acpi: Support generation of SPI descriptor

Add a function to write a SPI descriptor to the generated ACPI code.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

drivers/spi/sandbox_spi.c

@@ -21,6 +21,7 @@
 #include <linux/errno.h>
 #include <asm/spi.h>
 #include <asm/state.h>
+#include <dm/acpi.h>
 #include <dm/device-internal.h>
 
 #ifndef CONFIG_SPI_IDLE_VAL
@@ -133,6 +134,15 @@ static int sandbox_spi_get_mmap(struct udevice *dev, ulong *map_basep,
 	return 0;
 }
 
+static int sandbox_spi_get_name(const struct udevice *dev, char *out_name)
+{
+	return acpi_copy_name(out_name, "SSPI");
+}
+
+struct acpi_ops sandbox_spi_acpi_ops = {
+	.get_name	= sandbox_spi_get_name,
+};
+
 static const struct dm_spi_ops sandbox_spi_ops = {
 	.xfer		= sandbox_spi_xfer,
 	.set_speed	= sandbox_spi_set_speed,
@@ -151,4 +161,5 @@ U_BOOT_DRIVER(sandbox_spi) = {
 	.id	= UCLASS_SPI,
 	.of_match = sandbox_spi_ids,
 	.ops	= &sandbox_spi_ops,
+	ACPI_OPS_PTR(&sandbox_spi_acpi_ops)
 };

include/acpi/acpi_device.h

@@ -10,6 +10,7 @@
 #define __ACPI_DEVICE_H
 
 #include <i2c.h>
+#include <spi.h>
 #include <linux/bitops.h>
 
 struct acpi_ctx;
@@ -186,8 +187,11 @@ struct acpi_gpio {
 
 /* ACPI Descriptors for Serial Bus interfaces */
 #define ACPI_SERIAL_BUS_TYPE_I2C		1
+#define ACPI_SERIAL_BUS_TYPE_SPI		2
 #define ACPI_I2C_SERIAL_BUS_REVISION_ID		1 /* TODO: upgrade to 2 */
 #define ACPI_I2C_TYPE_SPECIFIC_REVISION_ID	1
+#define ACPI_SPI_SERIAL_BUS_REVISION_ID		1
+#define ACPI_SPI_TYPE_SPECIFIC_REVISION_ID	1
 
 /**
  * struct acpi_i2c - representation of an ACPI I2C device
@@ -204,6 +208,29 @@ struct acpi_i2c {
 	const char *resource;
 };
 
+/**
+ * struct acpi_spi - representation of an ACPI SPI device
+ *
+ * @device_select: Chip select used by this device (typically 0)
+ * @device_select_polarity: Polarity for the device
+ * @wire_mode: Number of wires used for SPI
+ * @speed: Bus speed in Hz
+ * @data_bit_length: Word length for SPI (typically 8)
+ * @clock_phase: Clock phase to capture data
+ * @clock_polarity: Bus polarity
+ * @resource: Resource name for the SPI controller
+ */
+struct acpi_spi {
+	u16 device_select;
+	enum spi_polarity device_select_polarity;
+	enum spi_wire_mode wire_mode;
+	unsigned int speed;
+	u8 data_bit_length;
+	enum spi_clock_phase clock_phase;
+	enum spi_polarity clock_polarity;
+	const char *resource;
+};
+
 /**
  * acpi_device_path() - Get the full path to an ACPI device
  *
@@ -303,4 +330,16 @@ int acpi_device_write_interrupt_or_gpio(struct acpi_ctx *ctx,
  */
 int acpi_device_write_i2c_dev(struct acpi_ctx *ctx, const struct udevice *dev);
 
