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    Subject[PATCH 42/85] ACPI: EC: do transaction from interrupt context
    From: Alexey Starikovskiy <astarikovskiy@suse.de>

    It is easier and faster to do transaction directly from interrupt context
    rather than waking control thread.
    Also, cleaner GPE storm avoidance is implemented.
    References: http://bugzilla.kernel.org/show_bug.cgi?id=9998
    http://bugzilla.kernel.org/show_bug.cgi?id=10724
    http://bugzilla.kernel.org/show_bug.cgi?id=10919
    http://bugzilla.kernel.org/show_bug.cgi?id=11309
    http://bugzilla.kernel.org/show_bug.cgi?id=11549
    Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
    Tested-by: Sitsofe Wheeler <sitsofe@yahoo.com>
    Signed-off-by: Len Brown <len.brown@intel.com>
    ---
    drivers/acpi/ec.c | 309 +++++++++++++++++++++++++---------------------------
    1 files changed, 149 insertions(+), 160 deletions(-)

    diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
    index 13593f9..7f0d81c 100644
    --- a/drivers/acpi/ec.c
    +++ b/drivers/acpi/ec.c
    @@ -1,7 +1,7 @@
    /*
    - * ec.c - ACPI Embedded Controller Driver (v2.0)
    + * ec.c - ACPI Embedded Controller Driver (v2.1)
    *
    - * Copyright (C) 2006, 2007 Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
    + * Copyright (C) 2006-2008 Alexey Starikovskiy <astarikovskiy@suse.de>
    * Copyright (C) 2006 Denis Sadykov <denis.m.sadykov@intel.com>
    * Copyright (C) 2004 Luming Yu <luming.yu@intel.com>
    * Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
    @@ -26,7 +26,7 @@
    * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    */

    -/* Uncomment next line to get verbose print outs*/
    +/* Uncomment next line to get verbose printout */
    /* #define DEBUG */

    #include <linux/kernel.h>
    @@ -38,6 +38,7 @@
    #include <linux/seq_file.h>
    #include <linux/interrupt.h>
    #include <linux/list.h>
    +#include <linux/spinlock.h>
    #include <asm/io.h>
    #include <acpi/acpi_bus.h>
    #include <acpi/acpi_drivers.h>
    @@ -65,22 +66,21 @@ enum ec_command {
    ACPI_EC_COMMAND_QUERY = 0x84,
    };

    -/* EC events */
    -enum ec_event {
    - ACPI_EC_EVENT_OBF_1 = 1, /* Output buffer full */
    - ACPI_EC_EVENT_IBF_0, /* Input buffer empty */
    -};
    -
    #define ACPI_EC_DELAY 500 /* Wait 500ms max. during EC ops */
    #define ACPI_EC_UDELAY_GLK 1000 /* Wait 1ms max. to get global lock */
    #define ACPI_EC_UDELAY 100 /* Wait 100us before polling EC again */

    +#define ACPI_EC_STORM_THRESHOLD 20 /* number of false interrupts
    + per one transaction */
    +
    enum {
    - EC_FLAGS_WAIT_GPE = 0, /* Don't check status until GPE arrives */
    EC_FLAGS_QUERY_PENDING, /* Query is pending */
    - EC_FLAGS_GPE_MODE, /* Expect GPE to be sent for status change */
    + EC_FLAGS_GPE_MODE, /* Expect GPE to be sent
    + * for status change */
    EC_FLAGS_NO_GPE, /* Don't use GPE mode */
    - EC_FLAGS_RESCHEDULE_POLL /* Re-schedule poll */
    + EC_FLAGS_GPE_STORM, /* GPE storm detected */
    + EC_FLAGS_HANDLERS_INSTALLED /* Handlers for GPE and
    + * OpReg are installed */
    };

    /* If we find an EC via the ECDT, we need to keep a ptr to its context */
    @@ -95,6 +95,14 @@ struct acpi_ec_query_handler {
    u8 query_bit;
    };

    +struct transaction_data {
    + const u8 *wdata;
    + u8 *rdata;
    + unsigned short irq_count;
    + u8 wlen;
    + u8 rlen;
    +};
    +
    static struct acpi_ec {
    acpi_handle handle;
    unsigned long gpe;
    @@ -105,9 +113,8 @@ static struct acpi_ec {
    struct mutex lock;
    wait_queue_head_t wait;
    struct list_head list;
    - struct delayed_work work;
    - atomic_t irq_count;
    - u8 handlers_installed;
    + struct transaction_data *t;
    + spinlock_t t_lock;
    } *boot_ec, *first_ec;

