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SubjectRe: [PATCH v2 1/2] acpi, spcr: Make SPCR avialable to other architectures
[adding Lorenzo, Sudeep and Hanjun -- see Rafael's comment below]

On Wed, Dec 13, 2017 at 01:22:59AM +0100, Rafael J. Wysocki wrote:
> On Monday, December 11, 2017 4:50:58 PM CET Prarit Bhargava wrote:
> > Other architectures can use SPCR to setup an early console or console
> > but the current code is ARM64 specific.
> >
> > Change the name of parse_spcr() to acpi_parse_spcr(). Add a weak
> > function acpi_arch_setup_console() that can be used for arch-specific
> > setup. Move flags into ACPI code. Update the Documention on the use of
> > the SPCR.
> >
> > [v2]: Don't return an error in the baud_rate check of acpi_parse_spcr().
> > Keep ACPI_SPCR_TABLE selected for ARM64. Fix 8-bit port access width
> > mmio value. Move baud rate check earlier.
> >
> > Signed-off-by: Prarit Bhargava <prarit@redhat.com>
>
> This mostly affects ARM64, so ACKs from that side are requisite for it.
>
> > Cc: linux-doc@vger.kernel.org
> > Cc: linux-kernel@vger.kernel.org
> > Cc: linux-arm-kernel@lists.infradead.org
> > Cc: linux-pm@vger.kernel.org
> > Cc: linux-acpi@vger.kernel.org
> > Cc: linux-serial@vger.kernel.org
> > Cc: Bhupesh Sharma <bhsharma@redhat.com>
> > Cc: Lv Zheng <lv.zheng@intel.com>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Ingo Molnar <mingo@redhat.com>
> > Cc: "H. Peter Anvin" <hpa@zytor.com>
> > Cc: x86@kernel.org
> > Cc: Jonathan Corbet <corbet@lwn.net>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Will Deacon <will.deacon@arm.com>
> > Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> > Cc: Timur Tabi <timur@codeaurora.org>
> > ---
> > Documentation/admin-guide/kernel-parameters.txt | 6 +-
> > arch/arm64/kernel/acpi.c | 128 ++++++++++++++++-
> > drivers/acpi/Kconfig | 7 +-
> > drivers/acpi/spcr.c | 175 ++++++------------------
> > drivers/tty/serial/earlycon.c | 15 +-
> > include/linux/acpi.h | 11 +-
> > include/linux/serial_core.h | 2 -
> > 7 files changed, 184 insertions(+), 160 deletions(-)
> >
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index 6571fbfdb2a1..0d173289c67e 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -914,9 +914,9 @@
> >
> > earlycon= [KNL] Output early console device and options.
> >
> > - When used with no options, the early console is
> > - determined by the stdout-path property in device
> > - tree's chosen node.
> > + [ARM64] The early console is determined by the
> > + stdout-path property in device tree's chosen node,
> > + or determined by the ACPI SPCR table.
> >
> > cdns,<addr>[,options]
> > Start an early, polled-mode console on a Cadence
> > diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> > index b3162715ed78..b3e33bbdf3b7 100644
> > --- a/arch/arm64/kernel/acpi.c
> > +++ b/arch/arm64/kernel/acpi.c
> > @@ -25,7 +25,6 @@
> > #include <linux/memblock.h>
> > #include <linux/of_fdt.h>
> > #include <linux/smp.h>
> > -#include <linux/serial_core.h>
> >
> > #include <asm/cputype.h>
> > #include <asm/cpu_ops.h>
> > @@ -177,6 +176,128 @@ static int __init acpi_fadt_sanity_check(void)
> > return ret;
> > }
> >
> > +/*
> > + * Erratum 44 for QDF2432v1 and QDF2400v1 SoCs describes the BUSY bit as
> > + * occasionally getting stuck as 1. To avoid the potential for a hang, check
> > + * TXFE == 0 instead of BUSY == 1. This may not be suitable for all UART
> > + * implementations, so only do so if an affected platform is detected in
> > + * acpi_parse_spcr().
> > + */
> > +bool qdf2400_e44_present;
> > +EXPORT_SYMBOL(qdf2400_e44_present);
> > +
> > +/*
> > + * Some Qualcomm Datacenter Technologies SoCs have a defective UART BUSY bit.
> > + * Detect them by examining the OEM fields in the SPCR header, similar to PCI
> > + * quirk detection in pci_mcfg.c.
