Merge pull request #1358 from tannewt/fix_840_qspi

Fix QSPI on Feather nRF52840

Author: dhalbert

ports/nrf/boards/feather_nrf52840_express/mpconfigboard.mk

@@ -20,6 +20,6 @@ endif
 
 NRF_DEFINES += -DNRF52840_XXAA -DNRF52840
 
-SPI_FLASH_FILESYSTEM = 1
+QSPI_FLASH_FILESYSTEM = 1
 EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = "GD25Q16C"

ports/nrf/supervisor/qspi_flash.c

@@ -115,7 +115,7 @@ void spi_flash_init(void) {
             .dpmconfig = false
         },
         .phy_if = {
-            .sck_freq = NRF_QSPI_FREQ_32MDIV16,
+            .sck_freq = NRF_QSPI_FREQ_32MDIV16, // Start at a slow 2mhz and speed up once we know what we're talking to.
             .sck_delay = 10,    // min time CS must stay high before going low again. in unit of 62.5 ns
             .spi_mode = NRF_QSPI_MODE_0,
             .dpmen = false
@@ -132,7 +132,7 @@ void spi_flash_init(void) {
     qspi_cfg.pins.io2_pin = MICROPY_QSPI_DATA2;
     qspi_cfg.pins.io3_pin = MICROPY_QSPI_DATA3;
     qspi_cfg.prot_if.readoc = NRF_QSPI_READOC_READ4IO;
-    qspi_cfg.prot_if.writeoc = NRF_QSPI_WRITEOC_PP4IO;
+    qspi_cfg.prot_if.writeoc = NRF_QSPI_WRITEOC_PP4O;
 #endif
 
     // No callback for blocking API
@@ -142,5 +142,17 @@ void spi_flash_init(void) {
 void spi_flash_init_device(const external_flash_device* device) {
     check_quad_enable(device);
 
-    // TODO(tannewt): Adjust the speed for the found device.
+    // Switch to single output line if the device doesn't support quad programs.
+    if (!device->supports_qspi_writes) {
+        NRF_QSPI->IFCONFIG0 &= ~QSPI_IFCONFIG0_WRITEOC_Msk;
+        NRF_QSPI->IFCONFIG0 |= QSPI_IFCONFIG0_WRITEOC_PP;
+    }
+
+    // Speed up as much as we can.
+    uint8_t sckfreq = 0;
+    while (32000000 / (sckfreq + 1) > device->max_clock_speed_mhz * 1000000 && sckfreq < 16) {
+        sckfreq += 1;
+    }
+    NRF_QSPI->IFCONFIG1 &= ~QSPI_IFCONFIG1_SCKFREQ_Msk;
+    NRF_QSPI->IFCONFIG1 |=  sckfreq << QSPI_IFCONFIG1_SCKDELAY_Pos;
 }

supervisor/shared/external_flash/devices.h

@@ -86,7 +86,7 @@ typedef struct {
 }
 
 // Settings for the Gigadevice GD25Q16C 2MiB SPI flash.
-// Datasheet: http://www.gigadevice.com/wp-content/uploads/2017/12/DS-00086-GD25Q16C-Rev2.6.pdf
+// Datasheet: http://www.gigadevice.com/datasheet/gd25q16c/
 #define GD25Q16C {\
     .total_size = (1 << 21), /* 2 MiB */ \
     .start_up_time_us = 5000, \