using SPI with a CS of -1 should be valid

this could possibly fix whitecatboard#384

components/sys/drivers/spi.c

@@ -1,6 +1,6 @@
 /*
- * Copyright (C) 2015 - 2020, IBEROXARXA SERVICIOS INTEGRALES, S.L.
- * Copyright (C) 2015 - 2020, Jaume Olivé Petrus ([email protected])
+ * Copyright (C) 2015 - 2018, IBEROXARXA SERVICIOS INTEGRALES, S.L.
+ * Copyright (C) 2015 - 2018, Jaume Olivé Petrus ([email protected])
  *
  * All rights reserved.
  *
@@ -549,7 +549,7 @@ int spi_ll_setup(uint8_t unit, uint8_t master, int8_t cs, uint8_t mode, uint32_t
     }
 
     // Setup CS
-    if (!(flags & SPI_FLAG_CS_AUTO)) {
+    if (cs >= 0 && !(flags & SPI_FLAG_CS_AUTO)) {
         gpio_pin_output(cs);
         gpio_ll_pin_set(cs);
     }
@@ -704,7 +704,7 @@ void IRAM_ATTR spi_ll_bulk_read(int deviceid, uint32_t nbytes, uint8_t *data) {
 }
 
 int IRAM_ATTR spi_ll_bulk_rw(int deviceid, uint32_t nbytes, uint8_t *data) {
-    uint8_t *read = (uint8_t *) malloc(nbytes + 3);
+    uint8_t *read = (uint8_t *) malloc(nbytes);
     if (read) {
         spi_master_op(deviceid, 1, nbytes, data, read);
 
@@ -773,7 +773,7 @@ void IRAM_ATTR spi_ll_select(int deviceid) {
     spi_bus[spi_idx(unit)].last_device = deviceid;
     spi_bus[spi_idx(unit)].selected_device = deviceid;
 
-    if (!(spi_bus[spi_idx(unit)].device[device].flags & SPI_FLAG_CS_AUTO)) {
+    if (spi_bus[spi_idx(unit)].device[device].cs >= 0 && !(spi_bus[spi_idx(unit)].device[device].flags & SPI_FLAG_CS_AUTO)) {
         // Select device
         gpio_ll_pin_clr(spi_bus[spi_idx(unit)].device[device].cs);
     }
@@ -783,7 +783,7 @@ void IRAM_ATTR spi_ll_deselect(int deviceid) {
     int unit = (deviceid & 0xff00) >> 8;
     int device = (deviceid & 0x00ff);
 
-    if (!(spi_bus[spi_idx(unit)].device[device].flags & SPI_FLAG_CS_AUTO)) {
+    if (spi_bus[spi_idx(unit)].device[device].cs >= 0 && !(spi_bus[spi_idx(unit)].device[device].flags & SPI_FLAG_CS_AUTO)) {
         // Deselect device
         gpio_ll_pin_set(spi_bus[spi_idx(unit)].device[device].cs);
     }
@@ -900,12 +900,14 @@ driver_error_t *spi_setup(uint8_t unit, uint8_t master, int8_t cs, uint8_t mode,
             cs = CONFIG_LUA_RTOS_SPI3_CS;
         }
 
+        /* -1 is a valid configuration which signifies that CS should not be used
         if (cs == -1) {
             return driver_error(SPI_DRIVER, SPI_ERR_PIN_NOT_ALLOWED, "default cs is not set in kconfig");
         }
+        */
     }
 
-    if (!(GPIO_ALL_OUT & (GPIO_BIT_MASK << cs))) {
+    if (cs >= 0 && !(GPIO_ALL_OUT & (GPIO_BIT_MASK << cs))) {
         return driver_error(SPI_DRIVER, SPI_ERR_PIN_NOT_ALLOWED, "cs, selected pin is not valid for output");
     }
 
@@ -922,7 +924,7 @@ driver_error_t *spi_setup(uint8_t unit, uint8_t master, int8_t cs, uint8_t mode,
     }
 
     driver_unit_lock_error_t *lock_error = NULL;
-    if ((lock_error = driver_lock(SPI_DRIVER, unit, GPIO_DRIVER, cs, flags, "CS"))) {
+    if (cs >= 0 && (lock_error = driver_lock(SPI_DRIVER, unit, GPIO_DRIVER, cs, flags, "CS"))) {
         return driver_lock_error(SPI_DRIVER, lock_error);
     }
 #endif