nrf: Add I2C timeout parameter and fix disable on error.

Accept the timeout kwarg (default 50ms) for compatibility with
rp2 and alif ports. Also fix TWI peripheral not being disabled
on the transfer error path.

Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>

Author: pi-anl

ports/nrf/modules/machine/i2c.c

@@ -55,11 +55,20 @@
 
 #define nrfx_twi_xfer_desc_t nrfx_twim_xfer_desc_t
 
+#define nrfx_twi_evt_handler_t nrfx_twim_evt_handler_t
+#define nrfx_twi_evt_t         nrfx_twim_evt_t
+#define nrfx_twi_evt_type_t    nrfx_twim_evt_type_t
+
 #define NRFX_TWI_XFER_DESC_RX NRFX_TWIM_XFER_DESC_RX
 #define NRFX_TWI_XFER_DESC_TX NRFX_TWIM_XFER_DESC_TX
 
 #define NRFX_TWI_INSTANCE NRFX_TWIM_INSTANCE
 
+#define NRFX_TWI_EVT_DONE         NRFX_TWIM_EVT_DONE
+#define NRFX_TWI_EVT_ADDRESS_NACK NRFX_TWIM_EVT_ADDRESS_NACK
+#define NRFX_TWI_EVT_DATA_NACK    NRFX_TWIM_EVT_DATA_NACK
+#define NRFX_TWI_EVT_BUS_ERROR    NRFX_TWIM_EVT_BUS_ERROR
+
 #define NRF_TWI_FREQ_100K NRF_TWIM_FREQ_100K
 #define NRF_TWI_FREQ_250K NRF_TWIM_FREQ_250K
 #define NRF_TWI_FREQ_400K NRF_TWIM_FREQ_400K
@@ -69,16 +78,25 @@
 typedef struct _machine_hard_i2c_obj_t {
     mp_obj_base_t base;
     nrfx_twi_t p_twi;     // Driver instance
+    uint32_t timeout;
+    volatile bool xfer_done;
+    volatile nrfx_twi_evt_type_t xfer_evt;
 } machine_hard_i2c_obj_t;
 
-static const machine_hard_i2c_obj_t machine_hard_i2c_obj[] = {
+static machine_hard_i2c_obj_t machine_hard_i2c_obj[] = {
     {{&machine_i2c_type}, .p_twi = NRFX_TWI_INSTANCE(0)},
     {{&machine_i2c_type}, .p_twi = NRFX_TWI_INSTANCE(1)},
 };
 
 void i2c_init0(void) {
 }
 
+static void twi_event_handler(nrfx_twi_evt_t const *p_event, void *p_context) {
+    machine_hard_i2c_obj_t *self = (machine_hard_i2c_obj_t *)p_context;
+    self->xfer_evt = p_event->type;
+    self->xfer_done = true;
+}
+
 static int i2c_find(mp_obj_t id) {
     // given an integer id
     int i2c_id = mp_obj_get_int(id);
@@ -90,7 +108,7 @@ static int i2c_find(mp_obj_t id) {
 
 static void machine_hard_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
     machine_hard_i2c_obj_t *self = self_in;
-    mp_printf(print, "I2C(%u)", self->p_twi.drv_inst_idx);
+    mp_printf(print, "I2C(%u, timeout=%u)", self->p_twi.drv_inst_idx, self->timeout);
 }
 
 /******************************************************************************/
@@ -99,12 +117,13 @@ static void machine_hard_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp
 mp_obj_t machine_hard_i2c_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
     MP_MACHINE_I2C_CHECK_FOR_LEGACY_SOFTI2C_CONSTRUCTION(n_args, n_kw, all_args);
 
-    enum { ARG_id, ARG_scl, ARG_sda, ARG_freq };
+    enum { ARG_id, ARG_scl, ARG_sda, ARG_freq, ARG_timeout };
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_id,       MP_ARG_REQUIRED | MP_ARG_OBJ },
         { MP_QSTR_scl,      MP_ARG_REQUIRED | MP_ARG_OBJ },
         { MP_QSTR_sda,      MP_ARG_REQUIRED | MP_ARG_OBJ },
         { MP_QSTR_freq,     MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_timeout,  MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 50000} },
     };
 
     // parse args
@@ -113,7 +132,9 @@ mp_obj_t machine_hard_i2c_make_new(const mp_obj_type_t *type, size_t n_args, siz
 
     // get static peripheral object
     int i2c_id = i2c_find(args[ARG_id].u_obj);
-    const machine_hard_i2c_obj_t *self = &machine_hard_i2c_obj[i2c_id];
+    machine_hard_i2c_obj_t *self = &machine_hard_i2c_obj[i2c_id];
+
+    self->timeout = args[ARG_timeout].u_int;
 
     nrfx_twi_config_t config;
     #if NRFX_TWI_ENABLED
@@ -139,8 +160,8 @@ mp_obj_t machine_hard_i2c_make_new(const mp_obj_type_t *type, size_t n_args, siz
     // First reset the TWI
     nrfx_twi_uninit(&self->p_twi);
 
-    // Set context to this object.
-    nrfx_twi_init(&self->p_twi, &config, NULL, (void *)self);
+    // Set context to this object, use non-blocking mode with event handler.
+    nrfx_twi_init(&self->p_twi, &config, twi_event_handler, (void *)self);
 
     return MP_OBJ_FROM_PTR(self);
 }
@@ -150,6 +171,9 @@ int machine_hard_i2c_transfer_single(mp_obj_base_t *self_in, uint16_t addr, size
 
     nrfx_twi_enable(&self->p_twi);
 
+    self->xfer_done = false;
+    self->xfer_evt = NRFX_TWI_EVT_DONE;
+
     nrfx_err_t err_code;
     int transfer_ret = 0;
     if (flags & MP_MACHINE_I2C_FLAG_READ) {
@@ -162,6 +186,7 @@ int machine_hard_i2c_transfer_single(mp_obj_base_t *self_in, uint16_t addr, size
     }
 
     if (err_code != NRFX_SUCCESS) {
+        nrfx_twi_disable(&self->p_twi);
         if (err_code == NRFX_ERROR_DRV_TWI_ERR_ANACK) {
             return -MP_ENODEV;
         } else if (err_code == NRFX_ERROR_DRV_TWI_ERR_DNACK) {
@@ -170,8 +195,27 @@ int machine_hard_i2c_transfer_single(mp_obj_base_t *self_in, uint16_t addr, size
         return -MP_ETIMEDOUT;
     }
 
+    // Poll for transfer completion with timeout.
+    mp_uint_t start = mp_hal_ticks_us();
+    while (!self->xfer_done) {
+        if (self->timeout > 0 && (mp_hal_ticks_us() - start) >= self->timeout) {
+            nrfx_twi_disable(&self->p_twi);
+            nrfx_twi_enable(&self->p_twi);
+            return -MP_ETIMEDOUT;
+        }
+        MICROPY_EVENT_POLL_HOOK;
+    }
+
     nrfx_twi_disable(&self->p_twi);
 
+    if (self->xfer_evt == NRFX_TWI_EVT_ADDRESS_NACK) {
+        return -MP_ENODEV;
+    } else if (self->xfer_evt == NRFX_TWI_EVT_DATA_NACK) {
+        return -MP_EIO;
+    } else if (self->xfer_evt != NRFX_TWI_EVT_DONE) {
+        return -MP_EIO;
+    }
+
     return transfer_ret;
 }