[PATCH v8 09/15] platform/x86: dell-smbios: Introduce dispatcher for SMM calls

[Mario Limonciello]

This splits up the dell-smbios driver into two drivers:
* dell-smbios
* dell-smbios-smm

dell-smbios can operate with multiple different dispatcher drivers to
perform SMBIOS operations.

Also modify the interface that dell-laptop and dell-wmi use align to this
model more closely.  Rather than a single global buffer being allocated
for all drivers, each driver will allocate and be responsible for it's own
buffer. The pointer will be passed to the calling function and each
dispatcher driver will then internally copy it to the proper location to
perform it's call.

Add defines for calls used by these methods in the dell-smbios.h header
for tracking purposes.

Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxxx>
---
 MAINTAINERS                            |   6 +
 drivers/platform/x86/Kconfig           |  15 +-
 drivers/platform/x86/Makefile          |   1 +
 drivers/platform/x86/dell-laptop.c     | 283 ++++++++++++---------------------
 drivers/platform/x86/dell-smbios-smm.c | 162 +++++++++++++++++++
 drivers/platform/x86/dell-smbios.c     | 120 +++++++-------
 drivers/platform/x86/dell-smbios.h     |  46 +++++-
 drivers/platform/x86/dell-wmi.c        |  11 +-
 8 files changed, 397 insertions(+), 247 deletions(-)
 create mode 100644 drivers/platform/x86/dell-smbios-smm.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 09e774f1d0b2..9dc1ee9603e7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3985,6 +3985,12 @@ L:	platform-driver-x86@xxxxxxxxxxxxxxx
 S:	Maintained
 F:	drivers/platform/x86/dell-smbios.*
 
+DELL SMBIOS SMM DRIVER
+M:	Mario Limonciello <mario.limonciello@xxxxxxxx>
+L:	platform-driver-x86@xxxxxxxxxxxxxxx
+S:	Maintained
+F:	drivers/platform/x86/dell-smbios-smm.c
+
 DELL LAPTOP DRIVER
 M:	Matthew Garrett <mjg59@xxxxxxxxxxxxx>
 M:	Pali RohÃr <pali.rohar@xxxxxxxxx>
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 7722923c968c..53a2de781de6 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -93,12 +93,19 @@ config ASUS_LAPTOP
 
 config DELL_SMBIOS
 	tristate
-	select DCDBAS
+
+config DELL_SMBIOS_SMM
+	tristate "Dell SMBIOS calling interface (SMM implementation)"
+	depends on DCDBAS
+	default DCDBAS
+	select DELL_SMBIOS
 	---help---
-	This module provides common functions for kernel modules using
-	Dell SMBIOS.
+	This provides an implementation for the Dell SMBIOS calling interface
+	communicated over SMI/SMM.
 
-	If you have a Dell laptop, say Y or M here.
+	If you have a Dell computer from <=2017 you should say Y or M here.
+	If you aren't sure and this module doesn't work for your computer
+	it just won't load.
 
 config DELL_LAPTOP
 	tristate "Dell Laptop Extras"
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 8636f5d3424f..e743615241f8 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_MSI_LAPTOP)	+= msi-laptop.o
 obj-$(CONFIG_ACPI_CMPC)		+= classmate-laptop.o
 obj-$(CONFIG_COMPAL_LAPTOP)	+= compal-laptop.o
 obj-$(CONFIG_DELL_SMBIOS)	+= dell-smbios.o
+obj-$(CONFIG_DELL_SMBIOS_SMM)	+= dell-smbios-smm.o
 obj-$(CONFIG_DELL_LAPTOP)	+= dell-laptop.o
 obj-$(CONFIG_DELL_WMI)		+= dell-wmi.o
 obj-$(CONFIG_DELL_WMI_DESCRIPTOR)	+= dell-wmi-descriptor.o
diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index f42159fd2031..39581dd8abbe 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -35,18 +35,6 @@
 #include "dell-rbtn.h"
 #include "dell-smbios.h"
 
-#define BRIGHTNESS_TOKEN 0x7d
-#define KBD_LED_OFF_TOKEN 0x01E1
-#define KBD_LED_ON_TOKEN 0x01E2
-#define KBD_LED_AUTO_TOKEN 0x01E3
-#define KBD_LED_AUTO_25_TOKEN 0x02EA
-#define KBD_LED_AUTO_50_TOKEN 0x02EB
-#define KBD_LED_AUTO_75_TOKEN 0x02EC
-#define KBD_LED_AUTO_100_TOKEN 0x02F6
-#define GLOBAL_MIC_MUTE_ENABLE 0x0364
-#define GLOBAL_MIC_MUTE_DISABLE 0x0365
-#define KBD_LED_AC_TOKEN 0x0451
-
 struct quirk_entry {
 	u8 touchpad_led;
 
@@ -85,6 +73,7 @@ static struct platform_driver platform_driver = {
 	}
 };
 
+static struct calling_interface_buffer *buffer;
 static struct platform_device *platform_device;
 static struct backlight_device *dell_backlight_device;
 static struct rfkill *wifi_rfkill;
@@ -283,6 +272,27 @@ static const struct dmi_system_id dell_quirks[] __initconst = {
 	{ }
 };
 
