drivers/spi: reduce confusion in the API

Julius brought up confusion about the current spi api in [1]. In order
alleviate the confusion stemming from supporting x86 spi flash
controllers:

- Remove spi_xfer_two_vectors() which was fusing transactions to
  accomodate the limitations of the spi controllers themselves.
- Add spi_flash_vector_helper() for the x86 spi flash controllers to
  utilize in validating driver/controller current assumptions.
- Remove the xfer() callback in the x86 spi flash drivers which
  will trigger an error as these controllers can't support the api.

[1] https://mail.coreboot.org/pipermail/coreboot/2018-April/086561.html

Change-Id: Id88adc6ad5234c29a739d43521c5f344bb7d3217
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/25745
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/drivers/spi/spi-generic.c

@@ -146,56 +146,3 @@ int spi_setup_slave(unsigned int bus, unsigned int cs, struct spi_slave *slave)
 
 	return 0;
 }
-
-static int spi_xfer_combine_two_vectors(const struct spi_slave *slave,
-					struct spi_op *v1, struct spi_op *v2)
-{
-	struct spi_op op = {
-		.dout = v1->dout, .bytesout = v1->bytesout,
-		.din = v2->din, .bytesin = v2->bytesin,
-	};
-	int ret;
-
-	/*
-	 * Combine two vectors only if:
-	 * v1 has non-NULL dout and NULL din and
-	 * v2 has non-NULL din and NULL dout and
-	 *
-	 * In all other cases, do not combine the two vectors.
-	 */
-	if ((!v1->dout || v1->din) || (v2->dout || !v2->din))
-		return -1;
-
-	ret = spi_xfer_single_op(slave, &op);
-	v1->status = v2->status = op.status;
-
-	return ret;
-}
-
-/*
- * Helper function to allow chipsets to combine two vectors if possible. This
- * function can only handle upto 2 vectors.
- *
- * Two vectors are combined if first vector has a non-NULL dout and NULL din and
- * second vector has a non-NULL din and NULL dout. Otherwise, each vector is
- * operated upon one at a time.
- *
- * Returns 0 on success and non-zero on failure.
- */
-int spi_xfer_two_vectors(const struct spi_slave *slave,
-			struct spi_op vectors[], size_t count)
-{
-	int ret;
-
-	assert (count <= 2);
-
-	if (count == 2) {
-		ret = spi_xfer_combine_two_vectors(slave, &vectors[0],
-						&vectors[1]);
-
-		if (!ret || (vectors[0].status != SPI_OP_NOT_EXECUTED))
-			return ret;
-	}
-
-	return spi_xfer_vector_default(slave, vectors, count);
-}

src/drivers/spi/spi_flash.c

@@ -519,3 +519,51 @@ int spi_flash_ctrlr_protect_region(const struct spi_flash *flash,
 
 	return -1;
 }
+
+int spi_flash_vector_helper(const struct spi_slave *slave,
+	struct spi_op vectors[], size_t count,
+	int (*func)(const struct spi_slave *slave, const void *dout,
+		    size_t bytesout, void *din, size_t bytesin))
+{
+	int ret;
+	void *din;
+	size_t bytes_in;
+
+	if (count < 1 || count > 2)
+		return -1;
+
+	/* SPI flash commands always have a command first... */
+	if (!vectors[0].dout || !vectors[0].bytesout)
+		return -1;
+	/* And not read any data during the command. */
+	if (vectors[0].din || vectors[0].bytesin)
+		return -1;
+
+	if (count == 2) {
+		/* If response bytes requested ensure the buffer is valid. */
+		if (vectors[1].bytesin && !vectors[1].din)
+			return -1;
+		/* No sends can accompany a receive. */
+		if (vectors[1].dout || vectors[1].bytesout)
+			return -1;
+		din = vectors[1].din;
+		bytes_in = vectors[1].bytesin;
+	} else {
+		din = NULL;
+		bytes_in = 0;
+	}
+
+	ret = func(slave, vectors[0].dout, vectors[0].bytesout, din, bytes_in);
+
+	if (ret) {
+		vectors[0].status = SPI_OP_FAILURE;
+		if (count == 2)
+			vectors[1].status = SPI_OP_FAILURE;
+	} else {
+		vectors[0].status = SPI_OP_SUCCESS;
+		if (count == 2)
+			vectors[1].status = SPI_OP_SUCCESS;
+	}
+
+	return ret;
+}

src/include/spi-generic.h

@@ -109,7 +109,10 @@ enum {
 };
 
