On Wed, 2018-03-21 at 18:35 +0100, Paolo Pisati wrote:

This patch adds support to the FPGA manager for programming
MachXO2 device’s internal flash memory, via slave SPI.

style trivia:

[]

+static int get_status(struct spi_device *spi, unsigned long *status)
+{
+	struct spi_message msg;
+	struct spi_transfer rx, tx;
+	u8 cmd[] = LSC_READ_STATUS;

static const u8 cmd[]
here and everywhere else as all the tx_buf assignments 
of cmd are to const void *

+	int ret;
+
+	memset(&rx, 0, sizeof(rx));
+	memset(&tx, 0, sizeof(tx));
+	tx.tx_buf = cmd;

[]

+#ifdef DEBUG
+static void dump_status_reg(unsigned long *status)
+{

Instead of multiple declarations of dump_status_reg
it's frequently nicer to use a style like

static void debug_func(args...)
{
#ifdef DEBUG
	[code...]
#endif
}

so if function arguments ever need to be changed
it's only required to be changed in one spot and
not multiply compilation tested with and without
the DEBUG definition

+	char *ferr;
+
+	switch (get_err(status)) {
+	case ENOERR:
+		ferr = "No Error";
+		break;
+	case EID:
+		ferr = "ID ERR";
+		break;
+	case ECMD:
+		ferr = "CMD ERR";
+		break;
+	case ECRC:
+		ferr = "CRC ERR";
+		break;
+	case EPREAM:
+		ferr = "Preamble ERR";
+		break;
+	case EABRT:
+		ferr = "Abort ERR";
+		break;
+	case EOVERFL:
+		ferr = "Overflow ERR";
+		break;
+	case ESDMEOF:
+		ferr = "SDM EOF";
+		break;
+	default:
+		ferr = "Default switch case";
+	}

It's frequently nicer to use a static function
for these enum -> string conversions like:

static const char *get_err_string(unsigned long err)
{
	switch (err) {
	case ENOERR:	return "No Error";
	case EID:	return "ID ERR";
	case ECMD:	return "CMD ERR";
	[...]
	}
	return "default switch case";
}

+	pr_debug("machxo2 status: 0x%08lX - done=%d, cfgena=%d, busy=%d, fail=%d, devver=%d, err=%s\n",
+	       *status, test_bit(DONE, status), test_bit(ENAB, status),
+	       test_bit(BUSY, status), test_bit(FAIL, status),
+		   test_bit(DVER, status), ferr);

So instead of ferr, this could use
	get_err_string(*status)

And please try to keep a consistent alignment for
indentation of multiple line statements

+}
+#else
+static void dump_status_reg(unsigned long *status) {}
+#endif
+
+static int wait_until_not_busy(struct spi_device *spi)
+{
+	unsigned long status;
+	int ret, loop = 0;
+
+	do {
+		ret = get_status(spi, &status);
+		if (ret)
+			break;
+		if (++loop >= MACHXO2_MAX_BUSY_LOOP) {
+			ret = -EBUSY;
+			break;
+		}
+	} while (test_bit(BUSY, &status));
+
+	return ret;
+}

Direct returns are OK and would shorten the function
line count.