+void dell_set_arguments(u32 arg0, u32 arg1, u32 arg2, u32 arg3)
+{
+	memset(buffer, 0, sizeof(struct calling_interface_buffer));
+	buffer->input[0] = arg0;
+	buffer->input[1] = arg1;
+	buffer->input[2] = arg2;
+	buffer->input[3] = arg3;
+}
+
+int dell_send_request(u16 class, u16 select)
+{
+	int ret;
+
+	buffer->class = class;
+	buffer->select = select;
+	ret = dell_smbios_call(buffer);
+	if (ret != 0)
+		return ret;
+	return dell_smbios_error(buffer->output[0]);
+}
+
 /*
  * Derived from information in smbios-wireless-ctl:
  *
@@ -405,7 +415,6 @@ static const struct dmi_system_id dell_quirks[] __initconst = {
 
 static int dell_rfkill_set(void *data, bool blocked)
 {
-	struct calling_interface_buffer *buffer;
 	int disable = blocked ? 1 : 0;
 	unsigned long radio = (unsigned long)data;
 	int hwswitch_bit = (unsigned long)data - 1;
@@ -413,20 +422,16 @@ static int dell_rfkill_set(void *data, bool blocked)
 	int status;
 	int ret;
 
-	buffer = dell_smbios_get_buffer();
-
-	dell_smbios_send_request(17, 11);
-	ret = buffer->output[0];
+	dell_set_arguments(0, 0, 0, 0);
+	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
+	if (ret)
+		return ret;
 	status = buffer->output[1];
 
-	if (ret != 0)
-		goto out;
-
-	dell_smbios_clear_buffer();
-
-	buffer->input[0] = 0x2;
-	dell_smbios_send_request(17, 11);
-	ret = buffer->output[0];
+	dell_set_arguments(0x2, 0, 0, 0);
+	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
+	if (ret)
+		return ret;
 	hwswitch = buffer->output[1];
 
 	/* If the hardware switch controls this radio, and the hardware
@@ -435,28 +440,19 @@ static int dell_rfkill_set(void *data, bool blocked)
 	    (status & BIT(0)) && !(status & BIT(16)))
 		disable = 1;
 
-	dell_smbios_clear_buffer();
-
-	buffer->input[0] = (1 | (radio<<8) | (disable << 16));
-	dell_smbios_send_request(17, 11);
-	ret = buffer->output[0];
-
- out:
-	dell_smbios_release_buffer();
-	return dell_smbios_error(ret);
+	dell_set_arguments(1 | (radio<<8) | (disable << 16), 0, 0, 0);
+	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
+	return ret;
 }
 
-/* Must be called with the buffer held */
 static void dell_rfkill_update_sw_state(struct rfkill *rfkill, int radio,
-					int status,
-					struct calling_interface_buffer *buffer)
+					int status)
 {
 	if (status & BIT(0)) {
 		/* Has hw-switch, sync sw_state to BIOS */
 		int block = rfkill_blocked(rfkill);
-		dell_smbios_clear_buffer();
-		buffer->input[0] = (1 | (radio << 8) | (block << 16));
-		dell_smbios_send_request(17, 11);
+		dell_set_arguments(1 | (radio << 8) | (block << 16), 0, 0, 0);
+		dell_send_request(CLASS_INFO, SELECT_RFKILL);
 	} else {
 		/* No hw-switch, sync BIOS state to sw_state */
 		rfkill_set_sw_state(rfkill, !!(status & BIT(radio + 16)));
@@ -472,32 +468,23 @@ static void dell_rfkill_update_hw_state(struct rfkill *rfkill, int radio,
 
 static void dell_rfkill_query(struct rfkill *rfkill, void *data)
 {
-	struct calling_interface_buffer *buffer;
 	int radio = ((unsigned long)data & 0xF);
 	int hwswitch;
 	int status;
 	int ret;
 
-	buffer = dell_smbios_get_buffer();
-
-	dell_smbios_send_request(17, 11);
-	ret = buffer->output[0];
+	dell_set_arguments(0, 0, 0, 0);
+	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
 	status = buffer->output[1];
 
 	if (ret != 0 || !(status & BIT(0))) {
-		dell_smbios_release_buffer();
 		return;
 	}
 
-	dell_smbios_clear_buffer();
-
-	buffer->input[0] = 0x2;
-	dell_smbios_send_request(17, 11);
-	ret = buffer->output[0];
+	dell_set_arguments(0, 0x2, 0, 0);
+	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
 	hwswitch = buffer->output[1];
 
-	dell_smbios_release_buffer();
-
 	if (ret != 0)
 		return;
 
@@ -513,27 +500,23 @@ static struct dentry *dell_laptop_dir;
 
 static int dell_debugfs_show(struct seq_file *s, void *data)
 {
-	struct calling_interface_buffer *buffer;
 	int hwswitch_state;
 	int hwswitch_ret;
 	int status;
 	int ret;
 
