[PATCH v5] gpio: Add driver for ACPI INT0002 Virtual GPIO device

Hans de Goede
2017-05-24T10:42:20Z

Some peripherals on Bay Trail and Cherry Trail platforms signal PME to the
PMC to wakeup the system. When this happens software needs to clear the
PME_B0_STS bit in the GPE0a_STS register to avoid an IRQ storm on IRQ 9.

This is modeled in ACPI through the INT0002 ACPI Virtual GPIO device.

This commit adds a driver which registers the Virtual GPIOs expected
by the DSDT on these devices, letting gpiolib-acpi claim the
virtual GPIO and install a GPIO-interrupt handler which call the _L02
handler as it would for a real GPIO controller.

Cc: joeyli <jlee@suse.com>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
Changes in v2:
-Remove dev_err after malloc failure
-Remove unused empty runtime pm callbacks
-s/GPE0A_PME_/GPE0A_PME_B0_/
-Fixed some checkpatch warnings (I forgot to run checkpatch on v1)
Changes in v3:
-Rewrite as gpiochip driver letting gpiolib-acpi deal with claiming the pin
0x0002 and calling the _L02 event handler when the virtual gpio-irq triggers
-Rebase on 4.12-rc1
Changes in v4:
-Drop device_init_wakeup() from _probe(), use pm_system_wakeup() instead
of pm_wakeup_hard_event(chip->parent)
-Improve commit message
Changes in v5:
-Use BIT() macro for FOO_BIT defines
-Drop unneeded ACPI_PTR macro usage
---
drivers/gpio/Kconfig | 14 +++
drivers/gpio/Makefile | 1 +
drivers/gpio/gpio-int0002.c | 210 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 225 insertions(+)
create mode 100644 drivers/gpio/gpio-int0002.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 23ca51ee6b28..11e7f9b464d4 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -608,6 +608,20 @@ config GPIO_GPIO_MM
The base port addresses for the devices may be configured via the base
array module parameter.