> > + */
> > +static bool qdf2400_erratum_44_present(struct acpi_table_header *h)
> > +{
> > + if (memcmp(h->oem_id, "QCOM ", ACPI_OEM_ID_SIZE))
> > + return false;
> > +
> > + if (!memcmp(h->oem_table_id, "QDF2432 ", ACPI_OEM_TABLE_ID_SIZE))
> > + return true;
> > +
> > + if (!memcmp(h->oem_table_id, "QDF2400 ", ACPI_OEM_TABLE_ID_SIZE) &&
> > + h->oem_revision == 1)
> > + return true;
> > +
> > + return false;
> > +}
> > +
> > +/*
> > + * APM X-Gene v1 and v2 UART hardware is an 16550 like device but has its
> > + * register aligned to 32-bit. In addition, the BIOS also encoded the
> > + * access width to be 8 bits. This function detects this errata condition.
> > + */
> > +static bool xgene_8250_erratum_present(struct acpi_table_spcr *tb)
> > +{
> > + bool xgene_8250 = false;
> > +
> > + if (tb->interface_type != ACPI_DBG2_16550_COMPATIBLE)
> > + return false;
> > +
> > + if (memcmp(tb->header.oem_id, "APMC0D", ACPI_OEM_ID_SIZE) &&
> > + memcmp(tb->header.oem_id, "HPE ", ACPI_OEM_ID_SIZE))
> > + return false;
> > +
> > + if (!memcmp(tb->header.oem_table_id, "XGENESPC",
> > + ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 0)
> > + xgene_8250 = true;
> > +
> > + if (!memcmp(tb->header.oem_table_id, "ProLiant",
> > + ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 1)
> > + xgene_8250 = true;
> > +
> > + return xgene_8250;
> > +}
> > +
> > +int acpi_arch_setup_console(struct acpi_table_spcr *table,
> > + char *opts, char *uart, char *iotype,
> > + int baud_rate, bool earlycon)
> > +{
> > + if (table->header.revision < 2) {
> > + pr_err("wrong table version\n");
> > + return -ENOENT;
> > + }
> > +
> > + switch (table->interface_type) {
> > + case ACPI_DBG2_ARM_SBSA_32BIT:
> > + snprintf(iotype, ACPI_SPCR_BUF_SIZE, "mmio32");
> > + /* fall through */
> > + case ACPI_DBG2_ARM_PL011:
> > + case ACPI_DBG2_ARM_SBSA_GENERIC:
> > + case ACPI_DBG2_BCM2835:
> > + snprintf(uart, ACPI_SPCR_BUF_SIZE, "pl011");
> > + break;
> > + default:
> > + if (strlen(uart) == 0)
> > + return -ENOENT;
> > + }
> > +
> > + /*
> > + * If the E44 erratum is required, then we need to tell the pl011
> > + * driver to implement the work-around.
> > + *
> > + * The global variable is used by the probe function when it
> > + * creates the UARTs, whether or not they're used as a console.
> > + *
> > + * If the user specifies "traditional" earlycon, the qdf2400_e44
> > + * console name matches the EARLYCON_DECLARE() statement, and
> > + * SPCR is not used. Parameter "earlycon" is false.
> > + *
> > + * If the user specifies "SPCR" earlycon, then we need to update
> > + * the console name so that it also says "qdf2400_e44". Parameter
> > + * "earlycon" is true.
> > + *
> > + * For consistency, if we change the console name, then we do it
> > + * for everyone, not just earlycon.
> > + */
> > + if (qdf2400_erratum_44_present(&table->header)) {
> > + qdf2400_e44_present = true;
> > + if (earlycon)
> > + snprintf(uart, ACPI_SPCR_BUF_SIZE, "qdf2400_e44");
> > + }
> > +
> > + if (xgene_8250_erratum_present(table)) {
> > + snprintf(iotype, ACPI_SPCR_BUF_SIZE, "mmio32");
> > +
> > + /* for xgene v1 and v2 we don't know the clock rate of the
> > + * UART so don't attempt to change to the baud rate state
> > + * in the table because driver cannot calculate the dividers
> > + */
> > + snprintf(opts, ACPI_SPCR_OPTS_SIZE, "%s,%s,0x%llx", uart,
> > + iotype, table->serial_port.address);
> > + } else {
> > + snprintf(opts, ACPI_SPCR_OPTS_SIZE, "%s,%s,0x%llx,%d", uart,
> > + iotype, table->serial_port.address, baud_rate);
> > + }
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL(acpi_arch_setup_console);
> > +
> > /*
> > * acpi_boot_table_init() called from setup_arch(), always.
