[PATCH v9 4/8] platform/x86: asus-armoury: add apu-mem control support

[Denis Benato <benato.denis96@gmail.com>]

From: "Luke D. Jones" <luke@ljones.dev>

Implement the APU memory size control under the asus-armoury module using
the fw_attributes class.

This allows the APU allocated memory size to be adjusted depending on
the users priority. A reboot is required after change.

Signed-off-by: Luke D. Jones <luke@ljones.dev>
Signed-off-by: Denis Benato <benato.denis96@gmail.com>
---
 drivers/platform/x86/asus-armoury.c        | 81 ++++++++++++++++++++++
 include/linux/platform_data/x86/asus-wmi.h |  2 +
 2 files changed, 83 insertions(+)

diff --git a/drivers/platform/x86/asus-armoury.c b/drivers/platform/x86/asus-armoury.c
index 26513338208c..25b56d4fa53d 100644
--- a/drivers/platform/x86/asus-armoury.c
+++ b/drivers/platform/x86/asus-armoury.c
@@ -396,6 +396,86 @@ static ssize_t egpu_enable_current_value_store(struct kobject *kobj, struct kobj
 WMI_SHOW_INT(egpu_enable_current_value, "%d\n", ASUS_WMI_DEVID_EGPU);
 ATTR_GROUP_BOOL_CUSTOM(egpu_enable, "egpu_enable", "Enable the eGPU (also disables dGPU)");
 
+/* Device memory available to APU */
+
+/* Values map for APU memory: some looks out of order but are actually correct */
+static u32 apu_mem_map[] = {
+	[0] = 0x000, /* called "AUTO" on the BIOS, is the minimum available */
+	[1] = 0x102,
+	[2] = 0x103,
+	[3] = 0x104,
+	[4] = 0x105,
+	[5] = 0x107,
+	[6] = 0x108,
+	[7] = 0x109,
+	[8] = 0x106,
+};
+
+static ssize_t apu_mem_current_value_show(struct kobject *kobj, struct kobj_attribute *attr,
+					  char *buf)
+{
+	int err;
+	u32 mem;
+
+	err = asus_wmi_get_devstate_dsts(ASUS_WMI_DEVID_APU_MEM, &mem);
+	if (err)
+		return err;
+
+	if ((mem & ASUS_WMI_DSTS_PRESENCE_BIT) == 0)
+		return -ENODEV;
+
+	mem &= ~ASUS_WMI_DSTS_PRESENCE_BIT;
+
+	/* After 0x000 is set, a read will return 0x100 */
+	if (mem == 0x100)
+		return sysfs_emit(buf, "0\n");
+
+	for (unsigned int i = 0; i < ARRAY_SIZE(apu_mem_map); i++) {
+		if (apu_mem_map[i] == mem)
+			return sysfs_emit(buf, "%u\n", i);
+	}
+
+	pr_warn("Unrecognised value for APU mem 0x%08x\n", mem);
+	return sysfs_emit(buf, "%u\n", mem);
+}
+
+static ssize_t apu_mem_current_value_store(struct kobject *kobj, struct kobj_attribute *attr,
+					   const char *buf, size_t count)
+{
+	int result, err;
+	u32 requested, mem;
+
+	result = kstrtou32(buf, 10, &requested);
+	if (result)
+		return result;
+
+	if (requested > ARRAY_SIZE(apu_mem_map))
+		return -EINVAL;
+
+	mem = apu_mem_map[requested];
+
+	err = asus_wmi_set_devstate(ASUS_WMI_DEVID_APU_MEM, mem, &result);
+	if (err) {
+		pr_warn("Failed to set apu_mem: %d\n", err);
+		return err;
+	}
+
+	pr_info("APU memory changed to %uGB, reboot required\n", requested+1);
+	sysfs_notify(kobj, NULL, attr->attr.name);
+
+	asus_set_reboot_and_signal_event();
+
+	return count;
+}
+
+static ssize_t apu_mem_possible_values_show(struct kobject *kobj, struct kobj_attribute *attr,
+					    char *buf)
+{
+	BUILD_BUG_ON(ARRAY_SIZE(apu_mem_map) != 9);
+	return sysfs_emit(buf, "0;1;2;3;4;5;6;7;8\n");
+}
+ATTR_GROUP_ENUM_CUSTOM(apu_mem, "apu_mem", "Set available system RAM (in GB) for the APU to use");
+
 /* Simple attribute creation */
 ATTR_GROUP_ENUM_INT_RO(charge_mode, "charge_mode", ASUS_WMI_DEVID_CHARGE_MODE, "0;1;2",
 		       "Show the current mode of charging");
@@ -416,6 +496,7 @@ static const struct asus_attr_group armoury_attr_groups[] = {
 	{ &egpu_connected_attr_group, ASUS_WMI_DEVID_EGPU_CONNECTED },
 	{ &egpu_enable_attr_group, ASUS_WMI_DEVID_EGPU },
 	{ &dgpu_disable_attr_group, ASUS_WMI_DEVID_DGPU },
+	{ &apu_mem_attr_group, ASUS_WMI_DEVID_APU_MEM },
 
 	{ &charge_mode_attr_group, ASUS_WMI_DEVID_CHARGE_MODE },
 	{ &boot_sound_attr_group, ASUS_WMI_DEVID_BOOT_SOUND },
diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
index 52c345de03a8..c0fcdad6443f 100644
--- a/include/linux/platform_data/x86/asus-wmi.h
+++ b/include/linux/platform_data/x86/asus-wmi.h
@@ -137,6 +137,8 @@
 /* dgpu on/off */
 #define ASUS_WMI_DEVID_DGPU		0x00090020
 
+#define ASUS_WMI_DEVID_APU_MEM		0x000600C1
+
 /* gpu mux switch, 0 = dGPU, 1 = Optimus */
 #define ASUS_WMI_DEVID_GPU_MUX		0x00090016
 #define ASUS_WMI_DEVID_GPU_MUX_VIVO	0x00090026
-- 
2.50.0