serial: core: make serial_base_bus_type const

Now that the driver core can properly handle constant struct bus_type,
move the serial_base_bus_type variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: "Ricardo B. Marliere" <ricardo@marliere.net>
Link: https://lore.kernel.org/r/20240203-bus_cleanup-tty-v1-2-86b698c82efe@marliere.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: core: Fix serial core port id, including multiport devices

We want to fix the serial core port DEVNAME to use a port id of the
hardware specific controller port instance instead of the port->line.

For example, the 8250 driver sets up a number of serial8250 ports
initially that can be inherited by the hardware specific driver. At that
the port->line no longer decribes the port's relation to the serial core
controller instance.

Let's fix the issue by assigning port->port_id for each serial core
controller port instance.

Fixes: 7d695d83767c ("serial: core: Fix serial_base_match() after fixing controller port name")
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230811103648.2826-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: core: Revert port_id use

Guenter reports boot issues with duplicate sysfs entries for multiport
drivers. Let's go back to using port->line for now to fix the regression.

With this change, the serial core port device names are not correct for the
hardware specific 8250 single port drivers, but that's a cosmetic issue for
now.

Fixes: d962de6ae51f ("serial: core: Fix serial core port id to not use port->line")
Reported-by: Guenter Roeck <groeck7@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230806062052.47737-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: core: Fix kmemleak issue for serial core device remove

Kmemleak reports issues for serial8250 ports after the hardware specific
driver takes over on boot as noted by Tomi.

The kerneldoc for device_initialize() says we must call device_put()
after calling device_initialize(). We are calling device_put() on the
error path, but are missing it from the device remove path. This causes
release() to never get called for the devices on remove.

Let's add the missing put_device() calls for both serial ctrl and
port devices.

Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM")
Reported-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Tested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://lore.kernel.org/r/20230804090909.51529-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: core: Fix serial_base_match() after fixing controller port name

While fixing DEVNAME to be more usable, I broke serial_base_match() as the
ctrl and port prefix for device names seemed unnecessary.

The prefixes are still needed by serial_base_match() to probe the serial
base controller port, and serial tx is now broken.

Let's fix the issue by checking against dev->type and drv->name instead
of the prefixes that are no longer in the DEVNAME.

Fixes: 1ef2c2df1199 ("serial: core: Fix serial core controller port name to show controller id")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202308021529.35b3ad6c-oliver.sang@intel.com
Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230803071034.25571-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: core: Fix serial core controller port name to show controller id

We are missing the serial core controller id for the serial core port
name. Let's fix the issue for sane sysfs output, and to avoid issues
addressing serial ports later on.

And as we're now showing the controller id, the "ctrl" and "port" prefix
for the DEVNAME become useless, we can just drop them. Let's standardize on
DEVNAME:0 for controller name, where 0 is the controller id. And
DEVNAME:0.0 for port name, where 0.0 are the controller id and port id.

This makes the sysfs output nicer, on qemu for example:

$ ls /sys/bus/serial-base/devices
00:04:0 serial8250:0 serial8250:0.2
00:04:0.0 serial8250:0.1 serial8250:0.3

Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM")
Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230725054216.45696-4-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: core: Fix serial core port id to not use port->line

The serial core port id should be serial core controller specific port
instance, which is not always the port->line index.

For example, 8250 driver maps a number of legacy ports, and when a
hardware specific device driver takes over, we typically have one
driver instance for each port. Let's instead add port->port_id to
keep track serial ports mapped to each serial core controller instance.

Currently this is only a cosmetic issue for the serial core port device
names. The issue can be noticed looking at /sys/bus/serial-base/devices
for example though. Let's fix the issue to avoid port addressing issues
later on.

Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM")
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20230725054216.45696-3-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: core: fix -EPROBE_DEFER handling in init

The -EPROBE_DEFER error path in serial_base_device_init() is a bit
awkward. Before the call to device_initialize(dev) then we need to
manually release all the device resources. And after the call then we
need to call put_device() to release the resources. Doing either one
wrong will result in a leak or a use after free.

So let's wait to return -EPROBE_DEFER until after the call to
device_initialize(dev) so that way callers do not have to handle
-EPROBE_DEFER as a special case. Now callers can just use put_device()
for clean up.

The second issue with the -EPROBE_DEFER path is that deferring is not
supposed to be a fatal error, but instead it's normal part of the
init process and the kernel recovers from it automatically. That means
we should not print an error message but just a debug message on this
path.

Fixes: 539914240a01 ("serial: core: Fix probing serial_base_bus devices")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Message-ID: <18318adb-ab2c-4dcc-9f96-498a13d16b80@moroto.mountain>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: core: don't kfree device managed data

The put_device() function will call serial_base_ctrl_release() or
serial_base_port_release() so these kfrees() are a double free bug.

Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Message-ID: <ZH7tsTmWY5b/4m+6@moroto>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: core: Fix probing serial_base_bus devices

If a physical serial port device driver uses arch_initcall() we fail to
probe the serial_base_bus devices and the serial port tx fails. This is
because as serial_base_bus uses module_initcall().

Let's fix the issue by changing serial_base_bus to use arch_initcall().

Let's also return an error if a driver attempts to call uart_add_one_port()
too early.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Closes: https://lore.kernel.org/linux-serial/20230601132012.GB14287@atomide.com/T/#m6a40440fc04d551d27b147da8602e065c982a115
Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM")
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20230601141445.11321-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: core: Start managing serial controllers to enable runtime PM

We want to enable runtime PM for serial port device drivers in a generic
way. To do this, we want to have the serial core layer manage the
registered physical serial controller devices.

To manage serial controllers, let's set up a struct bus and struct device
for the serial core controller as suggested by Greg and Jiri. The serial
core controller devices are children of the physical serial port device.
The serial core controller device is needed to support multiple different
kind of ports connected to single physical serial port device.

Let's also set up a struct device for the serial core port. The serial
core port instances are children of the serial core controller device.

With the serial core port device we can now flush pending TX on the
runtime PM resume as suggested by Johan.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Jiri Slaby <jirislaby@kernel.org>
Suggested-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230525113034.46880-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>