    /*
    @@ -150,7 +157,7 @@ static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
    {
    u8 x = inb(ec->data_addr);
    pr_debug(PREFIX "---> data = 0x%2.2x\n", x);
    - return inb(ec->data_addr);
    + return x;
    }

    static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command)
    @@ -165,68 +172,79 @@ static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
    outb(data, ec->data_addr);
    }

    -static inline int acpi_ec_check_status(struct acpi_ec *ec, enum ec_event event)
    +static int ec_transaction_done(struct acpi_ec *ec)
    {
    - if (test_bit(EC_FLAGS_WAIT_GPE, &ec->flags))
    - return 0;
    - if (event == ACPI_EC_EVENT_OBF_1) {
    - if (acpi_ec_read_status(ec) & ACPI_EC_FLAG_OBF)
    - return 1;
    - } else if (event == ACPI_EC_EVENT_IBF_0) {
    - if (!(acpi_ec_read_status(ec) & ACPI_EC_FLAG_IBF))
    - return 1;
    - }
    -
    - return 0;
    + unsigned long flags;
    + int ret = 0;
    + spin_lock_irqsave(&ec->t_lock, flags);
    + if (!ec->t || (!ec->t->wlen && !ec->t->rlen))
    + ret = 1;
    + spin_unlock_irqrestore(&ec->t_lock, flags);
    + return ret;
    }

    -static void ec_schedule_ec_poll(struct acpi_ec *ec)
    +static void gpe_transaction(struct acpi_ec *ec, u8 status)
    {
    - if (test_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags))
    - schedule_delayed_work(&ec->work,
    - msecs_to_jiffies(ACPI_EC_DELAY));
    + unsigned long flags;
    + spin_lock_irqsave(&ec->t_lock, flags);
    + if (!ec->t)
    + goto unlock;
    + if (ec->t->wlen > 0) {
    + if ((status & ACPI_EC_FLAG_IBF) == 0) {
    + acpi_ec_write_data(ec, *(ec->t->wdata++));
    + --ec->t->wlen;
    + } else
    + /* false interrupt, state didn't change */
    + ++ec->t->irq_count;
    +
    + } else if (ec->t->rlen > 0) {
    + if ((status & ACPI_EC_FLAG_OBF) == 1) {
    + *(ec->t->rdata++) = acpi_ec_read_data(ec);
    + --ec->t->rlen;
    + } else
    + /* false interrupt, state didn't change */
    + ++ec->t->irq_count;
    + }
    +unlock:
    + spin_unlock_irqrestore(&ec->t_lock, flags);
    }

    -static void ec_switch_to_poll_mode(struct acpi_ec *ec)
    +static int acpi_ec_wait(struct acpi_ec *ec)
    {
    + if (wait_event_timeout(ec->wait, ec_transaction_done(ec),
    + msecs_to_jiffies(ACPI_EC_DELAY)))
    + return 0;
    + /* missing GPEs, switch back to poll mode */
    + if (printk_ratelimit())
    + pr_info(PREFIX "missing confirmations, "
    + "switch off interrupt mode.\n");
    set_bit(EC_FLAGS_NO_GPE, &ec->flags);
    clear_bit(EC_FLAGS_GPE_MODE, &ec->flags);
    - acpi_disable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
    - set_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags);
    + return 1;
    }

