[PATCH 1/2] GPIO Driver
Ketul Shah
ketulshah1993 at gmail.com
Tue Jun 30 09:46:37 UTC 2015
diff --git a/cpukit/include/rtems/gpio.h b/cpukit/include/rtems/gpio.h
new file mode 100644
index 0000000..3d68c39
--- /dev/null
+++ b/cpukit/include/rtems/gpio.h
@@ -0,0 +1,64 @@
+/**
+ * @file rtems/gpio.h
+ *
+ * @brief Global GPIO definitions.
+ *
+ * This include the generalized definitions for GPIO
+ */
+
+/**
+ * Copyright (c) 2015 Ketul Shah <ketulshah1993 at gmail.com>
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.org/license/LICENSE.
+ */
+
+#ifndef _RTEMS_GPIO_H
+#define _RTEMS_GPIO_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+/* Returned Error Codes by function */
+#define GPIO_SUCCESSFUL 0 /* operation is OK */
+#define GPIO_UNKNOWN_PIN 1 /* pin not known by bsp */
+#define GPIO_UNCONFIGURED_PIN 2 /* pin unable to configure */
+#define GPIO_MISCONFIGURED_PIN 3 /* pin configuration can't match operation */
+
+/* Possible GPIO Pin States */
+#define GPIO_PIN_STATE_UNCONFIGURED 0
+#define GPIO_PIN_STATE_DIGITAL_OUT 1
+#define GPIO_PIN_STATE_DIGITAL_IN 2
+
+/**
+ * @brief Structure contains all the required members for GPIO access.
+ */
+typedef struct
+{
+ int pin_number;/* The pin number. */
+ void* platform; /* Opaque hardware specific set up details. */
+} gpio_pin_handle;
+
+/**
+ * @brief Initializes the GPIO API.
+ */
+extern void rtems_gpio_initialize(void);
+/**
+ * @brief Selects a GPIO pin for a digital output.
+ */
+extern int rtems_gpio_configure_pin_digital_out(
+ gpio_pin_handle *, unsigned int );
+/**
+ * @brief Turns on the given pin.
+ */
+extern int rtems_gpio_digital_set(gpio_pin_handle *);
+/**
+ * @brief Turns off the given pin.
+ */
+extern int rtems_gpio_digital_clear(gpio_pin_handle *);
+/**
+ * @brief currently configured pin is released and made UNCONFIGURED.
+ */
+extern int rtems_gpio_release_pin(gpio_pin_handle *);
\ No newline at end of file
diff --git a/c/src/lib/libbsp/arm/beagle/gpio/gpio.c b/c/src/lib/libbsp/arm/beagle/gpio/gpio.c
new file mode 100644
index 0000000..541d456
--- /dev/null
+++ b/c/src/lib/libbsp/arm/beagle/gpio/gpio.c
@@ -0,0 +1,210 @@
+/**
+ * @file
+ *
+ * @ingroup arm_beagle
+ *
+ * @brief Global BSP definitions.
+ */
+
+/**
+ * Copyright (c) 2015 Ketul Shah <ketulshah1993 at gmail.com>
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.org/license/LICENSE.
+ */
+
+#include <libcpu/am335x.h>
+#include <rtems.h>
+#include <rtems/gpio.h>
+#include <bsp/irq.h>
+#include <bsp/beagleboneblack.h>
+#include <bsp.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <assert.h>
+
+/**
+ * @brief GPIO API mutex atributes.
