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Subject[PATCH v5 3/3] dell-laptop: Use dell-rbtn instead i8042 filter when possible
Date
Until now module dell-laptop registered rfkill device which used i8042
filter function for receiving HW switch rfkill events (handling special
keycode).

But for some dell laptops there is native ACPI driver dell-rbtn which can
receive rfkill events (without i8042 hooks).

So this patch will combine best from both sides. It will use native ACPI
driver dell-rbtn for receiving events and dell-laptop SMBIOS interface for
enabling or disabling radio devices. If ACPI driver or device will not be
available fallback to i8042 filter function will be used.

Patch also changes module_init() to late_initcall() to ensure that init
function will be called after initializing dell-rbtn.c driver.

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
---
Changes vor v5:
* fixed long lines
---
drivers/platform/x86/dell-laptop.c | 94 +++++++++++++++++++++++++++++++++---
1 file changed, 86 insertions(+), 8 deletions(-)

diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index d688d80..83e3d7f 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -32,6 +32,7 @@
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include "../../firmware/dcdbas.h"
+#include "dell-rbtn.h"

#define BRIGHTNESS_TOKEN 0x7d
#define KBD_LED_OFF_TOKEN 0x01E1
@@ -642,6 +643,20 @@ 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;
@@ -718,10 +733,62 @@ 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;
@@ -744,6 +811,14 @@ 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);
@@ -1961,8 +2036,6 @@ 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)bufferpage);
@@ -1983,8 +2056,6 @@ 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) {
@@ -1995,7 +2066,14 @@ 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>");
--
1.7.9.5


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