> > * 1. find RSDP and get its address, and then find XSDT
> > @@ -230,10 +351,11 @@ void __init acpi_boot_table_init(void)
> >
> > done:
> > if (acpi_disabled) {
> > - if (earlycon_init_is_deferred)
> > + if (console_acpi_spcr_enable)
> > early_init_dt_scan_chosen_stdout();
> > } else {
> > - parse_spcr(earlycon_init_is_deferred);
> > + /* Always enable the ACPI SPCR console */
> > + acpi_parse_spcr(console_acpi_spcr_enable);
> > if (IS_ENABLED(CONFIG_ACPI_BGRT))
> > acpi_table_parse(ACPI_SIG_BGRT, acpi_parse_bgrt);
> > }
> > diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> > index 46505396869e..9ae98eeada76 100644
> > --- a/drivers/acpi/Kconfig
> > +++ b/drivers/acpi/Kconfig
> > @@ -79,7 +79,12 @@ config ACPI_DEBUGGER_USER
> > endif
> >
> > config ACPI_SPCR_TABLE
> > - bool
> > + bool "ACPI Serial Port Console Redirection Support"
> > + default y if ARM64
> > + help
> > + Enable support for Serial Port Console Redirection (SPCR) Table.
> > + This table provides information about the configuration of the
> > + earlycon console.
> >
> > config ACPI_LPIT
> > bool
> > diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
> > index 324b35bfe781..f4bb8110e404 100644
> > --- a/drivers/acpi/spcr.c
> > +++ b/drivers/acpi/spcr.c
> > @@ -16,65 +16,18 @@
> > #include <linux/kernel.h>
> > #include <linux/serial_core.h>
> >
> > -/*
> > - * Erratum 44 for QDF2432v1 and QDF2400v1 SoCs describes the BUSY bit as
> > - * occasionally getting stuck as 1. To avoid the potential for a hang, check
> > - * TXFE == 0 instead of BUSY == 1. This may not be suitable for all UART
> > - * implementations, so only do so if an affected platform is detected in
> > - * parse_spcr().
> > - */
> > -bool qdf2400_e44_present;
> > -EXPORT_SYMBOL(qdf2400_e44_present);
> > -
> > -/*
> > - * Some Qualcomm Datacenter Technologies SoCs have a defective UART BUSY bit.
> > - * Detect them by examining the OEM fields in the SPCR header, similiar to PCI
> > - * quirk detection in pci_mcfg.c.
> > - */
> > -static bool qdf2400_erratum_44_present(struct acpi_table_header *h)
> > -{
> > - if (memcmp(h->oem_id, "QCOM ", ACPI_OEM_ID_SIZE))
> > - return false;
> > -
> > - if (!memcmp(h->oem_table_id, "QDF2432 ", ACPI_OEM_TABLE_ID_SIZE))
> > - return true;
> > -
> > - if (!memcmp(h->oem_table_id, "QDF2400 ", ACPI_OEM_TABLE_ID_SIZE) &&
> > - h->oem_revision == 1)
> > - return true;
> > -
> > - return false;
> > -}
> > -
> > -/*
> > - * APM X-Gene v1 and v2 UART hardware is an 16550 like device but has its
> > - * register aligned to 32-bit. In addition, the BIOS also encoded the
> > - * access width to be 8 bits. This function detects this errata condition.
> > - */
> > -static bool xgene_8250_erratum_present(struct acpi_table_spcr *tb)
> > +int __weak acpi_arch_setup_console(struct acpi_table_spcr *table,
> > + char *opts, char *uart, char *iotype,
> > + int baud_rate, bool earlycon)
> > {
> > - bool xgene_8250 = false;
> > -
> > - if (tb->interface_type != ACPI_DBG2_16550_COMPATIBLE)
> > - return false;
> > -
> > - if (memcmp(tb->header.oem_id, "APMC0D", ACPI_OEM_ID_SIZE) &&
> > - memcmp(tb->header.oem_id, "HPE ", ACPI_OEM_ID_SIZE))
> > - return false;
> > -
> > - if (!memcmp(tb->header.oem_table_id, "XGENESPC",
> > - ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 0)
> > - xgene_8250 = true;
> > -
> > - if (!memcmp(tb->header.oem_table_id, "ProLiant",
> > - ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 1)
> > - xgene_8250 = true;
> > -
> > - return xgene_8250;
> > + snprintf(opts, ACPI_SPCR_OPTS_SIZE, "%s,%s,0x%llx,%d", uart, iotype,
> > + table->serial_port.address, baud_rate);
> > + return 0;
> > }
> >
> > +bool console_acpi_spcr_enable __initdata;
> > /**
> > - * parse_spcr() - parse ACPI SPCR table and add preferred console
> > + * acpi_parse_spcr() - parse ACPI SPCR table and add preferred console
> > *
> > * @earlycon: set up earlycon for the console specified by the table
> > *
> > @@ -86,13 +39,13 @@ static bool xgene_8250_erratum_present(struct acpi_table_spcr *tb)
> > * from arch initialization code as soon as the DT/ACPI decision is made.
