ACPI support for IDE devices

This patch implements ACPI integration for generic IDE devices.
The ACPI spec mandates that some methods are called during suspend and
resume. And consequently there most modern Laptops cannot resume
properly without it.

According to the spec, we should call '_GTM' (Get Timing) upon suspend
to store the current IDE adapter settings.
Upon resume we should call '_STM' (Set Timing) to initialize the
adapter with the stored settings; afterwards '_GTF' (Get Taskfile)
should be called which returns a buffer with some IDE initialisation
commands. Those commands should be passed to the drive.

There are two module params which control the behaviour of this patch:

'ide=noacpi'
	Do not call any ACPI methods (Disables any ACPI method calls)
'ide=acpigtf'
	Enable execution of _GTF methods upon resume.
	Has no effect if 'ide=noacpi' is set.
'ide=acpionboot'
	Enable execution of ACPI methods during boot.
	This might be required on some machines if 'ide=acpigtf' is
	selected as some machines modify the _GTF information
	depending on the drive identification passed down with _STM.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 696 insertions, 0 deletions

diff --git a/drivers/ide/ide-acpi.c b/drivers/ide/ide-acpi.c
new file mode 100644
index 000000000000..1eb734951dc9
--- /dev/null
+++ b/drivers/ide/ide-acpi.c
@@ -0,0 +1,696 @@
+/*
+ * ide-acpi.c
+ * Provides ACPI support for IDE drives.
+ *
+ * Copyright (C) 2005 Intel Corp.
+ * Copyright (C) 2005 Randy Dunlap
+ * Copyright (C) 2006 SUSE Linux Products GmbH
+ * Copyright (C) 2006 Hannes Reinecke
+ */
+
+#include <linux/ata.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <acpi/acpi.h>
+#include <linux/ide.h>
+#include <linux/pci.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>
+
+#define REGS_PER_GTF		7
+struct taskfile_array {
+	u8	tfa[REGS_PER_GTF];	/* regs. 0x1f1 - 0x1f7 */
+};
+
+struct GTM_buffer {
+	u32	PIO_speed0;
+	u32	DMA_speed0;
+	u32	PIO_speed1;
+	u32	DMA_speed1;
+	u32	GTM_flags;
+};
+
+struct ide_acpi_drive_link {
+	ide_drive_t	*drive;
+	acpi_handle	 obj_handle;
+	u8		 idbuff[512];
+};
+
+struct ide_acpi_hwif_link {
+	ide_hwif_t			*hwif;
+	acpi_handle			 obj_handle;
+	struct GTM_buffer		 gtm;
+	struct ide_acpi_drive_link	 master;
+	struct ide_acpi_drive_link	 slave;
+};
+
+#undef DEBUGGING
+/* note: adds function name and KERN_DEBUG */
+#ifdef DEBUGGING
+#define DEBPRINT(fmt, args...)	\
+		printk(KERN_DEBUG "%s: " fmt, __FUNCTION__, ## args)
+#else
+#define DEBPRINT(fmt, args...)	do {} while (0)
+#endif	/* DEBUGGING */
+
+extern int ide_noacpi;
+extern int ide_noacpitfs;
+extern int ide_noacpionboot;
+
+/**
+ * ide_get_dev_handle - finds acpi_handle and PCI device.function
+ * @dev: device to locate
+ * @handle: returned acpi_handle for @dev
+ * @pcidevfn: return PCI device.func for @dev
+ *
+ * Returns the ACPI object handle to the corresponding PCI device.
+ *
+ * Returns 0 on success, <0 on error.
