V4L/DVB (6715): ivtv: Remove unnecessary register update

[linux-2.6/verdex.git] / drivers / ata / libata-acpi.c

/*
 * libata-acpi.c
 * Provides ACPI support for PATA/SATA.
 *
 * Copyright (C) 2006 Intel Corp.
 * Copyright (C) 2006 Randy Dunlap
 */

#include <linux/module.h>
#include <linux/ata.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/acpi.h>
#include <linux/libata.h>
#include <linux/pci.h>
#include <scsi/scsi_device.h>
#include "libata.h"

#include <acpi/acpi_bus.h>
#include <acpi/acnames.h>
#include <acpi/acnamesp.h>
#include <acpi/acparser.h>
#include <acpi/acexcep.h>
#include <acpi/acmacros.h>
#include <acpi/actypes.h>

enum {
        ATA_ACPI_FILTER_SETXFER = 1 << 0,
        ATA_ACPI_FILTER_LOCK    = 1 << 1,

        ATA_ACPI_FILTER_DEFAULT = ATA_ACPI_FILTER_SETXFER |
                                  ATA_ACPI_FILTER_LOCK,
};

static unsigned int ata_acpi_gtf_filter = ATA_ACPI_FILTER_DEFAULT;
module_param_named(acpi_gtf_filter, ata_acpi_gtf_filter, int, 0644);
MODULE_PARM_DESC(acpi_gtf_filter, "filter mask for ACPI _GTF commands, set to filter out (0x1=set xfermode, 0x2=lock/freeze lock)");

#define NO_PORT_MULT            0xffff
#define SATA_ADR(root, pmp)     (((root) << 16) | (pmp))

#define REGS_PER_GTF            7
struct ata_acpi_gtf {
        u8      tf[REGS_PER_GTF];       /* regs. 0x1f1 - 0x1f7 */
} __packed;

/*
 *      Helper - belongs in the PCI layer somewhere eventually
 */
static int is_pci_dev(struct device *dev)
{
        return (dev->bus == &pci_bus_type);
}

static void ata_acpi_clear_gtf(struct ata_device *dev)
{
        kfree(dev->gtf_cache);
        dev->gtf_cache = NULL;
}

/**
 * ata_acpi_associate_sata_port - associate SATA port with ACPI objects
 * @ap: target SATA port
 *
 * Look up ACPI objects associated with @ap and initialize acpi_handle
 * fields of @ap, the port and devices accordingly.
 *
 * LOCKING:
 * EH context.
 *
 * RETURNS:
 * 0 on success, -errno on failure.
 */
void ata_acpi_associate_sata_port(struct ata_port *ap)
{
        WARN_ON(!(ap->flags & ATA_FLAG_ACPI_SATA));

        if (!ap->nr_pmp_links) {
                acpi_integer adr = SATA_ADR(ap->port_no, NO_PORT_MULT);

                ap->link.device->acpi_handle =
                        acpi_get_child(ap->host->acpi_handle, adr);
        } else {
                struct ata_link *link;

                ap->link.device->acpi_handle = NULL;

                ata_port_for_each_link(link, ap) {
                        acpi_integer adr = SATA_ADR(ap->port_no, link->pmp);

                        link->device->acpi_handle =
                                acpi_get_child(ap->host->acpi_handle, adr);
                }
        }
}

static void ata_acpi_associate_ide_port(struct ata_port *ap)
{
        int max_devices, i;

        ap->acpi_handle = acpi_get_child(ap->host->acpi_handle, ap->port_no);
        if (!ap->acpi_handle)
                return;

        max_devices = 1;
        if (ap->flags & ATA_FLAG_SLAVE_POSS)
                max_devices++;

        for (i = 0; i < max_devices; i++) {
                struct ata_device *dev = &ap->link.device[i];

                dev->acpi_handle = acpi_get_child(ap->acpi_handle, i);
        }

        if (ata_acpi_gtm(ap, &ap->__acpi_init_gtm) == 0)
                ap->pflags |= ATA_PFLAG_INIT_GTM_VALID;
}

static void ata_acpi_handle_hotplug(struct ata_port *ap, struct kobject *kobj,
                                    u32 event)
{
        char event_string[12];
        char *envp[] = { event_string, NULL };
        struct ata_eh_info *ehi = &ap->link.eh_info;

