extmod/machine_spi: Support firstbit=LSB for machine.SoftSPI.

Being able to send data out in LSB format can be useful, and having support
in the low-level driver is much better than requiring Python code to
reorder the bits before sending them / after receiving them.  In particular
if the hardware does not support the LSB format (eg RP2040) then one needs
to use the SoftSPI in LSB mode.

For this change a default definition of `MICROPY_PY_MACHINE_SPI_MSB/_LSB`
was added to `py/mpconfig.h`, making them available to all ports.  The
identical defines in `esp32/mpconfigport.h` were deleted.

Resolves issues #5340, #11404.

Signed-off-by: robert-hh <robert@hammelrath.com>

1 files changed, 8 insertions, 12 deletions

diff --git a/extmod/machine_spi.c b/extmod/machine_spi.c
index a1d18c9052..5be30e9476 100644
--- a/extmod/machine_spi.c
+++ b/extmod/machine_spi.c
@@ -33,12 +33,6 @@
 
 #include "extmod/modmachine.h"
 
-// if a port didn't define MSB/LSB constants then provide them
-#ifndef MICROPY_PY_MACHINE_SPI_MSB
-#define MICROPY_PY_MACHINE_SPI_MSB (0)
-#define MICROPY_PY_MACHINE_SPI_LSB (1)
-#endif
-
 /******************************************************************************/
 // MicroPython bindings for generic machine.SPI
 
@@ -154,9 +148,9 @@ static uint32_t baudrate_to_delay_half(uint32_t baudrate) {
 
 static void mp_machine_soft_spi_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
     mp_machine_soft_spi_obj_t *self = MP_OBJ_TO_PTR(self_in);
-    mp_printf(print, "SoftSPI(baudrate=%u, polarity=%u, phase=%u,"
+    mp_printf(print, "SoftSPI(baudrate=%u, polarity=%u, phase=%u, firstbit=%u,"
         " sck=" MP_HAL_PIN_FMT ", mosi=" MP_HAL_PIN_FMT ", miso=" MP_HAL_PIN_FMT ")",
-        baudrate_from_delay_half(self->spi.delay_half), self->spi.polarity, self->spi.phase,
+        baudrate_from_delay_half(self->spi.delay_half), self->spi.polarity, self->spi.phase, self->spi.firstbit,
         mp_hal_pin_name(self->spi.sck), mp_hal_pin_name(self->spi.mosi), mp_hal_pin_name(self->spi.miso));
 }
 
@@ -185,9 +179,7 @@ static mp_obj_t mp_machine_soft_spi_make_new(const mp_obj_type_t *type, size_t n
     if (args[ARG_bits].u_int != 8) {
         mp_raise_ValueError(MP_ERROR_TEXT("bits must be 8"));
     }
-    if (args[ARG_firstbit].u_int != MICROPY_PY_MACHINE_SPI_MSB) {
-        mp_raise_ValueError(MP_ERROR_TEXT("firstbit must be MSB"));
-    }
+    self->spi.firstbit = args[ARG_firstbit].u_int;
     if (args[ARG_sck].u_obj == MP_OBJ_NULL
         || args[ARG_mosi].u_obj == MP_OBJ_NULL
         || args[ARG_miso].u_obj == MP_OBJ_NULL) {
@@ -206,11 +198,12 @@ static mp_obj_t mp_machine_soft_spi_make_new(const mp_obj_type_t *type, size_t n
 static void mp_machine_soft_spi_init(mp_obj_base_t *self_in, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     mp_machine_soft_spi_obj_t *self = (mp_machine_soft_spi_obj_t *)self_in;
 
-    enum { ARG_baudrate, ARG_polarity, ARG_phase, ARG_sck, ARG_mosi, ARG_miso };
+    enum { ARG_baudrate, ARG_polarity, ARG_phase, ARG_firstbit, ARG_sck, ARG_mosi, ARG_miso };
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_baudrate, MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_polarity, MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_phase, MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_firstbit, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_sck, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
         { MP_QSTR_mosi, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
         { MP_QSTR_miso, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
@@ -227,6 +220,9 @@ static void mp_machine_soft_spi_init(mp_obj_base_t *self_in, size_t n_args, cons
     if (args[ARG_phase].u_int != -1) {
         self->spi.phase = args[ARG_phase].u_int;
     }
+    if (args[ARG_firstbit].u_int != -1) {
+        self->spi.firstbit = args[ARG_firstbit].u_int;
+    }
     if (args[ARG_sck].u_obj != MP_OBJ_NULL) {
         self->spi.sck = mp_hal_get_pin_obj(args[ARG_sck].u_obj);
     }