ARM: Davinci: UART: Fix bug with serial ports registration

This bug occurs when the davinci serial code tries to register UART(X) when
UART(X-1) or UART(X-2) is not enabled in the structure uart_config of the board
setup code:

This works: .enabled_uarts = (1 << 0)
This works: .enabled_uarts = (1 << 0) | (1 << 1)
This works: .enabled_uarts = (1 << 0) | (1 << 1) | | (1 << 2)
This fails: .enabled_uarts = (1 << 1)
This fails: .enabled_uarts = (1 << 1) | (1 << 2)
This fails: .enabled_uarts = (1 << 0) | (1 << 2)

The bug is triggered by the fact that the 8250 serial driver stops parsing the
serial_platform_data structure as soon as it sees a zero flags entry. Thus the
davinci serial registration code (serial.c) must <pack> the serial_platform_data
structure and only clear the flags entry when there is no more devices following.

Tested on DM6446 and DM355 custom boards.
Signed-off-by: Hugo Villeneuve <hugo@hugovil.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

arch/arm/mach-davinci/serial.c

@@ -49,36 +49,24 @@ static inline void serial_write_reg(struct plat_serial8250_port *p, int offset,
 	__raw_writel(value, IO_ADDRESS(p->mapbase) + offset);
 }
 
-static struct plat_serial8250_port serial_platform_data[] = {
-	{
-		.mapbase	= DAVINCI_UART0_BASE,
-		.irq		= IRQ_UARTINT0,
-		.flags		= UPF_BOOT_AUTOCONF | UPF_SKIP_TEST |
-				  UPF_IOREMAP,
-		.iotype		= UPIO_MEM,
-		.regshift	= 2,
-	},
-	{
-		.mapbase	= DAVINCI_UART1_BASE,
-		.irq		= IRQ_UARTINT1,
-		.flags		= UPF_BOOT_AUTOCONF | UPF_SKIP_TEST |
-				  UPF_IOREMAP,
-		.iotype		= UPIO_MEM,
-		.regshift	= 2,
-	},
-	{
-		.mapbase	= DAVINCI_UART2_BASE,
-		.irq		= IRQ_UARTINT2,
-		.flags		= UPF_BOOT_AUTOCONF | UPF_SKIP_TEST |
-				  UPF_IOREMAP,
-		.iotype		= UPIO_MEM,
-		.regshift	= 2,
-	},
-	{
-		.flags		= 0
-	},
+static const resource_size_t serial_mapbase[] = {
+	DAVINCI_UART0_BASE,
+	DAVINCI_UART1_BASE,
+	DAVINCI_UART2_BASE,
 };
 
+static const unsigned int serial_irq[] = {
+	IRQ_UARTINT0,
+	IRQ_UARTINT1,
+	IRQ_UARTINT2,
+};
+
+/*
+ * The additional entry is present because the list must be terminated with a
+ * zero flags entry.
+ */
+static struct plat_serial8250_port serial_platform_data[DAVINCI_MAX_NR_UARTS + 1];
+
 static struct platform_device serial_device = {
 	.name			= "serial8250",
 	.id			= PLAT8250_DEV_PLATFORM,
@@ -112,29 +100,31 @@ void __init davinci_serial_init(struct davinci_uart_config *info)
 	char name[16];
 	struct clk *uart_clk;
 	struct device *dev = &serial_device.dev;
+	struct plat_serial8250_port *p = serial_platform_data;
 
 	/*
 	 * Make sure the serial ports are muxed on at this point.
-	 * You have to mux them off in device drivers later on
-	 * if not needed.
+	 * You have to mux them off in device drivers later on if not needed.
 	 */
 	for (i = 0; i < DAVINCI_MAX_NR_UARTS; i++) {
-		struct plat_serial8250_port *p = serial_platform_data + i;
-
-		if (!(info->enabled_uarts & (1 << i))) {
-			p->flags = 0;
+		if (!(info->enabled_uarts & (1 << i)))
 			continue;
-		}
 
-		if (cpu_is_davinci_dm646x()) {
-			p->iotype = UPIO_MEM32;
-		}
+		/* fill-in common members */
+		p->flags = UPF_BOOT_AUTOCONF | UPF_SKIP_TEST | UPF_IOREMAP;
+		p->regshift = 2;
 
-		if (cpu_is_davinci_dm355()) {
-			if (i == 2) {
-				p->mapbase = (unsigned long)DM355_UART2_BASE;
-				p->irq = IRQ_DM355_UARTINT2;
-			}
+		if (cpu_is_davinci_dm646x())
+			p->iotype = UPIO_MEM32;
+		else
+			p->iotype = UPIO_MEM;
+
+		if (cpu_is_davinci_dm355() && (i == 2)) {
+			p->mapbase = DM355_UART2_BASE;
+			p->irq = IRQ_DM355_UARTINT2;
+		} else {
+			p->mapbase = serial_mapbase[i];
+			p->irq = serial_irq[i];
 		}
 
 		sprintf(name, "uart%d", i);
@@ -147,7 +137,12 @@ void __init davinci_serial_init(struct davinci_uart_config *info)
 			clk_enable(uart_clk);
 			davinci_serial_reset(p);
 		}
+
+		p++; /* Point to next entry */
 	}
+
+	/* Terminate the list with a zero flags entry */
+	p->flags = 0;
 }
 
 static int __init davinci_init(void)