nrf: add SPIM3 support

6 files changed, 79 insertions, 30 deletions

diff --git a/locale/circuitpython.pot b/locale/circuitpython.pot
index 3e4413068..1a378e331 100644
--- a/locale/circuitpython.pot
+++ b/locale/circuitpython.pot
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-02-07 10:02-0500\n"
+"POT-Creation-Date: 2020-02-11 19:18-0500\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
diff --git a/ports/nrf/boards/common.template.ld b/ports/nrf/boards/common.template.ld
index 607a1dc93..427b6b35b 100644
--- a/ports/nrf/boards/common.template.ld
+++ b/ports/nrf/boards/common.template.ld
@@ -22,7 +22,9 @@ MEMORY
     /* SoftDevice 6.1.0 with 5 connections and various increases takes just under 64kiB.
     /* To measure the minimum required amount of memory for given configuration, set this number
        high enough to work and then check the mutation of the value done by sd_ble_enable. */
-    RAM (xrw)       : ORIGIN = 0x20000000 + 64K, LENGTH = 256K - 64K
+    SPIM3_RAM (rw)  : ORIGIN = 0x20000000 + 64K, LENGTH = 8K
+    RAM (xrw)       : ORIGIN = 0x20000000 + 64K + 8K, LENGTH = 256K - 64K -8K
+
 }
 
 /* produce a link error if there is not this amount of RAM available */
@@ -37,6 +39,10 @@ _estack = ORIGIN(RAM) + LENGTH(RAM);
 _ram_end = ORIGIN(RAM) + LENGTH(RAM);
 _heap_end = 0x20020000; /* tunable */
 
+/* nrf52840 SPIM3 needs its own area to work around hardware problems. Nothing else may use this space. */
+_spim3_ram = ORIGIN(SPIM3_RAM);
+_spim3_ram_end = ORIGIN(SPIM3_RAM) + LENGTH(RAM);
+
 /* define output sections */
 SECTIONS
 {
diff --git a/ports/nrf/common-hal/busio/SPI.c b/ports/nrf/common-hal/busio/SPI.c
index 8e1d73bf0..fe943a221 100644
--- a/ports/nrf/common-hal/busio/SPI.c
+++ b/ports/nrf/common-hal/busio/SPI.c
@@ -22,6 +22,8 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
+#include <string.h>
+
 #include "shared-bindings/busio/SPI.h"
 #include "py/mperrno.h"
 #include "py/runtime.h"
@@ -29,33 +31,34 @@
 #include "nrfx_spim.h"
 #include "nrf_gpio.h"
 
+// These are in order from ighest available frequency to lowest (32MHz first, then 8MHz).
 STATIC spim_peripheral_t spim_peripherals[] = {
 #if NRFX_CHECK(NRFX_SPIM3_ENABLED)
     // SPIM3 exists only on nRF52840 and supports 32MHz max. All other SPIM's are only 8MHz max.
     // Allocate SPIM3 first.
     { .spim = NRFX_SPIM_INSTANCE(3),
-      .max_frequency_MHz = 32,
+      .max_frequency = 32000000,
       .max_xfer_size = SPIM3_EASYDMA_MAXCNT_SIZE,
     },
 #endif
 #if NRFX_CHECK(NRFX_SPIM2_ENABLED)
     // SPIM2 is not shared with a TWIM, so allocate before the shared ones.
     { .spim = NRFX_SPIM_INSTANCE(2),
-      .max_frequency_MHz = 8,
+      .max_frequency = 8000000,
       .max_xfer_size = SPIM2_EASYDMA_MAXCNT_SIZE,
     },
 #endif
 #if NRFX_CHECK(NRFX_SPIM1_ENABLED)
     // SPIM1 and TWIM1 share an address.
     { .spim = NRFX_SPIM_INSTANCE(1),
-      .max_frequency_MHz = 8,
+      .max_frequency = 8000000,
       .max_xfer_size = SPIM1_EASYDMA_MAXCNT_SIZE,
     },
 #endif
 #if NRFX_CHECK(NRFX_SPIM0_ENABLED)
     // SPIM0 and TWIM0 share an address.
     { .spim = NRFX_SPIM_INSTANCE(0),
-      .max_frequency_MHz = 8,
+      .max_frequency = 8000000,
       .max_xfer_size = SPIM0_EASYDMA_MAXCNT_SIZE,
     },
 #endif
@@ -63,6 +66,11 @@ STATIC spim_peripheral_t spim_peripherals[] = {
 