        if (event == 0 || event == 1) {
               unsigned long flags;
               spin_lock_irqsave(ap->lock, flags);
               ata_ehi_clear_desc(ehi);
               ata_ehi_push_desc(ehi, "ACPI event");
               ata_ehi_hotplugged(ehi);
               ata_port_freeze(ap);
               spin_unlock_irqrestore(ap->lock, flags);
        }

        if (kobj) {
                sprintf(event_string, "BAY_EVENT=%d", event);
                kobject_uevent_env(kobj, KOBJ_CHANGE, envp);
        }
}

static void ata_acpi_dev_notify(acpi_handle handle, u32 event, void *data)
{
        struct ata_device *dev = data;
        struct kobject *kobj = NULL;

        if (dev->sdev)
                kobj = &dev->sdev->sdev_gendev.kobj;

        ata_acpi_handle_hotplug(dev->link->ap, kobj, event);
}

static void ata_acpi_ap_notify(acpi_handle handle, u32 event, void *data)
{
        struct ata_port *ap = data;

        ata_acpi_handle_hotplug(ap, &ap->dev->kobj, event);
}

/**
 * ata_acpi_associate - associate ATA host with ACPI objects
 * @host: target ATA host
 *
 * Look up ACPI objects associated with @host and initialize
 * acpi_handle fields of @host, its ports and devices accordingly.
 *
 * LOCKING:
 * EH context.
 *
 * RETURNS:
 * 0 on success, -errno on failure.
 */
void ata_acpi_associate(struct ata_host *host)
{
        int i, j;

        if (!is_pci_dev(host->dev) || libata_noacpi)
                return;

        host->acpi_handle = DEVICE_ACPI_HANDLE(host->dev);
        if (!host->acpi_handle)
                return;

        for (i = 0; i < host->n_ports; i++) {
                struct ata_port *ap = host->ports[i];

                if (host->ports[0]->flags & ATA_FLAG_ACPI_SATA)
                        ata_acpi_associate_sata_port(ap);
                else
                        ata_acpi_associate_ide_port(ap);

                if (ap->acpi_handle)
                        acpi_install_notify_handler (ap->acpi_handle,
                                                     ACPI_SYSTEM_NOTIFY,
                                                     ata_acpi_ap_notify,
                                                     ap);

                for (j = 0; j < ata_link_max_devices(&ap->link); j++) {
                        struct ata_device *dev = &ap->link.device[j];

                        if (dev->acpi_handle)
                                acpi_install_notify_handler (dev->acpi_handle,
                                                             ACPI_SYSTEM_NOTIFY,
                                                             ata_acpi_dev_notify,
                                                             dev);
                }
        }
}

/**
 * ata_acpi_dissociate - dissociate ATA host from ACPI objects
 * @host: target ATA host
 *
 * This function is called during driver detach after the whole host
 * is shut down.
 *
 * LOCKING:
 * EH context.
 */
void ata_acpi_dissociate(struct ata_host *host)
{
        int i;

        /* Restore initial _GTM values so that driver which attaches
         * afterward can use them too.
         */
        for (i = 0; i < host->n_ports; i++) {
                struct ata_port *ap = host->ports[i];
                const struct ata_acpi_gtm *gtm = ata_acpi_init_gtm(ap);

                if (ap->acpi_handle && gtm)
                        ata_acpi_stm(ap, gtm);
        }
}

/**
 * ata_acpi_gtm - execute _GTM
 * @ap: target ATA port
 * @gtm: out parameter for _GTM result
 *
 * Evaluate _GTM and store the result in @gtm.
 *
 * LOCKING:
 * EH context.
 *
 * RETURNS:
 * 0 on success, -ENOENT if _GTM doesn't exist, -errno on failure.
 */
int ata_acpi_gtm(struct ata_port *ap, struct ata_acpi_gtm *gtm)
{
        struct acpi_buffer output = { .length = ACPI_ALLOCATE_BUFFER };
        union acpi_object *out_obj;
        acpi_status status;
        int rc = 0;

        status = acpi_evaluate_object(ap->acpi_handle, "_GTM", NULL, &output);