-	buffer = dell_smbios_get_buffer();
-
-	dell_smbios_send_request(17, 11);
-	ret = buffer->output[0];
+	dell_set_arguments(0, 0, 0, 0);
+	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
+	if (ret)
+		return ret;
 	status = buffer->output[1];
 
-	dell_smbios_clear_buffer();
-
-	buffer->input[0] = 0x2;
-	dell_smbios_send_request(17, 11);
-	hwswitch_ret = buffer->output[0];
+	dell_set_arguments(0, 0x2, 0, 0);
+	hwswitch_ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
+	if (hwswitch_ret)
+		return hwswitch_ret;
 	hwswitch_state = buffer->output[1];
 
-	dell_smbios_release_buffer();
-
 	seq_printf(s, "return:\t%d\n", ret);
 	seq_printf(s, "status:\t0x%X\n", status);
 	seq_printf(s, "Bit 0 : Hardware switch supported:   %lu\n",
@@ -613,46 +596,36 @@ static const struct file_operations dell_debugfs_fops = {
 
 static void dell_update_rfkill(struct work_struct *ignored)
 {
-	struct calling_interface_buffer *buffer;
 	int hwswitch = 0;
 	int status;
 	int ret;
 
-	buffer = dell_smbios_get_buffer();
-
-	dell_smbios_send_request(17, 11);
-	ret = buffer->output[0];
+	dell_set_arguments(0, 0, 0, 0);
+	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
 	status = buffer->output[1];
 
 	if (ret != 0)
-		goto out;
-
-	dell_smbios_clear_buffer();
+		return;
 
-	buffer->input[0] = 0x2;
-	dell_smbios_send_request(17, 11);
-	ret = buffer->output[0];
+	dell_set_arguments(0, 0x2, 0, 0);
+	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
 
 	if (ret == 0 && (status & BIT(0)))
 		hwswitch = buffer->output[1];
 
 	if (wifi_rfkill) {
 		dell_rfkill_update_hw_state(wifi_rfkill, 1, status, hwswitch);
-		dell_rfkill_update_sw_state(wifi_rfkill, 1, status, buffer);
+		dell_rfkill_update_sw_state(wifi_rfkill, 1, status);
 	}
 	if (bluetooth_rfkill) {
 		dell_rfkill_update_hw_state(bluetooth_rfkill, 2, status,
 					    hwswitch);
-		dell_rfkill_update_sw_state(bluetooth_rfkill, 2, status,
-					    buffer);
+		dell_rfkill_update_sw_state(bluetooth_rfkill, 2, status);
 	}
 	if (wwan_rfkill) {
 		dell_rfkill_update_hw_state(wwan_rfkill, 3, status, hwswitch);
-		dell_rfkill_update_sw_state(wwan_rfkill, 3, status, buffer);
+		dell_rfkill_update_sw_state(wwan_rfkill, 3, status);
 	}
-
- out:
-	dell_smbios_release_buffer();
 }
 static DECLARE_DELAYED_WORK(dell_rfkill_work, dell_update_rfkill);
 
@@ -696,7 +669,6 @@ static struct notifier_block dell_laptop_rbtn_notifier = {
 
 static int __init dell_setup_rfkill(void)
 {
-	struct calling_interface_buffer *buffer;
 	int status, ret, whitelisted;
 	const char *product;
 
@@ -712,11 +684,9 @@ static int __init dell_setup_rfkill(void)
 	if (!force_rfkill && !whitelisted)
 		return 0;
 
-	buffer = dell_smbios_get_buffer();
-	dell_smbios_send_request(17, 11);
-	ret = buffer->output[0];
+	dell_set_arguments(0, 0, 0, 0);
+	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
 	status = buffer->output[1];
-	dell_smbios_release_buffer();
 
 	/* dell wireless info smbios call is not supported */
 	if (ret != 0)
@@ -869,7 +839,6 @@ static void dell_cleanup_rfkill(void)
 
 static int dell_send_intensity(struct backlight_device *bd)
 {
-	struct calling_interface_buffer *buffer;
 	struct calling_interface_token *token;
 	int ret;
 
@@ -877,24 +846,17 @@ static int dell_send_intensity(struct backlight_device *bd)
 	if (!token)
 		return -ENODEV;
 
-	buffer = dell_smbios_get_buffer();
-	buffer->input[0] = token->location;
-	buffer->input[1] = bd->props.brightness;
-
+	dell_set_arguments(token->location, bd->props.brightness, 0, 0);
 	if (power_supply_is_system_supplied() > 0)
-		dell_smbios_send_request(1, 2);
+		ret = dell_send_request(CLASS_TOKEN_WRITE, SELECT_TOKEN_AC);
 	else
-		dell_smbios_send_request(1, 1);
+		ret = dell_send_request(CLASS_TOKEN_WRITE, SELECT_TOKEN_BAT);
 
-	ret = dell_smbios_error(buffer->output[0]);
-
-	dell_smbios_release_buffer();
 	return ret;
 }
 
 static int dell_get_intensity(struct backlight_device *bd)
 {
-	struct calling_interface_buffer *buffer;
 	struct calling_interface_token *token;
 	int ret;
 
