spi: Get rid of max_transfer_size parameter in spi_slave structure

max_transfer_size is a property of the SPI controller and not of the spi
slave. Also, this is used only on one SoC currently. There is no need to
handle this at the spi flash layer.

This change moves the handling of max_transfer_size to SoC SPI driver
and gets rid of the max_transfer_size parameter.

BUG=None
BRANCH=None
TEST=Compiles successfully.

Change-Id: I19a1d0a83395a58c2bc1614b24518a3220945a60
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/17463
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins)

src/drivers/spi/spi_flash.c

@@ -123,25 +123,8 @@ static int spi_flash_cmd_read_array(struct spi_slave *spi, u8 *cmd,
 				    size_t cmd_len, u32 offset,
 				    size_t len, void *data)
 {
-	while (len) {
+	spi_flash_addr(offset, cmd);
-		size_t transfer_size;
+	return spi_flash_cmd_read(spi, cmd, cmd_len, data, len);
-
-		if (spi->max_transfer_size)
-			transfer_size = min(len, spi->max_transfer_size);
-		else
-			transfer_size = len;
-
-		spi_flash_addr(offset, cmd);
-
-		if (spi_flash_cmd_read(spi, cmd, cmd_len, data, transfer_size))
-			break;
-
-		offset += transfer_size;
-		data = (void *)((uintptr_t)data + transfer_size);
-		len -= transfer_size;
-	}
-
-	return len != 0;
 }
 
 int spi_flash_cmd_read_fast(const struct spi_flash *flash, u32 offset,

src/include/spi-generic.h

@@ -31,15 +31,10 @@
  *
  *   bus:	ID of the bus that the slave is attached to.
  *   cs:	ID of the chip select connected to the slave.
- *   max_transfer_size: maximum amount of bytes which can be sent in a single
- *              read or write transaction, usually this is a controller
- *              property, kept in the slave structure for convenience. Zero in
- *              this field means 'unlimited'.
  */
 struct spi_slave {
 	unsigned int	bus;
 	unsigned int	cs;
-	unsigned int	max_transfer_size;
 	int force_programmer_specific;
 	struct spi_flash * (*programmer_specific_probe) (struct spi_slave *spi);
 };

src/soc/imgtec/pistachio/spi.c

@@ -445,7 +445,6 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs)
 	img_slave->base = base;
 	slave->bus = bus;
 	slave->cs = cs;
-	slave->max_transfer_size = IMGTEC_SPI_MAX_TRANSFER_SIZE;
 
 	device_parameters->bitrate = 64;
 	device_parameters->cs_setup = 0;
@@ -509,22 +508,12 @@ void spi_release_bus(struct spi_slave *slave)
 }
 
 /* SPI transfer */
-int spi_xfer(struct spi_slave *slave, const void *dout, unsigned int bytesout,
+static int do_spi_xfer(struct spi_slave *slave, const void *dout,
-		void *din, unsigned int bytesin)
+		       unsigned int bytesout, void *din, unsigned int bytesin)
 {
 	struct spim_buffer	buff_0;
 	struct spim_buffer	buff_1;
 
-	if (!slave) {
-		printk(BIOS_ERR, "%s: Error: slave was not set up.\n",
-				__func__);
-		return -SPIM_API_NOT_INITIALISED;
-	}
-	if (!dout && !din) {
-		printk(BIOS_ERR, "%s: Error: both buffers are NULL.\n",
-				__func__);
-			return -SPIM_INVALID_TRANSFER_DESC;
-	}
 	/* If we only have a read or a write operation
 	 * the parameters for it will be put in the first buffer
 	 */
@@ -543,6 +532,48 @@ int spi_xfer(struct spi_slave *slave, const void *dout, unsigned int bytesout,
 	return spim_io(slave, &buff_0, (dout && din) ? &buff_1 : NULL);
 }
 
+int spi_xfer(struct spi_slave *slave, const void *dout, unsigned int bytesout,
+	     void *din, unsigned int bytesin)
+{
+	unsigned int in_sz, out_sz;
+	int ret;
+
+	if (!slave) {
+		printk(BIOS_ERR, "%s: Error: slave was not set up.\n",
+				__func__);
+		return -SPIM_API_NOT_INITIALISED;
+	}
+	if (!dout && !din) {
+		printk(BIOS_ERR, "%s: Error: both buffers are NULL.\n",
+				__func__);
+			return -SPIM_INVALID_TRANSFER_DESC;
+	}
+
+	while (bytesin || bytesout) {
+		in_sz = min(IMGTEC_SPI_MAX_TRANSFER_SIZE, bytesin);
+		out_sz = min(IMGTEC_SPI_MAX_TRANSFER_SIZE, bytesout);
+
+		ret = do_spi_xfer(slave, dout, out_sz, din, in_sz);
+		if (ret)
+			return ret;
+
+		bytesin -= in_sz;
+		bytesout -= out_sz;
+
+		if (bytesin)
+			din += in_sz;
+		else
+			din = NULL;
+
+		if (bytesout)
+			dout += out_sz;
+		else
+			dout = NULL;
+	}
+
+	return SPIM_OK;
+}
+
 unsigned int spi_crop_chunk(unsigned int cmd_len, unsigned int buf_len)
 {
 	return min(IMGTEC_SPI_MAX_TRANSFER_SIZE, buf_len);