    -static int acpi_ec_wait(struct acpi_ec *ec, enum ec_event event, int force_poll)
    +static void acpi_ec_gpe_query(void *ec_cxt);
    +
    +static int ec_check_sci(struct acpi_ec *ec, u8 state)
    {
    - atomic_set(&ec->irq_count, 0);
    - if (likely(test_bit(EC_FLAGS_GPE_MODE, &ec->flags)) &&
    - likely(!force_poll)) {
    - if (wait_event_timeout(ec->wait, acpi_ec_check_status(ec, event),
    - msecs_to_jiffies(ACPI_EC_DELAY)))
    - return 0;
    - clear_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
    - if (acpi_ec_check_status(ec, event)) {
    - /* missing GPEs, switch back to poll mode */
    - if (printk_ratelimit())
    - pr_info(PREFIX "missing confirmations, "
    - "switch off interrupt mode.\n");
    - ec_switch_to_poll_mode(ec);
    - ec_schedule_ec_poll(ec);
    - return 0;
    - }
    - } else {
    - unsigned long delay = jiffies + msecs_to_jiffies(ACPI_EC_DELAY);
    - clear_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
    - while (time_before(jiffies, delay)) {
    - if (acpi_ec_check_status(ec, event))
    - return 0;
    - msleep(1);
    - }
    - if (acpi_ec_check_status(ec,event))
    + if (state & ACPI_EC_FLAG_SCI) {
    + if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags))
    + return acpi_os_execute(OSL_EC_BURST_HANDLER,
    + acpi_ec_gpe_query, ec);
    + }
    + return 0;
    +}
    +
    +static int ec_poll(struct acpi_ec *ec)
    +{
    + unsigned long delay = jiffies + msecs_to_jiffies(ACPI_EC_DELAY);
    + msleep(1);
    + while (time_before(jiffies, delay)) {
    + gpe_transaction(ec, acpi_ec_read_status(ec));
    + msleep(1);
    + if (ec_transaction_done(ec))
    return 0;
    }
    - pr_err(PREFIX "acpi_ec_wait timeout, status = 0x%2.2x, event = %s\n",
    - acpi_ec_read_status(ec),
    - (event == ACPI_EC_EVENT_OBF_1) ? "\"b0=1\"" : "\"b1=0\"");
    return -ETIME;
    }

    @@ -235,45 +253,51 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, u8 command,
    u8 * rdata, unsigned rdata_len,
    int force_poll)
    {
    - int result = 0;
    - set_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
    + unsigned long tmp;
    + struct transaction_data t = {.wdata = wdata, .rdata = rdata,
    + .wlen = wdata_len, .rlen = rdata_len,
    + .irq_count = 0};
    + int ret = 0;
    pr_debug(PREFIX "transaction start\n");
    - acpi_ec_write_cmd(ec, command);
    - for (; wdata_len > 0; --wdata_len) {
    - result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, force_poll);
    - if (result) {
    - pr_err(PREFIX
    - "write_cmd timeout, command = %d\n", command);
    - goto end;
    - }
    - set_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
    - acpi_ec_write_data(ec, *(wdata++));
    + /* disable GPE during transaction if storm is detected */
    + if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
    + clear_bit(EC_FLAGS_GPE_MODE, &ec->flags);
    + acpi_disable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
    }
    -
    - if (!rdata_len) {
    - result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, force_poll);
    - if (result) {
    - pr_err(PREFIX
    - "finish-write timeout, command = %d\n", command);
    - goto end;
    - }
    - } else if (command == ACPI_EC_COMMAND_QUERY)
    + /* start transaction */
    + spin_lock_irqsave(&ec->t_lock, tmp);
    + /* following two actions should be kept atomic */
    + ec->t = &t;
    + acpi_ec_write_cmd(ec, command);
    + if (command == ACPI_EC_COMMAND_QUERY)
    clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
    -
    - for (; rdata_len > 0; --rdata_len) {
    - result = acpi_ec_wait(ec, ACPI_EC_EVENT_OBF_1, force_poll);
    - if (result) {
    - pr_err(PREFIX "read timeout, command = %d\n", command);
    - goto end;
    - }
    - /* Don't expect GPE after last read */
    - if (rdata_len > 1)
    - set_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
    - *(rdata++) = acpi_ec_read_data(ec);
    - }
    - end:
    + spin_unlock_irqrestore(&ec->t_lock, tmp);
    + /* if we selected poll mode or failed in GPE-mode do a poll loop */
    + if (force_poll ||
    + !test_bit(EC_FLAGS_GPE_MODE, &ec->flags) ||
    + acpi_ec_wait(ec))
    + ret = ec_poll(ec);
    pr_debug(PREFIX "transaction end\n");
    - return result;
    + spin_lock_irqsave(&ec->t_lock, tmp);
    + ec->t = NULL;
    + spin_unlock_irqrestore(&ec->t_lock, tmp);
    + if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
    + /* check if we received SCI during transaction */
    + ec_check_sci(ec, acpi_ec_read_status(ec));
    + /* it is safe to enable GPE outside of transaction */
    + acpi_enable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
    + } else if (test_bit(EC_FLAGS_GPE_MODE, &ec->flags) &&
    + t.irq_count > ACPI_EC_STORM_THRESHOLD) {
    + pr_debug(PREFIX "GPE storm detected\n");
    + set_bit(EC_FLAGS_GPE_STORM, &ec->flags);
    + }
    + return ret;
    +}
    +
    +static int ec_check_ibf0(struct acpi_ec *ec)
    +{
    + u8 status = acpi_ec_read_status(ec);
    + return (status & ACPI_EC_FLAG_IBF) == 0;
    }