+ */
+static int ide_get_dev_handle(struct device *dev, acpi_handle *handle,
+			       acpi_integer *pcidevfn)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	unsigned int bus, devnum, func;
+	acpi_integer addr;
+	acpi_handle dev_handle;
+	struct acpi_buffer buffer = {.length = ACPI_ALLOCATE_BUFFER,
+					.pointer = NULL};
+	acpi_status status;
+	struct acpi_device_info	*dinfo = NULL;
+	int ret = -ENODEV;
+
+	bus = pdev->bus->number;
+	devnum = PCI_SLOT(pdev->devfn);
+	func = PCI_FUNC(pdev->devfn);
+	/* ACPI _ADR encoding for PCI bus: */
+	addr = (acpi_integer)(devnum << 16 | func);
+
+	DEBPRINT("ENTER: pci %02x:%02x.%01x\n", bus, devnum, func);
+
+	dev_handle = DEVICE_ACPI_HANDLE(dev);
+	if (!dev_handle) {
+		DEBPRINT("no acpi handle for device\n");
+		goto err;
+	}
+
+	status = acpi_get_object_info(dev_handle, &buffer);
+	if (ACPI_FAILURE(status)) {
+		DEBPRINT("get_object_info for device failed\n");
+		goto err;
+	}
+	dinfo = buffer.pointer;
+	if (dinfo && (dinfo->valid & ACPI_VALID_ADR) &&
+	    dinfo->address == addr) {
+		*pcidevfn = addr;
+		*handle = dev_handle;
+	} else {
+		DEBPRINT("get_object_info for device has wrong "
+			" address: %llu, should be %u\n",
+			dinfo ? (unsigned long long)dinfo->address : -1ULL,
+			(unsigned int)addr);
+		goto err;
+	}
+
+	DEBPRINT("for dev=0x%x.%x, addr=0x%llx, *handle=0x%p\n",
+		 devnum, func, (unsigned long long)addr, *handle);
+	ret = 0;
+err:
+	kfree(dinfo);
+	return ret;
+}
+
+/**
+ * ide_acpi_hwif_get_handle - Get ACPI object handle for a given hwif
+ * @hwif: device to locate
+ *
+ * Retrieves the object handle for a given hwif.
+ *
+ * Returns handle on success, 0 on error.
+ */
+static acpi_handle ide_acpi_hwif_get_handle(ide_hwif_t *hwif)
+{
+	struct device		*dev = hwif->gendev.parent;
+	acpi_handle		dev_handle;
+	acpi_integer		pcidevfn;
+	acpi_handle		chan_handle;
+	int			err;
+
+	DEBPRINT("ENTER: device %s\n", hwif->name);
+
+	if (!dev) {
+		DEBPRINT("no PCI device for %s\n", hwif->name);
+		return NULL;
+	}
+
+	err = ide_get_dev_handle(dev, &dev_handle, &pcidevfn);
+	if (err < 0) {
+		DEBPRINT("ide_get_dev_handle failed (%d)\n", err);
+		return NULL;
+	}
+
+	/* get child objects of dev_handle == channel objects,
+	 * + _their_ children == drive objects */
+	/* channel is hwif->channel */
+	chan_handle = acpi_get_child(dev_handle, hwif->channel);
+	DEBPRINT("chan adr=%d: handle=0x%p\n",
+		 hwif->channel, chan_handle);
+
+	return chan_handle;
+}
+
+/**
+ * ide_acpi_drive_get_handle - Get ACPI object handle for a given drive
+ * @drive: device to locate
+ *
+ * Retrieves the object handle of a given drive. According to the ACPI
+ * spec the drive is a child of the hwif.
+ *
+ * Returns handle on success, 0 on error.
+ */
+static acpi_handle ide_acpi_drive_get_handle(ide_drive_t *drive)
+{
+	ide_hwif_t	*hwif = HWIF(drive);
+	int		 port;
+	acpi_handle	 drive_handle;
+
+	if (!hwif->acpidata)
+		return NULL;
+
+	if (!hwif->acpidata->obj_handle)
+		return NULL;
+
+	port = hwif->channel ? drive->dn - 2: drive->dn;
+
+	DEBPRINT("ENTER: %s at channel#: %d port#: %d\n",
+		 drive->name, hwif->channel, port);
+
+
+	/* TBD: could also check ACPI object VALID bits */
+	drive_handle = acpi_get_child(hwif->acpidata->obj_handle, port);
+	DEBPRINT("drive %s handle 0x%p\n", drive->name, drive_handle);
+
+	return drive_handle;
+}
+
+/**
+ * do_drive_get_GTF - get the drive bootup default taskfile settings
+ * @drive: the drive for which the taskfile settings should be retrieved
+ * @gtf_length: number of bytes of _GTF data returned at @gtf_address
+ * @gtf_address: buffer containing _GTF taskfile arrays
+ *
+ * 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.
+ *
+ * The returned @gtf_length and @gtf_address are only valid if the
+ * function return value is 0.
