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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1 3/4] xen/arm: Add SCIFA UART support for early printk
On Tue, Aug 7, 2018 at 4:48 PM, Julien Grall <julien.grall@xxxxxxx> wrote: > Hi, Hi, Julien > > On 06/08/18 19:35, Oleksandr Tyshchenko wrote: >> >> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx> >> >> Add support for Renesas "Stout" development board based on >> R-Car H2 SoC which has SCIFA compatible UART. >> >> Actually existing SCIF UART support (debug-scif.inc) and >> newly added SCIFA UART support (debug-scifa.inc) differ only >> in registers offsets. > > In that case, could we just extend debug-scif.inc? I was thinking about that, but couldn't find suitable solution without adding extra config option. As I understand, we need to recognize in run-time somehow which interface is present to use proper register offsets, so in UART driver it is easy to recognize using device-tree compatible string, but what to do here in such an early code. > >> >> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx> >> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx> >> CC: Julien Grall <julien.grall@xxxxxxx> >> --- >> docs/misc/arm/early-printk.txt | 3 ++- >> xen/arch/arm/Rules.mk | 1 + >> xen/arch/arm/arm32/debug-scifa.inc | 51 >> ++++++++++++++++++++++++++++++++++++++ >> 3 files changed, 54 insertions(+), 1 deletion(-) >> create mode 100644 xen/arch/arm/arm32/debug-scifa.inc >> >> diff --git a/docs/misc/arm/early-printk.txt >> b/docs/misc/arm/early-printk.txt >> index f765f59..f1b55d3 100644 >> --- a/docs/misc/arm/early-printk.txt >> +++ b/docs/misc/arm/early-printk.txt >> @@ -39,12 +39,13 @@ the name of the machine: >> - fastmodel: printk on ARM Fastmodel software emulators >> - hikey960: printk with pl011 with Hikey 960 >> - juno: printk with pl011 on Juno platform >> - - lager: printk with SCIF0 on Renesas R-Car H2 processors >> + - lager: printk with SCIF0 on Renesas Lager board (R-Car H2 processor) > > > Why this change? This sentence was not entirely correct. Since SCIF0 interface is applicable for Lager board, but is not applicable for Stout board which also based on R-Car H2 processor. Shall I create a separate patch for this small correction? > >> - midway: printk with the pl011 on Calxeda Midway processors >> - mvebu: printk with the MVEBU for Marvell Armada 3700 SoCs >> - omap5432: printk with UART3 on TI OMAP5432 processors >> - rcar3: printk with SCIF2 on Renesas R-Car Gen3 processors >> - seattle: printk with pl011 for AMD Seattle processor >> + - stout: printk with SCIFA0 on Renesas Stout board (R-Car H2 processor) > > > I have started to look at porting that to Kconfig ealyprintk and it is a > massive pain. So I would tend to prefer if we avoid adding more convenience > alias and instead document on the wiki page how to use earlyprintk for that. I will update a wiki page. Shall I drop this string in early-printk.txt? > > >> - sun6i: printk with 8250 on Allwinner A31 processors >> - sun7i: printk with 8250 on Allwinner A20 processors >> - thunderx: printk with pl011 for Cavium ThunderX processor >> diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk >> index f264592..e011f8b 100644 >> --- a/xen/arch/arm/Rules.mk >> +++ b/xen/arch/arm/Rules.mk >> @@ -40,6 +40,7 @@ EARLY_PRINTK_mvebu := mvebu,0xd0012000 >> EARLY_PRINTK_omap5432 := 8250,0x48020000,2 >> EARLY_PRINTK_rcar3 := scif,0xe6e88000 >> EARLY_PRINTK_seattle := pl011,0xe1010000 >> +EARLY_PRINTK_stout := scifa,0xe6c40000 >> EARLY_PRINTK_sun6i := 8250,0x01c28000,2 >> EARLY_PRINTK_sun7i := 8250,0x01c28000,2 >> EARLY_PRINTK_thunderx := pl011,0x87e024000000 >> diff --git a/xen/arch/arm/arm32/debug-scifa.inc >> b/xen/arch/arm/arm32/debug-scifa.inc >> new file mode 100644 >> index 0000000..b5e60db >> --- /dev/null >> +++ b/xen/arch/arm/arm32/debug-scifa.inc >> @@ -0,0 +1,51 @@ >> +/* >> + * xen/arch/arm/arm32/debug-scifa.inc >> + * >> + * SCIFA specific debug code >> + * >> + * Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx> >> + * Copyright (C) 2018 EPAM Systems Inc. >> + * >> + * This program is free software; you can redistribute it and/or modify >> + * it under the terms of the GNU General Public License as published by >> + * the Free Software Foundation; either version 2 of the License, or >> + * (at your option) any later version. >> + * >> + * This program is distributed in the hope that it will be useful, >> + * but WITHOUT ANY WARRANTY; without even the implied warranty of >> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the >> + * GNU General Public License for more details. >> + */ >> + >> +#include <asm/scif-uart.h> >> + >> +/* >> + * SCIFA UART wait UART to be ready to transmit >> + * rb: register which contains the UART base address >> + * rc: scratch register >> + */ >> +.macro early_uart_ready rb rc >> +1: >> + ldrh \rc, [\rb, #SCIFA_SCASSR] /* <- SCASSR (status register) >> */ >> + tst \rc, #SCASSR_TDFE /* Check TDFE bit */ >> + beq 1b /* Wait for the UART to be >> ready */ >> +.endm >> + >> +/* >> + * SCIFA UART transmit character >> + * rb: register which contains the UART base address >> + * rt: register which contains the character to transmit >> + */ >> +.macro early_uart_transmit rb rt >> + strb \rt, [\rb, #SCIFA_SCAFTDR] /* -> SCAFTDR >> (data register) */ >> + ldrh \rt, [\rb, #SCIFA_SCASSR] /* <- SCASSR >> (status register) */ >> + and \rt, \rt, #(~(SCASSR_TEND | SCASSR_TDFE)) /* Clear TEND >> and TDFE bits */ >> + strh \rt, [\rb, #SCIFA_SCASSR] /* -> SCASSR >> (status register) */ >> +.endm >> + >> +/* >> + * Local variables: >> + * mode: ASM >> + * indent-tabs-mode: nil >> + * End: >> + */ >> > > Cheers, > > -- > Julien Grall -- Regards, Oleksandr Tyshchenko _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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