Staging: olpc_dcon: replace some magic numbers

This patch replace some magic numbers. I believe it makes
the driver more readable.

The magic number 0x26 is the XO system embedded controller
(EC) command 'DCON power enable/disable'.

Number 0x41, and 0x42 are special memory controller settings
register.  The 0x41 initialize bit sequence 0x101 means:
enable memory power down function and special SDRAM clock
delay for synchronize SDRAM output and clock signal.

The 0x42 initialize squence 0x101 is wrong.  According to
the specification Bit 8 is reserved, thus not in use.
I removed it.
Signed-off-by: Jens Frederich <jfrederich@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/olpc_dcon/olpc_dcon.c

@@ -90,9 +90,10 @@ static int dcon_hw_init(struct dcon_priv *dcon, int is_init)
 
 	/* SDRAM setup/hold time */
 	dcon_write(dcon, 0x3a, 0xc040);
-	dcon_write(dcon, 0x41, 0x0000);
-	dcon_write(dcon, 0x41, 0x0101);
-	dcon_write(dcon, 0x42, 0x0101);
+	dcon_write(dcon, DCON_REG_MEM_OPT_A, 0x0000);  /* clear option bits */
+	dcon_write(dcon, DCON_REG_MEM_OPT_A,
+				MEM_DLL_CLOCK_DELAY | MEM_POWER_DOWN);
+	dcon_write(dcon, DCON_REG_MEM_OPT_B, MEM_SOFT_RESET);
 
 	/* Colour swizzle, AA, no passthrough, backlight */
 	if (is_init) {
@@ -126,7 +127,7 @@ static int dcon_bus_stabilize(struct dcon_priv *dcon, int is_powered_down)
 power_up:
 	if (is_powered_down) {
 		x = 1;
-		x = olpc_ec_cmd(0x26, (unsigned char *)&x, 1, NULL, 0);
+		x = olpc_ec_cmd(EC_DCON_POWER_MODE, (u8 *)&x, 1, NULL, 0);
 		if (x) {
 			pr_warn("unable to force dcon to power up: %d!\n", x);
 			return x;
@@ -144,7 +145,7 @@ static int dcon_bus_stabilize(struct dcon_priv *dcon, int is_powered_down)
 		pr_err("unable to stabilize dcon's smbus, reasserting power and praying.\n");
 		BUG_ON(olpc_board_at_least(olpc_board(0xc2)));
 		x = 0;
-		olpc_ec_cmd(0x26, (unsigned char *)&x, 1, NULL, 0);
+		olpc_ec_cmd(EC_DCON_POWER_MODE, (u8 *)&x, 1, NULL, 0);
 		msleep(100);
 		is_powered_down = 1;
 		goto power_up;	/* argh, stupid hardware.. */
@@ -208,7 +209,7 @@ static void dcon_sleep(struct dcon_priv *dcon, bool sleep)
 
 	if (sleep) {
 		x = 0;
-		x = olpc_ec_cmd(0x26, (unsigned char *)&x, 1, NULL, 0);
+		x = olpc_ec_cmd(EC_DCON_POWER_MODE, (u8 *)&x, 1, NULL, 0);
 		if (x)
 			pr_warn("unable to force dcon to power down: %d!\n", x);
 		else

drivers/staging/olpc_dcon/olpc_dcon.h

@@ -22,15 +22,24 @@
 #define MODE_DEBUG	(1<<14)
 #define MODE_SELFTEST	(1<<15)
 
-#define DCON_REG_HRES		2
-#define DCON_REG_HTOTAL		3
-#define DCON_REG_HSYNC_WIDTH	4
-#define DCON_REG_VRES		5
-#define DCON_REG_VTOTAL		6
-#define DCON_REG_VSYNC_WIDTH	7
-#define DCON_REG_TIMEOUT	8
-#define DCON_REG_SCAN_INT	9
-#define DCON_REG_BRIGHT		10
+#define DCON_REG_HRES		0x2
+#define DCON_REG_HTOTAL		0x3
+#define DCON_REG_HSYNC_WIDTH	0x4
+#define DCON_REG_VRES		0x5
+#define DCON_REG_VTOTAL		0x6
+#define DCON_REG_VSYNC_WIDTH	0x7
+#define DCON_REG_TIMEOUT	0x8
+#define DCON_REG_SCAN_INT	0x9
+#define DCON_REG_BRIGHT		0x10
+#define DCON_REG_MEM_OPT_A	0x41
+#define DCON_REG_MEM_OPT_B	0x42
+
+/* Load Delay Locked Loop (DLL) settings for clock delay */
+#define MEM_DLL_CLOCK_DELAY	(1<<0)
+/* Memory controller power down function */
+#define MEM_POWER_DOWN  	(1<<8)
+/* Memory controller software reset */
+#define MEM_SOFT_RESET		(1<<0)
 
 /* Status values */
 

include/linux/olpc-ec.h

@@ -6,6 +6,7 @@
 #define EC_WRITE_SCI_MASK		0x1b
 #define EC_WAKE_UP_WLAN			0x24
 #define EC_WLAN_LEAVE_RESET		0x25
+#define EC_DCON_POWER_MODE		0x26
 #define EC_READ_EB_MODE			0x2a
 #define EC_SET_SCI_INHIBIT		0x32
 #define EC_SET_SCI_INHIBIT_RELEASE	0x34