        rc = -ENOENT;
        if (status == AE_NOT_FOUND)
                goto out_free;

        rc = -EINVAL;
        if (ACPI_FAILURE(status)) {
                ata_port_printk(ap, KERN_ERR,
                                "ACPI get timing mode failed (AE 0x%x)\n",
                                status);
                goto out_free;
        }

        out_obj = output.pointer;
        if (out_obj->type != ACPI_TYPE_BUFFER) {
                ata_port_printk(ap, KERN_WARNING,
                                "_GTM returned unexpected object type 0x%x\n",
                                out_obj->type);

                goto out_free;
        }

        if (out_obj->buffer.length != sizeof(struct ata_acpi_gtm)) {
                ata_port_printk(ap, KERN_ERR,
                                "_GTM returned invalid length %d\n",
                                out_obj->buffer.length);
                goto out_free;
        }

        memcpy(gtm, out_obj->buffer.pointer, sizeof(struct ata_acpi_gtm));
        rc = 0;
 out_free:
        kfree(output.pointer);
        return rc;
}

EXPORT_SYMBOL_GPL(ata_acpi_gtm);

/**
 * ata_acpi_stm - execute _STM
 * @ap: target ATA port
 * @stm: timing parameter to _STM
 *
 * Evaluate _STM with timing parameter @stm.
 *
 * LOCKING:
 * EH context.
 *
 * RETURNS:
 * 0 on success, -ENOENT if _STM doesn't exist, -errno on failure.
 */
int ata_acpi_stm(struct ata_port *ap, const struct ata_acpi_gtm *stm)
{
        acpi_status status;
        struct ata_acpi_gtm             stm_buf = *stm;
        struct acpi_object_list         input;
        union acpi_object               in_params[3];

        in_params[0].type = ACPI_TYPE_BUFFER;
        in_params[0].buffer.length = sizeof(struct ata_acpi_gtm);
        in_params[0].buffer.pointer = (u8 *)&stm_buf;
        /* Buffers for id may need byteswapping ? */
        in_params[1].type = ACPI_TYPE_BUFFER;
        in_params[1].buffer.length = 512;
        in_params[1].buffer.pointer = (u8 *)ap->link.device[0].id;
        in_params[2].type = ACPI_TYPE_BUFFER;
        in_params[2].buffer.length = 512;
        in_params[2].buffer.pointer = (u8 *)ap->link.device[1].id;

        input.count = 3;
        input.pointer = in_params;

        status = acpi_evaluate_object(ap->acpi_handle, "_STM", &input, NULL);

        if (status == AE_NOT_FOUND)
                return -ENOENT;
        if (ACPI_FAILURE(status)) {
                ata_port_printk(ap, KERN_ERR,
                        "ACPI set timing mode failed (status=0x%x)\n", status);
                return -EINVAL;
        }
        return 0;
}

EXPORT_SYMBOL_GPL(ata_acpi_stm);

/**
 * ata_dev_get_GTF - get the drive bootup default taskfile settings
 * @dev: target ATA device
 * @gtf: output parameter for buffer containing _GTF taskfile arrays
 *
 * This applies to both PATA and SATA drives.
 *
 * The _GTF method has no input parameters.
 * It returns a variable number of register set values (registers
 * hex 1F1..1F7, taskfiles).
 * The <variable number> is not known in advance, so have ACPI-CA
 * allocate the buffer as needed and return it, then free it later.
 *
 * LOCKING:
 * EH context.
 *
 * RETURNS:
 * Number of taskfiles on success, 0 if _GTF doesn't exist.  -EINVAL
 * if _GTF is invalid.
 */
static int ata_dev_get_GTF(struct ata_device *dev, struct ata_acpi_gtf **gtf)
{
        struct ata_port *ap = dev->link->ap;
        acpi_status status;
        struct acpi_buffer output;
        union acpi_object *out_obj;
        int rc = 0;

        /* if _GTF is cached, use the cached value */
        if (dev->gtf_cache) {
                out_obj = dev->gtf_cache;
                goto done;
        }

        /* set up output buffer */
        output.length = ACPI_ALLOCATE_BUFFER;
        output.pointer = NULL;  /* ACPI-CA sets this; save/free it later */

        if (ata_msg_probe(ap))
                ata_dev_printk(dev, KERN_DEBUG, "%s: ENTER: port#: %d\n",
                               __FUNCTION__, ap->port_no);