> > *
> > */
> > -int __init parse_spcr(bool earlycon)
> > +int __init acpi_parse_spcr(bool earlycon)
> > {
> > - static char opts[64];
> > + static char opts[ACPI_SPCR_OPTS_SIZE];
> > + static char uart[ACPI_SPCR_BUF_SIZE];
> > + static char iotype[ACPI_SPCR_BUF_SIZE];
> > struct acpi_table_spcr *table;
> > acpi_status status;
> > - char *uart;
> > - char *iotype;
> > int baud_rate;
> > int err;
> >
> > @@ -105,48 +58,6 @@ int __init parse_spcr(bool earlycon)
> > if (ACPI_FAILURE(status))
> > return -ENOENT;
> >
> > - if (table->header.revision < 2) {
> > - err = -ENOENT;
> > - pr_err("wrong table version\n");
> > - goto done;
> > - }
> > -
> > - if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
> > - switch (ACPI_ACCESS_BIT_WIDTH((
> > - table->serial_port.access_width))) {
> > - default:
> > - pr_err("Unexpected SPCR Access Width. Defaulting to byte size\n");
> > - case 8:
> > - iotype = "mmio";
> > - break;
> > - case 16:
> > - iotype = "mmio16";
> > - break;
> > - case 32:
> > - iotype = "mmio32";
> > - break;
> > - }
> > - } else
> > - iotype = "io";
> > -
> > - switch (table->interface_type) {
> > - case ACPI_DBG2_ARM_SBSA_32BIT:
> > - iotype = "mmio32";
> > - /* fall through */
> > - case ACPI_DBG2_ARM_PL011:
> > - case ACPI_DBG2_ARM_SBSA_GENERIC:
> > - case ACPI_DBG2_BCM2835:
> > - uart = "pl011";
> > - break;
> > - case ACPI_DBG2_16550_COMPATIBLE:
> > - case ACPI_DBG2_16550_SUBSET:
> > - uart = "uart";
> > - break;
> > - default:
> > - err = -ENOENT;
> > - goto done;
> > - }
> > -
> > switch (table->baud_rate) {
> > case 3:
> > baud_rate = 9600;
> > @@ -165,43 +76,36 @@ int __init parse_spcr(bool earlycon)
> > goto done;
> > }
> >
> > - /*
> > - * If the E44 erratum is required, then we need to tell the pl011
> > - * driver to implement the work-around.
> > - *
> > - * The global variable is used by the probe function when it
> > - * creates the UARTs, whether or not they're used as a console.
> > - *
> > - * If the user specifies "traditional" earlycon, the qdf2400_e44
> > - * console name matches the EARLYCON_DECLARE() statement, and
> > - * SPCR is not used. Parameter "earlycon" is false.
> > - *
> > - * If the user specifies "SPCR" earlycon, then we need to update
> > - * the console name so that it also says "qdf2400_e44". Parameter
> > - * "earlycon" is true.
> > - *
> > - * For consistency, if we change the console name, then we do it
> > - * for everyone, not just earlycon.
