fpga: xilinx-spi: extract a common driver core

Factor out the gpio handshaking (using PROGRAM_B, INIT_B and DONE)
protocol in xilinx-core so that it can be reused for another driver.
This commit does not change anything functionally to xilinx-spi.

xilinx-core expects drivers to provide a write(const char* buf,
size_t count) function that performs the actual write to the device,
as well as a struct device* for resource management.

Signed-off-by: Charles Perry <charles.perry@savoirfairelinux.com>
Acked-by: Xu Yilun <yilun.xu@intel.com>
Link: https://lore.kernel.org/r/20240321220447.3260065-2-charles.perry@savoirfairelinux.com
Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/fpga/xilinx-core.h b/drivers/fpga/xilinx-core.h
new file mode 100644
index 000000000000..f02ac67fce7b
--- /dev/null
+++ b/drivers/fpga/xilinx-core.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __XILINX_CORE_H
+#define __XILINX_CORE_H
+
+#include <linux/device.h>
+
+/**
+ * struct xilinx_fpga_core - interface between the driver and the core manager
+ *                           of Xilinx 7 Series FPGA manager
+ * @dev:       device node
+ * @write:     write callback of the driver
+ */
+struct xilinx_fpga_core {
+/* public: */
+	struct device *dev;
+	int (*write)(struct xilinx_fpga_core *core, const char *buf,
+		     size_t count);
+/* private: handled by xilinx-core */
+	struct gpio_desc *prog_b;
+	struct gpio_desc *init_b;
+	struct gpio_desc *done;
+};
+
+int xilinx_core_probe(struct xilinx_fpga_core *core);
+
+#endif /* __XILINX_CORE_H */