net: ethernet: bgmac: init sequence bug

Fix a bug in the 'bgmac' driver init sequence that blind writes for init
sequence where it should preserve most bits other than the ones it is
deliberately manipulating.

The code now checks to see if the adapter needs to be brought out of
reset (where as before it was doing an IDM write to bring it out of
reset regardless of whether it was in reset or not).  Also, removed
unnecessary usleeps (as there is already a read present to flush the
IDM writes).

Signed-off-by: Zac Schroff <zschroff@broadcom.com>
Signed-off-by: Jon Mason <jon.mason@broadcom.com>
Fixes: f6a95a2495 ("net: ethernet: bgmac: Add platform device support")
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bgmac-platform.c

@@ -51,8 +51,7 @@ static void platform_bgmac_idm_write(struct bgmac *bgmac, u16 offset, u32 value)
 
 static bool platform_bgmac_clk_enabled(struct bgmac *bgmac)
 {
-	if ((bgmac_idm_read(bgmac, BCMA_IOCTL) &
-	     (BCMA_IOCTL_CLK | BCMA_IOCTL_FGC)) != BCMA_IOCTL_CLK)
+	if ((bgmac_idm_read(bgmac, BCMA_IOCTL) & BGMAC_CLK_EN) != BGMAC_CLK_EN)
 		return false;
 	if (bgmac_idm_read(bgmac, BCMA_RESET_CTL) & BCMA_RESET_CTL_RESET)
 		return false;
@@ -61,15 +60,25 @@ static bool platform_bgmac_clk_enabled(struct bgmac *bgmac)
 
 static void platform_bgmac_clk_enable(struct bgmac *bgmac, u32 flags)
 {
-	bgmac_idm_write(bgmac, BCMA_IOCTL,
-			(BCMA_IOCTL_CLK | BCMA_IOCTL_FGC | flags));
-	bgmac_idm_read(bgmac, BCMA_IOCTL);
+	u32 val;
 
-	bgmac_idm_write(bgmac, BCMA_RESET_CTL, 0);
-	bgmac_idm_read(bgmac, BCMA_RESET_CTL);
-	udelay(1);
+	/* The Reset Control register only contains a single bit to show if the
+	 * controller is currently in reset.  Do a sanity check here, just in
+	 * case the bootloader happened to leave the device in reset.
+	 */
+	val = bgmac_idm_read(bgmac, BCMA_RESET_CTL);
+	if (val) {
+		bgmac_idm_write(bgmac, BCMA_RESET_CTL, 0);
+		bgmac_idm_read(bgmac, BCMA_RESET_CTL);
+		udelay(1);
+	}
 
-	bgmac_idm_write(bgmac, BCMA_IOCTL, (BCMA_IOCTL_CLK | flags));
+	val = bgmac_idm_read(bgmac, BCMA_IOCTL);
+	/* Some bits of BCMA_IOCTL set by HW/ATF and should not change */
+	val |= flags & ~(BGMAC_AWCACHE | BGMAC_ARCACHE | BGMAC_AWUSER |
+			 BGMAC_ARUSER);
+	val |= BGMAC_CLK_EN;
+	bgmac_idm_write(bgmac, BCMA_IOCTL, val);
 	bgmac_idm_read(bgmac, BCMA_IOCTL);
 	udelay(1);
 }

drivers/net/ethernet/broadcom/bgmac.h

@@ -213,6 +213,22 @@
 /* BCMA GMAC core specific IO Control (BCMA_IOCTL) flags */
 #define BGMAC_BCMA_IOCTL_SW_CLKEN		0x00000004	/* PHY Clock Enable */
 #define BGMAC_BCMA_IOCTL_SW_RESET		0x00000008	/* PHY Reset */
+/* The IOCTL values appear to be different in NS, NSP, and NS2, and do not match
+ * the values directly above
+ */
+#define BGMAC_CLK_EN				BIT(0)
+#define BGMAC_RESERVED_0			BIT(1)
+#define BGMAC_SOURCE_SYNC_MODE_EN		BIT(2)
+#define BGMAC_DEST_SYNC_MODE_EN			BIT(3)
+#define BGMAC_TX_CLK_OUT_INVERT_EN		BIT(4)
+#define BGMAC_DIRECT_GMII_MODE			BIT(5)
+#define BGMAC_CLK_250_SEL			BIT(6)
+#define BGMAC_AWCACHE				(0xf << 7)
+#define BGMAC_RESERVED_1			(0x1f << 11)
+#define BGMAC_ARCACHE				(0xf << 16)
+#define BGMAC_AWUSER				(0x3f << 20)
+#define BGMAC_ARUSER				(0x3f << 26)
+#define BGMAC_RESERVED				BIT(31)
 
 /* BCMA GMAC core specific IO status (BCMA_IOST) flags */
 #define BGMAC_BCMA_IOST_ATTACHED		0x00000800