+ */
+#define MUTEX_ATRIBUTES \
+ ( RTEMS_LOCAL \
+ | RTEMS_PRIORITY \
+ | RTEMS_BINARY_SEMAPHORE \
+ | RTEMS_INHERIT_PRIORITY \
+ | RTEMS_NO_PRIORITY_CEILING \
+ )
+
+#define OBTAIN_LOCK(s) if(rtems_semaphore_obtain(s, \
+ RTEMS_WAIT, \
+ RTEMS_NO_TIMEOUT \
+ ) != RTEMS_SUCCESSFUL) \
+ printf("Semaphore not obtained\n");
+
+#define RELEASE_LOCK(s) if(rtems_semaphore_release(s) != RTEMS_SUCCESSFUL) \
+ printf("Semaphore not released\n");
+
+/* GPIO bank pin number as per TRM of AM335X */
+static unsigned int gpio_bank_pin[GPIO_PIN_COUNT];
+/* GPIO bank determines register of AM335X */
+static unsigned int gpio_bank[GPIO_PIN_COUNT];
+/* Pin states for all GPIO pins*/
+static unsigned int gpio_pin_state[GPIO_PIN_COUNT];
+/* Variable for gpio initialization */
+static bool is_initialized = false;
+/* Total number of gpio banks */
+static int gpio_bank_count = GPIO_PIN_COUNT / GPIO_PINS_PER_BANK;
+/* Semaphore for avoiding race condition */
+static rtems_id bank_lock;
+
+static const uint32_t gpio_bank_addrs[] =
+ { AM335X_GPIO0, AM335X_GPIO1, AM335X_GPIO2, AM335X_GPIO3 };
+
+static uint32_t inline get_pin_mask(unsigned int pin_number)
+{
+ return (1UL << gpio_bank_pin[pin_number]);
+}
+
+static void inline reg_update_set(unsigned int pin_number,uint32_t reg)
+{
+ uint32_t gpioreg=gpio_bank[pin_number]+reg;
+ uint32_t gpioreg_val=mmio_read(gpioreg);
+ gpioreg_val |= get_pin_mask(pin_number);
+ mmio_write(gpioreg, gpioreg_val);
+}
+
+static void inline reg_update_unset(unsigned int pin_number,uint32_t reg)
+{
+ uint32_t gpioreg=gpio_bank[pin_number]+reg;
+ uint32_t gpioreg_val=mmio_read(gpioreg);
+ gpioreg_val &= ~get_pin_mask(pin_number);
+ mmio_write(gpioreg, gpioreg_val);
+}
+
+/**
+ * @brief Initializes the GPIO API.
+ * Allocates space to gpio_pin_state and sets pin state as UNCONFIGURED.
+ * Creates Semaphore for avoiding any race condition.
+ * If the API has already been initialized silently exits.
+ */
+void rtems_gpio_initialize(void)
+{
+ int i;
+ rtems_status_code status;
+ if ( is_initialized )
+ return;
+
+ is_initialized = true;
+ for ( i = 0; i < GPIO_PIN_COUNT; ++i ) {
+ gpio_pin_state[i] = GPIO_PIN_STATE_UNCONFIGURED;
+ }
+ /* Create GPIO bank Semaphores */
+ status = rtems_semaphore_create(
+ rtems_build_name('G', 'L', 'C', 'K'),
+ 1,
+ MUTEX_ATRIBUTES,
+ 0,
+ &bank_lock
+ );
+ if (status != RTEMS_SUCCESSFUL){
+ printf("Semaphore not created\n");
+ }
+}
+
+/**
+ * @brief Configures a GPIO pin to perform a digital output.
+ *
+ * @retval GPIO_SUCCESSFUL Pin was configured successfully as output.
+ * @retval GPIO_UNKNOWN_PIN Pin is invalid or unknown.
+ * @retval GPIO_MISCONFIGURED_PIN Pin is already configured for another state.
