regmap: mmio: Revert to v4.4 endianness handling

broonie · broonie · commit 320549a22484 · 2016-02-05T11:22:04.000Z
Commit 29bb45f (regmap-mmio: Use native endianness for read/write) attempted to fix some long standing bugs in the MMIO implementation for big endian systems caused by duplicate byte swapping in both regmap and readl()/writel() which affected MIPS systems as when they are in big endian mode they flip the endianness of all registers in the system, not just the CPU. MIPS systems had worked around this by declaring regmap using IPs as little endian which is inaccurate, unfortunately the issue had not been reported. Sadly the fix makes things worse rather than better. By changing the behaviour to match the documentation it caused behaviour changes for other IPs which broke them and by using the __raw I/O accessors to avoid the endianness swapping in readl()/writel() it removed some memory ordering guarantees and could potentially generate unvirtualisable instructions on some architectures. Unfortunately sorting out all this mess in any half way sensible fashion was far too invasive to go in during an -rc cycle so instead let's go back to the old broken behaviour for v4.5, the better fixes are already queued for v4.6. This does mean that we keep the broken MIPS DTs for another release but that seems the least bad way of handling the situation. Reported-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/arch/mips/boot/dts/brcm/bcm6328.dtsi b/arch/mips/boot/dts/brcm/bcm6328.dtsi
@@ -74,6 +74,7 @@
 		timer: timer@10000040 {
 			compatible = "syscon";
 			reg = <0x10000040 0x2c>;
+			little-endian;
 		};
 
 		reboot {
diff --git a/arch/mips/boot/dts/brcm/bcm7125.dtsi b/arch/mips/boot/dts/brcm/bcm7125.dtsi
@@ -98,6 +98,7 @@
 		sun_top_ctrl: syscon@404000 {
 			compatible = "brcm,bcm7125-sun-top-ctrl", "syscon";
 			reg = <0x404000 0x60c>;
+			little-endian;
 		};
 
 		reboot {
diff --git a/arch/mips/boot/dts/brcm/bcm7346.dtsi b/arch/mips/boot/dts/brcm/bcm7346.dtsi
@@ -118,6 +118,7 @@
 		sun_top_ctrl: syscon@404000 {
 			compatible = "brcm,bcm7346-sun-top-ctrl", "syscon";
 			reg = <0x404000 0x51c>;
+			little-endian;
 		};
 
 		reboot {
diff --git a/arch/mips/boot/dts/brcm/bcm7358.dtsi b/arch/mips/boot/dts/brcm/bcm7358.dtsi
@@ -112,6 +112,7 @@
 		sun_top_ctrl: syscon@404000 {
 			compatible = "brcm,bcm7358-sun-top-ctrl", "syscon";
 			reg = <0x404000 0x51c>;
+			little-endian;
 		};
 
 		reboot {
diff --git a/arch/mips/boot/dts/brcm/bcm7360.dtsi b/arch/mips/boot/dts/brcm/bcm7360.dtsi
@@ -112,6 +112,7 @@
 		sun_top_ctrl: syscon@404000 {
 			compatible = "brcm,bcm7360-sun-top-ctrl", "syscon";
 			reg = <0x404000 0x51c>;
+			little-endian;
 		};
 
 		reboot {
diff --git a/arch/mips/boot/dts/brcm/bcm7362.dtsi b/arch/mips/boot/dts/brcm/bcm7362.dtsi
@@ -118,6 +118,7 @@
 		sun_top_ctrl: syscon@404000 {
 			compatible = "brcm,bcm7362-sun-top-ctrl", "syscon";
 			reg = <0x404000 0x51c>;
+			little-endian;
 		};
 
 		reboot {
diff --git a/arch/mips/boot/dts/brcm/bcm7420.dtsi b/arch/mips/boot/dts/brcm/bcm7420.dtsi
@@ -99,6 +99,7 @@
 		sun_top_ctrl: syscon@404000 {
 			compatible = "brcm,bcm7420-sun-top-ctrl", "syscon";
 			reg = <0x404000 0x60c>;
+			little-endian;
 		};
 
 		reboot {
diff --git a/arch/mips/boot/dts/brcm/bcm7425.dtsi b/arch/mips/boot/dts/brcm/bcm7425.dtsi
@@ -100,6 +100,7 @@
 		sun_top_ctrl: syscon@404000 {
 			compatible = "brcm,bcm7425-sun-top-ctrl", "syscon";
 			reg = <0x404000 0x51c>;
+			little-endian;
 		};
 
 		reboot {
diff --git a/arch/mips/boot/dts/brcm/bcm7435.dtsi b/arch/mips/boot/dts/brcm/bcm7435.dtsi
@@ -114,6 +114,7 @@
 		sun_top_ctrl: syscon@404000 {
 			compatible = "brcm,bcm7425-sun-top-ctrl", "syscon";
 			reg = <0x404000 0x51c>;
+			little-endian;
 		};
 
 		reboot {
diff --git a/drivers/base/regmap/regmap-mmio.c b/drivers/base/regmap/regmap-mmio.c
@@ -133,17 +133,17 @@ static int regmap_mmio_gather_write(void *context,
 	while (val_size) {
 		switch (ctx->val_bytes) {
 		case 1:
-			__raw_writeb(*(u8 *)val, ctx->regs + offset);
+			writeb(*(u8 *)val, ctx->regs + offset);
 			break;
 		case 2:
-			__raw_writew(*(u16 *)val, ctx->regs + offset);
+			writew(*(u16 *)val, ctx->regs + offset);
 			break;
 		case 4:
-			__raw_writel(*(u32 *)val, ctx->regs + offset);
+			writel(*(u32 *)val, ctx->regs + offset);
 			break;
 #ifdef CONFIG_64BIT
 		case 8:
-			__raw_writeq(*(u64 *)val, ctx->regs + offset);
+			writeq(*(u64 *)val, ctx->regs + offset);
 			break;
 #endif
 		default:
@@ -193,17 +193,17 @@ static int regmap_mmio_read(void *context,
 	while (val_size) {
 		switch (ctx->val_bytes) {
 		case 1:
-			*(u8 *)val = __raw_readb(ctx->regs + offset);
+			*(u8 *)val = readb(ctx->regs + offset);
 			break;
 		case 2:
-			*(u16 *)val = __raw_readw(ctx->regs + offset);
+			*(u16 *)val = readw(ctx->regs + offset);
 			break;
 		case 4:
-			*(u32 *)val = __raw_readl(ctx->regs + offset);
+			*(u32 *)val = readl(ctx->regs + offset);
 			break;
 #ifdef CONFIG_64BIT
 		case 8:
-			*(u64 *)val = __raw_readq(ctx->regs + offset);
+			*(u64 *)val = readq(ctx->regs + offset);
 			break;
 #endif
 		default:
