On Tue, Jan 14, 2020 at 1:57 PM Christian Mauderer < christian.maude...@embedded-brains.de> wrote:
> On 13/01/2020 19:04, Niteesh wrote: > > The ns16550_context already has a field named baud_divisor, so if the > > user passes > > value for it, then we can skip the GetBaudDivisor function and use that > > value instead. > > > > Is this approach okay? > > Is the driver still able to handle different baud rates with this? Does > the ioctl call for setting the baudrate work? I didn't think about this, it won't work if we are using this method. ns16550_set_attributes calls ns16550_GetBaudDivisor, then I think we will have to stick with the old method. > > Best regards > > Christian > > > > > On Mon, Jan 13, 2020 at 3:46 PM Niteesh <gsnb...@gmail.com > > <mailto:gsnb...@gmail.com>> wrote: > > > > On Mon, Jan 13, 2020 at 1:38 PM Christian Mauderer > > <christian.maude...@embedded-brains.de > > <mailto:christian.maude...@embedded-brains.de>> wrote: > > > > On 12/01/2020 21:26, Niteesh wrote: > > > On Sun, Jan 12, 2020 at 11:42 PM Christian Mauderer > > <l...@c-mauderer.de <mailto:l...@c-mauderer.de> > > > <mailto:l...@c-mauderer.de <mailto:l...@c-mauderer.de>>> > wrote: > > > > > > Hello Niteesh, > > > > > > On 12/01/2020 16:06, Niteesh wrote: > > > > The only issue, I faced while using this driver is the > > baud divisor is > > > > calculated > > > > by CLOCK_FREQ/(BAUD_RATE * 16) (*ns16550-context.c:68)* > > > > but it should BAUD_DIV = (CLOCK_FREQ/(8 * BAUD_RATE)) - > > 1, for Rpi3. > > > > For testing, I assigned the baud divisor to 270 (115200 > > bits/s) in > > > > ns16550-context.c, > > > > and everything works fine. > > > > > > Sounds great. In NS16550_GetBaudDivisor there is already a > > case where > > > the baudDivisor is calculated differently (depending on > > > ctx->has_precision_clock_synthesizer and > > > ctx->has_fractional_divider_register). If none of the two > > cases are ok > > > for the controller you could just add another one. > > > > > > Can we pass in a function, which gets called, won't this be > more > > > flexible? because > > > in the future if we have some other board that has a different > > > calculation for the baud rate > > > the function will take care of it. > > > > It's possible. Please make sure to be compatible with the > > current API. > > For example if the pointer is NULL you should call the legacy > > function > > instead. > > > > > > I will be adding an extra field, a function pointer to > ns16550_context, > > the prototype of the function would be *uint32_t > > calculate_baud_divisor( ns16550_context * )* > > This is will calculate the baud divisor using its own formula and > > the initial baud. > > If this function is not NULL then it would be called inside > > *NS16550_GetBaudDivisor* function, > > * > > * > > > > > > > > > > > > > For console selection, my plan is to search for the aux > > node using > > > > compatible > > > > property and if its status is enabled, then initialize > > the AUX > > > uart and > > > > set the BSP_output_char > > > > to aux_output_char, else pl011_output_char. All this > > will be done > > > inside > > > > the uart_probe function, > > > > except for the initialization of AUX which will be done > in > > > init_ctx_aux. > > > > And finally, call the output char > > > > function using *BSP_output_char. Do you have any neat > > way to do this? > > > > > > I don't have an example for a similar case at hand. So: > > No, no neat way > > > that I can tell you. > > > > > > Before you start to write code: Please take a look at the > > different > > > beagle variants what is possible. Is there a variant where > > AUX uart > > > would be there but shouldn't be used as a console (one of > > the Zeros > > > maybe or the compute module?). How does Raspbian or > > FreeBSD decide which > > > port should be used? Maybe they decide based on the > > commandline.txt? In > > > such a case it would be better to just initialize all > > active (in the > > > fdt) serial ports and decide based on the commandline too. > > > > > > > > > The Documentation says the following: > > > *By default, on Raspberry Pis equipped with the > > wireless/Bluetooth* > > > *module (Raspberry Pi 3 and Raspberry Pi Zero W), **the PL011 > > UART is* > > > *connected to the Bluetooth module, while the mini UART is > > used as the > > > primary UART and* > > > *will have a Linux console on it. On all other models, the > > PL011 is used > > > as the primary UART. > > > > > > * > > > *In Linux device terms, by default, /dev/ttyS0 refers to the > > mini UART, > > > and /dev/ttyAMA0 refers* > > > *to the PL011. The primary UART is the one assigned to the > Linux > > > console, which depends on* > > > *the Raspberry Pi model as described above. There are also > > symlinks: > > > /dev/serial0, which always* > > > *refers to the primary UART (if enabled), and /dev/serial1, > which > > > similarly always refers to the secondary UART (if enabled).