| Message ID | 1441974053-2630-4-git-send-email-kernel@martin.sperl.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 09/11/2015 05:20 AM, kernel@martin.sperl.org wrote: > From: Martin Sperl <kernel@martin.sperl.org> > > Add the auxiliary uart1 device to the device tree of the bcm2835 SOC. > diff --git a/arch/arm/boot/dts/bcm2835.dtsi b/arch/arm/boot/dts/bcm2835.dtsi > + uart1: uart@7e215040 { > + compatible = "ns16550"; compatible should always include a precise HW-specific value; something like brcm,bcm2835-aux-uart. That way, if we find some other issue that needs working around on this HW in the future, all DTs will already contain the compatible value that SW needs in order to trigger that workaround. That's a generally true statement; i.e. irrespective of anything else in this series. I don't believe "ns16550" should be in the compatible value for this device, since the device cannot be successfully driven by SW that only knows about a standard 16650 UART. SW must know about the different divider, and there is no possibility of SW knowing about that before this series.
On 22.09.2015 04:42, Stephen Warren wrote: > On 09/11/2015 05:20 AM, kernel@martin.sperl.org wrote: >> From: Martin Sperl <kernel@martin.sperl.org> >> >> Add the auxiliary uart1 device to the device tree of the bcm2835 SOC. > >> diff --git a/arch/arm/boot/dts/bcm2835.dtsi b/arch/arm/boot/dts/bcm2835.dtsi > >> + uart1: uart@7e215040 { >> + compatible = "ns16550"; > > compatible should always include a precise HW-specific value; something > like brcm,bcm2835-aux-uart. That way, if we find some other issue that > needs working around on this HW in the future, all DTs will already > contain the compatible value that SW needs in order to trigger that > workaround. That's a generally true statement; i.e. irrespective of > anything else in this series. > > I don't believe "ns16550" should be in the compatible value for this > device, since the device cannot be successfully driven by SW that only > knows about a standard 16650 UART. SW must know about the different > divider, and there is no possibility of SW knowing about that before > this series. > OK - I will look into creating a separate driver then that uses the 8250 implementation as a basis...
On 09/23/2015 04:01 AM, Martin Sperl wrote: > On 22.09.2015 04:42, Stephen Warren wrote: >> On 09/11/2015 05:20 AM, kernel@martin.sperl.org wrote: >>> From: Martin Sperl <kernel@martin.sperl.org> >>> >>> Add the auxiliary uart1 device to the device tree of the bcm2835 SOC. >> >>> diff --git a/arch/arm/boot/dts/bcm2835.dtsi >>> b/arch/arm/boot/dts/bcm2835.dtsi >> >>> + uart1: uart@7e215040 { >>> + compatible = "ns16550"; >> >> compatible should always include a precise HW-specific value; something >> like brcm,bcm2835-aux-uart. That way, if we find some other issue that >> needs working around on this HW in the future, all DTs will already >> contain the compatible value that SW needs in order to trigger that >> workaround. That's a generally true statement; i.e. irrespective of >> anything else in this series. >> >> I don't believe "ns16550" should be in the compatible value for this >> device, since the device cannot be successfully driven by SW that only >> knows about a standard 16650 UART. SW must know about the different >> divider, and there is no possibility of SW knowing about that before >> this series. >> > > OK - I will look into creating a separate driver then that uses the 8250 > implementation as a basis... I expect all you need to do is add a new PORT_* value to the existing driver (which then drives some new quirk setting re: the clock rate), and add new entry for the compatible value in of_platform_serial_table[] in drivers/tty/serial/of_serial.c to select the correct TYPE_*.
diff --git a/arch/arm/boot/dts/bcm2835.dtsi b/arch/arm/boot/dts/bcm2835.dtsi index 3f5a7f1..d68e30c 100644 --- a/arch/arm/boot/dts/bcm2835.dtsi +++ b/arch/arm/boot/dts/bcm2835.dtsi @@ -185,6 +185,17 @@ compatible = "arm,arm1176-pmu"; }; + uart1: uart@7e215040 { + compatible = "ns16550"; + reg = <0x7e215040 0x40>; + reg-shift = <2>; + interrupts = <1 29>; + no-loopback-test; + status = "disabled"; + clock-divider = <8>; + clocks = <&aux_clocks BCM2835_AUX_CLOCK_UART>; + }; + spi1: spi@7e215080 { compatible = "brcm,bcm2835-aux-spi"; reg = <0x7e215080 0x40>;