[PATCH v3] serial: ns16550: Fix ordering of getting base address

[Andy Shevchenko]

On Fri, Apr 03, 2020 at 06:35:32PM -0700, Bin Meng wrote:
> 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>

And re-tested. Works for me, thanks!

> 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
> 

-- 
With Best Regards,
Andy Shevchenko