[PATCH] ACPI: Parse entire table as a term_list for Dell XPS 9570 and Precision M5530

[Kai-Heng Feng <kai.heng.feng@canonical.com>]

The i2c touchpad on Dell XPS 9570 and Precision M5530 doesn't work out
of box.

The touchpad relies on its _INI method to update its _HID value from
XXXX0000 to SYNA2393.
Also, the _STA relies on value of I2CN to report correct status.

Set acpi_gbl_parse_table_as_term_list so the value of I2CN can be
correctly set up, and _INI can get run. The ACPI table in this machine
is designed to get parsed this way.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=198515
Cc: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 drivers/acpi/bus.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 4d0979e02a28..4da34d67e23d 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -88,6 +86,45 @@ static const struct dmi_system_id dsdt_dmi_table[] __initconst = {
 };
 #endif
 
+#ifdef CONFIG_X86
+static int set_gbl_term_list(const struct dmi_system_id *id)
+{
+	pr_notice("%s detected - parse the entire table as a term_list\n",
+		  id->ident);
+	acpi_gbl_parse_table_as_term_list = 1;
+	return 0;
+}
+
+static const struct dmi_system_id gbl_term_list_dmi_table[] __initconst = {
+	/*
+	 * Touchpad on Dell XPS 9570/Precision M5530 doesn't work under I2C
+	 * mode.
+	 * https://bugzilla.kernel.org/show_bug.cgi?id=198515
+	 */
+	{
+		.callback = set_gbl_term_list,
+		.ident = "Dell Precision M5530",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Precision M5530"),
+		},
+	},
+	{
+		.callback = set_gbl_term_list,
+		.ident = "Dell XPS 15 9570",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "XPS 15 9570"),
+		},
+	},
+	{}
+};
+#else
+static const struct dmi_system_id gbl_term_list_dmi_table[] __initconst = {
+	{}
+};
+#endif
+
 /* --------------------------------------------------------------------------
                                 Device Management
    -------------------------------------------------------------------------- */
@@ -1007,6 +1046,8 @@ void __init acpi_early_init(void)
 	 */
 	dmi_check_system(dsdt_dmi_table);
 
+	dmi_check_system(gbl_term_list_dmi_table);
+
 	status = acpi_reallocate_root_table();
 	if (ACPI_FAILURE(status)) {
 		printk(KERN_ERR PREFIX
-- 
2.15.1