dm: sandbox: Add a SPI emulation uclass
U-Boot includes a SPI emulation driver already but it is not explicit, and
is hidden in the SPI flash code.
Conceptually with sandbox's SPI implementation we have a layer which
creates SPI bus transitions and a layer which interprets them, currently
only for SPI flash. The latter is actually an emulation, and it should be
possible to add more than one emulation - not just SPI flash.
Add a SPI emulation uclass so that other emulations can be plugged in to
support different types of emulated devices on difference buses/chip
selects.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>
diff --git a/include/spi.h b/include/spi.h
index 89949b1..aa0a48e 100644
--- a/include/spi.h
+++ b/include/spi.h
@@ -456,6 +456,35 @@
int (*cs_info)(struct udevice *bus, uint cs, struct spi_cs_info *info);
};
+struct dm_spi_emul_ops {
+ /**
+ * SPI transfer
+ *
+ * This writes "bitlen" bits out the SPI MOSI port and simultaneously
+ * clocks "bitlen" bits in the SPI MISO port. That's just the way SPI
+ * works. Here the device is a slave.
+ *
+ * The source of the outgoing bits is the "dout" parameter and the
+ * destination of the input bits is the "din" parameter. Note that
+ * "dout" and "din" can point to the same memory location, in which
+ * case the input data overwrites the output data (since both are
+ * buffered by temporary variables, this is OK).
+ *
+ * spi_xfer() interface:
+ * @slave: The SPI slave which will be sending/receiving the data.
+ * @bitlen: How many bits to write and read.
+ * @dout: Pointer to a string of bits sent to the device. The
+ * bits are held in a byte array and are sent MSB first.
+ * @din: Pointer to a string of bits that will be sent back to
+ * the master.
+ * @flags: A bitwise combination of SPI_XFER_* flags.
+ *
+ * Returns: 0 on success, not -1 on failure
+ */
+ int (*xfer)(struct udevice *slave, unsigned int bitlen,
+ const void *dout, void *din, unsigned long flags);
+};
+
/**
* spi_find_bus_and_cs() - Find bus and slave devices by number
*
@@ -545,12 +574,28 @@
int spi_cs_info(struct udevice *bus, uint cs, struct spi_cs_info *info);
struct sandbox_state;
+
+/**
+ * sandbox_spi_get_emul() - get an emulator for a SPI slave
+ *
+ * This provides a way to attach an emulated SPI device to a particular SPI
+ * slave, so that xfer() operations on the slave will be handled by the
+ * emulator. If a emulator already exists on that chip select it is returned.
+ * Otherwise one is created.
+ *
+ * @state: Sandbox state
+ * @bus: SPI bus requesting the emulator
+ * @slave: SPI slave device requesting the emulator
+ * @emuip: Returns pointer to emulator
+ * @return 0 if OK, -ve on error
+ */
int sandbox_spi_get_emul(struct sandbox_state *state,
struct udevice *bus, struct udevice *slave,
struct udevice **emulp);
/* Access the serial operations for a device */
#define spi_get_ops(dev) ((struct dm_spi_ops *)(dev)->driver->ops)
+#define spi_emul_get_ops(dev) ((struct dm_spi_emul_ops *)(dev)->driver->ops)
#endif /* CONFIG_DM_SPI */
#endif /* _SPI_H_ */