@@ -902,20 +864,14 @@ static int dell_get_intensity(struct backlight_device *bd)
 	if (!token)
 		return -ENODEV;
 
-	buffer = dell_smbios_get_buffer();
-	buffer->input[0] = token->location;
-
+	dell_set_arguments(token->location, 0, 0, 0);
 	if (power_supply_is_system_supplied() > 0)
-		dell_smbios_send_request(0, 2);
+		ret = dell_send_request(CLASS_TOKEN_READ, SELECT_TOKEN_AC);
 	else
-		dell_smbios_send_request(0, 1);
+		ret = dell_send_request(CLASS_TOKEN_READ, SELECT_TOKEN_BAT);
 
-	if (buffer->output[0])
-		ret = dell_smbios_error(buffer->output[0]);
-	else
+	if (ret == 0)
 		ret = buffer->output[1];
-
-	dell_smbios_release_buffer();
 	return ret;
 }
 
@@ -1179,20 +1135,13 @@ static DEFINE_MUTEX(kbd_led_mutex);
 
 static int kbd_get_info(struct kbd_info *info)
 {
-	struct calling_interface_buffer *buffer;
 	u8 units;
 	int ret;
 
-	buffer = dell_smbios_get_buffer();
-
-	buffer->input[0] = 0x0;
-	dell_smbios_send_request(4, 11);
-	ret = buffer->output[0];
-
-	if (ret) {
-		ret = dell_smbios_error(ret);
-		goto out;
-	}
+	dell_set_arguments(0, 0, 0, 0);
+	ret = dell_send_request(CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT);
+	if (ret)
+		return ret;
 
 	info->modes = buffer->output[1] & 0xFFFF;
 	info->type = (buffer->output[1] >> 24) & 0xFF;
@@ -1209,8 +1158,6 @@ static int kbd_get_info(struct kbd_info *info)
 	if (units & BIT(3))
 		info->days = (buffer->output[3] >> 24) & 0xFF;
 
- out:
-	dell_smbios_release_buffer();
 	return ret;
 }
 
@@ -1269,19 +1216,12 @@ static int kbd_set_level(struct kbd_state *state, u8 level)
 
 static int kbd_get_state(struct kbd_state *state)
 {
-	struct calling_interface_buffer *buffer;
 	int ret;
 
-	buffer = dell_smbios_get_buffer();
-
-	buffer->input[0] = 0x1;
-	dell_smbios_send_request(4, 11);
-	ret = buffer->output[0];
-
-	if (ret) {
-		ret = dell_smbios_error(ret);
-		goto out;
-	}
+	dell_set_arguments(0x1, 0, 0, 0);
+	ret = dell_send_request(CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT);
+	if (ret)
+		return ret;
 
 	state->mode_bit = ffs(buffer->output[1] & 0xFFFF);
 	if (state->mode_bit != 0)
@@ -1296,31 +1236,27 @@ static int kbd_get_state(struct kbd_state *state)
 	state->timeout_value_ac = (buffer->output[2] >> 24) & 0x3F;
 	state->timeout_unit_ac = (buffer->output[2] >> 30) & 0x3;
 
- out:
-	dell_smbios_release_buffer();
 	return ret;
 }
 
 static int kbd_set_state(struct kbd_state *state)
 {
-	struct calling_interface_buffer *buffer;
 	int ret;
+	u32 input1;
+	u32 input2;
+
+	input1 = BIT(state->mode_bit) & 0xFFFF;
+	input1 |= (state->triggers & 0xFF) << 16;
+	input1 |= (state->timeout_value & 0x3F) << 24;
+	input1 |= (state->timeout_unit & 0x3) << 30;
+	input2 = state->als_setting & 0xFF;
+	input2 |= (state->level & 0xFF) << 16;
+	input2 |= (state->timeout_value_ac & 0x3F) << 24;
+	input2 |= (state->timeout_unit_ac & 0x3) << 30;
+	dell_set_arguments(0x2, input1, input2, 0);
+	ret = dell_send_request(CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT);
 
-	buffer = dell_smbios_get_buffer();
-	buffer->input[0] = 0x2;
-	buffer->input[1] = BIT(state->mode_bit) & 0xFFFF;
-	buffer->input[1] |= (state->triggers & 0xFF) << 16;
-	buffer->input[1] |= (state->timeout_value & 0x3F) << 24;
-	buffer->input[1] |= (state->timeout_unit & 0x3) << 30;
-	buffer->input[2] = state->als_setting & 0xFF;
-	buffer->input[2] |= (state->level & 0xFF) << 16;
-	buffer->input[2] |= (state->timeout_value_ac & 0x3F) << 24;
-	buffer->input[2] |= (state->timeout_unit_ac & 0x3) << 30;
-	dell_smbios_send_request(4, 11);
-	ret = buffer->output[0];
-	dell_smbios_release_buffer();
-
-	return dell_smbios_error(ret);
+	return ret;
 }
 
 static int kbd_set_state_safe(struct kbd_state *state, struct kbd_state *old)
@@ -1345,7 +1281,6 @@ static int kbd_set_state_safe(struct kbd_state *state, struct kbd_state *old)
 
 static int kbd_set_token_bit(u8 bit)
 {
-	struct calling_interface_buffer *buffer;
 	struct calling_interface_token *token;
 	int ret;
 
