[Skiboot] [PATCH V6 02/21] hw/ast-bmc: Initialize ast lpc mctp binding
Christophe Lombard
clombard at linux.vnet.ibm.com
Wed Apr 12 17:45:22 AEST 2023
Le 06/04/2023 à 19:16, Frederic Barrat a écrit :
>
>
> On 13/09/2022 12:26, Christophe Lombard wrote:
>> The Management Component Transport Protocol (MCTP) defines a
>> communication
>> model intended to facilitate communication.
>>
>> This patch initialize MCTP binding over LPC Bus interface.
>>
>> Several steps must be performed:
>> - Initialize the MCTP core (mctp_init()).
>> - Initialize a hardware binding as AST LPC mode host
>> (mctp_astlpc_init()).
>> - Register the hardware binding with the core (mctp_register_bus()),
>> using
>> a predefined EID (Host default is 9).
>>
>> To transmit a MCTP message, mctp_message_tx() is used.
>> To receive a MCTP message, a callback need to be provided and registered
>> through mctp_set_rx_all().
>>
>> For the transfer of MCTP messages, two basics components are used:
>> - A window of the LPC FW address space, where reads and writes are
>> forwarded to BMC memory.
>> - An interrupt mechanism using the KCS interface.
>>
>> hw/ast-bmc/ast-mctp.c is compilated if the compiler flag CONFIG_PLDM is
>> set.
>>
>> Signed-off-by: Christophe Lombard <clombard at linux.vnet.ibm.com>
>> ---
>> hw/ast-bmc/Makefile.inc | 7 +
>> hw/ast-bmc/ast-mctp.c | 386 ++++++++++++++++++++++++++++++++++++++++
>> include/ast.h | 11 ++
>> 3 files changed, 404 insertions(+)
>> create mode 100644 hw/ast-bmc/ast-mctp.c
>>
>> diff --git a/hw/ast-bmc/Makefile.inc b/hw/ast-bmc/Makefile.inc
>> index e7ded0e8..546f2bc7 100644
>> --- a/hw/ast-bmc/Makefile.inc
>> +++ b/hw/ast-bmc/Makefile.inc
>> @@ -2,5 +2,12 @@
>> SUBDIRS += hw/ast-bmc
>> AST_BMC_OBJS = ast-io.o ast-sf-ctrl.o
>> +
>> +ifeq ($(CONFIG_PLDM),1)
>> +CPPFLAGS += -I$(SRC)/libmctp/
>> +#CFLAGS += -DAST_MCTP_DEBUG
>> +AST_BMC_OBJS += ast-mctp.o
>> +endif
>> +
>> AST_BMC = hw/ast-bmc/built-in.a
>> $(AST_BMC): $(AST_BMC_OBJS:%=hw/ast-bmc/%)
>> diff --git a/hw/ast-bmc/ast-mctp.c b/hw/ast-bmc/ast-mctp.c
>> new file mode 100644
>> index 00000000..1e7bdb51
>> --- /dev/null
>> +++ b/hw/ast-bmc/ast-mctp.c
>> @@ -0,0 +1,386 @@
>> +// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
>> +// Copyright 2022 IBM Corp.
>> +
>> +#define pr_fmt(fmt) "AST-MCTP: " fmt
>> +
>> +#include <lpc.h>
>> +#include <interrupts.h>
>> +#include <timer.h>
>> +#include <timebase.h>
>> +#include <debug_descriptor.h>
>> +#include <ast.h>
>> +#include <console.h>
>> +#include <libmctp.h>
>> +#include <libmctp-cmds.h>
>> +#include <libmctp-log.h>
>> +#include <libmctp-astlpc.h>
>> +
>> +/*
>> + * For the EIDs: the valid range is 8-254.
>> + * host default = 9
>> + */
>> +uint8_t HOST_EID = 9;
>> +
>> +struct timer ast_boot_timer;
>> +static struct mctp *mctp;
>> +
>> +struct ast_mctp_backend {
>> + bool (*ready)(void);
>> + int (*binding)(void);
>> + void (*destroy)(void);
>> +};
>> +const struct ast_mctp_backend *mctp_backend;
>> +
>> +/*
>> + * The AST LPC binding is described here:
>> + *
>> + *
>> https://github.com/openbmc/libmctp/blob/master/docs/bindings/vendor-astlpc.md
>
>
> The correct URL is now:
> https://github.com/openbmc/libmctp/blob/master/docs/bindings/vendor-ibm-astlpc.md
>
>
Thanks.
