Merge pull request #13421 from benpicco/cpu/sam0_common/i2c-deinit

drivers/periph/i2c: add periph_i2c_reconfigure feature & implementation for sam0

cpu/sam0_common/Makefile.features

@@ -3,6 +3,7 @@ FEATURES_PROVIDED += periph_flashpage
 FEATURES_PROVIDED += periph_flashpage_raw
 FEATURES_PROVIDED += periph_flashpage_rwee
 FEATURES_PROVIDED += periph_gpio periph_gpio_irq
+FEATURES_PROVIDED += periph_i2c_reconfigure
 FEATURES_PROVIDED += periph_uart_modecfg
 FEATURES_PROVIDED += periph_uart_nonblocking
 FEATURES_PROVIDED += periph_wdt periph_wdt_cb

cpu/sam0_common/include/periph_cpu_common.h

@@ -300,6 +300,15 @@ typedef enum {
     I2C_SPEED_HIGH      = 3400000U,    /**< high speed mode:   ~3.4Mbit/s */
 } i2c_speed_t;
 /** @} */
+
+/**
+ * @name    I2C pin getter functions
+ * @{
+ */
+#define i2c_pin_sda(dev) i2c_config[dev].sda_pin
+#define i2c_pin_scl(dev) i2c_config[dev].scl_pin
+/** @} */
+
 #endif /* ndef DOXYGEN */
 
 /**

cpu/sam0_common/periph/i2c.c

@@ -79,6 +79,7 @@ void i2c_init(i2c_t dev)
     int32_t tmp_baud;
 
     assert(dev < I2C_NUMOF);
+
     /* Initialize mutex */
     mutex_init(&locks[dev]);
     /* DISABLE I2C MASTER */
@@ -171,6 +172,31 @@ void i2c_release(i2c_t dev)
     mutex_unlock(&locks[dev]);
 }
 
+#ifdef MODULE_PERIPH_I2C_RECONFIGURE
+void i2c_init_pins(i2c_t dev)
+{
+    assert(dev < I2C_NUMOF);
+
+    _i2c_poweron(dev);
+
+    gpio_init_mux(i2c_config[dev].scl_pin, i2c_config[dev].mux);
+    gpio_init_mux(i2c_config[dev].sda_pin, i2c_config[dev].mux);
+
+    mutex_unlock(&locks[dev]);
+}
+
+void i2c_deinit_pins(i2c_t dev)
+{
+    assert(dev < I2C_NUMOF);
+
+    mutex_lock(&locks[dev]);
+    _i2c_poweroff(dev);
+
+    gpio_disable_mux(i2c_config[dev].sda_pin);
+    gpio_disable_mux(i2c_config[dev].scl_pin);
+}
+#endif
+
 int i2c_read_bytes(i2c_t dev, uint16_t addr,
                    void *data, size_t len, uint8_t flags)
 {

drivers/include/periph/i2c.h

@@ -215,6 +215,67 @@ typedef enum {
  */
 void i2c_init(i2c_t dev);
 
+/**
+ * @brief   Initialize the used I2C bus pins
+ *
+ * After calling i2c_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. ATECC608A), that use I2C bus lines also
+ * for other purposes and need the option to dynamically re-configure one or
+ * more of the used pins.
+ *
+ * @param[in] dev       I2C device the pins are configure for
+ */
+void i2c_init_pins(i2c_t dev);
+
+/**
+ * @brief   Change the pins of the given I2C bus back to plain GPIO functionality
+ *
+ * The pin mux of the SDA and SCL pins of the bus will be changed back to
+ * default (GPIO) mode and the I2C bus is powered off.
+ * This allows to use the I2C pins for another function and return to I2C
+ * functionality again by calling i2c_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 i2c_deinit function!
+ *
+ * Calls to i2c_acquire() will block until i2c_init_pins() is called.
+ *
+ * @note Until this is implemented on all platforms, this requires the
+ *       periph_i2c_reconfigure feature to be used.
+ *
+ * @param[in] dev       the device to de-initialize
+ */
+void i2c_deinit_pins(i2c_t dev);
+
+#if DOXYGEN /* functions to be implemented as `#define` in `periph_cpu.h` */
+/**
+ * @brief   Get the SDA pin of the given I2C bus.
+ *
+ * @param[in] dev       The device to query
+ *
+ * @note Until this is implemented on all platforms, this requires the
+ *       periph_i2c_reconfigure feature to be used.
+ *
+ * @return              The GPIO used for the I2C data line.
+ */
+gpio_t i2c_pin_sda(i2c_t dev);
+
+/**
+ * @brief   Get the SCL pin of the given I2C bus.
+ *
+ * @param[in] dev       The device to query
+ *
+ * @note Until this is implemented on all platforms, this requires the
+ *       periph_i2c_reconfigure feature to be used.
+ *
+ * @return              The GPIO used for the I2C clock line.
+ */
+gpio_t i2c_pin_scl(i2c_t dev);
+#endif /* DOXYGEN */
+
 /**
  * @brief   Get mutually exclusive access to the given I2C bus
  *

