[RFC/PATCH 2/2] spi: dw-spi: Pointers select 16b vs. 32b DesignWare access

[<tthayer@opensource.altera.com>]

From: Thor Thayer <tthayer@opensource.altera.com>

Altera's Arria10 SoC requires a 32 bit access for peripherals.
The current spi-dw driver uses 16bit accesses in some locations.
Use function pointers to support 32 bit accesses and not break
legacy 16 bit access.

Signed-off-by: Thor Thayer <tthayer@opensource.altera.com>
---
 drivers/spi/spi-dw-mmio.c |    7 ++++++-
 drivers/spi/spi-dw.c      |   38 ++++++++++++++++++++++----------------
 drivers/spi/spi-dw.h      |   10 ++++++----
 3 files changed, 34 insertions(+), 21 deletions(-)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index eb03e12..ee77005 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->dwread = dw_readl;
+			dws->dwwrite = dw_writel;
+		}
+	}
 
 	dws->num_cs = num_cs;
 
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 05af817..614de7f 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -149,7 +149,7 @@ 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->dwread(dws, DW_SPI_TXFLR);
 
 	/*
 	 * Another concern is about the tx/rx mismatch, we
@@ -170,7 +170,7 @@ 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->dwread(dws, DW_SPI_RXFLR));
 }
 
 static void dw_writer(struct dw_spi *dws)
@@ -186,7 +186,7 @@ static void dw_writer(struct dw_spi *dws)
 			else
 				txw = *(u16 *)(dws->tx);
 		}
-		dw_writew(dws, DW_SPI_DR, txw);
+		dws->dwwrite(dws, DW_SPI_DR, txw);
 		dws->tx += dws->n_bytes;
 	}
 }
@@ -194,10 +194,10 @@ static void dw_writer(struct dw_spi *dws)
 static void dw_reader(struct dw_spi *dws)
 {
 	u32 max = rx_max(dws);
-	u16 rxw;
+	u32 rxw;
 
 	while (max--) {
-		rxw = dw_readw(dws, DW_SPI_DR);
+		rxw = dws->dwread(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)
@@ -299,13 +299,13 @@ EXPORT_SYMBOL_GPL(dw_spi_xfer_done);
 
 static irqreturn_t interrupt_transfer(struct dw_spi *dws)
 {
-	u16 irq_status = dw_readw(dws, DW_SPI_ISR);
+	u32 irq_status = dws->dwread(dws, DW_SPI_ISR);
 
 	/* Error handling */
 	if (irq_status & (SPI_INT_TXOI | SPI_INT_RXOI | SPI_INT_RXUI)) {
-		dw_readw(dws, DW_SPI_TXOICR);
-		dw_readw(dws, DW_SPI_RXOICR);
-		dw_readw(dws, DW_SPI_RXUICR);
+		dws->dwread(dws, DW_SPI_TXOICR);
+		dws->dwread(dws, DW_SPI_RXOICR);
+		dws->dwread(dws, DW_SPI_RXUICR);
 		int_error_stop(dws, "interrupt_transfer: fifo overrun/underrun");
 		return IRQ_HANDLED;
 	}
@@ -329,7 +329,7 @@ static irqreturn_t interrupt_transfer(struct dw_spi *dws)
 static irqreturn_t dw_spi_irq(int irq, void *dev_id)
 {
 	struct dw_spi *dws = dev_id;
-	u16 irq_status = dw_readw(dws, DW_SPI_ISR) & 0x3f;
+	u32 irq_status = dws->dwread(dws, DW_SPI_ISR) & 0x3f;
 
 	if (!irq_status)
 		return IRQ_NONE;
@@ -473,10 +473,11 @@ static void pump_transfers(unsigned long data)
 	 *	2. clk_div is changed
 	 *	3. control value changes
 	 */
-	if (dw_readw(dws, DW_SPI_CTRL0) != cr0 || cs_change || clk_div || imask) {
+	if (dws->dwread(dws, DW_SPI_CTRL0) != cr0 ||
+	    cs_change || clk_div || imask) {
 		spi_enable_chip(dws, 0);
 
-		dw_writew(dws, DW_SPI_CTRL0, cr0);
+		dws->dwwrite(dws, DW_SPI_CTRL0, cr0);
 
 		spi_set_clk(dws, chip->clk_div);
 		spi_chip_sel(dws, spi, 1);
@@ -486,7 +487,7 @@ static void pump_transfers(unsigned long data)
 		if (imask)
 			spi_umask_intr(dws, imask);
 		if (txlevel)
-			dw_writew(dws, DW_SPI_TXFLTR, txlevel);
+			dws->dwwrite(dws, DW_SPI_TXFLTR, txlevel);
 
 		spi_enable_chip(dws, 1);
 	}
@@ -618,11 +619,11 @@ 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->dwwrite(dws, DW_SPI_TXFLTR, fifo);
+			if (fifo != dws->dwread(dws, DW_SPI_TXFLTR))
 				break;
 		}
-		dw_writew(dws, DW_SPI_TXFLTR, 0);
+		dws->dwwrite(dws, DW_SPI_TXFLTR, 0);
 
 		dws->fifo_len = (fifo == 1) ? 0 : fifo;
 		dev_dbg(dev, "Detected FIFO size: %u bytes\n", dws->fifo_len);
@@ -647,6 +648,11 @@ 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->dwread)
+		dws->dwread = dw_readw;
+	if (!dws->dwwrite)
+		dws->dwwrite = dw_writew;
+
 	ret = devm_request_irq(dev, dws->irq, dw_spi_irq, IRQF_SHARED,
 			dws->name, dws);
 	if (ret < 0) {
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 3d32be6..5ca2407 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -150,6 +150,8 @@ struct dw_spi {
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *debugfs;
 #endif
+	u32 (*dwread)(struct dw_spi *dws, u32 offset);
+	void (*dwwrite)(struct dw_spi *dws, u32 offset, u16 val);
 };
 
 static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
@@ -157,14 +159,14 @@ static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
 	return __raw_readl(dws->regs + offset);
 }
 
-static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 val)
+static inline void dw_writel(struct dw_spi *dws, u32 offset, u16 val)
 {
-	__raw_writel(val, dws->regs + offset);
+	__raw_writel((u32)val, dws->regs + offset);
 }
 
-static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
+static inline u32 dw_readw(struct dw_spi *dws, u32 offset)
 {
-	return __raw_readw(dws->regs + offset);
+	return (u32)__raw_readw(dws->regs + offset);
 }
 
 static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
-- 
1.7.9.5