> > - */
> > - if (qdf2400_erratum_44_present(&table->header)) {
> > - qdf2400_e44_present = true;
> > - if (earlycon)
> > - uart = "qdf2400_e44";
> > + switch (table->interface_type) {
> > + case ACPI_DBG2_16550_COMPATIBLE:
> > + case ACPI_DBG2_16550_SUBSET:
> > + snprintf(uart, ACPI_SPCR_BUF_SIZE, "uart");
> > + break;
> > + default:
> > + break;
> > }
> >
> > - if (xgene_8250_erratum_present(table)) {
> > - iotype = "mmio32";
> > + if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
> > + u8 width = ACPI_ACCESS_BIT_WIDTH((
> > + table->serial_port.access_width));
> > + switch (width) {
> > + default:
> > + pr_err("Unexpected SPCR Access Width. Defaulting to byte size\n");
> > + case 8:
> > + snprintf(iotype, ACPI_SPCR_BUF_SIZE, "mmio");
> > + break;
> > + case 16:
> > + case 32:
> > + snprintf(iotype, ACPI_SPCR_BUF_SIZE, "mmio%d", width);
> > + break;
> > + }
> > + } else
> > + snprintf(iotype, ACPI_SPCR_BUF_SIZE, "io");
> >
> > - /* for xgene v1 and v2 we don't know the clock rate of the
> > - * UART so don't attempt to change to the baud rate state
> > - * in the table because driver cannot calculate the dividers
> > - */
> > - snprintf(opts, sizeof(opts), "%s,%s,0x%llx", uart, iotype,
> > - table->serial_port.address);
> > - } else {
> > - snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
> > - table->serial_port.address, baud_rate);
> > - }
> > + err = acpi_arch_setup_console(table, opts, uart, iotype, baud_rate,
> > + earlycon);
> > + if (err)
> > + goto done;
> >
> > pr_info("console: %s\n", opts);
> >
> > @@ -209,7 +113,6 @@ int __init parse_spcr(bool earlycon)
> > setup_earlycon(opts);
> >
> > err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
> > -
> > done:
> > acpi_put_table((struct acpi_table_header *)table);
> > return err;
> > diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
> > index 4c8b80f1c688..b22afb62c7a3 100644
> > --- a/drivers/tty/serial/earlycon.c
> > +++ b/drivers/tty/serial/earlycon.c
> > @@ -196,26 +196,15 @@ int __init setup_earlycon(char *buf)
> > return -ENOENT;
> > }
> >
> > -/*
> > - * When CONFIG_ACPI_SPCR_TABLE is defined, "earlycon" without parameters in
> > - * command line does not start DT earlycon immediately, instead it defers
> > - * starting it until DT/ACPI decision is made. At that time if ACPI is enabled
> > - * call parse_spcr(), else call early_init_dt_scan_chosen_stdout()
> > - */
> > -bool earlycon_init_is_deferred __initdata;
> > -
> > /* early_param wrapper for setup_earlycon() */
> > static int __init param_setup_earlycon(char *buf)
> > {
> > int err;
> >
> > - /*
> > - * Just 'earlycon' is a valid param for devicetree earlycons;
> > - * don't generate a warning from parse_early_params() in that case
> > - */
> > + /* Just 'earlycon' is a valid param for devicetree and ACPI SPCR. */
> > if (!buf || !buf[0]) {
> > if (IS_ENABLED(CONFIG_ACPI_SPCR_TABLE)) {
> > - earlycon_init_is_deferred = true;
> > + console_acpi_spcr_enable = true;
> > return 0;
> > } else if (!buf) {
> > return early_init_dt_scan_chosen_stdout();
> > diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> > index dc1ebfeeb5ec..875d7327d91c 100644
> > --- a/include/linux/acpi.h
> > +++ b/include/linux/acpi.h
> > @@ -1241,10 +1241,17 @@ static inline bool acpi_has_watchdog(void) { return false; }
> > #endif
> >
> > #ifdef CONFIG_ACPI_SPCR_TABLE
> > +#define ACPI_SPCR_OPTS_SIZE 64
> > +#define ACPI_SPCR_BUF_SIZE 32
> > extern bool qdf2400_e44_present;
> > -int parse_spcr(bool earlycon);
> > +extern bool console_acpi_spcr_enable __initdata;
> > +extern int acpi_arch_setup_console(struct acpi_table_spcr *table,
> > + char *opts, char *uart, char *iotype,
> > + int baud_rate, bool earlycon);
> > +int acpi_parse_spcr(bool earlycon);
> > #else
> > -static inline int parse_spcr(bool earlycon) { return 0; }
> > +static const bool console_acpi_spcr_enable;
> > +static inline int acpi_parse_spcr(bool earlycon) { return 0; }
> > #endif
> >
> > #if IS_ENABLED(CONFIG_ACPI_GENERIC_GSI)
> > diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
> > index 37b044e78333..abfffb4b1c37 100644
> > --- a/include/linux/serial_core.h
> > +++ b/include/linux/serial_core.h
> > @@ -376,10 +376,8 @@ extern int of_setup_earlycon(const struct earlycon_id *match,
> > const char *options);
> >
> > #ifdef CONFIG_SERIAL_EARLYCON
> > -extern bool earlycon_init_is_deferred __initdata;
> > int setup_earlycon(char *buf);
> > #else
> > -static const bool earlycon_init_is_deferred;
> > static inline int setup_earlycon(char *buf) { return 0; }
> > #endif
> >
> >
>
>

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