serial: ns16550: Fix ordering of getting base address

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. If any PCI bus based ns16550 wrapper
driver tries to access plat->base before calling probe(), it is
still subject to break.

Fixes: 720f9e1fdb0c9 ("serial: ns16550: Move PCI access from ofdata_to_platdata() to probe()")
Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Tested-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>

1 files changed, 22 insertions, 17 deletions

diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
index c1b303f..a2f1b35 100644
--- a/drivers/serial/ns16550.c
+++ b/drivers/serial/ns16550.c
@@ -479,39 +479,38 @@ 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)
+static int ns16550_serial_assign_base(struct ns16550_platdata *plat, ulong base)
 {
-	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)
+	if (base == FDT_ADDR_T_NONE)
 		return -EINVAL;
 
 #ifdef CONFIG_SYS_NS16550_PORT_MAPPED
-	plat->base = addr;
+	plat->base = base;
 #else
-	plat->base = (unsigned long)map_physmem(addr, 0, MAP_NOCACHE);
+	plat->base = (unsigned long)map_physmem(base, 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);
+		ret = ns16550_serial_assign_base(plat, addr);
+		if (ret)
+			return ret;
+	}
 
 	ret = reset_get_bulk(dev, &reset_bulk);
 	if (!ret)
@@ -535,9 +534,15 @@ 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);
+	err = ns16550_serial_assign_base(plat, addr);
+	if (err && !device_is_on_pci_bus(dev))
+		return err;
+
 	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);