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Date: Tue, 20 Nov 2012 15:15:25 +0200
From: Mika Westerberg <mika.westerberg@...ux.intel.com>
To: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: grant.likely@...retlab.ca, linus.walleij@...aro.org,
w.sang@...gutronix.de, rafael.j.wysocki@...el.com,
linux-kernel@...r.kernel.org, lenb@...nel.org,
broonie@...nsource.wolfsonmicro.com, khali@...ux-fr.org,
ben-linux@...ff.org, bhelgaas@...gle.com,
mathias.nyman@...ux.intel.com, linux-acpi@...r.kernel.org
Subject: Re: [PATCH v3 2/3] spi / ACPI: add ACPI enumeration support
On Tue, Nov 20, 2012 at 02:05:26PM +0100, Rafael J. Wysocki wrote:
> On Tuesday, November 20, 2012 12:29:43 PM Mika Westerberg wrote:
> > ACPI 5 introduced SPISerialBus resource that allows us to enumerate and
> > configure the SPI slave devices behind the SPI controller. This patch adds
> > support for this to the SPI core.
> >
> > In addition we bind ACPI nodes to SPI devices. This makes it possible for
> > the slave drivers to get the ACPI handle for further configuration.
> >
> > Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> > ---
> > drivers/spi/spi.c | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 114 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> > index 84c2861..3ae5351 100644
> > --- a/drivers/spi/spi.c
> > +++ b/drivers/spi/spi.c
> > @@ -35,6 +35,8 @@
> > #include <linux/sched.h>
> > #include <linux/delay.h>
> > #include <linux/kthread.h>
> > +#include <linux/ioport.h>
> > +#include <linux/acpi.h>
> >
> > static void spidev_release(struct device *dev)
> > {
> > @@ -93,6 +95,10 @@ static int spi_match_device(struct device *dev, struct device_driver *drv)
> > if (of_driver_match_device(dev, drv))
> > return 1;
> >
> > + /* Then try ACPI */
> > + if (acpi_driver_match_device(dev, drv))
> > + return 1;
> > +
> > if (sdrv->id_table)
> > return !!spi_match_id(sdrv->id_table, spi);
> >
> > @@ -888,6 +894,112 @@ static void of_register_spi_devices(struct spi_master *master)
> > static void of_register_spi_devices(struct spi_master *master) { }
> > #endif
> >
> > +#ifdef CONFIG_ACPI
> > +static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
> > +{
> > + struct acpi_resource_spi_serialbus *sb;
> > + struct spi_device *spi = data;
> > + struct resource r;
> > +
> > + switch (ares->type) {
> > + case ACPI_RESOURCE_TYPE_IRQ:
> > + case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
>
> It is not necessary to check the resource type for IRQ resources here,
> because acpi_dev_resource_interrupt() will do it for you anyway. :-)
>
> So, I would first check if the resource type is ACPI_RESOURCE_TYPE_SERIAL_BUS
> (and populate the spi_device fields if so) and then do something like this:
>
> if (acpi_dev_resource_interrupt(ares, 0, &r)) {
> if (spi->irq < 0)
> spi->irq = r.start;
>
> return 1;
> }
>
> We don't even need to memset(), because we're not going to use that resource
> object going forward.
But doesn't acpi_dev_resource_interrupt() do acpi_register_gsi() and all
that stuff? And we were supposed to avoid that.
>
> > + /* Only use the first interrupt resource and skip the rest */
> > + memset(&r, 0, sizeof(r));
> > + if (spi->irq < 0 && acpi_dev_resource_interrupt(ares, 0, &r))
> > + spi->irq = r.start;
> > + return 1;
> > +
> > + case ACPI_RESOURCE_TYPE_SERIAL_BUS:
> > + sb = &ares->data.spi_serial_bus;
> > + if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
> > + spi->chip_select = sb->device_selection;
> > + spi->max_speed_hz = sb->connection_speed;
> > +
> > + if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
> > + spi->mode |= SPI_CPHA;
> > + if (sb->clock_polarity == ACPI_SPI_START_HIGH)
> > + spi->mode |= SPI_CPOL;
> > + if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
> > + spi->mode |= SPI_CS_HIGH;
> > +
> > + return 1;
> > + }
> > + return 0;
> > + }
> > +
> > + return 0;
>
> We're not interested in any resources except for the above, so I think we
> can just always return 1 from this function, or am I missing anything?
