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); + if (ret < 0 || !spi->max_speed_hz) { spi_dev_put(spi); return AE_OK; -- 2.11.0 -- 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
