asoc: wcd-spi: use CMA memory for TX and RX buffer instead of kzalloc

In wcd-spi driver, the kzalloc is used to allocate memory for TX and
RX buffer. Those allocations are order4 or order5, which could fail
on some kernels. To avoid potential memory allocation failure, the CMA
region is used for those allocations by dma_alloc_coherent API.

Change-Id: I0a4d6c6b5e0e47f96187563272e63c3a006e469f
Signed-off-by: Xiaoyu Ye <[email protected]>

asoc/codecs/wcd-spi.c

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (c) 2016-2018, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2016-2019, The Linux Foundation. All rights reserved.
  */
 
 #include <linux/init.h>
@@ -8,6 +8,7 @@
 #include <linux/of.h>
 #include <linux/debugfs.h>
 #include <linux/delay.h>
+#include <linux/dma-mapping.h>
 #include <linux/bitops.h>
 #include <linux/spi/spi.h>
 #include <linux/regmap.h>
@@ -152,6 +153,10 @@ struct wcd_spi_priv {
 	/* Buffers to hold memory used for transfers */
 	void *tx_buf;
 	void *rx_buf;
+
+	/* DMA handles for transfer buffers */
+	dma_addr_t tx_dma;
+	dma_addr_t rx_dma;
 };
 
 enum xfer_request {
@@ -1371,17 +1376,20 @@ static int wcd_spi_component_bind(struct device *dev,
 	spi_message_add_tail(&wcd_spi->xfer2[1], &wcd_spi->msg2);
 
 	/* Pre-allocate the buffers */
-	wcd_spi->tx_buf = kzalloc(WCD_SPI_RW_MAX_BUF_SIZE,
-				  GFP_KERNEL | GFP_DMA);
+	wcd_spi->tx_buf = dma_zalloc_coherent(&spi->dev,
+					      WCD_SPI_RW_MAX_BUF_SIZE,
+					      &wcd_spi->tx_dma, GFP_KERNEL);
 	if (!wcd_spi->tx_buf) {
 		ret = -ENOMEM;
 		goto done;
 	}
 
-	wcd_spi->rx_buf = kzalloc(WCD_SPI_RW_MAX_BUF_SIZE,
-				  GFP_KERNEL | GFP_DMA);
+	wcd_spi->rx_buf = dma_zalloc_coherent(&spi->dev,
+					      WCD_SPI_RW_MAX_BUF_SIZE,
+					      &wcd_spi->rx_dma, GFP_KERNEL);
 	if (!wcd_spi->rx_buf) {
-		kfree(wcd_spi->tx_buf);
+		dma_free_coherent(&spi->dev, WCD_SPI_RW_MAX_BUF_SIZE,
+				  wcd_spi->tx_buf, wcd_spi->tx_dma);
 		wcd_spi->tx_buf = NULL;
 		ret = -ENOMEM;
 		goto done;
@@ -1408,8 +1416,10 @@ static void wcd_spi_component_unbind(struct device *dev,
 	spi_transfer_del(&wcd_spi->xfer2[0]);
 	spi_transfer_del(&wcd_spi->xfer2[1]);
 
-	kfree(wcd_spi->tx_buf);
-	kfree(wcd_spi->rx_buf);
+	dma_free_coherent(&spi->dev, WCD_SPI_RW_MAX_BUF_SIZE,
+			  wcd_spi->tx_buf, wcd_spi->tx_dma);
+	dma_free_coherent(&spi->dev, WCD_SPI_RW_MAX_BUF_SIZE,
+			  wcd_spi->rx_buf, wcd_spi->rx_dma);
 	wcd_spi->tx_buf = NULL;
 	wcd_spi->rx_buf = NULL;
 }
@@ -1445,6 +1455,7 @@ static int wcd_spi_probe(struct spi_device *spi)
 	mutex_init(&wcd_spi->xfer_mutex);
 	INIT_DELAYED_WORK(&wcd_spi->clk_dwork, wcd_spi_clk_work);
 	init_completion(&wcd_spi->resume_comp);
+	arch_setup_dma_ops(&spi->dev, 0, 0, NULL, true);
 
 	wcd_spi->spi = spi;
 	spi_set_drvdata(spi, wcd_spi);