Hi, On 11/5/20 11:46 AM, AKASHI Takahiro wrote: > Hi Oleksandr, > > On Thu, Nov 05, 2020 at 09:18:39AM +0000, Oleksandr Andrushchenko wrote: >> Hello, >> >> On 11/4/20 7:24 AM, AKASHI Takahiro wrote: >>> sbsa-uart is a virtual UART device with a sub-set of PL011 functionality >>> which is described in SBSA (Server Base System Architecture)[1]. >>> >>> It mainly targets for server use, but sbsa-uart itself is useful in any >>> para-virtualized use cases, including Xen. >>> >>> At present, this patch is submitted as RFC because: >>> * for some reason, data cache must be turned off (in initr_dcache()) >> Can it be because of data cache maintenance is required? Please see [1] for >> >> more details, just a key note from there (Julien Grall): >> >> "Per the hypercall ABI (see include/public/arch-arm.h) all the buffers must >> reside in memory which is mapped as Normal Inner Write-Back Inner-Shareable. >> You are passing non-cacheable memory, so the behavior you see is expected." > Please note that, as far as this patch is concerned, no hypervisor call > is used. What is done here is that all the accesses to memory mapped > sbsa-uart registers are trapped and emulated by the hypervisor (in my case, > Xen's mmio handler).
The only reason I mentioned [1] is that I think it could be related to what you see, e.g. you need to switch off D-cache completely which makes me think we violate the ABI somehow > >> Thank you, > BTW, what do you think of this patch? It is good when it works with D-cache ON ;) Thank you, Oleksandr > > -Takahiro Akashi > >> Oleksandr >> >>> * there is a prerequisite patch for Xen[2] >>> >>> The patch with xenguest_arm64_defconfig was tested on upstream Xen and >>> qemu-arm64. >>> (To work with xenguest_arm64_defconfig, minor and non-essential tweaks >>> are needed.) >>> >>> The output looks like: >>> U-Boot 2021.01-rc1-00005-g3b8e3cde5345 (Nov 04 2020 - 13:54:44 +0900) >>> xenguest >>> >>> Xen virtual CPU >>> Model: XENVM-4.15 >>> DRAM: 128 MiB >>> PVBLOCK: Failed to read device/vbd directory: ENOENT >>> >>> In: sbsa-pl011 >>> Out: sbsa-pl011 >>> Err: sbsa-pl011 >>> xenguest# dm tree >>> Class Index Probed Driver Name >>> ----------------------------------------------------------- >>> root 0 [ + ] root_driver root_driver >>> firmware 0 [ ] psci |-- psci >>> serial 0 [ + ] serial_pl01x |-- sbsa-pl011 >>> pvblock 0 [ ] pvblock `-- pvblock >>> >>> [1] >>> https://urldefense.com/v3/__https://developer.arm.com/architectures/platform-design/server-systems__;!!GF_29dbcQIUBPA!k49FI4LUby7RffCuUHhIeq1ucvB2hhtch27HKXm3RBDLSY04ge4taCv7zqzDTat-6ZlDP1E68A$ >>> [developer[.]arm[.]com] >>> [2] >>> https://urldefense.com/v3/__https://lists.xenproject.org/archives/html/xen-devel/2020-10/msg02122.html__;!!GF_29dbcQIUBPA!k49FI4LUby7RffCuUHhIeq1ucvB2hhtch27HKXm3RBDLSY04ge4taCv7zqzDTat-6ZlHuV_0Rg$ >>> [lists[.]xenproject[.]org] >>> >>> Signed-off-by: AKASHI Takahiro <takahiro.aka...@linaro.org> >>> --- >>> drivers/serial/Kconfig | 13 +++++++++++-- >>> drivers/serial/serial_pl01x.c | 16 +++++++++++++--- >>> include/dm/platform_data/serial_pl01x.h | 1 + >>> 3 files changed, 25 insertions(+), 5 deletions(-) >>> >>> diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig >>> index b4805a2e4ea4..fb570174c577 100644 >>> --- a/drivers/serial/Kconfig >>> +++ b/drivers/serial/Kconfig >>> @@ -332,6 +332,15 @@ config DEBUG_UART_PL011 >>> work. The driver will be available until the real driver model >>> serial is running. >>> >>> +config DEBUG_UART_SBSA >>> + bool "sbsa-uart" >>> + depends on PL01X_SERIAL >>> + help >>> + Select this to enable a debug UART using the pl01x driver with