 
 	u8 devctl, busctl, misc;
+	u32 otg_interfsel;
 
 	struct musb_csr_regs index_regs[MUSB_C_NUM_EPS];
 };

drivers/usb/musb/omap2430.c

@@ -491,6 +491,9 @@ static int omap2430_runtime_suspend(struct device *dev)
 	struct omap2430_glue		*glue = dev_get_drvdata(dev);
 	struct musb			*musb = glue_to_musb(glue);
 
+	musb->context.otg_interfsel = musb_readl(musb->mregs,
+						OTG_INTERFSEL);
+
 	omap2430_low_level_exit(musb);
 	otg_set_suspend(musb->xceiv, 1);
 
@@ -503,6 +506,9 @@ static int omap2430_runtime_resume(struct device *dev)
 	struct musb			*musb = glue_to_musb(glue);
 
 	omap2430_low_level_init(musb);
+	musb_writel(musb->mregs, OTG_INTERFSEL,
+					musb->context.otg_interfsel);
+
 	otg_set_suspend(musb->xceiv, 0);
 
 	return 0;