flash: spi: perform both flash_read() and flash_write() in chunks of 32 bytes

source/drivers/spi_flash.c

@@ -94,34 +94,57 @@ static size_t spi_flash_get_size(struct flash_dev *dev)
 static size_t spi_flash_read(struct flash_dev *dev, uint32_t addr, void *data,
 	size_t len)
 {
-	char cmd[4] = { SPI_FLASH_READ };
+	char cmd[4];
 	struct spi_dev *spi_dev = dev->priv;
+	size_t nbytes, ret = 0;
 
-	spi_flash_addr(cmd, addr);
+	while (len) {
+		cmd[0] = SPI_FLASH_READ;
+		spi_flash_addr(cmd, addr);
 
-	spi_tx_rx(spi_dev, data, len, cmd, sizeof cmd);
+		nbytes = min(len, 32);
 
-	return len;
+		spi_tx_rx(spi_dev, data, len, cmd, sizeof cmd);
+
+		addr += nbytes;
+		data += nbytes;
+		len -= nbytes;
+		ret += nbytes;
+	}
+
+	return ret;
 }
 
 static size_t spi_flash_write(struct flash_dev *dev, uint32_t addr,
 	const void *data, size_t len)
 {
-	char cmd[4 + len];
+	char cmd[4 + 32];
 	struct spi_dev *spi_dev = dev->priv;
+	size_t nbytes, ret = 0;
 
 	spi_flash_write_enable(dev);
 
-	cmd[0] = SPI_FLASH_PAGE_PROGRAM;
-	spi_flash_addr(cmd, addr);
-	memcpy(cmd + 4, data, len);
+	while (len) {
+		spi_flash_wait(dev);
 
-	spi_tx_rx(spi_dev, NULL, 0, cmd, sizeof cmd);
-	spi_flash_wait(dev);
+		cmd[0] = SPI_FLASH_PAGE_PROGRAM;
+		spi_flash_addr(cmd, addr);
 
+		nbytes = min(len, 32);
+
+		memmove(cmd + 4, data, nbytes);
+		spi_tx_rx(spi_dev, NULL, 0, cmd, sizeof cmd);
+
+		addr += nbytes;
+		data += nbytes;
+		len -= nbytes;
+		ret += nbytes;
+	}
+
+	spi_flash_wait(dev);
 	spi_flash_write_disable(dev);
 
-	return len;
+	return ret;
 }
 
 static int spi_flash_erase(struct flash_dev *dev, uint32_t addr)