ahci: mcp89: enter AHCI mode under Apple BIOS emulation

Apple's BIOS emulation forcibly disables MCP89 AHCI, eg. on Macbook7,1.
We can re-enable it, replacing the previous workaround of using
ata_generic.

tj: whitespace adjustments, dropped inline from is_mcp89_apple()

Signed-off-by: James Laird <[e-mail]>
Signed-off-by: Tejun Heo <[e-mail]>

drivers/ata/ahci.c

···
 static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent);
 static int ahci_vt8251_hardreset(struct ata_link *link, unsigned int *class,
 				 unsigned long deadline);
+static void ahci_mcp89_apple_enable(struct pci_dev *pdev);
+static bool is_mcp89_apple(struct pci_dev *pdev);
 static int ahci_p5wdh_hardreset(struct ata_link *link, unsigned int *class,
 				unsigned long deadline);
 #ifdef CONFIG_PM
···
 	if (rc)
 		return rc;
 
+	/* Apple BIOS helpfully mangles the registers on resume */
+	if (is_mcp89_apple(pdev))
+		ahci_mcp89_apple_enable(pdev);
+
 	if (pdev->dev.power.power_state.event == PM_EVENT_SUSPEND) {
 		rc = ahci_pci_reset_controller(host);
 		if (rc)
···
 		ap->ops = &ahci_p5wdh_ops;
 		ap->link.flags |= ATA_LFLAG_NO_SRST | ATA_LFLAG_ASSUME_ATA;
 	}
+}
+
+/*
+ * Macbook7,1 firmware forcibly disables MCP89 AHCI and changes PCI ID when
+ * booting in BIOS compatibility mode.  We restore the registers but not ID.
+ */
+static void ahci_mcp89_apple_enable(struct pci_dev *pdev)
+{
+	u32 val;
+
+	printk(KERN_INFO "ahci: enabling MCP89 AHCI mode\n");
+
+	pci_read_config_dword(pdev, 0xf8, &val);
+	val |= 1 << 0x1b;
+	/* the following changes the device ID, but appears not to affect function */
+	/* val = (val & ~0xf0000000) | 0x80000000; */
+	pci_write_config_dword(pdev, 0xf8, val);
+
+	pci_read_config_dword(pdev, 0x54c, &val);
+	val |= 1 << 0xc;
+	pci_write_config_dword(pdev, 0x54c, val);
+
+	pci_read_config_dword(pdev, 0x4a4, &val);
+	val &= 0xff;
+	val |= 0x01060100;
+	pci_write_config_dword(pdev, 0x4a4, val);
+
+	pci_read_config_dword(pdev, 0x54c, &val);
+	val &= ~(1 << 0xc);
+	pci_write_config_dword(pdev, 0x54c, val);
+
+	pci_read_config_dword(pdev, 0xf8, &val);
+	val &= ~(1 << 0x1b);
+	pci_write_config_dword(pdev, 0xf8, val);
+}
+
+static bool is_mcp89_apple(struct pci_dev *pdev)
+{
+	return pdev->vendor == PCI_VENDOR_ID_NVIDIA &&
+		pdev->device == PCI_DEVICE_ID_NVIDIA_NFORCE_MCP89_SATA &&
+		pdev->subsystem_vendor == PCI_VENDOR_ID_APPLE &&
+		pdev->subsystem_device == 0xcb89;
 }
 
 /* only some SB600 ahci controllers can do 64bit DMA */
···
 	if (pdev->vendor == PCI_VENDOR_ID_MARVELL && !marvell_enable)
 		return -ENODEV;
 
-	/*
-	 * For some reason, MCP89 on MacBook 7,1 doesn't work with
-	 * ahci, use ata_generic instead.
-	 */
-	if (pdev->vendor == PCI_VENDOR_ID_NVIDIA &&
-	    pdev->device == PCI_DEVICE_ID_NVIDIA_NFORCE_MCP89_SATA &&
-	    pdev->subsystem_vendor == PCI_VENDOR_ID_APPLE &&
-	    pdev->subsystem_device == 0xcb89)
-		return -ENODEV;
+	/* Apple BIOS on MCP89 prevents us using AHCI */
+	if (is_mcp89_apple(pdev))
+		ahci_mcp89_apple_enable(pdev);
 
 	/* Promise's PDC42819 is a SAS/SATA controller that has an AHCI mode.
 	 * At the moment, we can only use the AHCI mode. Let the users know

drivers/ata/ata_generic.c

···
 	{ PCI_DEVICE(PCI_VENDOR_ID_OPTI,   PCI_DEVICE_ID_OPTI_82C558), },
 	{ PCI_DEVICE(PCI_VENDOR_ID_CENATEK,PCI_DEVICE_ID_CENATEK_IDE),
 	  .driver_data = ATA_GEN_FORCE_DMA },
-	/*
-	 * For some reason, MCP89 on MacBook 7,1 doesn't work with
-	 * ahci, use ata_generic instead.
-	 */
-	{ PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_NFORCE_MCP89_SATA,
-	  PCI_VENDOR_ID_APPLE, 0xcb89,
-	  .driver_data = ATA_GEN_FORCE_DMA },
 #if !defined(CONFIG_PATA_TOSHIBA) && !defined(CONFIG_PATA_TOSHIBA_MODULE)
 	{ PCI_DEVICE(PCI_VENDOR_ID_TOSHIBA,PCI_DEVICE_ID_TOSHIBA_PICCOLO_1), },
 	{ PCI_DEVICE(PCI_VENDOR_ID_TOSHIBA,PCI_DEVICE_ID_TOSHIBA_PICCOLO_2),  },