>
>> + *
>> + * Most of the binding is implemented in libmctp, but we need to
>> provide
>> + * accessors for the LPC FW space (for the packet buffer) and for
>> the KCS
>> + * peripheral (for the interrupt mechanism).
>> + */
>> +
>> +struct astlpc_ops_data {
>> + uint16_t kcs_data_addr; /* LPC IO space offset for the data
>> register */
>> + uint16_t kcs_stat_addr;
>> +
>> + /* address of the packet exchange buffer in FW space */
>> + uint32_t lpc_fw_addr;
>> +};
>> +
>> +static int astlpc_kcs_reg_read(void *binding_data,
>> + enum mctp_binding_astlpc_kcs_reg reg,
>> + uint8_t *val)
>> +{
>> + struct astlpc_ops_data *ops_data = binding_data;
>> + uint32_t addr, tmp;
>> + int rc;
>> +
>> + if (reg == MCTP_ASTLPC_KCS_REG_STATUS)
>> + addr = ops_data->kcs_stat_addr;
>> + else if (reg == MCTP_ASTLPC_KCS_REG_DATA)
>> + addr = ops_data->kcs_data_addr;
>> + else
>> + return OPAL_PARAMETER;
>> +
>> + rc = lpc_read(OPAL_LPC_IO, addr, &tmp, 1);
>> + if (!rc)
>> + *val = tmp & 0xff;
>> + else
>> + *val = 0xff;
>> +
>> + mctp_prdebug("%s 0x%hhx from %s (%d)",
>> + __func__, *val, reg ? "status" : "data", rc);
>> +
>> + return rc;
>> +}
>> +
>> +static int astlpc_kcs_reg_write(void *binding_data,
>> + enum mctp_binding_astlpc_kcs_reg reg,
>> + uint8_t val)
>> +{
>> + struct astlpc_ops_data *ops_data = binding_data;
>> + uint32_t addr;
>> +
>> + mctp_prdebug("%s 0x%hhx to %s",
>> + __func__, val, reg ? "status" : "data");
>> +
>> + if (reg == MCTP_ASTLPC_KCS_REG_STATUS)
>> + addr = ops_data->kcs_stat_addr;
>> + else if (reg == MCTP_ASTLPC_KCS_REG_DATA)
>> + addr = ops_data->kcs_data_addr;
>> + else
>> + return OPAL_PARAMETER;
>> +
>> + return lpc_write(OPAL_LPC_IO, addr, val, 1);
>> +}
>> +
>> +static int astlpc_read(void *binding_data, void *buf, long offset,
>> + size_t len)
>> +{
>> + struct astlpc_ops_data *ops_data = binding_data;
>> +
>> + mctp_prdebug("%s %zu bytes from 0x%lx (lpc: 0x%lx)",
>> + __func__, len, offset,
>> + ops_data->lpc_fw_addr + offset);
>> + return lpc_fw_read(ops_data->lpc_fw_addr + offset, buf, len);
>> +}
>> +
>> +static int astlpc_write(void *binding_data, const void *buf,
>> + long offset, size_t len)
>> +{
>> + struct astlpc_ops_data *ops_data = binding_data;
>> +
>> + mctp_prdebug("%s %zu bytes to offset 0x%lx (lpc: 0x%lx)",
>> + __func__, len, offset,
>> + ops_data->lpc_fw_addr + offset);
>> + return lpc_fw_write(ops_data->lpc_fw_addr + offset, buf, len);
>> +}
>> +
>> +static const struct mctp_binding_astlpc_ops astlpc_ops = {
>> + .kcs_read = astlpc_kcs_reg_read,
>> + .kcs_write = astlpc_kcs_reg_write,
>> + .lpc_read = astlpc_read,
>> + .lpc_write = astlpc_write,
>> +};
>> +
>> +static struct mctp_binding_astlpc *astlpc;
>> +static struct astlpc_ops_data *ops_data;
>> +
>> +/* Keyboard Controller Style (KCS) data register address */
>> +#define KCS_DATA_REG 0xca2
>> +
>> +/* Keyboard Controller Style (KCS) status register address */
>> +#define KCS_STATUS_REG 0xca3
>> +
>> +/* Serial IRQ number for KCS interface */
>> +#define KCS_SERIAL_IRQ 11
>
>
> These should probably be defined in platforms/astbmc/common.c and
> added to the device tree and the value read here from the device tree,
> like it's done for other LPC clients (UART, BT, MBOX).