the >>> + SBSA_UART type. You will need to provide parameters to make this >>> + work. The driver will be available until the real driver model >>> + serial is running. >>> + >>> config DEBUG_UART_PIC32 >>> bool "Microchip PIC32" >>> depends on PIC32_SERIAL >>> @@ -415,7 +424,7 @@ config DEBUG_UART_BASE >>> >>> config DEBUG_UART_CLOCK >>> int "UART input clock" >>> - depends on DEBUG_UART >>> + depends on DEBUG_UART && !DEBUG_UART_SBSA >>> default 0 if DEBUG_UART_SANDBOX >>> help >>> The UART input clock determines the speed of the internal UART >>> @@ -427,7 +436,7 @@ config DEBUG_UART_CLOCK >>> >>> config DEBUG_UART_SHIFT >>> int "UART register shift" >>> - depends on DEBUG_UART >>> + depends on DEBUG_UART && !DEBUG_UART_SBSA >>> default 0 if DEBUG_UART >>> help >>> Some UARTs (notably ns16550) support different register layouts >>> diff --git a/drivers/serial/serial_pl01x.c b/drivers/serial/serial_pl01x.c >>> index 2772c25f1d2d..5ef4ae0c6a65 100644 >>> --- a/drivers/serial/serial_pl01x.c >>> +++ b/drivers/serial/serial_pl01x.c >>> @@ -84,6 +84,8 @@ static int pl01x_generic_serial_init(struct pl01x_regs >>> *regs, >>> /* disable everything */ >>> writel(0, ®s->pl011_cr); >>> break; >>> + case TYPE_SBSA_UART: >>> + break; >>> default: >>> return -EINVAL; >>> } >>> @@ -146,7 +148,8 @@ static int pl01x_generic_setbrg(struct pl01x_regs >>> *regs, enum pl01x_type type, >>> writel(UART_PL010_CR_UARTEN, ®s->pl010_cr); >>> break; >>> } >>> - case TYPE_PL011: { >>> + case TYPE_PL011: >>> + case TYPE_SBSA_UART: { >>> unsigned int temp; >>> unsigned int divider; >>> unsigned int remainder; >>> @@ -171,6 +174,9 @@ static int pl01x_generic_setbrg(struct pl01x_regs >>> *regs, enum pl01x_type type, >>> writel(fraction, ®s->pl011_fbrd); >>> } >>> >>> + if (type == TYPE_SBSA_UART) >>> + break; >>> + >>> pl011_set_line_control(regs); >>> /* Finally, enable the UART */ >>> writel(UART_PL011_CR_UARTEN | UART_PL011_CR_TXE | >>> @@ -340,6 +346,7 @@ static const struct dm_serial_ops pl01x_serial_ops = { >>> static const struct udevice_id pl01x_serial_id[] ={ >>> {.compatible = "arm,pl011", .data = TYPE_PL011}, >>> {.compatible = "arm,pl010", .data = TYPE_PL010}, >>> + {.compatible = "arm,sbsa-uart", .data = TYPE_SBSA_UART}, >>> {} >>> }; >>> >>> @@ -386,7 +393,8 @@ U_BOOT_DRIVER(serial_pl01x) = { >>> >>> #endif >>> >>> -#if defined(CONFIG_DEBUG_UART_PL010) || defined(CONFIG_DEBUG_UART_PL011) >>> +#if defined(CONFIG_DEBUG_UART_PL010) || defined(CONFIG_DEBUG_UART_PL011) >>> || \ >>> + defined(CONFIG_DEBUG_UART_SBSA) >>> >>> #include <debug_uart.h> >>> >>> @@ -395,7 +403,9 @@ static void _debug_uart_init(void) >>> #ifndef CONFIG_DEBUG_UART_SKIP_INIT >>> struct pl01x_regs *regs = (struct pl01x_regs *)CONFIG_DEBUG_UART_BASE; >>> enum pl01x_type type = CONFIG_IS_ENABLED(DEBUG_UART_PL011) ? >>> - TYPE_PL011 : TYPE_PL010; >>> + TYPE_PL011 : >>> + (CONFIG_IS_ENABLED(DEBUG_UART_PL010) ? >>> + TYPE_PL010 : TYPE_SBSA_UART); >>> >>> pl01x_generic_serial_init(regs, type); >>> pl01x_generic_setbrg(regs, type, >>> diff --git a/include/dm/platform_data/serial_pl01x.h >>> b/include/dm/platform_data/serial_pl01x.h >>> index 77d96c49f03a..4bacbd512400 100644 >>> --- a/include/dm/platform_data/serial_pl01x.h >>> +++ b/include/dm/platform_data/serial_pl01x.h >>> @@ -9,6 +9,7 @@ >>> enum pl01x_type { >>> TYPE_PL010, >>> TYPE_PL011, >>> + TYPE_SBSA_UART, >>> }; >>> >>> /* >> [1] >> https://urldefense.com/v3/__https://lists.xenproject.org/archives/html/xen-devel/2020-06/msg00737.html__;!!GF_29dbcQIUBPA!lcj5vFUVCdTMPJOPTAtfRwYakvC6UDkWYnpRHiIUfK52Z1iuT88ADHiisoe9-M-dEsQHPN0Atw$ >> [lists[.]xenproject[.]org]
