On Wed, Jun 21, 2017 at 08:05:53PM +0200, Lukas Wunner wrote: > MacBooks and MacBook Pros introduced since 2015 return empty _CRS data > for SPI slaves, causing device initialization to fail. Most of the > information that would normally be conveyed via _CRS is available > through ACPI device properties instead, so take advantage of them. > > The meaning and appropriate usage of the device properties was reverse > engineered by Ronald Tschalär and carried over from these commits > authored by him: > > https://github.com/cb22/macbook12-spi-driver/commit/9a416d699ef4 > https://github.com/cb22/macbook12-spi-driver/commit/0c34936ed9a1 > > According to Ronald, the device properties have the following meaning: > > spiSclkPeriod /* period in ns */ > spiWordSize /* in number of bits */ > spiBitOrder /* 1 = MSB_FIRST, 0 = LSB_FIRST */ > spiSPO /* clock polarity: 0 = low, 1 = high */ > spiSPH /* clock phase: 0 = first, 1 = second */ > spiCSDelay /* delay between cs and receive on reads in 10 us */ > resetA2RUsec /* active-to-receive delay? */ > resetRecUsec /* receive delay? */ > > Cc: Mark Brown <broonie@xxxxxxxxxx> > Cc: Federico Lorenzi <florenzi@xxxxxxxxx> > Cc: Ronald Tschalär <ronald@xxxxxxxxxxxxx> > Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx> > --- > drivers/spi/spi.c | 30 ++++++++++++++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c > index 89254a55eb2e..a4066b75d02b 100644 > --- a/drivers/spi/spi.c > +++ b/drivers/spi/spi.c > @@ -21,6 +21,8 @@ > #include <linux/cache.h> > #include <linux/dma-mapping.h> > #include <linux/dmaengine.h> > +#include <linux/dmi.h> > +#include <linux/math64.h> > #include <linux/mutex.h> > #include <linux/of_device.h> > #include <linux/of_irq.h> > @@ -1685,6 +1687,29 @@ static void of_register_spi_devices(struct spi_master *master) { } > #endif > > #ifdef CONFIG_ACPI > +static void acpi_spi_parse_apple_properties(struct spi_device *spi) > +{ > + struct acpi_device *dev = ACPI_COMPANION(&spi->dev); > + const union acpi_object *o; > + > + if (!acpi_dev_get_property(dev, "spiSclkPeriod", ACPI_TYPE_BUFFER, &o)) > + spi->max_speed_hz = div64_u64(NSEC_PER_SEC, > + *(u64 *)o->buffer.pointer); > + > + if (!acpi_dev_get_property(dev, "spiWordSize", ACPI_TYPE_BUFFER, &o)) > + spi->bits_per_word = *(u64 *)o->buffer.pointer; > + > + if (!acpi_dev_get_property(dev, "spiBitOrder", ACPI_TYPE_BUFFER, &o) && > + !*(u64 *)o->buffer.pointer) > + spi->mode |= SPI_LSB_FIRST; > + if (!acpi_dev_get_property(dev, "spiSPO", ACPI_TYPE_BUFFER, &o) && > + *(u64 *)o->buffer.pointer) > + spi->mode |= SPI_CPOL; > + if (!acpi_dev_get_property(dev, "spiSPH", ACPI_TYPE_BUFFER, &o) && > + *(u64 *)o->buffer.pointer) > + spi->mode |= SPI_CPHA; > +} > + > static int acpi_spi_add_resource(struct acpi_resource *ares, void *data) > { > struct spi_device *spi = data; > @@ -1758,6 +1783,11 @@ static acpi_status acpi_register_spi_device(struct spi_master *master, > acpi_spi_add_resource, spi); > acpi_dev_free_resource_list(&resource_list); > > + /* Zero ACPI resources? Try Apple device properties instead. */ > + if (!ret && IS_ENABLED(CONFIG_X86) && > + dmi_match(DMI_SYS_VENDOR, "Apple Inc.")) > + acpi_spi_parse_apple_properties(spi); Same comment here, move the conditionals to acpi_spi_parse_apple_properties() and then do if (!ret) acpi_spi_parse_apple_properties(spi); -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