+ */
+int rtems_gpio_configure_pin_digital_out(
+ gpio_pin_handle *gpio_pin_assign,unsigned int pin_number){
+
+ OBTAIN_LOCK(bank_lock);
+ if (pin_number >= GPIO_PIN_COUNT || pin_number < 0){
+ RELEASE_LOCK(bank_lock);
+ return GPIO_UNKNOWN_PIN;
+ }
+ if (
+ gpio_pin_state[gpio_pin_assign->pin_number] != GPIO_PIN_STATE_UNCONFIGURED &&
+ gpio_pin_state[gpio_pin_assign->pin_number] != GPIO_PIN_STATE_DIGITAL_OUT){
+ RELEASE_LOCK(bank_lock);
+ return GPIO_MISCONFIGURED_PIN;
+ }
+
+ gpio_pin_state[gpio_pin_assign->pin_number] = GPIO_PIN_STATE_DIGITAL_OUT;
+ gpio_pin_assign->pin_number = pin_number;
+ gpio_bank_pin[pin_number] = pin_number % GPIO_PINS_PER_BANK;
+ gpio_bank[pin_number] = gpio_bank_addrs[pin_number/GPIO_PINS_PER_BANK];
+
+ reg_update_unset(gpio_pin_assign->pin_number,AM335X_GPIO_OE);
+
+ RELEASE_LOCK(bank_lock);
+ return GPIO_SUCCESSFUL;
+}
+
+/**
+ * @brief Gives an output GPIO pin the logical value of 1.
+ * @retval GPIO_SUCCESSFUL Pin was set successfully.
+ * @retval GPIO_MISCONFIGURED_PIN The received pin is not configured
+ * for digital output.
+ */
+int rtems_gpio_digital_set(gpio_pin_handle *gpio_pin_assign){
+
+ OBTAIN_LOCK(bank_lock);
+ if (
+ gpio_pin_state[gpio_pin_assign->pin_number] != GPIO_PIN_STATE_DIGITAL_OUT){
+ RELEASE_LOCK(bank_lock);
+ return GPIO_MISCONFIGURED_PIN;
+ }
+
+ reg_update_set(gpio_pin_assign->pin_number,AM335X_GPIO_DATAOUT);
+
+ RELEASE_LOCK(bank_lock);
+ return GPIO_SUCCESSFUL;
+}
+
+/**
+ * @brief Gives an output GPIO pin the logical value of 0.
+ * @retval GPIO_SUCCESSFUL Pin was cleared successfully.
+ * @retval GPIO_MISCONFIGURED_PIN The received pin is not configured
+ * for digital output.
+ */
+int rtems_gpio_digital_clear(gpio_pin_handle *gpio_pin_assign){
+
+ OBTAIN_LOCK(bank_lock);
+ if (
+ gpio_pin_state[gpio_pin_assign->pin_number] == GPIO_PIN_STATE_DIGITAL_OUT){
+ RELEASE_LOCK(bank_lock);
+ return GPIO_MISCONFIGURED_PIN ;
+ }
+
+ reg_update_unset(gpio_pin_assign->pin_number,AM335X_GPIO_DATAOUT);
+
+ RELEASE_LOCK(bank_lock);
+ return GPIO_SUCCESSFUL;
+}
+/**
+ * @brief Releases currently configured pin and makes unused for repurposing.
+ * @retval GPIO_SUCCESSFUL Pin was released successfully or it is already
+ * UNCONFIGURED state.
+ *
+ */
+int rtems_gpio_release_pin(gpio_pin_handle *gpio_pin_assign){
+
+ OBTAIN_LOCK(bank_lock);
+ if (
+ gpio_pin_state[gpio_pin_assign->pin_number] == GPIO_PIN_STATE_UNCONFIGURED){
+ RELEASE_LOCK(bank_lock);
+ return GPIO_SUCCESSFUL;
+ }
+
+ OBTAIN_LOCK(bank_lock);
+
+ gpio_pin_state[gpio_pin_assign->pin_number] = GPIO_PIN_STATE_UNCONFIGURED;
+ reg_update_set(gpio_pin_assign->pin_number,AM335X_GPIO_OE);
+
+ RELEASE_LOCK(bank_lock);
+ return GPIO_SUCCESSFUL;
+}
\ No newline at end of file
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