platform/x86: lg-laptop: Add operation region support

The LEGX0820 ACPI device is expected to provide a custom operation
region:

	OperationRegion (XIN1, 0x8F, Zero, 0x04B0)
        Field (XIN1, AnyAcc, Lock, Preserve)
        {
            DMSG,   8,
            HDAP,   8,
            Offset (0x03),
            AFNM,   8,
            Offset (0x10),
            P80B,   8,
            P81B,   8,
            P82B,   8,
            P83B,   8,
            P84B,   8,
            P85B,   8,
            P86B,   8,
            P87B,   8,
            Offset (0x20),
            DTTM,   8,
            TMP1,   8,
            LTP1,   8,
            HTP1,   8,
            TMP2,   8,
            LTP2,   8,
            HTP2,   8,
            Offset (0x3E8),
            PMSG,   1600
        }

The PMSG field is used by AML code to log debug messages when DMSG is
true. Since those debug messages are already logged using the standard
ACPI Debug object, we set DMSG unconditionally to 0x00 and ignore any
writes to PMSG.

The TMPx, LTPx, HTPx and AFNM fields are used to inform the driver when
the temperature/(presumably) trip points/fan mode changes. This only
happens when the DTTM flag is set.

Unfortunately we have to implement support for this operation region
because the AML codes uses code constructs like this one:

	If (((\_SB.XINI.PLAV != Zero) && (\_SB.XINI.DTTM != Zero)))

The PLAV field gets set to 1 when the driver registers its address space
handler, so by default XIN1 should not be accessed.

However ACPI does not use short-circuit evaluation when evaluating
logical conditions. This causes the DTTM field to be accessed even
when PLAV is 0, which results in an ACPI error.
Since this check happens inside various thermal-related ACPI control
methods, various thermal zone become unusable since any attempt to
read their temperature results in an ACPI error.

Fix this by providing support for this operation region. I suspect
that the problem does not happen under Windows (which seemingly does
not use short-circuit evaluation either) because the necessary driver
comes preinstalled with the machine.
Tested-by: Chris <ghostwind@gmail.com>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20240813022903.20567-1-W_Armin@gmx.deReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/lg-laptop.c

@@ -8,6 +8,9 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/acpi.h>
+#include <linux/bits.h>
+#include <linux/device.h>
+#include <linux/dev_printk.h>
 #include <linux/dmi.h>
 #include <linux/input.h>
 #include <linux/input/sparse-keymap.h>
@@ -31,6 +34,26 @@ MODULE_AUTHOR("Matan Ziv-Av");
 MODULE_DESCRIPTION("LG WMI Hotkey Driver");
 MODULE_LICENSE("GPL");
 
+static bool fw_debug;
+module_param(fw_debug, bool, 0);
+MODULE_PARM_DESC(fw_debug, "Enable printing of firmware debug messages");
+
+#define LG_ADDRESS_SPACE_ID			0x8F
+
+#define LG_ADDRESS_SPACE_DEBUG_FLAG_ADR		0x00
+#define LG_ADDRESS_SPACE_FAN_MODE_ADR		0x03
+
+#define LG_ADDRESS_SPACE_DTTM_FLAG_ADR		0x20
+#define LG_ADDRESS_SPACE_CPU_TEMP_ADR		0x21
+#define LG_ADDRESS_SPACE_CPU_TRIP_LOW_ADR	0x22
+#define LG_ADDRESS_SPACE_CPU_TRIP_HIGH_ADR	0x23
+#define LG_ADDRESS_SPACE_MB_TEMP_ADR		0x24
+#define LG_ADDRESS_SPACE_MB_TRIP_LOW_ADR	0x25
+#define LG_ADDRESS_SPACE_MB_TRIP_HIGH_ADR	0x26
+
+#define LG_ADDRESS_SPACE_DEBUG_MSG_START_ADR	0x3E8
+#define LG_ADDRESS_SPACE_DEBUG_MSG_END_ADR	0x5E8
+
 #define WMI_EVENT_GUID0	"E4FB94F9-7F2B-4173-AD1A-CD1D95086248"
 #define WMI_EVENT_GUID1	"023B133E-49D1-4E10-B313-698220140DC2"
 #define WMI_EVENT_GUID2	"37BE1AC0-C3F2-4B1F-BFBE-8FDEAF2814D6"
@@ -646,6 +669,107 @@ static struct platform_driver pf_driver = {
 	}
 };
 
