spi: AMD SPI controller driver bug fix and cleanups

Merge series from Cristian Ciocaltea <cristian.ciocaltea@collabora.com>:

This patch series addresses an issue in the spi-amd driver and, while
there, performs some additional cleanups, like simplifying the error
handling in the probe function and removing an unused struct member.

For improving code readability, it also adds some kernel-doc comments.

drivers/spi/spi-amd.c

@@ -33,20 +33,30 @@
 #define AMD_SPI_RX_COUNT_REG	0x4B
 #define AMD_SPI_STATUS_REG	0x4C
 
+#define AMD_SPI_FIFO_SIZE	70
 #define AMD_SPI_MEM_SIZE	200
 
 /* M_CMD OP codes for SPI */
 #define AMD_SPI_XFER_TX		1
 #define AMD_SPI_XFER_RX		2
 
+/**
+ * enum amd_spi_versions - SPI controller versions
+ * @AMD_SPI_V1:		AMDI0061 hardware version
+ * @AMD_SPI_V2:		AMDI0062 hardware version
+ */
 enum amd_spi_versions {
-	AMD_SPI_V1 = 1,	/* AMDI0061 */
-	AMD_SPI_V2,	/* AMDI0062 */
+	AMD_SPI_V1 = 1,
+	AMD_SPI_V2,
 };
 
+/**
+ * struct amd_spi - SPI driver instance
+ * @io_remap_addr:	Start address of the SPI controller registers
+ * @version:		SPI controller hardware version
+ */
 struct amd_spi {
 	void __iomem *io_remap_addr;
-	unsigned long io_base_addr;
 	enum amd_spi_versions version;
 };
 
@@ -270,27 +280,29 @@ static int amd_spi_master_transfer(struct spi_master *master,
 	return 0;
 }
 
+static size_t amd_spi_max_transfer_size(struct spi_device *spi)
+{
+	return AMD_SPI_FIFO_SIZE;
+}
+
 static int amd_spi_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct spi_master *master;
 	struct amd_spi *amd_spi;
-	int err = 0;
+	int err;
 
 	/* Allocate storage for spi_master and driver private data */
-	master = spi_alloc_master(dev, sizeof(struct amd_spi));
-	if (!master) {
-		dev_err(dev, "Error allocating SPI master\n");
-		return -ENOMEM;
-	}
+	master = devm_spi_alloc_master(dev, sizeof(struct amd_spi));
+	if (!master)
+		return dev_err_probe(dev, -ENOMEM, "Error allocating SPI master\n");
 
 	amd_spi = spi_master_get_devdata(master);
 	amd_spi->io_remap_addr = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(amd_spi->io_remap_addr)) {
-		err = PTR_ERR(amd_spi->io_remap_addr);
-		dev_err(dev, "error %d ioremap of SPI registers failed\n", err);
-		goto err_free_master;
-	}
+	if (IS_ERR(amd_spi->io_remap_addr))
+		return dev_err_probe(dev, PTR_ERR(amd_spi->io_remap_addr),
+				     "ioremap of SPI registers failed\n");
+
 	dev_dbg(dev, "io_remap_address: %p\n", amd_spi->io_remap_addr);
 
 	amd_spi->version = (enum amd_spi_versions) device_get_match_data(dev);
@@ -302,20 +314,15 @@ static int amd_spi_probe(struct platform_device *pdev)
 	master->flags = SPI_MASTER_HALF_DUPLEX;
 	master->setup = amd_spi_master_setup;
 	master->transfer_one_message = amd_spi_master_transfer;
+	master->max_transfer_size = amd_spi_max_transfer_size;
+	master->max_message_size = amd_spi_max_transfer_size;
 
 	/* Register the controller with SPI framework */
 	err = devm_spi_register_master(dev, master);
-	if (err) {
-		dev_err(dev, "error %d registering SPI controller\n", err);
-		goto err_free_master;
-	}
+	if (err)
+		return dev_err_probe(dev, err, "error registering SPI controller\n");
 
 	return 0;
-
-err_free_master:
-	spi_master_put(master);
-
-	return err;
 }
 
 #ifdef CONFIG_ACPI