drm/i915: add plumbing for SWSCI

SWSCI is a driver to bios call interface.

This checks for SWSCI availability and bios requested callbacks, and
filters out any calls that shouldn't happen. This way the callers don't
need to do the checks all over the place.

v2: silence some checkpatch nagging

v3: set PCI_SWSCI bit 0 to trigger interrupt (Mengdong Lin)

v4: remove an extra #define (Jesse)

v5: spec says s/w is responsible for clearing PCI_SWSCI bit 0 too

v6: per Paulo's review and more:
 - fix sub-function mask
 - add exit parameter
 - add define for set panel details call
 - return more errors from swsci
 - clean up the supported/requested callbacks bit masks mess
 - use DSLP for timeout
 - fix build for CONFIG_ACPI=n

v7: tiny adjustment of requested vs. supported SBCB callbacks handling (Paulo)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -225,6 +225,8 @@ struct intel_opregion {
 	struct opregion_header __iomem *header;
 	struct opregion_acpi __iomem *acpi;
 	struct opregion_swsci __iomem *swsci;
+	u32 swsci_gbda_sub_functions;
+	u32 swsci_sbcb_sub_functions;
 	struct opregion_asle __iomem *asle;
 	void __iomem *vbt;
 	u32 __iomem *lid_state;

drivers/gpu/drm/i915/intel_opregion.c

@@ -38,6 +38,9 @@
 
 #define PCI_ASLE		0xe4
 #define PCI_ASLS		0xfc
+#define PCI_SWSCI		0xe8
+#define PCI_SWSCI_SCISEL	(1 << 15)
+#define PCI_SWSCI_GSSCIE	(1 << 0)
 
 #define OPREGION_HEADER_OFFSET 0
 #define OPREGION_ACPI_OFFSET   0x100
@@ -151,6 +154,51 @@ struct opregion_asle {
 
 #define ASLE_CBLV_VALID         (1<<31)
 
+/* Software System Control Interrupt (SWSCI) */
+#define SWSCI_SCIC_INDICATOR		(1 << 0)
+#define SWSCI_SCIC_MAIN_FUNCTION_SHIFT	1
+#define SWSCI_SCIC_MAIN_FUNCTION_MASK	(0xf << 1)
+#define SWSCI_SCIC_SUB_FUNCTION_SHIFT	8
+#define SWSCI_SCIC_SUB_FUNCTION_MASK	(0xff << 8)
+#define SWSCI_SCIC_EXIT_PARAMETER_SHIFT	8
+#define SWSCI_SCIC_EXIT_PARAMETER_MASK	(0xff << 8)
+#define SWSCI_SCIC_EXIT_STATUS_SHIFT	5
+#define SWSCI_SCIC_EXIT_STATUS_MASK	(7 << 5)
+#define SWSCI_SCIC_EXIT_STATUS_SUCCESS	1
+
+#define SWSCI_FUNCTION_CODE(main, sub) \
+	((main) << SWSCI_SCIC_MAIN_FUNCTION_SHIFT | \
+	 (sub) << SWSCI_SCIC_SUB_FUNCTION_SHIFT)
+
+/* SWSCI: Get BIOS Data (GBDA) */
+#define SWSCI_GBDA			4
+#define SWSCI_GBDA_SUPPORTED_CALLS	SWSCI_FUNCTION_CODE(SWSCI_GBDA, 0)
+#define SWSCI_GBDA_REQUESTED_CALLBACKS	SWSCI_FUNCTION_CODE(SWSCI_GBDA, 1)
+#define SWSCI_GBDA_BOOT_DISPLAY_PREF	SWSCI_FUNCTION_CODE(SWSCI_GBDA, 4)
+#define SWSCI_GBDA_PANEL_DETAILS	SWSCI_FUNCTION_CODE(SWSCI_GBDA, 5)
+#define SWSCI_GBDA_TV_STANDARD		SWSCI_FUNCTION_CODE(SWSCI_GBDA, 6)
+#define SWSCI_GBDA_INTERNAL_GRAPHICS	SWSCI_FUNCTION_CODE(SWSCI_GBDA, 7)
+#define SWSCI_GBDA_SPREAD_SPECTRUM	SWSCI_FUNCTION_CODE(SWSCI_GBDA, 10)
+
+/* SWSCI: System BIOS Callbacks (SBCB) */
+#define SWSCI_SBCB			6
+#define SWSCI_SBCB_SUPPORTED_CALLBACKS	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 0)
+#define SWSCI_SBCB_INIT_COMPLETION	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 1)
+#define SWSCI_SBCB_PRE_HIRES_SET_MODE	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 3)
+#define SWSCI_SBCB_POST_HIRES_SET_MODE	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 4)
+#define SWSCI_SBCB_DISPLAY_SWITCH	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 5)
+#define SWSCI_SBCB_SET_TV_FORMAT	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 6)
+#define SWSCI_SBCB_ADAPTER_POWER_STATE	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 7)
+#define SWSCI_SBCB_DISPLAY_POWER_STATE	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 8)
+#define SWSCI_SBCB_SET_BOOT_DISPLAY	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 9)
+#define SWSCI_SBCB_SET_PANEL_DETAILS	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 10)
+#define SWSCI_SBCB_SET_INTERNAL_GFX	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 11)
+#define SWSCI_SBCB_POST_HIRES_TO_DOS_FS	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 16)
+#define SWSCI_SBCB_SUSPEND_RESUME	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 17)
+#define SWSCI_SBCB_SET_SPREAD_SPECTRUM	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 18)
+#define SWSCI_SBCB_POST_VBE_PM		SWSCI_FUNCTION_CODE(SWSCI_SBCB, 19)
+#define SWSCI_SBCB_ENABLE_DISABLE_AUDIO	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 21)
+
 #define ACPI_OTHER_OUTPUT (0<<8)
 #define ACPI_VGA_OUTPUT (1<<8)
 #define ACPI_TV_OUTPUT (2<<8)
@@ -158,6 +206,91 @@ struct opregion_asle {
 #define ACPI_LVDS_OUTPUT (4<<8)
 