+static acpi_status lg_laptop_address_space_write(struct device *dev, acpi_physical_address address,
+						 size_t size, u64 value)
+{
+	u8 byte;
+
+	/* Ignore any debug messages */
+	if (address >= LG_ADDRESS_SPACE_DEBUG_MSG_START_ADR &&
+	    address <= LG_ADDRESS_SPACE_DEBUG_MSG_END_ADR)
+		return AE_OK;
+
+	if (size != sizeof(byte))
+		return AE_BAD_PARAMETER;
+
+	byte = value & 0xFF;
+
+	switch (address) {
+	case LG_ADDRESS_SPACE_FAN_MODE_ADR:
+		/*
+		 * The fan mode field is not affected by the DTTM flag, so we
+		 * have to manually check fw_debug.
+		 */
+		if (fw_debug)
+			dev_dbg(dev, "Fan mode set to mode %u\n", byte);
+
+		return AE_OK;
+	case LG_ADDRESS_SPACE_CPU_TEMP_ADR:
+		dev_dbg(dev, "CPU temperature is %u °C\n", byte);
+		return AE_OK;
+	case LG_ADDRESS_SPACE_CPU_TRIP_LOW_ADR:
+		dev_dbg(dev, "CPU lower trip point set to %u °C\n", byte);
+		return AE_OK;
+	case LG_ADDRESS_SPACE_CPU_TRIP_HIGH_ADR:
+		dev_dbg(dev, "CPU higher trip point set to %u °C\n", byte);
+		return AE_OK;
+	case LG_ADDRESS_SPACE_MB_TEMP_ADR:
+		dev_dbg(dev, "Motherboard temperature is %u °C\n", byte);
+		return AE_OK;
+	case LG_ADDRESS_SPACE_MB_TRIP_LOW_ADR:
+		dev_dbg(dev, "Motherboard lower trip point set to %u °C\n", byte);
+		return AE_OK;
+	case LG_ADDRESS_SPACE_MB_TRIP_HIGH_ADR:
+		dev_dbg(dev, "Motherboard higher trip point set to %u °C\n", byte);
+		return AE_OK;
+	default:
+		dev_notice_ratelimited(dev, "Ignoring write to unknown opregion address %llu\n",
+				       address);
+		return AE_OK;
+	}
+}
+
+static acpi_status lg_laptop_address_space_read(struct device *dev, acpi_physical_address address,
+						size_t size, u64 *value)
+{
+	if (size != 1)
+		return AE_BAD_PARAMETER;
+
+	switch (address) {
+	case LG_ADDRESS_SPACE_DEBUG_FLAG_ADR:
+		/* Debug messages are already printed using the standard ACPI Debug object */
+		*value = 0x00;
+		return AE_OK;
+	case LG_ADDRESS_SPACE_DTTM_FLAG_ADR:
+		*value = fw_debug;
+		return AE_OK;
+	default:
+		dev_notice_ratelimited(dev, "Attempt to read unknown opregion address %llu\n",
+				       address);
+		return AE_BAD_PARAMETER;
+	}
+}
+
+static acpi_status lg_laptop_address_space_handler(u32 function, acpi_physical_address address,
+						   u32 bits, u64 *value, void *handler_context,
+						   void *region_context)
+{
+	struct device *dev = handler_context;
+	size_t size;
+
+	if (bits % BITS_PER_BYTE)
+		return AE_BAD_PARAMETER;
+
+	size = bits / BITS_PER_BYTE;
+
+	switch (function) {
+	case ACPI_READ:
+		return lg_laptop_address_space_read(dev, address, size, value);
+	case ACPI_WRITE:
+		return lg_laptop_address_space_write(dev, address, size, *value);
+	default:
+		return AE_BAD_PARAMETER;
+	}
+}
+
+static void lg_laptop_remove_address_space_handler(void *data)
+{
+	struct acpi_device *device = data;
+
+	acpi_remove_address_space_handler(device->handle, LG_ADDRESS_SPACE_ID,
+					  &lg_laptop_address_space_handler);
+}
+
 static int acpi_add(struct acpi_device *device)
 {
 	struct platform_device_info pdev_info = {
@@ -653,6 +777,7 @@ static int acpi_add(struct acpi_device *device)
 		.name = PLATFORM_NAME,
 		.id = PLATFORM_DEVID_NONE,
 	};
+	acpi_status status;
 	int ret;
 	const char *product;
 	int year = 2017;
@@ -660,6 +785,17 @@ static int acpi_add(struct acpi_device *device)
 	if (pf_device)
 		return 0;
 
+	status = acpi_install_address_space_handler(device->handle, LG_ADDRESS_SPACE_ID,
+						    &lg_laptop_address_space_handler,
+						    NULL, &device->dev);
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	ret = devm_add_action_or_reset(&device->dev, lg_laptop_remove_address_space_handler,
+				       device);
+	if (ret < 0)
+		return ret;
+
 	ret = platform_driver_register(&pf_driver);
 	if (ret)
 		return ret;