@@ -1356,19 +1291,14 @@ static int kbd_set_token_bit(u8 bit)
 	if (!token)
 		return -EINVAL;
 
-	buffer = dell_smbios_get_buffer();
-	buffer->input[0] = token->location;
-	buffer->input[1] = token->value;
-	dell_smbios_send_request(1, 0);
-	ret = buffer->output[0];
-	dell_smbios_release_buffer();
+	dell_set_arguments(token->location, token->value, 0, 0);
+	ret = dell_send_request(CLASS_TOKEN_WRITE, SELECT_TOKEN_STD);
 
-	return dell_smbios_error(ret);
+	return ret;
 }
 
 static int kbd_get_token_bit(u8 bit)
 {
-	struct calling_interface_buffer *buffer;
 	struct calling_interface_token *token;
 	int ret;
 	int val;
@@ -1380,15 +1310,12 @@ static int kbd_get_token_bit(u8 bit)
 	if (!token)
 		return -EINVAL;
 
-	buffer = dell_smbios_get_buffer();
-	buffer->input[0] = token->location;
-	dell_smbios_send_request(0, 0);
-	ret = buffer->output[0];
+	dell_set_arguments(token->location, 0, 0, 0);
+	ret = dell_send_request(CLASS_TOKEN_READ, SELECT_TOKEN_STD);
 	val = buffer->output[1];
-	dell_smbios_release_buffer();
 
 	if (ret)
-		return dell_smbios_error(ret);
+		return ret;
 
 	return (val == token->value);
 }
@@ -2102,7 +2029,6 @@ static struct notifier_block dell_laptop_notifier = {
 
 int dell_micmute_led_set(int state)
 {
-	struct calling_interface_buffer *buffer;
 	struct calling_interface_token *token;
 
 	if (state == 0)
@@ -2115,11 +2041,8 @@ int dell_micmute_led_set(int state)
 	if (!token)
 		return -ENODEV;
 
-	buffer = dell_smbios_get_buffer();
-	buffer->input[0] = token->location;
-	buffer->input[1] = token->value;
-	dell_smbios_send_request(1, 0);
-	dell_smbios_release_buffer();
+	dell_set_arguments(token->location, token->value, 0, 0);
+	dell_send_request(CLASS_TOKEN_WRITE, SELECT_TOKEN_STD);
 
 	return state;
 }
@@ -2127,7 +2050,6 @@ EXPORT_SYMBOL_GPL(dell_micmute_led_set);
 
 static int __init dell_init(void)
 {
-	struct calling_interface_buffer *buffer;
 	struct calling_interface_token *token;
 	int max_intensity = 0;
 	int ret;
@@ -2158,6 +2080,10 @@ static int __init dell_init(void)
 		goto fail_rfkill;
 	}
 
+	buffer = kzalloc(sizeof(struct calling_interface_buffer), GFP_KERNEL);
+	if (!buffer)
+		goto fail_buffer;
+
 	if (quirks && quirks->touchpad_led)
 		touchpad_led_init(&platform_device->dev);
 
@@ -2175,12 +2101,10 @@ static int __init dell_init(void)
 
 	token = dell_smbios_find_token(BRIGHTNESS_TOKEN);
 	if (token) {
-		buffer = dell_smbios_get_buffer();
-		buffer->input[0] = token->location;
-		dell_smbios_send_request(0, 2);
-		if (buffer->output[0] == 0)
+		dell_set_arguments(token->location, 0, 0, 0);
+		ret = dell_send_request(CLASS_TOKEN_READ, SELECT_TOKEN_AC);
+		if (ret)
 			max_intensity = buffer->output[3];
-		dell_smbios_release_buffer();
 	}
 
