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path: root/drivers/platform/x86/dell-laptop.c
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Diffstat (limited to 'drivers/platform/x86/dell-laptop.c')
-rw-r--r--drivers/platform/x86/dell-laptop.c448
1 files changed, 349 insertions, 99 deletions
diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index 2c1d5f543..aaeeae81e 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -31,7 +31,9 @@
#include <linux/slab.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
+#include <acpi/video.h>
#include "../../firmware/dcdbas.h"
+#include "dell-rbtn.h"
#define BRIGHTNESS_TOKEN 0x7d
#define KBD_LED_OFF_TOKEN 0x01E1
@@ -307,12 +309,15 @@ static const struct dmi_system_id dell_quirks[] __initconst = {
static struct calling_interface_buffer *buffer;
static DEFINE_MUTEX(buffer_mutex);
-static int hwswitch_state;
+static void clear_buffer(void)
+{
+ memset(buffer, 0, sizeof(struct calling_interface_buffer));
+}
static void get_buffer(void)
{
mutex_lock(&buffer_mutex);
- memset(buffer, 0, sizeof(struct calling_interface_buffer));
+ clear_buffer();
}
static void release_buffer(void)
@@ -421,66 +426,166 @@ static inline int dell_smi_error(int value)
}
}
-/* Derived from information in DellWirelessCtl.cpp:
- Class 17, select 11 is radio control. It returns an array of 32-bit values.
-
- Input byte 0 = 0: Wireless information
-
- result[0]: return code
- result[1]:
- Bit 0: Hardware switch supported
- Bit 1: Wifi locator supported
- Bit 2: Wifi is supported
- Bit 3: Bluetooth is supported
- Bit 4: WWAN is supported
- Bit 5: Wireless keyboard supported
- Bits 6-7: Reserved
- Bit 8: Wifi is installed
- Bit 9: Bluetooth is installed
- Bit 10: WWAN is installed
- Bits 11-15: Reserved
- Bit 16: Hardware switch is on
- Bit 17: Wifi is blocked
- Bit 18: Bluetooth is blocked
- Bit 19: WWAN is blocked
- Bits 20-31: Reserved
- result[2]: NVRAM size in bytes
- result[3]: NVRAM format version number
-
- Input byte 0 = 2: Wireless switch configuration
- result[0]: return code
- result[1]:
- Bit 0: Wifi controlled by switch
- Bit 1: Bluetooth controlled by switch
- Bit 2: WWAN controlled by switch
- Bits 3-6: Reserved
- Bit 7: Wireless switch config locked
- Bit 8: Wifi locator enabled
- Bits 9-14: Reserved
- Bit 15: Wifi locator setting locked
- Bits 16-31: Reserved
-*/
+/*
+ * Derived from information in smbios-wireless-ctl:
+ *
+ * cbSelect 17, Value 11
+ *
+ * Return Wireless Info
+ * cbArg1, byte0 = 0x00
+ *
+ * cbRes1 Standard return codes (0, -1, -2)
+ * cbRes2 Info bit flags:
+ *
+ * 0 Hardware switch supported (1)
+ * 1 WiFi locator supported (1)
+ * 2 WLAN supported (1)
+ * 3 Bluetooth (BT) supported (1)
+ * 4 WWAN supported (1)
+ * 5 Wireless KBD supported (1)
+ * 6 Uw b supported (1)
+ * 7 WiGig supported (1)
+ * 8 WLAN installed (1)
+ * 9 BT installed (1)
+ * 10 WWAN installed (1)
+ * 11 Uw b installed (1)
+ * 12 WiGig installed (1)
+ * 13-15 Reserved (0)
+ * 16 Hardware (HW) switch is On (1)
+ * 17 WLAN disabled (1)
+ * 18 BT disabled (1)
+ * 19 WWAN disabled (1)
+ * 20 Uw b disabled (1)
+ * 21 WiGig disabled (1)
+ * 20-31 Reserved (0)
+ *
+ * cbRes3 NVRAM size in bytes
+ * cbRes4, byte 0 NVRAM format version number
+ *
+ *
+ * Set QuickSet Radio Disable Flag
+ * cbArg1, byte0 = 0x01
+ * cbArg1, byte1
+ * Radio ID value:
+ * 0 Radio Status
+ * 1 WLAN ID
