Re: [PATCH v2] platform/x86: Add driver for INT0002 ACPI device

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Mon, Apr 24, 2017 at 12:40:30PM +0300, Andy Shevchenko wrote:
> +Cc: Mika (that's why left all content + one my comment below)
> 
> On Fri, Apr 21, 2017 at 3:52 PM, Hans de Goede <hdegoede@redhat.com> wrote:
> > Some peripherals on Baytrail and Cherrytrail 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.
> >
> > This commit adds a driver which will bind to that device, call the
> > ACPI event handler for the wakeup and clear the interrupt source
> > avoiding the irq storm.
> >
> > Cc: joeyli <jlee@suse.com>
> > Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> > Tested-by: Takashi Iwai <tiwai@suse.de>
> > ---
> > 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)
> > ---
> >  drivers/platform/x86/Kconfig         |  10 ++
> >  drivers/platform/x86/Makefile        |   1 +
> >  drivers/platform/x86/intel_int0002.c | 214 +++++++++++++++++++++++++++++++++++
> >  3 files changed, 225 insertions(+)
> >  create mode 100644 drivers/platform/x86/intel_int0002.c
> >
> > diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> > index 53afa78..be2ffbd 100644
> > --- a/drivers/platform/x86/Kconfig
> > +++ b/drivers/platform/x86/Kconfig
> > @@ -889,6 +889,16 @@ config INTEL_PMC_CORE
> >           Supported features:
> >                 - SLP_S0_RESIDENCY counter.
> >
> > +config INTEL_INT0002
> > +       tristate "Intel INT0002 Virtual GPIO ACPI device driver"
> > +       depends on X86 && ACPI
> > +       ---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
> > +         ACPI device. This driver implements the clearing of the IRQ.
> > +
> >  config IBM_RTL
> >         tristate "Device driver to enable PRTL support"
> >         depends on PCI
> > diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> > index 6731893..de4ffb5 100644
> > --- a/drivers/platform/x86/Makefile
> > +++ b/drivers/platform/x86/Makefile
> > @@ -51,6 +51,7 @@ obj-$(CONFIG_INTEL_SCU_IPC)   += intel_scu_ipc.o
> >  obj-$(CONFIG_INTEL_SCU_IPC_UTIL) += intel_scu_ipcutil.o
> >  obj-$(CONFIG_INTEL_MFLD_THERMAL) += intel_mid_thermal.o
> >  obj-$(CONFIG_INTEL_IPS)                += intel_ips.o
> > +obj-$(CONFIG_INTEL_INT0002)    += intel_int0002.o
> >  obj-$(CONFIG_XO1_RFKILL)       += xo1-rfkill.o
> >  obj-$(CONFIG_XO15_EBOOK)       += xo15-ebook.o
> >  obj-$(CONFIG_IBM_RTL)          += ibm_rtl.o
> > diff --git a/drivers/platform/x86/intel_int0002.c b/drivers/platform/x86/intel_int0002.c
> > new file mode 100644
> > index 0000000..52aab58
> > --- /dev/null
> > +++ b/drivers/platform/x86/intel_int0002.c
> > @@ -0,0 +1,214 @@
> > +/*
> > + * 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 Baytrail and Cherrytrail 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.
> > + *
> > + * This driver will bind to the INT0002 device, call the ACPI event handler
> > + * for the wakeup and clear the interrupt source avoiding the irq storm.
