diff options
| -rw-r--r-- | drivers/acpi/ec.c | 137 |
1 files changed, 132 insertions, 5 deletions
diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index 824f3e85023e..41eb523fa7ef 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -59,6 +59,38 @@ #define ACPI_EC_FLAG_BURST 0x10 /* burst mode */ #define ACPI_EC_FLAG_SCI 0x20 /* EC-SCI occurred */ +/* + * The SCI_EVT clearing timing is not defined by the ACPI specification. + * This leads to lots of practical timing issues for the host EC driver. + * The following variations are defined (from the target EC firmware's + * perspective): + * STATUS: After indicating SCI_EVT edge triggered IRQ to the host, the + * target can clear SCI_EVT at any time so long as the host can see + * the indication by reading the status register (EC_SC). So the + * host should re-check SCI_EVT after the first time the SCI_EVT + * indication is seen, which is the same time the query request + * (QR_EC) is written to the command register (EC_CMD). SCI_EVT set + * at any later time could indicate another event. Normally such + * kind of EC firmware has implemented an event queue and will + * return 0x00 to indicate "no outstanding event". + * QUERY: After seeing the query request (QR_EC) written to the command + * register (EC_CMD) by the host and having prepared the responding + * event value in the data register (EC_DATA), the target can safely + * clear SCI_EVT because the target can confirm that the current + * event is being handled by the host. The host then should check + * SCI_EVT right after reading the event response from the data + * register (EC_DATA). + * EVENT: After seeing the event response read from the data register + * (EC_DATA) by the host, the target can clear SCI_EVT. As the + * target requires time to notice the change in the data register + * (EC_DATA), the host may be required to wait additional guarding + * time before checking the SCI_EVT again. Such guarding may not be + * necessary if the host is notified via another IRQ. + */ +#define ACPI_EC_EVT_TIMING_STATUS 0x00 +#define ACPI_EC_EVT_TIMING_QUERY 0x01 +#define ACPI_EC_EVT_TIMING_EVENT 0x02 + /* EC commands */ enum ec_command { ACPI_EC_COMMAND_READ = 0x80, @@ -76,6 +108,7 @@ enum ec_command { enum { EC_FLAGS_QUERY_PENDING, /* Query is pending */ + EC_FLAGS_QUERY_GUARDING, /* Guard for SCI_EVT check */ EC_FLAGS_HANDLERS_INSTALLED, /* Handlers for GPE and * OpReg are installed */ EC_FLAGS_STARTED, /* Driver is started */ @@ -100,6 +133,8 @@ static unsigned int ec_polling_guard __read_mostly = ACPI_EC_UDELAY_POLL; module_param(ec_polling_guard, uint, 0644); MODULE_PARM_DESC(ec_polling_guard, "Guard time(us) between EC accesses in polling modes"); +static unsigned int ec_event_clearing __read_mostly = ACPI_EC_EVT_TIMING_STATUS; + /* * If the number of false interrupts per one transaction exceeds * this threshold, will think there is a GPE storm happened and @@ -400,6 +435,21 @@ static void acpi_ec_complete_query(struct acpi_ec *ec) } } +static bool acpi_ec_guard_event(struct acpi_ec *ec) +{ + if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS || + ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY || + !test_bit(EC_FLAGS_QUERY_PENDING, &ec->flags) || + (ec->curr && ec->curr->command == ACPI_EC_COMMAND_QUERY)) + return false; + + /* + * Postpone the query submission to allow the firmware to proceed, + * we shouldn't check SCI_EVT before the firmware reflagging it. + */ + return true; +} + static int ec_transaction_polled(struct acpi_ec *ec) { unsigned long flags; @@ -428,8 +478,15 @@ static inline void ec_transaction_transition(struct acpi_ec *ec, unsigned long f { ec->curr->flags |= flag; if (ec->curr->command == ACPI_EC_COMMAND_QUERY) { - if (flag == ACPI_EC_COMMAND_POLL) + if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS && + flag == ACPI_EC_COMMAND_POLL) + acpi_ec_complete_query(ec); + if (ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY && + flag == ACPI_EC_COMMAND_COMPLETE) acpi_ec_complete_query(ec); + if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT && + flag == ACPI_EC_COMMAND_COMPLETE) + set_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags); } } @@ -449,6 +506,17 @@ static void advance_transaction(struct acpi_ec *ec) acpi_ec_clear_gpe(ec); status = acpi_ec_read_status(ec); t = ec->curr; + /* + * Another IRQ or a guarded polling mode advancement is detected, + * the next QR_EC submission is then allowed. + */ + if (!t || !(t->flags & ACPI_EC_COMMAND_POLL)) { + if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT && + test_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags)) { + clear_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags); + acpi_ec_complete_query(ec); + } + } if (!t) goto err; if (t->flags & ACPI_EC_COMMAND_POLL) { @@ -534,11 +602,13 @@ static int ec_guard(struct acpi_ec *ec) /* * Perform wait polling * - * The following check is there to keep the old - * logic - no inter-transaction guarding for the - * wait polling mode. + * For SCI_EVT clearing timing of "event", + * performing guarding before re-checking the + * SCI_EVT. Otherwise, such guarding is not needed + * due to the old practices. */ - if (!ec_transaction_polled(ec)) + if (!ec_transaction_polled(ec) && + !acpi_ec_guard_event(ec)) break; if (wait_event_timeout(ec->wait, ec_transaction_completed(ec), @@ -964,6 +1034,24 @@ static int acpi_ec_query(struct acpi_ec *ec, u8 *data) return result; } +static void acpi_ec_check_event(struct acpi_ec *ec) +{ + unsigned long flags; + + if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT) { + if (ec_guard(ec)) { + spin_lock_irqsave(&ec->lock, flags); + /* + * Take care of the SCI_EVT unless no one else is + * taking care of it. + */ + if (!ec->curr) + advance_transaction(ec); + spin_unlock_irqrestore(&ec->lock, flags); + } + } +} + static void acpi_ec_event_handler(struct work_struct *work) { unsigned long flags; @@ -981,6 +1069,8 @@ static void acpi_ec_event_handler(struct work_struct *work) spin_unlock_irqrestore(&ec->lock, flags); ec_dbg_evt("Event stopped"); + + acpi_ec_check_event(ec); } static u32 acpi_ec_gpe_handler(acpi_handle gpe_device, @@ -1437,6 +1527,43 @@ error: return -ENODEV; } +static int param_set_event_clearing(const char *val, struct kernel_param *kp) +{ + int result = 0; + + if (!strncmp(val, "status", sizeof("status") - 1)) { + ec_event_clearing = ACPI_EC_EVT_TIMING_STATUS; + pr_info("Assuming SCI_EVT clearing on EC_SC accesses\n"); + } else if (!strncmp(val, "query", sizeof("query") - 1)) { + ec_event_clearing = ACPI_EC_EVT_TIMING_QUERY; + pr_info("Assuming SCI_EVT clearing on QR_EC writes\n"); + } else if (!strncmp(val, "event", sizeof("event") - 1)) { + ec_event_clearing = ACPI_EC_EVT_TIMING_EVENT; + pr_info("Assuming SCI_EVT clearing on event reads\n"); + } else + result = -EINVAL; + return result; +} + +static int param_get_event_clearing(char *buffer, struct kernel_param *kp) +{ + switch (ec_event_clearing) { + case ACPI_EC_EVT_TIMING_STATUS: + return sprintf(buffer, "status"); + case ACPI_EC_EVT_TIMING_QUERY: + return sprintf(buffer, "query"); + case ACPI_EC_EVT_TIMING_EVENT: + return sprintf(buffer, "event"); + default: + return sprintf(buffer, "invalid"); + } + return 0; +} + +module_param_call(ec_event_clearing, param_set_event_clearing, param_get_event_clearing, + NULL, 0644); +MODULE_PARM_DESC(ec_event_clearing, "Assumed SCI_EVT clearing timing"); + static struct acpi_driver acpi_ec_driver = { .name = "ec", .class = ACPI_EC_CLASS, |