+/**
+ * acpi_device_write_spi_dev() - Write a SPI device to ACPI
+ *
+ * This writes a serial bus descriptor for the SPI device so that ACPI can use
+ * it
+ *
+ * @ctx: ACPI context pointer
+ * @dev: SPI device to write
+ * @return 0 if OK, -ve on error
+ */
+int acpi_device_write_spi_dev(struct acpi_ctx *ctx, const struct udevice *dev);
+
 #endif

include/spi.h

@@ -13,8 +13,8 @@
 #include <linux/bitops.h>
 
 /* SPI mode flags */
-#define SPI_CPHA	BIT(0)			/* clock phase */
+#define SPI_CPHA	BIT(0)	/* clock phase (1 = SPI_CLOCK_PHASE_SECOND) */
-#define SPI_CPOL	BIT(1)			/* clock polarity */
+#define SPI_CPOL	BIT(1)	/* clock polarity (1 = SPI_POLARITY_HIGH) */
 #define SPI_MODE_0	(0|0)			/* (original MicroWire) */
 #define SPI_MODE_1	(0|SPI_CPHA)
 #define SPI_MODE_2	(SPI_CPOL|0)

lib/acpi/acpi_device.c

@@ -492,3 +492,127 @@ int acpi_device_write_i2c_dev(struct acpi_ctx *ctx, const struct udevice *dev)
 
 	return ret;
 }
+
+#ifdef CONFIG_SPI
+/* ACPI 6.1 section 6.4.3.8.2.2 - SpiSerialBus() */
+static void acpi_device_write_spi(struct acpi_ctx *ctx, const struct acpi_spi *spi)
+{
+	void *desc_length, *type_length;
+	u16 flags = 0;
+
+	/* Byte 0: Descriptor Type */
+	acpigen_emit_byte(ctx, ACPI_DESCRIPTOR_SERIAL_BUS);
+
+	/* Byte 1+2: Length (filled in later) */
+	desc_length = largeres_write_len_f(ctx);
+
+	/* Byte 3: Revision ID */
+	acpigen_emit_byte(ctx, ACPI_SPI_SERIAL_BUS_REVISION_ID);
+
+	/* Byte 4: Resource Source Index is Reserved */
+	acpigen_emit_byte(ctx, 0);
+
+	/* Byte 5: Serial Bus Type is SPI */
+	acpigen_emit_byte(ctx, ACPI_SERIAL_BUS_TYPE_SPI);
+
+	/*
+	 * Byte 6: Flags
+	 *  [7:2]: 0 => Reserved
+	 *    [1]: 1 => ResourceConsumer
+	 *    [0]: 0 => ControllerInitiated
+	 */
+	acpigen_emit_byte(ctx, BIT(1));
+
+	/*
+	 * Byte 7-8: Type Specific Flags
+	 *   [15:2]: 0 => Reserveda
+	 *      [1]: 0 => ActiveLow, 1 => ActiveHigh
+	 *      [0]: 0 => FourWire, 1 => ThreeWire
+	 */
+	if (spi->wire_mode == SPI_3_WIRE_MODE)
+		flags |= BIT(0);
+	if (spi->device_select_polarity == SPI_POLARITY_HIGH)
+		flags |= BIT(1);
+	acpigen_emit_word(ctx, flags);
+
+	/* Byte 9: Type Specific Revision ID */
+	acpigen_emit_byte(ctx, ACPI_SPI_TYPE_SPECIFIC_REVISION_ID);
+
+	/* Byte 10-11: SPI Type Data Length */
+	type_length = largeres_write_len_f(ctx);
+
+	/* Byte 12-15: Connection Speed */
+	acpigen_emit_dword(ctx, spi->speed);
+
+	/* Byte 16: Data Bit Length */
+	acpigen_emit_byte(ctx, spi->data_bit_length);
+
+	/* Byte 17: Clock Phase */
+	acpigen_emit_byte(ctx, spi->clock_phase);
+
+	/* Byte 18: Clock Polarity */
+	acpigen_emit_byte(ctx, spi->clock_polarity);
+
+	/* Byte 19-20: Device Selection */
+	acpigen_emit_word(ctx, spi->device_select);
+
+	/* Fill in Type Data Length */
+	largeres_fill_len(ctx, type_length);
+
+	/* Byte 21+: ResourceSource String */
+	acpigen_emit_string(ctx, spi->resource);
+
+	/* Fill in SPI Descriptor Length */
+	largeres_fill_len(ctx, desc_length);
+}
+
+/**
+ * acpi_device_set_spi() - Set up an ACPI SPI struct from a device
+ *
+ * The value of @scope is not copied, but only referenced. This implies the
+ * caller has to ensure it stays valid for the lifetime of @spi.
+ *
+ * @dev: SPI device to convert
+ * @spi: Place to put the new structure
+ * @scope: Scope of the SPI device (this is the controller path)
+ * @return 0 (always)
+ */
+static int acpi_device_set_spi(const struct udevice *dev, struct acpi_spi *spi,
+			       const char *scope)
+{
+	struct dm_spi_slave_platdata *plat;
+	struct spi_slave *slave = dev_get_parent_priv(dev);
+
+	plat = dev_get_parent_platdata(slave->dev);
+	memset(spi, '\0', sizeof(*spi));
+	spi->device_select = plat->cs;
+	spi->device_select_polarity = SPI_POLARITY_LOW;
+	spi->wire_mode = SPI_4_WIRE_MODE;
+	spi->speed = plat->max_hz;
+	spi->data_bit_length = slave->wordlen;
+	spi->clock_phase = plat->mode & SPI_CPHA ?
+		 SPI_CLOCK_PHASE_SECOND : SPI_CLOCK_PHASE_FIRST;
+	spi->clock_polarity = plat->mode & SPI_CPOL ?
+		 SPI_POLARITY_HIGH : SPI_POLARITY_LOW;
+	spi->resource = scope;
+
+	return 0;
+}
+
+int acpi_device_write_spi_dev(struct acpi_ctx *ctx, const struct udevice *dev)
+{
+	char scope[ACPI_PATH_MAX];
+	struct acpi_spi spi;
+	int ret;
+
+	ret = acpi_device_scope(dev, scope, sizeof(scope));
+	if (ret)
+		return log_msg_ret("scope", ret);
+	ret = acpi_device_set_spi(dev, &spi, scope);
+	if (ret)
+		return log_msg_ret("set", ret);
+	acpi_device_write_spi(ctx, &spi);
+
+	return 0;
+}
+#endif /* CONFIG_SPI */

