sdhc: sdhc_spi: compile-time determine if sdhc_ones needed

Use the new `SPI_MOSI_OVERRUN_DT` macro to determine at compile-time
whether the 512 byte array of `sdhc_ones` is required.

(cherry picked from commit 5d87cd6)

Original-Signed-off-by: Jordan Yates <jordan@embeint.com>
GitOrigin-RevId: 5d87cd6
Cr-Build-Id: 8740178774340358353
Cr-Build-Url: https://cr-buildbucket.appspot.com/build/8740178774340358353
Copybot-Job-Name: zephyr-main-copybot-downstream
Change-Id: I334bfe317e86e6943c5b4e1a63f25de5a2c6926c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/5773301
Tested-by: ChromeOS Prod (Robot) <chromeos-ci-prod@chromeos-bot.iam.gserviceaccount.com>
Commit-Queue: Jeremy Bettis <jbettis@chromium.org>
Reviewed-by: Jeremy Bettis <jbettis@chromium.org>
Tested-by: Jeremy Bettis <jbettis@chromium.org>

drivers/sdhc/sdhc_spi.c

@@ -21,11 +21,19 @@ LOG_MODULE_REGISTER(sdhc_spi, CONFIG_SDHC_LOG_LEVEL);
 #define SPI_R1B_TIMEOUT_MS 3000
 #define SD_SPI_SKIP_RETRIES 1000000
 
-/* The SD protocol requires sending ones while reading but Zephyr
- * defaults to writing zeros. This block of 512 bytes is used for writing
- * 0xff while we read data blocks. Should remain const so this buffer is
- * stored in flash.
+#define _INST_REQUIRES_EXPLICIT_FF(inst) (SPI_MOSI_OVERRUN_DT(DT_INST_BUS(inst)) != 0xFF) ||
+
+/* The SD protocol requires sending ones while reading but the Zephyr
+ * SPI API defers the choice of default values to the drivers.
+ *
+ * For drivers that we know will send ones we can avoid allocating a
+ * 512 byte array of ones and remove the limit on the number of bytes
+ * that can be read in a single transaction.
  */
+#define ANY_INST_REQUIRES_EXPLICIT_FF DT_INST_FOREACH_STATUS_OKAY(_INST_REQUIRES_EXPLICIT_FF) 0
+
+#if ANY_INST_REQUIRES_EXPLICIT_FF
+
 static const uint8_t sdhc_ones[] = {
 	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
 	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
@@ -78,6 +86,8 @@ static const uint8_t sdhc_ones[] = {
 
 BUILD_ASSERT(sizeof(sdhc_ones) == 512, "0xFF array for SDHC must be 512 bytes");
 
+#endif /* ANY_INST_REQUIRES_EXPLICIT_FF */
+
 struct sdhc_spi_config {
 	const struct device *spi_dev;
 	const struct gpio_dt_spec pwr_gpio;
@@ -97,6 +107,7 @@ struct sdhc_spi_data {
 static int sdhc_spi_rx(const struct device *spi_dev, struct spi_config *spi_cfg,
 	uint8_t *buf, int len)
 {
+#if ANY_INST_REQUIRES_EXPLICIT_FF
 	struct spi_buf tx_bufs[] = {
 		{
 			.buf = (uint8_t *)sdhc_ones,
@@ -108,6 +119,10 @@ static int sdhc_spi_rx(const struct device *spi_dev, struct spi_config *spi_cfg,
 		.buffers = tx_bufs,
 		.count = 1,
 	};
+	const struct spi_buf_set *tx_ptr = &tx;
+#else
+	const struct spi_buf_set *tx_ptr = NULL;
+#endif /* ANY_INST_REQUIRES_EXPLICIT_FF */
 
 	struct spi_buf rx_bufs[] = {
 		{
@@ -121,7 +136,7 @@ static int sdhc_spi_rx(const struct device *spi_dev, struct spi_config *spi_cfg,
 		.count = 1,
 	};
 
-	return spi_transceive(spi_dev, spi_cfg, &tx, &rx);
+	return spi_transceive(spi_dev, spi_cfg, tx_ptr, &rx);
 }
 
 static int sdhc_spi_init_card(const struct device *dev)
@@ -432,10 +447,14 @@ static int sdhc_spi_read_data(const struct device *dev, struct sdhc_data *data)
 	int ret;
 	uint8_t crc[SD_SPI_CRC16_SIZE + 1];
 
-	/* The SPI API defaults to sending 0x00 when no TX buffer is
-	 * provided, so we are limited to 512 byte reads
-	 * (unless we increase the size of SDHC buffer)
+#if ANY_INST_REQUIRES_EXPLICIT_FF
+	/* If the driver requires explicit 0xFF bytes on receive, we
+	 * are limited to receiving the size of the sdhc_ones buffer
 	 */
+	if (data->block_size > sizeof(sdhc_ones)) {
+		return -ENOTSUP;
+	}
+
 	const struct spi_buf tx_bufs[] = {
 		{
 			.buf = (uint8_t *)sdhc_ones,
@@ -447,6 +466,10 @@ static int sdhc_spi_read_data(const struct device *dev, struct sdhc_data *data)
 		.buffers = tx_bufs,
 		.count = 1,
 	};
+	const struct spi_buf_set *tx_ptr = &tx;
+#else
+	const struct spi_buf_set *tx_ptr = NULL;
+#endif /* ANY_INST_REQUIRES_EXPLICIT_FF */
 
 	struct spi_buf rx_bufs[] = {
 		{
@@ -460,10 +483,6 @@ static int sdhc_spi_read_data(const struct device *dev, struct sdhc_data *data)
 		.count = 1,
 	};
 
-	if (data->block_size > 512) {
-		/* SPI max BLKLEN is 512 */
-		return -ENOTSUP;
-	}
 
 	/* Read bytes until data stream starts. SD will send 0xff until
 	 * data is available
@@ -480,7 +499,7 @@ static int sdhc_spi_read_data(const struct device *dev, struct sdhc_data *data)
 	/* Read blocks until we are out of data */
 	while (remaining--) {
 		ret = spi_transceive(config->spi_dev,
-			dev_data->spi_cfg, &tx, &rx);
+			dev_data->spi_cfg, tx_ptr, &rx);
 		if (ret) {
 			LOG_ERR("Data write failed");
 			return ret;