acpi: Add a function to get a device path and scope

Add a function to build up the ACPI path for a device and another for its
scope.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

arch/sandbox/dts/test.dts

@@ -255,6 +255,9 @@
 
 	acpi-test {
 		compatible = "denx,u-boot-acpi-test";
+		child {
+			compatible = "denx,u-boot-acpi-test";
+		};
 	};
 
 	acpi-test2 {

include/acpi/acpi_device.h

@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Generation of tables for particular device types
+ *
+ * Copyright 2019 Google LLC
+ * Mostly taken from coreboot file of the same name
+ */
+
+#ifndef __ACPI_DEVICE_H
+#define __ACPI_DEVICE_H
+
+struct udevice;
+
+/* Length of a full path to an ACPI device */
+#define ACPI_PATH_MAX		30
+
+/**
+ * acpi_device_path() - Get the full path to an ACPI device
+ *
+ * This gets the full path in the form XXXX.YYYY.ZZZZ where XXXX is the root
+ * and ZZZZ is the device. All parent devices are added to the path.
+ *
+ * @dev: Device to check
+ * @buf: Buffer to place the path in (should be ACPI_PATH_MAX long)
+ * @maxlen: Size of buffer (typically ACPI_PATH_MAX)
+ * @return 0 if OK, -ve on error
+ */
+int acpi_device_path(const struct udevice *dev, char *buf, int maxlen);
+
+/**
+ * acpi_device_scope() - Get the scope of an ACPI device
+ *
+ * This gets the scope which is the full path of the parent device, as per
+ * acpi_device_path().
+ *
+ * @dev: Device to check
+ * @buf: Buffer to place the path in (should be ACPI_PATH_MAX long)
+ * @maxlen: Size of buffer (typically ACPI_PATH_MAX)
+ * @return 0 if OK, -EINVAL if the device has no parent, other -ve on other
+ *	error
+ */
+int acpi_device_scope(const struct udevice *dev, char *scope, int maxlen);
+
+#endif

lib/acpi/Makefile

@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0+
 #
 
+obj-y += acpi_device.o
 obj-y += acpi_table.o

lib/acpi/acpi_device.c

@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generation of tables for particular device types
+ *
+ * Copyright 2019 Google LLC
+ * Mostly taken from coreboot file of the same name
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <log.h>
+#include <acpi/acpi_device.h>
+#include <dm/acpi.h>
+
+/**
+ * acpi_device_path_fill() - Find the root device and build a path from there
+ *
+ * This recursively reaches back to the root device and progressively adds path
+ * elements until the device is reached.
+ *
+ * @dev: Device to return path of
+ * @buf: Buffer to hold the path
+ * @buf_len: Length of buffer
+ * @cur: Current position in the buffer
+ * @return new position in buffer after adding @dev, or -ve on error
+ */
+static int acpi_device_path_fill(const struct udevice *dev, char *buf,
+				 size_t buf_len, int cur)
+{
+	char name[ACPI_NAME_MAX];
+	int next = 0;
+	int ret;
+
+	ret = acpi_get_name(dev, name);
+	if (ret)
+		return ret;
+
+	/*
+	 * Make sure this name segment will fit, including the path segment
+	 * separator and possible NULL terminator, if this is the last segment.
+	 */
+	if (cur + strlen(name) + 2 > buf_len)
+		return -ENOSPC;
+
+	/* Walk up the tree to the root device */
+	if (dev_get_parent(dev)) {
+		next = acpi_device_path_fill(dev_get_parent(dev), buf, buf_len,
+					     cur);
+		if (next < 0)
+			return next;
+	}
+
+	/* Fill in the path from the root device */
+	next += snprintf(buf + next, buf_len - next, "%s%s",
+			 dev_get_parent(dev) && *name ? "." : "", name);
+
+	return next;
+}
+
+int acpi_device_path(const struct udevice *dev, char *buf, int maxlen)
+{
+	int ret;
+
+	ret = acpi_device_path_fill(dev, buf, maxlen, 0);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+int acpi_device_scope(const struct udevice *dev, char *scope, int maxlen)
+{
+	int ret;
+
+	if (!dev_get_parent(dev))
+		return log_msg_ret("noparent", -EINVAL);
+
+	ret = acpi_device_path_fill(dev_get_parent(dev), scope, maxlen, 0);
+	if (ret < 0)
+		return log_msg_ret("fill", ret);
+
+	return 0;
+}

test/dm/acpi.c

@@ -14,14 +14,27 @@
 #include <version.h>
 #include <tables_csum.h>
 #include <version.h>
+#include <acpi/acpi_device.h>
 #include <acpi/acpi_table.h>
 #include <dm/acpi.h>
 #include <dm/test.h>
 #include <test/ut.h>
 