+ */
+static int do_drive_get_GTF(ide_drive_t *drive,
+		     unsigned int *gtf_length, unsigned long *gtf_address,
+		     unsigned long *obj_loc)
+{
+	acpi_status			status;
+	struct acpi_buffer		output;
+	union acpi_object 		*out_obj;
+	ide_hwif_t			*hwif = HWIF(drive);
+	struct device			*dev = hwif->gendev.parent;
+	int				err = -ENODEV;
+	int				port;
+
+	*gtf_length = 0;
+	*gtf_address = 0UL;
+	*obj_loc = 0UL;
+
+	if (ide_noacpi)
+		return 0;
+
+	if (!dev) {
+		DEBPRINT("no PCI device for %s\n", hwif->name);
+		goto out;
+	}
+
+	if (!hwif->acpidata) {
+		DEBPRINT("no ACPI data for %s\n", hwif->name);
+		goto out;
+	}
+
+	port = hwif->channel ? drive->dn - 2: drive->dn;
+
+	if (!drive->acpidata) {
+		if (port == 0) {
+			drive->acpidata = &hwif->acpidata->master;
+			hwif->acpidata->master.drive = drive;
+		} else {
+			drive->acpidata = &hwif->acpidata->slave;
+			hwif->acpidata->slave.drive = drive;
+		}
+	}
+
+	DEBPRINT("ENTER: %s at %s, port#: %d, hard_port#: %d\n",
+		 hwif->name, dev->bus_id, port, hwif->channel);
+
+	if (!drive->present) {
+		DEBPRINT("%s drive %d:%d not present\n",
+			 hwif->name, hwif->channel, port);
+		goto out;
+	}
+
+	/* Get this drive's _ADR info. if not already known. */
+	if (!drive->acpidata->obj_handle) {
+		drive->acpidata->obj_handle = ide_acpi_drive_get_handle(drive);
+		if (!drive->acpidata->obj_handle) {
+			DEBPRINT("No ACPI object found for %s\n",
+				 drive->name);
+			goto out;
+		}
+	}
+
+	/* Setting up output buffer */
+	output.length = ACPI_ALLOCATE_BUFFER;
+	output.pointer = NULL;	/* ACPI-CA sets this; save/free it later */
+
+	/* _GTF has no input parameters */
+	err = -EIO;
+	status = acpi_evaluate_object(drive->acpidata->obj_handle, "_GTF",
+				      NULL, &output);
+	if (ACPI_FAILURE(status)) {
+		printk(KERN_DEBUG
+		       "%s: Run _GTF error: status = 0x%x\n",
+		       __FUNCTION__, status);
+		goto out;
+	}
+
+	if (!output.length || !output.pointer) {
+		DEBPRINT("Run _GTF: "
+		       "length or ptr is NULL (0x%llx, 0x%p)\n",
+		       (unsigned long long)output.length,
+		       output.pointer);
+		goto out;
+	}
+
+	out_obj = output.pointer;
+	if (out_obj->type != ACPI_TYPE_BUFFER) {
+		DEBPRINT("Run _GTF: error: "
+		       "expected object type of ACPI_TYPE_BUFFER, "
+		       "got 0x%x\n", out_obj->type);
+		err = -ENOENT;
+		kfree(output.pointer);
+		goto out;
+	}
+
+	if (!out_obj->buffer.length || !out_obj->buffer.pointer ||
+	    out_obj->buffer.length % REGS_PER_GTF) {
+		printk(KERN_ERR
+		       "%s: unexpected GTF length (%d) or addr (0x%p)\n",
+		       __FUNCTION__, out_obj->buffer.length,
+		       out_obj->buffer.pointer);
+		err = -ENOENT;
+		kfree(output.pointer);
+		goto out;
+	}
+
+	*gtf_length = out_obj->buffer.length;
+	*gtf_address = (unsigned long)out_obj->buffer.pointer;
+	*obj_loc = (unsigned long)out_obj;
+	DEBPRINT("returning gtf_length=%d, gtf_address=0x%lx, obj_loc=0x%lx\n",
+		 *gtf_length, *gtf_address, *obj_loc);
+	err = 0;
+out:
+	return err;
+}
+
+/**
+ * taskfile_load_raw - send taskfile registers to drive
+ * @drive: drive to which output is sent
+ * @gtf: raw ATA taskfile register set (0x1f1 - 0x1f7)
+ *
+ * Outputs IDE taskfile to the drive.