    static int acpi_ec_transaction(struct acpi_ec *ec, u8 command,
    @@ -283,40 +307,34 @@ static int acpi_ec_transaction(struct acpi_ec *ec, u8 command,
    {
    int status;
    u32 glk;
    -
    if (!ec || (wdata_len && !wdata) || (rdata_len && !rdata))
    return -EINVAL;
    -
    if (rdata)
    memset(rdata, 0, rdata_len);
    -
    mutex_lock(&ec->lock);
    if (ec->global_lock) {
    status = acpi_acquire_global_lock(ACPI_EC_UDELAY_GLK, &glk);
    if (ACPI_FAILURE(status)) {
    - mutex_unlock(&ec->lock);
    - return -ENODEV;
    + status = -ENODEV;
    + goto unlock;
    }
    }
    -
    - status = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, 0);
    - if (status) {
    + if (!wait_event_timeout(ec->wait, ec_check_ibf0(ec),
    + msecs_to_jiffies(ACPI_EC_DELAY))) {
    pr_err(PREFIX "input buffer is not empty, "
    "aborting transaction\n");
    + status = -ETIME;
    goto end;
    }
    -
    status = acpi_ec_transaction_unlocked(ec, command,
    wdata, wdata_len,
    rdata, rdata_len,
    force_poll);
    -
    - end:
    -
    +end:
    if (ec->global_lock)
    acpi_release_global_lock(glk);
    +unlock:
    mutex_unlock(&ec->lock);
    -
    return status;
    }

    @@ -332,7 +350,9 @@ int acpi_ec_burst_enable(struct acpi_ec *ec)

    int acpi_ec_burst_disable(struct acpi_ec *ec)
    {
    - return acpi_ec_transaction(ec, ACPI_EC_BURST_DISABLE, NULL, 0, NULL, 0, 0);
    + return (acpi_ec_read_status(ec) & ACPI_EC_FLAG_BURST) ?
    + acpi_ec_transaction(ec, ACPI_EC_BURST_DISABLE,
    + NULL, 0, NULL, 0, 0) : 0;
    }

    static int acpi_ec_read(struct acpi_ec *ec, u8 address, u8 * data)
    @@ -513,46 +533,26 @@ static void acpi_ec_gpe_query(void *ec_cxt)

    static u32 acpi_ec_gpe_handler(void *data)
    {
    - acpi_status status = AE_OK;
    struct acpi_ec *ec = data;
    - u8 state = acpi_ec_read_status(ec);
    + u8 status;

    pr_debug(PREFIX "~~~> interrupt\n");
    - atomic_inc(&ec->irq_count);
    - if (atomic_read(&ec->irq_count) > 5) {
    - pr_err(PREFIX "GPE storm detected, disabling EC GPE\n");
    - ec_switch_to_poll_mode(ec);
    - goto end;
    - }
    - clear_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
    - if (test_bit(EC_FLAGS_GPE_MODE, &ec->flags))
    + status = acpi_ec_read_status(ec);
    +
    + gpe_transaction(ec, status);
    + if (ec_transaction_done(ec) && (status & ACPI_EC_FLAG_IBF) == 0)
    wake_up(&ec->wait);

