[PATCH] serial: ns16550: Fix ordering of getting base address

[Bin Meng]

Currently the driver gets ns16550 base address in the driver
probe() routine, which may potentially break any ns16550 wrapper
driver that does additional initialization before calling
ns16550_serial_probe().

Things are complicated that we need consider ns16550 devices on
both simple-bus and PCI bus. To fix the issue we move the base
address assignment for simple-bus ns16550 device back to the
ofdata_to_platdata(), and assign base address for PCI ns16550
device in ns16550_serial_probe().

This is still not perfect. Ideally if any PCI bus based ns16550
wrapper driver tries to access plat->base before calling probe(),
it is subject to break.

Fixes: 720f9e1fdb0c9 ("serial: ns16550: Move PCI access from
ofdata_to_platdata() to probe()")
Reported-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
Signed-off-by: Bin Meng <bmeng.cn at gmail.com>

---

 drivers/serial/ns16550.c | 51 +++++++++++++++++++++++-------------------------
 1 file changed, 24 insertions(+), 27 deletions(-)

diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
index c1b303f..5e3cd1c 100644
--- a/drivers/serial/ns16550.c
+++ b/drivers/serial/ns16550.c
@@ -479,39 +479,24 @@ static int ns16550_serial_getinfo(struct udevice *dev,
 	return 0;
 }
 
-#if CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)
-static int ns1655_serial_set_base_addr(struct udevice *dev)
-{
-	fdt_addr_t addr;
-	struct ns16550_platdata *plat;
-
-	plat = dev_get_platdata(dev);
-
-	addr = dev_read_addr_pci(dev);
-	if (addr == FDT_ADDR_T_NONE)
-		return -EINVAL;
-
-#ifdef CONFIG_SYS_NS16550_PORT_MAPPED
-	plat->base = addr;
-#else
-	plat->base = (unsigned long)map_physmem(addr, 0, MAP_NOCACHE);
-#endif
-
-	return 0;
-}
-#endif
-
 int ns16550_serial_probe(struct udevice *dev)
 {
+	struct ns16550_platdata *plat = dev->platdata;
 	struct NS16550 *const com_port = dev_get_priv(dev);
 	struct reset_ctl_bulk reset_bulk;
+	fdt_addr_t addr;
 	int ret;
 
-#if CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)
-	ret = ns1655_serial_set_base_addr(dev);
-	if (ret)
-		return ret;
-#endif
+	/*
+	 * If we are on PCI bus, either directly attached to a PCI root port,
+	 * or via a PCI bridge, assign platdata->base before probing hardware.
+	 */
+	if (device_is_on_pci_bus(dev)) {
+		addr = devfdt_get_addr_pci(dev);
+		if (addr == FDT_ADDR_T_NONE)
+			return -EINVAL;
+		plat->base = addr;
+	}
 
 	ret = reset_get_bulk(dev, &reset_bulk);
 	if (!ret)
@@ -535,9 +520,21 @@ int ns16550_serial_ofdata_to_platdata(struct udevice *dev)
 {
 	struct ns16550_platdata *plat = dev->platdata;
 	const u32 port_type = dev_get_driver_data(dev);
+	fdt_addr_t addr;
 	struct clk clk;
 	int err;
 
+	addr = dev_read_addr(dev);
+	if (addr != FDT_ADDR_T_NONE) {
+#ifdef CONFIG_SYS_NS16550_PORT_MAPPED
+		plat->base = addr;
+#else
+		plat->base = (unsigned long)map_physmem(addr, 0, MAP_NOCACHE);
+#endif
+	} else if (!device_is_on_pci_bus(dev)) {
+		return -EINVAL;
+	}
+
 	plat->reg_offset = dev_read_u32_default(dev, "reg-offset", 0);
 	plat->reg_shift = dev_read_u32_default(dev, "reg-shift", 0);
 	plat->reg_width = dev_read_u32_default(dev, "reg-io-width", 1);
-- 
2.7.4