powerpc/powernv: Add support for direct mapped LPC on POWER9

Use the new non-PCI ISA bridge support to expose the POWER9
LPC bus as direct mapped via the ISA IO port range. This
enables direct access via drivers such as 8250

Signed-off-by: Benjamin Herrenschmidt <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>

Author: ozbenh

arch/powerpc/kernel/legacy_serial.c

@@ -233,7 +233,8 @@ static int __init add_legacy_isa_port(struct device_node *np,
 	 *
 	 * Note: Don't even try on P8 lpc, we know it's not directly mapped
 	 */
-	if (!of_device_is_compatible(isa_brg, "ibm,power8-lpc")) {
+	if (!of_device_is_compatible(isa_brg, "ibm,power8-lpc") ||
+	    of_get_property(isa_brg, "ranges", NULL)) {
 		taddr = of_translate_address(np, reg);
 		if (taddr == OF_BAD_ADDR)
 			taddr = 0;

arch/powerpc/platforms/powernv/opal-lpc.c

@@ -407,9 +407,17 @@ void opal_lpc_init(void)
 	if (opal_lpc_chip_id < 0)
 		return;
 
-	/* Setup special IO ops */
-	ppc_pci_io = opal_lpc_io;
-	isa_io_special = true;
-
-	pr_info("OPAL: Power8 LPC bus found, chip ID %d\n", opal_lpc_chip_id);
+	/* Does it support direct mapping ? */
+	if (of_get_property(np, "ranges", NULL)) {
+		pr_info("OPAL: Found memory mapped LPC bus on chip %d\n",
+			opal_lpc_chip_id);
+		isa_bridge_init_non_pci(np);
+	} else {
+		pr_info("OPAL: Found non-mapped LPC bus on chip %d\n",
+			opal_lpc_chip_id);
+
+		/* Setup special IO ops */
+		ppc_pci_io = opal_lpc_io;
+		isa_io_special = true;
+	}
 }