    - if (state & ACPI_EC_FLAG_SCI) {
    - if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags))
    - status = acpi_os_execute(OSL_EC_BURST_HANDLER,
    - acpi_ec_gpe_query, ec);
    - } else if (!test_bit(EC_FLAGS_GPE_MODE, &ec->flags) &&
    - !test_bit(EC_FLAGS_NO_GPE, &ec->flags) &&
    - in_interrupt()) {
    + ec_check_sci(ec, status);
    + if (!test_bit(EC_FLAGS_GPE_MODE, &ec->flags) &&
    + !test_bit(EC_FLAGS_NO_GPE, &ec->flags)) {
    /* this is non-query, must be confirmation */
    if (printk_ratelimit())
    pr_info(PREFIX "non-query interrupt received,"
    " switching to interrupt mode\n");
    set_bit(EC_FLAGS_GPE_MODE, &ec->flags);
    - clear_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags);
    }
    -end:
    - ec_schedule_ec_poll(ec);
    - return ACPI_SUCCESS(status) ?
    - ACPI_INTERRUPT_HANDLED : ACPI_INTERRUPT_NOT_HANDLED;
    -}
    -
    -static void do_ec_poll(struct work_struct *work)
    -{
    - struct acpi_ec *ec = container_of(work, struct acpi_ec, work.work);
    - atomic_set(&ec->irq_count, 0);
    - (void)acpi_ec_gpe_handler(ec);
    + return ACPI_INTERRUPT_HANDLED;
    }

    /* --------------------------------------------------------------------------
    @@ -696,8 +696,7 @@ static struct acpi_ec *make_acpi_ec(void)
    mutex_init(&ec->lock);
    init_waitqueue_head(&ec->wait);
    INIT_LIST_HEAD(&ec->list);
    - INIT_DELAYED_WORK_DEFERRABLE(&ec->work, do_ec_poll);
    - atomic_set(&ec->irq_count, 0);
    + spin_lock_init(&ec->t_lock);
    return ec;
    }

    @@ -736,22 +735,15 @@ ec_parse_device(acpi_handle handle, u32 Level, void *context, void **retval)
    return AE_CTRL_TERMINATE;
    }

    -static void ec_poll_stop(struct acpi_ec *ec)
    -{
    - clear_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags);
    - cancel_delayed_work(&ec->work);
    -}
    -
    static void ec_remove_handlers(struct acpi_ec *ec)
    {
    - ec_poll_stop(ec);
    if (ACPI_FAILURE(acpi_remove_address_space_handler(ec->handle,
    ACPI_ADR_SPACE_EC, &acpi_ec_space_handler)))
    pr_err(PREFIX "failed to remove space handler\n");
    if (ACPI_FAILURE(acpi_remove_gpe_handler(NULL, ec->gpe,
    &acpi_ec_gpe_handler)))
    pr_err(PREFIX "failed to remove gpe handler\n");
    - ec->handlers_installed = 0;
    + clear_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags);
    }

    static int acpi_ec_add(struct acpi_device *device)
    @@ -846,17 +838,15 @@ ec_parse_io_ports(struct acpi_resource *resource, void *context)
    static int ec_install_handlers(struct acpi_ec *ec)
    {
    acpi_status status;
    - if (ec->handlers_installed)
    + if (test_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags))
    return 0;
    status = acpi_install_gpe_handler(NULL, ec->gpe,
    - ACPI_GPE_EDGE_TRIGGERED,
    - &acpi_ec_gpe_handler, ec);
    + ACPI_GPE_EDGE_TRIGGERED,
    + &acpi_ec_gpe_handler, ec);
    if (ACPI_FAILURE(status))
    return -ENODEV;
    -
    acpi_set_gpe_type(NULL, ec->gpe, ACPI_GPE_TYPE_RUNTIME);
    acpi_enable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
    -
    status = acpi_install_address_space_handler(ec->handle,
    ACPI_ADR_SPACE_EC,
    &acpi_ec_space_handler,
    @@ -866,7 +856,7 @@ static int ec_install_handlers(struct acpi_ec *ec)
    return -ENODEV;
    }

    - ec->handlers_installed = 1;
    + set_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags);
    return 0;
    }

    @@ -887,7 +877,6 @@ static int acpi_ec_start(struct acpi_device *device)

    /* EC is fully operational, allow queries */
    clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
    - ec_schedule_ec_poll(ec);
    return ret;
    }

    @@ -906,7 +895,7 @@ static int acpi_ec_stop(struct acpi_device *device, int type)

    int __init acpi_boot_ec_enable(void)
    {
    - if (!boot_ec || boot_ec->handlers_installed)
    + if (!boot_ec || test_bit(EC_FLAGS_HANDLERS_INSTALLED, &boot_ec->flags))
    return 0;
    if (!ec_install_handlers(boot_ec)) {
    first_ec = boot_ec;
    --
    1.5.5.1


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