+ * 2 BT ID
+ * 3 WWAN ID
+ * 4 UWB ID
+ * 5 WIGIG ID
+ * cbArg1, byte2 Flag bits:
+ * 0 QuickSet disables radio (1)
+ * 1-7 Reserved (0)
+ *
+ * cbRes1 Standard return codes (0, -1, -2)
+ * cbRes2 QuickSet (QS) radio disable bit map:
+ * 0 QS disables WLAN
+ * 1 QS disables BT
+ * 2 QS disables WWAN
+ * 3 QS disables UWB
+ * 4 QS disables WIGIG
+ * 5-31 Reserved (0)
+ *
+ * Wireless Switch Configuration
+ * cbArg1, byte0 = 0x02
+ *
+ * cbArg1, byte1
+ * Subcommand:
+ * 0 Get config
+ * 1 Set config
+ * 2 Set WiFi locator enable/disable
+ * cbArg1,byte2
+ * Switch settings (if byte 1==1):
+ * 0 WLAN sw itch control (1)
+ * 1 BT sw itch control (1)
+ * 2 WWAN sw itch control (1)
+ * 3 UWB sw itch control (1)
+ * 4 WiGig sw itch control (1)
+ * 5-7 Reserved (0)
+ * cbArg1, byte2 Enable bits (if byte 1==2):
+ * 0 Enable WiFi locator (1)
+ *
+ * cbRes1 Standard return codes (0, -1, -2)
+ * cbRes2 QuickSet radio disable bit map:
+ * 0 WLAN controlled by sw itch (1)
+ * 1 BT controlled by sw itch (1)
+ * 2 WWAN controlled by sw itch (1)
+ * 3 UWB controlled by sw itch (1)
+ * 4 WiGig controlled by sw itch (1)
+ * 5-6 Reserved (0)
+ * 7 Wireless sw itch config locked (1)
+ * 8 WiFi locator enabled (1)
+ * 9-14 Reserved (0)
+ * 15 WiFi locator setting locked (1)
+ * 16-31 Reserved (0)
+ *
+ * Read Local Config Data (LCD)
+ * cbArg1, byte0 = 0x10
+ * cbArg1, byte1 NVRAM index low byte
+ * cbArg1, byte2 NVRAM index high byte
+ * cbRes1 Standard return codes (0, -1, -2)
+ * cbRes2 4 bytes read from LCD[index]
+ * cbRes3 4 bytes read from LCD[index+4]
+ * cbRes4 4 bytes read from LCD[index+8]
+ *
+ * Write Local Config Data (LCD)
+ * cbArg1, byte0 = 0x11
+ * cbArg1, byte1 NVRAM index low byte
+ * cbArg1, byte2 NVRAM index high byte
+ * cbArg2 4 bytes to w rite at LCD[index]
+ * cbArg3 4 bytes to w rite at LCD[index+4]
+ * cbArg4 4 bytes to w rite at LCD[index+8]
+ * cbRes1 Standard return codes (0, -1, -2)
+ *
+ * Populate Local Config Data from NVRAM
+ * cbArg1, byte0 = 0x12
+ * cbRes1 Standard return codes (0, -1, -2)
+ *
+ * Commit Local Config Data to NVRAM
+ * cbArg1, byte0 = 0x13
+ * cbRes1 Standard return codes (0, -1, -2)
+ */
static int dell_rfkill_set(void *data, bool blocked)
{
int disable = blocked ? 1 : 0;
unsigned long radio = (unsigned long)data;
int hwswitch_bit = (unsigned long)data - 1;
+ int hwswitch;
+ int status;
+ int ret;
get_buffer();
+
+ dell_send_request(buffer, 17, 11);
+ ret = buffer->output[0];
+ status = buffer->output[1];
+
+ if (ret != 0)
+ goto out;
+
+ clear_buffer();
+
+ buffer->input[0] = 0x2;
dell_send_request(buffer, 17, 11);
+ ret = buffer->output[0];
+ hwswitch = buffer->output[1];
/* If the hardware switch controls this radio, and the hardware
switch is disabled, always disable the radio */
- if ((hwswitch_state & BIT(hwswitch_bit)) &&
- !(buffer->output[1] & BIT(16)))
+ if (ret == 0 && (hwswitch & BIT(hwswitch_bit)) &&
+ (status & BIT(0)) && !(status & BIT(16)))
disable = 1;
+ clear_buffer();
+
buffer->input[0] = (1 | (radio<<8) | (disable << 16));
dell_send_request(buffer, 17, 11);
+ ret = buffer->output[0];
+ out:
release_buffer();
- return 0;
+ return dell_smi_error(ret);
}
/* Must be called with the buffer held */
@@ -490,6 +595,7 @@ static void dell_rfkill_update_sw_state(struct rfkill *rfkill, int radio,
if (status & BIT(0)) {
/* Has hw-switch, sync sw_state to BIOS */
