3 files changed, 87 insertions, 5 deletions

diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
index 8c2bae980fa..69e29f409d4 100644
--- a/drivers/acpi/acpi_lpss.c
+++ b/drivers/acpi/acpi_lpss.c
@@ -33,6 +33,13 @@ ACPI_MODULE_NAME("acpi_lpss");
 #define LPSS_GENERAL_UART_RTS_OVRD	BIT(3)
 #define LPSS_SW_LTR			0x10
 #define LPSS_AUTO_LTR			0x14
+#define LPSS_LTR_SNOOP_REQ		BIT(15)
+#define LPSS_LTR_SNOOP_MASK		0x0000FFFF
+#define LPSS_LTR_SNOOP_LAT_1US		0x800
+#define LPSS_LTR_SNOOP_LAT_32US		0xC00
+#define LPSS_LTR_SNOOP_LAT_SHIFT	5
+#define LPSS_LTR_SNOOP_LAT_CUTOFF	3000
+#define LPSS_LTR_MAX_VAL		0x3FF
 #define LPSS_TX_INT			0x20
 #define LPSS_TX_INT_MASK		BIT(1)
 
@@ -326,6 +333,17 @@ static int acpi_lpss_create_device(struct acpi_device *adev,
 	return ret;
 }
 
+static u32 __lpss_reg_read(struct lpss_private_data *pdata, unsigned int reg)
+{
+	return readl(pdata->mmio_base + pdata->dev_desc->prv_offset + reg);
+}
+
+static void __lpss_reg_write(u32 val, struct lpss_private_data *pdata,
+			     unsigned int reg)
+{
+	writel(val, pdata->mmio_base + pdata->dev_desc->prv_offset + reg);
+}
+
 static int lpss_reg_read(struct device *dev, unsigned int reg, u32 *val)
 {
 	struct acpi_device *adev;
@@ -347,7 +365,7 @@ static int lpss_reg_read(struct device *dev, unsigned int reg, u32 *val)
 		ret = -ENODEV;
 		goto out;
 	}
-	*val = readl(pdata->mmio_base + pdata->dev_desc->prv_offset + reg);
+	*val = __lpss_reg_read(pdata, reg);
 
  out:
 	spin_unlock_irqrestore(&dev->power.lock, flags);
@@ -400,6 +418,37 @@ static struct attribute_group lpss_attr_group = {
 	.name = "lpss_ltr",
 };
 
+static void acpi_lpss_set_ltr(struct device *dev, s32 val)
+{
+	struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));
+	u32 ltr_mode, ltr_val;
+
+	ltr_mode = __lpss_reg_read(pdata, LPSS_GENERAL);
+	if (val < 0) {
+		if (ltr_mode & LPSS_GENERAL_LTR_MODE_SW) {
+			ltr_mode &= ~LPSS_GENERAL_LTR_MODE_SW;
+			__lpss_reg_write(ltr_mode, pdata, LPSS_GENERAL);
+		}
+		return;
+	}
+	ltr_val = __lpss_reg_read(pdata, LPSS_SW_LTR) & ~LPSS_LTR_SNOOP_MASK;
+	if (val >= LPSS_LTR_SNOOP_LAT_CUTOFF) {
+		ltr_val |= LPSS_LTR_SNOOP_LAT_32US;
+		val = LPSS_LTR_MAX_VAL;
+	} else if (val > LPSS_LTR_MAX_VAL) {
+		ltr_val |= LPSS_LTR_SNOOP_LAT_32US | LPSS_LTR_SNOOP_REQ;
+		val >>= LPSS_LTR_SNOOP_LAT_SHIFT;
+	} else {
+		ltr_val |= LPSS_LTR_SNOOP_LAT_1US | LPSS_LTR_SNOOP_REQ;
+	}
+	ltr_val |= val;
+	__lpss_reg_write(ltr_val, pdata, LPSS_SW_LTR);
+	if (!(ltr_mode & LPSS_GENERAL_LTR_MODE_SW)) {
+		ltr_mode |= LPSS_GENERAL_LTR_MODE_SW;
+		__lpss_reg_write(ltr_mode, pdata, LPSS_GENERAL);
+	}
+}
+
 static int acpi_lpss_platform_notify(struct notifier_block *nb,
 				     unsigned long action, void *data)
 {
@@ -437,9 +486,29 @@ static struct notifier_block acpi_lpss_nb = {
 	.notifier_call = acpi_lpss_platform_notify,
 };
 
+static void acpi_lpss_bind(struct device *dev)
+{
+	struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));
+
+	if (!pdata || !pdata->mmio_base || !pdata->dev_desc->ltr_required)
+		return;
+
+	if (pdata->mmio_size >= pdata->dev_desc->prv_offset + LPSS_LTR_SIZE)
+		dev->power.set_latency_tolerance = acpi_lpss_set_ltr;
+	else
+		dev_err(dev, "MMIO size insufficient to access LTR\n");
+}
+
+static void acpi_lpss_unbind(struct device *dev)
+{
+	dev->power.set_latency_tolerance = NULL;
+}
+
 static struct acpi_scan_handler lpss_handler = {
 	.ids = acpi_lpss_device_ids,
 	.attach = acpi_lpss_create_device,
+	.bind = acpi_lpss_bind,
+	.unbind = acpi_lpss_unbind,
 };
 
 void __init acpi_lpss_init(void)
diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index 0c789224d40..f774c65ecb8 100644
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -287,6 +287,7 @@ EXPORT_SYMBOL_GPL(acpi_unbind_one);
 static int acpi_platform_notify(struct device *dev)
 {
 	struct acpi_bus_type *type = acpi_get_bus_type(dev);
+	struct acpi_device *adev;
 	int ret;
 
 	ret = acpi_bind_one(dev, NULL);
@@ -303,9 +304,14 @@ static int acpi_platform_notify(struct device *dev)
 		if (ret)
 			goto out;
 	}
+	adev = ACPI_COMPANION(dev);
+	if (!adev)
+		goto out;
 
 	if (type && type->setup)
 		type->setup(dev);
+	else if (adev->handler && adev->handler->bind)
+		adev->handler->bind(dev);
 
  out:
 #if ACPI_GLUE_DEBUG
@@ -324,11 +330,17 @@ static int acpi_platform_notify(struct device *dev)
 
 static int acpi_platform_notify_remove(struct device *dev)
 {
+	struct acpi_device *adev = ACPI_COMPANION(dev);
 	struct acpi_bus_type *type;
 
+	if (!adev)
+		return 0;
+
 	type = acpi_get_bus_type(dev);
 	if (type && type->cleanup)
 		type->cleanup(dev);
+	else if (adev->handler && adev->handler->unbind)
+		adev->handler->unbind(dev);
 
 	acpi_unbind_one(dev);
 	return 0;
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 1870223cb1a..7efe546a8c4 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2072,13 +2072,14 @@ static int acpi_scan_attach_handler(struct acpi_device *device)
 
 		handler = acpi_scan_match_handler(hwid->id, &devid);
 		if (handler) {
+			device->handler = handler;
 			ret = handler->attach(device, devid);
-			if (ret > 0) {
-				device->handler = handler;
+			if (ret > 0)
 				break;
-			} else if (ret < 0) {
+
+			device->handler = NULL;
+			if (ret < 0)
 				break;
-			}
 		}
 	}
 	return ret;