acpi: Be more ACPI compliant when generating _UID

* Add function to generate unique _UID using CRC32
* Add function to write the _UID based on a device's ACPI path

ACPI devices that have the same _HID must use different _UID.
Linux doesn't care about _UID if it's not used.
Windows 10 verifies the ACPI code on boot and BSODs if two devices
with the same _HID share the same _UID.

Fixes BSOD seen on Windows 10.

Change-Id: I47cd5396060d325f9ce338afced6af021e7ff2b4
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37695
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>

src/arch/x86/acpi_device.c

@@ -18,6 +18,8 @@
 #include <device/device.h>
 #include <device/path.h>
 #include <stdlib.h>
+#include <crc_byte.h>
+
 #if CONFIG(GENERIC_GPIO_LIB)
 #include <gpio.h>
 #endif
@@ -98,6 +100,19 @@ const char *acpi_device_hid(const struct device *dev)
 	return NULL;
 }
 
+/*
+ * Generate unique ID based on the ACPI path.
+ * Collisions on the same _HID are possible but very unlikely.
+ */
+uint32_t acpi_device_uid(struct device *dev)
+{
+	const char *path = acpi_device_path(dev);
+	if (!path)
+		return 0;
+
+	return CRC(path, strlen(path), crc32_byte);
+}
+
 /* Recursive function to find the root device and print a path from there */
 static ssize_t acpi_device_path_fill(const struct device *dev, char *buf,
 				     size_t buf_len, size_t cur)
@@ -192,6 +207,13 @@ int acpi_device_status(const struct device *dev)
 	return ACPI_STATUS_DEVICE_ALL_ON;
 }
 
+
+/* Write the unique _UID based on ACPI device path. */
+void acpi_device_write_uid(struct device *dev)
+{
+	acpigen_write_name_integer("_UID", acpi_device_uid(dev));
+}
+
 /* ACPI 6.1 section 6.4.3.6: Extended Interrupt Descriptor */
 void acpi_device_write_interrupt(const struct acpi_irq *irq)
 {