> > + */
> > +
> > +#include <asm/cpu_device_id.h>
> > +#include <asm/intel-family.h>
> > +#include <linux/acpi.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/pm_runtime.h>
> > +#include <linux/slab.h>
> > +
> > +#define GPE0A_PME_B0_STS_BIT           0x2000
> > +#define GPE0A_PME_B0_EN_BIT            0x2000
> > +#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 */
> > +       {}
> > +};
> > +
> > +struct int0002_data {
> > +       spinlock_t lock;
> > +       struct device *dev;
> > +       const struct x86_cpu_id *cpu_id;
> > +       acpi_handle handle;
> > +       char ev_name[5];
> > +};
> > +
> > +static void int0002_irq_enable(struct int0002_data *data, bool enable)
> > +{
> > +       unsigned long flags;
> > +       u32 gpe_en_reg;
> > +
> > +       spin_lock_irqsave(&data->lock, flags);
> > +
> > +       gpe_en_reg = inl(GPE0A_EN_PORT);
> > +       if (enable)
> > +               gpe_en_reg |= GPE0A_PME_B0_EN_BIT;
> > +       else
> > +               gpe_en_reg &= ~GPE0A_PME_B0_EN_BIT;
> > +       outl(gpe_en_reg, GPE0A_EN_PORT);
> > +
> > +       spin_unlock_irqrestore(&data->lock, flags);
> > +}
> > +
> > +static irqreturn_t int0002_irq_handler(int irq, void *handler_data)
> > +{
> > +       struct int0002_data *data = handler_data;
> > +       u32 gpe_sts_reg;
> > +
> > +       gpe_sts_reg = inl(GPE0A_STS_PORT);
> > +       if (!(gpe_sts_reg & GPE0A_PME_B0_STS_BIT))
> > +               return IRQ_NONE;
> > +
> > +       int0002_irq_enable(data, false);
> > +
> > +       return IRQ_WAKE_THREAD;
> > +}
> > +
> > +static irqreturn_t int0002_irq_thread(int irq, void *handler_data)
> > +{
> > +       struct int0002_data *data = handler_data;
> > +       acpi_status status;
> > +
> > +       /* Don't call ACPI event handler on Baytrail? Taken from Android-x86 */
> > +       if (data->cpu_id->model != INTEL_FAM6_ATOM_SILVERMONT1) {
> > +               status = acpi_evaluate_object(data->handle, data->ev_name,
> > +                                             NULL, NULL);
> > +               if (ACPI_FAILURE(status))
> > +                       dev_err(data->dev, "Error calling %s\n", data->ev_name);
> > +       }
> > +
> > +       /* Ack and then re-enable IRQ */
> > +       outl(GPE0A_PME_B0_STS_BIT, GPE0A_STS_PORT);
> > +       int0002_irq_enable(data, true);
> > +
> > +       return IRQ_HANDLED;
> > +}
> > +
> > +static int int0002_probe(struct platform_device *pdev)
> > +{
> > +       struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
> > +       struct device *dev = &pdev->dev;
> > +       struct int0002_data *data;
> > +       struct acpi_resource *res;
> > +       acpi_status status;
> > +       acpi_handle hdl;
> > +       int irq, ret;
> > +
> > +       data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> > +       if (!data)
> > +               return -ENOMEM;
> > +
> > +       spin_lock_init(&data->lock);
> > +       data->dev = dev;
> > +
> > +       /* Menlow has a different INT0002 device? <sigh> */
> > +       data->cpu_id = x86_match_cpu(int0002_cpu_ids);
> > +       if (!data->cpu_id)
> > +               return -ENODEV;
> > +
> > +       data->handle = ACPI_HANDLE(dev);
> > +       if (!data->handle)
> > +               return -ENODEV;
> > +
> > +       irq = platform_get_irq(pdev, 0);
> > +       if (irq < 0) {
> > +               dev_err(dev, "Error getting IRQ: %d\n", irq);
> > +               return irq;
> > +       }
> > +
> > +       status = acpi_get_event_resources(data->handle, &buf);
> > +       if (ACPI_FAILURE(status)) {
> > +               dev_err(dev, "Error getting acpi event resources\n");
> > +               return -ENODEV;
> > +       }
> > +
> > +       /* Find the "GPIO interrupt" event handler to call upon PME */
> > +       ret = -ENODEV;
> > +       for (res = buf.pointer;
> > +            res && (res->type != ACPI_RESOURCE_TYPE_END_TAG);
> > +            res = ACPI_NEXT_RESOURCE(res)) {
> > +
> > +               if (res->type != ACPI_RESOURCE_TYPE_GPIO ||
> > +                   res->data.gpio.connection_type !=
> > +                   ACPI_RESOURCE_GPIO_TYPE_INT)
> > +                       continue;
> > +
> 
> > +               snprintf(data->ev_name, sizeof(data->ev_name), "_%c%02X",
> > +                       res->data.gpio.triggering ? 'E' : 'L',
> > +                       res->data.gpio.pin_table[0]);
> > +
> > +               status = acpi_get_handle(data->handle, data->ev_name, &hdl);
> > +               if (ACPI_SUCCESS(status)) {
> > +                       ret = 0;
> > +                       break;
> > +               }
> 
> I still think it might make sense to split it to some generic helper
> (same code is used in gpiolib-acpi.c).

I agree and further if this device has _AEI I would investigate how you
could get acpi_gpiochip_request_interrupts() to cope with it.