[PATCH v3] 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. 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 at linux.intel.com>
Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
Tested-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner at br-automation.com>
Tested-by: Wolfgang Wallner <wolfgang.wallner at br-automation.com>

---

Changes in v3:
- extract the base address assignment to a helper

Changes in v2:
- not to break Fixes, etc to two or more lines in the commit message
- add the same CONFIG_SYS_NS16550_PORT_MAPPED ifdefs in the PCI case

 drivers/serial/ns16550.c | 39 ++++++++++++++++++++++-----------------
 1 file 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);
-- 
2.7.4