bsps/imxrt: Add ioctl to LPSPI to get registers

This allows an application to get the registers of the LPSPI. That is
usefull for applications that want to use DMA for a very specialized and
highly optimized communication.

Update #4180

bsps/arm/imxrt/include/imxrt/lpspi.h

@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/*
+ * Copyright (C) 2020 embedded brains GmbH (http://www.embedded-brains.de)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef LIBBSP_ARM_IMXRT_IMXRT_LPSPI_H
+#define LIBBSP_ARM_IMXRT_IMXRT_LPSPI_H
+
+#include <sys/ioccom.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+#define IMXRT_LPSPI_IOC_MAGIC 's'
+
+/**
+ * @brief Fetch the raw registers.
+ *
+ * This allows to do some special operations. Note that if you do something
+ * fancy, you should lock the hardware by obtaining the bus with the
+ * SPI_BUS_OBTAIN ioctl first. With that, the normal driver can't be used by
+ * other tasks. Also note that you should leave the registers in a clean state
+ * before releasing the bus again.
+ */
+#define IMXRT_LPSPI_GET_REGISTERS _IOR(IMXRT_LPSPI_IOC_MAGIC, 0, LPSPI_Type *)
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+#endif /* LIBBSP_ARM_IMXRT_IMXRT_LPSPI_H */

bsps/arm/imxrt/spi/imxrt-lpspi.c

@@ -34,6 +34,7 @@
 #include <dev/spi/spi.h>
 #include <fsl_clock.h>
 #include <libfdt.h>
+#include <imxrt/lpspi.h>
 
 struct imxrt_lpspi_bus {
   spi_bus base;
@@ -471,6 +472,24 @@ static clock_ip_name_t imxrt_lpspi_clock_ip(volatile LPSPI_Type *regs)
   return kCLOCK_IpInvalid;
 }
 
+static int imxrt_lpspi_ioctl(spi_bus *base, ioctl_command_t command, void *arg)
+{
+  struct imxrt_lpspi_bus *bus;
+  bus = (struct imxrt_lpspi_bus *) base;
+  int err = 0;
+
+  switch (command) {
+    case IMXRT_LPSPI_GET_REGISTERS:
+      *(volatile LPSPI_Type**)arg = bus->regs;
+      break;
+    default:
+      err = -EINVAL;
+      break;
+  }
+
+  return err;
+}
+
 void imxrt_lpspi_init(void)
 {
   const void *fdt;
@@ -523,6 +542,7 @@ void imxrt_lpspi_init(void)
       bus->base.transfer = imxrt_lpspi_transfer;
       bus->base.destroy = imxrt_lpspi_destroy;
       bus->base.setup = imxrt_lpspi_setup;
+      bus->base.ioctl = imxrt_lpspi_ioctl;
 
       eno = spi_bus_register(&bus->base, bus_path);
       if (eno != 0) {

spec/build/bsps/arm/imxrt/bspimxrt.yml

@@ -103,6 +103,7 @@ install:
   source:
   - bsps/arm/imxrt/include/imxrt/imxrt1050.dtsi
   - bsps/arm/imxrt/include/imxrt/imxrt1050-pinfunc.h
+  - bsps/arm/imxrt/include/imxrt/lpspi.h
   - bsps/arm/imxrt/include/imxrt/memory.h
   - bsps/arm/imxrt/include/imxrt/mpu-config.h
 - destination: ${BSP_LIBDIR}