+ */
+static int taskfile_load_raw(ide_drive_t *drive,
+			      const struct taskfile_array *gtf)
+{
+	ide_task_t args;
+	int err = 0;
+
+	DEBPRINT("(0x1f1-1f7): hex: "
+	       "%02x %02x %02x %02x %02x %02x %02x\n",
+	       gtf->tfa[0], gtf->tfa[1], gtf->tfa[2],
+	       gtf->tfa[3], gtf->tfa[4], gtf->tfa[5], gtf->tfa[6]);
+
+	memset(&args, 0, sizeof(ide_task_t));
+	args.command_type = IDE_DRIVE_TASK_NO_DATA;
+	args.data_phase   = TASKFILE_IN;
+	args.handler      = &task_no_data_intr;
+
+	/* convert gtf to IDE Taskfile */
+	args.tfRegister[1] = gtf->tfa[0];	/* 0x1f1 */
+	args.tfRegister[2] = gtf->tfa[1];	/* 0x1f2 */
+	args.tfRegister[3] = gtf->tfa[2];	/* 0x1f3 */
+	args.tfRegister[4] = gtf->tfa[3];	/* 0x1f4 */
+	args.tfRegister[5] = gtf->tfa[4];	/* 0x1f5 */
+	args.tfRegister[6] = gtf->tfa[5];	/* 0x1f6 */
+	args.tfRegister[7] = gtf->tfa[6];	/* 0x1f7 */
+
+	if (ide_noacpitfs) {
+		DEBPRINT("_GTF execution disabled\n");
+		return err;
+	}
+
+	err = ide_raw_taskfile(drive, &args, NULL);
+	if (err)
+		printk(KERN_ERR "%s: ide_raw_taskfile failed: %u\n",
+		       __FUNCTION__, err);
+
+	return err;
+}
+
+/**
+ * do_drive_set_taskfiles - write the drive taskfile settings from _GTF
+ * @drive: the drive to which the taskfile command should be sent
+ * @gtf_length: total number of bytes of _GTF taskfiles
+ * @gtf_address: location of _GTF taskfile arrays
+ *
+ * Write {gtf_address, length gtf_length} in groups of
+ * REGS_PER_GTF bytes.
+ */
+static int do_drive_set_taskfiles(ide_drive_t *drive,
+				  unsigned int gtf_length,
+				  unsigned long gtf_address)
+{
+	int			rc = -ENODEV, err;
+	int			gtf_count = gtf_length / REGS_PER_GTF;
+	int			ix;
+	struct taskfile_array	*gtf;
+
+	if (ide_noacpi)
+		return 0;
+
+	DEBPRINT("ENTER: %s, hard_port#: %d\n", drive->name, drive->dn);
+
+	if (!drive->present)
+		goto out;
+	if (!gtf_count)		/* shouldn't be here */
+		goto out;
+
+	DEBPRINT("total GTF bytes=%u (0x%x), gtf_count=%d, addr=0x%lx\n",
+		 gtf_length, gtf_length, gtf_count, gtf_address);
+
+	if (gtf_length % REGS_PER_GTF) {
+		printk(KERN_ERR "%s: unexpected GTF length (%d)\n",
+		       __FUNCTION__, gtf_length);
+		goto out;
+	}
+
+	rc = 0;
+	for (ix = 0; ix < gtf_count; ix++) {
+		gtf = (struct taskfile_array *)
+			(gtf_address + ix * REGS_PER_GTF);
+
+		/* send all TaskFile registers (0x1f1-0x1f7) *in*that*order* */
+		err = taskfile_load_raw(drive, gtf);
+		if (err)
+			rc = err;
+	}
+
+out:
+	return rc;
+}
+
+/**
+ * ide_acpi_exec_tfs - get then write drive taskfile settings
+ * @drive: the drive for which the taskfile settings should be
+ *         written.
+ *
+ * According to the ACPI spec this should be called after _STM
+ * has been evaluated for the interface. Some ACPI vendors interpret
+ * that as a hard requirement and modify the taskfile according
+ * to the Identify Drive information passed down with _STM.
+ * So one should really make sure to call this only after _STM has
+ * been executed.
+ */
+int ide_acpi_exec_tfs(ide_drive_t *drive)
+{
+	int		ret;
+	unsigned int	gtf_length;
+	unsigned long	gtf_address;
+	unsigned long	obj_loc;
+
+	if (ide_noacpi)
+		return 0;
+
+	DEBPRINT("call get_GTF, drive=%s port=%d\n", drive->name, drive->dn);
+
+	ret = do_drive_get_GTF(drive, &gtf_length, &gtf_address, &obj_loc);
+	if (ret < 0) {
+		DEBPRINT("get_GTF error (%d)\n", ret);
+		return ret;
+	}
+
+	DEBPRINT("call set_taskfiles, drive=%s\n", drive->name);
+
+	ret = do_drive_set_taskfiles(drive, gtf_length, gtf_address);
+	kfree((void *)obj_loc);
+	if (ret < 0) {
+		DEBPRINT("set_taskfiles error (%d)\n", ret);
+	}
+
+	DEBPRINT("ret=%d\n", ret);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(ide_acpi_exec_tfs);
+
+/**
+ * ide_acpi_get_timing - get the channel (controller) timings
+ * @hwif: target IDE interface (channel)
+ *
+ * This function executes the _GTM ACPI method for the target channel.