        /* _GTF has no input parameters */
        status = acpi_evaluate_object(dev->acpi_handle, "_GTF", NULL, &output);
        out_obj = dev->gtf_cache = output.pointer;

        if (ACPI_FAILURE(status)) {
                if (status != AE_NOT_FOUND) {
                        ata_dev_printk(dev, KERN_WARNING,
                                       "_GTF evaluation failed (AE 0x%x)\n",
                                       status);
                        rc = -EINVAL;
                }
                goto out_free;
        }

        if (!output.length || !output.pointer) {
                if (ata_msg_probe(ap))
                        ata_dev_printk(dev, KERN_DEBUG, "%s: Run _GTF: "
                                "length or ptr is NULL (0x%llx, 0x%p)\n",
                                __FUNCTION__,
                                (unsigned long long)output.length,
                                output.pointer);
                rc = -EINVAL;
                goto out_free;
        }

        if (out_obj->type != ACPI_TYPE_BUFFER) {
                ata_dev_printk(dev, KERN_WARNING,
                               "_GTF unexpected object type 0x%x\n",
                               out_obj->type);
                rc = -EINVAL;
                goto out_free;
        }

        if (out_obj->buffer.length % REGS_PER_GTF) {
                ata_dev_printk(dev, KERN_WARNING,
                               "unexpected _GTF length (%d)\n",
                               out_obj->buffer.length);
                rc = -EINVAL;
                goto out_free;
        }

 done:
        rc = out_obj->buffer.length / REGS_PER_GTF;
        if (gtf) {
                *gtf = (void *)out_obj->buffer.pointer;
                if (ata_msg_probe(ap))
                        ata_dev_printk(dev, KERN_DEBUG,
                                       "%s: returning gtf=%p, gtf_count=%d\n",
                                       __FUNCTION__, *gtf, rc);
        }
        return rc;

 out_free:
        ata_acpi_clear_gtf(dev);
        return rc;
}

/**
 * ata_acpi_cbl_80wire          -       Check for 80 wire cable
 * @ap: Port to check
 *
 * Return 1 if the ACPI mode data for this port indicates the BIOS selected
 * an 80wire mode.
 */

int ata_acpi_cbl_80wire(struct ata_port *ap)
{
        const struct ata_acpi_gtm *gtm = ata_acpi_init_gtm(ap);
        int valid = 0;

        if (!gtm)
                return 0;

        /* Split timing, DMA enabled */
        if ((gtm->flags & 0x11) == 0x11 && gtm->drive[0].dma < 55)
                valid |= 1;
        if ((gtm->flags & 0x14) == 0x14 && gtm->drive[1].dma < 55)
                valid |= 2;
        /* Shared timing, DMA enabled */
        if ((gtm->flags & 0x11) == 0x01 && gtm->drive[0].dma < 55)
                valid |= 1;
        if ((gtm->flags & 0x14) == 0x04 && gtm->drive[0].dma < 55)
                valid |= 2;

        /* Drive check */
        if ((valid & 1) && ata_dev_enabled(&ap->link.device[0]))
                return 1;
        if ((valid & 2) && ata_dev_enabled(&ap->link.device[1]))
                return 1;
        return 0;
}

EXPORT_SYMBOL_GPL(ata_acpi_cbl_80wire);

static void ata_acpi_gtf_to_tf(struct ata_device *dev,
                               const struct ata_acpi_gtf *gtf,
                               struct ata_taskfile *tf)
{
        ata_tf_init(dev, tf);

        tf->flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        tf->protocol = ATA_PROT_NODATA;
        tf->feature = gtf->tf[0];       /* 0x1f1 */
        tf->nsect   = gtf->tf[1];       /* 0x1f2 */
        tf->lbal    = gtf->tf[2];       /* 0x1f3 */
        tf->lbam    = gtf->tf[3];       /* 0x1f4 */
        tf->lbah    = gtf->tf[4];       /* 0x1f5 */
        tf->device  = gtf->tf[5];       /* 0x1f6 */
        tf->command = gtf->tf[6];       /* 0x1f7 */
}

