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-rw-r--r--Documentation/laptops/thinkpad-acpi.txt11
-rw-r--r--drivers/platform/x86/Kconfig24
-rw-r--r--drivers/platform/x86/thinkpad_acpi.c76
3 files changed, 91 insertions, 20 deletions
diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt
index de6f14c79070..bce1d959b703 100644
--- a/Documentation/laptops/thinkpad-acpi.txt
+++ b/Documentation/laptops/thinkpad-acpi.txt
@@ -901,6 +901,17 @@ some older ThinkPad models, it is possible to query the status of the
LED indicators as well. Newer ThinkPads cannot query the real status
of the LED indicators.
+Because misuse of the LEDs could induce an unaware user to perform
+dangerous actions (like undocking or ejecting a bay device while the
+buses are still active), or mask an important alarm (such as a nearly
+empty battery, or a broken battery), access to most LEDs is
+restricted.
+
+Unrestricted access to all LEDs requires that thinkpad-acpi be
+compiled with the CONFIG_THINKPAD_ACPI_UNSAFE_LEDS option enabled.
+Distributions must never enable this option. Individual users that
+are aware of the consequences are welcome to enabling it.
+
procfs notes:
The available commands are:
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 3608081bc3e0..d45c6ab729f8 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -226,6 +226,30 @@ config THINKPAD_ACPI_DEBUG
If you are not sure, say N here.
+config THINKPAD_ACPI_UNSAFE_LEDS
+ bool "Allow control of important LEDs (unsafe)"
+ depends on THINKPAD_ACPI
+ default n
+ ---help---
+ Overriding LED state on ThinkPads can mask important
+ firmware alerts (like critical battery condition), or misled
+ the user into damaging the hardware (undocking or ejecting
+ the bay while buses are still active), etc.
+
+ LED control on the ThinkPad is write-only (with very few
+ exceptions on very ancient models), which makes it
+ impossible to know beforehand if important information will
+ be lost when one changes LED state.
+
+ Users that know what they are doing can enable this option
+ and the driver will allow control of every LED, including
+ the ones on the dock stations.
+
+ Never enable this option on a distribution kernel.
+
+ Say N here, unless you are building a kernel for your own
+ use, and need to control the important firmware LEDs.
+
config THINKPAD_ACPI_DOCK
bool "Legacy Docking Station Support"
depends on THINKPAD_ACPI
diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index f003fb7c79ca..38c34c79ff35 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -4657,6 +4657,16 @@ static const char * const tpacpi_led_names[TPACPI_LED_NUMLEDS] = {
"tpacpi::unknown_led",
"tpacpi::standby",
};
+#define TPACPI_SAFE_LEDS 0x0081U
+
+static inline bool tpacpi_is_led_restricted(const unsigned int led)
+{
+#ifdef CONFIG_THINKPAD_ACPI_UNSAFE_LEDS
+ return false;
+#else
+ return (TPACPI_SAFE_LEDS & (1 << led)) == 0;
+#endif
+}
static int led_get_status(const unsigned int led)
{
@@ -4694,16 +4704,20 @@ static int led_set_status(const unsigned int led,
switch (led_supported) {
case TPACPI_LED_570:
/* 570 */
- if (led > 7)
+ if (unlikely(led > 7))
return -EINVAL;
+ if (unlikely(tpacpi_is_led_restricted(led)))
+ return -EPERM;
if (!acpi_evalf(led_handle, NULL, NULL, "vdd",
(1 << led), led_sled_arg1[ledstatus]))
rc = -EIO;
break;
case TPACPI_LED_OLD:
/* 600e/x, 770e, 770x, A21e, A2xm/p, T20-22, X20 */
- if (led > 7)
+ if (unlikely(led > 7))
return -EINVAL;
+ if (unlikely(tpacpi_is_led_restricted(led)))
+ return -EPERM;
rc = ec_write(TPACPI_LED_EC_HLMS, (1 << led));
if (rc >= 0)
rc = ec_write(TPACPI_LED_EC_HLBL,
@@ -4714,6 +4728,10 @@ static int led_set_status(const unsigned int led,
break;
case TPACPI_LED_NEW:
/* all others */
+ if (unlikely(led >= TPACPI_LED_NUMLEDS))
+ return -EINVAL;
+ if (unlikely(tpacpi_is_led_restricted(led)))
+ return -EPERM;
if (!acpi_evalf(led_handle, NULL, NULL, "vdd",
led, led_led_arg1[ledstatus]))
rc = -EIO;
@@ -4806,6 +4824,30 @@ static void led_exit(void)
kfree(tpacpi_leds);
}
+static int __init tpacpi_init_led(unsigned int led)
+{
+ int rc;
+
+ tpacpi_leds[led].led = led;
+
+ tpacpi_leds[led].led_classdev.brightness_set = &led_sysfs_set;
+ tpacpi_leds[led].led_classdev.blink_set = &led_sysfs_blink_set;
+ if (led_supported == TPACPI_LED_570)
+ tpacpi_leds[led].led_classdev.brightness_get =
+ &led_sysfs_get;
+
+ tpacpi_leds[led].led_classdev.name = tpacpi_led_names[led];
+
+ INIT_WORK(&tpacpi_leds[led].work, led_set_status_worker);
+
+ rc = led_classdev_register(&tpacpi_pdev->dev,
+ &tpacpi_leds[led].led_classdev);
+ if (rc < 0)
+ tpacpi_leds[led].led_classdev.name = NULL;
+
+ return rc;
+}
+
static int __init led_init(struct ibm_init_struct *iibm)
{
unsigned int i;
@@ -4839,27 +4881,21 @@ static int __init led_init(struct ibm_init_struct *iibm)
}
for (i = 0; i < TPACPI_LED_NUMLEDS; i++) {
- tpacpi_leds[i].led = i;
-
- tpacpi_leds[i].led_classdev.brightness_set = &led_sysfs_set;
- tpacpi_leds[i].led_classdev.blink_set = &led_sysfs_blink_set;
- if (led_supported == TPACPI_LED_570)
- tpacpi_leds[i].led_classdev.brightness_get =
- &led_sysfs_get;
-
- tpacpi_leds[i].led_classdev.name = tpacpi_led_names[i];
-
- INIT_WORK(&tpacpi_leds[i].work, led_set_status_worker);
-
- rc = led_classdev_register(&tpacpi_pdev->dev,
- &tpacpi_leds[i].led_classdev);
- if (rc < 0) {
- tpacpi_leds[i].led_classdev.name = NULL;
- led_exit();
- return rc;
+ if (!tpacpi_is_led_restricted(i)) {
+ rc = tpacpi_init_led(i);
+ if (rc < 0) {
+ led_exit();
+ return rc;
+ }
}
}
+#ifdef CONFIG_THINKPAD_ACPI_UNSAFE_LEDS
+ if (led_supported != TPACPI_LED_NONE)
+ printk(TPACPI_NOTICE
+ "warning: userspace override of important "
+ "firmware LEDs is enabled\n");
+#endif
return (led_supported != TPACPI_LED_NONE)? 0 : 1;
}