+config GPIO_INT0002
+ tristate "Intel ACPI INT0002 Virtual GPIO"
+ depends on ACPI
+ select GPIOLIB_IRQCHIP
+ ---help---
+ Some peripherals on Baytrail and Cherrytrail platforms signal
+ PME to the PMC to wakeup the system. When this happens software
+ needs to explicitly clear the interrupt source to avoid an IRQ
+ storm on IRQ 9. This is modelled in ACPI through the INT0002
+ Virtual GPIO ACPI device.
+
+ To compile this driver as a module, choose M here: the module will
+ be called gpio_int0002.
+
config GPIO_IT87
tristate "IT87xx GPIO support"
help
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 68b96277d9fa..1f76c5694079 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -55,6 +55,7 @@ obj-$(CONFIG_GPIO_GPIO_MM) += gpio-gpio-mm.o
obj-$(CONFIG_GPIO_GRGPIO) += gpio-grgpio.o
obj-$(CONFIG_HTC_EGPIO) += gpio-htc-egpio.o
obj-$(CONFIG_GPIO_ICH) += gpio-ich.o
+obj-$(CONFIG_GPIO_INT0002) += gpio-int0002.o
obj-$(CONFIG_GPIO_IOP) += gpio-iop.o
obj-$(CONFIG_GPIO_IT87) += gpio-it87.o
obj-$(CONFIG_GPIO_JANZ_TTL) += gpio-janz-ttl.o
diff --git a/drivers/gpio/gpio-int0002.c b/drivers/gpio/gpio-int0002.c
new file mode 100644
index 000000000000..50b4e0a213d0
--- /dev/null
+++ b/drivers/gpio/gpio-int0002.c
@@ -0,0 +1,210 @@
+/*
+ * Intel INT0002 "Virtual GPIO" driver
+ *
+ * Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
+ *
+ * Loosely based on android x86 kernel code which is:
+ *
+ * Copyright (c) 2014, Intel Corporation.
+ *
+ * Author: Dyut Kumar Sil <dyut.k.sil@intel.com>
+ *
+ * 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.
+ *
+ * Some peripherals on Bay Trail and Cherry Trail platforms signal PME to the
+ * PMC to wakeup the system. When this happens software needs to clear the
+ * PME_B0_STS bit in the GPE0a_STS register to avoid an IRQ storm on IRQ 9.
+ *
+ * This is modelled in ACPI through the INT0002 ACPI device, which is
+ * called a "Virtual GPIO controller" in ACPI because it defines the event
+ * handler to call when the PME triggers through _AEI and _L02 / _E02
+ * methods as would be done for a real GPIO interrupt in ACPI.
+ *
+ * This driver will bind to the INT0002 device, and register as a GPIO
+ * controller, letting gpiolib-acpi.c call the _L02 handler as it would
+ * for a real GPIO controller.
+ */
+
+#include <asm/cpu_device_id.h>
+#include <asm/intel-family.h>
+#include <linux/acpi.h>
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/suspend.h>
+
+#define DRV_NAME "INT0002 Virtual GPIO"
+
+/* For some reason the virtual GPIO pin tied to the GPE is numbered pin 2 */
+#define GPE0A_PME_B0_VIRT_GPIO_PIN 2
+
+#define GPE0A_PME_B0_STS_BIT BIT(13)
+#define GPE0A_PME_B0_EN_BIT BIT(13)
+#define GPE0A_STS_PORT 0x420
+#define GPE0A_EN_PORT 0x428
+
+#define ICPU(model) { X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, }
+
+static const struct x86_cpu_id int0002_cpu_ids[] = {
+/*
+ * Limit ourselves to Cherry Trail for now, until testing shows we
+ * need to handle the INT0002 device on Baytrail too.
+ * ICPU(INTEL_FAM6_ATOM_SILVERMONT1), * Valleyview, Bay Trail *
+ */
+ ICPU(INTEL_FAM6_ATOM_AIRMONT), /* Braswell, Cherry Trail */
+ {}
+};
+
+static int int0002_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+ return 0;
+}
+
+static void int0002_gpio_set(struct gpio_chip *chip, unsigned int offset,
+ int value)
+{
+}
+
+static int int0002_gpio_direction_output(struct gpio_chip *chip,
+ unsigned int offset, int value)
+{
+ return 0;
+}
+
+static void int0002_irq_ack(struct irq_data *data)
+{
+ outl(GPE0A_PME_B0_STS_BIT, GPE0A_STS_PORT);
+}
+
+static void int0002_irq_unmask(struct irq_data *data)
+{
+ u32 gpe_en_reg;
+
+ gpe_en_reg = inl(GPE0A_EN_PORT);
+ gpe_en_reg |= GPE0A_PME_B0_EN_BIT;
+ outl(gpe_en_reg, GPE0A_EN_PORT);
+}
+
+static void int0002_irq_mask(struct irq_data *data)
+{
+ u32 gpe_en_reg;
+
+ gpe_en_reg = inl(GPE0A_EN_PORT);
+ gpe_en_reg &= ~GPE0A_PME_B0_EN_BIT;
+ outl(gpe_en_reg, GPE0A_EN_PORT);
+}
+
+static irqreturn_t int0002_irq(int irq, void *data)
+{
+ struct gpio_chip *chip = data;
+ u32 gpe_sts_reg;
+
+ gpe_sts_reg = inl(GPE0A_STS_PORT);
+ if (!(gpe_sts_reg & GPE0A_PME_B0_STS_BIT))
+ return IRQ_NONE;
+
+ generic_handle_irq(irq_find_mapping(chip->irqdomain,
+ GPE0A_PME_B0_VIRT_GPIO_PIN));
+
+ pm_system_wakeup();
+
+ return IRQ_HANDLED;
+}
+
+static struct irq_chip int0002_irqchip = {
+ .name = DRV_NAME,
+ .irq_ack = int0002_irq_ack,
+ .irq_mask = int0002_irq_mask,
+ .irq_unmask = int0002_irq_unmask,
+};
+
+static int int0002_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ const struct x86_cpu_id *cpu_id;
+ struct gpio_chip *chip;
+ int i, irq, ret;
+
+ /* Menlow has a different INT0002 device? <sigh> */
+ cpu_id = x86_match_cpu(int0002_cpu_ids);
+ if (!cpu_id)
+ return -ENODEV;
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0) {
+ dev_err(dev, "Error getting IRQ: %d\n", irq);
+ return irq;
+ }
+
+ chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+ if (!chip)
+ return -ENOMEM;
+
+ chip->label = DRV_NAME;
+ chip->parent = dev;
+ chip->owner = THIS_MODULE;
+ chip->get = int0002_gpio_get;
+ chip->set = int0002_gpio_set;
+ chip->direction_input = int0002_gpio_get;
+ chip->direction_output = int0002_gpio_direction_output;
+ chip->base = -1;
+ chip->ngpio = GPE0A_PME_B0_VIRT_GPIO_PIN + 1;
+ chip->irq_need_valid_mask = true;
+
+ ret = devm_gpiochip_add_data(&pdev->dev, chip, NULL);
+ if (ret) {
+ dev_err(dev, "Error adding gpio chip: %d\n", ret);
+ return ret;
+ }
+
+ for (i = 0; i < GPE0A_PME_B0_VIRT_GPIO_PIN; i++)
+ clear_bit(i, chip->irq_valid_mask);
+
+ /*
+ * We manually request the irq here instead of passing a flow-handler
+ * to gpiochip_set_chained_irqchip, because the irq is shared.
+ */
+ ret = devm_request_irq(dev, irq, int0002_irq,
+ IRQF_SHARED | IRQF_NO_THREAD, "INT0002", chip);
+ if (ret) {
+ dev_err(dev, "Error requesting IRQ %d: %d\n", irq, ret);
+ return ret;
+ }
+
+ ret = gpiochip_irqchip_add(chip, &int0002_irqchip, 0, handle_edge_irq,
+ IRQ_TYPE_NONE);
+ if (ret) {
+ dev_err(dev, "Error adding irqchip: %d\n", ret);
+ return ret;
+ }
+
+ gpiochip_set_chained_irqchip(chip, &int0002_irqchip, irq, NULL);
+
+ return 0;
+}
+
+static const struct acpi_device_id int0002_acpi_ids[] = {
+ { "INT0002", 0 },
+ { },
+};
+MODULE_DEVICE_TABLE(acpi, int0002_acpi_ids);
+
+static struct platform_driver int0002_driver = {
+ .driver = {
+ .name = DRV_NAME,
+ .acpi_match_table = int0002_acpi_ids,
+ },
+ .probe = int0002_probe,
+};
+
+module_platform_driver(int0002_driver);
+
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_DESCRIPTION("Intel INT0002 Virtual GPIO driver");
+MODULE_LICENSE("GPL");
--
2.13.0