 #ifdef CONFIG_ACPI
+static int swsci(struct drm_device *dev, u32 function, u32 parm, u32 *parm_out)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct opregion_swsci __iomem *swsci = dev_priv->opregion.swsci;
+	u32 main_function, sub_function, scic;
+	u16 pci_swsci;
+	u32 dslp;
+
+	if (!swsci)
+		return -ENODEV;
+
+	main_function = (function & SWSCI_SCIC_MAIN_FUNCTION_MASK) >>
+		SWSCI_SCIC_MAIN_FUNCTION_SHIFT;
+	sub_function = (function & SWSCI_SCIC_SUB_FUNCTION_MASK) >>
+		SWSCI_SCIC_SUB_FUNCTION_SHIFT;
+
+	/* Check if we can call the function. See swsci_setup for details. */
+	if (main_function == SWSCI_SBCB) {
+		if ((dev_priv->opregion.swsci_sbcb_sub_functions &
+		     (1 << sub_function)) == 0)
+			return -EINVAL;
+	} else if (main_function == SWSCI_GBDA) {
+		if ((dev_priv->opregion.swsci_gbda_sub_functions &
+		     (1 << sub_function)) == 0)
+			return -EINVAL;
+	}
+
+	/* Driver sleep timeout in ms. */
+	dslp = ioread32(&swsci->dslp);
+	if (!dslp) {
+		dslp = 2;
+	} else if (dslp > 500) {
+		/* Hey bios, trust must be earned. */
+		WARN_ONCE(1, "excessive driver sleep timeout (DSPL) %u\n", dslp);
+		dslp = 500;
+	}
+
+	/* The spec tells us to do this, but we are the only user... */
+	scic = ioread32(&swsci->scic);
+	if (scic & SWSCI_SCIC_INDICATOR) {
+		DRM_DEBUG_DRIVER("SWSCI request already in progress\n");
+		return -EBUSY;
+	}
+
+	scic = function | SWSCI_SCIC_INDICATOR;
+
+	iowrite32(parm, &swsci->parm);
+	iowrite32(scic, &swsci->scic);
+
+	/* Ensure SCI event is selected and event trigger is cleared. */
+	pci_read_config_word(dev->pdev, PCI_SWSCI, &pci_swsci);
+	if (!(pci_swsci & PCI_SWSCI_SCISEL) || (pci_swsci & PCI_SWSCI_GSSCIE)) {
+		pci_swsci |= PCI_SWSCI_SCISEL;
+		pci_swsci &= ~PCI_SWSCI_GSSCIE;
+		pci_write_config_word(dev->pdev, PCI_SWSCI, pci_swsci);
+	}
+
+	/* Use event trigger to tell bios to check the mail. */
+	pci_swsci |= PCI_SWSCI_GSSCIE;
+	pci_write_config_word(dev->pdev, PCI_SWSCI, pci_swsci);
+
+	/* Poll for the result. */
+#define C (((scic = ioread32(&swsci->scic)) & SWSCI_SCIC_INDICATOR) == 0)
+	if (wait_for(C, dslp)) {
+		DRM_DEBUG_DRIVER("SWSCI request timed out\n");
+		return -ETIMEDOUT;
+	}
+
+	scic = (scic & SWSCI_SCIC_EXIT_STATUS_MASK) >>
+		SWSCI_SCIC_EXIT_STATUS_SHIFT;
+
+	/* Note: scic == 0 is an error! */
+	if (scic != SWSCI_SCIC_EXIT_STATUS_SUCCESS) {
+		DRM_DEBUG_DRIVER("SWSCI request error %u\n", scic);
+		return -EIO;
+	}
+
+	if (parm_out)
+		*parm_out = ioread32(&swsci->parm);
+
+	return 0;
+
+#undef C
+}
+