static int ata_acpi_filter_tf(const struct ata_taskfile *tf,
                              const struct ata_taskfile *ptf)
{
        if (ata_acpi_gtf_filter & ATA_ACPI_FILTER_SETXFER) {
                /* libata doesn't use ACPI to configure transfer mode.
                 * It will only confuse device configuration.  Skip.
                 */
                if (tf->command == ATA_CMD_SET_FEATURES &&
                    tf->feature == SETFEATURES_XFER)
                        return 1;
        }

        if (ata_acpi_gtf_filter & ATA_ACPI_FILTER_LOCK) {
                /* BIOS writers, sorry but we don't wanna lock
                 * features unless the user explicitly said so.
                 */

                /* DEVICE CONFIGURATION FREEZE LOCK */
                if (tf->command == ATA_CMD_CONF_OVERLAY &&
                    tf->feature == ATA_DCO_FREEZE_LOCK)
                        return 1;

                /* SECURITY FREEZE LOCK */
                if (tf->command == ATA_CMD_SEC_FREEZE_LOCK)
                        return 1;

                /* SET MAX LOCK and SET MAX FREEZE LOCK */
                if ((!ptf || ptf->command != ATA_CMD_READ_NATIVE_MAX) &&
                    tf->command == ATA_CMD_SET_MAX &&
                    (tf->feature == ATA_SET_MAX_LOCK ||
                     tf->feature == ATA_SET_MAX_FREEZE_LOCK))
                        return 1;
        }

        return 0;
}

/**
 * ata_acpi_run_tf - send taskfile registers to host controller
 * @dev: target ATA device
 * @gtf: raw ATA taskfile register set (0x1f1 - 0x1f7)
 *
 * Outputs ATA taskfile to standard ATA host controller using MMIO
 * or PIO as indicated by the ATA_FLAG_MMIO flag.
 * Writes the control, feature, nsect, lbal, lbam, and lbah registers.
 * Optionally (ATA_TFLAG_LBA48) writes hob_feature, hob_nsect,
 * hob_lbal, hob_lbam, and hob_lbah.
 *
 * This function waits for idle (!BUSY and !DRQ) after writing
 * registers.  If the control register has a new value, this
 * function also waits for idle after writing control and before
 * writing the remaining registers.
 *
 * LOCKING:
 * EH context.
 *
 * RETURNS:
 * 1 if command is executed successfully.  0 if ignored, rejected or
 * filtered out, -errno on other errors.
 */
static int ata_acpi_run_tf(struct ata_device *dev,
                           const struct ata_acpi_gtf *gtf,
                           const struct ata_acpi_gtf *prev_gtf)
{
        struct ata_taskfile *pptf = NULL;
        struct ata_taskfile tf, ptf, rtf;
        unsigned int err_mask;
        const char *level;
        char msg[60];
        int rc;

        if ((gtf->tf[0] == 0) && (gtf->tf[1] == 0) && (gtf->tf[2] == 0)
            && (gtf->tf[3] == 0) && (gtf->tf[4] == 0) && (gtf->tf[5] == 0)
            && (gtf->tf[6] == 0))
                return 0;

        ata_acpi_gtf_to_tf(dev, gtf, &tf);
        if (prev_gtf) {
                ata_acpi_gtf_to_tf(dev, prev_gtf, &ptf);
                pptf = &ptf;
        }

        if (!ata_acpi_filter_tf(&tf, pptf)) {
                rtf = tf;
                err_mask = ata_exec_internal(dev, &rtf, NULL,
                                             DMA_NONE, NULL, 0, 0);

                switch (err_mask) {
                case 0:
                        level = KERN_DEBUG;
                        snprintf(msg, sizeof(msg), "succeeded");
                        rc = 1;
                        break;

                case AC_ERR_DEV:
                        level = KERN_INFO;
                        snprintf(msg, sizeof(msg),
                                 "rejected by device (Stat=0x%02x Err=0x%02x)",
                                 rtf.command, rtf.feature);
                        rc = 0;
                        break;

                default:
                        level = KERN_ERR;
                        snprintf(msg, sizeof(msg),
                                 "failed (Emask=0x%x Stat=0x%02x Err=0x%02x)",
                                 err_mask, rtf.command, rtf.feature);
                        rc = -EIO;
                        break;
                }
        } else {
                level = KERN_INFO;
                snprintf(msg, sizeof(msg), "filtered out");
                rc = 0;
        }