int block = rfkill_blocked(rfkill);
+ clear_buffer();
buffer->input[0] = (1 | (radio << 8) | (block << 16));
dell_send_request(buffer, 17, 11);
} else {
@@ -499,23 +605,43 @@ static void dell_rfkill_update_sw_state(struct rfkill *rfkill, int radio,
}
static void dell_rfkill_update_hw_state(struct rfkill *rfkill, int radio,
- int status)
+ int status, int hwswitch)
{
- if (hwswitch_state & (BIT(radio - 1)))
+ if (hwswitch & (BIT(radio - 1)))
rfkill_set_hw_state(rfkill, !(status & BIT(16)));
}
static void dell_rfkill_query(struct rfkill *rfkill, void *data)
{
+ int radio = ((unsigned long)data & 0xF);
+ int hwswitch;
int status;
+ int ret;
get_buffer();
+
dell_send_request(buffer, 17, 11);
+ ret = buffer->output[0];
status = buffer->output[1];
- dell_rfkill_update_hw_state(rfkill, (unsigned long)data, status);
+ if (ret != 0 || !(status & BIT(0))) {
+ release_buffer();
+ return;
+ }
+
+ clear_buffer();
+
+ buffer->input[0] = 0x2;
+ dell_send_request(buffer, 17, 11);
+ ret = buffer->output[0];
+ hwswitch = buffer->output[1];
release_buffer();
+
+ if (ret != 0)
+ return;
+
+ dell_rfkill_update_hw_state(rfkill, radio, status, hwswitch);
}
static const struct rfkill_ops dell_rfkill_ops = {
@@ -527,13 +653,27 @@ static struct dentry *dell_laptop_dir;
static int dell_debugfs_show(struct seq_file *s, void *data)
{
+ int hwswitch_state;
+ int hwswitch_ret;
int status;
+ int ret;
get_buffer();
+
dell_send_request(buffer, 17, 11);
+ ret = buffer->output[0];
status = buffer->output[1];
+
+ clear_buffer();
+
+ buffer->input[0] = 0x2;
+ dell_send_request(buffer, 17, 11);
+ hwswitch_ret = buffer->output[0];
+ hwswitch_state = buffer->output[1];
+
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",
status & BIT(0));
@@ -547,12 +687,21 @@ static int dell_debugfs_show(struct seq_file *s, void *data)
(status & BIT(4)) >> 4);
seq_printf(s, "Bit 5 : Wireless keyboard supported: %lu\n",
(status & BIT(5)) >> 5);
+ seq_printf(s, "Bit 6 : UWB supported: %lu\n",
+ (status & BIT(6)) >> 6);
+ seq_printf(s, "Bit 7 : WiGig supported: %lu\n",
+ (status & BIT(7)) >> 7);
seq_printf(s, "Bit 8 : Wifi is installed: %lu\n",
(status & BIT(8)) >> 8);
seq_printf(s, "Bit 9 : Bluetooth is installed: %lu\n",
(status & BIT(9)) >> 9);
seq_printf(s, "Bit 10: WWAN is installed: %lu\n",
(status & BIT(10)) >> 10);
+ seq_printf(s, "Bit 11: UWB installed: %lu\n",
+ (status & BIT(11)) >> 11);
+ seq_printf(s, "Bit 12: WiGig installed: %lu\n",
+ (status & BIT(12)) >> 12);
+
seq_printf(s, "Bit 16: Hardware switch is on: %lu\n",
(status & BIT(16)) >> 16);
seq_printf(s, "Bit 17: Wifi is blocked: %lu\n",
@@ -561,14 +710,23 @@ static int dell_debugfs_show(struct seq_file *s, void *data)
(status & BIT(18)) >> 18);
seq_printf(s, "Bit 19: WWAN is blocked: %lu\n",
(status & BIT(19)) >> 19);
+ seq_printf(s, "Bit 20: UWB is blocked: %lu\n",
+ (status & BIT(20)) >> 20);
+ seq_printf(s, "Bit 21: WiGig is blocked: %lu\n",
+ (status & BIT(21)) >> 21);
- seq_printf(s, "\nhwswitch_state:\t0x%X\n", hwswitch_state);
+ seq_printf(s, "\nhwswitch_return:\t%d\n", hwswitch_ret);
+ seq_printf(s, "hwswitch_state:\t0x%X\n", hwswitch_state);
seq_printf(s, "Bit 0 : Wifi controlled by switch: %lu\n",
hwswitch_state & BIT(0));
seq_printf(s, "Bit 1 : Bluetooth controlled by switch: %lu\n",
(hwswitch_state & BIT(1)) >> 1);
seq_printf(s, "Bit 2 : WWAN controlled by switch: %lu\n",