* > > > * > > > * > > > I checked in all the DTB files, by decompiling them (files are > > > from https://github.com/raspberrypi/firmware/tree/master/boot > ). > > > In all board with support for wireless and bluetooth, the AuX > > is enabled > > > and serial0 points to it. So we could use serial0 > > > to find the correct UART port. I think this is solid enough. > > So, should > > > I use this approach? > > > > Sounds OK. If possible please initialize the other UART too if > it is > > enabled in the FDT. Although we don't support bluetooth yet > > maybe there > > will be support in the future or someone wants to do it in the > > application. > > > > I will go with this method then. > > > > > > > > Or if using the command line, then we need to move the link to > > > CONSOLE_DEVICE to console_initialize, and parse the > > > command line twice. If this is no problem, then we could use > this > > > approach also. > > > > Would be possible too. > > > > > > > > > > > > > And why don't we have a function similar > > to *of_device_is_available*, > > > > since there will be more and more > > > > FDT based boards, this will be really helpful. > > > > > > I agree that it would be helpful. Seems that you just > > found a function > > > that should be in a FDT framework. > > > > > > RTEMS currently only has the basic libfdt functions and > > some RTEMS > > > specific ones. The of_... functions belong to the FreeBSD > > "Open Firmware > > > Bus" which is an abstraction layer on top of FDT. It would > > be great to > > > identify useful ones and port them or provide an RTEMS > > implementation. > > > Like already discussed this could be part of a GSoC > project. > > > > > > Best regards > > > > > > Christian > > > > > > > > > > > On Sun, Jan 5, 2020 at 12:57 AM Christian Mauderer > > > <l...@c-mauderer.de <mailto:l...@c-mauderer.de> > > <mailto:l...@c-mauderer.de <mailto:l...@c-mauderer.de>> > > > > <mailto:l...@c-mauderer.de <mailto:l...@c-mauderer.de> > > <mailto:l...@c-mauderer.de <mailto:l...@c-mauderer.de>>>> wrote: > > > > > > > > On 04/01/2020 09:32, Niteesh wrote: > > > > > We could now run RTEMS on Rpi3. I tried examples > > from the > > > samples > > > > > section and they run > > > > > fine. But still, a lot of functionality has to > > tested since it > > > > uses the > > > > > RPI2 BSP. To test these examples > > > > > I used a simple driver for the AUX. > > > > > The documentation from BCM link > > > > > > > > > > > > > > < > https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf > > (pg > > > > > no 10) states that > > > > > > > > > > > > > > > *The implemented UART is not a 16650 > > compatible UART However > > > > as far > > > > > as possible the first 8 control and status > > registers are > > > laid out > > > > > like a 16550 UART.* > > > > > > > > It also tells > > > > > > > > "Al 16550 register bits which are not supported > > can be > > > written but > > > > will be ignored and read back as 0. All control bits > for > > > simple UART > > > > receive/transmit operations are available." > > > > > > > > So I would expect that not everything works like > > expected (for > > > example > > > > setting DCD, DSR, DTR, RI - they are not there for > > the mini > > > UART) but > > > > the basic stuff should work. > > > > > > > > > > > > > > > > > > > My question is can we use the existing ns16550 > > driver or > > > should I > > > > create > > > > > a new one? I also checked the address of the > > registers the > > > offsets > > > > don't > > > > > seem right to me, but someone should check and > > correct me if > > > I am > > > > wrong. > > > > > > > > If you compare the registers in the existing driver > > > > (NS16550_RECEIVE_BUFFER, ... in ns16550_p.h) and the > > one in > > > the BCM > > > > datasheet the registers look very similar (at least > > from the > > > position / > > > > function). I haven't done a bit by bit comparison > > yet. Please > > > note that > > > > you have to do a conversion between the defines and > > register > > > addresses. > > > > The define gives you a register index for a 32bit > > register. So > > > you have > > > > to multiply by 4 to get an address. The driver is > > designed > > > that you > > > > provide a setRegister and getRegister function that > > can do this > > > > conversion. > > > > > > > > Where did you find differences? > > > > > > > > I would suggest to just try the driver. > > > > > > > > > > > > > _______________________________________________ > > > devel mailing list > > > devel@rtems.org <mailto:devel@rtems.org> > > > http://lists.rtems.org/mailman/listinfo/devel > > > > > > > -- > > -------------------------------------------- > > embedded brains GmbH > > Herr Christian Mauderer > > Dornierstr. 4 > > D-82178 Puchheim > > Germany > > email: christian.maude...@embedded-brains.de > > <mailto:christian.maude...@embedded-brains.de> > > Phone: +49-89-18 94 741 - 18 > > Fax: +49-89-18 94 741 - 08 > > PGP: Public key available on request. > > > > Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des > > EHUG. > > > > -- > -------------------------------------------- > embedded brains GmbH > Herr Christian Mauderer > Dornierstr. 4 > D-82178 Puchheim > Germany > email: christian.maude...@embedded-brains.de > Phone: +49-89-18 94 741 - 18 > Fax: +49-89-18 94 741 - 08 > PGP: Public key available on request. > > Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG. >
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