>
ok will do.
>
>> +
>> +#define KCS_STATUS_BMC_READY 0x80
>> +
>> +bool irq_active;
>> +
>> +/* we need a poller to crank the mctp state machine during boot */
>> +static void astlpc_poller(struct timer *t __unused,
>> + void *data __unused, uint64_t now __unused)
>> +{
>> + mctp_astlpc_poll(astlpc);
>> +
>> + /* once booted we can rely on the KCS interrupt */
>> + if ((opal_booting() && !irq_active))
>
>
> We shoult talk about interrupts, I'm pretty convinced the call to
> opal_booting() is useless, since external interrupts are not going to
> fire while we are in skiboot. But this could all be moot if we use an
> opal poller (see below).
>
>
>> + schedule_timer(&ast_boot_timer, msecs_to_tb(5));
>> +}
>> +
>> +/* at runtime the interrupt should handle it */
>> +static void astlpc_interrupt(uint32_t chip_id __unused,
>> + uint32_t irq_msk __unused)
>> +{
>> + if (!irq_active) {
>> + mctp_prerr("IRQ Active! Disabling boot poller...");
>> + irq_active = true;
>> + }
>> +
>> + mctp_astlpc_poll(astlpc);
>> +}
>> +
>> +static struct lpc_client kcs_lpc_client = {
>> + .reset = NULL,
>> + .interrupt = astlpc_interrupt,
>> + .interrupts = LPC_IRQ(KCS_SERIAL_IRQ),
>> +};
>> +
>> +static bool astlpc_ready(void)
>> +{
>> + uint32_t tmp = 0;
>> +
>> + /* Probe for MCTP support by reading the STAT register of KCS#4 */
>> + if (lpc_probe_read(OPAL_LPC_IO, KCS_STATUS_REG, &tmp, 1)) {
>
>
> We've talked about this, I've done some reading and I don't understand
> the need for lpc_probe_read() here. My understanding is that the
> "probe" version is more forgiving in case of errors (it temporarily
> masks the interrupt, does a read, then checks the error status
> register to report errors) and it is meant to be used with invalid
> addresses for example. It's not the case here. I've been running with
> a simple lpc_read() and it's working as expected for me.
>
>
you have probably reason. We will use lpc_read() instead.
>> + mctp_prdebug("KCS4 probe failed, skipping MCTP init");
>> + return false;
>> + }
>> +
>> + return !!(tmp & KCS_STATUS_BMC_READY); /* high bit indicates BMC
>> is listening */
>> +}
>> +
>> +#define DESIRED_MTU 32768
>> +
>> +static void astlpc_destroy(void)
>> +{
>> + if (astlpc) {
>> + mctp_astlpc_destroy(astlpc);
>> + cancel_timer(&ast_boot_timer);
>> + astlpc = NULL;
>> + }
>> +}
>> +
>> +static int astlpc_binding(void)
>> +{
>> + ops_data = zalloc(sizeof(struct astlpc_ops_data));
>> + if (!ops_data)
>> + return OPAL_NO_MEM;
>> +
>> + /*
>> + * Current OpenBMC systems put the MCTP buffer 1MB down from
>> + * the end of the LPC FW range.
>> + *
>> + * The size of the FW range is: 0x1000_0000 so the window be at:
>> + *
>> + * 0x1000_0000 - 2**20 == 0xff00000
>> + */
>> + ops_data->lpc_fw_addr = 0xff00000;
>
>
> The fw address is already defined in HDAT! Look for "mctp_base" in
> bmc_create_node(). Maybe it could be added to the device tree from
> HDAT and read here?
>
>
Thanks.