 /*-----------------------------------------------------------------------
- * Representation of a SPI controller.
+ * Representation of a SPI controller. Note the xfer() and xfer_vector()
+ * callbacks are meant to process full duplex transactions. If the
+ * controller cannot handle these transactions then return an error when
+ * din and dout are both set. See spi_xfer() below for more details.
  *
  * claim_bus:		Claim SPI bus and prepare for communication.
  * release_bus:	Release SPI bus.
@@ -232,6 +235,10 @@ void spi_release_bus(const struct spi_slave *slave);
  *   din:	Pointer to a string of bytes that will be filled in.
  *   bytesin:	How many bytes to read.
  *
+ * Note that din and dout are transferred simulataneously in a full duplex
+ * transaction. The number of clocks within one transaction is calculated
+ * as: MAX(bytesout*8, bytesin*8).
+ *
  *   Returns: 0 on success, not 0 on failure
  */
 int spi_xfer(const struct spi_slave *slave, const void *dout, size_t bytesout,
@@ -281,23 +288,4 @@ static inline int spi_w8r8(const struct spi_slave *slave, unsigned char byte)
 	return ret < 0 ? ret : din[1];
 }
 
-/*
- * Helper function to allow chipsets to combine two vectors if possible. It can
- * only handle upto 2 vectors.
- *
- * This function is provided to support command-response kind of transactions
- * expected by users like flash. Some special SPI flash controllers can handle
- * such command-response operations in a single transaction. For these special
- * controllers, separate command and response vectors can be combined into a
- * single operation.
- *
- * Two vectors are combined if first vector has a non-NULL dout and NULL din and
- * second vector has a non-NULL din and NULL dout. Otherwise, each vector is
- * operated upon one at a time.
- *
- * Returns 0 on success and non-zero on failure.
- */
-int spi_xfer_two_vectors(const struct spi_slave *slave,
-			struct spi_op vectors[], size_t count);
-
 #endif	/* _SPI_GENERIC_H_ */

src/include/spi_flash.h

@@ -125,4 +125,18 @@ const struct spi_flash *boot_device_spi_flash(void);
 int spi_flash_ctrlr_protect_region(const struct spi_flash *flash,
 					const struct region *region);
 
+/*
+ * This function is provided to support spi flash command-response transactions.
+ * Only 2 vectors are supported and the 'func' is called with appropriate
+ * write and read buffers together. This can be used for chipsets that
+ * have specific spi flash controllers that don't conform to the normal
+ * spi xfer API because they are specialized controllers and not generic.
+ *
+ * Returns 0 on success and non-zero on failure.
+ */
+int spi_flash_vector_helper(const struct spi_slave *slave,
+	struct spi_op vectors[], size_t count,
+	int (*func)(const struct spi_slave *slave, const void *dout,
+		    size_t bytesout, void *din, size_t bytesin));
+
 #endif /* _SPI_FLASH_H_ */

src/soc/amd/stoneyridge/spi.c

@@ -181,9 +181,14 @@ int chipset_volatile_group_end(const struct spi_flash *flash)
 	return 0;
 }
 
