[RFC/PATCHv2 3/3] spi: dw-spi: Pointers select 16b vs. 32b DesignWare access

[<tthayer-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org>]

From: Thor Thayer <tthayer-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org>

Altera's Arria10 SoC interconnect requires a 32 bit write for APB
peripherals. The current spi-dw driver uses 16bit accesses in
some locations. Use function pointers to support 32 bit accesses
but retain legacy 16 bit access.

Signed-off-by: Thor Thayer <tthayer-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org>
---
 drivers/spi/spi-dw-mmio.c |    7 ++++++-
 drivers/spi/spi-dw.c      |   29 +++++++++++++++++------------
 drivers/spi/spi-dw.h      |   12 ++++++++++++
 3 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index eb03e12..c4fe9e9 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -76,8 +76,13 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
 
 	num_cs = 4;
 
-	if (pdev->dev.of_node)
+	if (pdev->dev.of_node) {
 		of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs);
+		if (of_property_read_bool(pdev->dev.of_node, "32bit_access")) {
+			dws->read_w = dw_readw32;
+			dws->write_w = dw_writew32;
+		}
+	}
 
 	dws->num_cs = num_cs;
 
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index c5fa2be..d008791 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -157,7 +157,7 @@ static inline u32 tx_max(struct dw_spi *dws)
 	u32 tx_left, tx_room, rxtx_gap;
 
 	tx_left = (dws->tx_end - dws->tx) / dws->n_bytes;
-	tx_room = dws->fifo_len - dw_readw(dws, DW_SPI_TXFLR);
+	tx_room = dws->fifo_len - dws->read_w(dws, DW_SPI_TXFLR);
 
 	/*
 	 * Another concern is about the tx/rx mismatch, we
@@ -178,7 +178,7 @@ static inline u32 rx_max(struct dw_spi *dws)
 {
 	u32 rx_left = (dws->rx_end - dws->rx) / dws->n_bytes;
 
-	return min_t(u32, rx_left, dw_readw(dws, DW_SPI_RXFLR));
+	return min_t(u32, rx_left, dws->read_w(dws, DW_SPI_RXFLR));
 }
 
 static void dw_writer(struct dw_spi *dws)
@@ -194,7 +194,7 @@ static void dw_writer(struct dw_spi *dws)
 			else
 				txw = *(u16 *)(dws->tx);
 		}
-		dw_writew(dws, DW_SPI_DR, txw);
+		dws->write_w(dws, DW_SPI_DR, txw);
 		dws->tx += dws->n_bytes;
 	}
 }
@@ -205,7 +205,7 @@ static void dw_reader(struct dw_spi *dws)
 	u16 rxw;
 
 	while (max--) {
-		rxw = dw_readw(dws, DW_SPI_DR);
+		rxw = dws->read_w(dws, DW_SPI_DR);
 		/* Care rx only if the transfer's original "rx" is not null */
 		if (dws->rx_end - dws->len) {
 			if (dws->n_bytes == 1)
@@ -254,11 +254,11 @@ static void int_error_stop(struct dw_spi *dws, const char *msg)
 
 static irqreturn_t interrupt_transfer(struct dw_spi *dws)
 {
-	u16 irq_status = dw_readw(dws, DW_SPI_ISR);
+	u16 irq_status = dws->read_w(dws, DW_SPI_ISR);
 
 	/* Error handling */
 	if (irq_status & (SPI_INT_TXOI | SPI_INT_RXOI | SPI_INT_RXUI)) {
-		dw_readw(dws, DW_SPI_ICR);
+		dws->read_w(dws, DW_SPI_ICR);
 		int_error_stop(dws, "interrupt_transfer: fifo overrun/underrun");
 		return IRQ_HANDLED;
 	}
@@ -283,7 +283,7 @@ static irqreturn_t dw_spi_irq(int irq, void *dev_id)
 {
 	struct spi_master *master = dev_id;
 	struct dw_spi *dws = spi_master_get_devdata(master);
-	u16 irq_status = dw_readw(dws, DW_SPI_ISR) & 0x3f;
+	u16 irq_status = dws->read_w(dws, DW_SPI_ISR) & 0x3f;
 
 	if (!irq_status)
 		return IRQ_NONE;
@@ -379,7 +379,7 @@ static int dw_spi_transfer_one(struct spi_master *master,
 		cr0 |= (chip->tmode << SPI_TMOD_OFFSET);
 	}
 
-	dw_writew(dws, DW_SPI_CTRL0, cr0);
+	dws->write_w(dws, DW_SPI_CTRL0, cr0);
 
 	/* Check if current transfer is a DMA transaction */
 	dws->dma_mapped = map_dma_buffers(master, spi, transfer);
@@ -393,7 +393,7 @@ static int dw_spi_transfer_one(struct spi_master *master,
 	 */
 	if (!dws->dma_mapped && !chip->poll_mode) {
 		txlevel = min_t(u16, dws->fifo_len / 2, dws->len / dws->n_bytes);
-		dw_writew(dws, DW_SPI_TXFLTR, txlevel);
+		dws->write_w(dws, DW_SPI_TXFLTR, txlevel);
 
 		/* Set the interrupt mask */
 		imask |= SPI_INT_TXEI | SPI_INT_TXOI |
@@ -516,11 +516,11 @@ static void spi_hw_init(struct device *dev, struct dw_spi *dws)
 		u32 fifo;
 
 		for (fifo = 1; fifo < 256; fifo++) {
-			dw_writew(dws, DW_SPI_TXFLTR, fifo);
-			if (fifo != dw_readw(dws, DW_SPI_TXFLTR))
+			dws->write_w(dws, DW_SPI_TXFLTR, fifo);
+			if (fifo != dws->read_w(dws, DW_SPI_TXFLTR))
 				break;
 		}
-		dw_writew(dws, DW_SPI_TXFLTR, 0);
+		dws->write_w(dws, DW_SPI_TXFLTR, 0);
 
 		dws->fifo_len = (fifo == 1) ? 0 : fifo;
 		dev_dbg(dev, "Detected FIFO size: %u bytes\n", dws->fifo_len);
@@ -545,6 +545,11 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
 	dws->dma_addr = (dma_addr_t)(dws->paddr + 0x60);
 	snprintf(dws->name, sizeof(dws->name), "dw_spi%d", dws->bus_num);
 
+	if (!dws->read_w)
+		dws->read_w = dw_readw;
+	if (!dws->write_w)
+		dws->write_w = dw_writew;
+
 	ret = devm_request_irq(dev, dws->irq, dw_spi_irq, IRQF_SHARED,
 			dws->name, master);
 	if (ret < 0) {
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 855bfdd..1df09e2 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -141,6 +141,8 @@ struct dw_spi {
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *debugfs;
 #endif
+	u16 (*read_w)(struct dw_spi *dws, u32 offset);
+	void (*write_w)(struct dw_spi *dws, u32 offset, u16 val);
 };
 
 static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
@@ -163,6 +165,16 @@ static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
 	__raw_writew(val, dws->regs + offset);
 }
 
+static inline u16 dw_readw32(struct dw_spi *dws, u32 offset)
+{
+	return (u16)__raw_readl(dws->regs + offset);
+}
+
+static inline void dw_writew32(struct dw_spi *dws, u32 offset, u16 val)
+{
+	__raw_writel((u32)val, dws->regs + offset);
+}
+
 static inline void spi_enable_chip(struct dw_spi *dws, int enable)
 {
 	dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));
-- 
1.7.9.5

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