test/dm/acpigen.c

@@ -308,3 +308,39 @@ static int dm_test_acpi_i2c(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_acpi_i2c, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test emitting a SPI descriptor */
+static int dm_test_acpi_spi(struct unit_test_state *uts)
+{
+	struct acpi_ctx *ctx;
+	struct udevice *dev;
+	u8 *ptr;
+
+	ut_assertok(alloc_context(&ctx));
+
+	ptr = acpigen_get_current(ctx);
+
+	ut_assertok(uclass_first_device_err(UCLASS_SPI_FLASH, &dev));
+	ut_assertok(acpi_device_write_spi_dev(ctx, dev));
+	ut_asserteq(31, acpigen_get_current(ctx) - ptr);
+	ut_asserteq(ACPI_DESCRIPTOR_SERIAL_BUS, ptr[0]);
+	ut_asserteq(28, get_unaligned((u16 *)(ptr + 1)));
+	ut_asserteq(ACPI_SPI_SERIAL_BUS_REVISION_ID, ptr[3]);
+	ut_asserteq(0, ptr[4]);
+	ut_asserteq(ACPI_SERIAL_BUS_TYPE_SPI, ptr[5]);
+	ut_asserteq(2, ptr[6]);
+	ut_asserteq(0, get_unaligned((u16 *)(ptr + 7)));
+	ut_asserteq(ACPI_SPI_TYPE_SPECIFIC_REVISION_ID, ptr[9]);
+	ut_asserteq(9, get_unaligned((u16 *)(ptr + 10)));
+	ut_asserteq(40000000, get_unaligned((u32 *)(ptr + 12)));
+	ut_asserteq(8, ptr[16]);
+	ut_asserteq(0, ptr[17]);
+	ut_asserteq(0, ptr[18]);
+	ut_asserteq(0, get_unaligned((u16 *)(ptr + 19)));
+	ut_asserteq_str("\\_SB.SPI0", (char *)ptr + 21);
+
+	free_context(&ctx);
+
+	return 0;
+}
+DM_TEST(dm_test_acpi_spi, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);