v4.19.13 snapshot.
diff --git a/include/linux/spi/mcp23s08.h b/include/linux/spi/mcp23s08.h
new file mode 100644
index 0000000..738a45b
--- /dev/null
+++ b/include/linux/spi/mcp23s08.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+struct mcp23s08_platform_data {
+ /* For mcp23s08, up to 4 slaves (numbered 0..3) can share one SPI
+ * chipselect, each providing 1 gpio_chip instance with 8 gpios.
+ * For mpc23s17, up to 8 slaves (numbered 0..7) can share one SPI
+ * chipselect, each providing 1 gpio_chip (port A + port B) with
+ * 16 gpios.
+ */
+ u32 spi_present_mask;
+
+ /* "base" is the number of the first GPIO or -1 for dynamic
+ * assignment. If there are gaps in chip addressing the GPIO
+ * numbers are sequential .. so for example if only slaves 0
+ * and 3 are present, their GPIOs range from base to base+15
+ * (or base+31 for s17 variant).
+ */
+ unsigned base;
+};