(hwswitch_state & BIT(2)) >> 2);
+ seq_printf(s, "Bit 3 : UWB controlled by switch: %lu\n",
+ (hwswitch_state & BIT(3)) >> 3);
+ seq_printf(s, "Bit 4 : WiGig controlled by switch: %lu\n",
+ (hwswitch_state & BIT(4)) >> 4);
seq_printf(s, "Bit 7 : Wireless switch config locked: %lu\n",
(hwswitch_state & BIT(7)) >> 7);
seq_printf(s, "Bit 8 : Wifi locator enabled: %lu\n",
@@ -594,25 +752,43 @@ static const struct file_operations dell_debugfs_fops = {
static void dell_update_rfkill(struct work_struct *ignored)
{
+ int hwswitch = 0;
int status;
+ int ret;
get_buffer();
+
dell_send_request(buffer, 17, 11);
+ ret = buffer->output[0];
status = buffer->output[1];
+ if (ret != 0)
+ goto out;
+
+ clear_buffer();
+
+ buffer->input[0] = 0x2;
+ dell_send_request(buffer, 17, 11);
+ ret = buffer->output[0];
+
+ if (ret == 0 && (status & BIT(0)))
+ hwswitch = buffer->output[1];
+
if (wifi_rfkill) {
- dell_rfkill_update_hw_state(wifi_rfkill, 1, status);
+ dell_rfkill_update_hw_state(wifi_rfkill, 1, status, hwswitch);
dell_rfkill_update_sw_state(wifi_rfkill, 1, status);
}
if (bluetooth_rfkill) {
- dell_rfkill_update_hw_state(bluetooth_rfkill, 2, status);
+ dell_rfkill_update_hw_state(bluetooth_rfkill, 2, status,
+ hwswitch);
dell_rfkill_update_sw_state(bluetooth_rfkill, 2, status);
}
if (wwan_rfkill) {
- dell_rfkill_update_hw_state(wwan_rfkill, 3, status);
+ dell_rfkill_update_hw_state(wwan_rfkill, 3, status, hwswitch);
dell_rfkill_update_sw_state(wwan_rfkill, 3, status);
}
+ out:
release_buffer();
}
static DECLARE_DELAYED_WORK(dell_rfkill_work, dell_update_rfkill);
@@ -641,6 +817,20 @@ static bool dell_laptop_i8042_filter(unsigned char data, unsigned char str,
return false;
}
+static int (*dell_rbtn_notifier_register_func)(struct notifier_block *);
+static int (*dell_rbtn_notifier_unregister_func)(struct notifier_block *);
+
+static int dell_laptop_rbtn_notifier_call(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ schedule_delayed_work(&dell_rfkill_work, 0);
+ return NOTIFY_OK;
+}
+
+static struct notifier_block dell_laptop_rbtn_notifier = {
+ .notifier_call = dell_laptop_rbtn_notifier_call,
+};
+
static int __init dell_setup_rfkill(void)
{
int status, ret, whitelisted;
@@ -660,21 +850,17 @@ static int __init dell_setup_rfkill(void)
get_buffer();
dell_send_request(buffer, 17, 11);
+ ret = buffer->output[0];
status = buffer->output[1];
- buffer->input[0] = 0x2;
- dell_send_request(buffer, 17, 11);
- hwswitch_state = buffer->output[1];
release_buffer();
- if (!(status & BIT(0))) {
- if (force_rfkill) {
- /* No hwsitch, clear all hw-controlled bits */
- hwswitch_state &= ~7;
- } else {
- /* rfkill is only tested on laptops with a hwswitch */
- return 0;
- }
- }
+ /* dell wireless info smbios call is not supported */
+ if (ret != 0)
+ return 0;
+
+ /* rfkill is only tested on laptops with a hwswitch */
+ if (!(status & BIT(0)) && !force_rfkill)
+ return 0;
if ((status & (1<<2|1<<8)) == (1<<2|1<<8)) {
wifi_rfkill = rfkill_alloc("dell-wifi", &platform_device->dev,
@@ -717,10 +903,62 @@ static int __init dell_setup_rfkill(void)
goto err_wwan;
}
- ret = i8042_install_filter(dell_laptop_i8042_filter);
- if (ret) {
- pr_warn("Unable to install key filter\n");
+ /*
+ * Dell Airplane Mode Switch driver (dell-rbtn) supports ACPI devices
+ * which can receive events from HW slider switch.