 STATIC bool never_reset[MP_ARRAY_SIZE(spim_peripherals)];
 
+// Separate RAM area for SPIM3 transmit buffer to avoid SPIM3 hardware errata.
+// https://infocenter.nordicsemi.com/index.jsp?topic=%2Ferrata_nRF52840_Rev2%2FERR%2FnRF52840%2FRev2%2Flatest%2Fanomaly_840_198.html
+extern uint32_t _spim3_ram;
+STATIC uint8_t *spim3_transmit_buffer = (uint8_t *) &_spim3_ram;
+
 void spi_reset(void) {
     for (size_t i = 0 ; i < MP_ARRAY_SIZE(spim_peripherals); i++) {
         if (never_reset[i]) {
@@ -122,7 +130,7 @@ static nrf_spim_frequency_t baudrate_to_spim_frequency(const uint32_t baudrate)
 }
 
 void common_hal_busio_spi_construct(busio_spi_obj_t *self, const mcu_pin_obj_t * clock, const mcu_pin_obj_t * mosi, const mcu_pin_obj_t * miso) {
-    // Find a free instance.
+    // Find a free instance, with most desirable (highest freq and not shared) allocated first.
     self->spim_peripheral = NULL;
     for (size_t i = 0 ; i < MP_ARRAY_SIZE(spim_peripherals); i++) {
         if ((spim_peripherals[i].spim.p_reg->ENABLE & SPIM_ENABLE_ENABLE_Msk) == 0) {
@@ -137,7 +145,8 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self, const mcu_pin_obj_t *
 
     nrfx_spim_config_t config = NRFX_SPIM_DEFAULT_CONFIG(NRFX_SPIM_PIN_NOT_USED, NRFX_SPIM_PIN_NOT_USED,
                                                          NRFX_SPIM_PIN_NOT_USED, NRFX_SPIM_PIN_NOT_USED);
-    config.frequency = NRF_SPIM_FREQ_8M;
+
+    config.frequency = baudrate_to_spim_frequency(self->spim_peripheral->max_frequency);
 
     config.sck_pin = clock->number;
     self->clock_pin_number = clock->number;
@@ -189,8 +198,7 @@ bool common_hal_busio_spi_configure(busio_spi_obj_t *self, uint32_t baudrate, ui
 
     // Set desired frequency, rounding down, and don't go above available frequency for this SPIM.
     nrf_spim_frequency_set(self->spim_peripheral->spim.p_reg,
-                           baudrate_to_spim_frequency(MIN(baudrate,
-                                                          self->spim_peripheral->max_frequency_MHz * 1000000)));
+                           baudrate_to_spim_frequency(MIN(baudrate, self->spim_peripheral->max_frequency)));
 
     nrf_spim_mode_t mode = NRF_SPIM_MODE_0;
     if (polarity) {
@@ -224,21 +232,36 @@ void common_hal_busio_spi_unlock(busio_spi_obj_t *self) {
 }
 
 bool common_hal_busio_spi_write(busio_spi_obj_t *self, const uint8_t *data, size_t len) {
-    if (len == 0)
+    if (len == 0) {
         return true;
+    }
+
+    const bool is_spim3 = self->spim_peripheral->spim.p_reg == NRF_SPIM3;
 
     const uint32_t max_xfer_size = self->spim_peripheral->max_xfer_size;
     const uint32_t parts = len / max_xfer_size;
     const uint32_t remainder = len % max_xfer_size;
 
