From 896fcd43b074b43ef8bc2db9e860f12f2afcc3eb Mon Sep 17 00:00:00 2001
From: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Date: Fri, 13 Mar 2020 17:29:52 +0100
Subject: [PATCH] drivers/periph/spi: add periph_spi_reconfigure feature

---
 drivers/include/periph/spi.h | 69 +++++++++++++++++++++++++++++++++++-
 kconfigs/Kconfig.features    |  5 +++
 2 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/drivers/include/periph/spi.h b/drivers/include/periph/spi.h
index 1ee88bee29..f5b70aa21a 100644
--- a/drivers/include/periph/spi.h
+++ b/drivers/include/periph/spi.h
@@ -203,7 +203,6 @@ void spi_init(spi_t bus);
 /**
  * @brief   Initialize the used SPI bus pins, i.e. MISO, MOSI, and CLK
  *
- *
  * After calling spi_init, the pins must be initialized (i.e. spi_init is
  * calling this function internally). In normal cases, this function will not be
  * used. But there are some devices (e.g. CC110x), that use SPI bus lines also
@@ -211,6 +210,9 @@ void spi_init(spi_t bus);
  * more of the used pins. So they can take control over certain pins and return
  * control back to the SPI driver using this function.
  *
+ * This function must be called after @ref spi_deinit_pins to return the pins to
+ * SPI operation.
+ *
  * The pins used are configured in the board's periph_conf.h.
  *
  * @param[in] bus       SPI device the pins are configure for
@@ -238,6 +240,71 @@ void spi_init_pins(spi_t bus);
  */
 int spi_init_cs(spi_t bus, spi_cs_t cs);
 
+#if defined(MODULE_PERIPH_SPI_RECONFIGURE) || DOXYGEN
+
+/**
+ * @brief   Change the pins of the given SPI bus back to plain GPIO functionality
+ *
+ * The pin mux of the MISO, MOSI and CLK pins of the bus will be changed back to
+ * default (GPIO) mode and the SPI bus is powered off.
+ * This allows to use the SPI pins for another function and return to SPI
+ * functionality again by calling spi_init_pins()
+ *
+ * If you want the pin to be in a defined state, call gpio_init() on it.
+ *
+ * The bus MUST not be acquired before initializing it, as this is handled
+ * internally by the spi_deinit_pins() function!
+ *
+ * Calls to spi_acquire() will block until spi_init_pins() is called again.
+ *
+ * @note Until this is implemented on all platforms, this requires the
+ *       periph_spi_reconfigure feature to be used.
+ *
+ * @param[in] dev       the device to de-initialize
+ */
+void spi_deinit_pins(spi_t dev);
+
+#if DOXYGEN
+
+/**
+ * @brief   Get the MISO pin of the given SPI bus.
+ *
+ * @param[in] dev       The device to query
+ *
+ * @note Until this is implemented on all platforms, this requires the
+ *       periph_spi_reconfigure feature to be used.
+ *
+ * @return              The GPIO used for the SPI MISO line.
+ */
+gpio_t spi_pin_miso(spi_t dev);
+
+/**
+ * @brief   Get the MOSI pin of the given SPI bus.
+ *
+ * @param[in] dev       The device to query
+ *
+ * @note Until this is implemented on all platforms, this requires the
+ *       periph_spi_reconfigure feature to be used.
+ *
+ * @return              The GPIO used for the SPI MOSI line.
+ */
+gpio_t spi_pin_mosi(spi_t dev);
+
+/**
+ * @brief   Get the CLK pin of the given SPI bus.
+ *
+ * @param[in] dev       The device to query
+ *
+ * @note Until this is implemented on all platforms, this requires the
+ *       periph_spi_reconfigure feature to be used.
+ *
+ * @return              The GPIO used for the SPI CLK line.
+ */
+gpio_t spi_pin_clk(spi_t dev);
+
+#endif /* DOXYGEN */
+#endif /* MODULE_PERIPH_SPI_RECONFIGURE */
+
 #if defined(MODULE_PERIPH_SPI_GPIO_MODE) || DOXYGEN
 
 /**
diff --git a/kconfigs/Kconfig.features b/kconfigs/Kconfig.features
index 99325a000e..72663241ec 100644
--- a/kconfigs/Kconfig.features
+++ b/kconfigs/Kconfig.features
@@ -195,6 +195,11 @@ config HAS_PERIPH_SPI
     help
         Indicates that an SPI peripheral is present.
 
+config HAS_PERIPH_SPI_RECONFIGURE
+    bool
+    help
+        Indicates that the SPI peripheral allows pin reconfiguration.
+
 config HAS_PERIPH_SPI_GPIO_MODE
     bool
     help