+ *
+ * Dell SMBIOS on whitelisted models supports controlling radio devices
+ * but does not support receiving HW button switch events. We can use
+ * i8042 filter hook function to receive keyboard data and handle
+ * keycode for HW button.
+ *
+ * So if it is possible we will use Dell Airplane Mode Switch ACPI
+ * driver for receiving HW events and Dell SMBIOS for setting rfkill
+ * states. If ACPI driver or device is not available we will fallback to
+ * i8042 filter hook function.
+ *
+ * To prevent duplicate rfkill devices which control and do same thing,
+ * dell-rbtn driver will automatically remove its own rfkill devices
+ * once function dell_rbtn_notifier_register() is called.
+ */
+
+ dell_rbtn_notifier_register_func =
+ symbol_request(dell_rbtn_notifier_register);
+ if (dell_rbtn_notifier_register_func) {
+ dell_rbtn_notifier_unregister_func =
+ symbol_request(dell_rbtn_notifier_unregister);
+ if (!dell_rbtn_notifier_unregister_func) {
+ symbol_put(dell_rbtn_notifier_register);
+ dell_rbtn_notifier_register_func = NULL;
+ }
+ }
+
+ if (dell_rbtn_notifier_register_func) {
+ ret = dell_rbtn_notifier_register_func(
+ &dell_laptop_rbtn_notifier);
+ symbol_put(dell_rbtn_notifier_register);
+ dell_rbtn_notifier_register_func = NULL;
+ if (ret != 0) {
+ symbol_put(dell_rbtn_notifier_unregister);
+ dell_rbtn_notifier_unregister_func = NULL;
+ }
+ } else {
+ pr_info("Symbols from dell-rbtn acpi driver are not available\n");
+ ret = -ENODEV;
+ }
+
+ if (ret == 0) {
+ pr_info("Using dell-rbtn acpi driver for receiving events\n");
+ } else if (ret != -ENODEV) {
+ pr_warn("Unable to register dell rbtn notifier\n");
goto err_filter;
+ } else {
+ ret = i8042_install_filter(dell_laptop_i8042_filter);
+ if (ret) {
+ pr_warn("Unable to install key filter\n");
+ goto err_filter;
+ }
+ pr_info("Using i8042 filter function for receiving events\n");
}
return 0;
@@ -743,6 +981,14 @@ err_wifi:
static void dell_cleanup_rfkill(void)
{
+ if (dell_rbtn_notifier_unregister_func) {
+ dell_rbtn_notifier_unregister_func(&dell_laptop_rbtn_notifier);
+ symbol_put(dell_rbtn_notifier_unregister);
+ dell_rbtn_notifier_unregister_func = NULL;
+ } else {
+ i8042_remove_filter(dell_laptop_i8042_filter);
+ }
+ cancel_delayed_work_sync(&dell_rfkill_work);
if (wifi_rfkill) {
rfkill_unregister(wifi_rfkill);
rfkill_destroy(wifi_rfkill);
@@ -759,47 +1005,50 @@ static void dell_cleanup_rfkill(void)
static int dell_send_intensity(struct backlight_device *bd)
{
- int ret = 0;
+ int token;
+ int ret;
+
+ token = find_token_location(BRIGHTNESS_TOKEN);
+ if (token == -1)
+ return -ENODEV;
get_buffer();
- buffer->input[0] = find_token_location(BRIGHTNESS_TOKEN);
+ buffer->input[0] = token;
buffer->input[1] = bd->props.brightness;
- if (buffer->input[0] == -1) {
- ret = -ENODEV;
- goto out;
- }
-
if (power_supply_is_system_supplied() > 0)
dell_send_request(buffer, 1, 2);
else
dell_send_request(buffer, 1, 1);
- out:
+ ret = dell_smi_error(buffer->output[0]);
+