     for (uint32_t i = 0; i < parts; ++i) {
-        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_XFER_TX(data + i * max_xfer_size, max_xfer_size);
+        uint8_t *start = (uint8_t *) (data + i * max_xfer_size);
+        if (is_spim3) {
+            // If SPIM3, copy into unused RAM block, and do DMA from there.
+            memcpy(spim3_transmit_buffer, start, max_xfer_size);
+            start = spim3_transmit_buffer;
+        }
+        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_XFER_TX(start, max_xfer_size);
         if (nrfx_spim_xfer(&self->spim_peripheral->spim, &xfer, 0) != NRFX_SUCCESS)
             return false;
     }
 
     if (remainder > 0) {
-        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_XFER_TX(data + parts * max_xfer_size, remainder);
+        uint8_t *start = (uint8_t *) (data + parts * max_xfer_size);
+        if (is_spim3) {
+            // If SPIM3, copy into unused RAM block, and do DMA from there.
+            memcpy(spim3_transmit_buffer, start, remainder);
+            start = spim3_transmit_buffer;
+        }
+        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_XFER_TX(start, remainder);
         if (nrfx_spim_xfer(&self->spim_peripheral->spim, &xfer, 0) != NRFX_SUCCESS)
             return false;
     }
@@ -247,8 +270,9 @@ bool common_hal_busio_spi_write(busio_spi_obj_t *self, const uint8_t *data, size
 }
 
 bool common_hal_busio_spi_read(busio_spi_obj_t *self, uint8_t *data, size_t len, uint8_t write_value) {
-    if (len == 0)
+    if (len == 0) {
         return true;
+    }
 
     const uint32_t max_xfer_size = self->spim_peripheral->max_xfer_size;
     const uint32_t parts = len / max_xfer_size;
@@ -270,23 +294,37 @@ bool common_hal_busio_spi_read(busio_spi_obj_t *self, uint8_t *data, size_t len,
 }
 
 bool common_hal_busio_spi_transfer(busio_spi_obj_t *self, uint8_t *data_out, uint8_t *data_in, size_t len) {
-    if (len == 0)
+    if (len == 0) {
         return true;
+    }
 
+    const bool is_spim3 = self->spim_peripheral->spim.p_reg == NRF_SPIM3;
 
     const uint32_t max_xfer_size = self->spim_peripheral->max_xfer_size;
     const uint32_t parts = len / max_xfer_size;
     const uint32_t remainder = len % max_xfer_size;
 
     for (uint32_t i = 0; i < parts; ++i) {
-        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_SINGLE_XFER(data_out + i * max_xfer_size, max_xfer_size,
+        uint8_t *out_start = (uint8_t *) (data_out + i * max_xfer_size);
+        if (is_spim3) {
+            // If SPIM3, copy into unused RAM block, and do DMA from there.
+            memcpy(spim3_transmit_buffer, out_start, max_xfer_size);
+            out_start = spim3_transmit_buffer;
+        }
+        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_SINGLE_XFER(out_start, max_xfer_size,
             data_in + i * max_xfer_size, max_xfer_size);
         if (nrfx_spim_xfer(&self->spim_peripheral->spim, &xfer, 0) != NRFX_SUCCESS)
             return false;
     }
 
     if (remainder > 0) {
-        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_SINGLE_XFER(data_out + parts * max_xfer_size, remainder,
+        uint8_t *out_start = (uint8_t *) (data_out + parts * max_xfer_size);
+        if (is_spim3) {
+            // If SPIM3, copy into unused RAM block, and do DMA from there.
+            memcpy(spim3_transmit_buffer, out_start, remainder);
+            out_start = spim3_transmit_buffer;
+        }
+        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_SINGLE_XFER(out_start, remainder,
             data_in + parts * max_xfer_size, remainder);
         if (nrfx_spim_xfer(&self->spim_peripheral->spim, &xfer, 0) != NRFX_SUCCESS)
             return false;
@@ -325,9 +363,9 @@ uint32_t common_hal_busio_spi_get_frequency(busio_spi_obj_t* self) {
 }
 