+static int xfer_vectors(const struct spi_slave *slave,
+			struct spi_op vectors[], size_t count)
+{
+	return spi_flash_vector_helper(slave, vectors, count, spi_ctrlr_xfer);
+}
+
 static const struct spi_ctrlr spi_ctrlr = {
-	.xfer = spi_ctrlr_xfer,
-	.xfer_vector = spi_xfer_two_vectors,
+	.xfer_vector = xfer_vectors,
 	.max_xfer_size = SPI_FIFO_DEPTH,
 	.flags = SPI_CNTRLR_DEDUCT_CMD_LEN | SPI_CNTRLR_DEDUCT_OPCODE_LEN,
 };

src/soc/intel/baytrail/spi.c

@@ -607,9 +607,14 @@ static int spi_ctrlr_xfer(const struct spi_slave *slave, const void *dout,
 	return 0;
 }
 
+static int xfer_vectors(const struct spi_slave *slave,
+			struct spi_op vectors[], size_t count)
+{
+	return spi_flash_vector_helper(slave, vectors, count, spi_ctrlr_xfer);
+}
+
 static const struct spi_ctrlr spi_ctrlr = {
-	.xfer = spi_ctrlr_xfer,
-	.xfer_vector = spi_xfer_two_vectors,
+	.xfer_vector = xfer_vectors,
 	.max_xfer_size = member_size(ich9_spi_regs, fdata),
 };
 

src/soc/intel/braswell/spi.c

@@ -591,9 +591,14 @@ static int spi_ctrlr_xfer(const struct spi_slave *slave, const void *dout,
 	return 0;
 }
 
+static int xfer_vectors(const struct spi_slave *slave,
+			struct spi_op vectors[], size_t count)
+{
+	return spi_flash_vector_helper(slave, vectors, count, spi_ctrlr_xfer);
+}
+
 static const struct spi_ctrlr spi_ctrlr = {
-	.xfer = spi_ctrlr_xfer,
-	.xfer_vector = spi_xfer_two_vectors,
+	.xfer_vector = xfer_vectors,
 	.max_xfer_size = member_size(ich9_spi_regs, fdata),
 };
 

src/soc/intel/broadwell/spi.c

@@ -650,9 +650,14 @@ static int spi_flash_protect(const struct spi_flash *flash,
 	return 0;
 }
 
+static int xfer_vectors(const struct spi_slave *slave,
+			struct spi_op vectors[], size_t count)
+{
+	return spi_flash_vector_helper(slave, vectors, count, spi_ctrlr_xfer);
+}
+
 static const struct spi_ctrlr spi_ctrlr = {
-	.xfer = spi_ctrlr_xfer,
-	.xfer_vector = spi_xfer_two_vectors,
+	.xfer_vector = xfer_vectors,
 	.max_xfer_size = member_size(ich9_spi_regs, fdata),
 	.flash_protect = spi_flash_protect,
 };

src/soc/intel/fsp_baytrail/spi.c

@@ -588,9 +588,14 @@ spi_xfer_exit:
 	return 0;
 }
 
+static int xfer_vectors(const struct spi_slave *slave,
+			struct spi_op vectors[], size_t count)
+{
+	return spi_flash_vector_helper(slave, vectors, count, spi_ctrlr_xfer);
+}
+
 static const struct spi_ctrlr spi_ctrlr = {
-	.xfer = spi_ctrlr_xfer,
-	.xfer_vector = spi_xfer_two_vectors,
+	.xfer_vector = xfer_vectors,
 	.max_xfer_size = member_size(ich9_spi_regs, fdata),
 };
 

src/soc/intel/fsp_broadwell_de/spi.c

@@ -604,9 +604,14 @@ spi_xfer_exit:
 	return 0;
 }
 
+static int xfer_vectors(const struct spi_slave *slave,
+			struct spi_op vectors[], size_t count)
+{
+	return spi_flash_vector_helper(slave, vectors, count, spi_ctrlr_xfer);
+}
+
 static const struct spi_ctrlr spi_ctrlr = {
-	.xfer = spi_ctrlr_xfer,
-	.xfer_vector = spi_xfer_two_vectors,
+	.xfer_vector = xfer_vectors,
 	.max_xfer_size = member_size(ich9_spi_regs, fdata),
 };
 

src/southbridge/amd/agesa/hudson/spi.c

@@ -160,9 +160,14 @@ int chipset_volatile_group_end(const struct spi_flash *flash)
 	return 0;
 }
 