 	if (max_intensity) {
@@ -2214,6 +2138,8 @@ static int __init dell_init(void)
 fail_get_brightness:
 	backlight_device_unregister(dell_backlight_device);
 fail_backlight:
+	kfree(buffer);
+fail_buffer:
 	dell_cleanup_rfkill();
 fail_rfkill:
 	platform_device_del(platform_device);
@@ -2233,6 +2159,7 @@ static void __exit dell_exit(void)
 		touchpad_led_exit();
 	kbd_led_exit();
 	backlight_device_unregister(dell_backlight_device);
+	kfree(buffer);
 	dell_cleanup_rfkill();
 	if (platform_device) {
 		platform_device_unregister(platform_device);
diff --git a/drivers/platform/x86/dell-smbios-smm.c b/drivers/platform/x86/dell-smbios-smm.c
new file mode 100644
index 000000000000..bd5a63a4aa15
--- /dev/null
+++ b/drivers/platform/x86/dell-smbios-smm.c
@@ -0,0 +1,162 @@
+/*
+ *  SMI methods for use with dell-smbios
+ *
+ *  Copyright (c) Red Hat <mjg@xxxxxxxxxx>
+ *  Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@xxxxxxxxx>
+ *  Copyright (c) 2014 Pali RohÃr <pali.rohar@xxxxxxxxx>
+ *  Copyright (c) 2017 Dell Inc.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/dmi.h>
+#include <linux/gfp.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include "../../firmware/dcdbas.h"
+#include "dell-smbios.h"
+
+static int da_command_address;
+static int da_command_code;
+static struct calling_interface_buffer *buffer;
+struct platform_device *platform_device;
+static DEFINE_MUTEX(smm_mutex);
+
+static const struct dmi_system_id dell_device_table[] __initconst = {
+	{
+		.ident = "Dell laptop",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_CHASSIS_TYPE, "8"),
+		},
+	},
+	{
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_CHASSIS_TYPE, "9"), /*Laptop*/
+		},
+	},
+	{
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_CHASSIS_TYPE, "10"), /*Notebook*/
+		},
+	},
+	{
+		.ident = "Dell Computer Corporation",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
+			DMI_MATCH(DMI_CHASSIS_TYPE, "8"),
+		},
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(dmi, dell_device_table);
+
+static void __init parse_da_table(const struct dmi_header *dm)
+{
+	struct calling_interface_structure *table =
+		container_of(dm, struct calling_interface_structure, header);
+
+	/* 4 bytes of table header, plus 7 bytes of Dell header, plus at least
+	 * 6 bytes of entry
+	 */
+	if (dm->length < 17)
+		return;
+
+	da_command_address = table->cmdIOAddress;
+	da_command_code = table->cmdIOCode;
+}
+
+static void __init find_cmd_address(const struct dmi_header *dm, void *dummy)
+{
+	switch (dm->type) {
+	case 0xda: /* Calling interface */
+		parse_da_table(dm);
+		break;
+	}
+}
+
+int dell_smbios_smm_call(struct calling_interface_buffer *input)
+{
+	struct smi_cmd command;
+	size_t size;
+
+	size = sizeof(struct calling_interface_buffer);
+	command.magic = SMI_CMD_MAGIC;
+	command.command_address = da_command_address;
+	command.command_code = da_command_code;
+	command.ebx = virt_to_phys(buffer);
+	command.ecx = 0x42534931;
+
+	mutex_lock(&smm_mutex);
+	memcpy(buffer, input, size);
+	dcdbas_smi_request(&command);
+	memcpy(input, buffer, size);
+	mutex_unlock(&smm_mutex);
+	return 0;
+}
+
+static int __init dell_smbios_smm_init(void)
+{
+	int ret;
+	/*
+	 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
+	 * is passed to SMI handler.
+	 */
+	buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
+	if (!buffer)
+		return -ENOMEM;
+
+	dmi_walk(find_cmd_address, NULL);
+
+	platform_device = platform_device_alloc("dell-smbios", 1);
+	if (!platform_device) {
+		ret = -ENOMEM;
+		goto fail_platform_device_alloc;
+	}
+
+	ret = platform_device_add(platform_device);
+	if (ret)
+		goto fail_platform_device_add;
+
+	ret = dell_smbios_register_device(&platform_device->dev,
+					  &dell_smbios_smm_call);
+	if (ret)
+		goto fail_register;
+
+	return 0;
+
+fail_register:
+	platform_device_del(platform_device);
+
+fail_platform_device_add:
+	platform_device_put(platform_device);
+
+fail_platform_device_alloc:
+	free_page((unsigned long)buffer);
+	return ret;
+}
+
+static void __exit dell_smbios_smm_exit(void)
+{
+	if (platform_device) {
+		dell_smbios_unregister_device(&platform_device->dev);
+		platform_device_unregister(platform_device);
+		free_page((unsigned long)buffer);
+	}
+}
+
+subsys_initcall(dell_smbios_smm_init);
+module_exit(dell_smbios_smm_exit);
+
+MODULE_AUTHOR("Matthew Garrett <mjg@xxxxxxxxxx>");
+MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@xxxxxxxxx>");
+MODULE_AUTHOR("Pali RohÃr <pali.rohar@xxxxxxxxx>");
+MODULE_AUTHOR("Mario Limonciello <mario.limonciello@xxxxxxxx>");
+MODULE_DESCRIPTION("Dell SMBIOS communications over SMI");
+MODULE_LICENSE("GPL");
diff --git a/drivers/platform/x86/dell-smbios.c b/drivers/platform/x86/dell-smbios.c
index eb973ba4f912..b1939abc4216 100644
--- a/drivers/platform/x86/dell-smbios.c
+++ b/drivers/platform/x86/dell-smbios.c
@@ -18,33 +18,27 @@
 #include <linux/module.h>
 #include <linux/dmi.h>
 #include <linux/err.h>
-#include <linux/gfp.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/io.h>
-#include "../../firmware/dcdbas.h"
 #include <linux/platform_device.h>
 #include "dell-smbios.h"
 