>> +
>> + /* values chosen by the OpenBMC driver */
>> + ops_data->kcs_data_addr = KCS_DATA_REG;
>> + ops_data->kcs_stat_addr = KCS_STATUS_REG;
>> +
>> + /* Initialise the binding */
>> + astlpc = mctp_astlpc_init(MCTP_BINDING_ASTLPC_MODE_HOST,
>> + DESIRED_MTU,
>> + NULL,
>> + &astlpc_ops,
>> + ops_data);
>> + if (!astlpc) {
>> + mctp_prerr("binding init failed");
>> + return OPAL_HARDWARE;
>> + }
>> +
>> + /* register an lpc client so we get an interrupt */
>> + lpc_register_client(0, &kcs_lpc_client, IRQ_ATTR_TARGET_OPAL);
>> +
>> + init_timer(&ast_boot_timer, astlpc_poller, astlpc);
>> + schedule_timer(&ast_boot_timer, msecs_to_tb(5));
>
>
> I'm thinking we should convert this to an opal poller (by calling
> opal_add_poller()) instead of defining our own timer. It would call
> our polling function whenever opal_run_pollers() is called and we
> don't need to manage the timer (by re-arming it each time
> astlpc_poller() is called).
>
>
>> +
>> + /* Register the binding to the LPC bus we are using for this
>> + * MCTP configuration.
>> + */
>> + if (mctp_register_bus(mctp,
>> + mctp_binding_astlpc_core(astlpc),
>> + HOST_EID)) {
>> + mctp_prerr("failed to register bus");
>> + goto err;
>> + }
>> +
>> + return OPAL_SUCCESS;
>> +
>> +err:
>
>
> The timer needs to be cleaned up on the error path.
>
Good catch!
>
>> + astlpc_destroy();
>> + free(ops_data);
>> +
>> + return OPAL_HARDWARE;
>> +}
>> +
>> +static const struct ast_mctp_backend astlpc_backend = {
>> + .ready = astlpc_ready,
>> + .binding = astlpc_binding,
>> + .destroy = astlpc_destroy,
>> +};
>> +
>> +static void *mctp_malloc(size_t size) { return malloc(size); }
>> +static void mctp_free(void *ptr) { return free(ptr); }
>> +static void *mctp_realloc(void *ptr, size_t size)
>> +{
>> + return realloc(ptr, size);
>> +}
>> +
>> +#ifdef AST_MCTP_DEBUG
>> +char buffer[320];
>> +static void mctp_log(int log_lvl, const char *fmt, va_list va)
>> +{
>> + snprintf(buffer, sizeof(buffer), "%s\n", fmt);
>> + vprlog(log_lvl, buffer, va);
>> +}
>> +#endif
>
>
> I don't really like how logging is done in this file. We always reuse
> the libmctp trace macro, which means:
> - if we don't define AST_MCTP_DEBUG, we get no traces at all, not even
> errors.
> - if we define AST_MCTP_DEBUG, then we also get the traces from
> libmctp, which floods the in-memory skiboot trace buffer with traces
> such as:
> [ 371.500175890,7] AST-MCTP: astlpc_kcs_reg_read 0xc0 from status (0)
> [ 371.500219079,7] astlpc: host: mctp_astlpc_poll: status: 0xc0
>
> Why not use the usual prlog() for traces from this file?
> We can keep AST_MCTP_DEBUG just as a mean to control the libmctp
> tracing only.
>
ast-mctp.c is intrinsically linked to libmctp. For this reason we used
the same way of tracing.
But no problem to use prolog.
>
>> +
>> +int ast_mctp_ready(void)
>> +{
>> + if (!mctp_backend->ready())
>
>
> That's an exported API, so it would be better to check if mctp_backend
> and mctp_backend->ready are non-NULL before calling it.
>
Correct.
>
>> + return OPAL_BUSY;
>> +
>> + return OPAL_SUCCESS;
>> +}
>> +
>> +int ast_mctp_message_tx(uint8_t eid, uint8_t *msg, int len)
>> +{
>> + uint8_t tag = 0;
>> +
>> + return mctp_message_tx(mctp, eid, MCTP_MESSAGE_TO_DST, tag, msg,
>> len);
>> +}
>> +
>> +void ast_mctp_stop_polling(void)
>> +{
>
>
> This function looks like dead code. Leftover from debug?
>
Certainly, yes !
>
>> + irq_active = true;
>> +}
>> +
>> +#define HOST_MAX_INCOMING_MESSAGE_ALLOCATION 131072
>> +
>> +/*
>> + * Initialize mctp binding for hbrt and provide interfaces for sending
>> + * and receiving mctp messages.