 #define ACPI_TEST_DEV_NAME	"ABCD"
+#define ACPI_TEST_CHILD_NAME	"EFGH"
 #define BUF_SIZE		4096
 
+/**
+ * struct testacpi_platdata - Platform data for the test ACPI device
+ *
+ * @no_name: true to emit an empty ACPI name from testacpi_get_name()
+ * @return_error: true to return an error instead of a name
+ */
+struct testacpi_platdata {
+	bool return_error;
+	bool no_name;
+};
+
 static int testacpi_write_tables(const struct udevice *dev,
 				 struct acpi_ctx *ctx)
 {
@@ -40,7 +53,18 @@ static int testacpi_write_tables(const struct udevice *dev,
 
 static int testacpi_get_name(const struct udevice *dev, char *out_name)
 {
-	return acpi_copy_name(out_name, ACPI_TEST_DEV_NAME);
+	struct testacpi_platdata *plat = dev_get_platdata(dev);
+
+	if (plat->return_error)
+		return -EINVAL;
+	if (plat->no_name) {
+		*out_name = '\0';
+		return 0;
+	}
+	if (device_get_uclass_id(dev->parent) == UCLASS_TEST_ACPI)
+		return acpi_copy_name(out_name, ACPI_TEST_CHILD_NAME);
+	else
+		return acpi_copy_name(out_name, ACPI_TEST_DEV_NAME);
 }
 
 struct acpi_ops testacpi_ops = {
@@ -57,6 +81,8 @@ U_BOOT_DRIVER(testacpi_drv) = {
 	.name	= "testacpi_drv",
 	.of_match	= testacpi_ids,
 	.id	= UCLASS_TEST_ACPI,
+	.bind	= dm_scan_fdt_dev,
+	.platdata_auto_alloc_size	= sizeof(struct testacpi_platdata),
 	ACPI_OPS_PTR(&testacpi_ops)
 };
 
@@ -138,6 +164,7 @@ static int dm_test_acpi_write_tables(struct unit_test_state *uts)
 	struct acpi_dmar *dmar;
 	struct acpi_ctx ctx;
 	void *buf;
+	int i;
 
 	buf = malloc(BUF_SIZE);
 	ut_assertnonnull(buf);
@@ -147,24 +174,26 @@ static int dm_test_acpi_write_tables(struct unit_test_state *uts)
 	ut_assertok(acpi_write_dev_tables(&ctx));
 
 	/*
-	 * We should have two dmar tables, one for each "denx,u-boot-acpi-test"
-	 * device
+	 * We should have three dmar tables, one for each
+	 * "denx,u-boot-acpi-test" device
 	 */
-	ut_asserteq_ptr(dmar + 2, ctx.current);
+	ut_asserteq_ptr(dmar + 3, ctx.current);
 	ut_asserteq(DMAR_INTR_REMAP, dmar->flags);
 	ut_asserteq(32 - 1, dmar->host_address_width);
 
 	ut_asserteq(DMAR_INTR_REMAP, dmar[1].flags);
 	ut_asserteq(32 - 1, dmar[1].host_address_width);
 
-	/* Check that the pointers were added correctly */
-	ut_asserteq(map_to_sysmem(dmar), ctx.rsdt->entry[0]);
-	ut_asserteq(map_to_sysmem(dmar + 1), ctx.rsdt->entry[1]);
-	ut_asserteq(0, ctx.rsdt->entry[2]);
+	ut_asserteq(DMAR_INTR_REMAP, dmar[2].flags);
+	ut_asserteq(32 - 1, dmar[2].host_address_width);
 