Right you are, we can return 1 always. I'll update this.
> > +}
> > +
> > +static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
> > + void *data, void **return_value)
> > +{
> > + struct spi_master *master = data;
> > + struct list_head resource_list;
> > + struct acpi_device *adev;
> > + struct spi_device *spi;
> > + int ret;
> > +
> > + if (acpi_bus_get_device(handle, &adev))
> > + return AE_OK;
> > + if (acpi_bus_get_status(adev) || !adev->status.present)
> > + return AE_OK;
> > +
> > + spi = spi_alloc_device(master);
> > + if (!spi) {
> > + dev_err(&master->dev, "failed to allocate SPI device for %s\n",
> > + dev_name(&adev->dev));
> > + return AE_NO_MEMORY;
> > + }
> > +
> > + ACPI_HANDLE_SET(&spi->dev, handle);
> > + spi->irq = -1;
> > +
> > + INIT_LIST_HEAD(&resource_list);
> > + ret = acpi_dev_get_resources(adev, &resource_list,
> > + acpi_spi_add_resource, spi);
>
> acpi_dev_free_resource_list(&resource_list); can be done here (the list
> is going to be empty anyway if acpi_spi_add_resource() always returns 1)
> and then you won't need the fail_put_dev label.
OK, but there are still two cases below where we need to do
spi_dev_put(spi). Or do you mean that for each case I just call that
directly instead of goto fail_put_dev?
> > + if (ret < 0)
> > + goto fail_put_dev;
> > +
> > + acpi_dev_free_resource_list(&resource_list);
> > +
> > + if (!spi->max_speed_hz)
> > + goto fail_put_dev;
> > +
> > + strlcpy(spi->modalias, dev_name(&adev->dev), sizeof(spi->modalias));
> > + if (spi_add_device(spi)) {
> > + dev_err(&master->dev, "failed to add SPI device %s from ACPI\n",
> > + dev_name(&adev->dev));
> > + goto fail_put_dev;
> > + }
> > +
> > + return AE_OK;
> > +
> > +fail_put_dev:
> > + spi_dev_put(spi);
> > +
> > + return AE_OK;
> > +}
> > +
> > +static void acpi_register_spi_devices(struct spi_master *master)
> > +{
> > + acpi_status status;
> > + acpi_handle handle;
> > +
> > + handle = ACPI_HANDLE(&master->dev);
> > + if (!handle)
> > + return;
> > +
> > + status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
> > + acpi_spi_add_device, NULL,
> > + master, NULL);
> > + if (ACPI_FAILURE(status))
> > + dev_warn(&master->dev, "failed to enumerate SPI slaves\n");
> > +}
> > +#else
> > +static inline void acpi_register_spi_devices(struct spi_master *master) {}
> > +#endif /* CONFIG_ACPI */
> > +
> > static void spi_master_release(struct device *dev)
> > {
> > struct spi_master *master;
> > @@ -1023,8 +1135,9 @@ int spi_register_master(struct spi_master *master)
> > spi_match_master_to_boardinfo(master, &bi->board_info);
> > mutex_unlock(&board_lock);
> >
> > - /* Register devices from the device tree */
> > + /* Register devices from the device tree and ACPI */
> > of_register_spi_devices(master);
> > + acpi_register_spi_devices(master);
> > done:
> > return status;
> > }
>
> Thanks,
> Rafael
>
>
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.
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