pbio/drv/rproc/rproc_ev3: Add I2C interface for PRU1

This defines the communications structure and sets up the resources
for PRU1's software I2C controller.

Author: ArcaneNibble

lib/pbio/drv/i2c/i2c_ev3.c

@@ -18,6 +18,8 @@
 #include <pbdrv/i2c.h>
 #include "i2c_ev3.h"
 
+#include "../rproc/rproc_ev3.h"
+
 #define DEBUG 1
 #if DEBUG
 #include <stdio.h>
@@ -38,10 +40,10 @@ struct _pbdrv_i2c_dev_t {
     //
 };
 
-static pbdrv_i2c_dev_t i2c_devs[PBDRV_CONFIG_I2C_EV3_NUM_DEV];
+static pbdrv_i2c_dev_t i2c_devs[PBDRV_RPROC_EV3_PRU1_NUM_I2C_BUSES];
 
 pbio_error_t pbdrv_i2c_get_instance(uint8_t id, pbdrv_i2c_dev_t **i2c_dev) {
-    if (id >= PBDRV_CONFIG_I2C_EV3_NUM_DEV) {
+    if (id >= PBDRV_RPROC_EV3_PRU1_NUM_I2C_BUSES) {
         return PBIO_ERROR_INVALID_ARG;
     }
     pbdrv_i2c_dev_t *dev = &i2c_devs[id];
@@ -59,7 +61,7 @@ pbio_error_t pbdrv_i2c_placeholder_operation(pbdrv_i2c_dev_t *i2c_dev, const cha
 }
 
 void pbdrv_i2c_init(void) {
-    for (int i = 0; i < PBDRV_CONFIG_I2C_EV3_NUM_DEV; i++) {
+    for (int i = 0; i < PBDRV_RPROC_EV3_PRU1_NUM_I2C_BUSES; i++) {
         const pbdrv_i2c_ev3_platform_data_t *pdata = &pbdrv_i2c_ev3_platform_data[i];
         pbdrv_i2c_dev_t *i2c = &i2c_devs[i];
         i2c->pdata = pdata;

lib/pbio/drv/rproc/rproc_ev3.c

@@ -45,6 +45,12 @@ void pbdrv_rproc_init(void) {
     TimerPeriodSet(SOC_TMR_0_REGS, TMR_TIMER34, 256 * 256 - 1);
     TimerEnable(SOC_TMR_0_REGS, TMR_TIMER34, TMR_ENABLE_CONT);
 
+    // Enable Timer2 "12" half for 20 kHz = 2 * 10 kHz
+    // This is used by the PRU to time I2C bits
+    TimerConfigure(SOC_TMR_2_REGS, TMR_CFG_32BIT_UNCH_CLK_BOTH_INT);
+    TimerPeriodSet(SOC_TMR_2_REGS, TMR_TIMER12, SOC_SYSCLK_2_FREQ / (2 * PBDRV_RPROC_EV3_PRU1_I2C_CLK_SPEED_HZ) - 1);
+    TimerEnable(SOC_TMR_2_REGS, TMR_TIMER12, TMR_ENABLE_CONT);
+
     // Clear shared command memory
     memset((void *)&pbdrv_rproc_ev3_pru1_shared_ram, 0, sizeof(pbdrv_rproc_ev3_pru1_shared_ram));
 

lib/pbio/drv/rproc/rproc_ev3_pru1.h

@@ -11,6 +11,45 @@
 // between the two codebases and must be kept in sync.
 
 #define PBDRV_RPROC_EV3_PRU1_NUM_PWM_CHANNELS   4
+#define PBDRV_RPROC_EV3_PRU1_NUM_I2C_BUSES      4
+
+#define PBDRV_RPROC_EV3_PRU1_I2C_CLK_SPEED_HZ   10000
+
+// I2C command bits, valid when bit7 == 0
+// Start an I2C transaction
+#define PBDRV_RPROC_EV3_PRU1_I2C_CMD_START          (1 << 0)
+// Generate a stop, clock pulse, and start instead of a repeated start
+// Used for the NXT ultrasonic sensor.
+#define PBDRV_RPROC_EV3_PRU1_I2C_CMD_NXT_QUIRK      (1 << 1)
+
+// I2C status bits, valid when bit7 == 1
+// Indicates transaction is complete
+#define PBDRV_RPROC_EV3_PRU1_I2C_STAT_DONE          (1 << 7)
+// Mask for the status code
+#define PBDRV_RPROC_EV3_PRU1_I2C_STAT_MASK          0x7f
+
+// I2C transaction status codes
+enum {
+    PBDRV_RPROC_EV3_PRU1_I2C_STAT_OK,
+    PBDRV_RPROC_EV3_PRU1_I2C_STAT_TIMEOUT,
+    PBDRV_RPROC_EV3_PRU1_I2C_STAT_NAK,
+};
+
+#define PBDRV_RPROC_EV3_PRU1_I2C_PACK_FLAGS(daddr, rlen, wlen, flags)   \
+    ((((daddr) & 0xff) << 24) |                                         \
+    (((rlen) & 0xff) << 16) |                                           \
+    (((wlen) & 0xff) << 8) |                                            \
+    ((flags) & 0xff))
+
+typedef struct {
+    // bit[7:0]     status or flags
+    // bit[15:8]    write length
+    // bit[23:16]   read length
+    // bit[31:24]   device address (unshifted)
+    uint32_t flags;
+    // Physical address of a transaction buffer
+    uintptr_t buffer;
+} pbdrv_rproc_ev3_pru1_i2c_command_t;
 
 typedef struct {
     union {
@@ -25,6 +64,7 @@ typedef struct {
     // of them and route ARM accesses through the PRU.
     uint32_t gpio_bank_01_dir_set;
     uint32_t gpio_bank_01_dir_clr;
+    pbdrv_rproc_ev3_pru1_i2c_command_t i2c[PBDRV_RPROC_EV3_PRU1_NUM_I2C_BUSES];
 } pbdrv_rproc_ev3_pru1_shared_ram_t;
 
 #endif // _INTERNAL_PBDRV_RPROC_EV3_PRU1_H_

lib/pbio/platform/ev3/pbdrvconfig.h

@@ -41,7 +41,6 @@
 
 #define PBDRV_CONFIG_I2C                            (1)
 #define PBDRV_CONFIG_I2C_EV3                        (1)
-#define PBDRV_CONFIG_I2C_EV3_NUM_DEV                (4)
 
 #define PBDRV_CONFIG_BUTTON                         (1)
 #define PBDRV_CONFIG_BUTTON_GPIO                    (1)