spi: Use Apple device properties in absence of ACPI resources (8a2e487e) · Commits · 戴 / test

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? */ Reported-by:

Leif Liddy <leif.liddy@gmail.com> Tested-by:

Ronald Tschalär <ronald@innovation.ch> Acked-by:

Mark Brown <broonie@kernel.org> Acked-by:

Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by:

Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by:

Lukas Wunner <lukas@wunner.de> Signed-off-by:

Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/spi/spi.c

+32 −0

Original line number	Diff line number	Diff line
		@@ -40,6 +40,7 @@
		#include <linux/ioport.h>
		#include <linux/acpi.h>
		#include <linux/highmem.h>
		#include <linux/platform_data/x86/apple.h>

		#define CREATE_TRACE_POINTS
		#include <trace/events/spi.h>
		@@ -1693,6 +1694,35 @@ static void of_register_spi_devices(struct spi_controller *ctlr) { }
		#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 *obj;

		if (!x86_apple_machine)
		return;

		if (!acpi_dev_get_property(dev, "spiSclkPeriod", ACPI_TYPE_BUFFER, &obj)
		&& obj->buffer.length >= 4)
		spi->max_speed_hz = NSEC_PER_SEC / (u32 )obj->buffer.pointer;

		if (!acpi_dev_get_property(dev, "spiWordSize", ACPI_TYPE_BUFFER, &obj)
		&& obj->buffer.length == 8)
		spi->bits_per_word = (u64 )obj->buffer.pointer;

		if (!acpi_dev_get_property(dev, "spiBitOrder", ACPI_TYPE_BUFFER, &obj)
		&& obj->buffer.length == 8 && !(u64 )obj->buffer.pointer)
		spi->mode \|= SPI_LSB_FIRST;

		if (!acpi_dev_get_property(dev, "spiSPO", ACPI_TYPE_BUFFER, &obj)
		&& obj->buffer.length == 8 && (u64 )obj->buffer.pointer)
		spi->mode \|= SPI_CPOL;

		if (!acpi_dev_get_property(dev, "spiSPH", ACPI_TYPE_BUFFER, &obj)
		&& obj->buffer.length == 8 && (u64 )obj->buffer.pointer)
		spi->mode \|= SPI_CPHA;
		}

		static int acpi_spi_add_resource(struct acpi_resource ares, void data)
		{
		struct spi_device *spi = data;
		@@ -1766,6 +1796,8 @@ static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
		acpi_spi_add_resource, spi);
		acpi_dev_free_resource_list(&resource_list);

		acpi_spi_parse_apple_properties(spi);

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

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