[PATCH 1/1] UBUNTU: SAUCE: mfd: intel-lpss: add quirk for Dell XPS 13 7390 2-in-1

[AceLan Kao]

BugLink: https://bugs.launchpad.net/bugs/1845584

The memory region intel-lpss-pci uses has been declared as
write-combining
[    0.001728]   5 base 4000000000 mask 6000000000 write-combining
This leads to the system hangs up during booting up.

Tuowen Zhao(ztuowen at gmail.com) provides a diff patch for intel-lpss
driver to claim to use un-cacheable memory while calling
__devm_ioremap(), and it works well. But it haven't been accepted by
maintainer yet.

To avoid the potential impact on other machines, I add a quirk to list
the machines which has the write-combining area in MTRR which overlaps
with the address that intel-lpss uses, only the machines in the list
pass the DEVM_IOREMAP_UC to __devm_ioremap().

Link: https://bugzilla.kernel.org/show_bug.cgi?id=203485
Signed-off-by: AceLan Kao <acelan.kao at canonical.com>
---
 drivers/mfd/intel-lpss.c | 20 ++++++++++++++++++--
 include/linux/io.h       |  2 ++
 lib/devres.c             | 20 ++++++++++++++++++++
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c
index 277f48f1cc1c..5223aba7ba1d 100644
--- a/drivers/mfd/intel-lpss.c
+++ b/drivers/mfd/intel-lpss.c
@@ -14,6 +14,7 @@
 #include <linux/clkdev.h>
 #include <linux/clk-provider.h>
 #include <linux/debugfs.h>
+#include <linux/dmi.h>
 #include <linux/idr.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
@@ -128,6 +129,17 @@ static const struct mfd_cell intel_lpss_spi_cell = {
 static DEFINE_IDA(intel_lpss_devid_ida);
 static struct dentry *intel_lpss_debugfs;
 
+static const struct dmi_system_id mtrr_large_wc_region[] = {
+	{
+		.ident = "Dell Computer Corporation",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "XPS 13 7390 2-in-1"),
+		},
+	},
+	{ }
+};
+
 static int intel_lpss_request_dma_module(const char *name)
 {
 	static bool intel_lpss_dma_requested;
@@ -395,8 +407,12 @@ int intel_lpss_probe(struct device *dev,
 	if (!lpss)
 		return -ENOMEM;
 
-	lpss->priv = devm_ioremap(dev, info->mem->start + LPSS_PRIV_OFFSET,
-				  LPSS_PRIV_SIZE);
+	if (dmi_check_system(mtrr_large_wc_region))
+		lpss->priv = devm_ioremap_uc(dev, info->mem->start + LPSS_PRIV_OFFSET,
+					     LPSS_PRIV_SIZE);
+	else
+		lpss->priv = devm_ioremap(dev, info->mem->start + LPSS_PRIV_OFFSET,
+					  LPSS_PRIV_SIZE);
 	if (!lpss->priv)
 		return -ENOMEM;
 
diff --git a/include/linux/io.h b/include/linux/io.h
index accac822336a..a59834bc0a11 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -64,6 +64,8 @@ static inline void devm_ioport_unmap(struct device *dev, void __iomem *addr)
 
 void __iomem *devm_ioremap(struct device *dev, resource_size_t offset,
 			   resource_size_t size);
+void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
+				   resource_size_t size);
 void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
 				   resource_size_t size);
 void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
diff --git a/lib/devres.c b/lib/devres.c
index 6a0e9bd6524a..ca4a18f71798 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -9,6 +9,7 @@
 enum devm_ioremap_type {
 	DEVM_IOREMAP = 0,
 	DEVM_IOREMAP_NC,
+	DEVM_IOREMAP_UC,
 	DEVM_IOREMAP_WC,
 };
 
@@ -39,6 +40,9 @@ static void __iomem *__devm_ioremap(struct device *dev, resource_size_t offset,
 	case DEVM_IOREMAP_NC:
 		addr = ioremap_nocache(offset, size);
 		break;
+	case DEVM_IOREMAP_UC:
+		addr = ioremap_uc(offset, size);
+		break;
 	case DEVM_IOREMAP_WC:
 		addr = ioremap_wc(offset, size);
 		break;
@@ -68,6 +72,22 @@ void __iomem *devm_ioremap(struct device *dev, resource_size_t offset,
 }
 EXPORT_SYMBOL(devm_ioremap);
 
+/**
+ * devm_ioremap_uc - Managed ioremap_uc()
+ * @dev: Generic device to remap IO address for
+ * @offset: Resource address to map
+ * @size: Size of map
+ *
+ * Managed ioremap_uc().  Map is automatically unmapped on driver detach.
+ */
+void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
+			      resource_size_t size)
+{
+	return __devm_ioremap(dev, offset, size, DEVM_IOREMAP_UC);
+}
+EXPORT_SYMBOL(devm_ioremap_uc);
+
+
 /**
  * devm_ioremap_nocache - Managed ioremap_nocache()
  * @dev: Generic device to remap IO address for
-- 
2.17.1