/* esp/gpio_regs.h
 *
 * ESP8266 GPIO register definitions
 *
 * Not compatible with ESP SDK register access code.
 */

#ifndef _ESP_GPIO_REGS_H
#define _ESP_GPIO_REGS_H

#include "esp/types.h"
#include "common_macros.h"

#define GPIO_BASE 0x60000300
#define GPIO (*(struct GPIO_REGS *)(GPIO_BASE))

/** GPIO output registers GPIO.OUT, GPIO.OUT_SET, GPIO.OUT_CLEAR:
 *
 * _SET and _CLEAR write-only registers set and clear bits in the main register,
 * respectively.
 *
 * i.e.
 *   GPIO.OUT_SET = BIT(3);
 * and
 *   GPIO.OUT |= BIT(3);
 *
 * ... are equivalent, but the former uses fewer CPU cycles.
 *
 * ENABLE_OUT / ENABLE_OUT_SET / ENABLE_OUT_CLEAR:
 *
 * Determine whether the corresponding GPIO has its output enabled or not.
 * When clear, GPIO can function as an input.  When set, GPIO will drive its
 * output (and IN register will simply reflect the output state).
 *
 * (_SET/_CLEAR function similarly to OUT registers)
 *
 * STATUS / STATUS_SET / STATUS_CLEAR:
 *
 * Indicates which GPIOs have triggered an interrupt.  Interrupt status should
 * be reset by writing to STATUS or STATUS_CLEAR.
 *
 * (_SET/_CLEAR function similarly to OUT registers)
 *
 * IN:
 *
 * Low 16 bits represent GPIO0-15 state (see also above).
 *
 * High 16 bits represent "strapping pins" values captured at reset time:
 * bit 31 - GPIO10 (SD_DATA3)
 * bit 30 - GPIO9 (SD_DATA2)
 * bit 29 - GPIO7 (SD_DATA0)
 * bit 18 - GPIO15 (MTDO)
 * bit 17 - GPIO0
 * bit 16 - GPIO2
 * (In other words, highest 3 and lowest 3 bits of 16-bit half-word are used).
 * BootROM uses strapping pin values to determine boot mode.
 *
 * Source and more information: 0D-ESP8266__Pin_List*.xlsx document
 */

struct GPIO_REGS {
    uint32_t volatile OUT;              // 0x00
    uint32_t volatile OUT_SET;          // 0x04
    uint32_t volatile OUT_CLEAR;        // 0x08
    uint32_t volatile ENABLE_OUT;       // 0x0c
    uint32_t volatile ENABLE_OUT_SET;   // 0x10
    uint32_t volatile ENABLE_OUT_CLEAR; // 0x14
    uint32_t volatile IN;               // 0x18
    uint32_t volatile STATUS;           // 0x1c
    uint32_t volatile STATUS_SET;       // 0x20
    uint32_t volatile STATUS_CLEAR;     // 0x24
    uint32_t volatile CONF[16];         // 0x28 - 0x64
    uint32_t volatile PWM;              // 0x68
    uint32_t volatile RTC_CALIB;        // 0x6c
    uint32_t volatile RTC_CALIB_RESULT; // 0x70
};

_Static_assert(sizeof(struct GPIO_REGS) == 0x74, "GPIO_REGS is the wrong size");

/* Details for additional OUT register fields */

/* Bottom 16 bits of GPIO.OUT are for GPIOs 0-15, but upper 16 bits
   are used to configure the input signalling pins for Bluetooth
   Coexistence config (see esp/phy.h for a wrapper function).
*/
#define GPIO_OUT_PIN_MASK 0x0000FFFF
#define GPIO_OUT_BT_COEXIST_MASK 0x03FF0000
#define GPIO_OUT_BT_ACTIVE_ENABLE BIT(24)
#define GPIO_OUT_BT_PRIORITY_ENABLE BIT(25)
#define GPIO_OUT_BT_ACTIVE_PIN_M 0x0F
#define GPIO_OUT_BT_ACTIVE_PIN_S 16
#define GPIO_OUT_BT_PRIORITY_PIN_M 0x0F
#define GPIO_OUT_BT_PRIORITY_PIN_S 20

/* Details for CONF[i] registers */

/* GPIO.CONF[i] control the pin behavior for the corresponding GPIO in/output.
 *
 * GPIO_CONF_CONFIG (multi-value)
 *     FIXME: Unclear what these do.  Need to find a better name.
 *
 * GPIO_CONF_WAKEUP_ENABLE (boolean)
 *     Can an interrupt contion on this pin wake the processor from a sleep
 *     state?
 *
 * GPIO_CONF_INTTYPE (multi-value)
 *     Under what conditions this GPIO input should generate an interrupt.
 *     (see gpio_inttype_t enum below for values)
 *
 * GPIO_CONF_OPEN_DRAIN (boolean)
 *     If this bit is set, the pin is in "open drain" mode - a high output state
 *     will leave the pin floating but not source any current. If bit is cleared,
 *     the pin is in push/pull mode so a high output state will drive the pin up
 *     to +Vcc (3.3V).  In either case, a low output state will pull the pin down
 *     to ground.
 *
 *     GPIO_CONF_OPEN_DRAIN does not appear to work on all pins.
 *
 *
 * GPIO_CONF_SOURCE_PWM (boolean)
 *     When set, GPIO pin output will be connected to the sigma-delta PWM
 *     generator (controlled by the GPIO.PWM register).  When cleared, pin
 *     output will function as a normal GPIO output (controlled by the
 *     GPIO.OUT* registers).
 */

#define GPIO_CONF_CONFIG_M       0x00000003
#define GPIO_CONF_CONFIG_S       11
#define GPIO_CONF_WAKEUP_ENABLE  BIT(10)
#define GPIO_CONF_INTTYPE_M      0x00000007
#define GPIO_CONF_INTTYPE_S      7
#define GPIO_CONF_OPEN_DRAIN     BIT(2)
#define GPIO_CONF_SOURCE_PWM     BIT(0)

/* Valid values for the GPIO_CONF_INTTYPE field */
typedef enum {
    GPIO_INTTYPE_NONE       = 0,
    GPIO_INTTYPE_EDGE_POS   = 1,
    GPIO_INTTYPE_EDGE_NEG   = 2,
    GPIO_INTTYPE_EDGE_ANY   = 3,
    GPIO_INTTYPE_LEVEL_LOW  = 4,
    GPIO_INTTYPE_LEVEL_HIGH = 5,
} gpio_inttype_t;

/* Details for PWM register */

#define GPIO_PWM_ENABLE          BIT(16)
#define GPIO_PWM_PRESCALER_M     0x000000ff
#define GPIO_PWM_PRESCALER_S     8
#define GPIO_PWM_TARGET_M        0x000000ff
#define GPIO_PWM_TARGET_S        0

/* Details for RTC_CALIB register */

#define GPIO_RTC_CALIB_START     BIT(31)
#define GPIO_RTC_CALIB_PERIOD_M  0x000003ff
#define GPIO_RTC_CALIB_PERIOD_S  0

/* Details for RTC_CALIB_RESULT register */

#define GPIO_RTC_CALIB_RESULT_READY       BIT(31)
#define GPIO_RTC_CALIB_RESULT_READY_REAL  BIT(30)
#define GPIO_RTC_CALIB_RESULT_VALUE_M     0x000fffff
#define GPIO_RTC_CALIB_RESULT_VALUE_S     0

#endif /* _ESP_GPIO_REGS_H */