release_buffer();
return ret;
}
static int dell_get_intensity(struct backlight_device *bd)
{
- int ret = 0;
+ int token;
+ int ret;
- get_buffer();
- buffer->input[0] = find_token_location(BRIGHTNESS_TOKEN);
+ token = find_token_location(BRIGHTNESS_TOKEN);
+ if (token == -1)
+ return -ENODEV;
- if (buffer->input[0] == -1) {
- ret = -ENODEV;
- goto out;
- }
+ get_buffer();
+ buffer->input[0] = token;
if (power_supply_is_system_supplied() > 0)
dell_send_request(buffer, 0, 2);
else
dell_send_request(buffer, 0, 1);
- ret = buffer->output[1];
+ if (buffer->output[0])
+ ret = dell_smi_error(buffer->output[0]);
+ else
+ ret = buffer->output[1];
- out:
release_buffer();
return ret;
}
@@ -1863,6 +2112,7 @@ static void kbd_led_exit(void)
static int __init dell_init(void)
{
int max_intensity = 0;
+ int token;
int ret;
if (!dmi_check_system(dell_device_table))
@@ -1918,21 +2168,18 @@ static int __init dell_init(void)
debugfs_create_file("rfkill", 0444, dell_laptop_dir, NULL,
&dell_debugfs_fops);
-#ifdef CONFIG_ACPI
- /* In the event of an ACPI backlight being available, don't
- * register the platform controller.
- */
- if (acpi_video_backlight_support())
+ if (acpi_video_get_backlight_type() != acpi_backlight_vendor)
return 0;
-#endif
- get_buffer();
- buffer->input[0] = find_token_location(BRIGHTNESS_TOKEN);
- if (buffer->input[0] != -1) {
+ token = find_token_location(BRIGHTNESS_TOKEN);
+ if (token != -1) {
+ get_buffer();
+ buffer->input[0] = token;
dell_send_request(buffer, 0, 2);
- max_intensity = buffer->output[3];
+ if (buffer->output[0] == 0)
+ max_intensity = buffer->output[3];
+ release_buffer();
}
- release_buffer();
if (max_intensity) {
struct backlight_properties props;
@@ -1959,8 +2206,6 @@ static int __init dell_init(void)
return 0;
fail_backlight:
- i8042_remove_filter(dell_laptop_i8042_filter);
- cancel_delayed_work_sync(&dell_rfkill_work);
dell_cleanup_rfkill();
fail_rfkill:
free_page((unsigned long)buffer);
@@ -1981,8 +2226,6 @@ static void __exit dell_exit(void)
if (quirks && quirks->touchpad_led)
touchpad_led_exit();
kbd_led_exit();
- i8042_remove_filter(dell_laptop_i8042_filter);
- cancel_delayed_work_sync(&dell_rfkill_work);
backlight_device_unregister(dell_backlight_device);
dell_cleanup_rfkill();
if (platform_device) {
@@ -1993,7 +2236,14 @@ static void __exit dell_exit(void)
free_page((unsigned long)buffer);
}
-module_init(dell_init);
+/* dell-rbtn.c driver export functions which will not work correctly (and could
+ * cause kernel crash) if they are called before dell-rbtn.c init code. This is
+ * not problem when dell-rbtn.c is compiled as external module. When both files
+ * (dell-rbtn.c and dell-laptop.c) are compiled statically into kernel, then we
+ * need to ensure that dell_init() will be called after initializing dell-rbtn.
+ * This can be achieved by late_initcall() instead module_init().
+ */
+late_initcall(dell_init);
module_exit(dell_exit);
MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");