gpio.c: dummy SPI transfer after the real one to ensure high state on all CS lines

1ad18b77 · Tomasz Wlostowski · Alessandro Rubini · 206ec171 · 1ad18b77 · 1ad18b77
Commit 1ad18b77 authored May 15, 2012 by Tomasz Wlostowski Committed by Alessandro Rubini May 15, 2012
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Showing with 11 additions and 1 deletion

fine-delay.h fine-delay.h +1 -0

gpio.c gpio.c +10 -1

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--- a/fine-delay.h
+++ b/fine-delay.h
@@ -236,6 +236,7 @@ enum fd_acam_modes {
 #define ACAM_MASK		((1<<29) - 1) /* 28 bits */

 /* SPI Bus chip selects */
+#define FD_CS_NONE	0	/* Nothing */
 #define FD_CS_PLL	1	/* AD9516 PLL */
 #define FD_CS_GPIO	2	/* MCP23S17 GPIO */


--- a/gpio.c
+++ b/gpio.c
@@ -18,8 +18,13 @@

 static int gpio_writel(struct spec_fd *fd, int val, int reg)
 {
-	return fd_spi_xfer(fd, FD_CS_GPIO, 24,
+	int rval = fd_spi_xfer(fd, FD_CS_GPIO, 24,
 			   0x4e0000 | (reg << 8) | val, NULL);
+
+	fd_spi_xfer(fd, FD_CS_NONE, 24,
+			  0, NULL);
+	
+	return rval;
 }

 static int gpio_readl(struct spec_fd *fd, int reg)
@@ -29,6 +34,10 @@ static int gpio_readl(struct spec_fd *fd, int reg)

 	err = fd_spi_xfer(fd, FD_CS_GPIO, 24,
 			  0x4f0000 | (reg << 8), &ret);
+
+	fd_spi_xfer(fd, FD_CS_NONE, 24,
+			  0, NULL);
+
 	if (err < 0)
 		return err;
 	return ret & 0xff;