+ *
+ */
+void ide_acpi_get_timing(ide_hwif_t *hwif)
+{
+	acpi_status		status;
+	struct acpi_buffer	output;
+	union acpi_object 	*out_obj;
+
+	if (ide_noacpi)
+		return;
+
+	DEBPRINT("ENTER:\n");
+
+	if (!hwif->acpidata) {
+		DEBPRINT("no ACPI data for %s\n", hwif->name);
+		return;
+	}
+
+	/* Setting up output buffer for _GTM */
+	output.length = ACPI_ALLOCATE_BUFFER;
+	output.pointer = NULL;	/* ACPI-CA sets this; save/free it later */
+
+	/* _GTM has no input parameters */
+	status = acpi_evaluate_object(hwif->acpidata->obj_handle, "_GTM",
+				      NULL, &output);
+
+	DEBPRINT("_GTM status: %d, outptr: 0x%p, outlen: 0x%llx\n",
+		 status, output.pointer,
+		 (unsigned long long)output.length);
+
+	if (ACPI_FAILURE(status)) {
+		DEBPRINT("Run _GTM error: status = 0x%x\n", status);
+		return;
+	}
+
+	if (!output.length || !output.pointer) {
+		DEBPRINT("Run _GTM: length or ptr is NULL (0x%llx, 0x%p)\n",
+		       (unsigned long long)output.length,
+		       output.pointer);
+		kfree(output.pointer);
+		return;
+	}
+
+	out_obj = output.pointer;
+	if (out_obj->type != ACPI_TYPE_BUFFER) {
+		kfree(output.pointer);
+		DEBPRINT("Run _GTM: error: "
+		       "expected object type of ACPI_TYPE_BUFFER, "
+		       "got 0x%x\n", out_obj->type);
+		return;
+	}
+
+	if (!out_obj->buffer.length || !out_obj->buffer.pointer ||
+	    out_obj->buffer.length != sizeof(struct GTM_buffer)) {
+		kfree(output.pointer);
+		printk(KERN_ERR
+		       "%s: unexpected _GTM length (0x%x)[should be 0x%x] or addr (0x%p)\n",
+		       __FUNCTION__, out_obj->buffer.length,
+		       sizeof(struct GTM_buffer), out_obj->buffer.pointer);
+		return;
+	}
+
+	memcpy(&hwif->acpidata->gtm, out_obj->buffer.pointer,
+	       sizeof(struct GTM_buffer));
+
+	DEBPRINT("_GTM info: ptr: 0x%p, len: 0x%x, exp.len: 0x%Zx\n",
+		 out_obj->buffer.pointer, out_obj->buffer.length,
+		 sizeof(struct GTM_buffer));
+
+	DEBPRINT("_GTM fields: 0x%x, 0x%x, 0x%x, 0x%x, 0x%x\n",
+		 hwif->acpidata->gtm.PIO_speed0,
+		 hwif->acpidata->gtm.DMA_speed0,
+		 hwif->acpidata->gtm.PIO_speed1,
+		 hwif->acpidata->gtm.DMA_speed1,
+		 hwif->acpidata->gtm.GTM_flags);
+
+	kfree(output.pointer);
+}
+EXPORT_SYMBOL_GPL(ide_acpi_get_timing);
+
+/**
+ * ide_acpi_push_timing - set the channel (controller) timings
+ * @hwif: target IDE interface (channel)
+ *
+ * This function executes the _STM ACPI method for the target channel.
+ *
+ * _STM requires Identify Drive data, which has to passed as an argument.
+ * Unfortunately hd_driveid is a mangled version which we can't readily
+ * use; hence we'll get the information afresh.