+static int xfer_vectors(const struct spi_slave *slave,
+			struct spi_op vectors[], size_t count)
+{
+	return spi_flash_vector_helper(slave, vectors, count, spi_ctrlr_xfer);
+}
+
 static const struct spi_ctrlr spi_ctrlr = {
-	.xfer = spi_ctrlr_xfer,
-	.xfer_vector = spi_xfer_two_vectors,
+	.xfer_vector = xfer_vectors,
 	.max_xfer_size = AMD_SB_SPI_TX_LEN,
 	.flags = SPI_CNTRLR_DEDUCT_CMD_LEN,
 };

src/southbridge/amd/cimx/sb800/spi.c

@@ -151,9 +151,14 @@ int chipset_volatile_group_end(const struct spi_flash *flash)
 	return 0;
 }
 
+static int xfer_vectors(const struct spi_slave *slave,
+			struct spi_op vectors[], size_t count)
+{
+	return spi_flash_vector_helper(slave, vectors, count, spi_ctrlr_xfer);
+}
+
 static const struct spi_ctrlr spi_ctrlr = {
-	.xfer = spi_ctrlr_xfer,
-	.xfer_vector = spi_xfer_two_vectors,
+	.xfer_vector = xfer_vectors,
 	.max_xfer_size = AMD_SB_SPI_TX_LEN,
 	.flags = SPI_CNTRLR_DEDUCT_CMD_LEN,
 };

src/southbridge/amd/sb700/spi.c

@@ -108,9 +108,14 @@ static int spi_ctrlr_xfer(const struct spi_slave *slave, const void *dout,
 	return 0;
 }
 
+static int xfer_vectors(const struct spi_slave *slave,
+			struct spi_op vectors[], size_t count)
+{
+	return spi_flash_vector_helper(slave, vectors, count, spi_ctrlr_xfer);
+}
+
 static const struct spi_ctrlr spi_ctrlr = {
-	.xfer = spi_ctrlr_xfer,
-	.xfer_vector = spi_xfer_two_vectors,
+	.xfer_vector = xfer_vectors,
 	.max_xfer_size = AMD_SB_SPI_TX_LEN,
 	.flags = SPI_CNTRLR_DEDUCT_CMD_LEN,
 };

src/southbridge/intel/common/spi.c

@@ -953,9 +953,14 @@ static int spi_flash_programmer_probe(const struct spi_slave *spi,
 	return 0;
 }
 
+static int xfer_vectors(const struct spi_slave *slave,
+			struct spi_op vectors[], size_t count)
+{
+	return spi_flash_vector_helper(slave, vectors, count, spi_ctrlr_xfer);
+}
+
 static const struct spi_ctrlr spi_ctrlr = {
-	.xfer = spi_ctrlr_xfer,
-	.xfer_vector = spi_xfer_two_vectors,
+	.xfer_vector = xfer_vectors,
 	.max_xfer_size = member_size(ich9_spi_regs, fdata),
 	.flash_probe = spi_flash_programmer_probe,
 };

src/southbridge/intel/fsp_rangeley/spi.c

@@ -719,9 +719,14 @@ spi_xfer_exit:
 	return 0;
 }
 
+static int xfer_vectors(const struct spi_slave *slave,
+			struct spi_op vectors[], size_t count)
+{
+	return spi_flash_vector_helper(slave, vectors, count, spi_ctrlr_xfer);
+}
+
 static const struct spi_ctrlr spi_ctrlr = {
-	.xfer = spi_ctrlr_xfer,
-	.xfer_vector = spi_xfer_two_vectors,
+	.xfer_vector = xfer_vectors,
 	.max_xfer_size = member_size(ich10_spi_regs, fdata),
 };