-struct calling_interface_structure {
-	struct dmi_header header;
-	u16 cmdIOAddress;
-	u8 cmdIOCode;
-	u32 supportedCmds;
-	struct calling_interface_token tokens[];
-} __packed;
-
-static struct calling_interface_buffer *buffer;
-static DEFINE_MUTEX(buffer_mutex);
-
-static int da_command_address;
-static int da_command_code;
 static int da_num_tokens;
 static struct platform_device *platform_device;
 static struct calling_interface_token *da_tokens;
 static struct device_attribute *token_location_attrs;
 static struct device_attribute *token_value_attrs;
 static struct attribute **token_attrs;
+static DEFINE_MUTEX(smbios_mutex);
+
+struct smbios_device {
+	struct list_head list;
+	struct device *device;
+	int (*call_fn)(struct calling_interface_buffer *);
+};
+
+static LIST_HEAD(smbios_device_list);
 
 int dell_smbios_error(int value)
 {
@@ -61,42 +55,71 @@ int dell_smbios_error(int value)
 }
 EXPORT_SYMBOL_GPL(dell_smbios_error);
 
-struct calling_interface_buffer *dell_smbios_get_buffer(void)
+int dell_smbios_register_device(struct device *d, void *call_fn)
 {
-	mutex_lock(&buffer_mutex);
-	dell_smbios_clear_buffer();
-	return buffer;
-}
-EXPORT_SYMBOL_GPL(dell_smbios_get_buffer);
+	struct smbios_device *priv;
 
-void dell_smbios_clear_buffer(void)
-{
-	memset(buffer, 0, sizeof(struct calling_interface_buffer));
+	priv = devm_kzalloc(d, sizeof(struct smbios_device), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+	get_device(d);
+	priv->device = d;
+	priv->call_fn = call_fn;
+	mutex_lock(&smbios_mutex);
+	list_add_tail(&priv->list, &smbios_device_list);
+	mutex_unlock(&smbios_mutex);
+	dev_dbg(d, "Added device: %s\n", d->driver->name);
+	return 0;
 }
-EXPORT_SYMBOL_GPL(dell_smbios_clear_buffer);
+EXPORT_SYMBOL_GPL(dell_smbios_register_device);
 
-void dell_smbios_release_buffer(void)
+void dell_smbios_unregister_device(struct device *d)
 {
-	mutex_unlock(&buffer_mutex);
+	struct smbios_device *priv;
+
+	mutex_lock(&smbios_mutex);
+	list_for_each_entry(priv, &smbios_device_list, list) {
+		if (priv->device == d) {
+			list_del(&priv->list);
+			put_device(d);
+			break;
+		}
+	};
+	mutex_unlock(&smbios_mutex);
+	dev_dbg(d, "Remove device: %s\n", d->driver->name);
 }
-EXPORT_SYMBOL_GPL(dell_smbios_release_buffer);
+EXPORT_SYMBOL_GPL(dell_smbios_unregister_device);
 
-void dell_smbios_send_request(int class, int select)
+int dell_smbios_call(struct calling_interface_buffer *buffer)
 {
-	struct smi_cmd command;
+	int (*call_fn)(struct calling_interface_buffer *) = NULL;
+	struct device *selected_dev = NULL;
+	struct smbios_device *priv;
+	int ret;
 
-	command.magic = SMI_CMD_MAGIC;
-	command.command_address = da_command_address;
-	command.command_code = da_command_code;
-	command.ebx = virt_to_phys(buffer);
-	command.ecx = 0x42534931;
+	mutex_lock(&smbios_mutex);
+	list_for_each_entry(priv, &smbios_device_list, list) {
+		if (!selected_dev || priv->device->id >= selected_dev->id) {
+			dev_dbg(priv->device, "Trying device ID: %d\n",
+				priv->device->id);
+			call_fn = priv->call_fn;
+			selected_dev = priv->device;
+		}
+	};
 
-	buffer->class = class;
-	buffer->select = select;
+	if (!selected_dev) {
+		ret = -ENODEV;
+		pr_err("No dell-smbios drivers are loaded\n");
+		goto out_smbios_call;
+	}
 
-	dcdbas_smi_request(&command);
+	ret = call_fn(buffer);
+
+out_smbios_call:
+	mutex_unlock(&smbios_mutex);
+	return ret;
 }
-EXPORT_SYMBOL_GPL(dell_smbios_send_request);
+EXPORT_SYMBOL_GPL(dell_smbios_call);
 
 struct calling_interface_token *dell_smbios_find_token(int tokenid)
 {
@@ -145,9 +168,6 @@ static void __init parse_da_table(const struct dmi_header *dm)
 	if (dm->length < 17)
 		return;
 
-	da_command_address = table->cmdIOAddress;
-	da_command_code = table->cmdIOCode;
-
 	new_da_tokens = krealloc(da_tokens, (da_num_tokens + tokens) *
 				 sizeof(struct calling_interface_token),
 				 GFP_KERNEL);
@@ -342,7 +362,6 @@ static void free_group(struct platform_device *pdev)
 	kfree(token_location_attrs);
 }
 
