3 files changed, 138 insertions, 0 deletions
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 0581a54cf562..9fdeb3224dd0 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -748,6 +748,27 @@ config THINKPAD_ACPI_HOTKEY_POLL
 	  If you are not sure, say Y here.  The driver enables polling only if
 	  it is strictly necessary to do so.
 
+config INTEL_ATOMISP2_LED
+	tristate "Intel AtomISP2 camera LED driver"
+	depends on GPIOLIB && LEDS_GPIO
+	help
+	  Many Bay Trail and Cherry Trail devices come with a camera attached
+	  to Intel's Image Signal Processor. Linux currently does not have a
+	  driver for these, so they do not work as a camera. Some of these
+	  camera's have a LED which is controlled through a GPIO.
+
+	  Some of these devices have a firmware issue where the LED gets turned
+	  on at boot. This driver will turn the LED off at boot and also allows
+	  controlling the LED (repurposing it) through the sysfs LED interface.
+
+	  Which GPIO is attached to the LED is usually not described in the
+	  ACPI tables, so this driver contains per-system info about the GPIO
+	  inside the driver, this means that this driver only works on systems
+	  the driver knows about.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called intel_atomisp2_led.
+
 config INTEL_ATOMISP2_PM
 	tristate "Intel AtomISP2 dummy / power-management driver"
 	depends on PCI && IOSF_MBI && PM
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 2b85852a1a87..5f823f7eff45 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_SENSORS_HDAPS)	+= hdaps.o
 obj-$(CONFIG_THINKPAD_ACPI)	+= thinkpad_acpi.o
 
 # Intel
+obj-$(CONFIG_INTEL_ATOMISP2_LED)	+= intel_atomisp2_led.o
 obj-$(CONFIG_INTEL_ATOMISP2_PM)		+= intel_atomisp2_pm.o
 obj-$(CONFIG_INTEL_CHT_INT33FE)		+= intel_cht_int33fe.o
 intel_cht_int33fe-objs			:= intel_cht_int33fe_common.o \
diff --git a/drivers/platform/x86/intel_atomisp2_led.c b/drivers/platform/x86/intel_atomisp2_led.c
new file mode 100644
index 000000000000..5935dfca166f
--- /dev/null
+++ b/drivers/platform/x86/intel_atomisp2_led.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver for controlling LEDs for cameras connected to the Intel atomisp2
+ * The main purpose of this driver is to turn off LEDs which are on at boot.
+ *
+ * Copyright (C) 2020 Hans de Goede <hdegoede@redhat.com>
+ */
+
+#include <linux/dmi.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/machine.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+
+/* This must be leds-gpio as the leds-gpio driver binds to the name */
+#define DEV_NAME		"leds-gpio"
+
+static const struct gpio_led atomisp2_leds[] = {
+	{
+		.name = "atomisp2::camera",
+		.default_state  = LEDS_GPIO_DEFSTATE_OFF,
+	},
+};
+
+static const struct gpio_led_platform_data atomisp2_leds_pdata = {
+	.num_leds	= ARRAY_SIZE(atomisp2_leds),
+	.leds		= atomisp2_leds,
+};
+
+static struct gpiod_lookup_table asus_t100ta_lookup = {
+	.dev_id = DEV_NAME,
+	.table = {
+		GPIO_LOOKUP_IDX("INT33FC:02", 8, NULL, 0, GPIO_ACTIVE_HIGH),
+		{ }
+	}
+};
+
+static struct gpiod_lookup_table asus_t100chi_lookup = {
+	.dev_id = DEV_NAME,
+	.table = {
+		GPIO_LOOKUP_IDX("INT33FC:01", 24, NULL, 0, GPIO_ACTIVE_HIGH),
+		{ }
+	}
+};
+
+static const struct dmi_system_id atomisp2_led_systems[] __initconst = {
+	{
+		.matches = {
+			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "T100TA"),
+		},
+		.driver_data = &asus_t100ta_lookup,
+	},
+	{
+		.matches = {
+			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "T200TA"),
+		},
+		.driver_data = &asus_t100ta_lookup,
+	},
+	{
+		.matches = {
+			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "T100CHI"),
+		},
+		.driver_data = &asus_t100chi_lookup,
+	},
+	{} /* Terminating entry */
+};
+MODULE_DEVICE_TABLE(dmi, atomisp2_led_systems);
+
+static struct gpiod_lookup_table *gpio_lookup;
+static struct platform_device *pdev;
+
+static int __init atomisp2_led_init(void)
+{
+	const struct dmi_system_id *system;
+
+	system = dmi_first_match(atomisp2_led_systems);
+	if (!system)
+		return -ENODEV;
+
+	gpio_lookup = system->driver_data;
+	gpiod_add_lookup_table(gpio_lookup);
+
+	pdev = platform_device_register_resndata(NULL,
+						 DEV_NAME, PLATFORM_DEVID_NONE,
+						 NULL, 0, &atomisp2_leds_pdata,
+						 sizeof(atomisp2_leds_pdata));
+	if (IS_ERR(pdev))
+		gpiod_remove_lookup_table(gpio_lookup);
+
+	return PTR_ERR_OR_ZERO(pdev);
+}
+
+static void __exit atomisp2_led_cleanup(void)
+{
+	platform_device_unregister(pdev);
+	gpiod_remove_lookup_table(gpio_lookup);
+}
+
+module_init(atomisp2_led_init);
+module_exit(atomisp2_led_cleanup);
+
+/*
+ * The ACPI INIT method from Asus WMI's code on the T100TA and T200TA turns the
+ * LED on (without the WMI interface allowing further control over the LED).
+ * Ensure we are loaded after asus-nb-wmi so that we turn the LED off again.
+ */
+MODULE_SOFTDEP("pre: asus_nb_wmi");
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com");
+MODULE_DESCRIPTION("Intel atomisp2 camera LED driver");
+MODULE_LICENSE("GPL");