tests/periph_i2c/Makefile

@@ -2,7 +2,9 @@ BOARD ?= samr21-xpro
 include ../Makefile.tests_common
 
 FEATURES_REQUIRED = periph_i2c
+FEATURES_OPTIONAL = periph_i2c_reconfigure
 
 USEMODULE += shell
+USEMODULE += xtimer
 
 include $(RIOTBASE)/Makefile.include

tests/periph_i2c/main.c

@@ -24,9 +24,12 @@
 #include <errno.h>
 
 #include "periph_conf.h"
+#include "periph/gpio.h"
 #include "periph/i2c.h"
 #include "shell.h"
 
+#include <xtimer.h>
+
 #ifndef I2C_ACK
 #define I2C_ACK         (0)
 #endif
@@ -160,6 +163,47 @@ int cmd_i2c_release(int argc, char **argv)
     return 0;
 }
 
+#ifdef MODULE_PERIPH_I2C_RECONFIGURE
+int cmd_i2c_gpio(int argc, char **argv)
+{
+    int dev;
+
+    dev = _check_param(argc, argv, 1, 1, "DEV");
+    if (dev == ARG_ERROR) {
+        return 1;
+    }
+
+    gpio_t sda_pin = i2c_pin_sda(dev);
+    gpio_t scl_pin = i2c_pin_scl(dev);
+
+    printf("Command: i2c_deinit_pins(%i)\n", dev);
+    i2c_deinit_pins(dev);
+
+    gpio_init(sda_pin, GPIO_OUT);
+    gpio_init(scl_pin, GPIO_OUT);
+
+    xtimer_sleep(1);
+
+    printf("Command: gpio_set()\n");
+    gpio_set(sda_pin);
+    gpio_set(scl_pin);
+
+    xtimer_sleep(1);
+
+    printf("Command: gpio_clear()\n");
+    gpio_clear(sda_pin);
+    gpio_clear(scl_pin);
+
+    xtimer_sleep(1);
+
+    printf("Command: i2c_init_pins(%i)\n", dev);
+    i2c_init_pins(dev);
+
+    printf("Success: i2c_%i re-init\n", dev);
+    return 0;
+}
+#endif
+
 int cmd_i2c_read_reg(int argc, char **argv)
 {
     int res;
@@ -444,6 +488,9 @@ int cmd_i2c_get_id(int argc, char **argv)
 static const shell_command_t shell_commands[] = {
     { "i2c_acquire", "Get access to the I2C bus", cmd_i2c_acquire },
     { "i2c_release", "Release to the I2C bus", cmd_i2c_release },
+#ifdef MODULE_PERIPH_I2C_RECONFIGURE
+    { "i2c_gpio", "Re-configures I2C pins to GPIO mode and back.", cmd_i2c_gpio },
+#endif
     { "i2c_read_reg", "Read byte from register", cmd_i2c_read_reg },
     { "i2c_read_regs", "Read bytes from registers", cmd_i2c_read_regs },
     { "i2c_read_byte", "Read byte from the I2C device", cmd_i2c_read_byte },