 static u32 asle_set_backlight(struct drm_device *dev, u32 bclp)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -447,7 +580,66 @@ void intel_opregion_fini(struct drm_device *dev)
 	opregion->asle = NULL;
 	opregion->vbt = NULL;
 }
-#endif
+
+static void swsci_setup(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_opregion *opregion = &dev_priv->opregion;
+	bool requested_callbacks = false;
+	u32 tmp;
+
+	/* Sub-function code 0 is okay, let's allow them. */
+	opregion->swsci_gbda_sub_functions = 1;
+	opregion->swsci_sbcb_sub_functions = 1;
+
+	/* We use GBDA to ask for supported GBDA calls. */
+	if (swsci(dev, SWSCI_GBDA_SUPPORTED_CALLS, 0, &tmp) == 0) {
+		/* make the bits match the sub-function codes */
+		tmp <<= 1;
+		opregion->swsci_gbda_sub_functions |= tmp;
+	}
+
+	/*
+	 * We also use GBDA to ask for _requested_ SBCB callbacks. The driver
+	 * must not call interfaces that are not specifically requested by the
+	 * bios.
+	 */
+	if (swsci(dev, SWSCI_GBDA_REQUESTED_CALLBACKS, 0, &tmp) == 0) {
+		/* here, the bits already match sub-function codes */
+		opregion->swsci_sbcb_sub_functions |= tmp;
+		requested_callbacks = true;
+	}
+
+	/*
+	 * But we use SBCB to ask for _supported_ SBCB calls. This does not mean
+	 * the callback is _requested_. But we still can't call interfaces that
+	 * are not requested.
+	 */
+	if (swsci(dev, SWSCI_SBCB_SUPPORTED_CALLBACKS, 0, &tmp) == 0) {
+		/* make the bits match the sub-function codes */
+		u32 low = tmp & 0x7ff;
+		u32 high = tmp & ~0xfff; /* bit 11 is reserved */
+		tmp = (high << 4) | (low << 1) | 1;
+
+		/* best guess what to do with supported wrt requested */
+		if (requested_callbacks) {
+			u32 req = opregion->swsci_sbcb_sub_functions;
+			if ((req & tmp) != req)
+				DRM_DEBUG_DRIVER("SWSCI BIOS requested (%08x) SBCB callbacks that are not supported (%08x)\n", req, tmp);
+			/* XXX: for now, trust the requested callbacks */
+			/* opregion->swsci_sbcb_sub_functions &= tmp; */
+		} else {
+			opregion->swsci_sbcb_sub_functions |= tmp;
+		}
+	}
+
+	DRM_DEBUG_DRIVER("SWSCI GBDA callbacks %08x, SBCB callbacks %08x\n",
+			 opregion->swsci_gbda_sub_functions,
+			 opregion->swsci_sbcb_sub_functions);
+}
+#else /* CONFIG_ACPI */
+static inline void swsci_setup(struct drm_device *dev) {}
+#endif  /* CONFIG_ACPI */
 
 int intel_opregion_setup(struct drm_device *dev)
 {
@@ -490,6 +682,7 @@ int intel_opregion_setup(struct drm_device *dev)
 	if (mboxes & MBOX_SWSCI) {
 		DRM_DEBUG_DRIVER("SWSCI supported\n");
 		opregion->swsci = base + OPREGION_SWSCI_OFFSET;
+		swsci_setup(dev);
 	}
 	if (mboxes & MBOX_ASLE) {
 		DRM_DEBUG_DRIVER("ASLE supported\n");