+ */
+void ide_acpi_push_timing(ide_hwif_t *hwif)
+{
+	acpi_status		status;
+	struct acpi_object_list	input;
+	union acpi_object 	in_params[3];
+	struct ide_acpi_drive_link	*master = &hwif->acpidata->master;
+	struct ide_acpi_drive_link	*slave = &hwif->acpidata->slave;
+
+	if (ide_noacpi)
+		return;
+
+	DEBPRINT("ENTER:\n");
+
+	if (!hwif->acpidata) {
+		DEBPRINT("no ACPI data for %s\n", hwif->name);
+		return;
+	}
+
+	/* Give the GTM buffer + drive Identify data to the channel via the
+	 * _STM method: */
+	/* setup input parameters buffer for _STM */
+	input.count = 3;
+	input.pointer = in_params;
+	in_params[0].type = ACPI_TYPE_BUFFER;
+	in_params[0].buffer.length = sizeof(struct GTM_buffer);
+	in_params[0].buffer.pointer = (u8 *)&hwif->acpidata->gtm;
+	in_params[1].type = ACPI_TYPE_BUFFER;
+	in_params[1].buffer.length = sizeof(struct hd_driveid);
+	in_params[1].buffer.pointer = (u8 *)&master->idbuff;
+	in_params[2].type = ACPI_TYPE_BUFFER;
+	in_params[2].buffer.length = sizeof(struct hd_driveid);
+	in_params[2].buffer.pointer = (u8 *)&slave->idbuff;
+	/* Output buffer: _STM has no output */
+
+	status = acpi_evaluate_object(hwif->acpidata->obj_handle, "_STM",
+				      &input, NULL);
+
+	if (ACPI_FAILURE(status)) {
+		DEBPRINT("Run _STM error: status = 0x%x\n", status);
+	}
+	DEBPRINT("_STM status: %d\n", status);
+}
+EXPORT_SYMBOL_GPL(ide_acpi_push_timing);
+
+/**
+ * ide_acpi_init - initialize the ACPI link for an IDE interface
+ * @hwif: target IDE interface (channel)
+ *
+ * The ACPI spec is not quite clear when the drive identify buffer
+ * should be obtained. Calling IDENTIFY DEVICE during shutdown
+ * is not the best of ideas as the drive might already being put to
+ * sleep. And obviously we can't call it during resume.
+ * So we get the information during startup; but this means that
+ * any changes during run-time will be lost after resume.
+ */
+void ide_acpi_init(ide_hwif_t *hwif)
+{
+	int unit;
+	int			err;
+	struct ide_acpi_drive_link	*master;
+	struct ide_acpi_drive_link	*slave;
+
+	hwif->acpidata = kzalloc(sizeof(struct ide_acpi_hwif_link), GFP_KERNEL);
+	if (!hwif->acpidata)
+		return;
+
+	hwif->acpidata->obj_handle = ide_acpi_hwif_get_handle(hwif);
+	if (!hwif->acpidata->obj_handle) {
+		DEBPRINT("no ACPI object for %s found\n", hwif->name);
+		kfree(hwif->acpidata);
+		hwif->acpidata = NULL;
+		return;
+	}
+
+	/*
+	 * The ACPI spec mandates that we send information
+	 * for both drives, regardless whether they are connected
+	 * or not.
+	 */
+	hwif->acpidata->master.drive = &hwif->drives[0];
+	hwif->drives[0].acpidata = &hwif->acpidata->master;
+	master = &hwif->acpidata->master;
+
+	hwif->acpidata->slave.drive = &hwif->drives[1];
+	hwif->drives[1].acpidata = &hwif->acpidata->slave;
+	slave = &hwif->acpidata->slave;
+
+
+	/*
+	 * Send IDENTIFY for each drive
+	 */
+	if (master->drive->present) {
+		err = taskfile_lib_get_identify(master->drive, master->idbuff);
+		if (err) {
+			DEBPRINT("identify device %s failed (%d)\n",
+				 master->drive->name, err);
+		}
+	}
+
+	if (slave->drive->present) {
+		err = taskfile_lib_get_identify(slave->drive, slave->idbuff);
+		if (err) {
+			DEBPRINT("identify device %s failed (%d)\n",
+				 slave->drive->name, err);
+		}
+	}
+
+	if (ide_noacpionboot) {
+		DEBPRINT("ACPI methods disabled on boot\n");
+		return;
+	}
+
+	/*
+	 * ACPI requires us to call _STM on startup
+	 */
+	ide_acpi_get_timing(hwif);
+	ide_acpi_push_timing(hwif);
+
+	for (unit = 0; unit < MAX_DRIVES; ++unit) {
+		ide_drive_t *drive = &hwif->drives[unit];
+
+		if (drive->present) {
+			/* Execute ACPI startup code */
+			ide_acpi_exec_tfs(drive);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(ide_acpi_init);