 uint8_t common_hal_busio_spi_get_phase(busio_spi_obj_t* self) {
-    return 0;
+    return (self->spim_peripheral->spim.p_reg->CONFIG & SPIM_CONFIG_CPHA_Msk) >> SPIM_CONFIG_CPHA_Pos;
 }
 
 uint8_t common_hal_busio_spi_get_polarity(busio_spi_obj_t* self) {
-    return 0;
+    return (self->spim_peripheral->spim.p_reg->CONFIG & SPIM_CONFIG_CPOL_Msk) >> SPIM_CONFIG_CPOL_Pos;
 }
diff --git a/ports/nrf/common-hal/busio/SPI.h b/ports/nrf/common-hal/busio/SPI.h
index 1b0de8acf..738a1de78 100644
--- a/ports/nrf/common-hal/busio/SPI.h
+++ b/ports/nrf/common-hal/busio/SPI.h
@@ -32,7 +32,7 @@
 
 typedef struct {
     nrfx_spim_t spim;
-    uint8_t max_frequency_MHz;
+    uint32_t max_frequency;
     uint8_t max_xfer_size;
 } spim_peripheral_t;
 
diff --git a/ports/nrf/nrfx_config.h b/ports/nrf/nrfx_config.h
index 82f6514df..e37c60934 100644
--- a/ports/nrf/nrfx_config.h
+++ b/ports/nrf/nrfx_config.h
@@ -26,10 +26,9 @@
 
 // CIRCUITPY_NRF_NUM_I2C is 1 or 2 to choose how many I2C (TWIM) peripherals
 // to provide.
-// This can go away once we have SPIM3 working: then we can have two
-// I2C and two SPI.
+// With SPIM3 working we can have two I2C and two SPI.
 #ifndef CIRCUITPY_NRF_NUM_I2C
-#define CIRCUITPY_NRF_NUM_I2C 1
+#define CIRCUITPY_NRF_NUM_I2C 2
 #endif
 
 #if CIRCUITPY_NRF_NUM_I2C != 1 && CIRCUITPY_NRF_NUM_I2C != 2
@@ -42,13 +41,12 @@
 #define NRFX_SPIM1_ENABLED 1
 #endif
 #define NRFX_SPIM2_ENABLED 1
-// DON'T ENABLE SPIM3 DUE TO ANOMALY WORKAROUND FAILURE (SEE ABOVE).
-// #ifdef NRF52840_XXAA
-//     #define NRFX_SPIM_EXTENDED_ENABLED 1
-//     #define NRFX_SPIM3_ENABLED 1
-// #else
-//     #define NRFX_SPIM3_ENABLED 0
-// #endif
+#ifdef NRF52840_XXAA
+    #define NRFX_SPIM_EXTENDED_ENABLED 1
+    #define NRFX_SPIM3_ENABLED 1
+#else
+    #define NRFX_SPIM3_ENABLED 0
+#endif
 
 
 #define NRFX_SPIM_DEFAULT_CONFIG_IRQ_PRIORITY 7
diff --git a/shared-bindings/busio/SPI.c b/shared-bindings/busio/SPI.c
index d1791bef3..2ae312a35 100644
--- a/shared-bindings/busio/SPI.c
+++ b/shared-bindings/busio/SPI.c
@@ -56,6 +56,13 @@
 //| .. class:: SPI(clock, MOSI=None, MISO=None)
 //|
 //|    Construct an SPI object on the given pins.
+
+//|    ..note:: The SPI peripherals allocated in order of desirability, if possible,
+//|      such as highest speed and not shared use first. For instance, on the nRF52840,
+//|      there is a single 32MHz SPI peripheral, and multiple 8MHz peripherals,
+//|      some of which may also be used for I2C. The 32MHz SPI peripheral is returned
+//|      first, then the exclusive 8MHz SPI peripheral, and finally the shared 8MHz
+//|      peripherals.
 //|
 //|   .. seealso:: Using this class directly requires careful lock management.
 //|       Instead, use :class:`~adafruit_bus_device.spi_device.SPIDevice` to