spi: davinci: add support for wait enable timeouts

Just enabling WAITENA in SPIFMTn register waits for the
enable signal from the slave indefinitely. Allow support
for finite waiting by adding support for c2e delay
(maximum time for addressed slave to respond) and t2e
delay (maximum time for slave to respond after transmit
data finished).

While at it, modify the T2C and C2T defines by prepending
the register name as is the convention followed for other
register field elsewhere in the driver.

Signed-off-by: Brian Niebuhr <bniebuhr@efjohnson.com>
Tested-By: Michael Williamson <michael.williamson@criticallink.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>

arch/arm/mach-davinci/include/mach/spi.h

@@ -43,6 +43,8 @@ struct davinci_spi_config {
 	u8	timer_disable;
 	u8	c2tdelay;
 	u8	t2cdelay;
+	u8	t2edelay;
+	u8	c2edelay;
 };
 
 #endif	/* __ARCH_ARM_DAVINCI_SPI_H */

drivers/spi/davinci_spi.c

@@ -78,6 +78,16 @@
 #define SPIBUF_TXFULL_MASK	BIT(29)
 #define SPIBUF_RXEMPTY_MASK	BIT(31)
 
+/* SPIDELAY */
+#define SPIDELAY_C2TDELAY_SHIFT 24
+#define SPIDELAY_C2TDELAY_MASK  (0xFF << SPIDELAY_C2TDELAY_SHIFT)
+#define SPIDELAY_T2CDELAY_SHIFT 16
+#define SPIDELAY_T2CDELAY_MASK  (0xFF << SPIDELAY_T2CDELAY_SHIFT)
+#define SPIDELAY_T2EDELAY_SHIFT 8
+#define SPIDELAY_T2EDELAY_MASK  (0xFF << SPIDELAY_T2EDELAY_SHIFT)
+#define SPIDELAY_C2EDELAY_SHIFT 0
+#define SPIDELAY_C2EDELAY_MASK  0xFF
+
 /* Error Masks */
 #define SPIFLG_DLEN_ERR_MASK		BIT(0)
 #define SPIFLG_TIMEOUT_MASK		BIT(1)
@@ -95,9 +105,6 @@
 #define SPIINT_TX_INTR		BIT(9)
 #define SPIINT_DMA_REQ_EN	BIT(16)
 
-#define SPI_T2CDELAY_SHIFT	16
-#define SPI_C2TDELAY_SHIFT	24
-
 /* SPI Controller registers */
 #define SPIGCR0		0x00
 #define SPIGCR1		0x04
@@ -363,6 +370,8 @@ static int davinci_spi_setup_transfer(struct spi_device *spi,
 
 	if (davinci_spi->version == SPI_VERSION_2) {
 
+		u32 delay = 0;
+
 		spifmt |= ((spicfg->wdelay << SPIFMT_WDELAY_SHIFT)
 							& SPIFMT_WDELAY_MASK);
 
@@ -372,15 +381,24 @@ static int davinci_spi_setup_transfer(struct spi_device *spi,
 		if (spicfg->parity_enable)
 			spifmt |= SPIFMT_PARITYENA_MASK;
 
-		if (spicfg->timer_disable)
+		if (spicfg->timer_disable) {
 			spifmt |= SPIFMT_DISTIMER_MASK;
-		else
-			iowrite32((spicfg->c2tdelay << SPI_C2TDELAY_SHIFT) |
-				  (spicfg->t2cdelay << SPI_T2CDELAY_SHIFT),
-				  davinci_spi->base + SPIDELAY);
+		} else {
+			delay |= (spicfg->c2tdelay << SPIDELAY_C2TDELAY_SHIFT)
+						& SPIDELAY_C2TDELAY_MASK;
+			delay |= (spicfg->t2cdelay << SPIDELAY_T2CDELAY_SHIFT)
+						& SPIDELAY_T2CDELAY_MASK;
+		}
 
-		if (spi->mode & SPI_READY)
+		if (spi->mode & SPI_READY) {
 			spifmt |= SPIFMT_WAITENA_MASK;
+			delay |= (spicfg->t2edelay << SPIDELAY_T2EDELAY_SHIFT)
+						& SPIDELAY_T2EDELAY_MASK;
+			delay |= (spicfg->c2edelay << SPIDELAY_C2EDELAY_SHIFT)
+						& SPIDELAY_C2EDELAY_MASK;
+		}
+
+		iowrite32(delay, davinci_spi->base + SPIDELAY);
 	}
 
 	iowrite32(spifmt, davinci_spi->base + SPIFMT0);