        ata_dev_printk(dev, level,
                       "ACPI cmd %02x/%02x:%02x:%02x:%02x:%02x:%02x %s\n",
                       tf.command, tf.feature, tf.nsect, tf.lbal,
                       tf.lbam, tf.lbah, tf.device, msg);

        return rc;
}

/**
 * ata_acpi_exec_tfs - get then write drive taskfile settings
 * @dev: target ATA device
 * @nr_executed: out paramter for the number of executed commands
 *
 * Evaluate _GTF and excute returned taskfiles.
 *
 * LOCKING:
 * EH context.
 *
 * RETURNS:
 * Number of executed taskfiles on success, 0 if _GTF doesn't exist.
 * -errno on other errors.
 */
static int ata_acpi_exec_tfs(struct ata_device *dev, int *nr_executed)
{
        struct ata_acpi_gtf *gtf = NULL, *pgtf = NULL;
        int gtf_count, i, rc;

        /* get taskfiles */
        rc = ata_dev_get_GTF(dev, &gtf);
        if (rc < 0)
                return rc;
        gtf_count = rc;

        /* execute them */
        for (i = 0; i < gtf_count; i++, gtf++) {
                rc = ata_acpi_run_tf(dev, gtf, pgtf);
                if (rc < 0)
                        break;
                if (rc) {
                        (*nr_executed)++;
                        pgtf = gtf;
                }
        }

        ata_acpi_clear_gtf(dev);

        if (rc < 0)
                return rc;
        return 0;
}

/**
 * ata_acpi_push_id - send Identify data to drive
 * @dev: target ATA device
 *
 * _SDD ACPI object: for SATA mode only
 * Must be after Identify (Packet) Device -- uses its data
 * ATM this function never returns a failure.  It is an optional
 * method and if it fails for whatever reason, we should still
 * just keep going.
 *
 * LOCKING:
 * EH context.
 *
 * RETURNS:
 * 0 on success, -errno on failure.
 */
static int ata_acpi_push_id(struct ata_device *dev)
{
        struct ata_port *ap = dev->link->ap;
        int err;
        acpi_status status;
        struct acpi_object_list input;
        union acpi_object in_params[1];

        if (ata_msg_probe(ap))
                ata_dev_printk(dev, KERN_DEBUG, "%s: ix = %d, port#: %d\n",
                               __FUNCTION__, dev->devno, ap->port_no);

        /* Give the drive Identify data to the drive via the _SDD method */
        /* _SDD: set up input parameters */
        input.count = 1;
        input.pointer = in_params;
        in_params[0].type = ACPI_TYPE_BUFFER;
        in_params[0].buffer.length = sizeof(dev->id[0]) * ATA_ID_WORDS;
        in_params[0].buffer.pointer = (u8 *)dev->id;
        /* Output buffer: _SDD has no output */

        /* It's OK for _SDD to be missing too. */
        swap_buf_le16(dev->id, ATA_ID_WORDS);
        status = acpi_evaluate_object(dev->acpi_handle, "_SDD", &input, NULL);
        swap_buf_le16(dev->id, ATA_ID_WORDS);

        err = ACPI_FAILURE(status) ? -EIO : 0;
        if (err < 0)
                ata_dev_printk(dev, KERN_WARNING,
                               "ACPI _SDD failed (AE 0x%x)\n", status);

        return err;
}

/**
 * ata_acpi_on_suspend - ATA ACPI hook called on suspend
 * @ap: target ATA port
 *
 * This function is called when @ap is about to be suspended.  All
 * devices are already put to sleep but the port_suspend() callback
 * hasn't been executed yet.  Error return from this function aborts
 * suspend.
 *
 * LOCKING:
 * EH context.
 *
 * RETURNS:
 * 0 on success, -errno on failure.
 */
int ata_acpi_on_suspend(struct ata_port *ap)
{
        /* nada */
        return 0;
}