-
 static int __init dell_smbios_init(void)
 {
 	const struct dmi_device *valid;
@@ -361,15 +380,6 @@ static int __init dell_smbios_init(void)
 		return -ENODEV;
 	}
 
-	/*
-	 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
-	 * is passed to SMI handler.
-	 */
-	buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
-	if (!buffer) {
-		ret = -ENOMEM;
-		goto fail_buffer;
-	}
 	ret = platform_driver_register(&platform_driver);
 	if (ret)
 		goto fail_platform_driver;
@@ -402,22 +412,20 @@ static int __init dell_smbios_init(void)
 	platform_driver_unregister(&platform_driver);
 
 fail_platform_driver:
-	free_page((unsigned long)buffer);
-
-fail_buffer:
 	kfree(da_tokens);
 	return ret;
 }
 
 static void __exit dell_smbios_exit(void)
 {
+	mutex_lock(&smbios_mutex);
 	if (platform_device) {
 		free_group(platform_device);
 		platform_device_unregister(platform_device);
 		platform_driver_unregister(&platform_driver);
 	}
-	free_page((unsigned long)buffer);
 	kfree(da_tokens);
+	mutex_unlock(&smbios_mutex);
 }
 
 subsys_initcall(dell_smbios_init);
diff --git a/drivers/platform/x86/dell-smbios.h b/drivers/platform/x86/dell-smbios.h
index 45cbc2292cd3..8df330abeb5d 100644
--- a/drivers/platform/x86/dell-smbios.h
+++ b/drivers/platform/x86/dell-smbios.h
@@ -16,6 +16,35 @@
 #ifndef _DELL_SMBIOS_H_
 #define _DELL_SMBIOS_H_
 
+#include <linux/device.h>
+
+/* Common classes and selects*/
+#define CLASS_TOKEN_READ 0
+#define CLASS_TOKEN_WRITE 1
+#define SELECT_TOKEN_STD 0
+#define SELECT_TOKEN_BAT 1
+#define SELECT_TOKEN_AC 2
+#define CLASS_KBD_BACKLIGHT 4
+#define SELECT_KBD_BACKLIGHT 11
+#define CLASS_INFO 17
+#define SELECT_RFKILL 11
+#define SELECT_APP_REGISTRATION	3
+
+/* Tokens used in kernel drivers, any of these
+ * should be filtered from userspace access
+ */
+#define BRIGHTNESS_TOKEN	0x007d
+#define KBD_LED_AC_TOKEN	0x0451
+#define KBD_LED_OFF_TOKEN	0x01E1
+#define KBD_LED_ON_TOKEN	0x01E2
+#define KBD_LED_AUTO_TOKEN	0x01E3
+#define KBD_LED_AUTO_25_TOKEN	0x02EA
+#define KBD_LED_AUTO_50_TOKEN	0x02EB
+#define KBD_LED_AUTO_75_TOKEN	0x02EC
+#define KBD_LED_AUTO_100_TOKEN	0x02F6
+#define GLOBAL_MIC_MUTE_ENABLE	0x0364
+#define GLOBAL_MIC_MUTE_DISABLE	0x0365
+
 struct notifier_block;
 
 /* This structure will be modified by the firmware when we enter
@@ -37,12 +66,19 @@ struct calling_interface_token {
 	};
 };
 
-int dell_smbios_error(int value);
+struct calling_interface_structure {
+	struct dmi_header header;
+	u16 cmdIOAddress;
+	u8 cmdIOCode;
+	u32 supportedCmds;
+	struct calling_interface_token tokens[];
+} __packed;
 
-struct calling_interface_buffer *dell_smbios_get_buffer(void);
-void dell_smbios_clear_buffer(void);
-void dell_smbios_release_buffer(void);
-void dell_smbios_send_request(int class, int select);
+int dell_smbios_register_device(struct device *d, void *call_fn);
+void dell_smbios_unregister_device(struct device *d);
+
+int dell_smbios_error(int value);
+int dell_smbios_call(struct calling_interface_buffer *buffer);
 
 struct calling_interface_token *dell_smbios_find_token(int tokenid);
 
diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c
index b74d328c9da2..d2dfdbcadf46 100644
--- a/drivers/platform/x86/dell-wmi.c
+++ b/drivers/platform/x86/dell-wmi.c
@@ -638,13 +638,16 @@ static int dell_wmi_events_set_enabled(bool enable)
 	struct calling_interface_buffer *buffer;
 	int ret;
 
-	buffer = dell_smbios_get_buffer();
+	buffer = kzalloc(sizeof(struct calling_interface_buffer), GFP_KERNEL);
+	buffer->class = CLASS_INFO;
+	buffer->select = SELECT_APP_REGISTRATION;
 	buffer->input[0] = 0x10000;
 	buffer->input[1] = 0x51534554;
 	buffer->input[3] = enable;
-	dell_smbios_send_request(17, 3);
-	ret = buffer->output[0];
-	dell_smbios_release_buffer();
+	ret = dell_smbios_call(buffer);
+	if (ret == 0)
+		ret = buffer->output[0];
+	kfree(buffer);
 
 	return dell_smbios_error(ret);
 }
-- 
2.14.1