-	ut_asserteq(map_to_sysmem(dmar), ctx.xsdt->entry[0]);
-	ut_asserteq(map_to_sysmem(dmar + 1), ctx.xsdt->entry[1]);
-	ut_asserteq(0, ctx.xsdt->entry[2]);
+	/* Check that the pointers were added correctly */
+	for (i = 0; i < 3; i++) {
+		ut_asserteq(map_to_sysmem(dmar + i), ctx.rsdt->entry[i]);
+		ut_asserteq(map_to_sysmem(dmar + i), ctx.xsdt->entry[i]);
+	}
+	ut_asserteq(0, ctx.rsdt->entry[3]);
+	ut_asserteq(0, ctx.xsdt->entry[3]);
 
 	return 0;
 }
@@ -268,15 +297,18 @@ static int dm_test_acpi_cmd_list(struct unit_test_state *uts)
 	addr = ALIGN(addr + sizeof(struct acpi_rsdp), 16);
 	ut_assert_nextline("RSDT %08lx %06lx (v01 U-BOOT U-BOOTBL %u INTL 0)",
 			   addr, sizeof(struct acpi_table_header) +
-			   2 * sizeof(u32), U_BOOT_BUILD_DATE);
+			   3 * sizeof(u32), U_BOOT_BUILD_DATE);
 	addr = ALIGN(addr + sizeof(struct acpi_rsdt), 16);
 	ut_assert_nextline("XSDT %08lx %06lx (v01 U-BOOT U-BOOTBL %u INTL 0)",
 			   addr, sizeof(struct acpi_table_header) +
-			   2 * sizeof(u64), U_BOOT_BUILD_DATE);
+			   3 * sizeof(u64), U_BOOT_BUILD_DATE);
 	addr = ALIGN(addr + sizeof(struct acpi_xsdt), 64);
 	ut_assert_nextline("DMAR %08lx %06lx (v01 U-BOOT U-BOOTBL %u INTL 0)",
 			   addr, sizeof(struct acpi_dmar), U_BOOT_BUILD_DATE);
 	addr = ALIGN(addr + sizeof(struct acpi_dmar), 16);
+	ut_assert_nextline("DMAR %08lx %06lx (v01 U-BOOT U-BOOTBL %u INTL 0)",
+			   addr, sizeof(struct acpi_dmar), U_BOOT_BUILD_DATE);
+	addr = ALIGN(addr + sizeof(struct acpi_dmar), 16);
 	ut_assert_nextline("DMAR %08lx %06lx (v01 U-BOOT U-BOOTBL %u INTL 0)",
 			   addr, sizeof(struct acpi_dmar), U_BOOT_BUILD_DATE);
 	ut_assert_console_end();
@@ -315,3 +347,40 @@ static int dm_test_acpi_cmd_dump(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_acpi_cmd_dump, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test acpi_device_path() */
+static int dm_test_acpi_device_path(struct unit_test_state *uts)
+{
+	struct testacpi_platdata *plat;
+	char buf[ACPI_PATH_MAX];
+	struct udevice *dev, *child;
+
+	ut_assertok(uclass_first_device_err(UCLASS_TEST_ACPI, &dev));
+	ut_assertok(acpi_device_path(dev, buf, sizeof(buf)));
+	ut_asserteq_str("\\_SB." ACPI_TEST_DEV_NAME, buf);
+
+	/* Test running out of space */
+	buf[5] = '\0';
+	ut_asserteq(-ENOSPC, acpi_device_path(dev, buf, 5));
+	ut_asserteq('\0', buf[5]);
+
+	/* Test a three-component name */
+	ut_assertok(device_first_child_err(dev, &child));
+	ut_assertok(acpi_device_path(child, buf, sizeof(buf)));
+	ut_asserteq_str("\\_SB." ACPI_TEST_DEV_NAME "." ACPI_TEST_CHILD_NAME,
+			buf);
+
+	/* Test handling of a device which doesn't produce a name */
+	plat = dev_get_platdata(dev);
+	plat->no_name = true;
+	ut_assertok(acpi_device_path(child, buf, sizeof(buf)));
+	ut_asserteq_str("\\_SB." ACPI_TEST_CHILD_NAME, buf);
+
+	/* Test handling of a device which returns an error */
+	plat = dev_get_platdata(dev);
+	plat->return_error = true;
+	ut_asserteq(-EINVAL, acpi_device_path(child, buf, sizeof(buf)));
+
+	return 0;
+}
+DM_TEST(dm_test_acpi_device_path, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);