/**
 * ata_acpi_on_resume - ATA ACPI hook called on resume
 * @ap: target ATA port
 *
 * This function is called when @ap is resumed - right after port
 * itself is resumed but before any EH action is taken.
 *
 * LOCKING:
 * EH context.
 */
void ata_acpi_on_resume(struct ata_port *ap)
{
        const struct ata_acpi_gtm *gtm = ata_acpi_init_gtm(ap);
        struct ata_device *dev;

        if (ap->acpi_handle && gtm) {
                /* _GTM valid */

                /* restore timing parameters */
                ata_acpi_stm(ap, gtm);

                /* _GTF should immediately follow _STM so that it can
                 * use values set by _STM.  Cache _GTF result and
                 * schedule _GTF.
                 */
                ata_link_for_each_dev(dev, &ap->link) {
                        ata_acpi_clear_gtf(dev);
                        if (ata_dev_get_GTF(dev, NULL) >= 0)
                                dev->flags |= ATA_DFLAG_ACPI_PENDING;
                }
        } else {
                /* SATA _GTF needs to be evaulated after _SDD and
                 * there's no reason to evaluate IDE _GTF early
                 * without _STM.  Clear cache and schedule _GTF.
                 */
                ata_link_for_each_dev(dev, &ap->link) {
                        ata_acpi_clear_gtf(dev);
                        dev->flags |= ATA_DFLAG_ACPI_PENDING;
                }
        }
}

/**
 * ata_acpi_on_devcfg - ATA ACPI hook called on device donfiguration
 * @dev: target ATA device
 *
 * This function is called when @dev is about to be configured.
 * IDENTIFY data might have been modified after this hook is run.
 *
 * LOCKING:
 * EH context.
 *
 * RETURNS:
 * Positive number if IDENTIFY data needs to be refreshed, 0 if not,
 * -errno on failure.
 */
int ata_acpi_on_devcfg(struct ata_device *dev)
{
        struct ata_port *ap = dev->link->ap;
        struct ata_eh_context *ehc = &ap->link.eh_context;
        int acpi_sata = ap->flags & ATA_FLAG_ACPI_SATA;
        int nr_executed = 0;
        int rc;

        if (!dev->acpi_handle)
                return 0;

        /* do we need to do _GTF? */
        if (!(dev->flags & ATA_DFLAG_ACPI_PENDING) &&
            !(acpi_sata && (ehc->i.flags & ATA_EHI_DID_HARDRESET)))
                return 0;

        /* do _SDD if SATA */
        if (acpi_sata) {
                rc = ata_acpi_push_id(dev);
                if (rc)
                        goto acpi_err;
        }

        /* do _GTF */
        rc = ata_acpi_exec_tfs(dev, &nr_executed);
        if (rc)
                goto acpi_err;

        dev->flags &= ~ATA_DFLAG_ACPI_PENDING;

        /* refresh IDENTIFY page if any _GTF command has been executed */
        if (nr_executed) {
                rc = ata_dev_reread_id(dev, 0);
                if (rc < 0) {
                        ata_dev_printk(dev, KERN_ERR, "failed to IDENTIFY "
                                       "after ACPI commands\n");
                        return rc;
                }
        }

        return 0;

 acpi_err:
        /* ignore evaluation failure if we can continue safely */
        if (rc == -EINVAL && !nr_executed && !(ap->pflags & ATA_PFLAG_FROZEN))
                return 0;

        /* fail and let EH retry once more for unknown IO errors */
        if (!(dev->flags & ATA_DFLAG_ACPI_FAILED)) {
                dev->flags |= ATA_DFLAG_ACPI_FAILED;
                return rc;
        }

        ata_dev_printk(dev, KERN_WARNING,
                       "ACPI: failed the second time, disabled\n");
        dev->acpi_handle = NULL;

        /* We can safely continue if no _GTF command has been executed
         * and port is not frozen.
         */
        if (!nr_executed && !(ap->pflags & ATA_PFLAG_FROZEN))
                return 0;

        return rc;
}

/**
 * ata_acpi_on_disable - ATA ACPI hook called when a device is disabled
 * @dev: target ATA device
 *
 * This function is called when @dev is about to be disabled.
 *
 * LOCKING:
 * EH context.
 */
void ata_acpi_on_disable(struct ata_device *dev)
{
        ata_acpi_clear_gtf(dev);
}