linux-kernel - [PATCH 5/6] platform/chrome: cros_ec_lpc: Correct ACPI name for Framework Laptop

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Date: Wed, 15 May 2024 06:56:30 +0100
From: Ben Walsh <ben@...nut.com>
To: Benson Leung <bleung@...omium.org>,
	Tzung-Bi Shih <tzungbi@...nel.org>,
	Guenter Roeck <groeck@...omium.org>,
	"Dustin L. Howett" <dustin@...ett.net>,
	Kieran Levin <ktl@...me.work>,
	Thomas Weißschuh <linux@...ssschuh.net>,
	Mario Limonciello <mario.limonciello@....com>,
	chrome-platform@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Cc: Ben Walsh <ben@...nut.com>
Subject: [PATCH 5/6] platform/chrome: cros_ec_lpc: Correct ACPI name for Framework Laptop

Framework Laptops' ACPI exposes the EC as name "PNP0C09". Use this to
find the device. This makes it easy to find the AML mutex via the
ACPI_COMPANION device.

The name "PNP0C09" is part of the ACPI standard, not Chrome-specific,
so only recognise the device if the DMI data is recognised too.

Signed-off-by: Ben Walsh <ben@...nut.com>
---
 drivers/platform/chrome/cros_ec_lpc.c | 38 ++++++++++++++++-----------
 1 file changed, 22 insertions(+), 16 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
index ab7779b57a13..a9200f0a1a37 100644
--- a/drivers/platform/chrome/cros_ec_lpc.c
+++ b/drivers/platform/chrome/cros_ec_lpc.c
@@ -29,10 +29,12 @@
 #include "cros_ec_lpc_mec.h"
 
 #define DRV_NAME "cros_ec_lpcs"
-#define ACPI_DRV_NAME "GOOG0004"
 
-/* True if ACPI device is present */
-static bool cros_ec_lpc_acpi_device_found;
+/*
+ * Index into cros_ec_lpc_acpi_device_ids of ACPI device,
+ * negative for ACPI device not found.
+ */
+static int cros_ec_lpc_acpi_device_found;
 
 /*
  * Indicates that lpc_driver_data.quirk_mmio_memory_base should
@@ -598,7 +600,8 @@ static void cros_ec_lpc_remove(struct platform_device *pdev)
 }
 
 static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
-	{ ACPI_DRV_NAME, 0 },
+	{ "PNP0C09", 0 },    /* Standard ACPI EC name. Must be first in list */
+	{ "GOOG0004", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(acpi, cros_ec_lpc_acpi_device_ids);
@@ -737,30 +740,33 @@ static struct platform_device cros_ec_lpc_device = {
 	.name = DRV_NAME
 };
 
-static acpi_status cros_ec_lpc_parse_device(acpi_handle handle, u32 level,
-					    void *context, void **retval)
+static int cros_ec_lpc_find_acpi_dev(const struct acpi_device_id *acpi_ids)
 {
-	*(bool *)context = true;
-	return AE_CTRL_TERMINATE;
+	int i;
+
+	for (i = 0; acpi_ids[i].id[0]; ++i) {
+		if (acpi_dev_present(acpi_ids[i].id, NULL, -1))
+			return i;
+	}
+
+	return -1;
 }
 
 static int __init cros_ec_lpc_init(void)
 {
 	int ret;
-	acpi_status status;
 	const struct dmi_system_id *dmi_match;
 
-	status = acpi_get_devices(ACPI_DRV_NAME, cros_ec_lpc_parse_device,
-				  &cros_ec_lpc_acpi_device_found, NULL);
-	if (ACPI_FAILURE(status))
-		pr_warn(DRV_NAME ": Looking for %s failed\n", ACPI_DRV_NAME);
+	cros_ec_lpc_acpi_device_found = cros_ec_lpc_find_acpi_dev(
+		cros_ec_lpc_driver.driver.acpi_match_table);
 
 	dmi_match = dmi_first_match(cros_ec_lpc_dmi_table);
 
 	if (dmi_match) {
 		/* Pass the DMI match's driver data down to the platform device */
 		cros_ec_lpc_driver_data = dmi_match->driver_data;
-	} else if (!cros_ec_lpc_acpi_device_found) {
+	} else if (cros_ec_lpc_acpi_device_found <= 0) {
+		/* Standard EC "PNP0C09" not supported without DMI data */
 		pr_err(DRV_NAME ": unsupported system.\n");
 		return -ENODEV;
 	}
@@ -772,7 +778,7 @@ static int __init cros_ec_lpc_init(void)
 		return ret;
 	}
 
-	if (!cros_ec_lpc_acpi_device_found) {
+	if (cros_ec_lpc_acpi_device_found < 0) {
 		/* Register the device, and it'll get hooked up automatically */
 		ret = platform_device_register(&cros_ec_lpc_device);
 		if (ret) {
@@ -786,7 +792,7 @@ static int __init cros_ec_lpc_init(void)
 
 static void __exit cros_ec_lpc_exit(void)
 {
-	if (!cros_ec_lpc_acpi_device_found)
+	if (cros_ec_lpc_acpi_device_found < 0)
 		platform_device_unregister(&cros_ec_lpc_device);
 	platform_driver_unregister(&cros_ec_lpc_driver);
 }
-- 
2.45.0