[PATCH 3/4] ARM: imx: imx31: Introduce and use UART_BASE_ADDR(n)

[Marek Vasut]

Introduce helper macro UART_BASE_ADDR(n), which returns Nth UART base
address. Convert all board configurations to this new macro. This is the
first step toward switching CONFIG_MXC_UART_BASE to Kconfig. This is a
clean up, no functional change.

The new macro contains compile-time test to verify N is in suitable
range. The test works such that it multiplies constant N by constant
double-negation of size of a non-empty structure, i.e. it multiplies
constant N by constant 1 in each successful compilation case.

The non-empty structure may contain C11 _Static_assert(), make use of
this and place the kernel variant of static assert in there, so that
it performs the compile-time check for N in the correct range. Note
that it is not possible to directly use static_assert in compound
statements, hence this convoluted construct.

Signed-off-by: Marek Vasut <marex at denx.de>
Cc: Fabio Estevam <festevam at denx.de>
Cc: Peng Fan <peng.fan at nxp.com>
Cc: Stefano Babic <sbabic at denx.de>
---
 arch/arm/include/asm/arch-mx31/imx-regs.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm/include/asm/arch-mx31/imx-regs.h b/arch/arm/include/asm/arch-mx31/imx-regs.h
index 566db549ec6..d5c0ed8e6c2 100644
--- a/arch/arm/include/asm/arch-mx31/imx-regs.h
+++ b/arch/arm/include/asm/arch-mx31/imx-regs.h
@@ -598,6 +598,18 @@ struct esdc_regs {
 #define UART4_BASE	0x43FB0000
 #define UART5_BASE	0x43FB4000
 
+#define UART_BASE_ADDR(n)	(			\
+	!!sizeof(struct {				\
+		static_assert((n) >= 1 && (n) <= 5);	\
+		int pad;				\
+		}) * (					\
+	(n) == 1 ? UART1_BASE :				\
+	(n) == 2 ? UART2_BASE :				\
+	(n) == 3 ? UART3_BASE :				\
+	(n) == 4 ? UART4_BASE :				\
+	UART5_BASE_ADDR)				\
+	)
+
 #define I2C1_BASE_ADDR          0x43f80000
 #define I2C1_CLK_OFFSET		26
 #define I2C2_BASE_ADDR          0x43F98000
-- 
2.35.1