>> + */
>> +int ast_mctp_init(uint8_t mode, void (*fn)(uint8_t src_eid, bool
>> tag_owner,
>> + uint8_t msg_tag, void *data, void *msg, size_t len))
>> +{
>> + uint64_t start;
>> +
>> + if (mode == MCTP_BINDING_ASTLPC_MODE)
>> + mctp_backend = &astlpc_backend;
>> + else {
>> + mctp_prerr("Unknown AST binding mode: %u", mode);
>> + return OPAL_PARAMETER;
>> + }
>> +
>> + if (!mctp_backend->ready())
>> + return OPAL_HARDWARE;
>> +
>> + /* skiboot's malloc/free/realloc are macros so they need
>> + * wrappers
>> + */
>> + mctp_set_alloc_ops(mctp_malloc, mctp_free, mctp_realloc);
>> +
>> + /*
>> + * /-----\ /---------\
>> + * | bmc | (eid: 8) <- lpc/kcs -> (eid: 9) | skiboot |
>> + * \-----/ pcie \---------/
>> + * astlpc kcs / astpcie binding
>> + */
>> + mctp = mctp_init();
>> + if (!mctp) {
>> + mctp_prerr("mctp init failed");
>> + return OPAL_HARDWARE;
>> + }
>> +
>> +#ifdef AST_MCTP_DEBUG
>> + /* Setup the trace hook */
>> + mctp_set_log_custom(mctp_log);
>> +#endif
>> +
>> + mctp_prinfo("libmctp initialized");
>> +
>> + /* Set the max message size to be large enough */
>> + mctp_set_max_message_size(mctp,
>> HOST_MAX_INCOMING_MESSAGE_ALLOCATION);
>> +
>> + /* Setup the message rx callback */
>> + mctp_set_rx_all(mctp, fn, NULL);
>> +
>> + /* Initialise the binding */
>> + if (mctp_backend->binding())
>> + goto err;
>> +
>> + /* Initializing the channel requires running the poll function
>> + * a few times to handle the initial setup since we need the
>> + * BMC to reply.
>> + *
>> + * Unfortuntately there's no good way to determine if this
>> + * worked or not so poll for a bit with a timeout. :(
>> + *
>> + * We have to check (bus->state == mctp_bus_state_constructed)
>> + * otherwise mctp_message_tx() will reject the message.
>> + */
>> + start = mftb();
>> + while (tb_compare(mftb(), start + msecs_to_tb(250)) == TB_ABEFOREB)
>> + time_wait_ms(10);
>
>
> Why not a simple time_wait_ms() for the full duration? It would call
> the opal_run_pollers(), which check the timers.
>
> Fred
>
>
>
>> +
>> + mctp_prwarn("%s - The mctp bus state should be correct now !!!",
>> + __func__);
>> +
>> + return OPAL_SUCCESS;
>> +
>> +err:
>> + mctp_prerr("Unable to initialize MCTP");
>> + mctp_destroy(mctp);
>> + mctp = NULL;
>> +
>> + return OPAL_HARDWARE;
>> +}
>> +
>> +void ast_mctp_exit(void)
>> +{
>> + if (mctp_backend && mctp_backend->destroy)
>> + mctp_backend->destroy();
>> +
>> + if (mctp)
>> + mctp_destroy(mctp);
>> +
>> + mctp = NULL;
>> +}
>> diff --git a/include/ast.h b/include/ast.h
>> index 5e932398..55eeae28 100644
>> --- a/include/ast.h
>> +++ b/include/ast.h
>> @@ -91,6 +91,17 @@ void ast_setup_ibt(uint16_t io_base, uint8_t irq);
>> /* MBOX configuration */
>> void ast_setup_sio_mbox(uint16_t io_base, uint8_t irq);
>> +/* AST MCTP configuration */
>> +#define MCTP_BINDING_ASTLPC_MODE 0
>> +#define MCTP_BINDING_ASTPCIE_MODE 1
>> +
>> +int ast_mctp_ready(void);
>> +int ast_mctp_init(uint8_t mode, void (*fn)(uint8_t src_eid, bool
>> tag_owner,
>> + uint8_t msg_tag, void *data, void *msg, size_t len));
>> +void ast_mctp_exit(void);
>> +void ast_mctp_stop_polling(void);
>> +int ast_mctp_message_tx(uint8_t eid, uint8_t *msg, int len);
>> +
>> #endif /* __SKIBOOT__ */
>> /*
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